Electron-phonon coupling in one dimension
International Nuclear Information System (INIS)
Apostol, M.; Baldea, I.
1981-08-01
The Ward identity is derived for the electron-phonon coupling in one dimension and the spectrum of elementary excitations is calculated by assuming that the Fermi distribution is not strongly distorted by interaction. The electron-phonon vertex is renormalized in the case of the forward scattering and Migdal's theorem is discussed. A model is proposed for the giant Kohn anomaly. The dip in the phonon spectrum is obtained and found to be in agreement with the experimental data for KCP. (author)
The Electron-Phonon Interaction in Strongly Correlated Systems
International Nuclear Information System (INIS)
Castellani, C.; Grilli, M.
1995-01-01
We analyze the effect of strong electron-electron repulsion on the electron-phonon interaction from a Fermi-liquid point of view and show that the electron-electron interaction is responsible for vertex corrections, which generically lead to a strong suppression of the electron-phonon coupling in the v F q/ω >>1 region, while such effect is not present when v F q/ω F is the Fermi velocity and q and ω are the transferred momentum and frequency respectively. In particular the e-ph scattering is suppressed in transport properties which are dominated by low-energy-high-momentum processes. On the other hand, analyzing the stability criterion for the compressibility, which involves the effective interactions in the dynamical limit, we show that a sizable electron-phonon interaction can push the system towards a phase-separation instability. Finally a detailed analysis of these ideas is carried out using a slave-boson approach for the infinite-U three-band Hubbard model in the presence of a coupling between the local hole density and a dispersionless optical phonon. (author)
Electron-phonon coupling in the rare-earth metals
DEFF Research Database (Denmark)
Skriver, Hans Lomholt; Mertig, I.
1990-01-01
We have estimated the strength of the mass enhancement of the conduction electrons due to electron-phonon interaction in the rare metals Sc, Y, and La–Lu. The underlying self-consistent energy bands were obtained by means of the scalar relativistic linear-muffin-tin-orbital method, and the electron......-phonon parameters were calculated within the Gaspari-Gyorffy formulation. For the heavier rare earths Gd–Tm spin polarization was included both in the band-structure calculations and in the treatment of the electron-phonon coupling to take into account the spin splitting of the conduction electrons induced by the 4...
Electron-phonon coupling of the actinide metals
DEFF Research Database (Denmark)
Skriver, H. L.; Mertig, I.
1985-01-01
The authors have estimated the strength of the electron-phonon coupling in Fr and Ra plus the light actinides Ac through Pu. The underlying self-consistent band-structure calculations were performed by the scalar relativistic linear-muffin-tin-orbital method including l quantum numbers s through g......, and the electron-phonon parameters were obtained within the rigid-atomic-sphere approximation. The electron-phonon coupling in Fr through Th is found to be dominated by pd and df scattering and in Pa through Pu by pd and fg scattering. At the equilibrium volumes and as a function of atomic number, the electron...... be related to the changeover from an s-to- d to an s-to-f electronic transition and a related change in the topology of the Fermi surface...
Enhanced Electron-Phonon Coupling at Metal Surfaces
Energy Technology Data Exchange (ETDEWEB)
Plummer, Ward E.
2010-08-04
The Born-Oppenheimer approximation (BOA) decouples electronic from nuclear motion, providing a focal point for most quantum mechanics textbooks. However, a multitude of important chemical, physical and biological phenomena are driven by violations of this approximation. Vibronic interactions are a necessary ingredient in any process that makes or breaks a covalent bond, for example, conventional catalysis or enzymatically delivered biological reactions. Metastable phenomena associated with defects and dopants in semiconductors, oxides, and glasses entail violation of the BOA. Charge exchange in inorganic polymers, organic slats and biological systems involves charge- induced distortions of the local structure. A classic example is conventional superconductivity, which is driven by the electron-lattice interaction. High-resolution angle-resolved photoemission experiments are yielding new insight into the microscopic origin of electron-phonon coupling (EPC) in anisotropic two-dimensional systems. Our recent surface phonon measurement on the surface of a high-Tc material clearly indicates an important momentum dependent EPC in these materials. In the last few years we have shifted our research focus from solely looking at electron phonon coupling to examining the structure/functionality relationship at the surface of complex transition metal compounds. The investigation on electron phonon coupling has allowed us to move to systems where there is coupling between the lattice, the electrons and the spin.
Electron-phonon coupling of the actinide metals
DEFF Research Database (Denmark)
Skriver, H. L.; Mertig, I.
1985-01-01
The authors have estimated the strength of the electron-phonon coupling in Fr and Ra plus the light actinides Ac through Pu. The underlying self-consistent band-structure calculations were performed by the scalar relativistic linear-muffin-tin-orbital method including l quantum numbers s through g......-phonon parameter λ is found to attain its maximum value in Ac, and they predict a transition temperature of 9K for this metal. In the light actinides Th through Pu, λ is found to be of order 0.4 and within a factor of 2 of experiments which is also the accuracy found in studies of the transition metals...
Electron-phonon coupling in quasi free-standing graphene
DEFF Research Database (Denmark)
Christian Johannsen, Jens; Ulstrup, Søren; Bianchi, Marco
2013-01-01
Quasi free-standing monolayer graphene can be produced by intercalating species like oxygen or hydrogen between epitaxial graphene and the substrate crystal. If the graphene is indeed decoupled from the substrate, one would expect the observation of a similar electronic dispersion and many......-body effects, irrespective of the substrate and the material used to achieve the decoupling. Here we investigate the electron-phonon coupling in two different types of quasi free-standing monolayer graphene: decoupled from SiC via hydrogen intercalation and decoupled from Ir via oxygen intercalation. Both...
Electron-phonon coupling in graphene placed between magnetic Li and Si layers on cobalt
Usachov, Dmitry Yu.; Fedorov, Alexander V.; Vilkov, Oleg Yu.; Ogorodnikov, Ilya I.; Kuznetsov, Mikhail V.; Grüneis, Alexander; Laubschat, Clemens; Vyalikh, Denis V.
2018-02-01
Using angle-resolved photoemission spectroscopy (ARPES), we study the electronic structure and electron-phonon coupling in a Li-doped graphene monolayer decoupled from the Co(0001) substrate by intercalation of silicon. Based on the photoelectron diffraction measurements, we disclose the structural properties of the Si/Co interface. Our density functional theory calculations demonstrate that in the studied Li/graphene/Si/Co system the magnetism of Co substrate induces notable magnetic moments on Li and Si atoms. At the same time graphene remains almost nonmagnetic and clamped between two magnetically active atomic layers with antiparallel magnetizations. ARPES maps of the graphene Fermi surface reveal strong electron doping, which may lead to superconductivity mediated by electron-phonon coupling (EPC). Analysis of the spectral function of photoelectrons reveals apparent anisotropy of EPC in the k space. These properties make the studied system tempting for studying the relation between superconductivity and magnetism in two-dimensional materials.
Energy Technology Data Exchange (ETDEWEB)
Zhou, X.J.
2010-04-30
thought possible only a decade ago. This revolution of the ARPES technique and its scientific impact result from dramatic advances in four essential components: instrumental resolution and efficiency, sample manipulation, high quality samples and well-matched scientific issues. The purpose of this treatise is to go through the prominent results obtained from ARPES on cuprate superconductors. Because there have been a number of recent reviews on the electronic structures of high-T{sub c} materials, we will mainly present the latest results not covered previously, with a special attention given on the electron-phonon interaction in cuprate superconductors. What has emerged is rich information about the anomalous electron-phonon interaction well beyond the traditional views of the subject. It exhibits strong doping, momentum and phonon symmetry dependence, and shows complex interplay with the strong electron-electron interaction in these materials. ARPES experiments have been instrumental in identifying the electronic structure, observing and detailing the electron-phonon mode coupling behavior, and mapping the doping evolution of the high-T{sub c} cuprates. The spectra evolve from the strongly coupled, polaronic spectra seen in underdoped cuprates to the Migdal-Eliashberg like spectra seen in the optimally and overdoped cuprates. In addition to the marked doping dependence, the cuprates exhibit pronounced anisotropy with direction in the Brillouin zone: sharp quasiparticles along the nodal direction that broaden significantly in the anti-nodal region of the underdoped cuprates, an anisotropic electron-phonon coupling vertex for particular modes identified in the optimal and overdoped compounds, and preferential scattering across the two parallel pieces of Fermi surface in the antinodal region for all doping levels. This also contributes to the pseudogap effect. To the extent that the Migdal-Eliashberg picture applies, the spectra of the cuprates bear resemblance to that
Electron-phonon coupling in BaFe2As2: A possible origin of nematic phase
Zhang, Anmin; Ji, Jianting; Xia, Tianlong; Zhao, Guihua; Tian, Yong; Jin, Feng; Zhang, Qingming
2015-12-01
Iron-based superconductors have the second-highest superconducting transition temperature next to cuprate superconductors. There are many electronic phases such as superconducting, antiferromagnetic and nematic phases, coexisting in the family of iron pnictides. The charge/spin orders are the key factors for understanding the mechanism of high-temperature superconductivity. In this paper we have performed a Raman scattering study of parent compound BaFe2As2. A relatively strong electron-phonon coupling is observed for B1g phonon mode and is weakened after the structural transition at ∼140 K. Through a careful symmetry analysis, we revealed the possibility that B1g mode can be effectively coupled with dxz and dyz orbits. The coupling can remove the degeneracy of the two orbits and further cause the fluctuations of electronic nematic phases. The study suggests that electron-phonon coupling can be a possible origin of nematic phase.
Spin-dependent electron-phonon coupling in the valence band of single-layer WS2
DEFF Research Database (Denmark)
Hinsche, Nicki Frank; Ngankeu, Arlette S.; Guilloy, Kevin
2017-01-01
The absence of inversion symmetry leads to a strong spin-orbit splitting of the upper valence band of semiconducting single-layer transition-metal dichalchogenides such as MoS2 or WS2. This permits a direct comparison of the electron-phonon coupling strength in states that only differ by their spin....... Here, the electron-phonon coupling in the valence band maximum of single-layer WS2 is studied by first-principles calculations and angle-resolved photoemission. The coupling strength is found to be drastically different for the two spin-split branches, with calculated values of λK=0.0021 and 0.......40 for the upper and lower spin-split valence band of the freestanding layer, respectively. This difference is somewhat reduced when including scattering processes involving the Au(111) substrate present in the experiment but it remains significant, in good agreement with the experimental results....
International Nuclear Information System (INIS)
Lin, Yow-Jon; Chin, Yi-Min
2014-01-01
A correlation between the electron-phonon coupling and rectifying performance is identified for poly(3-hexylthiophene) (P3HT)/n-type Si devices and an analysis using the temperature-dependent Hall-effect characteristics is presented. The carrier mobility in the P3HT film exhibits strong temperature dependence, indicating the dominance of tunneling. However, the incorporation of titanium oxide (TiO 2 ) nanoparticles into P3HT leads to the dominance of hopping. The results demonstrate that the incorporation of TiO 2 nanoparticles into P3HT influences the electrical property of P3HT/n-type Si devices by the electron-phonon coupling modification and the increased spacing between molecules that serve to enhance the carrier mobility in P3HT
Ranges and limits of the electron-phonon coupling constant of ...
African Journals Online (AJOL)
A simplified study of the effect of including self energy and vertex corrections to the BCS critical temperature Tc expression is carried out her to identify the possible ranges and limits of the electron-phonon coupling constant λ in superconductivity. The results show that the inclusion of the self energy will reduce the BCS Tc to ...
Electron-phonon coupling of light-actinides. Effect of spin-orbit coupling
Energy Technology Data Exchange (ETDEWEB)
Gonzalez-Castelazo, Paola; Pena-Seaman, Omar de la [Benemerita Universidad Autonoma de Puebla (BUAP), Institute of Physics (IFUAP) (Mexico); Heid, Rolf; Bohnen, Klaus-Peter [Karlsruher Institut fuer Technologie (KIT), Institut fuer Festkoerperphysik (IFP) (Germany)
2014-07-01
The physics of actinide metals is quite complex and rich due to the behavior of 5f electrons in the valence region: it goes from itinerant on the early stages of the actinide series to highly localized for the elements with a higher number of 5f electrons involved. In addition, in this systems should be mandatory the inclusion of spin-orbit coupling (SOC). However, only in few cases on electronic and lattice dynamical properties the SOC has been taking into account, while for the electron-phonon (e-ph) coupling such analysis has not been performed so far. Thus, as a first approach we have systematically studied the SOC influence on the full-phonon dispersion and the e-ph coupling for the simplest light-actinide metals: Ac and Th. These elements have been studied within the framework of density functional perturbation theory, using a mixed-basis pseudopotential method. The full-phonon dispersion as well as the Eliashberg spectral function and the electron-phonon coupling parameter have been calculated with and without SOC. The observed effects of SOC in the full-phonon dispersion and Eliashberg function are discussed in detail, together with an analysis of the differences on the electronic properties due to the SOC inclusion in the calculations.
Microwave Detection of Electron-Phonon Interactions in a Cavity-Coupled Double Quantum Dot
Hartke, T. R.; Liu, Y.-Y.; Gullans, M. J.; Petta, J. R.
2018-03-01
Quantum confinement leads to the formation of discrete electronic states in quantum dots. Here we probe electron-phonon interactions in a suspended InAs nanowire double quantum dot (DQD) that is electric-dipole coupled to a microwave cavity. We apply a finite bias across the wire to drive a steady state population in the DQD excited state, enabling a direct measurement of the electron-phonon coupling strength at the DQD transition energy. The amplitude and phase response of the cavity field exhibit oscillations that are periodic in the DQD energy level detuning due to the phonon modes of the nanowire. The observed cavity phase shift is consistent with theory that predicts a renormalization of the cavity center frequency by coupling to phonons.
Nonlocal electron-phonon coupling in the pentacene crystal: Beyond the Γ-point approximation
Yi, Yuanping
2012-01-01
There is currently increasing interest in understanding the impact of the nonlocal (Peierls-type) electron-phonon mechanism on charge transport in organic molecular semiconductors. Most estimates of the non-local coupling constants reported in the literature are based on the Γ-point phonon modes. Here, the influence of phonon modes spanning the entire Brillouin zone (phonon dispersion) on the nonlocal electron-phonon couplings is investigated for the pentacene crystal. The phonon modes are obtained by using a supercell approach. The results underline that the overall nonlocal couplings are substantially underestimated by calculations taking sole account of the phonons at the Γ point of the unit cell. The variance of the transfer integrals based on Γ-point normal-mode calculations at room temperature is underestimated in some cases by 40% for herringbone-type dimers and by over 80% for cofacial dimers. Our calculations show that the overall coupling is somewhat larger for holes than for electrons. The results also suggest that the interactions of charge carriers (both electrons and holes) with acoustic and optical phonons are comparable. Therefore, an adequate description of the charge-transport properties in pentacene and similar systems requires that these two electron-phonon coupling mechanisms be treated on the same footing. © 2012 American Institute of Physics.
Anharmonic vibrational properties in periodic systems: energy, electron-phonon coupling, and stress
Monserrat, Bartomeu; Drummond, N. D.; Needs, R. J.
2013-01-01
A unified approach is used to study vibrational properties of periodic systems with first-principles methods and including anharmonic effects. Our approach provides a theoretical basis for the determination of phonon-dependent quantities at finite temperatures. The low-energy portion of the Born-Oppenheimer energy surface is mapped and used to calculate the total vibrational energy including anharmonic effects, electron-phonon coupling, and the vibrational contribution to the stress tensor. W...
Coherent dynamics of singlet fission controlled by nonlocal electron-phonon coupling
Yao, Yao
2015-01-01
Based on the Frenkel-charge transfer (CT) mixing model of singlet fission (SF), we incorporate both the local and nonlocal phonon baths in the Hamiltonian and adopt the algorithm of time-dependent density matrix renormalization group to simulate the fission process in tetracene. The endergonic SF is found to be facilitated by the robust quantum coherence, which concurrently gives rise to a notable quantum beating effect. Controlled by the nonlocal electron-phonon coupling, the density of trip...
Electron-phonon coupling effect on wakefields in piezoelectric semiconductors
Salimullah, M; Ghosh, S K; Nitta, H; Hayashi, Y
2003-01-01
Using an appropriate dielectric constant for an n-type piezoelectric semiconductor plasma and a moving test particle approach, it is shown that, besides the usual screened potential, there exists a non-Coulombian oscillatory potential or a wakefield behind a moving charged particle due to a strong resonant interaction between the charged particle and the electro-acoustic mode of the host semiconductor. With the concept of the wakefield, a possible lattice formation of colloids resulting from ion implantation in a current-carrying piezoelectric semiconductor has been examined.
Coherent dynamics of singlet fission controlled by nonlocal electron-phonon coupling
Yao, Yao
2016-03-01
Based on the Frenkel and charge transfer mixing model of singlet fission (SF), we incorporate both the local and nonlocal phonon baths into the Hamiltonian and adopt the algorithm of the time-dependent density matrix renormalization group to simulate the SF process in tetracene and pentacene. The endergonic SF is found to be facilitated by the robust quantum coherence, which concurrently gives rise to a notable quantum beating effect. Being controlled by the nonlocal electron-phonon coupling, the SF process is accelerated and the triplet yield manifests a nonlinear relationship with the singlet density.
Through a Lattice Darkly: Shedding Light on Electron-Phonon Coupling in the High Tc Cuprates
Directory of Open Access Journals (Sweden)
D. R. Garcia
2010-01-01
Full Text Available With its central role in conventional BCS superconductivity, electron-phonon coupling appears to play a more subtle role in the phase diagram of the high-temperature superconducting cuprates. Their added complexity due to potentially numerous competing phases, including charge, spin, orbital, and lattice ordering, makes teasing out any unique phenomena challenging. In this review, we present our work using angle-resolved photoemission spectroscopy (ARPES exploring the role of the lattice on the valence band electronic structure of the cuprates. We introduce the ARPES technique and its unique ability to the probe the effect of bosonic renormalization (or “kink” on near-EF band structure. Our survey begins with the establishment of the ubiquitous nodal cuprate kink leading to how isotope substitution has shed a critical new perspective on the role and strength of electron-phonon coupling. We continue with recently published work connecting the phonon dispersion seen with inelastic X-ray scattering (IXS to the location of the kink observed by ARPES near the nodal point. Finally, we present very recent and ongoing ARPES work examining how induced strain through chemical pressure provides a potentially promising avenue for understanding the broader role of the lattice to the superconducting phase and larger cuprate phase diagram.
Electronic structure and electron-phonon coupling in layered copper oxide superconductors
International Nuclear Information System (INIS)
Pickett, W.E.; Cohen, R.E.; Krakauer, H.
1991-01-01
Experimental data on the layered Cu-O superconductors seem more and more to reflect normal Fermi-liquid behavior and substantial correspondence with band structure predictions. Recent self-consistent, microscopic band theoretic calculations of the electronic structure, lattice instabilities, phonon frequencies, and electron-phonon coupling characteristics and strength for La 2 CuO 4 and YBa 2 Cu 3 O 7 are reviewed. A dominant feature of the coupling is a novel Madelung-like contribution which would be screened out in high density of states superconductors but survives in cuprates because of weak screening. Local density functional theory correctly predicts the instability of (La, Ba) 2 CuO 4 to both the low-temperature orthorhombic phase (below room temperature) and the lower-temperature tetragonal phase (below 50 K). (orig.)
First-principles method for electron-phonon coupling and electron mobility
DEFF Research Database (Denmark)
Gunst, Tue; Markussen, Troels; Stokbro, Kurt
2016-01-01
of the problem and, importantly, it keeps the anisotropy information stored in the coupling as well as the band structure. In addition, we perform calculations of the low-field mobility and its dependence on carrier density and temperature to obtain a better understanding of transport in graphene, silicene......, clamping, or similar). If the out-of-plane interaction is not actively reduced, the mobility of silicene will essentially be zero. For MoS2, we obtain several orders of magnitude lower mobilities compared to graphene in agreement with other recent theoretical results. The simulations illustrate......We present density functional theory calculations of the phonon-limited mobility in n-type monolayer graphene, silicene, and MoS2. The material properties, including the electron-phonon interaction, are calculated from first principles. We provide a detailed description of the normalized full...
Wave-vector-dependent electron-phonon coupling and the charge-density-wave transition in TbT e3
Maschek, M.; Rosenkranz, S.; Heid, R.; Said, A. H.; Giraldo-Gallo, P.; Fisher, I. R.; Weber, F.
2015-06-01
We present a high-energy-resolution inelastic x-ray scattering investigation of the soft phonon mode in the charge-density-wave (CDW) system TbT e3 . We analyze our data based on lattice dynamical calculations using density-functional-perturbation theory and find clear evidence that strongly momentum-dependent electron-phonon coupling defines the periodicity of the CDW superstructure: Our experiment reveals strong phonon softening and increased phonon linewidths over a large part in reciprocal space adjacent to the CDW ordering vector qCDW=(0 ,0 ,0.3 ) . Further, qCDW is clearly offset from the wave vector of (weak) Fermi surface nesting qFS=(0 ,0 ,0.25 ) , and our detailed analysis indicates that electron-phonon coupling is responsible for this shift. Hence, we can add TbT e3 , which was previously considered as a canonical CDW compound following the Peierls scenario, to the list of distinct charge-density-wave materials characterized by momentum-dependent electron-phonon coupling.
Kato, Takashi
2011-07-14
The electron-phonon interactions in the fractionally positively charged incommensurate tetrathiafulvalene (TTF) molecular systems are investigated. In particular, since there are fractionally positive charges per TTF molecule, it is very difficult to estimate the vibronic and electron-phonon coupling constants, and thus there have been no reports of the exact calculations in the electron-phonon coupling constants in such fractionally positively charged incommensurate systems. Therefore, in this paper, we suggest new method of accurate estimation of the electron-phonon coupling constants in the fractionally positively charged systems. Total electron-phonon coupling constants for the monocation (l(+100)) of TTF is compared with that for the monoanion (l(-100)) of tetracyanoquinodimethanide (TCNQ). Furthermore, logarithmically averaged phonon frequency for the monocation (ν(ln , +1.00)) of TTF is compared with that for the monoanion (ν(ln , -1.00)) of TCNQ. The C-C and C-S stretching mode of 1599 cm(-1) and the C-S-C and C-C-S bending mode of 472 cm(-1) strongly couple to the b(3)u highest occupied molecular orbital (HOMO) in TTF molecule. The l(+100) value for TTF molecule is estimated to be 0.274 eV, and the ν(ln , +1.00) value for TTF molecule is estimated to be 926 cm(-1). The density of states at the Fermi level (N(NM, crystal)(ε(F))(+0.59, +0.59)) values for TTF(0.59+), which are essential physical values in order to investigate the mechanisms of the non-Ohmic current-voltage characteristics excellently suggested by Cohen and Heeger et al., are also estimated. By comparing the N(NM, crystal)(ε(F))(+0.59, +0.59) values estimated by us with those estimated from the experimental results of the Pauli susceptibility and the current-voltage characteristics in TTF(0.59+) suggested by Cohen and Heeger et al., and from the band calculations, we show that the l(+0.59), ν(ln , +1.00), RE(+0.59), and N(NM, crystal)(ε(F))(+0.59, +0.59) values estimated by our
International Nuclear Information System (INIS)
2017-01-01
ForewordThis issue of J. Phys. Conf. Series contains the proceedings of the 23"r"d International Symposium on the Jahn-Teller Effect with the main title “Vibronic coupling and electron-phonon interaction in molecules and crystals”, which took place in Tartu (Estonia), August 27-September 1, 2016, bringing together over 70 participants from various fields of physics and chemistry. More information on the symposium program can be found at https://ttl.ut.ee/jt16/.The series of mostly biannual Jahn-Teller symposia started in 1976. It addresses topics involving the coupling between electronic and nuclear motions in molecules and solids in conditions of electronic degeneracy and pseudodegeneracy. The Jahn-Teller effect, pseudo Jahn-Teller effect, and related vibronic coupling and electron-phonon interactions are responsible for structural instabilities and non-trivial dynamics in polyatomic systems, including pseudo-rotations and non-adiabatic effects around conical intersections and seams, and play a key role in the explanation of seemingly diverse phenomena, such as spontaneous symmetry breakings, structural phase transitions, colossal magnetoresistance, exotic molecular magnetism, superconductivity in fullerides, giant permittivity and flexoelectricity, and chemical reactions after thermo- or photoexcitation. The meeting brings together theoreticians and experimentalists working in molecular physics and chemistry with researches working in solid state physics.A characteristic of these symposia is that they are devoted to discussion of a wide range of physical and chemical phenomena which, at first sight, are different in scope and nature, but in fact they are strongly entangled by vibronic coupling, and their joint presentation and discussion is deemed to mutually enrich the presenters from different fields with stimulating novel ideas.The 23"r"d Symposium included the following topics:• Fundamental theory, computation, and experimental observation of vibronic
Orbital dependent Rashba splitting and electron-phonon coupling of 2D Bi phase on Cu(100) surface
Energy Technology Data Exchange (ETDEWEB)
Gargiani, Pierluigi; Lisi, Simone; Betti, Maria Grazia [Dipartimento di Fisica, Università di Roma “La Sapienza,” Piazzale A. Moro 5, I-00185 Roma (Italy); Ibrahimi, Amina Taleb; Bertran, François; Le Fèvre, Patrick [Synchrotron SOLEIL, Saint-Aubin-BP 48, F-91192 Gif sur Yvette (France); Chiodo, Letizia [Center for Life Nano Science - Sapienza, Istituto Italiano di Tecnologia and European Theoretical Spectroscopy Facility (ETSF), Viale Regina Elena 291, I-00161, Roma (Italy)
2013-11-14
A monolayer of bismuth deposited on the Cu(100) surface forms a highly ordered c(2×2) reconstructed phase. The low energy single particle excitations of the c(2×2) Bi/Cu(100) present Bi-induced states with a parabolic dispersion in the energy region close to the Fermi level, as observed by angle-resolved photoemission spectroscopy. The electronic state dispersion, the charge density localization, and the spin-orbit coupling have been investigated combining photoemission spectroscopy and density functional theory, unraveling a two-dimensional Bi phase with charge density well localized at the interface. The Bi-induced states present a Rashba splitting, when the charge density is strongly localized in the Bi plane. Furthermore, the temperature dependence of the spectral density close to the Fermi level has been evaluated. Dispersive electronic states offer a large number of decay channels for transitions coupled to phonons and the strength of the electron-phonon coupling for the Bi/Cu(100) system is shown to be stronger than for Bi surfaces and to depend on the electronic state symmetry and localization.
International Nuclear Information System (INIS)
Chatterjee, P.; Chatterjee, S.
1978-01-01
The theoretical formula of McMillan has been very successful in explaining the superconducting transition temperature. In this theory the electron-phonon coupling constant was very difficult to calculate from a purely theoretical stand point until Gyorffy and Gaspari gave a theoretical formulation from the multiple scattering point of view. This theory has been very successful in explaining Tsub(c) of many superconducting elements and compounds. For the disordered solid, such as substitution alloys, this theory fails because of the breakdown of the translational symmetry used in the multiple scattering theory of Gyorffy and Gaspari. This problem can however be solved if we average the Green's function in random phase approximation (ATA). In this work we have reformulated Gyorffy and Gaspari's expression of the electron phonon coupling constant in the random phase approximation. This theory has been utilised to alloys of Nb and Mo with different concentrations. The agreement between theory and experiment appears to be very good. (author)
Strong electron-phonon interaction in the high-Tc superconductors: Evidence from the infrared
International Nuclear Information System (INIS)
Timusk, T.; Porter, C.D.; Tanner, D.B.
1991-01-01
We show that low-frequency structure in the infrared reflectance of the high-temperature superconductor YBa 2 Cu 3 O 7 results from the electron-phonon interaction. Characteristic antiresonant line shapes are seen in the phonon region of the spectrum and the frequency-dependent scattering rate of the mid-infrared electronic continuum has peaks at 150 cm -1 (19 meV) and at 360 cm -1 (45 meV) in good agreement with phonon density-of-states peaks in neutron time-of-flight spectra that develop in superconducting samples. The interaction between the phonons and the charge carriers can be understood in terms of a charged-phonon model
Rosandi, Yudi; Grossi, Joás; Bringa, Eduardo M.; Urbassek, Herbert M.
2018-01-01
The incidence of energetic laser pulses on a metal foam may lead to foam ablation. The processes occurring in the foam may differ strongly from those in a bulk metal: The absorption of laser light, energy transfer to the atomic system, heat conduction, and finally, the atomistic processes—such as melting or evaporation—may be different. In addition, novel phenomena take place, such as a reorganization of the ligament network in the foam. We study all these processes in an Au foam of average porosity 79% and an average ligament diameter of 2.5 nm, using molecular dynamics simulation. The coupling of the electronic system to the atomic system is modeled by using the electron-phonon coupling, g, and the electronic heat diffusivity, κe, as model parameters, since their actual values for foams are unknown. We show that the foam coarsens under laser irradiation. While κe governs the homogeneity of the processes, g mainly determines their time scale. The final porosity reached is independent of the value of g.
Phonovoltaic. III. Electron-phonon coupling and figure of merit of graphene:BN
Melnick, Corey; Kaviany, Massoud
2016-12-01
The phonovoltaic cell harvests optical phonons like a photovoltaic harvests photons, that is, a nonequilibrium (hot) population of optical phonons (at temperature Tp ,O) more energetic than the band gap produces electron-hole pairs in a p -n junction, which separates these pairs to produce power. A phonovoltaic material requires an optical phonon mode more energetic than its band gap and much more energetic than the thermal energy (Ep ,O>Δ Ee ,g≫kBT ), which relaxes by generating electrons and power (at rate γ˙e -p) rather than acoustic phonons and heat (at rate γ˙p -p). Graphene (h-C) is the most promising material candidate: when its band gap is tuned to its optical phonon energy without greatly reducing the electron-phonon (e -p ) coupling, it reaches a substantial figure of merit [ZpV=Δ Ee ,gγ˙e -p/Ep ,O(γ˙e -p+γ˙p -p) ≈0.8 ] . A simple tight-binding (TB) model presented here predicts that lifting the sublattice symmetry of graphene in order to open a band gap proscribes the e -p interaction at the band edge, such that γ˙e -p→0 as Δ Ee ,g→Ep ,O . However, ab initio (DFT-LDA) simulations of layered h-C/BN and substitutional h-C:BN show that the e -p coupling remains substantial in these asymmetric crystals. Indeed, h-C:BN achieves a high figure of merit (ZpV≈0.6 ). At 300 K and for a Carnot limit of 0.5 (Tp ,O=600 K) , a h-C:BN phonovoltaic can reach an efficiency of ηpV≈0.2 , double the thermoelectric efficiency (Z T ≈1 ) under similar conditions.
Quasiparticle properties of a coupled quantum-wire electron-phonon system
DEFF Research Database (Denmark)
Hwang, E. H.; Hu, Ben Yu-Kuang; Sarma, S. Das
1996-01-01
We study leading-order many-body effects of longitudinal-optical phonons on electronic properties of one-dimensional quantum-wire systems. We calculate the quasiparticle properties of a weakly polar one-dimensional electron gas in the presence of both electron-phonon and electron-electron interac...
International Nuclear Information System (INIS)
Giri, Ashutosh; Gaskins, John T.; Foley, Brian M.; Cheaito, Ramez; Hopkins, Patrick E.
2015-01-01
The electronic transport properties of metals with weak electron-phonon coupling can be influenced by non-thermal electrons. Relaxation processes involving non-thermal electrons competing with the thermalized electron system have led to inconsistencies in the understanding of how electrons scatter and relax with the less energetic lattice. Recent theoretical and computational works have shown that the rate of energy relaxation with the metallic lattice will change depending on the thermalization state of the electrons. Even though 20 years of experimental works have focused on understanding and isolating these electronic relaxation mechanisms with short pulsed irradiation, discrepancies between these existing works have not clearly answered the fundamental question of the competing effects between non-thermal and thermal electrons losing energy to the lattice. In this work, we demonstrate the ability to measure the electron relaxation for varying degrees of both electron-electron and electron-phonon thermalization. This series of measurements of electronic relaxation over a predicted effective electron temperature range up to ∼3500 K and minimum lattice temperatures of 77 K validate recent computational and theoretical works that theorize how a nonequilibrium distribution of electrons transfers energy to the lattice. Utilizing this wide temperature range during pump-probe measurements of electron-phonon relaxation, we explain discrepancies in the past two decades of literature of electronic relaxation rates. We experimentally demonstrate that the electron-phonon coupling factor in gold increases with increasing lattice temperature and laser fluences. Specifically, we show that at low laser fluences corresponding to small electron perturbations, energy relaxation between electrons and phonons is mainly governed by non-thermal electrons, while at higher laser fluences, non-thermal electron scattering with the lattice is less influential on the energy relaxation
Coupled electron-phonon transport from molecular dynamics with quantum baths
DEFF Research Database (Denmark)
Lu, Jing Tao; Wang, J. S.
2009-01-01
Based on generalized quantum Langevin equations for the tight-binding wavefunction amplitudes and lattice displacements, electron and phonon quantum transport are obtained exactly using molecular dynamics (MD) in the ballistic regime. The electron-phonon interactions can be handled with a quasi......-classical approximation. Both charge and energy transport and their interplay can be studied. We compare the MD results with those of a fully quantum mechanical nonequilibrium Green's function (NEGF) approach for the electron currents. We find a ballistic to diffusive transition of the electron conduction in one...
Effect of doping on lattice dynamics and electron-phonon coupling of the actinides Ac-Th alloy.
de Coss-Martínez, R; González-Castelazo, P; De la Peña-Seaman, O; Heid, R; Bohnen, K-P
2017-09-06
We have studied the electronic, lattice dynamical, and electron-phonon properties of the actinides [Formula: see text]Th x alloy within the framework of density functional perturbation theory. The self-consistent virtual crystal approximation is used for the alloy modeling, and spin-orbit coupling is included in the calculation of all relevant quantities. An overall decrease of the electron-phonon coupling (λ) by [Formula: see text] from Ac to Th was observed. However, its dependence on x shows a non-linear behavior. λ reduces just 6% from Ac to a Th content of [Formula: see text], then drops drastically (∼[Formula: see text]) from there until [Formula: see text]. The large decrease of λ for [Formula: see text] is due to the reduction of the density of states at the Fermi level ([Formula: see text]), combined with a general phonon hardening. On contrast, the behavior for [Formula: see text] is the result of a subtle balance between an enhancement of phase space and the above mentioned effects on [Formula: see text] and the phonons. The phase-space enhancement is related to the appearance of Kohn anomalies, which fade away as the Th concentration increases.
Lattice dynamics and electron-phonon coupling on Mn1-xFexSi: effect of magnetism
Gonzalez Castelazo, Paola; de La Peã+/-A Seaman, Omar; Heid, Rolf; Bohnen, Klaus-Peter
We have studied the electronic, lattice dynamics, and electron-phonon (e-ph) coupling properties of the Mn1-xFexSi alloy. This system have been analyzed within the framework of density functional perturbation theory, using a mixed-basis pseudopotential method and the virtual crystal approximation (VCA) for modeling the alloy. In particular, the electronic density of states (DOS), the full-phonon dispersion, as well as the electron-phonon coupling (λ) and the phonon linewidth (γ) have been calculated with and without the inclusion of spin polarization. While for FeSi is very well known that the effects of magnetism on the lattice dynamics are observed trough the phonon linewidths for specific regions on the zone boundary, on MnSi such detail analysis has not been addressed so far. Thus, the evolution of phonon frequencies and linewidths as a function of Fe-content are presented and discussed in detail, paying special attention the effect of spin-polarization on such properties for the magnetic region on the phase diagram x Conacyt-México under project No. CB2013-221807-F.
Energy Technology Data Exchange (ETDEWEB)
Glinka, Yuri D., E-mail: ydglinka@mail.wvu.edu [Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506-6315 (United States); Institute of Physics, National Academy of Sciences of Ukraine, Kiev 03028 (Ukraine); Babakiray, Sercan; Lederman, David [Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506-6315 (United States)
2015-10-07
Raman measurements of a Fano-type surface phonon mode associated with Dirac surface states (SS) in Bi{sub 2}Se{sub 3} topological insulator thin films allowed an unambiguous determination of the electron-phonon coupling strength in Dirac SS as a function of film thickness ranging from 2 to 40 nm. A non-monotonic enhancement of the electron-phonon coupling strength with maximum for the 8–10 nm thick films was observed. The non-monotonicity is suggested to originate from plasmon-phonon coupling which enhances electron-phonon coupling when free carrier density in Dirac SS increases with decreasing film thickness and becomes suppressed for thinnest films when anharmonic coupling between in-plane and out-of-plane phonon modes occurs. The observed about four-fold enhancement of electron-phonon coupling in Dirac SS of the 8–10 nm thick Bi{sub 2}Se{sub 3} films with respect to the bulk samples may provide new insights into the origin of superconductivity in this-type materials and their applications.
Energy Technology Data Exchange (ETDEWEB)
Maschek, M.; Rosenkranz, S.; Heid, R.; Said, A. H.; Giraldo-Gallo, P.; Fisher, I. R.; Weber, F.
2015-06-01
We present a high-energy-resolution inelastic x-ray scattering investigation of the soft phonon mode in the charge-density-wave (CDW) system TbTe3. We analyze our data based on lattice dynamical calculations using density-functional-perturbation theory and find clear evidence that strongly momentum-dependent electron-phonon coupling defines the periodicity of the CDW superstructure: Our experiment reveals strong phonon softening and increased phonon linewidths over a large part in reciprocal space adjacent to the CDW ordering vector q(CDW) = (0,0,0.3). Further, q(CDW) is clearly offset from the wave vector of (weak) Fermi surface nesting q(FS) = (0,0,0.25), and our detailed analysis indicates that electron-phonon coupling is responsible for this shift. Hence, we can add TbTe3, which was previously considered as a canonical CDW compound following the Peierls scenario, to the list of distinct charge-density-wave materials characterized by momentum-dependent electron-phonon coupling.
Lu, Zexi; Wang, Yan; Ruan, Xiulin
2016-02-01
The standard two-temperature equations for electron-phonon coupled thermal transport across metal/nonmetal interfaces are modified to include the possible coupling between metal electrons with substrate phonons. The previous two-temperature molecular dynamics (TT-MD) approach is then extended to solve these equations numerically at the atomic scale, and the method is demonstrated using Cu/Si interface as an example. A key parameter in TT-MD is the nonlocal coupling distance of metal electrons and nonmetal phonons, and here we use two different approximations. The first is based on Overhauser's "joint-modes" concept, while we use an interfacial reconstruction region as the length scale of joint region rather than the phonon mean-free path as in Overhauser's original model. In this region, the metal electrons can couple to the joint phonon modes. The second approximation is the "phonon wavelength" concept where electrons couple to phonons nonlocally within the range of one phonon wavelength. Compared with the original TT-MD, including the cross-interface electron-phonon coupling can slightly reduce the total thermal boundary resistance. Whether the electron-phonon coupling within the metal block is nonlocal or not does not make an obvious difference in the heat transfer process. Based on the temperature profiles from TT-MD, we construct a new mixed series-parallel thermal circuit. We show that such a thermal circuit is essential for understanding metal/nonmetal interfacial transport, while calculating a single resistance without solving temperature profiles as done in most previous studies is generally incomplete. As a comparison, the simple series circuit that neglects the cross-interface electron-phonon coupling could overestimate the interfacial resistance, while the simple parallel circuit in the original Overhauser's model underestimates the total interfacial resistance.
Resonant supercollisions and electron-phonon heat transfer in graphene
Tikhonov, K. S.; Gornyi, I. V.; Kachorovskii, V. Yu.; Mirlin, A. D.
2018-02-01
We study the effects of strong impurities on heat transfer in a coupled electron-phonon system in disordered graphene. A detailed analysis of the electron-phonon heat exchange assisted by such an impurity through the "resonant supercollision" mechanism is presented. We further explore the local modification of heat transfer in a weakly disordered graphene due to a resonant scatterer and determine spatial profiles of the phonon and electron temperature around the scatterer under electrical driving. Our results are consistent with recent experimental findings on imaging resonant dissipation from individual atomic defects.
Binder, J.; Urban, J. M.; Stepniewski, R.; Strupinski, W.; Wysmolek, A.
2014-01-01
We present a novel measurement approach which combines the electrical characterization of solution-gated field effect transistors based on epitaxial bilayer graphene on 4H-SiC (0001) with simultaneous Raman spectroscopy. By changing the gate voltage, we observed Raman signatures related to the resonant electron-phonon coupling. An analysis of these Raman bands enabled the extraction of the geometrical capacitance of the system and an accurate calculation of the Fermi levels for bilayer graphe...
Ienaga, Koichiro; Iimori, Takushi; Yaji, Koichiro; Miyamachi, Toshio; Nakashima, Shuhei; Takahashi, Yukio; Fukuma, Kohei; Hayashi, Shingo; Kajiwara, Takashi; Visikovskiy, Anton; Mase, Kazuhiko; Nakatsuji, Kan; Tanaka, Satoru; Komori, Fumio
2017-06-14
Local electron-phonon coupling of a one-dimensionally nanorippled graphene is studied on a SiC(0001) vicinal substrate. We have characterized local atomic and electronic structures of a periodically nanorippled graphene (3.4 nm period) prepared on a macrofacet of the 6H-SiC crystal using scanning tunneling microscopy/spectroscopy (STM/STS) and angle-resolved photoelectron spectroscopy (ARPES). The rippled graphene on the macrofacets distributes homogeneously over the 6H-SiC substrate in a millimeter scale, and thus replica bands are detected by the macroscopic ARPES. The STM/STS results indicate the strength of electron-phonon coupling to the out-of-plane phonon at the K̅ points of graphene is periodically modified in accordance with the ripple structure. We propose an interface carbon nanostructure with graphene nanoribbons between the surface rippled graphene and the substrate SiC that periodically modifies the electron-phonon coupling in the surface graphene.
de La Peña Seaman, Omar; de Coss-Martinez, Romeo; Gonzalez-Castelazo, Paola; Heid, Rolf; Bohnen, Klaus-Peter
We have studied the electronic, lattice dynamics, and electron-phonon (e-ph) properties of the Ac1-xThx actinide alloy. This system have been studied within the framework of density functional perturbation theory, using a mixed-basis pseudopotential method and the virtual crystal approximation (VCA) for modeling the alloy. The electronic density of states (DOS), the full-phonon dispersion as well as the Eliashberg spectral function (α2 F (ω)) and the electron-phonon coupling (λ) parameter have been calculated with and without the inclusion of spin-orbit coupling (SOC). For Ac the observed effects of SOC on α2 F (ω) are very minor. However, as Th-content increases on the alloy the SOC influence is more important. Such evolution has its roots on a continuous increase of density of states at the Fermi level (N (EF)) difference between schemes, as well as a steady hardening of the SOC full phonon dispersion. The evolution of λ as a function of Th-content for both schemes is presented and discussed on the light of SOC effects on the electronic and vibrational properties. This research was supported by Conacyt-México under Project No. 221807.
Pieper, J K; Renger, G; Schödel, R; Voigt, J
2001-01-01
Line-narrowed and temperature-dependent fluorescence spectra are reported for the solubilized trimeric light-harvesting complex of Photosystem II (LHC II). Special attention has been paid to eliminate effects owing to reabsorption and to ensure that the line-narrowed fluorescence spectra are virtually unaffected by hole burning or scattering artifacts. Analysis of line-narrowed fluorescence spectra at 4.2 K indicates that the lowest Q//y-state of LHC II is characterized by weak electron-phonon coupling with a Huang-Rhys factor of similar to 0.9 and a broad and strongly asymmetric one- phonon profile with a peak frequency omega//m of 15 cm**-**1 and a width of Gamma = 105 cm**-**1. The 4.2 K fluorescence data are further consistent with the assignment of the lowest Q//y-state at similar to 680.0 nm and an inhomogeneous width of similar to 80 cm**- **1 gathered from a recent hole-burning study (Pieper et al. J. Phys. Chem. A 1999, 103, 2412). The temperature dependence of the fluorescence spectra of LHC II is s...
Energy Technology Data Exchange (ETDEWEB)
Spann, B. T.; Xu, X., E-mail: xxu@purdue.edu [School of Mechanical Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States)
2014-08-25
We employ ultrafast transient absorption spectroscopy with temporal pulse shaping to manipulate coherent phonon excitation and quantify the strength of electron-phonon coupling in CdTe{sub 1−x}Se{sub x} nanocrystals (NCs). Raman active CdSe and CdTe longitudinal optical phonon (LO) modes are excited and probed in the time domain. By temporally controlling pump pulse pairs to coherently excite and cancel coherent phonons in the CdTe{sub 1−x}Se{sub x} NCs, we estimate the relative amount of optical energy that is coupled to the coherent CdSe LO mode.
Directory of Open Access Journals (Sweden)
Carmine Antonio Perroni
2014-03-01
Full Text Available Spectral and transport properties of small molecule single-crystal organic semiconductors have been theoretically analyzed focusing on oligoacenes, in particular on the series from naphthalene to rubrene and pentacene, aiming to show that the inclusion of different electron-phonon couplings is of paramount importance to interpret accurately the properties of prototype organic semiconductors. While in the case of rubrene, the coupling between charge carriers and low frequency inter-molecular modes is sufficient for a satisfactory description of spectral and transport properties, the inclusion of electron coupling to both low-frequency inter-molecular and high-frequency intra-molecular vibrational modes is needed to account for the temperature dependence of transport properties in smaller oligoacenes. For rubrene, a very accurate analysis in the relevant experimental configuration has allowed for the clarification of the origin of the temperature-dependent mobility observed in these organic semiconductors. With increasing temperature, the chemical potential moves into the tail of the density of states corresponding to localized states, but this is not enough to drive the system into an insulating state. The mobility along different crystallographic directions has been calculated, including vertex corrections that give rise to a transport lifetime one order of magnitude smaller than the spectral lifetime of the states involved in the transport mechanism. The mobility always exhibits a power-law behavior as a function of temperature, in agreement with experiments in rubrene. In systems gated with polarizable dielectrics, the electron coupling to interface vibrational modes of the gate has to be included in addition to the intrinsic electron-phonon interaction. While the intrinsic bulk electron-phonon interaction affects the behavior of mobility in the coherent regime below room temperature, the coupling with interface modes is dominant for the
DEFF Research Database (Denmark)
Nielsen, Per Kær; Nielsen, Torben Roland; Lodahl, Peter
2010-01-01
treatments. A pronounced consequence is the emergence of a phonon induced spectral asymmetry when detuning the cavity from the quantum-dot resonance. The asymmetry can only be explained when considering the polaritonic quasiparticle nature of the quantum-dot-cavity system. Furthermore, a temperature induced......We investigate the influence of electron-phonon interactions on the dynamical properties of a quantum-dot-cavity QED system. We show that non-Markovian effects in the phonon reservoir lead to strong changes in the dynamics, arising from photon-assisted dephasing processes, not present in Markovian...
Energy Technology Data Exchange (ETDEWEB)
Borca, C. N.; Adenwalla, S.; Choi, J.; Robertson, L.; You, H.; Fridkin, V. M.; Palto, S. P.; Petukhova, N.; Ducharme, S.; Dowben, P. A.
2000-11-08
We present evidence for a change in electron--phonon coupling across a bulk phase transition. Below the lattice stiffening transition at around 160 K, there is a change in the diffracted peak width observed by neutron and X-ray scattering techniques. Also, the electronic band structure of the copolymer is shifting in binding energy below 160 K, decreasing the density of states near the Fermi level. The value of the effective Debye temperature above the transition temperature is approximately 50 K, while below 160 K, the value of the Debye parameter is 245 K. We postulate that the coupling between electrons and phonons results in a static distortion of the lattice (below 160 K), and this distortion ''melts'' above 160 K.
Theory of parametrically amplified electron-phonon superconductivity
Babadi, Mehrtash; Knap, Michael; Martin, Ivar; Refael, Gil; Demler, Eugene
2017-07-01
Ultrafast optical manipulation of ordered phases in strongly correlated materials is a topic of significant theoretical, experimental, and technological interest. Inspired by a recent experiment on light-induced superconductivity in fullerenes [M. Mitrano et al., Nature (London) 530, 461 (2016), 10.1038/nature16522], we develop a comprehensive theory of light-induced superconductivity in driven electron-phonon systems with lattice nonlinearities. In analogy with the operation of parametric amplifiers, we show how the interplay between the external drive and lattice nonlinearities lead to significantly enhanced effective electron-phonon couplings. We provide a detailed and unbiased study of the nonequilibrium dynamics of the driven system using the real-time Green's function technique. To this end, we develop a Floquet generalization of the Migdal-Eliashberg theory and derive a numerically tractable set of quantum Floquet-Boltzmann kinetic equations for the coupled electron-phonon system. We study the role of parametric phonon generation and electronic heating in destroying the transient superconducting state. Finally, we predict the transient formation of electronic Floquet bands in time- and angle-resolved photoemission spectroscopy experiments as a consequence of the proposed mechanism.
Onda, Ken; Ogihara, Sho; Yonemitsu, Kenji; Maeshima, Nobuya; Ishikawa, Tadahiko; Okimoto, Yoichi; Shao, Xiangfeng; Nakano, Yoshiaki; Yamochi, Hideki; Saito, Gunzi; Koshihara, Shin-Ya
2008-08-01
The quasistable state in the photoinduced phase transition for the quasi-one-dimensional quarter-filled organic conductor (EDO-TTF)2PF6 has been examined by ultrafast reflective measurements and time-dependent model calculations incorporating both electron-electron and electron-phonon interactions. The transient optical conductivity spectrum over a wide probe photon-energy range revealed that photoexcitation induced a new type of charge-disproportionate state. Additionally, coherent and incoherent oscillations dependent on probe photon energies were found, as predicted by the calculation.
Choi, Seokhwan; Johnston, Steven; Jang, Won-Jun; Koepernik, Klaus; Nakatsukasa, Ken; Ok, Jong Mok; Lee, Hyun-Jung; Choi, Hyun Woo; Lee, Alex Taekyung; Akbari, Alireza; Semertzidis, Yannis K.; Bang, Yunkyu; Kim, Jun Sung; Lee, Jhinhwan
2017-09-01
Interfacial phonons between iron-based superconductors (FeSCs) and perovskite substrates have received considerable attention due to the possibility of enhancing preexisting superconductivity. Using scanning tunneling spectroscopy, we studied the correlation between superconductivity and e -ph interaction with interfacial phonons in an iron-based superconductor Sr2VO3FeAs (Tc≈33 K ) made of alternating FeSC and oxide layers. The quasiparticle interference measurement over regions with systematically different average superconducting gaps due to the e -ph coupling locally modulated by O vacancies in the VO2 layer, and supporting self-consistent momentum-dependent Eliashberg calculations provide a unique real-space evidence of the forward-scattering interfacial phonon contribution to the total superconducting pairing.
Ziaei, Vafa; Bredow, Thomas
2017-06-01
We study the impact of dynamical electron-phonon (el-ph) effects on the electronic band gap of ice and liquid water by accounting for frequency-dependent Fan contributions in the el-ph mediated self-energy within the many-body perturbation theory (MBPT). We find that the dynamical el-ph coupling effects greatly reduce the static el-ph band-gap correction of the hydrogen-rich molecular ice crystal from-2.46 to -0.23 eV in great contrast to the result of Monserrat et al. [Phys. Rev. B 92, 140302 (2015), 10.1103/PhysRevB.92.140302]. This is of particular importance as otherwise the static el-ph gap correction would considerably reduce the electronic band gap, leading to considerable underestimation of the intense peaks of optical absorption spectra of ice which would be in great disagreement to experimental references. By contrast, the static el-ph gap correction of liquid water is very moderate (-0.32 eV), and inclusion of dynamical effects slightly reduces the gap correction to -0.19 eV. Further, we determine the diverse sensitivity of ice and liquid water to the G W self-consistency and show that the energy-only self-consistent approach (GnWn ) exhibits large implicit vertex character in comparison to the quasiparticle self-consistent approach, for which an explicit calculation of vertex corrections is necessary for good agreement with experiment.
Wang, Y.; Nakatsukasa, K.; Rademaker, L.; Berlijn, T.; Johnston, S.
2016-05-01
Mono- and multilayer FeSe thin films grown on SrTiO3 and BiTiO3 substrates exhibit a greatly enhanced superconductivity over that found in bulk FeSe. A number of proposals have been advanced for the mechanism of this enhancement. One possibility is the introduction of a cross-interface electron-phonon (e-ph) interaction between the FeSe electrons and oxygen phonons in the substrates that is peaked in the forward scattering (small {q}) direction due to the two-dimensional nature of the interface system. Motivated by this, we explore the consequences of such an interaction on the superconducting state and electronic structure of a two-dimensional system using Migdal-Eliashberg (ME) theory. This interaction produces not only deviations from the expectations of conventional phonon-mediated pairing but also replica structures in the spectral function and density of states, as probed by angle-resolved photoemission spectroscopy, scanning tunneling microscopy/spectroscopy, and quasiparticle interference imaging. We also discuss the applicability of ME theory for a situation where the e-ph interaction is peaked at small momentum transfer and in the FeSe/STO system.
International Nuclear Information System (INIS)
Säkkinen, Niko; Leeuwen, Robert van; Peng, Yang; Appel, Heiko
2015-01-01
We study ground-state properties of a two-site, two-electron Holstein model describing two molecules coupled indirectly via electron-phonon interaction by using both exact diagonalization and self-consistent diagrammatic many-body perturbation theory. The Hartree and self-consistent Born approximations used in the present work are studied at different levels of self-consistency. The governing equations are shown to exhibit multiple solutions when the electron-phonon interaction is sufficiently strong, whereas at smaller interactions, only a single solution is found. The additional solutions at larger electron-phonon couplings correspond to symmetry-broken states with inhomogeneous electron densities. A comparison to exact results indicates that this symmetry breaking is strongly correlated with the formation of a bipolaron state in which the two electrons prefer to reside on the same molecule. The results further show that the Hartree and partially self-consistent Born solutions obtained by enforcing symmetry do not compare well with exact energetics, while the fully self-consistent Born approximation improves the qualitative and quantitative agreement with exact results in the same symmetric case. This together with a presented natural occupation number analysis supports the conclusion that the fully self-consistent approximation describes partially the bipolaron crossover. These results contribute to better understanding how these approximations cope with the strong localizing effect of the electron-phonon interaction
Electron-phonon interactions and the phonon anomaly in β-phase NiTi
International Nuclear Information System (INIS)
Zhao, G.L.; Harmon, B.N.
1993-01-01
The electronic structure of β-phase NiTi has been calculated using a first-principles linear-combination-of-atomic-orbitals method. The resulting band structure was fitted with a nonorthogonal tight-binding Hamiltonian from which electron-phonon matrix elements were evaluated. The soft phonon near Q 0 =(2/3, 2) / (3 ,0)π/a, which is responsible for the premartensitic phase transition in β-phase NiTi, is found to arise from the strong electron-phonon coupling of nested electronic states on the Fermi surface. Thermal vibrations and changes in electronic occupation cause a smearing of the nested features, which in turn cause a hardening of the phonon anomaly
Energy Technology Data Exchange (ETDEWEB)
Wang, Yan [Univ. of Tennessee, Knoxville, TN (United States); Rademaker, Louk [Univ. of California, Santa Barbara, CA (United States); Dagotto, Elbio R. [Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Johnston, Steven [Univ. of Tennessee, Knoxville, TN (United States)
2017-08-18
Here, the discovery of an enhanced superconducting transition temperature T_{c} in monolayers of FeSe grown on several oxide substrates has opened a new route to high-T_{c} superconductivity through interface engineering. One proposal for the origin of the observed enhancement is an electronphonon (e-ph) interaction across the interface that peaked at small momentum transfers. In this paper, we examine the implications of such a coupling on the phononic properties of the system. We show that a strong forward scattering leads to a sizable broadening of phonon lineshape, which may result in charge instabilities at long-wavelengths. However, we further find that the inclusion of Coulombic screening significantly reduces the phonon broadening. Our results show that one might not expect anomalously broad phonon linewidths in the FeSe interface systems, despite the fact that the e-ph interaction has a strong peak in the forward scattering (small \\bfq ) direction.
Energy Technology Data Exchange (ETDEWEB)
Aperis, Alexandros; Oppeneer, Peter M. [Uppsala University (Sweden)
2016-07-01
A monolayer of FeSe deposited on SrTiO{sub 3} becomes superconducting at temperatures that exceed T{sub c}=100 K, as compared to a bulk T{sub c} of 8 K. Recent ARPES measurements have provided strong evidence that an interfaced-induced electron-phonon interaction between FeSe electrons and SrTiO{sub 3} phonons plays a decisive role in this phenomenon. However, the mechanism that drives this tantalizing high-T{sub c} boost is still unclear. Here, we examine the recent experimental findings using fully anisotropic, full bandwidth multiband Eliashberg calculations focusing on the superconducting state of FeSe/STO. We use a realistic ten band tight-binding band structure for the electrons of monolayer FeSe and study how the suggested interface-induced small-q electron-phonon interaction mediates superconductivity. Our calculations produce a high-T{sub c} s-wave superconducting state with the experimentally resolved momentum dependence. Further, we calculate the normal metal/insulator/superconductor tunneling spectrum and identify fingerprints of the interface-induced phonon mechanism.
Electron-phonon interactions from first principles
Giustino, Feliciano
2017-01-01
This article reviews the theory of electron-phonon interactions in solids from the point of view of ab initio calculations. While the electron-phonon interaction has been studied for almost a century, predictive nonempirical calculations have become feasible only during the past two decades. Today it is possible to calculate from first principles many materials properties related to the electron-phonon interaction, including the critical temperature of conventional superconductors, the carrier mobility in semiconductors, the temperature dependence of optical spectra in direct and indirect-gap semiconductors, the relaxation rates of photoexcited carriers, the electron mass renormalization in angle-resolved photoelectron spectra, and the nonadiabatic corrections to phonon dispersion relations. In this article a review of the theoretical and computational framework underlying modern electron-phonon calculations from first principles as well as landmark investigations of the electron-phonon interaction in real materials is given. The first part of the article summarizes the elementary theory of electron-phonon interactions and their calculations based on density-functional theory. The second part discusses a general field-theoretic formulation of the electron-phonon problem and establishes the connection with practical first-principles calculations. The third part reviews a number of recent investigations of electron-phonon interactions in the areas of vibrational spectroscopy, photoelectron spectroscopy, optical spectroscopy, transport, and superconductivity.
Electron-phonon relaxation and excited electron distribution in gallium nitride
Energy Technology Data Exchange (ETDEWEB)
Zhukov, V. P. [Institute of Solid State Chemistry, Urals Branch of the Russian Academy of Sciences, Pervomayskaya st. 91, Yekaterinburg (Russian Federation); Donostia International Physics Center (DIPC), P. Manuel de Lardizabal 4, 20018 San Sebastian (Spain); Tyuterev, V. G., E-mail: valtyut00@mail.ru [Donostia International Physics Center (DIPC), P. Manuel de Lardizabal 4, 20018 San Sebastian (Spain); Tomsk State Pedagogical University, Kievskaya st. 60, Tomsk (Russian Federation); Tomsk State University, Lenin st. 36, Tomsk (Russian Federation); Chulkov, E. V. [Donostia International Physics Center (DIPC), P. Manuel de Lardizabal 4, 20018 San Sebastian (Spain); Tomsk State University, Lenin st. 36, Tomsk (Russian Federation); Departamento de Fisica de Materiales, Facultad de Ciencias Qumicas, UPV/EHU and Centro de Fisica de Materiales CFM-MPC and Centro Mixto CSIC-UPV/EHU, Apdo. 1072, 20080 San Sebastian (Spain); Echenique, P. M. [Donostia International Physics Center (DIPC), P. Manuel de Lardizabal 4, 20018 San Sebastian (Spain); Departamento de Fisica de Materiales, Facultad de Ciencias Qumicas, UPV/EHU and Centro de Fisica de Materiales CFM-MPC and Centro Mixto CSIC-UPV/EHU, Apdo. 1072, 20080 San Sebastian (Spain)
2016-08-28
We develop a theory of energy relaxation in semiconductors and insulators highly excited by the long-acting external irradiation. We derive the equation for the non-equilibrium distribution function of excited electrons. The solution for this function breaks up into the sum of two contributions. The low-energy contribution is concentrated in a narrow range near the bottom of the conduction band. It has the typical form of a Fermi distribution with an effective temperature and chemical potential. The effective temperature and chemical potential in this low-energy term are determined by the intensity of carriers' generation, the speed of electron-phonon relaxation, rates of inter-band recombination, and electron capture on the defects. In addition, there is a substantial high-energy correction. This high-energy “tail” largely covers the conduction band. The shape of the high-energy “tail” strongly depends on the rate of electron-phonon relaxation but does not depend on the rates of recombination and trapping. We apply the theory to the calculation of a non-equilibrium distribution of electrons in an irradiated GaN. Probabilities of optical excitations from the valence to conduction band and electron-phonon coupling probabilities in GaN were calculated by the density functional perturbation theory. Our calculation of both parts of distribution function in gallium nitride shows that when the speed of the electron-phonon scattering is comparable with the rate of recombination and trapping then the contribution of the non-Fermi “tail” is comparable with that of the low-energy Fermi-like component. So the high-energy contribution can essentially affect the charge transport in the irradiated and highly doped semiconductors.
Strong-coupling approximations
International Nuclear Information System (INIS)
Abbott, R.B.
1984-03-01
Standard path-integral techniques such as instanton calculations give good answers for weak-coupling problems, but become unreliable for strong-coupling. Here we consider a method of replacing the original potential by a suitably chosen harmonic oscillator potential. Physically this is motivated by the fact that potential barriers below the level of the ground-state energy of a quantum-mechanical system have little effect. Numerically, results are good, both for quantum-mechanical problems and for massive phi 4 field theory in 1 + 1 dimensions. 9 references, 6 figures
Wu, Liang; Tse, Wang-Kong; Brahlek, M; Morris, C M; Aguilar, R Valdés; Koirala, N; Oh, S; Armitage, N P
2015-11-20
We have utilized time-domain magnetoterahertz spectroscopy to investigate the low-frequency optical response of the topological insulator Cu_{0.02}Bi_{2}Se_{3} and Bi_{2}Se_{3} films. With both field and frequency dependence, such experiments give sufficient information to measure the mobility and carrier density of multiple conduction channels simultaneously. We observe sharp cyclotron resonances (CRs) in both materials. The small amount of Cu incorporated into the Cu_{0.02}Bi_{2}Se_{3} induces a true bulk insulator with only a single type of conduction with a total sheet carrier density of ~4.9×10^{12}/cm^{2} and mobility as high as 4000 cm^{2}/V·s. This is consistent with conduction from two virtually identical topological surface states (TSSs) on the top and bottom of the film with a chemical potential ~145 meV above the Dirac point and in the bulk gap. The CR broadens at high fields, an effect that we attribute to an electron-phonon interaction. This assignment is supported by an extended Drude model analysis of the zero-field Drude conductance. In contrast, in normal Bi_{2}Se_{3} films, two conduction channels were observed, and we developed a self-consistent analysis method to distinguish the dominant TSSs and coexisting trivial bulk or two-dimensional electron gas states. Our high-resolution Faraday rotation spectroscopy on Cu_{0.02}Bi_{2}Se_{3} paves the way for the observation of quantized Faraday rotation under experimentally achievable conditions to push the chemical potential in the lowest Landau level.
A step closer to visualizing the electron___phonon interplay
Energy Technology Data Exchange (ETDEWEB)
Chen, Y.L.; Lee, W.S.; Shen, Z.X.; /Stanford U., Appl. Phys. Dept. /Stanford U., Phys. Dept. /SLAC, PULSE
2011-01-04
The origin of the very high superconducting transition temperature (Tc) in ceramic copper oxide superconductors is one of the greatest mysteries in modern physics. In the superconducting state, electrons form pairs (known as Cooper pairs) and condense into the superfluid state to conduct electric current with zero resistance. For conventional superconductors, it is well established that the 2 electrons in a Cooper pair are 'bonded' by lattice vibrations (phonons), whereas in high-Tc superconductors, the 'glue' for the Cooper pairs is still under intense discussion. Although the high transition temperature and the unconventional pairing symmetry (d-wave symmetry) have led many researchers to believe that the pairing mechanism results from electron-electron interaction, increasing evidence shows that electron-phonon coupling also significantly influences the low-energy electronic structures and hence may also play an important role in high-Tc superconductivity. In a recent issue of PNAS, Carbone et al. use ultrafast electron diffraction, a recently developed experimental technique, to attack this problem from a new angle, the dynamics of the electronic relaxation process involving phonons. Their results provide fresh evidence for the strong interplay between electronic and atomic degrees of freedom in high-Tc superconductivity. In general, ultrafast spectroscopy makes use of the pump-probe method to study the dynamic process in material. In such experiments, one first shoots an ultrafast (typically 10-100 fs) 'pumping' pulse at the sample to drive its electronic system out of the equilibrium state. Then after a brief time delay ({Delta}t) of typically tens of femtoseconds to tens of picoseconds, a 'probing' pulse of either photons or electrons is sent in to probe the sample's transient state. By varying {Delta}t, one can study the process by which the system relaxes back to the equilibrium state, thus acquiring the related
Dvali, Gia
2009-01-01
We show that whenever a 4-dimensional theory with N particle species emerges as a consistent low energy description of a 3-brane embedded in an asymptotically-flat (4+d)-dimensional space, the holographic scale of high-dimensional gravity sets the strong coupling scale of the 4D theory. This connection persists in the limit in which gravity can be consistently decoupled. We demonstrate this effect for orbifold planes, as well as for the solitonic branes and string theoretic D-branes. In all cases the emergence of a 4D strong coupling scale from bulk holography is a persistent phenomenon. The effect turns out to be insensitive even to such extreme deformations of the brane action that seemingly shield 4D theory from the bulk gravity effects. A well understood example of such deformation is given by large 4D Einstein term in the 3-brane action, which is known to suppress the strength of 5D gravity at short distances and change the 5D Newton's law into the four-dimensional one. Nevertheless, we observe that the ...
Confinement of acoustical modes due to the electron-phonon interaction within 2D-electron gas
International Nuclear Information System (INIS)
Kochelap, V.A.; Gulseren, O.
1992-09-01
We study the confinement of acoustical modes within 2DEG due only to the electron-phonon interaction. The confined modes split out from the bulk phonons even at uniform lattice parameters, when the 2DEG is created by means of modulation doping. The effect is more pronounced when the wave vector q of the modes increases and is maximum at q = 2 k F (k F is the Fermi wave vector). In the case of several electron sheets the additional features of the confinement effect appear. In the limit of the strong electron-phonon coupling and high surface concentration of the electrons the considered system can suffer Peierls-type phase transition. In this case periodical deformation of the lattice and charge density wave are confined within the electron sheet. (author). 18 refs, 2 figs
Stirring Strongly Coupled Plasma
Fadafan, Kazem Bitaghsir; Rajagopal, Krishna; Wiedemann, Urs Achim
2009-01-01
We determine the energy it takes to move a test quark along a circle of radius L with angular frequency w through the strongly coupled plasma of N=4 supersymmetric Yang-Mills (SYM) theory. We find that for most values of L and w the energy deposited by stirring the plasma in this way is governed either by the drag force acting on a test quark moving through the plasma in a straight line with speed v=Lw or by the energy radiated by a quark in circular motion in the absence of any plasma, whichever is larger. There is a continuous crossover from the drag-dominated regime to the radiation-dominated regime. In the crossover regime we find evidence for significant destructive interference between energy loss due to drag and that due to radiation as if in vacuum. The rotating quark thus serves as a model system in which the relative strength of, and interplay between, two different mechanisms of parton energy loss is accessible via a controlled classical gravity calculation. We close by speculating on the implicati...
Unraveling the acoustic electron-phonon interaction in graphene
DEFF Research Database (Denmark)
Kaasbjerg, Kristen; Thygesen, Kristian S.; Jacobsen, Karsten W.
2012-01-01
Using a first-principles approach we calculate the electron-phonon couplings in graphene for the transverse and longitudinal acoustic phonons. Analytic forms of the coupling matrix elements valid in the long-wavelength limit are found to give an almost quantitative description of the first...... that the intrinsic effective acoustic deformation potential of graphene is Ξeff=6.8 eV and that the temperature dependence of the mobility μ~T-α in the Bloch-Gru¨neisen regime increases beyond an α=4 dependence even in the absence of screening when the true coupling matrix elements are considered. The α>4...
Energy Technology Data Exchange (ETDEWEB)
Flach, B.
2000-01-01
This thesis has two topics: One is the investigation of an adsorbate induced phonon anomaly on W(110) and Mo{sub 1-x}Re{sub x}(110) (x = 5, 15, 25%) with inelastic helium atom scattering (HAS). The other one is the study of the growth, morphology and dynamics of ultra-thin lithium films deposited on W(110). In 1992 a giant phonon anomaly was found by J. Luedecke on the hydrogen saturated W(110) and Mo(110) surfaces. The anomaly consists of a deep and sharp indentation in the phonon dispersion curves in which the phonon energy nearly drops to zero ({omega}{sub 1}). In addition, a small and broad dip in the surface Rayleigh mode is observed ({omega}{sub 2}). The anomaly appears in the anti {gamma}-H- as well as in the anti {gamma}-S-direction of the surface Brillouin zone (SBZ). Since its first discovery, numerous other experimental and theoretical studies have followed. In the present work the effects is reinvestigated and experimental parameters, such as the crystal temperature and the incident energy, were changed in order to study their influence on the anomalous phonon behavior. In the case of H/Mo(110) the substrate was changed as well by alloying with small amounts of rhenium. In the present experiments a strong crystal temperature dependence of the {omega}{sub 2}-branch was found which leads to lower energies at the 'dip' for smaller temperatures, while the {omega}{sub 1}-anomaly remains unchanged. Such behavior agrees well with the picture that the {omega}{sub 2}-branch is due to a Kohn anomaly. (orig.)
International Nuclear Information System (INIS)
Chabungbam, Satyananda; Sahariah, Munima B.
2015-01-01
First principles calculation reaffirms the presence of phonon anomaly along [211] direction in Ni 2 FeGa shape memory alloy supporting the experimental findings of J. Q. Li et al. Fermi surface scans have been performed in both austenite and martensite phase to see the possible Fermi nesting features in this alloy. The magnitude of observed Fermi surface nesting vectors in (211) plane exactly match the phonon anomaly wavevectors along [211] direction. Electron-phonon calculation in the austenite phase shows that there is significant electron-phonon coupling in this alloy which might arise out of the lattice coupling between lower acoustic modes and higher optical modes combined with the observed strong Fermi nesting features in the system. - Highlights: • Transverse acoustic (TA 2 ) modes show anomaly along [211] direction in Ni 2 FeGa. • The phonon anomaly wavevector has been correlated with the Fermi nesting vectors. • Electron-phonon coupling calculation shows significant coupling in this system. • Max. el-ph coupling occurs in transition frequencies from acoustic to optical modes
Electron-phonon interaction in high temperature superconductors
Directory of Open Access Journals (Sweden)
H. Khosroabadi
2006-09-01
Full Text Available We explore the important role of the strong electron-phonon interaction in high temperature superconductivity through the study of the results of some important experiments, such as inelastic neutron and X-ray scattering, angle resolved photoemission spectroscopy, and isotope effects. We also present our computational results of the eigenvalues and eigenvectors of the Ag Raman modes, and the ionic displacement dependence of the electronic band structure by density functional theory. It is clearly evident that the role of phonons in the mechanism behind the high-temperature superconducting state should be seriously considered.
International Nuclear Information System (INIS)
Aoki, Ken-ichi
1988-01-01
Existence of a strong coupling phase in QED has been suggested in solutions of the Schwinger-Dyson equation and in Monte Carlo simulation of lattice QED. In this article we recapitulate the previous arguments, and formulate the problem in the modern framework of the renormalization theory, Wilsonian renormalization. This scheme of renormalization gives the best understanding of the basic structure of a field theory especially when it has a multi-phase structure. We resolve some misleading arguments in the previous literature. Then we set up a strategy to attack the strong phase, if any. We describe a trial; a coupled Schwinger-Dyson equation. Possible picture of the strong coupling phase QED is presented. (author)
The lattice dynamical studies of rare earth compounds: electron-phonon interactions
International Nuclear Information System (INIS)
Jha, Prafulla K.; Sanyal, Sankar P.; Singh, R.K.
2002-01-01
During the last two decades chalcogenides and pnictides of rare earth (RE) atoms have drawn considerable attention of the solid state physicists because of their peculiar electronic, magnetic, optical and phonon properties. Some of these compounds e.g. sulphides and selenides of cerium (Ce), samarium (Sm), yttrium (Y), ytterbium (Yb), europium (Eu) and thulium (Tm) and their alloys show nonintegral valence (between 2 and 3), arising due to f-d electron hybridization at ambient temperature and pressure. The rare earth mixed valence compounds (MVC) reviewed in this article crystallize in simple cubic structure. Most of these compounds show the existence of strong electron-phonon coupling at half way to the zone boundary. This fact manifests itself through softening of the longitudinal acoustic mode, negative value of elastic constant C 12 etc. The purpose of this contribution is to review some of the recent activities in the fields of lattice dynamics and allied properties of rare earth compounds. The present article is primarily devoted to review the effect of electron-phonon interactions on the dynamical properties of rare earth compounds by using the lattice dynamical model theories based on charged density deformations and long-range many body forces. While the long range charge transfer effect arises due to f-d hybridization of nearly degenerate 4f-5d bands of rare earth ions, the density deformation comes into the picture of breathing motion of electron shells. These effects of charge transfer and charge density deformation when considered in the lattice dynamical models namely the three body force rigid ion model (TRM) and breathing shell model (BSM) are quite successful in explaining the phonon anomalies in these compounds and undoubtedly unraveled many important physical process governing the phonon anomalies in rare earth compounds
Physics of Strongly Coupled Plasma
Energy Technology Data Exchange (ETDEWEB)
Kraeft, Wolf-Dietrich [Universitat Rostock (Germany)
2007-07-15
Strongly coupled plasmas (or non-ideal plasmas) are multi-component charged many-particle systems, in which the mean value of the potential energy of the system is of the same order as or even higher than the mean value of the kinetic energy. The constituents are electrons, ions, atoms and molecules. Dusty (or complex) plasmas contain still mesoscopic (multiply charged) particles. In such systems, the effects of strong coupling (non-ideality) lead to considerable deviations of physical properties from the corresponding properties of ideal plasmas, i.e., of plasmas in which the mean kinetic energy is essentially larger than the mean potential energy. For instance, bound state energies become density dependent and vanish at higher densities (Mott effect) due to the interaction of the pair with the surrounding particles. Non-ideal plasmas are of interest both for general scientific reasons (including, for example, astrophysical questions), and for technical applications such as inertially confined fusion. In spite of great efforts both experimentally and theoretically, satisfactory information on the physical properties of strongly coupled plasmas is not at hand for any temperature and density. For example, the theoretical description of non-ideal plasmas is possible only at low densities/high temperatures and at extremely high densities (high degeneracy). For intermediate degeneracy, however, numerical experiments have to fill the gap. Experiments are difficult in the region of 'warm dense matter'. The monograph tries to present the state of the art concerning both theoretical and experimental attempts. It mainly includes results of the work performed in famous Russian laboratories in recent decades. After outlining basic concepts (chapter 1), the generation of plasmas is considered (chapter 2, chapter 3). Questions of partial (chapter 4) and full ionization (chapter 5) are discussed including Mott transition and Wigner crystallization. Electrical and
Strongly coupled dust coulomb clusters
International Nuclear Information System (INIS)
Juan Wentau; Lai Yingju; Chen Mingheng; I Lin
1999-01-01
The structures and motions of quasi-2-dimensional strongly coupled dust Coulomb clusters with particle number N from few to hundreds in a cylindrical rf plasma trap are studied and compared with the results from the molecular dynamic simulation using more ideal models. Shell structures with periodic packing in different shells and intershell rotational motion dominated excitations are observed at small N. As N increases, the boundary has less effect, the system recovers to the triangular lattice with isotropic vortex type cooperative excitations similar to an infinite N system except the outer shell region. The above generic behaviors are mainly determined by the system symmetry and agree with the simulation results. The detailed interaction form causes minor effect such as the fine structure of packing
The Electron-Phonon Interaction as Studied by Photoelectron Spectroscopy
International Nuclear Information System (INIS)
Lynch, D.W.
2004-01-01
With recent advances in energy and angle resolution, the effects of electron-phonon interactions are manifest in many valence-band photoelectron spectra (PES) for states near the Fermi level in metals
Asymptotic dependence of Gross–Tulub polaron ground-state energy in the strong coupling region
Directory of Open Access Journals (Sweden)
N.I. Kashirina
2017-12-01
Full Text Available The properties of translationally invariant polaron functional have been investigated in the region of strong and extremely strong coupling. It has been shown that the Gross–Tulub polaron functional obtained earlier using the methods of field theory was derived only for the region , where is the Fröhlich constant of the electron-phonon coupling. Various representations of exact and approximate polaron functionals have been considered. Asymptotic dependences of the polaron energy have been obtained using a functional extending the Gross–Tulub functional to the region of extremely strong coupling. The asymptotic dependence of polaron energies for an extremely strong coupling are (for the one-parameter variational function fk, and (for a two-parameter function . It has been shown that the virial theorem 1:3:4 holds for the two-parameter function . Minimization of the approximate functional obtained by expanding the exact Gross–Tulub functional in a series on leads to a quadratic dependence of the polaron energy. This approximation is justified for . For a two-parameter function , the corresponding dependence has the form . However, the use of approximate functionals, in contrast to the strict variational procedure, when the exact polaron functional varies, does not guarantee obtaining the upper limit for the polaron energy.
Energy Technology Data Exchange (ETDEWEB)
Wu, Liang [Johns Hopkins Univ., Baltimore, MD (United States). The Inst. of Quantum Matter; Tse, Wang-Kong [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Morris, C. M. [Johns Hopkins Univ., Baltimore, MD (United States). The Inst. of Quantum Matter; Brahlek, M. [Rutgers Univ., Piscataway, NJ (United States). Dept. of Physics and Astronomy; Koirala, N. [Rutgers Univ., Piscataway, NJ (United States). Dept. of Physics and Astronomy; Oh, S. [Rutgers Univ., Piscataway, NJ (United States). Dept. of Physics and Astronomy; Armitage, N. P. [Johns Hopkins Univ., Baltimore, MD (United States). The Inst. of Quantum Matter
2015-02-05
We have utilized magneto-optical time-domain spectroscopy to investigate the low frequency optical response of topological insulator Cu_{0.02}Bi_{2}Se_{3} and Bi_{2}Se_{3} films. With both field and frequency depedence, such experiments give sufficient information to measure the mobility and carrier density of multiple conduction channels simultaneously. We observe sharp cyclotron resonances (CRs) in both samples. The small amount of Cu substitution into the Cu_{0.02}Bi_{2}Se_{3} induces a true bulk insulator with only a single conduction channel with total sheet carrier density 4.9 x 10^{12}/cm^{2} and mobility as large as 4000 cm^{2}/V s. This is consistent with pure topological surface state (TSSs) conduction with a chemical potential 150 meV above the Dirac point. Hence, a true topological insulator with an insulating bulk is realized. The CR broadens at high fields, an e ect that we attribute to an electron-phonon interaction. This assignment is supported by an extended Drude model analysis on the zero field data. In contrast to Cu_{0.02}Bi_{2}Se_{3}, two charge channels were observed in normal Bi_{2}Se_{3} films. We demonstrate a method to distinguish between the dominant TSSs and trivial bulk/2DEG states. The dominant channel exhibits a CR with a carrier density of ~2.0 x 10^{13}/cm^{2} and mobility ~3200 cm^{2}/V s, consistent with TSSs with a chemical potential ~350meV above the Dirac point.
Electron-phonon scattering effect on the lattice thermal conductivity of silicon nanostructures.
Fu, Bo; Tang, Guihua; Li, Yifei
2017-11-01
Nanostructuring technology has been widely employed to reduce the thermal conductivity of thermoelectric materials because of the strong phonon-boundary scattering. Optimizing the carrier concentration can not only improve the electrical properties, but also affect the lattice thermal conductivity significantly due to the electron-phonon scattering. The lattice thermal conductivity of silicon nanostructures considering electron-phonon scattering is investigated for comparing the lattice thermal conductivity reductions resulting from nanostructuring technology and the carrier concentration optimization. We performed frequency-dependent simulations of thermal transport systematically in nanowires, solid thin films and nanoporous thin films by solving the phonon Boltzmann transport equation using the discrete ordinate method. All the phonon properties are based on the first-principles calculations. The results show that the lattice thermal conductivity reduction due to the electron-phonon scattering decreases as the feature size of nanostructures goes down and could be ignored at low feature sizes (50 nm for n-type nanowires and 20 nm for p-type nanowires and n-type solid thin films) or a high porosity (0.6 for n-type 500 nm-thick nanoporous thin films) even when the carrier concentration is as high as 10 21 cm -3 . Similarly, the size effect due to the phonon-boundary scattering also becomes less significant with the increase of carrier concentration. The findings provide a fundamental understanding of electron and phonon transports in nanostructures, which is important for the optimization of nanostructured thermoelectric materials.
Large N baryons, strong coupling theory, quarks
International Nuclear Information System (INIS)
Sakita, B.
1984-01-01
It is shown that in QCD the large N limit is the same as the static strong coupling limit. By using the static strong coupling techniques some of the results of large N baryons are derived. The results are consistent with the large N SU(6) static quark model. (author)
Strong Coupling Corrections in Quantum Thermodynamics
Perarnau-Llobet, M.; Wilming, H.; Riera, A.; Gallego, R.; Eisert, J.
2018-03-01
Quantum systems strongly coupled to many-body systems equilibrate to the reduced state of a global thermal state, deviating from the local thermal state of the system as it occurs in the weak-coupling limit. Taking this insight as a starting point, we study the thermodynamics of systems strongly coupled to thermal baths. First, we provide strong-coupling corrections to the second law applicable to general systems in three of its different readings: As a statement of maximal extractable work, on heat dissipation, and bound to the Carnot efficiency. These corrections become relevant for small quantum systems and vanish in first order in the interaction strength. We then move to the question of power of heat engines, obtaining a bound on the power enhancement due to strong coupling. Our results are exemplified on the paradigmatic non-Markovian quantum Brownian motion.
Impurity screening in strongly coupled plasma systems
Kyrkos, S
2003-01-01
We present an overview of the problem of screening of an impurity in a strongly coupled one-component plasma within the framework of the linear response (LR) theory. We consider 3D, 2D and quasi-2D layered systems. For a strongly coupled plasma the LR can be determined by way of the known S(k) structure functions. In general, an oscillating screening potential with local overscreening and antiscreening regions emerges. In the case of the bilayer, this phenomenon becomes global, as overscreening develops in the layer of the impurity and antiscreening in the adjacent layer. We comment on the limitations of the LR theory in the strong coupling situation.
Strong Coupling between Plasmons and Organic Semiconductors
Directory of Open Access Journals (Sweden)
Joel Bellessa
2014-05-01
Full Text Available In this paper we describe the properties of organic material in strong coupling with plasmon, mainly based on our work in this field of research. The strong coupling modifies the optical transitions of the structure, and occurs when the interaction between molecules and plasmon prevails on the damping of the system. We describe the dispersion relation of different plasmonic systems, delocalized and localized plasmon, coupled to aggregated dyes and the typical properties of these systems in strong coupling. The modification of the dye emission is also studied. In the second part, the effect of the microscopic structure of the organics, which can be seen as a disordered film, is described. As the different molecules couple to the same plasmon mode, an extended coherent state on several microns is observed.
Gluon scattering amplitudes at strong coupling
Energy Technology Data Exchange (ETDEWEB)
Alday, Luis F. [Institute for Theoretical Physics and Spinoza Institute, Utrecht University, 3508 TD Utrecht (Netherlands); Maldacena, Juan [School of Natural Sciences, Institute for Advanced Study, Princeton, NJ 08540 (United States)
2007-06-15
We describe how to compute planar gluon scattering amplitudes at strong coupling in N = 4 super Yang Mills by using the gauge/string duality. The computation boils down to finding a certain classical string configuration whose boundary conditions are determined by the gluon momenta. The results are infrared divergent. We introduce the gravity version of dimensional regularization to define finite quantities. The leading and subleading IR divergencies are characterized by two functions of the coupling that we compute at strong coupling. We compute also the full finite form for the four point amplitude and we find agreement with a recent ansatz by Bern, Dixon and Smirnov.
Mobility and bulk electron-phonon interaction in two-dimensional materials
DEFF Research Database (Denmark)
Gunst, Tue; Brandbyge, Mads; Markussen, Troels
2015-01-01
-of-plane modes. However, we find that graphene only has a slightly higher mobility compared to silicene. For MoS2 we obtain several orders of magnitude lower mobilities and in agreement with other recent theoretical results. The simulations illustrate the predictive capabilities of the newly implemented......We present calculations of the phonon-limited mobility in intrinsic n-type monolayer graphene, silicene and MoS2. The material properties, including the electron-phonon interaction, are calculated from first principles. Unlike graphene, the carriers in silicene show strong interaction with the out...
Strong Josephson Coupling in Planar Graphene Junctions
Park, Jinho; Lee, Gil-Ho; Lee, Jae Hyeong; Takane, Yositake; Imura, Ken-Ichiro; Taniguchi, Takashi; Watanabe, Kenji; Lee, Hu-Jong
A recent breakthrough of processing graphene, employing encapsulation by hexagonal boron nitride layers (BGB structure), allows realizing the ballistic carrier transport in graphene. Thereafter, ballistic Josephson coupling has been studied by closely edge-contacted BGB structure with two superconducting electrodes. Here, we report on the strong Josephson coupling with planar graphene junction in truly short and ballistic regime. Our device showed high transmission probability and the junction critical current (IC) oscillating for sweeping the gate voltage along with the normal conductance oscillation (Fabry-Perot oscillations), providing a direct evidence for the ballistic nature of the junction pair current. We also observed the convex-upward shape of decreasing critical currents with increasing temperature, canonical properties of the short Josephson coupling. By fitting these curves into theoretical models, we demonstrate the strong Josephson coupling in our devices, which is also supported by the exceptionally large value of ICRN ( 2 Δ / e RNis the normal resistance).
A strongly coupled quark-gluon plasma
Energy Technology Data Exchange (ETDEWEB)
Shuryak, Edward [Department of Physics and Astronomy, University at Stony Brook, NY 11794 (United States)
2004-08-01
Successful description of robust collective flow phenomena at RHIC by ideal hydrodynamics, recent observations of bound c-barc,q-barq states on the lattice, and other theoretical developments indicate that QGP produced at RHIC, and probably in a wider temperature region T{sub c} < T < 4T{sub c}, is not a weakly coupled quasiparticle gas as believed previously. We discuss how strong the interaction is and why it seems to generate hundreds of binary channels with bound states, surviving well inside the QGP phase. We in particular discuss their effect on pressure and viscosity. We conclude by reviewing the similar phenomena for other 'strongly coupled systems', such as (i) strongly coupled supersymmetric theories studied via Maldacena duality; (ii) trapped ultra-cold atoms with very large scattering length, tuned to Feschbach resonances.
Chaos desynchronization in strongly coupled systems
International Nuclear Information System (INIS)
Wu Ye; Liu Weiqing; Xiao, Jinghua; Zhan Meng
2007-01-01
The dynamics of chaos desynchronization in strongly coupled oscillator systems is studied. We find a new bifurcation from synchronous chaotic state, chaotic short wave bifurcation, i.e. a chaotic desynchronization attractor is new born in the systems due to chaos desynchronization. In comparison with the usual periodic short wave bifurcation, very rich but distinct phenomena are observed
Strong-coupling diffusion in relativistic systems
Indian Academy of Sciences (India)
hanced values needed to interpret the data at higher energies point towards the importance of strong-coupling effects. ... when all secondary particles have been created. For short times in the initial phase ... It is decisive for a proper representation of the available data for relativistic heavy-ion collisions at and beyond SPS.
Strong-coupling diffusion in relativistic systems
Indian Academy of Sciences (India)
Different from the early universe, heavy-ion collisions at very high energies do not reach statistical equilibrium, although thermal models explain many of their features. To account for nonequilibrium strong-coupling effects, a Fokker–Planck equation with time-dependent diffusion coefﬁcient is proposed. A schematic model ...
Strongly coupled semidirect mediation of supersymmetry breaking
International Nuclear Information System (INIS)
Ibe, M.; Izawa, K.-I.; Nakai, Y.
2009-01-01
Strongly coupled semidirect gauge mediation models of supersymmetry breaking through massive mediators with standard-model charges are investigated by means of composite degrees of freedom. Sizable mediation is realized to generate the standard-model gaugino masses for a small mediator mass without breaking the standard-model symmetries.
Patterns of Strong Coupling for LHC Searches
Liu, Da; Rattazzi, Riccardo; Riva, Francesco
2016-11-23
Even though the Standard Model (SM) is weakly coupled at the Fermi scale, a new strong dynamics involving its degrees of freedom may conceivably lurk at slightly higher energies, in the multi TeV range. Approximate symmetries provide a structurally robust context where, within the low energy description, the dimensionless SM couplings are weak, while the new strong dynamics manifests itself exclusively through higher-derivative interactions. We present an exhaustive classification of such scenarios in the form of effective field theories, paying special attention to new classes of models where the strong dynamics involves, along with the Higgs boson, the SM gauge bosons and/or the fermions. The IR softness of the new dynamics suppresses its effects at LEP energies, but deviations are in principle detectable at the LHC, even at energies below the threshold for production of new states. Our construction provides the so far unique structurally robust context where to motivate several searches in Higgs physics, d...
Direct measurement of the electron-phonon relaxation rate in thin copper films
Energy Technology Data Exchange (ETDEWEB)
Taskinen, L.J.; Karvonen, J.T.; Maasilta, I.J. [NanoScience Center, Department of Physics, P.O. Box 35, FIN-40014 University of Jyvaeskylae (Finland); Kivioja, J.M. [Low Temperature Laboratory, Helsinki University of Technology, P.O. Box 2200, 02015 HUT Helsinki (Finland)
2004-11-01
We have used normal metal-insulator-superconductor (NIS) tunnel junction pairs, known as SINIS structures, for ultrasensitive thermometry at sub-Kelvin temperatures. With the help of these thermometers, we have developed an ac-technique to measure the electron-phonon (e-p) scattering rate directly, without any other material or geometry dependent parameters, based on overheating the electron gas. The technique is based on Joule heating the electrons in the frequency range DC-10 MHz, and measuring the electron temperature in DC. Because of the nonlinearity of the electron-phonon coupling with respect to temperature, even the DC response will be affected, when the heating frequency reaches the natural cut-off determined by the e-p scattering rate. Results on thin Cu films show a T{sup 4} behavior for the scattering rate, in agreement with indirect measurement of similar samples and numerical modeling of the non-linear response. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Direct measurement of the electron-phonon relaxation rate in thin metal films
Maasilta, Ilari; Kivioja, Jani
2005-03-01
We have used normal metal-insulator-superconductor (NIS) tunnel junctions for ultrasensitive thermometry at sub-Kelvin temperatures. With the help of these thermometers, we have developed an ac-technique to measure the electron-phonon (e-p) scattering rate directly, without any other material or geometry dependent parameters, based on overheating the electron gas. The technique is based on Joule heating the electrons in the frequency range DC-10 MHz, and measuring the electron temperature in DC. Because of the nonlinearity of the electron-phonon coupling with respect to temperature, even the DC response will be affected, when the heating frequency reaches the natural cut-off determined by the e-p scattering rate. Results on thin Cu films show a T^4 behavior for the scattering rate, in agreement with indirect measurement of similar samples and numerical modeling of the non-linear response.ootnotetextL. J. Taskinen, J. M. Kivioja, J. T. Karvonen, and I. J. Maasilta, phys. stat. sol. (c) 1, 2856 (2004). ,ootnotetextJ. T. Karvonen, L. J. Taskinen, I. J. Maasilta, phys. stat. sol. (c) 1, 2799 (2004).
Strong spin-photon coupling in silicon.
Samkharadze, N; Zheng, G; Kalhor, N; Brousse, D; Sammak, A; Mendes, U C; Blais, A; Scappucci, G; Vandersypen, L M K
2018-03-09
Long coherence times of single spins in silicon quantum dots make these systems highly attractive for quantum computation, but how to scale up spin qubit systems remains an open question. As a first step to address this issue, we demonstrate the strong coupling of a single electron spin and a single microwave photon. The electron spin is trapped in a silicon double quantum dot, and the microwave photon is stored in an on-chip high-impedance superconducting resonator. The electric field component of the cavity photon couples directly to the charge dipole of the electron in the double dot, and indirectly to the electron spin, through a strong local magnetic field gradient from a nearby micromagnet. Our results provide a route to realizing large networks of quantum dot-based spin qubit registers. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.
Strong coupling QED with two fermionic flavors
Energy Technology Data Exchange (ETDEWEB)
Wang, K.C.
1990-11-01
We report the recent results of our simulation of strong coupling QED, with non-compact action, on lattices 10{sup 4} and 16{sup 4}. Since we are dealing with two staggered fermionic flavors, we use hybrid algorithm to do the simulation. In addition to the measurement of the chiral order parameter {l angle}{bar {psi}}{psi}{r angle}, we also measure magnetic monopole susceptibility, {chi}, throughout the region of chiral transition. 6 refs., 6 figs.
Strong coupling analogue of the Born series
International Nuclear Information System (INIS)
Dolinszky, T.
1989-10-01
In a given partial wave, the strength of the centrifugal term to be incorporated into the WKBA solutions in different spatial regions can be adjusted so as to make the first order wave functions everywhere smooth and, in strong coupling, exactly reproduce Quantum Mechanics throughout the space. The relevant higher order approximations supply an absolute convergent series expansion of the exact scattering state. (author) 4 refs.; 2 figs.; 2 tabs
Holographic gauge mediation via strongly coupled messengers
International Nuclear Information System (INIS)
McGuirk, Paul; Shiu, Gary; Sumitomo, Yoske
2010-01-01
We consider a relative of semidirect gauge mediation where the hidden sector exists at large 't Hooft coupling. Such scenarios can be difficult to describe using perturbative field theory methods but may fall into the class of holographic gauge mediation scenarios, meaning that they are amenable to the techniques of gauge/gravity duality. We use a recently found gravity solution to examine one such case, where the hidden sector is a cascading gauge theory resulting in a confinement scale not much smaller than the messenger mass. In the original construction of holographic gauge mediation, as in other examples of semidirect gauge mediation at strong coupling, the primary contributions to visible sector soft terms come from weakly coupled messenger mesons. In contrast to these examples, we describe the dual of a gauge theory where there are significant contributions from scales in which the strongly coupled messenger quarks are the effective degrees of freedom. In this regime, the visible sector gaugino mass can be calculated entirely from holography.
The Dark Side of Strongly Coupled Theories
DEFF Research Database (Denmark)
Kouvaris, Christoforos
2008-01-01
We investigate the constraints of dark matter search experiments on the different candidates emerging from the minimal quasi-conformal strong coupling theory with fermions in the adjoint representation. For one candidate, the current limits of CDMS exclude a tiny window of masses around 120 GeV. We...... also investigate under what circumstances the newly proposed candidate composed of a -2 negatively charged particle and a $^4He^{+2}$ can explain the discrepancy between the results of the CDMS and DAMA experiments. We found that this type of dark matter should give negative results in CDMS, while...
Signature of electron-phonon interaction in high temperature superconductors
Directory of Open Access Journals (Sweden)
Vinod Ashokan
2011-09-01
Full Text Available The theory of thermal conductivity of high temperature superconductors (HTS based on electron and phonon line width (life times formulation is developed with Quantum dynamical approach of Green's function. The frequency line width is observed as an extremely sensitive quantity in the transport phenomena of HTS as a collection of large number of scattering processes. The role of resonance scattering and electron-phonon interaction processes is found to be most prominent near critical temperature. The theory successfully explains the spectacular behaviour of high Tc superconductors in the vicinity of transition temperature. A successful agreement between theory and experiment has been obtained by analyzing the thermal conductivity data for the sample La1.8Sr0.2CuO4 in the temperature range 0 − 200K. The theory is equally and successfully applicable to all other high Tc superconductors.
Strong Coupling Gauge Theories in LHC ERA
Fukaya, H.; Harada, M.; Tanabashi, M.; Yamawaki, K.
2011-01-01
Higgs, or techni-dilaton - composite Higgs near conformality / Koichi Yamawaki -- Phase diagram of strongly interacting theories / Francesco Sannino -- Resizing conformal windows / O. Antipin and K. Tuominen -- Nearly conformal gauge theories on the lattice / Zoltan Fodor ... [et al.] -- Going beyond QCD in lattice gauge theory / G. T. Fleming -- Phases of QCD from small to large N[symbol]: (some) lattice results / A. Deuzeman, E. Pallante and M. P. Lombardo -- Lattice gauge theory and (quasi)-conformal technicolor / D. K. Sinclair and J. B. Kogut -- Study of the running coupling constant in 10-flavor QCD with the Schrodinger functional method / N. Yamada ... [et al.] -- Study of the running coupling in twisted Polyakov scheme / T. Aoyama ... [et al.].Running coupling in strong gauge theories via the lattice / Zoltan Fodor ... [et al.] -- Higgsinoless supersymmetry and hidden gravity / Michael L. Graesser, Ryuichiro Kitano and Masafumi Kurachi -- The latest status of LHC and the EWSB physics / S. Asai -- Continuum superpartners from supersymmetric unparticles / Hsin-Chia Cheng -- Review of minimal flavor constraints for technicolor / Hidenori S. Fukano and Francesco Sannino -- Standard model and high energy Lorentz violation / Damiano Anselmi -- Dynamical electroweak symmetry breaking and fourth family / Michio Hashimoto -- Holmorphic supersymmetric Nambu-Jona-Lasino model and dynamical electroweak symmetry breaking / Dong-Won Jung, Otto C. W. Kong and Jae Sik Lee -- Ratchet model of Baryogenesis / Tatsu Takeuchi, Azusa Minamizaki and Akio Sugamoto -- Classical solutions of field equations in Einstein Gauss-Bonnet gravity / P. Suranyi, C. Vaz and L. C. R. Wijewardhana -- Black holes constitute all dark matter / Paul H. Frampton -- Electroweak precision test and Z [symbol] in the three site Higgsless model / Tomohiro Abe -- Chiral symmetry and BRST symmetry breaking, quaternion reality and the lattice simulation / Sadataka Furui -- Holographic techni-dilaton, or
Strong coupling from the Hubbard model
Minahan, Joseph A.
2006-10-01
It was recently observed that the one-dimensional half-filled Hubbard model reproduces the known part of the perturbative spectrum of planar {\\cal N}=4 super Yang Mills in the SU(2) sector. Assuming that this identification is valid beyond perturbation theory, we investigate the behaviour of this spectrum as the 't Hooft parameter λ becomes large. We show that the full dimension Δ of the Konishi superpartner is the solution of a sixth-order polynomial while Δ for a bare dimension 5 operator is the solution of a cubic. In both cases, the equations can be solved easily as a series expansion for both small and large λ and the equations can be inverted to express λ as an explicit function of Δ. We then consider more general operators and show how Δ depends on λ in the strong coupling limit. We are also able to distinguish those states in the Hubbard model which correspond to the gauge-invariant operators for all values of λ. Finally, we compare our results with known results for strings on AdS5 × S5, where we find agreement for a range of R-charges.
Intense Shock Waves and Strongly Coupled Plasmas
Fortov, Vladimir
2005-07-01
The report presents the recent results of experimental investigations of equations of state, compositions, thermodynamical and transport properties, electrical conductivity and opacity of strongly coupled plasmas generated by intense shock and rarefaction waves. The experimental methods for generation of high energy densities in matter, drivers for shock waves and fast diagnostic tools are discussed. Application of intense shock waves to solid and porous targets generates nonideal plasmas in megabar-gigabar pressure range. Compression of plasma by a series of reverberating shock waves allows us to decrease irreversible heating effects. To increase the irreversibility effects and to generate high temperature plasma states the experiments on shock compression of porous samples (fine metal powder, aerogels) were performed. The adiabatic expansion of matter initially compressed by intense shocks up to megabars allows investigating the intermediate region between the solid and vapor phase of nonideal plasmas, including the metal-insulator transition phase and the high temperature saturation curve with critical points of metals. The shock-wave-induced non-equilibrium phenomena at fast melting, spallation and adiabatic condensation are analyzed in the framework of the interspinodal decomposition model. The spall strength of single and polycrystal metals at extremely fast deformation produced by fast shock waves is discussed. The ``pressure ionization'' phenomena in hydrogen, helium, argon, xenon, krypton, neon, iodine, silica, sulfur, fullerenes, and some metals are analyzed on the base of multiple shock compression experiments. For some simple metals (Li, Na, Ca) the effect of ``dielectrization'' as a result of multiple shock compression are discussed.
Stability of the Bi2Se3(111) topological state: Electron-phonon and electron-defect scattering
DEFF Research Database (Denmark)
Hatch, Richard Cannon; Bianchi, Marco; Guan, Dandan
2011-01-01
by introducing a small concentration of surface defects via ion bombardment. It is found that, in contrast to the bulk states, the topological state can no longer be observed in the photoemission spectra, and this cannot merely be attributed to surface defect-induced momentum broadening....... is possible. The electron-phonon coupling constant is found to be λ = 0.25(5), more than an order of magnitude higher than the corresponding value for intraband scattering in the noble-metal surface states. The stability of the topological state with respect to surface irregularities was also tested...
Kinetic theory for strongly coupled Coulomb systems
Dufty, James; Wrighton, Jeffrey
2018-01-01
The calculation of dynamical properties for matter under extreme conditions is a challenging task. The popular Kubo-Greenwood model exploits elements from equilibrium density-functional theory (DFT) that allow a detailed treatment of electron correlations, but its origin is largely phenomenological; traditional kinetic theories have a more secure foundation but are limited to weak ion-electron interactions. The objective here is to show how a combination of the two evolves naturally from the short-time limit for the generator of the effective single-electron dynamics governing time correlation functions without such limitations. This provides a theoretical context for the current DFT-related approach, the Kubo-Greenwood model, while showing the nature of its corrections. The method is to calculate the short-time dynamics in the single-electron subspace for a given configuration of the ions. This differs from the usual kinetic theory approach in which an average over the ions is performed as well. In this way the effective ion-electron interaction includes strong Coulomb coupling and is shown to be determined from DFT. The correlation functions have the form of the random-phase approximation for an inhomogeneous system but with renormalized ion-electron and electron-electron potentials. The dynamic structure function, density response function, and electrical conductivity are calculated as examples. The static local field corrections in the dielectric function are identified in this way. The current analysis is limited to semiclassical electrons (quantum statistical potentials), so important quantum conditions are excluded. However, a quantization of the kinetic theory is identified for broader application while awaiting its detailed derivation.
Compensating strong coupling with large charge
Energy Technology Data Exchange (ETDEWEB)
Alvarez-Gaume, Luis [Theory Department - CERN,CH-1211 Geneva 23 (Switzerland); Simons Center for Geometry and Physics, State University of New York,Stony Brook, NY-11794-3636 (United States); Loukas, Orestis; Orlando, Domenico; Reffert, Susanne [Albert Einstein Center for Fundamental Physics,Institute for Theoretical Physics, University of Bern,Sidlerstrasse 5, CH-3012 Bern (Switzerland)
2017-04-11
We study some (conformal) field theories with global symmetries in the sector where the value of the global charge Q is large. We find (as expected) that the low energy excitations of this sector are described by the general form of Goldstone’s theorem in the non-relativistic regime. We also derive the unexpected result, first presented in https://www.doi.org/10.1007/JHEP12(2015)071, that the effective field theory describing such sector of fixed Q contains effective couplings λ{sub eff}∼λ{sup b}/Q{sup a}, where λ is the original coupling. Hence, large charge leads to weak coupling. In the last section of the paper we present an outline of how to compute anomalous dimensions of the O(n) model in this limit.
Compensating strong coupling with large charge
Alvarez-Gaume, Luis; Orlando, Domenico; Reffert, Susanne
2017-04-11
We study (conformal) field theories with global symmetries in the sector where the value of the global charge $Q$ is large. We find (as expected) that the low energy excitations of this sector are described by the general form of Goldstone's theorem in the non-relativistic regime. We also derive the unexpected result, first presented in [Hellerman:2015], that the effective field theory describing such sector of fixed $Q$ contains effective couplings $\\lambda_{\\text{eff}}\\sim \\lambda^b /Q^{a}$, where $\\lambda$ is the original coupling. Hence, large charge leads to weak coupling. In the last section of the paper we present an outline of how to compute anomalous dimensions in this limit.
Development of strongly coupled FSI technology involving thin walled structures
CSIR Research Space (South Africa)
Suliman, Ridhwaan
2011-01-01
Full Text Available the most desirable results and is coupled with an in-house fluid-flow solver. The developed technology is evaluated on representative strongly coupled fluid-structure interaction test problems....
Electromagnetic modes in cold magnetized strongly coupled plasmas
Tkachenko, I. M.; Ortner, J.; Rylyuk, V. M.
1999-01-01
The spectrum of electromagnetic waves propagating in a strongly coupled magnetized fully ionized hydrogen plasma is found. The ion motion and damping being neglected, the influence of the Coulomb coupling on the electromagnetic spectrum is analyzed.
Huang, Wen Deng; Bao, Li Fu; Ren, Ya Jie; Yuan, Zhao Lin
2018-04-01
The properties of interface optical phonons and their electron-phonon interactions in ZnS/CdS multi-shell spherical quantum dots are studied by adopting dielectric continuum model. The dispersion curves and electron-phonon coupling strengths for interface optical phonons in ZnS/CdS multi-shell dots are calculated and analyzed in detail. It is shown that the number of interface optical phonon branches increase with the increase of layers of multi-shell quantum dots. The number of interface optical phonons increase two branches for increasing one layer material. The dispersions of interface optical phonon with low quantum number l are weak. The electron-interface optical phonon interactions are mainly localized at hetero-interfaces. The interface optical phonons with low quantum number l have important contribution to electron-interface optical phonon interactions.
Strongly coupled band in 140Gd
International Nuclear Information System (INIS)
Falla-Sotelo, F.; Oliveira, J.R.B.; Rao, M.N.
2005-01-01
Several high-K states are known to exist in the mass 130-140 region. For the N=74 even-even isotopes, Kπ = 8 - isomers, with lifetimes ranging from ns to ms, are known in 128 Xe, 130 Ba, 132 Ce, 134 Nd, 136 Sm, and 138 Gd[. In 140 Gd, we have observed for the first time a band also based on an Iπ = 8 - state. This could be the first case of a Kπ = 8 - state observed in an N=76 even-even isotope. The systematics of the Kπ = 8 - isomeric states in N=74 isotopes has been studied by A.M. Bruce et al. These states decay towards the K = 0 ground state band, and the transitions are K-forbidden. The 140 Gd case presents strong similarities but also some significant differences with relation to the N=74 isotopes. We propose the same configuration but with larger deformation in 140 Gd
Strongly coupled band in {sup 140}Gd
Energy Technology Data Exchange (ETDEWEB)
Falla-Sotelo, F.; Oliveira, J.R.B.; Rao, M.N. [Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo (Brazil)] (and others)
2005-07-01
Several high-K states are known to exist in the mass 130-140 region. For the N=74 even-even isotopes, K{pi} = 8{sup -} isomers, with lifetimes ranging from ns to ms, are known in {sup 128}Xe, {sup 130}Ba, {sup 132}Ce, {sup 134}Nd, {sup 136}Sm, and {sup 138}Gd[. In {sup 140}Gd, we have observed for the first time a band also based on an I{pi} = 8{sup -} state. This could be the first case of a K{pi} = 8{sup -} state observed in an N=76 even-even isotope. The systematics of the K{pi} = 8{sup -} isomeric states in N=74 isotopes has been studied by A.M. Bruce et al. These states decay towards the K = 0 ground state band, and the transitions are K-forbidden. The {sup 140}Gd case presents strong similarities but also some significant differences with relation to the N=74 isotopes. We propose the same configuration but with larger deformation in {sup 140}Gd.
Shear viscosities of photons in strongly coupled plasmas
Directory of Open Access Journals (Sweden)
Di-Lun Yang
2016-09-01
Full Text Available We investigate the shear viscosity of thermalized photons in the quark gluon plasma (QGP at weak coupling and N=4 super Yang–Mills plasma (SYMP at both strong and weak couplings. We find that the shear viscosity due to the photon–parton scattering up to the leading order of electromagnetic coupling is suppressed when the coupling of the QGP/SYMP is increased, which stems from the blue-shift of the thermal-photon spectrum at strong coupling. In addition, the shear viscosity rapidly increases near the deconfinement transition in a phenomenological model analogous to the QGP.
Synchrotron radiation in strongly coupled conformal field theories
Athanasiou, Christiana; Chesler, Paul M.; Liu, Hong; Nickel, Dominik; Rajagopal, Krishna
2010-01-01
Using gauge/gravity duality, we compute the energy density and angular distribution of the power radiated by a quark undergoing circular motion in strongly coupled ${\\cal N}=4$ supersymmetric Yang-Mills (SYM) theory. We compare the strong coupling results to those at weak coupling, and find the same angular distribution of radiated power, up to an overall prefactor. In both regimes, the angular distribution is in fact similar to that of synchrotron radiation produced by an electron in circula...
Synchrotron radiation in strongly coupled conformal field theories
Athanasiou, Christiana; Chesler, Paul M.; Liu, Hong; Nickel, Dominik; Rajagopal, Krishna
2010-06-01
Using gauge/gravity duality, we compute the energy density and angular distribution of the power radiated by a quark undergoing circular motion in strongly coupled N=4 supersymmetric Yang-Mills theory. We compare the strong coupling results to those at weak coupling, finding them to be very similar. In both regimes, the angular distribution of the radiated power is in fact similar to that of synchrotron radiation produced by an electron in circular motion in classical electrodynamics: the quark emits radiation in a narrow beam along its velocity vector with a characteristic opening angle α˜1/γ. To an observer far away from the quark, the emitted radiation appears as a short periodic burst, just like the light from a lighthouse does to a ship at sea. Our strong coupling results are valid for any strongly coupled conformal field theory with a dual classical gravity description.
Energy Technology Data Exchange (ETDEWEB)
Kemper, A.F. [Department of Physics, North Carolina State University, Raleigh, NC (United States); Sentef, M.A. [Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Hamburg (Germany); Moritz, B. [Stanford Institute for Materials and Energy Sciences (SIMES), SLAC National Accelerator Laboratory, Menlo Park, CA (United States); Devereaux, T.P. [Stanford Institute for Materials and Energy Sciences (SIMES), SLAC National Accelerator Laboratory, Menlo Park, CA (United States); Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA (United States); Freericks, J.K. [Department of Physics, Georgetown University, Washington, DC (United States)
2017-09-15
We review recent work on the theory for pump/probe photoemission spectroscopy of electron-phonon mediated superconductors in both the normal and the superconducting states. We describe the formal developments that allow one to solve the Migdal-Eliashberg theory in nonequilibrium for an ultrashort laser pumping field, and explore the solutions which illustrate the relaxation as energy is transferred from electrons to phonons. We focus on exact results emanating from sum rules and approximate numerical results which describe rules of thumb for relaxation processes. In addition, in the superconducting state, we describe how Anderson-Higgs oscillations can be excited due to the nonlinear coupling with the electric field and describe mechanisms where pumping the system enhances superconductivity. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Near-field strong coupling of single quantum dots.
Groß, Heiko; Hamm, Joachim M; Tufarelli, Tommaso; Hess, Ortwin; Hecht, Bert
2018-03-01
Strong coupling and the resultant mixing of light and matter states is an important asset for future quantum technologies. We demonstrate deterministic room temperature strong coupling of a mesoscopic colloidal quantum dot to a plasmonic nanoresonator at the apex of a scanning probe. Enormous Rabi splittings of up to 110 meV are accomplished by nanometer-precise positioning of the quantum dot with respect to the nanoresonator probe. We find that, in addition to a small mode volume of the nanoresonator, collective coherent coupling of quantum dot band-edge states and near-field proximity interaction are vital ingredients for the realization of near-field strong coupling of mesoscopic quantum dots. The broadband nature of the interaction paves the road toward ultrafast coherent manipulation of the coupled quantum dot-plasmon system under ambient conditions.
Scattering on a nonrelativistic particle in strong coupling theory
International Nuclear Information System (INIS)
Razumov, A.V.
1977-01-01
Interaction of a nonrelativistic particle with a scalar quantum field has been studied in one-dimensional space in the framework of the Bogolyubov's method. An energy spectrum and scattering amplitude on a dressed particle have been obtained for the case of strong coupling up to the zero order over the coupling constant
Electron-phonon heat exchange in quasi-two-dimensional nanolayers
Anghel, Dragos-Victor; Cojocaru, Sergiu
2017-12-01
We study the heat power P transferred between electrons and phonons in thin metallic films deposited on free-standing dielectric membranes. The temperature range is typically below 1 K, such that the wavelengths of the excited phonon modes in the system is large enough so that the picture of a quasi-two-dimensional phonon gas is applicable. Moreover, due to the quantization of the components of the electron wavevectors perpendicular to the metal film's surface, the electrons spectrum forms also quasi two-dimensional sub-bands, as in a quantum well (QW). We describe in detail the contribution to the electron-phonon energy exchange of different electron scattering channels, as well as of different types of phonon modes. We find that heat flux oscillates strongly with thickness of the film d while having a much smoother variation with temperature (Te for the electrons temperature and Tph for the phonons temperature), so that one obtains a ridge-like landscape in the two coordinates, (d, Te) or (d, Tph), with crests and valleys aligned roughly parallel to the temperature axis. For the valley regions we find P ∝ Te3.5 - Tph3.5. From valley to crest, P increases by more than one order of magnitude and on the crests P cannot be represented by a simple power law. The strong dependence of P on d is indicative of the formation of the QW state and can be useful in controlling the heat transfer between electrons and crystal lattice in nano-electronic devices. Nevertheless, due to the small value of the Fermi wavelength in metals, the surface imperfections of the metallic films can reduce the magnitude of the oscillations of P vs. d, so this effect might be easier to observe experimentally in doped semiconductors.
Dispersion, mode-mixing and the electron-phonon interaction in nanostructures
Dyson, A.; Ridley, B. K.
2018-03-01
The electron-phonon interaction with polar optical modes in nanostructures is re-examined in the light of phonon dispersion relations and the role of the Fuchs-Kliewer (FK) mode. At an interface between adjacent polar materials the frequencies of the FK mode are drawn from the dielectric constants of the adjacent materials and are significantly smaller than the corresponding frequencies of the longitudinal optic (LO) modes at the zone centre. The requirement that all polar modes satisfy mechanical and electrical boundary conditions forces the modes to become hybrids. For a hybrid to have both FK and LO components the LO mode must have the FK frequency, which can only come about through the reduction associated with phonon dispersion relations. We illustrate the effect of phonon dispersion relations on the Fröhlich interaction by considering a simple linear-chain model of the zincblende lattice. Optical and acoustic modes become mixed towards short wavelengths in both optical and acoustic branches. A study of GaAs, InP and cubic GaN and AlN shows that the polarity of the optical branch and the acousticity of the acoustic branch are reduced by dispersion in equal measures, but the effect is relatively weak. Coupling coefficients quantifying the strengths of the interaction with electrons for optical and acoustic components of mixed modes in the optical branch show that, in most cases, the polar interaction dominates the acoustic interaction, and it is reduced from the long-wavelength result towards the zone boundary by only a few percent. The effect on the lower-frequency FK mode can be large.
Driven transverse shear waves in a strongly coupled dusty plasma
International Nuclear Information System (INIS)
Bandyopadhyay, P.; Prasad, G.; Sen, A.; Kaw, P.K.
2008-01-01
The linear dispersion properties of transverse shear waves in a strongly coupled dusty plasma are experimentally studied in a DC discharge device by exciting them in a controlled manner with a variable frequency external source. The dusty plasma is maintained in the strongly coupled fluid regime with (1 c ) where Γ is the Coulomb coupling parameter and Γ c is the crystallization limit. A dispersion relation for the transverse waves is experimentally obtained over a frequency range of 0.1 Hz to 2 Hz and found to show good agreement with viscoelastic theoretical results
Electrical resistivity due to electron-phonon scattering in thin gadolinium films
International Nuclear Information System (INIS)
Urbaniak-Kucharczyk, A.
1988-01-01
The contribution to the electrical resistivity due to the electron-phonon scattering for the special case of h.c.p. structure is derived. The numerical results obtained for the case of polycrystalline gadolinum films show the resistivity dependence on the film thickness and the surface properties. (author)
Influence of the electron-phonon iinteraction on phonon heat conduction in a molecular nanowire
Directory of Open Access Journals (Sweden)
Galović Slobodanka P.
2006-01-01
Full Text Available A model for phonon heat conduction in a molecular nanowire is developed. The calculation takes into account modification of the acoustic phonon dispersion relation due to the electron-phonon interaction. The results obtained are compared with models based upon a simpler, Callaway formula.
Integrating out resonances in strongly-coupled electroweak scenarios
Directory of Open Access Journals (Sweden)
Rosell Ignasi
2017-01-01
Full Text Available Accepting that there is a mass gap above the electroweak scale, the Electroweak Effective Theory (EWET is an appropriate tool to describe this situation. Since the EWET couplings contain information on the unknown high-energy dynamics, we consider a generic strongly-coupled scenario of electroweak symmetry breaking, where the known particle fields are coupled to heavier states. Then, and by integrating out these heavy fields, we study the tracks of the lightest resonances into the couplings. The determination of the low-energy couplings (LECs in terms of resonance parameters can be made more precise by considering a proper short-distance behaviour on the Lagrangian with heavy states, since the number of resonance couplings is then reduced. Notice that we adopt a generic non-linear realization of the electroweak symmetry breaking with a singlet Higgs.
Broadband room temperature strong coupling between quantum dots and metamaterials.
Indukuri, Chaitanya; Yadav, Ravindra Kumar; Basu, J K
2017-08-17
Herein, we report the first demonstration of room temperature enhanced light-matter coupling in the visible regime for metamaterials using cooperative coupled quasi two dimensional quantum dot assemblies located at precise distances from the hyperbolic metamaterial (HMM) templates. The non-monotonic variation of the magnitude of strong coupling, manifested in terms of strong splitting of the photoluminescence of quantum dots, can be explained in terms of enhanced LDOS near the surface of such metamaterials as well as the plasmon mediated super-radiance of closely spaced quantum dots (QDs). Our methodology of enhancing broadband, room temperature, light-matter coupling in the visible regime for metamaterials opens up new possibilities of utilising these materials for a wide range of applications including QD based thresholdless nanolasers and novel metamaterial based integrated photonic devices.
Ultrafast control of strong light–matter coupling
Lange, Christoph; Cancellieri, Emiliano; Panna, Dmitry; Whittaker, David M.; Steger, Mark; Snoke, David W.; Pfeiffer, Loren N.; West, Kenneth W.; Hayat, Alex
2018-01-01
We dynamically modulate strong light–matter coupling in a GaAs/AlGaAs microcavity using intense ultrashort laser pulses tuned below the interband exciton energy, which induce a transient Stark shift of the cavity polaritons. For 225-fs pulses, shorter than the cavity Rabi cycle period of 1000 fs, this shift decouples excitons and cavity photons for the duration of the pulse, interrupting the periodic energy exchange between photonic and electronic states. For 1500-fs pulses, longer than the Rabi cycle period, however, the Stark shift does not affect the strong coupling. The two regimes are marked by distinctly different line shapes in ultrafast reflectivity measurements—regardless of the Stark field intensity. The crossover marks the transition from adiabatic to diabatic switching of strong light–matter coupling.
A Hybrid Strong/Weak Coupling Approach to Jet Quenching
Casalderrey-Solana, Jorge; Milhano, José Guilherme; Pablos, Daniel; Rajagopal, Krishna
2014-01-01
We propose and explore a new hybrid approach to jet quenching in a strongly coupled medium. The basis of this phenomenological approach is to treat physics processes at different energy scales differently. The high-$Q^2$ processes associated with the QCD evolution of the jet from production as a single hard parton through its fragmentation, up to but not including hadronization, are treated perturbatively. The interactions between the partons in the shower and the deconfined matter within which they find themselves lead to energy loss. The momentum scales associated with the medium (of the order of the temperature) and with typical interactions between partons in the shower and the medium are sufficiently soft that strongly coupled physics plays an important role in energy loss. We model these interactions using qualitative insights from holographic calculations of the energy loss of energetic light quarks and gluons in a strongly coupled plasma, obtained via gauge/gravity duality. We embed this hybrid model ...
Ideal gas behavior of a strongly coupled complex (dusty) plasma.
Oxtoby, Neil P; Griffith, Elias J; Durniak, Céline; Ralph, Jason F; Samsonov, Dmitry
2013-07-05
In a laboratory, a two-dimensional complex (dusty) plasma consists of a low-density ionized gas containing a confined suspension of Yukawa-coupled plastic microspheres. For an initial crystal-like form, we report ideal gas behavior in this strongly coupled system during shock-wave experiments. This evidence supports the use of the ideal gas law as the equation of state for soft crystals such as those formed by dusty plasmas.
The strong coupling from tau decays without prejudice
Boito, Diogo; Golterman, Maarten; Jamin, Matthias; Mahdavi, Andisheh; Maltman, Kim; Osborne, James; Peris, Santiago
2014-08-01
We review our recent determination of the strong coupling αs from the OPAL data for non-strange hadronic tau decays. We find that αs (mτ2)= 0.325 ± 0.018 using fixed-order perturbation theory, and αs (mτ2)= 0.347 ± 0.025 using contour-improved perturbation theory. At present, these values supersede any earlier determinations of the strong coupling from hadronic tau decays, including those from ALEPH data.
The strong coupling from tau decays without prejudice
Energy Technology Data Exchange (ETDEWEB)
Boito, Diogo [Physik Department T31, Technische Universität München, James-Franck-Straße 1, D-85748 Garching (Germany); Golterman, Maarten [Institut de Física d' Altes Energies, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Barcelona (Spain); Department of Physics and Astronomy, San Francisco State University, San Francisco, CA 94132 (United States); Jamin, Matthias [Institució Catalana de Recerca i Estudis Avançats (ICREA), IFAE, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Barcelona (Spain); Mahdavi, Andisheh [Department of Physics and Astronomy, San Francisco State University, San Francisco, CA 94132 (United States); Maltman, Kim [Department of Mathematics and Statistics, York University, Toronto, ON Canada M3J 1P3 (Canada); CSSM, University of Adelaide, Adelaide, SA 5005 Australia (Australia); Osborne, James [Department of Physics and Astronomy, San Francisco State University, San Francisco, CA 94132 (United States); Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Peris, Santiago [Department of Physics, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Barcelona (Spain)
2014-08-15
We review our recent determination of the strong coupling α{sub s} from the OPAL data for non-strange hadronic tau decays. We find that α{sub s}(m{sub τ}{sup 2})=0.325±0.018 using fixed-order perturbation theory, and α{sub s}(m{sub τ}{sup 2})=0.347±0.025 using contour-improved perturbation theory. At present, these values supersede any earlier determinations of the strong coupling from hadronic tau decays, including those from ALEPH data.
Beyond strong coupling in a massively multimode cavity
Sundaresan, Neereja; Liu, Yanbing; Sadri, Darius; Szocs, Laszlo; Underwood, Devin; Malekakhlagh, Moein; Tureci, Hakan; Houck, Andrew
2015-03-01
We present experiments in a new regime of cavity quantum electrodynamics (cQED), the multimode strong coupling regime, in which the qubit-cavity coupling is comparable to the free spectral range, thus requiring the collective treatment of all modes along with the qubit. Here we show that this regime is accessible in circuit QED by coupling a 90MHz microwave cavity with a transmon qubit, resonant with the 75th harmonic with a coupling strength exceeding 30MHz. When driving this system, we observe multimode fluorescence consistent with cavity-enhanced sideband emission, with unexpected multi-photon processes and the emergence of ultra-narrow linewidths. This multimode coupling opens the door for a wide range of potential experiments, including studying the manifestation of complex many-body phenomena, the breakdown of the rotating wave approximation, and the bridge between discrete and continuous Hilbert spaces.
From strong to ultrastrong coupling in circuit QED architectures
International Nuclear Information System (INIS)
Niemczyk, Thomas
2011-01-01
The field of cavity quantum electrodynamics (cavity QED) studies the interaction between light and matter on a fundamental level: a single atom interacts with a single photon. If the atom-photon coupling is larger than any dissipative effects, the system enters the strong-coupling limit. A peculiarity of this regime is the possibility to form coherent superpositions of light and matter excitations - a kind of 'molecule' consisting of an atomic and a photonic contribution. The novel research field of circuit QED extends cavity QED concepts to solid-state based system. Here, a superconducting quantum bit is coupled to an on-chip superconducting one-dimensional waveguide resonator. Owing to the small mode-volume of the resonant cavity, the large dipole moment of the 'artificial atom' and the enormous engineering potential inherent to superconducting quantum circuits, remarkable atom-photon coupling strengths can be realized. This thesis describes the theoretical framework, the development of fabrication techniques and the implementation of experimental characterization techniques for superconducting quantum circuits for circuit QED applications. In particular, we study the interaction between superconducting flux quantum bits and high-quality coplanar waveguide resonators in the strong-coupling limit. Furthermore, we report on the first experimental realization of a circuit QED system operating in the ultrastrong-coupling regime, where the atom-photon coupling rate reaches a considerable fraction of the relevant system frequencies. In these experiments we could observe phenomena that can not be explained within the renowned Jaynes-Cummings model. (orig.)
Raman scattering with strongly coupled vibron-polaritons
Strashko, Artem; Keeling, Jonathan
2016-08-01
Strong coupling between cavity photons and molecular vibrations can lead to the formation of vibron-polaritons. In a recent experiment with PVAc molecules in a metal-metal microcavity [Shalabney et al., Angew. Chem., Int. Ed. 54, 7971 (2015), 10.1002/anie.201502979], such a coupling was observed to enhance the Raman scattering probability by several orders of magnitude. Inspired by this, we theoretically analyze the effect of strong photon-vibron coupling on the Raman scattering amplitude of organic molecules. This problem has recently been addressed by del Pino, Feist, and Garcia-Vidal [J. Phys. Chem. C 119, 29132 (2015), 10.1021/acs.jpcc.5b11654] using exact numerics for a small number of molecules. In this paper we derive compact analytic results for any number of molecules, also including the ultrastrong-coupling regime. Our calculations predict a division of the Raman signal into upper and lower polariton modes, with some enhancement to the lower polariton Raman amplitude due to the mode softening under strong coupling.
Radial Distribution Functions of Strongly Coupled Two-Temperature Plasmas
Shaffer, Nathaniel R.; Tiwari, Sanat Kumar; Baalrud, Scott D.
2017-10-01
We present tests of three theoretical models for the radial distribution functions (RDFs) in two-temperature strongly coupled plasmas. RDFs are useful in extending plasma thermodynamics and kinetic theory to strong coupling, but they are usually known only for thermal equilibrium or for approximate one-component model plasmas. Accurate two-component modeling is necessary to understand the impact of strong coupling on inter-species transport, e.g., ambipolar diffusion and electron-ion temperature relaxation. We demonstrate that the Seuferling-Vogel-Toeppfer (SVT) extension of the hypernetted chain equations not only gives accurate RDFs (as compared with classical molecular dynamics simulations), but also has a simple connection with the Yukawa OCP model. This connection gives a practical means to recover the structure of the electron background from knowledge of the ion-ion RDF alone. Using the model RDFs in Effective Potential Theory, we report the first predictions of inter-species transport coefficients of strongly coupled plasmas far from equilibrium. This work is supported by NSF Grant No. PHY-1453736, AFSOR Award No. FA9550-16-1-0221, and used XSEDE computational resources.
Numerical experiments on 2D strongly coupled complex plasmas
International Nuclear Information System (INIS)
Hou Lujing; Ivlev, A V; Thomas, H M; Morfill, G E
2010-01-01
The Brownian Dynamics simulation method is briefly reviewed at first and then applied to study some non-equilibrium phenomena in strongly coupled complex plasmas, such as heat transfer processes, shock wave excitation/propagation and particle trapping, by directly mimicking the real experiments.
Dust acoustic solitary and shock waves in strongly coupled dusty ...
Indian Academy of Sciences (India)
mal vortex-like ion distribution and strongly correlated grains in a liquid-like state and discussed about the properties of shock ... shock waves in coupled dusty plasma with Boltzmann distribution of ions. Ghosh et al have studied the effect of ... ues of parameters where the nonlinear term is zero. Also new kind of shock wave.
Weak and strong coupling equilibration in nonabelian gauge theories
Energy Technology Data Exchange (ETDEWEB)
Keegan, Liam [Physics Department, Theory Unit, CERN,CH-1211 Genève 23 (Switzerland); Kurkela, Aleksi [Physics Department, Theory Unit, CERN,CH-1211 Genève 23 (Switzerland); Faculty of Science and Technology, University of Stavanger,4036 Stavanger (Norway); Romatschke, Paul [Department of Physics, 390 UCB, University of Colorado at Boulder,Boulder, CO (United States); Center for Theory of Quantum Matter, University of Colorado,Boulder, Colorado 80309 (United States); Schee, Wilke van der [Center for Theoretical Physics, MIT,Cambridge, MA 02139 (United States); Zhu, Yan [Department of Physics, University of Jyväskyla, P.O. Box 35, FI-40014 University of Jyväskylä (Finland); Helsinki Institute of Physics,P.O. Box 64, 00014 University of Helsinki (Finland)
2016-04-06
We present a direct comparison studying equilibration through kinetic theory at weak coupling and through holography at strong coupling in the same set-up. The set-up starts with a homogeneous thermal state, which then smoothly transitions through an out-of-equilibrium phase to an expanding system undergoing boost-invariant flow. This first apples-to-apples comparison of equilibration provides a benchmark for similar equilibration processes in heavy-ion collisions, where the equilibration mechanism is still under debate. We find that results at weak and strong coupling can be smoothly connected by simple, empirical power-laws for the viscosity, equilibration time and entropy production of the system.
Weak and strong coupling equilibration in nonabelian gauge theories
Keegan, Liam; Romatschke, Paul; van der Schee, Wilke; Zhu, Yan
2016-01-01
We present a direct comparison studying equilibration through kinetic theory at weak coupling and through holography at strong coupling in the same set-up. The set-up starts with a homogeneous thermal state, which then smoothly transitions through an out-of-equilibrium phase to an expanding system undergoing boost-invariant flow. This first apples-to-apples comparison of equilibration provides a benchmark for similar equilibration processes in heavy-ion collisions, where the equilibration mechanism is still under debate. We find that results at weak and strong coupling can be smoothly connected by simple, empirical power-laws for the viscosity, equilibration time and entropy production of the system.
Equilibration and hydrodynamics at strong and weak coupling
van der Schee, Wilke
2017-11-01
We give an updated overview of both weak and strong coupling methods to describe the approach to a plasma described by viscous hydrodynamics, a process now called hydrodynamisation. At weak coupling the very first moments after a heavy ion collision is described by the colour-glass condensate framework, but quickly thereafter the mean free path is long enough for kinetic theory to become applicable. Recent simulations indicate thermalization in a time t ∼ 40(η / s) 4 / 3 / T [L. Keegan, A. Kurkela, P. Romatschke, W. van der Schee, Y. Zhu, Weak and strong coupling equilibration in nonabelian gauge theories, JHEP 04 (2016) 031. arxiv:arXiv:1512.05347, doi:10.1007/JHEP04(2016)031], with T the temperature at that time and η / s the shear viscosity divided by the entropy density. At (infinitely) strong coupling it is possible to mimic heavy ion collisions by using holography, which leads to a dual description of colliding gravitational shock waves. The plasma formed hydrodynamises within a time of 0.41/T recent extension found corrections to this result for finite values of the coupling, when η / s is bigger than the canonical value of 1/4π, which leads to t ∼ (0.41 + 1.6 (η / s - 1 / 4 π)) / T [S. Grozdanov, W. van der Schee, Coupling constant corrections in holographic heavy ion collisions, arxiv:arXiv:1610.08976]. Future improvements include the inclusion of the effects of the running coupling constant in QCD.
Mamo, Kiminad A.
2013-08-01
We calculate the DC conductivity tensor of strongly coupled = 4 super-Yang-Mills (SYM) plasma in a presence of a strong external magnetic field B ≫ T 2 by using its gravity dual and employing both the RG flow approach and membrane paradigm which give the same results. We find that, since the magnetic field B induces anisotropy in the plasma, different components of the DC conductivity tensor have different magnitudes depending on whether its components are in the direction of the magnetic field B. In particular, we find that a component of the DC conductivity tensor in the direction of the magnetic field B increases linearly with B while the other components (which are not in the direction of the magnetic field B) are independent of it. These results are consistent with the lattice computations of the DC conductivity tensor of the QCD plasma in an external magnetic field B. Using the DC conductivity tensor, we calculate the soft or low-frequency thermal photon and dilepton production rates of the strongly coupled = 4 SYM plasma in the presence of the strong external magnetic field B ≫ T 2. We find that the strong magnetic field B enhances both the thermal photon and dilepton production rates of the strongly coupled = 4 SYM plasma in a qualitative agreement with the experimentally observed enhancements at the heavy-ion collision experiments.
Phase diagram of the layered oxide SnO: GW and electron-phonon studies
Chen, Peng-Jen; Jeng, Horng-Tay
2015-11-01
First-principles calculations are performed to study the electronic properties and the electron-phonon interactions of the layered oxide semiconductor SnO. In addition to the high hole mobility that makes SnO a promising material in electronics, it has recently been reported that the semimetallic phase under pressure is superconducting. The superconducting Tc curve exhibits a dome-like feature under pressure and reaches the maximum of 1.4 K at p = 9.2 GPa. Both its crystal structure and the dome-like Tc curve are reminiscent of the Fe-based superconductor FeSe. Motivated by this observation, we investigate the electronic, phonon, and their interactions in SnO using first-principles schemes. GW approximation is adopted to correct the underestimated band gaps, including real and continuous band gaps in the semiconducting and semimetallic phases. The phase diagram showing the semiconductor-to-semimetal transition and the Tc curve has been successfully reproduced. Detailed analysis of the electron-phonon interactions demonstrate the importance of the out-of-plane motions of O atoms and the Sn-s lone pairs for the superconductivity to occur. Our method combining GW and e-ph calculations can be further extended to the study of other materials that undergo insulator-to-superconductor phase transition.
Hydrodynamics of strongly coupled gauge theories from gravity
International Nuclear Information System (INIS)
Benincasa, P.
2007-01-01
In this talk we review some recent developments in the analysis of gauge theories from a holographic perspective. We focus on the transport properties of strongly coupled gauge theories. In particular, we discuss the results for two specific non-conformal models: the N=2* supersymmetric SU(N c ) Yang-Mills theory and the Sakai-Sugimoto model. Finally, we discuss the hydrodynamic picture for the N=4SU(N c ) SYM theory when the leading correction in the inverse 't Hooft coupling is taken into account
Superconducting proximity effect in the strong-coupling limit
International Nuclear Information System (INIS)
Wilvert, W.
1975-01-01
A generalization of the theory of the superconducting proximity effect is presented which takes into account strong-coupling in the superconductors. The results are found to agree with a model of weak-coupled superconductors with differing Debye frequencies which are in proximity. It is found that logarithmic averaging of phonon frequencies is an improvement on the original McMillan theory (1968). Comparison of the theory with data on thin films and on eutectic alloys is found to give good agreement. 19 references
From strong to ultrastrong coupling in circuit QED architectures
Energy Technology Data Exchange (ETDEWEB)
Niemczyk, Thomas
2011-08-10
The field of cavity quantum electrodynamics (cavity QED) studies the interaction between light and matter on a fundamental level: a single atom interacts with a single photon. If the atom-photon coupling is larger than any dissipative effects, the system enters the strong-coupling limit. A peculiarity of this regime is the possibility to form coherent superpositions of light and matter excitations - a kind of 'molecule' consisting of an atomic and a photonic contribution. The novel research field of circuit QED extends cavity QED concepts to solid-state based system. Here, a superconducting quantum bit is coupled to an on-chip superconducting one-dimensional waveguide resonator. Owing to the small mode-volume of the resonant cavity, the large dipole moment of the 'artificial atom' and the enormous engineering potential inherent to superconducting quantum circuits, remarkable atom-photon coupling strengths can be realized. This thesis describes the theoretical framework, the development of fabrication techniques and the implementation of experimental characterization techniques for superconducting quantum circuits for circuit QED applications. In particular, we study the interaction between superconducting flux quantum bits and high-quality coplanar waveguide resonators in the strong-coupling limit. Furthermore, we report on the first experimental realization of a circuit QED system operating in the ultrastrong-coupling regime, where the atom-photon coupling rate reaches a considerable fraction of the relevant system frequencies. In these experiments we could observe phenomena that can not be explained within the renowned Jaynes-Cummings model. (orig.)
Examining Electron-Boson Coupling Using Time-Resolved Spectroscopy
Energy Technology Data Exchange (ETDEWEB)
Sentef, Michael; Kemper, Alexander F.; Moritz, Brian; Freericks, James K.; Shen, Zhi-Xun; Devereaux, Thomas P.
2013-12-26
Nonequilibrium pump-probe time-domain spectroscopies can become an important tool to disentangle degrees of freedom whose coupling leads to broad structures in the frequency domain. Here, using the time-resolved solution of a model photoexcited electron-phonon system, we show that the relaxational dynamics are directly governed by the equilibrium self-energy so that the phonon frequency sets a window for “slow” versus “fast” recovery. The overall temporal structure of this relaxation spectroscopy allows for a reliable and quantitative extraction of the electron-phonon coupling strength without requiring an effective temperature model or making strong assumptions about the underlying bare electronic band dispersion.
QCD and strongly coupled gauge theories: challenges and perspectives
Energy Technology Data Exchange (ETDEWEB)
Brambilla, N.; Vairo, A. [Technische Universitaet Muenchen, Physik Department, Garching (Germany); Eidelman, S. [SB RAS, Budker Institute of Nuclear Physics, Novosibirsk (Russian Federation); Novosibirsk State University, Novosibirsk (Russian Federation); Foka, P. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Gardner, S. [University of Kentucky, Department of Physics and Astronomy, Lexington, KY (United States); Kronfeld, A.S. [Fermi National Accelerator Laboratory, Theoretical Physics Department, Batavia, IL (United States); Alford, M.G.; Schwenzer, K. [Washington University, Department of Physics, St Louis, MO (United States); Alkofer, R. [University of Graz, Graz (Austria); Butenschoen, M. [University of Vienna, Faculty of Physics, Wien (Austria); Cohen, T.D. [University of Maryland, Maryland Center for Fundamental Physics and Department of Physics, College Park, MD (United States); Erdmenger, J. [Max-Planck-Institute for Physics, Munich (Germany); Fabbietti, L. [Technische Universitaet Muenchen, Excellence Cluster ' ' Origin and Structure of the Universe' ' , Garching (Germany); Faber, M.; Hoellwieser, R. [Technische Universitaet Wien, Atominstitut, Vienna (Austria); Goity, J.L. [Hampton University, Hampton, VA (United States); Jefferson Laboratory, Newport News, VA (United States); Ketzer, B. [Technische Universitaet Muenchen, Physik Department, Garching (Germany); Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik, Bonn (Germany); Lin, H.W. [University of Washington, Department of Physics, Seattle, WA (United States); Llanes-Estrada, F.J. [Universidad Complutense de Madrid, Department Fisica Teorica I, Madrid (Spain); Meyer, H.B.; Wittig, H.; Hippel, G.M. von [Johannes Gutenberg-Universitaet Mainz, PRISMA Cluster of Excellence, Institut fuer Kernphysik and Helmholtz Institut Mainz, Mainz (Germany); Pakhlov, P.; Polikarpov, M.I. [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation); Moscow Institute for Physics and Technology, Dolgoprudny (Russian Federation); Pallante, E.; Papadodimas, K. [University of Groningen, Centre for Theoretical Physics, Groningen (Netherlands); Sazdjian, H. [Universite Paris-Sud, Institut de Physique Nucleaire CNRS/IN2P3, Orsay (France); Schmitt, A. [Technische Universitaet Wien, Institut fuer Theoretische Physik, Vienna (Austria); Snow, W.M. [Indiana University, Center for Exploration of Energy and Matter and Department of Physics, Bloomington, IN (United States); Vogt, R. [Lawrence Livermore National Laboratory, Physics Division, Livermore, CA (United States); University of California, Physics Department, Davis, CA (United States); Vuorinen, A. [University of Helsinki, Department of Physics and Helsinki Institute of Physics, Helsinki (Finland); Arnold, P. [University of Virginia, Department of Physics, Charlottesville, VA (United States); Christakoglou, P. [NIKHEF, Amsterdam (Netherlands); Di Nezza, P. [Istituto Nazionale di Fisica Nucleare (INFN), Frascati (Italy); Fodor, Z. [Wuppertal University, Wuppertal (Germany); Eoetvoes University, Budapest (Hungary); Forschungszentrum Juelich, Juelich (Germany); Garcia i Tormo, X. [Universitaet Bern, Albert Einstein Center for Fundamental Physics, Institut fuer Theoretische Physik, Bern (Switzerland); Janik, M.A. [Warsaw University of Technology, Faculty of Physics, Warsaw (Poland); Kalweit, A. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Keane, D. [Kent State University, Department of Physics, Kent, OH (United States); Kiritsis, E. [University of Crete, Crete Center for Theoretical Physics, Department of Physics, Heraklion (Greece); Universite Paris Diderot, Laboratoire APC, Sorbonne Paris-Cite (France); CERN, Theory Group, Physics Department, Geneva 23 (Switzerland); Mischke, A. [Utrecht University, Faculty of Science, Utrecht (Netherlands); Mizuk, R. [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation); Moscow Physical Engineering Institute, Moscow (Russian Federation); Odyniec, G. [Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Pich, A. [Universitat de Valencia, CSIC, IFIC, Valencia (Spain); Pittau, R. [Universidad de Granada, Departamento de Fisica Teorica y del Cosmos y CAFPE, Granada (Spain); Qiu, J.W. [Brookhaven National Laboratory, Physics Department, Upton, NY (United States); Stony Brook University, C.N. Yang Institute for Theoretical Physics and Department of Physics and Astronomy, Stony Brook, NY (United States); Ricciardi, G. [Universita degli Studi di Napoli Federico II, Dipartimento di Fisica, Napoli (Italy); INFN, Napoli (Italy); Salgado, C.A. [Universidade de Santiago de Compostela, Departamento de Fisica de Particulas y IGFAE, Galicia (ES); Stefanis, N.G. [Ruhr-Universitaet Bochum, Institut fuer Theoretische Physik II, Bochum (DE); Zakharov, V.I. [Max-Planck-Institute for Physics, Munich (DE); Institute of Theoretical and Experimental Physics, Moscow (RU); Moscow Institute for Physics and Technology, Dolgoprudny (RU); Far Eastern Federal University, School of Biomedicine, Vladivostok (RU)
2014-10-15
We highlight the progress, current status, and open challenges of QCD-driven physics, in theory and in experiment. We discuss how the strong interaction is intimately connected to a broad sweep of physical problems, in settings ranging from astrophysics and cosmology to strongly coupled, complex systems in particle and condensed-matter physics, as well as to searches for physics beyond the Standard Model. We also discuss how success in describing the strong interaction impacts other fields, and, in turn, how such subjects can impact studies of the strong interaction. In the course of the work we offer a perspective on the many research streams which flow into and out of QCD, as well as a vision for future developments. (orig.)
Strongly coupled gauge theories: What can lattice calculations teach us?
CERN. Geneva
2015-01-01
Electroweak symmetry breaking and the dynamical origin of the Higgs boson are central questions today. Strongly coupled systems predicting the Higgs boson as a bound state of a new gauge-fermion interaction are candidates to describe beyond Standard Model physics. The phenomenologically viable models are strongly coupled, near the conformal boundary, requiring non-perturbative studies to reveal their properties. Lattice studies show that many of the beyond-Standard Model candidates have a relatively light isosinglet scalar state that is well separated from the rest of the spectrum. When the scale is set via the vev of electroweak symmetry breaking, a 2 TeV vector resonance appears to be a general feature of many of these models with several other resonances that are not much heavier.
Measurement of the strong coupling constant using τ decays
Buskulic, D.; Decamp, D.; Goy, C.; Lees, J.-P.; Minard, M.-N.; Mours, B.; Pietrzyk, B.; Alemany, R.; Ariztizabal, F.; Comas, P.; Crespo, J. M.; Delfino, M.; Fernandez, E.; Fernandez-Bosman, M.; Gaitan, V.; Garrido, Ll.; Mattison, T.; Pacheco, A.; Padilla, C.; Pascual, A.; Creanza, D.; de Palma, M.; Farilla, A.; Iaselli, G.; Maggi, G.; Maggi, M.; Natali, S.; Nuzzo, S.; Quattromini, M.; Ranieri, A.; Raso, G.; Romano, F.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Zito, G.; Chai, Y.; Hu, H.; Huang, D.; Huang, X.; Lin, J.; Wang, T.; Xie, Y.; Xu, D.; Xu, R.; Zhang, J.; Zhang, L.; Zhao, W.; Bauerdick, L. A. T.; Blucher, E.; Bonvicini, G.; Boudreau, J.; Casper, D.; Drevermann, H.; Forty, R. W.; Ganis, G.; Gay, C.; Hagelberg, R.; Harvey, J.; Haywood, S.; Hilgart, J.; Jacobsen, R.; Jost, B.; Knobloch, J.; Lehraus, I.; Lohse, T.; Lusiani, A.; Martinez, M.; Mato, P.; Meinhard, H.; Minten, A.; Miotto, A.; Miquel, R.; Moser, H.-G.; Palazzi, P.; Perlas, J. A.; Pusztaszeri, J.-F.; Ranjard, F.; Redlinger, G.; Rolandi, L.; Rothberg, J.; Ruan, T.; Saich, M.; Schlatter, D.; Schmelling, M.; Sefkow, F.; Tejessy, W.; Wachsmuth, H.; Wiedenmann, W.; Wildish, T.; Witzeling, W.; Wotschack, J.; Ajaltouni, Z.; Badaud, F.; Bardadin-Otwinowska, M.; El Fellous, R.; Falvard, A.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Montret, J.-C.; Pallin, D.; Perret, P.; Podlyski, F.; Proriol, J.; Prulhière, F.; Saadi, F.; Fearnley, T.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Møllerud, R.; Nilsson, B. S.; Efthymiopoulos, I.; Kyriakis, A.; Simopoulou, E.; Vayaki, A.; Zachariadou, K.; Badier, J.; Blondel, A.; Bonneaud, G.; Brient, J. C.; Fouque, G.; Orteu, S.; Rougé, A.; Rumpf, M.; Tanaka, R.; Verderi, M.; Videau, H.; Candlin, D. J.; Parsons, M. I.; Veitch, E.; Moneta, L.; Parrini, G.; Corden, M.; Georgiopoulos, C.; Ikeda, M.; Lannutti, J.; Levinthal, D.; Mermikides, M.; Sawyer, L.; Wasserbaech, S.; Antonelli, A.; Baldini, R.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Cerutti, F.; Chiarella, V.; D'Ettorre-Piazzoli, B.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Passalacqua, L.; Pepe-Altarelli, M.; Picchi, P.; Colrain, P.; Ten Have, I.; Lynch, J. G.; Maitland, W.; Morton, W. T.; Raine, C.; Reeves, P.; Scarr, J. M.; Smith, K.; Smith, M. G.; Thompson, A. S.; Turnbull, R. M.; Brandl, B.; Braun, O.; Geweniger, C.; Hanke, P.; Hepp, V.; Kluge, E. E.; Maumary, Y.; Putzer, A.; Rensch, B.; Stahl, A.; Tittel, K.; Wunsch, M.; Belk, A. T.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Cattaneo, M.; Colling, D. J.; Dornan, P. J.; Dugeay, S.; Greene, A. M.; Hassard, J. F.; Lieske, N. M.; Nash, J.; Payne, D. G.; Phillips, M. J.; Sedgbeer, J. K.; Tomalin, I. R.; Wright, A. G.; Girtler, P.; Kneringer, E.; Kuhn, D.; Rudolph, G.; Bowdery, C. K.; Brodbeck, T. J.; Finch, A. J.; Foster, F.; Hughes, G.; Jackson, D.; Keemer, N. R.; Nuttall, M.; Patel, A.; Sloan, T.; Snow, S. W.; Whelan, E. P.; Kleinknecht, K.; Raab, J.; Renk, B.; Sander, H.-G.; Schmidt, H.; Steeg, F.; Walther, S. M.; Wanke, R.; Wolf, B.; Aubert, J.-J.; Bencheikh, A. M.; Benchouk, C.; Bonissent, A.; Carr, J.; Coyle, P.; Drinkard, J.; Etienne, F.; Nicod, D.; Papalexiou, S.; Payre, P.; Roos, L.; Rousseau, D.; Schwemling, P.; Talby, M.; Adlung, S.; Assmann, R.; Bauer, C.; Blum, W.; Brown, D.; Cattaneo, P.; Dehning, B.; Dietl, H.; Dydak, F.; Frank, M.; Halley, A. W.; Lauber, J.; Lütjens, G.; Lutz, G.; Männer, W.; Richter, R.; Rotscheidt, H.; Schröder, J.; Schwarz, A. S.; Settles, R.; Seywerd, H.; Stierlin, U.; Stiegler, U.; Denis, R. St.; Wolf, G.; Boucrot, J.; Callot, O.; Cordier, A.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Jaffe, D. E.; Janot, P.; Kim, D. W.; Le Diberder, F.; Lefrançois, J.; Lutz, A.-M.; Schune, M.-H.; Veillet, J.-J.; Videau, I.; Zhang, Z.; Abbaneo, D.; Bagliesi, G.; Batignani, G.; Bosisio, L.; Bottigli, U.; Bozzi, C.; Calderini, G.; Carpinelli, M.; Ciocci, M. A.; Dell'Orso, R.; Ferrante, I.; Fidecaro, F.; Foà, L.; Focardi, E.; Forti, F.; Giassi, A.; Giorgi, M. A.; Gregorio, A.; Ligabue, F.; Mannelli, E. B.; Marrocchesi, P. S.; Messineo, A.; Palla, F.; Rizzo, G.; Sanguinetti, G.; Spagnolo, P.; Steinberger, J.; Tenchini, R.; Tonelli, G.; Triggiani, G.; Vannini, C.; Venturi, A.; Verdini, P. G.; Walsh, J.; Betteridge, A. P.; Carter, J. M.; Green, M. G.; March, P. V.; Mir, Ll. M.; Medcalf, T.; Quazi, I. S.; Strong, J. A.; West, L. R.; Botterill, D. R.; Clifft, R. W.; Edgecock, T. R.; Edwards, M.; Fisher, S. M.; Jones, T. J.; Norton, P. R.; Salmon, D. P.; Thompson, J. C.; Bloch-Devaux, B.; Colas, P.; Duarte, H.; Kozanecki, W.; Lançon, E.; Lemaire, M. C.; Locci, E.; Perez, P.; Perrier, F.; Rander, J.; Renardy, J.-F.; Rosowsky, A.; Roussarie, A.; Schuller, J.-P.; Schwindling, J.; Si Mohand, D.; Vallage, B.; Johnson, R. P.; Litke, A. M.; Taylor, G.; Wear, J.; Ashman, J. G.; Babbage, W.; Booth, C. N.; Buttar, C.; Carney, R. E.; Cartwright, S.; Combley, F.; Hatfield, F.; Thompson, L. F.; Barberio, E.; Böhrer, A.; Brandt, S.; Cowan, G.; Grupen, C.; Lutters, G.; Rivera, F.; Schäfer, U.; Smolik, L.; Della Marina, R.; Giannini, G.; Gobbo, B.; Ragusa, F.; Bellantoni, L.; Chen, W.; Cinabro, D.; Conway, J. S.; Cowen, D. F.; Feng, Z.; Ferguson, D. P. S.; Gao, Y. S.; Grahl, J.; Harton, J. L.; Jared, R. C.; Leclaire, B. W.; Lishka, C.; Pan, Y. B.; Pater, J. R.; Saadi, Y.; Sharma, V.; Schmitt, M.; Shi, Z. H.; Walsh, A. M.; Weber, F. V.; Lan Wu, Sau; Wu, X.; Zheng, M.; Zobernig, G.; Aleph Collaboration
1993-06-01
The strong coupling constant is determined from the leptonic branching ratios, the lifetime, and the invariant mass distribution of the hadronic final state of the τ lepton, using data accumulated at LEP with the ALEPH detector. The strong coupling constant measurement, αs( mτ2) = 0.330±0.046, evolved to the Z mass yields αs( MZ2) = 0.188±0.005. The error includes experimental and theoretical uncertainties, the latter evaluated in the framework of the Shifman, Vainshtein and Zakharov (SVZ) approach. The method allows the non-perturbative contribution to the hadronic decay rate to be determined to be 0.3±0.5%.
Jet quenching parameters in strongly coupled nonconformal gauge theories
International Nuclear Information System (INIS)
Buchel, Alex
2006-01-01
Recently Liu, Rajagopal, and Wiedemann (LRW) [H. Liu, K. Rajagopal, and U. A. Wiedemann, hep-ph/0605178.] proposed a first principle, nonperturbative quantum field theoretic definition of 'jet quenching parameter' q-circumflex used in models of medium-induced radiative parton energy loss in nucleus-nucleus collisions at RHIC. Relating q-circumflex to a short-distance behavior of a certain lightlike Wilson loop, they used gauge theory-string theory correspondence to evaluate q-circumflex for the strongly coupled N=4 SU(N c ) gauge theory plasma. We generalize analysis of LRW to strongly coupled nonconformal gauge theory plasma. We find that a jet quenching parameter is gauge theory specific (not universal). Furthermore, it appears its value increases as the number of effective adjoint degrees of freedom of a gauge theory plasma increases
Equation of state of strongly coupled plasma mixtures
International Nuclear Information System (INIS)
DeWitt, H.E.
1984-01-01
Thermodynamic properties of strongly coupled (high density) plasmas of mixtures of light elements have been obtained by Monte Carlo simulations. For an assumed uniform charge background the equation of state of ionic mixtures is a simple extension of the one-component plasma EOS. More realistic electron screening effects are treated in linear response theory and with an appropriate electron dielectric function. Results have been obtained for the ionic pair distribution functions, and for the electric microfield distribution
Conductivity of strongly pumped superconductors. An electron-phonon system far from equilibrium
Energy Technology Data Exchange (ETDEWEB)
Krull, Holger
2015-01-29
The study of nonequilibrium physics is of great interest, because one can capture novel phenomena and properties which are hidden at equilibrium, e.g., one can study relaxation processes. A common way to study the nonequilibrium dynamics of a sample is a pump-probe experiment. In a pump probe experiment an intense laser pulse, the so called pump pulse, excites the sample and takes it out of equilibrium. After a certain delay time a second pulse, the probe pulse, measures the actual state of the sample. In this thesis, we theoretically study the pump-probe response of superconductors. On the one hand we are interest in the effect of a pump pulse and on the other hand we want to provide the pump-probe response, such that experimental measurement can be easily interpreted. In order to do this, we use the density matrix formalism to compute the pump-probe response of the system. In the density matrix formalism equations of motion are set up for expectation values of interest. In order to study the dynamics induced by a pump pulse, we compute the temporal evolution of the quasiparticle densities and the mean phonon amplitude. We find that the induced dynamics of the system depends on characteristics of the pump pulse. For short pulses, the system is pushed into the nonadiabatic regime. In this regime, the order parameter is lowered during the pump pulse and shows a 1/(√(t))-decaying oscillation afterwards. In addition, coherent phonons are generated, which is resonantly enhanced if the frequency of the order parameter oscillation is equal to the phonon frequency. For long pulses, the system is pushed into the adiabatic regime. In this regime, the order parameter is lowered during the pulse and remains almost constant afterwards. Further, there is almost no generation of coherent phonons. For the pump-probe response we compute the conductivity induced by the probe pulse. The conductivity is a typical observable in real pump-probe experiments. Hence, it is possible to compare the theoretical conductivity with a measured one. We find that the dynamics of the superconductor is reflected in oscillation of the conductivity as function of delay time between pump and probe pulse. This oscillation provides information of the frequency and decay time of the algebraically decaying order-parameter oscillations. Further, the dynamics of the coherent phonons is reflected by an oscillation of conductivity as function of delay time at the phonon frequency.
Conductivity of strongly pumped superconductors. An electron-phonon system far from equilibrium
International Nuclear Information System (INIS)
Krull, Holger
2015-01-01
The study of nonequilibrium physics is of great interest, because one can capture novel phenomena and properties which are hidden at equilibrium, e.g., one can study relaxation processes. A common way to study the nonequilibrium dynamics of a sample is a pump-probe experiment. In a pump probe experiment an intense laser pulse, the so called pump pulse, excites the sample and takes it out of equilibrium. After a certain delay time a second pulse, the probe pulse, measures the actual state of the sample. In this thesis, we theoretically study the pump-probe response of superconductors. On the one hand we are interest in the effect of a pump pulse and on the other hand we want to provide the pump-probe response, such that experimental measurement can be easily interpreted. In order to do this, we use the density matrix formalism to compute the pump-probe response of the system. In the density matrix formalism equations of motion are set up for expectation values of interest. In order to study the dynamics induced by a pump pulse, we compute the temporal evolution of the quasiparticle densities and the mean phonon amplitude. We find that the induced dynamics of the system depends on characteristics of the pump pulse. For short pulses, the system is pushed into the nonadiabatic regime. In this regime, the order parameter is lowered during the pump pulse and shows a 1/(√(t))-decaying oscillation afterwards. In addition, coherent phonons are generated, which is resonantly enhanced if the frequency of the order parameter oscillation is equal to the phonon frequency. For long pulses, the system is pushed into the adiabatic regime. In this regime, the order parameter is lowered during the pulse and remains almost constant afterwards. Further, there is almost no generation of coherent phonons. For the pump-probe response we compute the conductivity induced by the probe pulse. The conductivity is a typical observable in real pump-probe experiments. Hence, it is possible to compare the theoretical conductivity with a measured one. We find that the dynamics of the superconductor is reflected in oscillation of the conductivity as function of delay time between pump and probe pulse. This oscillation provides information of the frequency and decay time of the algebraically decaying order-parameter oscillations. Further, the dynamics of the coherent phonons is reflected by an oscillation of conductivity as function of delay time at the phonon frequency.
Correlated Fluctuations in Strongly Coupled Binary Networks Beyond Equilibrium
Directory of Open Access Journals (Sweden)
David Dahmen
2016-08-01
Full Text Available Randomly coupled Ising spins constitute the classical model of collective phenomena in disordered systems, with applications covering glassy magnetism and frustration, combinatorial optimization, protein folding, stock market dynamics, and social dynamics. The phase diagram of these systems is obtained in the thermodynamic limit by averaging over the quenched randomness of the couplings. However, many applications require the statistics of activity for a single realization of the possibly asymmetric couplings in finite-sized networks. Examples include reconstruction of couplings from the observed dynamics, representation of probability distributions for sampling-based inference, and learning in the central nervous system based on the dynamic and correlation-dependent modification of synaptic connections. The systematic cumulant expansion for kinetic binary (Ising threshold units with strong, random, and asymmetric couplings presented here goes beyond mean-field theory and is applicable outside thermodynamic equilibrium; a system of approximate nonlinear equations predicts average activities and pairwise covariances in quantitative agreement with full simulations down to hundreds of units. The linearized theory yields an expansion of the correlation and response functions in collective eigenmodes, leads to an efficient algorithm solving the inverse problem, and shows that correlations are invariant under scaling of the interaction strengths.
Strongly Coupled Models with a Higgs-like Boson*
Directory of Open Access Journals (Sweden)
Pich Antonio
2013-11-01
Full Text Available Considering the one-loop calculation of the oblique S and T parameters, we have presented a study of the viability of strongly-coupled scenarios of electroweak symmetry breaking with a light Higgs-like boson. The calculation has been done by using an effective Lagrangian, being short-distance constraints and dispersive relations the main ingredients of the estimation. Contrary to a widely spread believe, we have demonstrated that strongly coupled electroweak models with massive resonances are not in conflict with experimentalconstraints on these parameters and the recently observed Higgs-like resonance. So there is room for these models, but they are stringently constrained. The vector and axial-vector states should be heavy enough (with masses above the TeV scale, the mass splitting between them is highly preferred to be small and the Higgs-like scalar should have a WW coupling close to the Standard Model one. It is important to stress that these conclusions do not depend critically on the inclusion of the second Weinberg sum rule.
Strong Local-Nonlocal Coupling for Integrated Fracture Modeling
Energy Technology Data Exchange (ETDEWEB)
Littlewood, David John [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Silling, Stewart A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mitchell, John A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Seleson, Pablo D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bond, Stephen D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Parks, Michael L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Turner, Daniel Z. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Burnett, Damon J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ostien, Jakob [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Gunzburger, Max [Florida State Univ., Tallahassee, FL (United States)
2015-09-01
Peridynamics, a nonlocal extension of continuum mechanics, is unique in its ability to capture pervasive material failure. Its use in the majority of system-level analyses carried out at Sandia, however, is severely limited, due in large part to computational expense and the challenge posed by the imposition of nonlocal boundary conditions. Combined analyses in which peridynamics is em- ployed only in regions susceptible to material failure are therefore highly desirable, yet available coupling strategies have remained severely limited. This report is a summary of the Laboratory Directed Research and Development (LDRD) project "Strong Local-Nonlocal Coupling for Inte- grated Fracture Modeling," completed within the Computing and Information Sciences (CIS) In- vestment Area at Sandia National Laboratories. A number of challenges inherent to coupling local and nonlocal models are addressed. A primary result is the extension of peridynamics to facilitate a variable nonlocal length scale. This approach, termed the peridynamic partial stress, can greatly reduce the mathematical incompatibility between local and nonlocal equations through reduction of the peridynamic horizon in the vicinity of a model interface. A second result is the formulation of a blending-based coupling approach that may be applied either as the primary coupling strategy, or in combination with the peridynamic partial stress. This blending-based approach is distinct from general blending methods, such as the Arlequin approach, in that it is specific to the coupling of peridynamics and classical continuum mechanics. Facilitating the coupling of peridynamics and classical continuum mechanics has also required innovations aimed directly at peridynamic models. Specifically, the properties of peridynamic constitutive models near domain boundaries and shortcomings in available discretization strategies have been addressed. The results are a class of position-aware peridynamic constitutive laws for
Transport Theory for Plasmas that are Strongly Magnetized and Strongly Coupled
Baalrud, Scott; Daligault, Jerome
2016-10-01
Plasmas with components that are magnetized, strongly coupled, or both arise in a variety of frontier plasma physics experiments including magnetized dusty plasmas, nonneutral plasmas, magnetized ICF concepts, as well as from self-generated fields in ICF. Here, a species is considered strongly magnetized if the gyroradius is smaller than the spatial scale over which Coulomb interactions occur. A theory for transport properties is described that treats a wide range of both coupling and magnetization strengths. The approach is based on an extension of the recent effective potential transport theory to include a strong magnetic field. The underlying kinetic theory is based on an extension of the Boltzmann equation to include a strong magnetic field in the dynamics of binary scattering events. Corresponding magnetohydrodynamic equations are derived by solving the kinetic equation using a Chapman-Enskog like spectral method. Results are compared with classical molecular dynamics simulations of self-diffusion of the one component plasmas, and with simulations of parallel to perpendicular temperature equilibration of an initially anisotropic distribution. This material is based upon work supported by AFOSR Award FA9550-16-1-0221 and DOE OFES Award DE-SC0016159.
Enhancement of low-temperature thermometry by strong coupling
Correa, Luis A.; Perarnau-Llobet, Martí; Hovhannisyan, Karen V.; Hernández-Santana, Senaida; Mehboudi, Mohammad; Sanpera, Anna
2017-12-01
We consider the problem of estimating the temperature T of a very cold equilibrium sample. The temperature estimates are drawn from measurements performed on a quantum Brownian probe strongly coupled to it. We model this scenario by resorting to the canonical Caldeira-Leggett Hamiltonian and find analytically the exact stationary state of the probe for arbitrary coupling strength. In general, the probe does not reach thermal equilibrium with the sample, due to their nonperturbative interaction. We argue that this is advantageous for low-temperature thermometry, as we show in our model that (i) the thermometric precision at low T can be significantly enhanced by strengthening the probe-sampling coupling, (ii) the variance of a suitable quadrature of our Brownian thermometer can yield temperature estimates with nearly minimal statistical uncertainty, and (iii) the spectral density of the probe-sample coupling may be engineered to further improve thermometric performance. These observations may find applications in practical nanoscale thermometry at low temperatures—a regime which is particularly relevant to quantum technologies.
Strongly coupled dusty plasmas: crystals, liquids, clusters and waves
International Nuclear Information System (INIS)
Jeng-Mei Liu; Wen-Tau Juan; Ju-Wang Hsu; Zen-Hong Huang; Lin I
1999-01-01
The dusty plasma is a system that consists of many strongly-charged fine dust particles suspended in a plasma background. The slow dynamics and strong coupling due to the large mass and charges lead to the formation of highly-ordered dust crystal structures suspended in the plasma background, which can be directly observed. The dusty plasma forms a link to the area of condensed matter physics for the study of many interesting microscopic phenomena from order to disorder. In this paper, we introduce the special properties of this system from the viewpoint of conventional plasma physics, then we briefly review past works on the structure and dynamical behaviour from the highly-ordered state, through the melting and liquid states with associated vortex-type excitation and anomalous diffusion, to the state with self-organized macroscopic dust waves after losing microscopic order. The first observation of strongly-coupled dust Coulomb clusters with small numbers of particles from a few to a few hundred, which resemble classical atoms, is also demonstrated. (author)
Strongly Coupled Chameleons and the Neutronic Quantum Bouncer
International Nuclear Information System (INIS)
Brax, Philippe; Pignol, Guillaume
2011-01-01
We consider the potential detection of chameleons using bouncing ultracold neutrons. We show that the presence of a chameleon field over a planar plate would alter the energy levels of ultracold neutrons in the terrestrial gravitational field. When chameleons are strongly coupled to nuclear matter, β > or approx. 10 8 , we find that the shift in energy levels would be detectable with the forthcoming GRANIT experiment, where a sensitivity of the order of 1% of a peV is expected. We also find that an extremely large coupling β > or approx. 10 11 would lead to new bound states at a distance of order 2 μm, which is already ruled out by previous Grenoble experiments. The resulting bound, β 11 , is already 3 orders of magnitude better than the upper bound, β 14 , from precision tests of atomic spectra.
Strong coupling QCD at finite baryon-number density
International Nuclear Information System (INIS)
Karsch, F.; Muetter, K.H.
1989-01-01
We present a new representation of the partition function for strong-coupling QCD which is suitable also for finite baryon-number-density simulations. This enables us to study the phase structure in the canonical formulation (with fixed baryon number B) as well as the grand canonical one (with fixed chemical potential μ). We find a clear signal for a first-order chiral phase transition at μ c a=0.63. The critical baryon-number density n c a 3 =0.045 is only slightly higher than the density of nuclear matter. (orig.)
Topological Zak phase in strongly coupled LC circuits
Goren, Tal; Plekhanov, Kirill; Appas, Félicien; Le Hur, Karyn
2018-01-01
We show the emergence of topological Bogoliubov bosonic excitations in the relatively strong coupling limit of an LC (inductance-capacitance) one-dimensional quantum circuit. This dimerized chain model reveals a Z2 local symmetry as a result of the counter-rotating wave (pairing) terms. The topology is protected by the sublattice symmetry, represented by an antiunitary transformation. We present a method to measure the winding of the topological Zak phase across the Brillouin zone by a reflection measurement of (microwave) light. Our method probes bulk quantities and can be implemented even in small systems. We study the robustness of edge modes toward disorder.
Black hole thermodynamics from calculations in strongly coupled gauge theory.
Kabat, D; Lifschytz, G; Lowe, D A
2001-02-19
We develop an approximation scheme for the quantum mechanics of N D0-branes at finite temperature in the 't Hooft large- N limit. The entropy of the quantum mechanics calculated using this approximation agrees well with the Bekenstein-Hawking entropy of a ten-dimensional nonextremal black hole with 0-brane charge. This result is in accordance with the duality conjectured by Itzhaki, Maldacena, Sonnenschein, and Yankielowicz [Phys. Rev. D 58, 046004 (1998)]. Our approximation scheme provides a model for the density matrix which describes a black hole in the strongly coupled quantum mechanics.
Strongly coupled stimulated Brillouin amplification in pump-ionizing plasma
Peng, H.; Wu, Z. H.; Zuo, Y. L.; Zhou, K. N.; Wang, X. D.; Li, Q.; Zhu, H. Y.; Su, J. Q.
2018-02-01
Laser amplification based on strongly coupled stimulated Brillouin scattering in plasma is investigated. The pump and seed are at the same wavelength of 800 nm and the same duration of 3.5 ps, but with a different intensity. The plasma is produced by the front part of the pump via tunnel ionization from hydrogen. The hydrogen is fully ionized to eliminate small-scale density fluctuations in the plasma, so the transmission level of the seed is enhanced to 22%, and a relative amplification factor of 6 is obtained.
Strong-coupling approach to nematicity in the cuprates
Orth, Peter Philipp; Jeevanesan, Bhilahari; Schmalian, Joerg; Fernandes, Rafael
The underdoped cuprate superconductor YBa2Cu3O7-δ is known to exhibit an electronic nematic phase in proximity to antiferromagnetism. While nematicity sets in at large temperatures of T ~ 150 K, static spin density wave order only emerges at much lower temperatures. The magnetic response shows a strong in-plane anisotropy, displaying incommensurate Bragg peaks along one of the crystalline directions and a commensurate peak along the other one. Such an anisotropy persists even in the absence of long-range magnetic order at higher temperatures, marking the onset of nematic order. Here we theoretically investigate this situation using a strong-coupling method that takes into account both the localized Cu spins and the holes doped into the oxygen orbitals. We derive an effective spin Hamiltonian and show that charge fluctuations promote an enhancement of the nematic susceptibility near the antiferromagnetic transition temperature.
Double perovskites with strong spin-orbit coupling
Cook, Ashley M.
We first present theoretical analysis of powder inelastic neutron scattering experiments in Ba2FeReO6 performed by our experimental collaborators. Ba2FeReO6, a member of the double perovskite family of materials, exhibits half-metallic behavior and high Curie temperatures Tc, making it of interest for spintronics applications. To interpret the experimental data, we develop a local moment model, which incorporates the interaction of Fe spins with spin-orbital locked magnetic moments on Re, and show that it captures the experimental observations. We then develop a tight-binding model of the double perovskite Ba 2FeReO6, a room temperature ferrimagnet with correlated and spin-orbit coupled Re t2g electrons moving in the background of Fe moments stabilized by Hund's coupling. We show that for such 3d/5d double perovskites, strong correlations on the 5d-element (Re) are essential in driving a half-metallic ground state. Incorporating both strong spin-orbit coupling and the Hubbard repulsion on Re leads to a band structure consistent with ab initio calculations. The uncovered interplay of strong correlations and spin-orbit coupling lends partial support to our previous work, which used a local moment description to capture the spin wave dispersion found in neutron scattering measurements. We then adapt this tight-binding model to study {111}-grown bilayers of half-metallic double perovskites such as Sr2FeMoO6. The combination of spin-orbit coupling, inter-orbital hybridization and symmetry-allowed trigonal distortion leads to a rich phase diagram with tunable ferromagnetic order, topological C= +/-1, +/-2 Chern bands, and a C = +/-2 quantum anomalous Hall insulator regime. We have also performed theoretical analysis of inelastic neutron scattering (INS) experiments to investigate the magnetic excitations in the weakly distorted face-centered-cubic (fcc) iridate double perovskites La2ZnIrO 6 and La2MgIrO6. Models with dominant Kitaev exchange seem to most naturally
Hinsche, Nicki Frank; Sommer Thygesen, Kristian
2018-01-01
Transition metal dichalcogenides have recently emerged as promising two-dimensional materials with intriguing electronic properties. Existing calculations of intrinsic phonon-limited electronic transport so far have concentrated on the semicondcucting members of this family. In this paper we extend these studies by investigating the influence of electron-phonon coupling on the electronic transport properties and band renormalization of prototype inherent metallic bulk and monolayer TaS2. Based on density functional perturbation theory and semi-classical Boltzmann transport calculations, promising room temperature mobilities and sheet conductances are found, which can compete with other established 2D materials, leaving TaS2 as promising material candidate for transparent conductors or as atomically thin interconnects. Throughout the paper, the electronic and transport properties of TaS2 are compared to those of its isoelectronic counterpart TaSe2 and additional informations to the latter are given. We furthermore comment on the conventional superconductivity in TaS2, where no phonon-mediated enhancement of T C in the monolayer compared to the bulk state was found.
Features of electron-phonon interactions in nanotubes with chiral symmetry in magnetic field
Kibis, O V
2001-01-01
Interaction of the electrons with acoustic phonons in the nanotube with chiral symmetry by availability of the magnetic field, parallel to the nanotube axis, is considered. It is shown that the electron energy spectrum is asymmetric relative to the electron wave vector inversion and for that reason the electron-phonon interaction appears to be different for similar phonons with mutually contrary directions of the wave vector. This phenomenon leads to origination of the electromotive force by the spatially uniform electron gas heating and to appearance of the quadrupole component in the nanotube volt-ampere characteristics
Electromagnetic microwaves in metal films with electron-phonon interaction and a dc magnetic field
DEFF Research Database (Denmark)
Hasselberg, L.E.
1976-01-01
A quantum-mechanical treatment of electromagnetic microwaves is performed for a metal film. The directions of the exterior ac and dc fields are taken to be arbitrary and boundary conditions for the electrons are assumed to be specular. The relation between the current and the electromagnetic field...... in the transmission spectrum can perhaps be obtained by assuming a finite Debye temperature and specular reflections of the electrons at the boundary surfaces. A sharp peak entirely caused by the finite electron-phonon interaction is also discussed....
Electron-phonon scattering from Green’s function transport combined with molecular dynamics
DEFF Research Database (Denmark)
Markussen, Troels; Palsgaard, Mattias Lau Nøhr; Stradi, Daniele
2017-01-01
approach by comparing to mobilities and conductivities obtained by the Boltzmann transport equation for different bulk and one-dimensional systems. For bulk silicon and gold we compare against experimental values. We discuss limitations and advantages of each of the computational approaches.......We present a conceptually simple method for treating electron-phonon scattering and phonon limited mobilities. By combining Green’s function based transport calculations and molecular dynamics, we obtain a temperature dependent transmission from which we evaluate the mobility. We validate our...
Strong wave/mean-flow coupling in baroclinic acoustic streaming
Chini, Greg; Michel, Guillaume
2017-11-01
Recently, Chini et al. demonstrated the potential for large-amplitude acoustic streaming in compressible channel flows subjected to strong background cross-channel density variations. In contrast with classic Rayleigh streaming, standing acoustic waves of O (ɛ) amplitude acquire vorticity owing to baroclinic torques acting throughout the domain rather than via viscous torques acting in Stokes boundary layers. More significantly, these baroclinically-driven streaming flows have a magnitude that also is O (ɛ) , i.e. comparable to that of the sound waves. In the present study, the consequent potential for fully two-way coupling between the waves and streaming flows is investigated using a novel WKBJ analysis. The analysis confirms that the wave-driven streaming flows are sufficiently strong to modify the background density gradient, thereby modifying the leading-order acoustic wave structure. Simulations of the wave/mean-flow system enabled by the WKBJ analysis are performed to illustrate the nature of the two-way coupling, which contrasts sharply with classic Rayleigh streaming, for which the waves can first be determined and the streaming flows subsequently computed.
Strongly Coupled Magnetic and Electronic Transitions in Multivalent Strontium Cobaltites.
Lee, J H; Choi, Woo Seok; Jeen, H; Lee, H-J; Seo, J H; Nam, J; Yeom, M S; Lee, H N
2017-11-22
The topotactic phase transition in SrCoO x (x = 2.5-3.0) makes it possible to reversibly transit between the two distinct phases, i.e. the brownmillerite SrCoO 2.5 that is a room-temperature antiferromagnetic insulator (AFM-I) and the perovskite SrCoO 3 that is a ferromagnetic metal (FM-M), owing to their multiple valence states. For the intermediate x values, the two distinct phases are expected to strongly compete with each other. With oxidation of SrCoO 2.5 , however, it has been conjectured that the magnetic transition is decoupled to the electronic phase transition, i.e., the AFM-to-FM transition occurs before the insulator-to-metal transition (IMT), which is still controversial. Here, we bridge the gap between the two-phase transitions by density-functional theory calculations combined with optical spectroscopy. We confirm that the IMT actually occurs concomitantly with the FM transition near the oxygen content x = 2.75. Strong charge-spin coupling drives the concurrent IMT and AFM-to-FM transition, which fosters the near room-T magnetic transition characteristic. Ultimately, our study demonstrates that SrCoO x is an intriguingly rare candidate for inducing coupled magnetic and electronic transition via fast and reversible redox reactions.
Equilibrium statistical mechanics of strongly coupled plasmas by numerical simulation
International Nuclear Information System (INIS)
DeWitt, H.E.
1977-01-01
Numerical experiments using the Monte Carlo method have led to systematic and accurate results for the thermodynamic properties of strongly coupled one-component plasmas and mixtures of two nuclear components. These talks are intended to summarize the results of Monte Carlo simulations from Paris and from Livermore. Simple analytic expressions for the equation of state and other thermodynamic functions have been obtained in which there is a clear distinction between a lattice-like static portion and a thermal portion. The thermal energy for the one-component plasma has a simple power dependence on temperature, (kT)/sup 3 / 4 /, that is identical to Monte Carlo results obtained for strongly coupled fluids governed by repulsive l/r/sup n/ potentials. For two-component plasmas the ion-sphere model is shown to accurately represent the static portion of the energy. Electron screening is included in the Monte Carlo simulations using linear response theory and the Lindhard dielectric function. Free energy expressions have been constructed for one and two component plasmas that allow easy computation of all thermodynamic functions
Pair correlation functions of strongly coupled two-temperature plasma
Shaffer, Nathaniel R.; Tiwari, Sanat Kumar; Baalrud, Scott D.
2017-09-01
Using molecular dynamics simulations, we perform the first direct tests of three proposed models for the pair correlation functions of strongly coupled plasmas with species of unequal temperature. The models are all extensions of the Ornstein-Zernike/hypernetted-chain theory used to good success for equilibrium plasmas. Each theory is evaluated at several coupling strengths, temperature ratios, and mass ratios for a model plasma in which the electrons are positively charged. We show that the model proposed by Seuferling et al. [Phys. Rev. A 40, 323 (1989)] agrees well with molecular dynamics over a wide range of mass and temperature ratios, as well as over a range of coupling strength similar to that of the equilibrium hypernetted-chain (HNC) theory. The SVT model also correctly predicts the strength of interspecies correlations and exhibits physically reasonable long-wavelength limits of the static structure factors. Comparisons of the SVT model with the Yukawa one-component plasma (YOCP) model are used to show that ion-ion pair correlations are well described by the YOCP model up to Γe≈1 , beyond which it rapidly breaks down.
Strongly coupled inorganic/nanocarbon hybrid materials for advanced electrocatalysis.
Liang, Yongye; Li, Yanguang; Wang, Hailiang; Dai, Hongjie
2013-02-13
Electrochemical systems, such as fuel cell and water splitting devices, represent some of the most efficient and environmentally friendly technologies for energy conversion and storage. Electrocatalysts play key roles in the chemical processes but often limit the performance of the entire systems due to insufficient activity, lifetime, or high cost. It has been a long-standing challenge to develop efficient and durable electrocatalysts at low cost. In this Perspective, we present our recent efforts in developing strongly coupled inorganic/nanocarbon hybrid materials to improve the electrocatalytic activities and stability of inorganic metal oxides, hydroxides, sulfides, and metal-nitrogen complexes. The hybrid materials are synthesized by direct nucleation, growth, and anchoring of inorganic nanomaterials on the functional groups of oxidized nanocarbon substrates including graphene and carbon nanotubes. This approach affords strong chemical attachment and electrical coupling between the electrocatalytic nanoparticles and nanocarbon, leading to nonprecious metal-based electrocatalysts with improved activity and durability for the oxygen reduction reaction for fuel cells and chlor-alkali catalysis, oxygen evolution reaction, and hydrogen evolution reaction. X-ray absorption near-edge structure and scanning transmission electron microscopy are employed to characterize the hybrids materials and reveal the coupling effects between inorganic nanomaterials and nanocarbon substrates. Z-contrast imaging and electron energy loss spectroscopy at single atom level are performed to investigate the nature of catalytic sites on ultrathin graphene sheets. Nanocarbon-based hybrid materials may present new opportunities for the development of electrocatalysts meeting the requirements of activity, durability, and cost for large-scale electrochemical applications.
The strong coupling constant of QCD with four flavors
Energy Technology Data Exchange (ETDEWEB)
Tekin, Fatih
2010-11-01
In this thesis we study the theory of strong interaction Quantum Chromodynamics on a space-time lattice (lattice QCD) with four flavors of dynamical fermions by numerical simulations. In the early days of lattice QCD, only pure gauge field simulations were accessible to the computational facilities and the effects of quark polarization were neglected. The so-called fermion determinant in the path integral was set to one (quenched approximation). The reason for this approximation was mainly the limitation of computational power because the inclusion of the fermion determinant required an enormous numerical effort. However, for full QCD simulations the virtual quark loops had to be taken into account and the development of new machines and new algorithmic techniques made the so-called dynamical simulations with at least two flavors possible. In recent years, different collaborations studied lattice QCD with dynamical fermions. In our project we study lattice QCD with four degenerated flavors of O(a) improved Wilson quarks in the Schroedinger functional scheme and calculate the energy dependence of the strong coupling constant. For this purpose, we determine the O(a) improvement coefficient c{sub sw} with four flavors and use this result to calculate the step scaling function of QCD with four flavors which describes the scale evolution of the running coupling. Using a recursive finite-size technique, the {lambda} parameter is determined in units of a technical scale L{sub max} which is an unambiguously defined length in the hadronic regime. The coupling {alpha}{sub SF} of QCD in the so-called Schroedinger functional scheme is calculated over a wide range of energies non-perturbatively and compared with 2-loop and 3-loop perturbation theory as well as with the non-perturbative result for only two flavors. (orig.)
Perspective: Coulomb fluids--weak coupling, strong coupling, in between and beyond.
Naji, Ali; Kanduc, Matej; Forsman, Jan; Podgornik, Rudolf
2013-10-21
We present a personal view on the current state of statistical mechanics of Coulomb fluids with special emphasis on the interactions between macromolecular surfaces, concentrating on the weak and the strong coupling limits. Both are introduced for a (primitive) counterion-only system in the presence of macroscopic, uniformly charged boundaries, where they can be derived systematically. Later we show how this formalism can be generalized to the cases with additional characteristic length scales that introduce new coupling parameters into the problem. These cases most notably include asymmetric ionic mixtures with mono- and multivalent ions that couple differently to charged surfaces, ions with internal charge (multipolar) structure and finite static polarizability, where weak and strong coupling limits can be constructed by analogy with the counterion-only case and lead to important new insights into their properties that cannot be derived by any other means.
Mathematical structure of Rabi oscillations in the strong coupling regime
International Nuclear Information System (INIS)
Fujii, Kazuyuki
2003-01-01
In this paper, we generalize the Jaynes-Cummings Hamiltonian by making use of some operators based on Lie algebras su(1, 1) and su(2), and study a mathematical structure of Rabi floppings of these models in the strong coupling regime. We show that Rabi frequencies are given by matrix elements of generalized coherent operators (Fujii K 2002 Preprint quant-ph/0202081) under the rotating-wave approximation. In the first half, we make a general review of coherent operators and generalized coherent ones based on Lie algebras su(1, 1) and su(2). In the latter half, we carry out a detailed examination of Frasca (Frasca M 2001 Preprint quant-ph/0111134) and generalize his method, and moreover present some related problems. We also apply our results to the construction of controlled unitary gates in quantum computation. Lastly, we make a brief comment on application to holonomic quantum computation
Charge pumping in strongly coupled molecular quantum dots
Haughian, Patrick; Yap, Han Hoe; Gong, Jiangbin; Schmidt, Thomas L.
2017-11-01
The interaction between electrons and the vibrational degrees of freedom of a molecular quantum dot can lead to an exponential suppression of the conductance, an effect which is commonly termed Franck-Condon blockade. Here, we investigate this effect in a quantum dot driven by time-periodic gate voltages and tunneling amplitudes using nonequilibrium Green's functions and a Floquet expansion. Building on previous results showing that driving can lift the Franck-Condon blockade, we investigate driving protocols which can be used to pump charge across the quantum dot. In particular, we show that due to the strongly coupled nature of the system, the pump current at resonance is an exponential function of the drive strength.
On the flavor problem in strongly coupled theories
Energy Technology Data Exchange (ETDEWEB)
Bauer, Martin
2012-11-28
This thesis is on the flavor problem of Randall Sundrum models and their strongly coupled dual theories. These models are particularly well motivated extensions of the Standard Model, because they simultaneously address the gauge hierarchy problem and the hierarchies in the quark masses and mixings. In order to put this into context, special attention is given to concepts underlying the theories which can explain the hierarchy problem and the flavor structure of the Standard Model (SM). The AdS/CFT duality is introduced and its implications for the Randall Sundrum model with fermions in the bulk and general bulk gauge groups is investigated. It is shown that the different terms in the general 5D propagator of a bulk gauge field can be related to the corresponding diagrams of the strongly coupled dual, which allows for a deeper understanding of the origin of flavor changing neutral currents generated by the exchange of the Kaluza Klein excitations of these bulk fields. In the numerical analysis, different observables which are sensitive to corrections from the tree-level exchange of these resonances will be presented on the basis of updated experimental data from the Tevatron and LHC experiments. This includes electroweak precision observables, namely corrections to the S and T parameters followed by corrections to the Zb anti b vertex, flavor changing observables with flavor changes at one vertex, viz. B(B{sub d}{yields}{mu}{sup +}{mu}{sup -}) and B(B{sub s}{yields}{mu}{sup +}{mu}{sup -}), and two vertices, viz. S{sub {psi}{phi}} and vertical stroke {epsilon}{sub K} vertical stroke, as well as bounds from direct detection experiments. The analysis will show that all of these bounds can be brought in agreement with a new physics scale {Lambda}{sub NP} in the TeV range, except for the CP violating quantity vertical stroke {epsilon}{sub K} vertical stroke, which requires {Lambda}{sub NP}=O(10) TeV in the absence of fine-tuning. The numerous modifications of the
Quantum Thermodynamics in Strong Coupling: Heat Transport and Refrigeration
Directory of Open Access Journals (Sweden)
Gil Katz
2016-05-01
Full Text Available The performance characteristics of a heat rectifier and a heat pump are studied in a non-Markovian framework. The device is constructed from a molecule connected to a hot and cold reservoir. The heat baths are modelled using the stochastic surrogate Hamiltonian method. The molecule is modelled by an asymmetric double-well potential. Each well is semi-locally connected to a heat bath composed of spins. The dynamics are driven by a combined system–bath Hamiltonian. The temperature of the baths is regulated by a secondary spin bath composed of identical spins in thermal equilibrium. A random swap operation exchange spins between the primary and secondary baths. The combined system is studied in various system–bath coupling strengths. In all cases, the average heat current always flows from the hot towards the cold bath in accordance with the second law of thermodynamics. The asymmetry of the double well generates a rectifying effect, meaning that when the left and right baths are exchanged the heat current follows the hot-to-cold direction. The heat current is larger when the high frequency is coupled to the hot bath. Adding an external driving field can reverse the transport direction. Such a refrigeration effect is modelled by a periodic driving field in resonance with the frequency difference of the two potential wells. A minimal driving amplitude is required to overcome the heat leak effect. In the strong driving regime the cooling power is non-monotonic with the system–bath coupling.
Peptide-microgel interactions in the strong coupling regime.
Hansson, Per; Bysell, Helena; Månsson, Ronja; Malmsten, Martin
2012-09-06
The interaction between lightly cross-linked poly(acrylic acid) microgels and oppositely charged peptides was investigated as a function of peptide length, charge density, pH, and salt concentration, with emphasis on the strong coupling regime at high charge contrast. By micromanipulator-assisted light microscopy, the equilibrium volume response of single microgel particles upon oligolysine and oligo(lysine/alanine) absorption could be monitored in a controlled fashion. Results show that microgel deswelling, caused by peptide binding and network neutralization, increases with peptide length (3 attraction between the network chains is described using an exponential force law, and the network elasticity by the inverse Langevin theory. The model was used to calculate the composition of microgels in contact with reservoir solutions of peptides and simple electrolytes. At high electrostatic coupling, the calculated swelling curves were found to display first-order phase transition behavior. The model was demonstrated to capture pH- and electrolyte-dependent microgel swelling, as well as effects of peptide length and charge density on microgel deswelling. The analysis demonstrated that the peptide charge (length), rather than the peptide charge density, determines microgel deswelling. Furthermore, a transition between continuous and discrete network collapse was identified, consistent with experimental results in the present investigations, as well as with results from the literature on microgel deswelling caused by multivalent cations.
Thermalization and confinement in strongly coupled gauge theories
Directory of Open Access Journals (Sweden)
Ishii Takaaki
2016-01-01
Full Text Available Quantum field theories of strongly interacting matter sometimes have a useful holographic description in terms of the variables of a gravitational theory in higher dimensions. This duality maps time dependent physics in the gauge theory to time dependent solutions of the Einstein equations in the gravity theory. In order to better understand the process by which “real world” theories such as QCD behave out of thermodynamic equilibrium, we study time dependent perturbations to states in a model of a confining, strongly coupled gauge theory via holography. Operationally, this involves solving a set of non-linear Einstein equations supplemented with specific time dependent boundary conditions. The resulting solutions allow one to comment on the timescale by which the perturbed states thermalize, as well as to quantify the properties of the final state as a function of the perturbation parameters. We comment on the influence of the dual gauge theory’s confinement scale on these results, as well as the appearance of a previously anticipated universal scaling regime in the “abrupt quench” limit.
Holographic Floquet states I: a strongly coupled Weyl semimetal
Hashimoto, Koji; Kinoshita, Shunichiro; Murata, Keiju; Oka, Takashi
2017-05-01
Floquet states can be realized in quantum systems driven by continuous time-periodic perturbations. It is known that a state known as the Floquet Weyl semimetal can be realized when free Dirac fermions are placed in a rotating electric field. What will happen if strong interaction is introduced to this system? Will the interaction wash out the characteristic features of Weyl semimetals such as the Hall response? Is there a steady state and what is its thermodynamic behavior? We answer these questions using AdS/CFT correspondence in the N = 2 supersymmetric massless QCD in a rotating electric field in the large N c limit realizing the first example of a "holographic Floquet state". In this limit, gluons not only mediate interaction, but also act as an energy reservoir and stabilize the nonequilibrium steady state (NESS). We obtain the electric current induced by a rotating electric field: in the high frequency region, the Ohm's law is satisfied, while we recover the DC nonlinear conductivity at low frequency, which was obtained holographically in a previous work. The thermodynamic properties of the NESS, e.g., fluctuation-dissipation relation, is characterized by the effective Hawking temperature that is defined from the effective horizon giving a holographic meaning to the "periodic thermodynamic" concept. In addition to the strong (pump) rotating electric field, we apply an additional weak (probe) electric field in the spirit of the pump-probe experiments done in condensed matter experiments. Weak DC and AC probe analysis in the background rotating electric field shows Hall currents as a linear response, therefore the Hall response of Floquet Weyl semimetals survives at the strong coupling limit. We also find frequency mixed response currents, i.e., a heterodyning effect, characteristic to periodically driven Floquet systems.
Large mass hierarchies from strongly-coupled dynamics
Athenodorou, Andreas; Bennett, Ed; Bergner, Georg; Elander, Daniel; Lin, C.-J. David; Lucini, Biagio; Piai, Maurizio
2016-06-01
Besides the Higgs particle discovered in 2012, with mass 125 GeV, recent LHC data show tentative signals for new resonances in diboson as well as diphoton searches at high center-of-mass energies (2 TeV and 750 GeV, respectively). If these signals are confirmed (or other new resonances are discovered at the TeV scale), the large hierarchies between masses of new bosons require a dynamical explanation. Motivated by these tentative signals of new physics, we investigate the theoretical possibility that large hierarchies in the masses of glueballs could arise dynamically in new strongly-coupled gauge theories extending the standard model of particle physics. We study lattice data on non-Abelian gauge theories in the (near-)conformal regime as well as a simple toy model in the context of gauge/gravity dualities. We focus our attention on the ratio R between the mass of the lightest spin-2 and spin-0 resonances, that for technical reasons is a particularly convenient and clean observable to study. For models in which (non-perturbative) large anomalous dimensions arise dynamically, we show indications that this mass ratio can be large, with R>5. Moreover,our results suggest that R might be related to universal properties of the IR fixed point. Our findings provide an interesting step towards understanding large mass ratios in the non-perturbative regime of quantum field theories with (near) IR conformal behaviour.
Stochastic and Macroscopic Thermodynamics of Strongly Coupled Systems
Directory of Open Access Journals (Sweden)
Christopher Jarzynski
2017-01-01
Full Text Available We develop a thermodynamic framework that describes a classical system of interest S that is strongly coupled to its thermal environment E. Within this framework, seven key thermodynamic quantities—internal energy, entropy, volume, enthalpy, Gibbs free energy, heat, and work—are defined microscopically. These quantities obey thermodynamic relations including both the first and second law, and they satisfy nonequilibrium fluctuation theorems. We additionally impose a macroscopic consistency condition: When S is large, the quantities defined within our framework scale up to their macroscopic counterparts. By satisfying this condition, we demonstrate that a unifying framework can be developed, which encompasses both stochastic thermodynamics at one end, and macroscopic thermodynamics at the other. A central element in our approach is a thermodynamic definition of the volume of the system of interest, which converges to the usual geometric definition when S is large. We also sketch an alternative framework that satisfies the same consistency conditions. The dynamics of the system and environment are modeled using Hamilton’s equations in the full phase space.
Effect of random charge fluctuation on strongly coupled dusty Plasma
Issaad, M.; Rouiguia, L.; Djebli, M.
2008-09-01
Modeling the interaction between particles is an open issue in dusty plasma. We dealt with strongly coupled dust particles in two dimensional confined system. For small number of clusters, we investigate the effect of random charge fluctuation on background configuration. The study is conducted for a short rang as well as a long rang potential interaction. Numerical simulation is performed using Monte-Carlo simulation in the presence of parabolic confinement and at low temperature. We have studied the background configurations for a dust particles with constant charge and in the presence of random charge fluctuation due to the discrete nature of charge carriers. The latter is studied for a positively charged dust when the dominant charging process is due to photo-emission from the dust surface. It is found, for small classical cluster consisting of small number of particles, short rang potential gives the same result as long rang one. It is also found that the random charge fluctuation affect the background configurations.
Weak-coupling superconductivity in a strongly correlated iron pnictide.
Charnukha, A; Post, K W; Thirupathaiah, S; Pröpper, D; Wurmehl, S; Roslova, M; Morozov, I; Büchner, B; Yaresko, A N; Boris, A V; Borisenko, S V; Basov, D N
2016-01-05
Iron-based superconductors have been found to exhibit an intimate interplay of orbital, spin, and lattice degrees of freedom, dramatically affecting their low-energy electronic properties, including superconductivity. Albeit the precise pairing mechanism remains unidentified, several candidate interactions have been suggested to mediate the superconducting pairing, both in the orbital and in the spin channel. Here, we employ optical spectroscopy (OS), angle-resolved photoemission spectroscopy (ARPES), ab initio band-structure, and Eliashberg calculations to show that nearly optimally doped NaFe0.978Co0.022As exhibits some of the strongest orbitally selective electronic correlations in the family of iron pnictides. Unexpectedly, we find that the mass enhancement of itinerant charge carriers in the strongly correlated band is dramatically reduced near the Γ point and attribute this effect to orbital mixing induced by pronounced spin-orbit coupling. Embracing the true band structure allows us to describe all low-energy electronic properties obtained in our experiments with remarkable consistency and demonstrate that superconductivity in this material is rather weak and mediated by spin fluctuations.
Strongly coupled gauge theories: What can lattice calculations teach us?
Hasenfratz, A.; Brower, R. C.; Rebbi, C.; Weinberg, E.; Witzel, O.
2017-12-01
The dynamical origin of electroweak symmetry breaking is an open question with many possible theoretical explanations. Strongly coupled systems predicting the Higgs boson as a bound state of a new gauge-fermion interaction form one class of candidate models. Due to increased statistics, LHC run II will further constrain the phenomenologically viable models in the near future. In the meanwhile it is important to understand the general properties and specific features of the different competing models. In this work we discuss many-flavor gauge-fermion systems that contain both massless (light) and massive fermions. The former provide Goldstone bosons and trigger electroweak symmetry breaking, while the latter indirectly influence the infrared dynamics. Numerical results reveal that such systems can exhibit a light 0++ isosinglet scalar, well separated from the rest of the spectrum. Further, when we set the scale via the vev of electroweak symmetry breaking, we predict a 2 TeV vector resonance which could be a generic feature of SU(3) gauge theories.
Ising models of strongly coupled biological networks with multivariate interactions
Merchan, Lina; Nemenman, Ilya
2013-03-01
Biological networks consist of a large number of variables that can be coupled by complex multivariate interactions. However, several neuroscience and cell biology experiments have reported that observed statistics of network states can be approximated surprisingly well by maximum entropy models that constrain correlations only within pairs of variables. We would like to verify if this reduction in complexity results from intricacies of biological organization, or if it is a more general attribute of these networks. We generate random networks with p-spin (p > 2) interactions, with N spins and M interaction terms. The probability distribution of the network states is then calculated and approximated with a maximum entropy model based on constraining pairwise spin correlations. Depending on the M/N ratio and the strength of the interaction terms, we observe a transition where the pairwise approximation is very good to a region where it fails. This resembles the sat-unsat transition in constraint satisfaction problems. We argue that the pairwise model works when the number of highly probable states is small. We argue that many biological systems must operate in a strongly constrained regime, and hence we expect the pairwise approximation to be accurate for a wide class of problems. This research has been partially supported by the James S McDonnell Foundation grant No.220020321.
Energy Technology Data Exchange (ETDEWEB)
Kandemir, B S; Keskin, M [Department of Physics, Faculty of Sciences, Ankara University, 06100 Tandogan, Ankara (Turkey)
2008-08-13
In this paper, exact analytical expressions for the entire phonon spectra in single-walled carbon nanotubes with zigzag geometry are presented by using a new approach, originally developed by Kandemir and Altanhan. This approach is based on the concept of construction of a classical lattice Hamiltonian of single-walled carbon nanotubes, wherein the nearest and next nearest neighbor and bond bending interactions are all included, then its quantization and finally diagonalization of the resulting second quantized Hamiltonian. Furthermore, within this context, explicit analytical expressions for the relevant electron-phonon interaction coefficients are also investigated for single-walled carbon nanotubes having this geometry, by the phonon modulation of the hopping interaction.
International Nuclear Information System (INIS)
Kandemir, B S; Keskin, M
2008-01-01
In this paper, exact analytical expressions for the entire phonon spectra in single-walled carbon nanotubes with zigzag geometry are presented by using a new approach, originally developed by Kandemir and Altanhan. This approach is based on the concept of construction of a classical lattice Hamiltonian of single-walled carbon nanotubes, wherein the nearest and next nearest neighbor and bond bending interactions are all included, then its quantization and finally diagonalization of the resulting second quantized Hamiltonian. Furthermore, within this context, explicit analytical expressions for the relevant electron-phonon interaction coefficients are also investigated for single-walled carbon nanotubes having this geometry, by the phonon modulation of the hopping interaction
Sarkar, Niladri
2018-02-01
Using self-consistent Non-Equilibrium Green's Function formalism, the effect of the inelastic scattering due to electron-phonon interaction on the transfer and output characteristics of a coaxially gated generic nanowire field effect transistor has been studied in detail. The scattering strength Do is varied from 0.003 eV2 to 0.3 eV2. There is change in the threshold voltage and suppression of channel current with increasing scattering strength. We also studied the effect of channel inhomogeneities on electron energy. The channel inhomogeneities are invoked by introducing potential step inside the channel. We study the energy relaxation due to inelastic scattering and channel inhomogeneities by comparing the normalized terminal current per energy for the source and drain terminals.
International Nuclear Information System (INIS)
Zhang, L.
1981-08-01
A method based on the tight-binding approximation is developed to calculate the electron-phonon matrix element for the disordered transition metals. With the method as a basis the experimental Tsub(c) data of the amorphous transition metal superconductors are re-analysed. Some comments on the superconductivity of the disordered materials are given
Bianco, A.; Del Zoppo, M.; Zerbi, G.
2004-01-01
We analyze the infrared and Raman spectra (both experimentally and with the aid of quantum chemical calculations) of a series of polyenals which provide us with the fortunate case of a set of polyene chains with one of the end groups consisting of a C=O group which not only does take part in the conjugation but also pulls electrons from the chain making the whole system highly polar, thus affecting the vibrational transition moments. In the following we show, for the first time, that it is possible to derive experimental phonon dispersion curves and these prove to be different for each chain length. We support our experimental findings with Density Functional Theory quantum chemical calculations which reproduce with sufficient accuracy the IR and Raman spectral pattern and at the same time help in disentangling the assignment of the fine structure observed in the experimental spectra.
D-brane physics. From weak to strong coupling
Energy Technology Data Exchange (ETDEWEB)
Vieira Lopes, Daniel Ordine
2013-01-10
In this thesis we discuss two aspects of branes relevant to high-energy phenomenology. First, we consider a single D6-brane wrapping a special Lagrangian cycle and the background space compactified in a Calabi-Yau orientifold the conditions needed to obtain a four-dimensional N=1 supersymmetric theory. We calculate the bosonic part of the effective action by performing a Kaluza-Klein reduction of the brane seven-dimensional action, and obtain the N=1 characteristic data. To discuss the moduli, we first fix the moduli from deformations of the background Calabi-Yau and study the D-brane deformation moduli space. We next allow for Calabi-Yau deformations, and show that the moduli space for complex structure deformations is corrected by the fields living on the D6-brane. We also calculate the scalar potential from D- and F-terms generated from brane and background configurations that would break the supersymmetry condition. We then, via Mirror Symmetry, relate the spectrum obtained in our work to the spectrum in Type IIB effective theory with D3- D5- and D7-branes, and we propose a Kaehler potential for the moduli space of brane deformations in Type IIB theories. In the second part of the thesis we discuss effects of brane intersections when the string coupling can become strong, and we work in the framework of F-theory. After reviewing the basics of F-theory constructions and a particular SU(5) model already discussed in the literature, we construct a model which contains a point of E{sub 8} singularity, and curves of E{sub 6} singularity. By explicitly resolving the space, we show that the resolution requires the introduction of higher dimensional fibers, and argue how we can circumvent this problem for the E{sub 6} curve, leading to the expected resolution that generate an E{sub 6} group, while at the E{sub 8} point we cannot make the resolution lead to an expected E{sub 8} structure.
Strong coupling of collection of emitters on hyperbolic meta-material
Biehs, Svend-Age; Xu, Chenran; Agarwal, Girish S.
2018-04-01
Recently, considerable effort has been devoted to the realization of a strong coupling regime of the radiation matter interaction in the context of an emitter at a meta surface. The strong interaction is well realized in cavity quantum electrodynamics, which also show that strong coupling is much easier to realize using a collection of emitters. Keeping this in mind, we study if emitters on a hyperbolic meta materials can yield a strong coupling regime. We show that strong coupling can be realized for densities of emitters exceeding a critical value. A way to detect strong coupling between emitters and hyperbolic metamaterials is to use the Kretschman-Raether configuration. The strong coupling appears as the splitting of the reflectivity dip. In the weak coupling regime, the dip position shifts. The shift and splitting can be used to sense active molecules at surfaces.
Strongly coupled partitioned FSI using proper orthogonal decomposition
CSIR Research Space (South Africa)
Bogaers, Alfred EJ
2012-12-01
Full Text Available that this dependence on the number of retained histories is due to a trade-off between increasingly ill-conditioned interface Jacobian, when too many histories are retained and sub-optimal coupling convergence rates due to a loss of information when histories...
Strongly coupled, low noise DC-SQUID amplifiers
Pleikies, J.
2009-01-01
The dc Superconducting Quantum Interference Device (dc-SQUID) is one of the most sensitive magnetic field sensors available. In this thesis we concentrate on its application as an amplifier. In this configuration, an input circuit of interest can be connected by means of a coupling coil. The
Strong Carrier–Phonon Coupling in Lead Halide Perovskite Nanocrystals
2017-01-01
We highlight the importance of carrier–phonon coupling in inorganic lead halide perovskite nanocrystals. The low-temperature photoluminescence (PL) spectrum of CsPbBr3 has been investigated under a nonresonant and a nonstandard, quasi-resonant excitation scheme, and phonon replicas of the main PL band have been identified as due to the Fröhlich interaction. The energy of longitudinal optical (LO) phonons has been determined from the separation of the zero phonon band and phonon replicas. We reason that the observed LO phonon coupling can only be related to an orthorhombically distorted crystal structure of the perovskite nanocrystals. Additionally, the strength of carrier–phonon coupling has been characterized using the ratio between the intensities of the first phonon replica and the zero-phonon band. PL emission from localized versus delocalized carriers has been identified as the source of the observed discrepancies between the LO phonon energy and phonon coupling strength under quasi-resonant and nonresonant excitation conditions, respectively. PMID:29019652
Strong Carrier-Phonon Coupling in Lead Halide Perovskite Nanocrystals
Iaru, Claudiu M; Geuchies, Jaco J|info:eu-repo/dai/nl/370526090; Koenraad, Paul M; Vanmaekelbergh, Daniël|info:eu-repo/dai/nl/304829137; Silov, Andrei Yu
2017-01-01
We highlight the importance of carrier-phonon coupling in inorganic lead halide perovskite nanocrystals. The low-temperature photoluminescence (PL) spectrum of CsPbBr3 has been investigated under a nonresonant and a nonstandard, quasi-resonant excitation scheme, and phonon replicas of the main PL
Topologically distinct Feynman diagrams for mass operator in electron-phonon interaction
Directory of Open Access Journals (Sweden)
C.C. Tovstyuk
2009-01-01
Full Text Available The new method for designing topologically distinct Feynman diagrams for electron's mass operator in electron-phonon interaction is developed using the permutation group theory. The carried out classification of DPs allows to choose the classes, corresponding to disconnected diagrams, to singly connected diagrams, direct ("tadpole" diagrams, to diagrams corresponding to phonon Green functions. After this classification the set of considered double permutations is reduced to one class since only these are relevant to mass operator. We derive analytical expressions which allow to identify the DP, and to choose the phonon components, which are not accepted in every type. To avoid repetition of asymmetric diagrams, which correspond to the same analytical expression, we introduce the procedure of inversion in phonon component, and identify symmetric as well as a pair of asymmetric phonon components. For every type of DP (denoted by its digital encoding, taking into account its symmetry, we perform a set of transformations on this DP, list all DPs of the type and all the corresponding Feynman diagrams of mass operator automatically. It is clear that no more expressions (diagrams for the relevant order of perturbation theory for mass operator can be designed.
Anisotropic Electron-Photon and Electron-Phonon Interactions in Black Phosphorus.
Ling, Xi; Huang, Shengxi; Hasdeo, Eddwi H; Liang, Liangbo; Parkin, William M; Tatsumi, Yuki; Nugraha, Ahmad R T; Puretzky, Alexander A; Das, Paul Masih; Sumpter, Bobby G; Geohegan, David B; Kong, Jing; Saito, Riichiro; Drndic, Marija; Meunier, Vincent; Dresselhaus, Mildred S
2016-04-13
Orthorhombic black phosphorus (BP) and other layered materials, such as gallium telluride (GaTe) and tin selenide (SnSe), stand out among two-dimensional (2D) materials owing to their anisotropic in-plane structure. This anisotropy adds a new dimension to the properties of 2D materials and stimulates the development of angle-resolved photonics and electronics. However, understanding the effect of anisotropy has remained unsatisfactory to date, as shown by a number of inconsistencies in the recent literature. We use angle-resolved absorption and Raman spectroscopies to investigate the role of anisotropy on the electron-photon and electron-phonon interactions in BP. We highlight, both experimentally and theoretically, a nontrivial dependence between anisotropy and flake thickness and photon and phonon energies. We show that once understood, the anisotropic optical absorption appears to be a reliable and simple way to identify the crystalline orientation of BP, which cannot be determined from Raman spectroscopy without the explicit consideration of excitation wavelength and flake thickness, as commonly used previously.
Electron-phonon interaction and nonlinear transport phenomena in solid Hg point-contacts
Energy Technology Data Exchange (ETDEWEB)
Khotkevych, V V [Department of Physics, University of Bath, Claverton Down, BA2 7AY Bath (United Kingdom); Khotkevych, N V [Department of Physics, Karazin National University, 61077 Kharkiv (Ukraine); Morlok, S V [National Technical University, 61002, Kharkiv (Ukraine); Konopatskyi, B L; Khotkevych, A V [B.Verkin Institute for Low Temperature Physics and Engineering, 61103 Kharkiv (Ukraine)], E-mail: V.Khotkevych@bath.ac.uk
2009-02-01
At cryogenic temperatures the conductivity of Hg point-contacts was studied in both the superconducting and normal state. An original method of fabricating the Hg-based point-contacts directly in liquid {sup 4}He was proposed, which guaranteed creation of small-size high-purity ballistic contacts. The resistance of the contacts as well as the current-voltage characteristics along with the voltage dependence of their first and second derivatives were experimentally investigated at 1.5 K. We analyze such characteristics of the contacts as Josephson critical current, excess current, energy gap and the nonlinear part of conductivity caused by electron-phonon interaction (EPI). The point-contact EPI function g{sub pc}({omega}) for Hg was reconstructed and integral parameters of EPI were calculated. The g{sub pc}({omega}) was then used as an approximation to the phonon density of states for estimations of the thermodynamic characteristics in Hg. Finally we discuss the results of our calculations of non-linear conductivity caused by manifestation of the frequency dependence of the energy gap function in the elastic current component through the contact.
Modelling of strongly coupled particle growth and aggregation
International Nuclear Information System (INIS)
Gruy, F; Touboul, E
2013-01-01
The mathematical modelling of the dynamics of particle suspension is based on the population balance equation (PBE). PBE is an integro-differential equation for the population density that is a function of time t, space coordinates and internal parameters. Usually, the particle is characterized by a unique parameter, e.g. the matter volume v. PBE consists of several terms: for instance, the growth rate and the aggregation rate. So, the growth rate is a function of v and t. In classical modelling, the growth and the aggregation are independently considered, i.e. they are not coupled. However, current applications occur where the growth and the aggregation are coupled, i.e. the change of the particle volume with time is depending on its initial value v 0 , that in turn is related to an aggregation event. As a consequence, the dynamics of the suspension does not obey the classical Von Smoluchowski equation. This paper revisits this problem by proposing a new modelling by using a bivariate PBE (with two internal variables: v and v 0 ) and by solving the PBE by means of a numerical method and Monte Carlo simulations. This is applied to a physicochemical system with a simple growth law and a constant aggregation kernel.
Static and Dynamic Amplification Using Strong Mechanical Coupling
Ilyas, Saad
2016-07-28
Amplifying the signal-to-noise ratio of resonant sensors is vital toward the effort to miniaturize devices into the sub-micro and nano regimes. In this paper, we demonstrate theoretically and experimentally, amplification through mechanically coupled microbeams. The device is composed of two identical clamped-clamped beams, made of polyimide, connected at their middle through a third beam, which acts as a mechanical coupler. Each of the clamped-clamped microbeams and the coupler are designed to be actuated separately, hence providing various possibilities of actuation and sensing. The coupled resonator is driven into resonance near its first resonance mode and its dynamic behavior is explored via frequency sweeps. The results show significant amplification in the resonator amplitude when the signal is measured at the midpoint of the coupler compared with the response of the individual uncoupled beams. The static pull-in characteristics of the resonator are also studied. It is shown that the compliant mechanical coupler can serve as a low-power radio frequency switch actuated at low voltage loads. [2016-0100
Thermodynamics and instabilities of a strongly coupled anisotropic plasma
Mateos, David; Trancanelli, Diego
2011-07-01
We extend our analysis of a IIB supergravity solution dual to a spatially anisotropic finite-temperature mathcal{N} = 4 super Yang-Mills plasma. The solution is static, possesses an anisotropic horizon, and is completely regular. The full geometry can be viewed as a renormalization group flow from an AdS geometry in the ultraviolet to a Lifshitz-like geometry in the infrared. The anisotropy can be equivalently understood as resulting from a position-dependent θ-term or from a non-zero number density of dissolved D7-branes. The holographic stress tensor is conserved and anisotropic. The presence of a conformal anomaly plays an important role in the thermodynamics. The phase diagram exhibits homogeneous and inhomogeneous (i.e. mixed) phases. In some regions the homogeneous phase displays instabilities reminiscent of those of weakly coupled plasmas. We comment on similarities with QCD at finite baryon density and with the phenomenon of cavitation.
Clean HMBC: Suppression of strong-coupling induced artifacts in HMBC spectra
DEFF Research Database (Denmark)
Würtz, Peter; Permi, Perttu; Nielsen, Niels Chr.
2008-01-01
in HMBC spectra, but they have apparently been overlooked, presumably because they have been assigned to inefficiency of low-pass J filters or not noticed because of a coarse digital resolution in the spectra. Clean HMBC is the HMBC technique of choice for molecules notorious for strong coupling among......A new experiment, clean HMBC, is introduced for suppression of strong-coupling induced artifacts in HMBC spectra. The culprits of these artifacts are an inherent shortcoming of low-pass J filters in the presence of strong coupling and the 1H p pulse in the middle of the evolution period aimed...... at suppressing evolution under heteronuclear J couplings and 1H chemical shifts. A p pulse causes coherence transfer in strongly coupled spin systems and, as is well known in e.g., homonuclear J spectra, this leads to peaks that would not be there in the absence of strong coupling. Similar artifacts occur...
Strongly Coupled Magnetic and Electronic Transitions in Multivalent Strontium Cobaltites
Lee, J. H.; Choi, Woo Seok; Jeen, H.; Lee, H.-J.; Seo, J. H.; Nam, J.; Yeom, M. S.; Lee, H. N.
2017-01-01
The topotactic phase transition in SrCoO x (x = 2.5–3.0) makes it possible to reversibly transit between the two distinct phases, i.e. the brownmillerite SrCoO2.5 that is a room-temperature antiferromagnetic insulator (AFM-I) and the perovskite SrCoO3 that is a ferromagnetic metal (FM-M), owing to their multiple valence states. For the intermediate x values, the two distinct phases are expected to strongly compete with each other. With oxidation of SrCoO2.5, however, it has been conjectured t...
Electron-phonon scattering in indium from r.f. size effect measurements
International Nuclear Information System (INIS)
Hoff, A.B.M.
1977-01-01
The anisotropy of the electron-phonon collison frequency on the second and third zone Fermi surfaces of indium has been determined from the temperature dependence of radiofrequency size effect (R.F.S.E.) line amplitudes. The orbitally-averaged scattering rates turn out to vary with temperature T according to a T 3 -dependence over the entire Fermi surface, except for orbits on the hole surface close to the (100) and (001) symmetry planes. The anomalous temperatue dependences found in the experiments could be attributed to the special circumstances under which the R.F.S.E. was observed. The influences of both the scattering effectiveness and the multiple turns of the electrons on the observed temperature dependence are discussed extensively. For a large number of extreme orbits on the second and third zone Fermi surfaces, the average scattering rates were measured. In order to obtain a functional expression for the local collision frequency over the entire Fermi surface, an inversion technique was used. As a result, it was found that the anisotropy of the collision frequency over the second zone surface is quite high (1:20) whereas the anisotropy over the third zone surface is rather small (<20%). Further, the variation of the scattering rate round the [111]-point on the hole surface could be confirmed by the results of limiting point measurements. The experimental scattering rates at several points on the Fermi surface were compared with theoretical values obtained from a simple two-OPW model calculation. The calculated anisotropy agrees roughly with the experimental one, although locally the actual values can differ by a factor of 2 or more
Inelastic electron scattering influence on the strong coupling oxide superconductors
International Nuclear Information System (INIS)
Gabovich, A.M.; Voitenko, A.I.
1995-01-01
The superconducting order parameters Δ and energy gap Δ g are calculated taking into account the pair-breaking inelastic quasiparticle scattering by thermal Bose-excitations, e.g., phonons. The treatment is self-consistent because the scattering amplitude depends on Δ. The superconducting transition for any strength of the inelastic scattering is the phase transition of the first kind and the dependences Δ (T) and Δ g (T) tend to rectangular curve that agrees well with the experiment for high-Tc oxides. On the basis of the developed theory the nuclear spin-lattice relaxation rate R s in the superconducting state is calculated. The Hebel-Slichter peak in R s (T) is shown to disappear for strong enough inelastic scattering
Thermal DBI action for the D3-brane at weak and strong coupling
DEFF Research Database (Denmark)
Grignani, Gianluca; Harmark, Troels; Marini, Andrea
2014-01-01
We study the effective action for finite-temperature D3-branes with an electromagnetic field at weak and strong coupling. We call this action the thermal DBI action. Comparing at low temperature the leading T4 correction for the thermal DBI action at weak and strong coupling we find that the 3/4 ...
Strong coupling constant extraction from high-multiplicity Z +jets observables
Johnson, Mark; Maître, Daniel
2018-03-01
We present a strong coupling constant extraction at next-to-leading order QCD accuracy using ATLAS Z +2 ,3,4 jets data. This is the first extraction using processes with a dependency on high powers of the coupling constant. We obtain values of the strong coupling constant at the Z mass compatible with the world average and with uncertainties commensurate with other next-to-leading order extractions at hadron colliders. Our most conservative result for the strong coupling constant is αS(MZ)=0.117 8-0.0043+0.0051 .
Strongly coupled dispersed two-phase flows; Ecoulements diphasiques disperses fortement couples
Energy Technology Data Exchange (ETDEWEB)
Zun, I.; Lance, M.; Ekiel-Jezewska, M.L.; Petrosyan, A.; Lecoq, N.; Anthore, R.; Bostel, F.; Feuillebois, F.; Nott, P.; Zenit, R.; Hunt, M.L.; Brennen, C.E.; Campbell, C.S.; Tong, P.; Lei, X.; Ackerson, B.J.; Asmolov, E.S.; Abade, G.; da Cunha, F.R.; Lhuillier, D.; Cartellier, A.; Ruzicka, M.C.; Drahos, J.; Thomas, N.H.; Talini, L.; Leblond, J.; Leshansky, A.M.; Lavrenteva, O.M.; Nir, A.; Teshukov, V.; Risso, F.; Ellinsen, K.; Crispel, S.; Dahlkild, A.; Vynnycky, M.; Davila, J.; Matas, J.P.; Guazelli, L.; Morris, J.; Ooms, G.; Poelma, C.; van Wijngaarden, L.; de Vries, A.; Elghobashi, S.; Huilier, D.; Peirano, E.; Minier, J.P.; Gavrilyuk, S.; Saurel, R.; Kashinsky, O.; Randin, V.; Colin, C.; Larue de Tournemine, A.; Roig, V.; Suzanne, C.; Bounhoure, C.; Brunet, Y.; Tanaka, A.T.; Noma, K.; Tsuji, Y.; Pascal-Ribot, S.; Le Gall, F.; Aliseda, A.; Hainaux, F.; Lasheras, J.; Didwania, A.; Costa, A.; Vallerin, W.; Mudde, R.F.; Van Den Akker, H.E.A.; Jaumouillie, P.; Larrarte, F.; Burgisser, A.; Bergantz, G.; Necker, F.; Hartel, C.; Kleiser, L.; Meiburg, E.; Michallet, H.; Mory, M.; Hutter, M.; Markov, A.A.; Dumoulin, F.X.; Suard, S.; Borghi, R.; Hong, M.; Hopfinger, E.; Laforgia, A.; Lawrence, C.J.; Hewitt, G.F.; Osiptsov, A.N.; Tsirkunov, Yu. M.; Volkov, A.N.
2003-07-01
This document gathers the abstracts of the Euromech 421 colloquium about strongly coupled dispersed two-phase flows. Behaviors specifically due to the two-phase character of the flow have been categorized as: suspensions, particle-induced agitation, microstructure and screening mechanisms; hydrodynamic interactions, dispersion and phase distribution; turbulence modulation by particles, droplets or bubbles in dense systems; collective effects in dispersed two-phase flows, clustering and phase distribution; large-scale instabilities and gravity driven dispersed flows; strongly coupled two-phase flows involving reacting flows or phase change. Topic l: suspensions particle-induced agitation microstructure and screening mechanisms hydrodynamic interactions between two very close spheres; normal stresses in sheared suspensions; a critical look at the rheological experiments of R.A. Bagnold; non-equilibrium particle configuration in sedimentation; unsteady screening of the long-range hydrodynamic interactions of settling particles; computer simulations of hydrodynamic interactions among a large collection of sedimenting poly-disperse particles; velocity fluctuations in a dilute suspension of rigid spheres sedimenting between vertical plates: the role of boundaries; screening and induced-agitation in dilute uniform bubbly flows at small and moderate particle Reynolds numbers: some experimental results. Topic 2: hydrodynamic interactions, dispersion and phase distribution: hydrodynamic interactions in a bubble array; A 'NMR scattering technique' for the determination of the structure in a dispersion of non-brownian settling particles; segregation and clustering during thermo-capillary migration of bubbles; kinetic modelling of bubbly flows; velocity fluctuations in a homogeneous dilute dispersion of high-Reynolds-number rising bubbles; an attempt to simulate screening effects at moderate particle Reynolds numbers using an hybrid formulation; modelling the two
Strong Helioseismic Constraints on Weakly-Coupled Plasmas
Nayfonov, Alan
The extraordinary accuracy of helioseismic data allows detailed theoretical studies of solar plasmas. The necessity to produce solar models matching the experimental results in accuracy imposes strong constrains on the equations of state of solar plasmas. Several discrepancies between the experimental data and models have been successfully identified as the signatures of various non-ideal phenomena. Of a particular interest are questions of the position of the energy levels and the continuum edge and of the effect of the excited states in the solar plasma. Calculations of energy level and continuum shifts, based on the Green function formalism, appeared recently in the literature. These results have been used to examine effects of the shifts on the thermodynamic quantities. A comparison with helioseismic data has shown that the calculations based on lower-level approximations, such as the static screening in the effective two-particle wave equation, agree very well with the experimental data. However, the case of full dynamic screening produces thermodynamic quantities inconsistent with observations. The study of the effect of different internal partition functions on a complete set of thermodynamic quantities has revealed the signature of the excited states in the MHD (Mihalas, Hummer, Dappen) equation of state. The presence of exited states causes a characteristic 'wiggle' in the thermodynamic quantities due to the density-dependent occupation probabilities. This effect is absent if the ACTEX (ACTivity EXpansion) equation of state is used. The wiggle has been found to be most prominent in the quantities sensitive to density. The size of this excited states effect is well within the observational power of helioseismology, and very recent inversion analyses of helioseismic data seem to indicate the presence of the wiggle in the sun. This has a potential importance for the helioseismic determination of the helium abundance of the sun.
Polaronic behavior in a weak-coupling superconductor.
Swartz, Adrian G; Inoue, Hisashi; Merz, Tyler A; Hikita, Yasuyuki; Raghu, Srinivas; Devereaux, Thomas P; Johnston, Steven; Hwang, Harold Y
2018-02-13
The nature of superconductivity in the dilute semiconductor SrTiO 3 has remained an open question for more than 50 y. The extremely low carrier densities ([Formula: see text]-[Formula: see text] cm -3 ) at which superconductivity occurs suggest an unconventional origin of superconductivity outside of the adiabatic limit on which the Bardeen-Cooper-Schrieffer (BCS) and Migdal-Eliashberg (ME) theories are based. We take advantage of a newly developed method for engineering band alignments at oxide interfaces and access the electronic structure of Nb-doped SrTiO 3 , using high-resolution tunneling spectroscopy. We observe strong coupling to the highest-energy longitudinal optic (LO) phonon branch and estimate the doping evolution of the dimensionless electron-phonon interaction strength ([Formula: see text]). Upon cooling below the superconducting transition temperature ([Formula: see text]), we observe a single superconducting gap corresponding to the weak-coupling limit of BCS theory, indicating an order of magnitude smaller coupling ([Formula: see text]). These results suggest that despite the strong normal state interaction with electrons, the highest LO phonon does not provide a dominant contribution to pairing. They further demonstrate that SrTiO 3 is an ideal system to probe superconductivity over a wide range of carrier density, adiabatic parameter, and electron-phonon coupling strength.
Electrically tunable single-dot nanocavities in the weak and strong coupling regimes
DEFF Research Database (Denmark)
Laucht, Arne; Hofbauer, Felix; Angele, Jacob
2008-01-01
We report the design, fabrication and optical investigation of electrically tunable single quantum dot - photonic crystal defect nanocavities [1] operating in both the weak and strong coupling regimes of the light matter interaction. Unlike previous studies, where the dot-cavity spectral detuning...... of the emitted photons from a single-dot nanocavity in the weak and strong coupling regimes. New information is obtained on the nature of the dot-cavity coupling in the weak coupling regime and electrical control of zero dimensional polaritons is demonstrated for the first time. Vacuum Rabi splittings up to 2g...... electrical readout of the strongly coupled dot-cavity system using photocurrent methods will be discussed. This work is financially supported by the DFG via SFB 631 and by the German Excellence Initiative via the “Nanosystems Initiative Munich (NIM)”....
Ratio of bulk to shear viscosity in a quasigluon plasma: from weak to strong coupling
Bluhm, M; Redlich, K
2012-01-01
The ratio of bulk to shear viscosity is expected to exhibit a different behaviour in weakly and in strongly coupled systems. This can be expressed by the dependence of the ratio on the squared sound velocity. In the high temperature QCD plasma at small running coupling, the viscosity ratio is uniquely determined by a quadratic dependence on the conformality measure, whereas in certain strongly coupled and nearly conformal theories this dependence is linear. Employing an effective kinetic theory of quasiparticle excitations with medium-modified dispersion relation, we analyze the ratio of bulk to shear viscosity of the gluon plasma. We show that in this approach the viscosity ratio comprises both dependencies found by means of weak coupling perturbative and strong coupling holographic techniques.
Ricketts, David S.; Chabalko, Matthew J.; Hillenius, Andrew
2013-02-01
In this work, we show experimentally that wireless power transfer (WPT) using strongly coupled magnetic resonance (SCMR) and traditional induction are equivalent. We demonstrate that for a given coil separation, and to within 4%, strongly coupled magnetic resonance and traditional induction produce the same theoretical efficiency of wireless power transfer versus distance. Moreover, we show that the difference between traditional induction and strongly coupled magnetic resonance is in the implementation of the impedance matching network where strongly coupled magnetic resonance uses the mini-loop impedance match. The mini-loop impedance mach provides a low-loss, high-ratio impedance transformation that makes it desirable for longer distance wireless power transfer, where large impedance transformations are needed to maximize power transfer.
Spin-orbit-induced strong coupling of a single spin to a nanomechanical resonator
DEFF Research Database (Denmark)
Pályi, András; Struck, P R; Rudner, Mark
2012-01-01
We theoretically investigate the deflection-induced coupling of an electron spin to vibrational motion due to spin-orbit coupling in suspended carbon nanotube quantum dots. Our estimates indicate that, with current capabilities, a quantum dot with an odd number of electrons can serve....... The strong intrinsic spin-mechanical coupling allows for detection, as well as manipulation of the spin qubit, and may yield enhanced performance of nanotubes in sensing applications....
Extending the reach of strong-coupling: an iterative technique for Hamiltonian lattice models
International Nuclear Information System (INIS)
Alberty, J.; Greensite, J.; Patkos, A.
1983-12-01
The authors propose an iterative method for doing lattice strong-coupling-like calculations in a range of medium to weak couplings. The method is a modified Lanczos scheme, with greatly improved convergence properties. The technique is tested on the Mathieu equation and on a Hamiltonian finite-chain XY model, with excellent results. (Auth.)
Bose condensation in an attractive fermion gas: From weak to strong coupling superconductivity
International Nuclear Information System (INIS)
Nozieres, P.; Schmitt-Rink, S.
1985-01-01
We consider a gas of fermions interacting via an attractive potential. We study the ground state of that system and calculate the critical temperature for the onset of superconductivity as a function of the coupling strength. We compare the behavior of continuum and lattice models and show that the evolution from weak to strong coupling superconductivity is smooth
Zhou, Ning; Yuan, Meng; Gao, Yuhan; Li, Dongsheng; Yang, Deren
2016-04-26
Strong coupling between semiconductor excitons and localized surface plasmons (LSPs) giving rise to hybridized plexciton states in which energy is coherently and reversibly exchanged between the components is vital, especially in the area of quantum information processing from fundamental and practical points of view. Here, in photoluminescence spectra, rather than from common extinction or reflection measurements, we report on the direct observation of Rabi splitting of approximately 160 meV as an indication of strong coupling between excited states of CdSe/ZnS quantum dots (QDs) and LSP modes of silver nanoshells under nonresonant nanosecond pulsed laser excitation at room temperature. The strong coupling manifests itself as an anticrossing-like behavior of the two newly formed polaritons when tuning the silver nanoshell plasmon energies across the exciton line of the QDs. Further analysis substantiates the essentiality of high pump energy and collective strong coupling of many QDs with the radiative dipole mode of the metallic nanoparticles for the realization of strong coupling. Our finding opens up interesting directions for the investigation of strong coupling between LSPs and excitons from the perspective of radiative recombination under easily accessible experimental conditions.
Strong coupling and polariton lasing in Te based microcavities embedding (Cd,Zn)Te quantum wells
Energy Technology Data Exchange (ETDEWEB)
Rousset, J.-G., E-mail: j-g.rousset@fuw.edu.pl; Piętka, B.; Król, M.; Mirek, R.; Lekenta, K.; Szczytko, J.; Borysiuk, J.; Suffczyński, J.; Kazimierczuk, T.; Goryca, M.; Smoleński, T.; Kossacki, P.; Nawrocki, M.; Pacuski, W. [Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, PL-02-093 Warszawa (Poland)
2015-11-16
We report on properties of an optical microcavity based on (Cd,Zn,Mg)Te layers and embedding (Cd,Zn)Te quantum wells. The key point of the structure design is the lattice matching of the whole structure to MgTe, which eliminates the internal strain and allows one to embed an arbitrary number of unstrained quantum wells in the microcavity. We evidence the strong light-matter coupling regime already for the structure containing a single quantum well. Embedding four unstrained quantum wells results in further enhancement of the exciton-photon coupling and the polariton lasing in the strong coupling regime.
Energy Technology Data Exchange (ETDEWEB)
Hensen, Matthias [Institut; Heilpern, Tal [Center; Gray, Stephen K. [Center; Pfeiffer, Walter [Fakultät
2017-10-12
Establishing strong coupling between spatially separated and thus selectively addressable quantum emitters is a key ingredient to complex quantum optical schemes in future technologies. Insofar as many plasmonic nanostructures are concerned, however, the energy transfer and mutual interaction strength between distant quantum emitters can fail to provide strong coupling. Here, based on mode hybridization, the longevity and waveguide character of an elliptical plasmon cavity are combined with intense and highly localized field modes of suitably designed nanoantennas. Based on FDTD simulations a quantum emitter-plasmon coupling strength hg = 16.7 meV is reached while simultaneously keeping a small plasmon resonance line width h gamma(s) = 33 meV. This facilitates strong coupling, and quantum dynamical simulations reveal an oscillatory exchange of excited state population arid a notable degree of entanglement between the quantum emitters spatially separated by 1.8 mu m, i.e., about twice the operating wavelength.
Electron-phonon interactions in manganites: efect on the electronic transport and magnetization
Directory of Open Access Journals (Sweden)
Otero-Leal, M.
2006-06-01
Full Text Available Mixed-valent manganese oxides with perovskite structure offer a certain degree of chemical flexibility that allows making systematic studies of the relationship between the electric and magnetic properties with the crystalline structure. Here we present magnetic measurements in La2/3(Ca1-xSrx1/3MnO3 that demonstrate that the adiabatic approximation breaks down at low x, due to the strong coupling of the electronic and the lattice degrees of freedom.
Los óxidos de manganeso con valencia mixta y estructura de perovskita poseen un cierto grado de flexibilidad química que permite hacer estudios sistemáticos entre las propiedades eléctricas y magnéticas, con la estructura cristalina. En este trabajo presentamos medidas magnéticas en la serie La2/3(Ca1-xSrx1/3MnO3 donde se demuestra que la aproximación adiabática falla para pequeñas x, debido el fuerte acoplamiento de los grados de libertad electrónicos y de la red.
Analog quantum simulation of the Rabi model in the ultra-strong coupling regime.
Braumüller, Jochen; Marthaler, Michael; Schneider, Andre; Stehli, Alexander; Rotzinger, Hannes; Weides, Martin; Ustinov, Alexey V
2017-10-03
The quantum Rabi model describes the fundamental mechanism of light-matter interaction. It consists of a two-level atom or qubit coupled to a quantized harmonic mode via a transversal interaction. In the weak coupling regime, it reduces to the well-known Jaynes-Cummings model by applying a rotating wave approximation. The rotating wave approximation breaks down in the ultra-strong coupling regime, where the effective coupling strength g is comparable to the energy ω of the bosonic mode, and remarkable features in the system dynamics are revealed. Here we demonstrate an analog quantum simulation of an effective quantum Rabi model in the ultra-strong coupling regime, achieving a relative coupling ratio of g/ω ~ 0.6. The quantum hardware of the simulator is a superconducting circuit embedded in a cQED setup. We observe fast and periodic quantum state collapses and revivals of the initial qubit state, being the most distinct signature of the synthesized model.An analog quantum simulation scheme has been explored with a quantum hardware based on a superconducting circuit. Here the authors investigate the time evolution of the quantum Rabi model at ultra-strong coupling conditions, which is synthesized by slowing down the system dynamics in an effective frame.
Room-temperature cavity quantum electrodynamics with strongly coupled Dicke states
Breeze, Jonathan D.; Salvadori, Enrico; Sathian, Juna; Alford, Neil McN.; Kay, Christopher W. M.
2017-09-01
The strong coupling regime is essential for efficient transfer of excitations between states in different quantum systems on timescales shorter than their lifetimes. The coupling of single spins to microwave photons is very weak but can be enhanced by increasing the local density of states by reducing the magnetic mode volume of the cavity. In practice, it is difficult to achieve both small cavity mode volume and low cavity decay rate, so superconducting metals are often employed at cryogenic temperatures. For an ensembles of N spins, the spin-photon coupling can be enhanced by √{N } through collective spin excitations known as Dicke states. For sufficiently large N the collective spin-photon coupling can exceed both the spin decoherence and cavity decay rates, making the strong-coupling regime accessible. Here we demonstrate strong coupling and cavity quantum electrodynamics in a solid-state system at room-temperature. We generate an inverted spin-ensemble with N 1015 by photo-exciting pentacene molecules into spin-triplet states with spin dephasing time T2* 3 μs. When coupled to a 1.45 GHz TE01δ mode supported by a high Purcell factor strontium titanate dielectric cavity (Vm 0.25 cm3, Q 8,500), we observe Rabi oscillations in the microwave emission from collective Dicke states and a 1.8 MHz normal-mode splitting of the resultant collective spin-photon polariton. We also observe a cavity protection effect at the onset of the strong-coupling regime which decreases the polariton decay rate as the collective coupling increases.
International Nuclear Information System (INIS)
Radtke, R.J.; Norman, M.R.
1994-01-01
Recent angle-resolved photoemission (ARPES) experiments have indicated that the electronic dispersion in some of the cuprates possesses an extended saddle point near the Fermi level which gives rise to a density of states that diverges like a power law instead of the weaker logarithmic divergence usually considered. We investigate whether this strong singularity can give rise to high transition temperatures by computing the critical temperature T c and isotope effect coefficient α within a strong-coupling Eliashberg theory which accounts for the full energy variation of the density of states. Using band structures extracted from ARPES measurements, we demonstrate that, while the weak-coupling solutions suggest a strong influence of the strength of the Van Hove singularity on T c and α, strong-coupling solutions show less sensitivity to the singularity strength and do not support the hypothesis that band-structure effects alone can account for either the large T c 's or the different T c 's within the copper oxide family. This conclusion is supported when our results are plotted as a function of the physically relevant self-consistent coupling constant, which shows universal behavior at very strong coupling
Room temperature strong light-matter coupling in three dimensional terahertz meta-atoms
Energy Technology Data Exchange (ETDEWEB)
Paulillo, B., E-mail: bruno.paulillo@u-psud.fr; Manceau, J.-M., E-mail: jean-michel.manceau@u-psud.fr; Colombelli, R., E-mail: raffaele.colombelli@u-psud.fr [Institut d' Electronique Fondamentale, Univ. Paris Sud, UMR8622 CNRS, 91405 Orsay (France); Li, L. H.; Davies, A. G.; Linfield, E. H. [School of Electronic and Electrical Engineering, University of Leeds, Woodhouse Lane, Leeds LS2 9JT (United Kingdom)
2016-03-07
We demonstrate strong light-matter coupling in three dimensional terahertz meta-atoms at room temperature. The intersubband transition of semiconductor quantum wells with a parabolic energy potential is strongly coupled to the confined circuital mode of three-dimensional split-ring metal-semiconductor-metal resonators that have an extreme sub-wavelength volume (λ/10). The frequency of these lumped-element resonators is controlled by the size and shape of the external antenna, while the interaction volume remains constant. This allows the resonance frequency to be swept across the intersubband transition and the anti-crossing characteristic of the strong light-matter coupling regime to be observed. The Rabi splitting, which is twice the Rabi frequency (2Ω{sub Rabi}), amounts to 20% of the bare transition at room temperature, and it increases to 28% at low-temperature.
The Bekenstein bound in strongly coupled O(N) scalar field theory
International Nuclear Information System (INIS)
Magalhaes, T. Santos; Svaiter, N.F.; Menezes, G.
2009-09-01
We discuss the O(N) self-interacting scalar field theory, in the strong-coupling regime and also in the limit of large N. Considering that the system is in thermal equilibrium with a reservoir at temperature β -1 , we assume the presence of macroscopic boundaries conning the field in a hypercube of side L. Using the strong-coupling perturbative expansion, we generalize previous results, i.e., we obtain the renormalized mean energy E and entropy S for the system in rst order of the strong-coupling perturbative expansion, presenting an analytical proof that the specific entropy also satisfies in some situations a quantum bound. When considering the low temperature behavior of the specific entropy, the sign of the renormalized zero-point energy can invalidate this quantum bound. If the renormalized zero point-energy is a positive quantity, at intermediate temperatures and in the low temperature limit, there is a quantum bound. (author)
The strong-weak coupling symmetry in 2D Φ4 field models
Directory of Open Access Journals (Sweden)
B.N.Shalaev
2005-01-01
Full Text Available It is found that the exact beta-function β(g of the continuous 2D gΦ4 model possesses two types of dual symmetries, these being the Kramers-Wannier (KW duality symmetry and the strong-weak (SW coupling symmetry f(g, or S-duality. All these transformations are explicitly constructed. The S-duality transformation f(g is shown to connect domains of weak and strong couplings, i.e. above and below g*. Basically it means that there is a tempting possibility to compute multiloop Feynman diagrams for the β-function using high-temperature lattice expansions. The regular scheme developed is found to be strongly unstable. Approximate values of the renormalized coupling constant g* found from duality symmetry equations are in an agreement with available numerical results.
Ideal gas behavior of a strongly-coupled complex (dusty) plasma
Oxtoby, Neil P.; Griffith, Elias J.; Durniak, Céline; Ralph, Jason F.; Samsonov, Dmitry
2012-01-01
In a laboratory, a two-dimensional complex (dusty) plasma consists of a low-density ionized gas containing a confined suspension of Yukawa-coupled plastic microspheres. For an initial crystal-like form, we report ideal gas behavior in this strongly coupled system during shock-wave experiments. This evidence supports the use of the ideal gas law as the equation of state for soft crystals such as those formed by dusty plasmas.
Plexcitons: The Role of Oscillator Strengths and Spectral Widths in Determining Strong Coupling
Energy Technology Data Exchange (ETDEWEB)
Thomas, Reshmi [School; Thomas, Anoop [School; Pullanchery, Saranya [School; Joseph, Linta [School; Somasundaran, Sanoop Mambully [School; Swathi, Rotti Srinivasamurthy [School; Gray, Stephen K. [Center; Thomas, K. George [School
2018-01-05
Strong coupling interactions between plasmon and exciton-based excitations have been proposed to be useful in the design of optoelectronic systems. However, the role of various optical parameters dictating the plasmon-exciton (plexciton) interactions is less understood. Herein, we propose an inequality for achieving strong coupling between plasmons and excitons through appropriate variation of their oscillator strengths and spectral widths. These aspects are found to be consistent with experiments on two sets of free-standing plexcitonic systems obtained by (i) linking fluorescein isothiocyanate on Ag nanoparticles of varying sizes through silane coupling and (ii) electrostatic binding of cyanine dyes on polystyrenesulfonate-coated Au nanorods of varying aspect ratios. Being covalently linked on Ag nanoparticles, fluorescein isothiocyanate remains in monomeric state, and its high oscillator strength and narrow spectral width enable us to approach the strong coupling limit. In contrast, in the presence of polystyrenesulfonate, monomeric forms of cyanine dyes exist in equilibrium with their aggregates: Coupling is not observed for monomers and H-aggregates whose optical parameters are unfavorable. The large aggregation number, narrow spectral width, and extremely high oscillator strength of J-aggregates of cyanines permit effective delocalization of excitons along the linear assembly of chromophores, which in turn leads to efficient coupling with the plasmons. Further, the results obtained from experiments and theoretical models are jointly employed to describe the plexcitonic states, estimate the coupling strengths, and rationalize the dispersion curves. The experimental results and the theoretical analysis presented here portray a way forward to the rational design of plexcitonic systems attaining the strong coupling limits.
Strong/weak coupling duality relations for non-supersymmetric string theories
International Nuclear Information System (INIS)
Blum, J.D.; Dienes, K.R.
1998-01-01
Both the supersymmetric SO(32) and E 8 x E 8 heterotic strings in ten dimensions have known strong-coupling duals. However, it has not been known whether there also exist strong-coupling duals for the non-supersymmetric heterotic strings in ten dimensions. In this paper, we construct explicit open-string duals for the circle compactifications of several of these non-supersymmetric theories, among them the tachyon-free SO(16) x SO(16) string. Our method involves the construction of heterotic and open-string interpolating models that continuously connect non-supersymmetric strings to supersymmetric strings. We find that our non-supersymmetric dual theories have exactly the same massless spectra as their heterotic counterparts within a certain range of our interpolations. We also develop a novel method for analyzing the solitons of non-supersymmetric open-string theories, and find that the solitons of our dual theories also agree with their heterotic counterparts. These are therefore the first known examples of strong/weak coupling duality relations between non-supersymmetric, tachyon-free string theories. Finally, the existence of these strong-coupling duals allows us to examine the non-perturbative stability of these strings, and we propose a phase diagram for the behavior of these strings as a function of coupling and radius. (orig.)
Cooling in the single-photon strong-coupling regime of cavity optomechanics
Nunnenkamp, A.; Børkje, K.; Girvin, S. M.
2012-05-01
In this Rapid Communication we discuss how red-sideband cooling is modified in the single-photon strong-coupling regime of cavity optomechanics where the radiation pressure of a single photon displaces the mechanical oscillator by more than its zero-point uncertainty. Using Fermi's golden rule we calculate the transition rates induced by the optical drive without linearizing the optomechanical interaction. In the resolved-sideband limit we find multiple-phonon cooling resonances for strong single-photon coupling that lead to nonthermal steady states including the possibility of phonon antibunching. Our study generalizes the standard linear cooling theory.
Angular Structure of Jet Quenching Within a Hybrid Strong/Weak Coupling Model
Casalderrey-Solana, Jorge; Milhano, Guilherme; Pablos, Daniel; Rajagopal, Krishna
2017-01-01
Within the context of a hybrid strong/weak coupling model of jet quenching, we study the modification of the angular distribution of the energy within jets in heavy ion collisions, as partons within jet showers lose energy and get kicked as they traverse the strongly coupled plasma produced in the collision. To describe the dynamics transverse to the jet axis, we add the effects of transverse momentum broadening into our hybrid construction, introducing a parameter $K\\equiv \\hat q/T^3$ that governs its magnitude. We show that, because of the quenching of the energy of partons within a jet, even when $K\
Three-loop Standard Model effective potential at leading order in strong and top Yukawa couplings
Energy Technology Data Exchange (ETDEWEB)
Martin, Stephen P. [Santa Barbara, KITP
2014-01-08
I find the three-loop contribution to the effective potential for the Standard Model Higgs field, in the approximation that the strong and top Yukawa couplings are large compared to all other couplings, using dimensional regularization with modified minimal subtraction. Checks follow from gauge invariance and renormalization group invariance. I also briefly comment on the special problems posed by Goldstone boson contributions to the effective potential, and on the numerical impact of the result on the relations between the Higgs vacuum expectation value, mass, and self-interaction coupling.
Strong enhancement of light-matter interaction in graphene coupled to a photonic crystal nanocavity.
Gan, Xuetao; Mak, Kin Fai; Gao, Yuanda; You, Yumeng; Hatami, Fariba; Hone, James; Heinz, Tony F; Englund, Dirk
2012-11-14
We demonstrate a large enhancement in the interaction of light with graphene through coupling with localized modes in a photonic crystal nanocavity. Spectroscopic studies show that a single atomic layer of graphene reduces the cavity reflection by more than a factor of one hundred, while also sharply reducing the cavity quality factor. The strong interaction allows for cavity-enhanced Raman spectroscopy on subwavelength regions of a graphene sample. A coupled-mode theory model matches experimental observations and indicates significantly increased light absorption in the graphene layer. The coupled graphene-cavity system also enables precise measurements of graphene's complex refractive index.
Thermal conductivity of magnetic insulators with strong spin-orbit coupling
Stamokostas, Georgios; Lapas, Panteleimon; Fiete, Gregory A.
We study the influence of spin-orbit coupling on the thermal conductivity of various types of magnetic insulators. In the absence of spin-orbit coupling and orbital-degeneracy, the strong-coupling limit of Hubbard interactions at half filling can often be adequately described in terms of a pure spin Hamiltonian of the Heisenberg form. However, in the presence of spin-orbit coupling the resulting exchange interaction can become highly anisotropic. The effect of the atomic spin-orbit coupling, taken into account through the effect of magnon-phonon interactions and the magnetic order and excitations, on the lattice thermal conductivity of various insulating magnetic systems is studied. We focus on the regime of low temperatures where the dominant source of scattering is two-magnon scattering to one-phonon processes. The thermal current is calculated within the Boltzmann transport theory. We are grateful for financial support from NSF Grant DMR-0955778.
Strong generalized synchronization with a particular relationship R between the coupled systems
Grácio, Clara; Fernandes, Sara; Mário Lopes, Luís
2018-03-01
The question of the chaotic synchronization of two coupled dynamical systems is an issue that interests researchers in many fields, from biology to psychology, through economics, chemistry, physics, and many others. The different forms of couplings and the different types of synchronization, give rise to many problems, most of them little studied. In this paper we deal with general couplings of two dynamical systems and we study strong generalized synchronization with a particular relationship R between them. Our results include the definition of a window in the domain of the coupling strength, where there is an exponentially stable solution, and the explicit determination of this window. In the case of unidirectional or symmetric couplings, this window is presented in terms of the maximum Lyapunov exponent of the systems. Examples of applications to chaotic systems of dimension one and two are presented.
Chen, Mo; Liu, Chao; Xian, Hao
2015-10-10
High-speed free-space optical communication systems using fiber-optic components can greatly improve the stability of the system and simplify the structure. However, propagation through atmospheric turbulence degrades the spatial coherence of the signal beam and limits the single-mode fiber (SMF) coupling efficiency. In this paper, we analyze the influence of the atmospheric turbulence on the SMF coupling efficiency over various turbulences. The results show that the SMF coupling efficiency drops from 81% without phase distortion to 10% when phase root mean square value equals 0.3λ. The simulations of SMF coupling with adaptive optics (AO) indicate that it is inevitable to compensate the high-order aberrations for SMF coupling over relatively strong turbulence. The SMF coupling efficiency experiments, using an AO system with a 137-element deformable mirror and a Hartmann-Shack wavefront sensor, obtain average coupling efficiency increasing from 1.3% in open loop to 46.1% in closed loop under a relatively strong turbulence, D/r0=15.1.
Sharma, Ramkishor; Jagannathan, Sandhya; Seshadri, T. R.; Subramanian, Kandaswamy
2017-10-01
Models of inflationary magnetogenesis with a coupling to the electromagnetic action of the form f2Fμ νFμ ν , are known to suffer from several problems. These include the strong coupling problem, the backreaction problem and also strong constraints due to the Schwinger effect. We propose a model which resolves all these issues. In our model, the coupling function, f , grows during inflation and transits to a decaying phase post-inflation. This evolutionary behavior is chosen so as to avoid the problem of strong coupling. By assuming a suitable power-law form of the coupling function, we can also neglect backreaction effects during inflation. To avoid backreaction post-inflation, we find that the reheating temperature is restricted to be below ≈1.7 ×104 GeV . The magnetic energy spectrum is predicted to be nonhelical and generically blue. The estimated present day magnetic field strength and the corresponding coherence length taking reheating at the QCD epoch (150 MeV) are 1.4 ×10-12 G and 6.1 ×10-4 Mpc , respectively. This is obtained after taking account of nonlinear processing over and above the flux-freezing evolution after reheating. If we consider also the possibility of a nonhelical inverse transfer, as indicated in direct numerical simulations, the coherence length and the magnetic field strength are even larger. In all cases mentioned above, the magnetic fields generated in our models satisfy the γ -ray bound below a certain reheating temperature.
Strong Coupling of a Quantum Oscillator to a Flux Qubit at Its Symmetry Point
Fedorov, A.; Feofanov, A.K.; Macha, P.; Forn-Díaz, P.; Harmans, C.J.P.M.; Mooij, J.E.
2010-01-01
A flux qubit biased at its symmetry point shows a minimum in the energy splitting (the gap), providing protection against flux noise. We have fabricated a qubit of which the gap can be tuned fast and have coupled this qubit strongly to an LC oscillator. We show full spectroscopy of the
Departures from predicted type II behavior in dirty strong-coupling superconductors
International Nuclear Information System (INIS)
Park, J.C.; Neighbor, J.E.; Shiffman, C.A.
1976-01-01
Calorimetric measurements of the Ginsburg-Landau parameters for Pb-Sn and Pb-Bi alloys show good agreement with the calculations of Rainer and Bergmann for kappa 1 (t)/kappa 1 (1). However, the calculations of Rainer and Usadel for kappa 2 (t)/kappa 2 (1) substantially underestimate the enhancements due to strong-coupling. (Auth.)
Fast-Projectile Stopping Power of Quantal Multicomponent Strongly Coupled Plasmas
International Nuclear Information System (INIS)
Ballester, D.; Tkachenko, I. M.
2008-01-01
The Bethe-Larkin formula for the fast-projectile stopping power is extended to multicomponent plasmas. The results are to contribute to the correct interpretation of the experimental data, which could permit us to test existing and future models of thermodynamic, static, and dynamic characteristics of strongly coupled Coulomb systems
Czech Academy of Sciences Publication Activity Database
Exner, Pavel; Pankrashkin, K.
2014-01-01
Roč. 39, č. 2 (2014), s. 193-212 ISSN 0360-5302 R&D Projects: GA ČR GAP203/11/0701 Institutional support: RVO:61389005 Keywords : Eigenvalue * Schrödinger operator * singular interaction * strong coupling * 35Q40 * 35P15 * 35J10 Subject RIV: BE - Theoretical Physics Impact factor: 1.013, year: 2014
Cusp anomalous dimension in maximally supersymmetric Yang-Mills theory at strong coupling.
Basso, B; Korchemsky, G P; Kotański, J
2008-03-07
We construct an analytical solution to the integral equation which is believed to describe logarithmic growth of the anomalous dimensions of high-spin operators in planar N=4 super Yang-Mills theory and use it to determine the strong coupling expansion of the cusp anomalous dimension.
Measurement of the Strong Coupling Constant from Inclusive Jet Production at the Tevatron Collider
Energy Technology Data Exchange (ETDEWEB)
Mesropian, Christina [Rockefeller Univ., New York, NY (United States)
2000-06-01
We present a measurement of the strong coupling constant from a single observable, the inclusive jet cross section. We use 86 pb^{-1} of data collected with the Collider Detector at Fermilab (CDF) from p$\\bar{p}$ collisions at √s = 1800 GeV. The data was analyzed and experimental systematic uncertainties estimated.
Multi-mode ultra-strong coupling in circuit quantum electrodynamics
Bosman, Sal J.; Gely, Mario F.; Singh, Vibhor; Bruno, Alessandro; Bothner, Daniel; Steele, Gary A.
2017-10-01
With the introduction of superconducting circuits into the field of quantum optics, many experimental demonstrations of the quantum physics of an artificial atom coupled to a single-mode light field have been realized. Engineering such quantum systems offers the opportunity to explore extreme regimes of light-matter interaction that are inaccessible with natural systems. For instance the coupling strength g can be increased until it is comparable with the atomic or mode frequency ωa,m and the atom can be coupled to multiple modes which has always challenged our understanding of light-matter interaction. Here, we experimentally realize a transmon qubit in the ultra-strong coupling regime, reaching coupling ratios of g/ωm = 0.19 and we measure multi-mode interactions through a hybridization of the qubit up to the fifth mode of the resonator. This is enabled by a qubit with 88% of its capacitance formed by a vacuum-gap capacitance with the center conductor of a coplanar waveguide resonator. In addition to potential applications in quantum information technologies due to its small size, this architecture offers the potential to further explore the regime of multi-mode ultra-strong coupling.
Towards corrections to the strong coupling limit of staggered lattice QCD
Fromm, Michael; Philipsen, Owe; de Forcrand, Philippe; Unger, Wolfgang; Miura, Kotaroh
2011-01-01
We report on the first steps of an ongoing project to add gauge observables and gauge corrections to the well-studied strong coupling limit of staggered lattice QCD, which has been shown earlier to be amenable to numerical simulations by the worm algorithm in the chiral limit and at finite density. Here we show how to evaluate the expectation value of the Polyakov loop in the framework of the strong coupling limit at finite temperature, allowing to study confinement properties along with those of chiral symmetry breaking. We find the Polyakov loop to rise smoothly, thus signalling deconfinement. The non-analytic nature of the chiral phase transition is reflected in the derivative of the Polyakov loop. We also discuss how to construct an effective theory for non-zero lattice coupling, which is valid to $O(\\beta)$.
Strong asymmetry for surface modes in nonlinear lattices with long-range coupling
International Nuclear Information System (INIS)
Martinez, Alejandro J.; Vicencio, Rodrigo A.; Molina, Mario I.
2010-01-01
We analyze the formation of localized surface modes on a nonlinear cubic waveguide array in the presence of exponentially decreasing long-range interactions. We find that the long-range coupling induces a strong asymmetry between the focusing and defocusing cases for the topology of the surface modes and also for the minimum power needed to generate them. In particular, for the defocusing case, there is an upper power threshold for exciting staggered modes, which depends strongly on the long-range coupling strength. The power threshold for dynamical excitation of surface modes increases (decreases) with the strength of long-range coupling for the focusing (defocusing) cases. These effects seem to be generic for discrete lattices with long-range interactions.
Strong light-matter coupling from atoms to solid-state systems
2014-01-01
The physics of strong light-matter coupling has been addressed in different scientific communities over the last three decades. Since the early eighties, atoms coupled to optical and microwave cavities have led to pioneering demonstrations of cavity quantum electrodynamics, Gedanken experiments, and building blocks for quantum information processing, for which the Nobel Prize in Physics was awarded in 2012. In the framework of semiconducting devices, strong coupling has allowed investigations into the physics of Bose gases in solid-state environments, and the latter holds promise for exploiting light-matter interaction at the single-photon level in scalable architectures. More recently, impressive developments in the so-called superconducting circuit QED have opened another fundamental playground to revisit cavity quantum electrodynamics for practical and fundamental purposes. This book aims at developing the necessary interface between these communities, by providing future researchers with a robust conceptu...
Energy Technology Data Exchange (ETDEWEB)
Angerer, Andreas, E-mail: andreas.angerer@tuwien.ac.at; Astner, Thomas; Wirtitsch, Daniel; Majer, Johannes, E-mail: johannes.majer@tuwien.ac.at [Vienna Center for Quantum Science and Technology, Atominstitut, TU Wien, Stadionallee 2, 1020 Vienna (Austria); Sumiya, Hitoshi [Sumitomo Electric Industries Ltd., Itami 664-001 (Japan); Onoda, Shinobu [Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Isoya, Junichi [Research Centre for Knowledge Communities, University of Tsukuba, 1-2 Kasuga, Tsukuba, Ibaraki 305-8550 (Japan); Putz, Stefan [Vienna Center for Quantum Science and Technology, Atominstitut, TU Wien, Stadionallee 2, 1020 Vienna (Austria); Department of Physics, Princeton University, Princeton, New Jersey 08544 (United States)
2016-07-18
We design and implement 3D-lumped element microwave cavities that spatially focus magnetic fields to a small mode volume. They allow coherent and uniform coupling to electron spins hosted by nitrogen vacancy centers in diamond. We achieve large homogeneous single spin coupling rates, with an enhancement of more than one order of magnitude compared to standard 3D cavities with a fundamental resonance at 3 GHz. Finite element simulations confirm that the magnetic field distribution is homogeneous throughout the entire sample volume, with a root mean square deviation of 1.54%. With a sample containing 10{sup 17} nitrogen vacancy electron spins, we achieve a collective coupling strength of Ω = 12 MHz, a cooperativity factor C = 27, and clearly enter the strong coupling regime. This allows to interface a macroscopic spin ensemble with microwave circuits, and the homogeneous Rabi frequency paves the way to manipulate the full ensemble population in a coherent way.
Self-induced steps in a small Josephson junction strongly coupled to a multimode resonator
DEFF Research Database (Denmark)
Larsen, A.; Jensen, H. Dalsgaard; Mygind, Jesper
1991-01-01
coupled systems. Based on a single-resonator model, we explain the exceptional size of the steps by the large content of higher harmonics of the Josephson oscillation sustained by the multiple modes of the resonator. The parameters of the junction and the loaded resonator—measured in situ by using......An equally spaced series of very large and nearly constant-voltage self-induced singularities has been observed in the dc I-V characteristics of a small Josephson tunnel junction strongly coupled to a resonant section of a superconducting transmission line. The system allows extremely high values...... of the coupling parameter. The current steps are due to subharmonic parametric excitation of the fundamental mode of the resonator loaded by the junction admittance. Using an applied magnetic field to vary the coupling parameter, we traced out half-integer steps as well as the mode steps known from more weakly...
Strong exciton-photon coupling in organic single crystal microcavity with high molecular orientation
Energy Technology Data Exchange (ETDEWEB)
Goto, Kaname [Department of Electronics, Graduate School of Science and Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585 (Japan); Yamashita, Kenichi, E-mail: yamasita@kit.ac.jp [Faculty of Electrical Engineering and Electronics, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585 (Japan); Yanagi, Hisao [Graduate School of Materials Science, Nara Institute of Science and Technology (NAIST), 8916-5 Takayama, Ikoma, Nara 630-0192 (Japan); Yamao, Takeshi; Hotta, Shu [Faculty of Materials Science and Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585 (Japan)
2016-08-08
Strong exciton-photon coupling has been observed in a highly oriented organic single crystal microcavity. This microcavity consists of a thiophene/phenylene co-oligomer (TPCO) single crystal laminated on a high-reflection distributed Bragg reflector. In the TPCO crystal, molecular transition dipole was strongly polarized along a certain horizontal directions with respect to the main crystal plane. This dipole polarization causes significantly large anisotropies in the exciton transition and optical constants. Especially the anisotropic exciton transition was found to provide the strong enhancement in the coupling with the cavity mode, which was demonstrated by a Rabi splitting energy as large as ∼100 meV even in the “half-vertical cavity surface emitting lasing” microcavity structure.
Simensen, Haakon T.; Linder, Jacob
2018-02-01
We present a theoretical description and numerical simulations of the superconducting transition in hybrid structures including strong spin-orbit interactions. The spin-orbit coupling is taken to be of Rashba type for concreteness, and we allow for an arbitrary magnitude of the spin-orbit strength as well as an arbitrary thickness of the spin-orbit coupled layer. This allows us to make contact with the experimentally relevant case of enhanced interfacial spin-orbit coupling via atomically thin heavy metal layers. We consider both interfacial spin-orbit coupling induced by inversion asymmetry in an S/F junction, as well as in-plane spin-orbit coupling in the ferromagnetic region of an S/F/S and an S/F structure. Both the pair amplitudes, local density of states, and critical temperature show dependency on the Rashba strength and, importantly, the orientation of the exchange field. In general, spin-orbit coupling increases the critical temperature of a proximity system where a magnetic field is present, and enhances the superconducting gap in the density of states. We perform a theoretical derivation which explains these results by the appearance of long-ranged singlet correlations. Our results suggest that Tc in ballistic spin-orbit coupled superconducting structures may be tuned by using only a single ferromagnetic layer.
Variational cluster approximation study of Mott transition with strong spin-orbit coupling
International Nuclear Information System (INIS)
Shirakawa, Tomonori; Watanabe, Hiroshi; Yunoki, Seiji
2011-01-01
Motivated by recent experiments on Sr 2 IrO 4 , the ground state magnetic and electronic structures are studied theoretically for a two-dimensional three-band Hubbard model with strong spin-orbit coupling. To treat spin-orbit coupling, local Coulomb interactions, and band structure effects on the same footing, the variational cluster approximation based on the self-energy functional theory is employed. It is found that for a relatively large coupling region, the ground state is an anisotropic antiferromagnetic Mott insulator of an effective local angular momentum J eff = 1/2 with xy plane as an easy plane. This anisotropy is caused by the strong spin-orbit coupling along with the inter-orbital Hund's coupling. The momentum resolved one-particle excitations are also studied for the Mott insulating phase. It is found that the low-energy one-particle excitations consist mostly of the J eff = 1/2 state, a direct evidence of a novel J eff = 1/2 Mott insulator.
Anisotropic shear viscosity of a strongly coupled non-Abelian plasma from magnetic branes
Critelli, R.; Finazzo, S. I.; Zaniboni, M.; Noronha, J.
2014-09-01
Recent estimates for the electromagnetic fields produced in the early stages of noncentral ultrarelativistic heavy ion collisions indicate the presence of magnetic fields B ˜O(0.1-15mπ2), where mπ is the pion mass. It is then of special interest to study the effects of strong (Abelian) magnetic fields on the transport coefficients of strongly coupled non-Abelian plasmas, such as the quark-gluon plasma formed in heavy ion collisions. In this paper we study the anisotropy in the shear viscosity induced by an external magnetic field in a strongly coupled N =4 super Yang-Mills (SYM) plasma. Due to the spatial anisotropy created by the magnetic field, the most general viscosity tensor of a magnetized plasma has five shear viscosity coefficients and two bulk viscosities. We use the holographic correspondence to evaluate two of the shear viscosities, η⊥≡ηxyxy (perpendicular to the magnetic field) and η∥≡ηxzxz=ηyzyz (parallel to the field). When B ≠0 the shear viscosity perpendicular to the field saturates the viscosity bound η⊥/s=1/(4π), while in the direction parallel to the field the bound is violated since η∥/s<1/(4π). However, the violation of the bound in the case of strongly coupled SYM is minimal even for the largest value of B that can be reached in heavy ion collisions.
Strong coupling in porphyrin J-aggregate excitons and plasmons in nano-void arrays
Ferdele, Stefano; Jose, Bincy; Foster, Robert; Keyes, Tia E.; Rice, James H.
2017-10-01
Active plasmonic nano-void arrays made through colloidal lithography (a cost effective and rapid process) potentially offers opportunities for scalable device design. In this work we demonstrate strong coupling between Bragg-like quadrupole surface plasmon modes in nano-void substrate designs with Frankel excitons in a molecular J-aggregate layer though angular tuning. The enhanced exciton-plasmon coupling creates a Fano like line shape in the differential reflection spectra associated with the formation of new hybrid states, leading to anti-crossing of the upper and lower polaritons with a Rabi frequency of 120 meV.
Study of the Higgs-Yukawa theory in the strong-Yukawa coupling regime
Bulava, John; Hou, George W.S.; Jansen, Karl; Knippschild, Bastian; Lin, C.J.David; Nagai, Kei-Ichi; Nagy, Attila; Ogawa, Kenji; Smigielski, Brian
2011-01-01
In this article, we present an ongoing lattice study of the Higgs-Yukawa model, in the regime of strong-Yukawa coupling, using overlap fermions. We investigated the phase structure in this regime by computing the Higgs vacuum expectation value, and by exploring the finite-size scaling behaviour of the susceptibility corresponding to the magnetisation. Our preliminary results indicate the existence of a second-order phase transition when the Yukawa coupling becomes large enough, at which the Higgs vacuum expectation value vanishes and the susceptibility diverges.
ac Stark shift and dephasing of a superconducting qubit strongly coupled to a cavity field.
Schuster, D I; Wallraff, A; Blais, A; Frunzio, L; Huang, R-S; Majer, J; Girvin, S M; Schoelkopf, R J
2005-04-01
We have performed spectroscopy of a superconducting charge qubit coupled nonresonantly to a single mode of an on-chip resonator. The strong coupling induces a large ac Stark shift in the energy levels of both the qubit and the resonator. The dispersive shift of the resonator frequency is used to nondestructively determine the qubit state. Photon shot noise in the measurement field induces qubit level fluctuations leading to dephasing which is characteristic for the measurement backaction. A crossover in line shape with measurement power is observed and theoretically explained. For weak measurement a long intrinsic dephasing time of T2>200 ns of the qubit is found.
Strong Coupling of Microwave Photons to Antiferromagnetic Fluctuations in an Organic Magnet
Mergenthaler, Matthias; Liu, Junjie; Le Roy, Jennifer J.; Ares, Natalia; Thompson, Amber L.; Bogani, Lapo; Luis, Fernando; Blundell, Stephen J.; Lancaster, Tom; Ardavan, Arzhang; Briggs, G. Andrew D.; Leek, Peter J.; Laird, Edward A.
2017-10-01
Coupling between a crystal of di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium radicals and a superconducting microwave resonator is investigated in a circuit quantum electrodynamics (circuit QED) architecture. The crystal exhibits paramagnetic behavior above 4 K, with antiferromagnetic correlations appearing below this temperature, and we demonstrate strong coupling at base temperature. The magnetic resonance acquires a field angle dependence as the crystal is cooled down, indicating anisotropy of the exchange interactions. These results show that multispin modes in organic crystals are suitable for circuit QED, offering a platform for their coherent manipulation. They also utilize the circuit QED architecture as a way to probe spin correlations at low temperature.
Simple model of a Feshbach resonance in the strong-coupling regime
Wasak, T.; Krych, M.; Idziaszek, Z.; Trippenbach, M.; Avishai, Y.; Band, Y. B.
2014-11-01
We use the dressed potentials obtained in the adiabatic representation of two coupled channels to calculate s -wave Feshbach resonances in a three-dimensional spherically symmetric potential with an open channel interacting with a closed channel. Analytic expressions for the s -wave scattering length a and number of resonances are obtained for a piecewise constant model with a piecewise constant interaction of the open and closed channels near the origin. We show analytically and numerically that, for strong enough coupling strength, Feshbach resonances can exist even when the closed channel does not have a bound state.
International Nuclear Information System (INIS)
Chaturvedi, D.K.; Senatore, G.; Tosi, M.P.
1980-10-01
An analytic theory is presented for the static structure factor of the one-component classical plasma at strong couplings. The theory combines the hard-core model of Gillan for short-range correlations in the Coulomb fluid with a semiempirical representation of intermediate-range correlations, through which the requirement of thermodynamic consistency on the ''compressibility'' and the known equation of state of the system are satisfied. Excellent agreement is found with the available computer simulation data on the structure of the fluid. The approach becomes inapplicable at intermediate and weak couplings where effects of penetration in the Coulomb hole of each particle become important. (author)
Achieving the classical Carnot efficiency in a strongly coupled quantum heat engine
Xu, Y. Y.; Chen, B.; Liu, J.
2018-02-01
Generally, the efficiency of a heat engine strongly coupled with a heat bath is less than the classical Carnot efficiency. Through a model-independent method, we show that the classical Carnot efficiency is achieved in a strongly coupled quantum heat engine. First, we present the first law of quantum thermodynamics in strong coupling. Then, we show how to achieve the Carnot cycle and the classical Carnot efficiency at strong coupling. We find that this classical Carnot efficiency stems from the fact that the heat released in a nonequilibrium process is balanced by the absorbed heat. We also analyze the restrictions in the achievement of the Carnot cycle. The first restriction is that there must be two corresponding intervals of the controllable parameter in which the corresponding entropies of the work substance at the hot and cold temperatures are equal, and the second is that the entropy of the initial and final states in a nonequilibrium process must be equal. Through these restrictions, we obtain the positive work conditions, including the usual one in which the hot temperature should be higher than the cold, and a new one in which there must be an entropy interval at the hot temperature overlapping that at the cold. We demonstrate our result through a paradigmatic model—a two-level system in which a work substance strongly interacts with a heat bath. In this model, we find that the efficiency may abruptly decrease to zero due to the first restriction, and that the second restriction results in the control scheme becoming complex.
Microscopic theory of photon-correlation spectroscopy in strong-coupling semiconductors
Energy Technology Data Exchange (ETDEWEB)
Schneebeli, Lukas
2009-11-27
While many quantum-optical phenomena are already well established in the atomic systems, like the photon antibunching, squeezing, Bose-Einstein condensation, teleportation, the quantum-optical investigations in semiconductors are still at their beginning. The fascinating results observed in the atomic systems inspire physicists to demonstrate similar quantum-optical effects also in the semiconductor systems. In contrast to quantum optics with dilute atomic gases, the semiconductors exhibit a complicated many-body problem which is dominated by the Coulomb interaction between the electrons and holes and by coupling with the semiconductor environment. This makes the experimental observation of similar quantum-optical effects in semiconductors demanding. However, there are already experiments which have verified nonclassical effects in semiconductors. In particular, experiments have demonstrated that semiconductor quantum dots (QDs) can exhibit the single-photon emission and generation of polarization-entangled photon pairs. In fact, both atom and QD systems, embedded within a microcavity, have become versatile platforms where one can perform systematic quantum-optics investigations as well as development work toward quantum-information applications. Another interesting field is the strong-coupling regime in which the light-matter coupling exceeds both the decoherence rate of the atom or QD and the cavity resulting in a reversible dynamics between light and matter excitations. In the strong-coupling regime, the Jaynes-Cummings ladder is predicted and shows a photon-number dependent splitting of the new dressed strong-coupling states which are the polariton states of the coupled light-matter system. Although the semiclassical effect of the vacuum Rabi splitting has already been observed in QDs, the verification of the quantum-mechanical Jaynes-Cummings splitting is still missing mainly due to the dephasing. Clearly, the observation of the Jaynes-Cummings ladder in QDs
Thermal Phase Transitions of Strongly Correlated Bosons with Spin-Orbit Coupling
Hickey, Ciarán; Paramekanti, Arun
2014-12-01
Experiments on ultracold atoms have started to explore lattice effects and thermal fluctuations for two-component bosons with spin-orbit coupling (SOC). Motivated by this, we derive and study a t J model for lattice bosons with equal Rashba-Dresselhaus SOC and strong Hubbard repulsion in a uniform Zeeman magnetic field. Using the Gutzwiller ansatz, we find strongly correlated ground states with stripe superfluid (SF) order. We formulate a finite temperature generalization of the Gutzwiller method, and show that thermal fluctuations in the doped Mott insulator drive a two-step melting of the stripe SF, revealing a wide regime of a stripe normal fluid.
Generic strong coupling behavior of Cooper pairs in the surface of superfluid nuclei
Energy Technology Data Exchange (ETDEWEB)
Pillet, N. [DPTA/Service de Physique nucleaire, CEA/DAM Ile de France, BP12, F-91680 Bruyeres-le-Chatel (France); Sandulescu, N. [DPTA/Service de Physique nucleaire, CEA/DAM Ile de France, BP12, F-91680 Bruyeres-le-Chatel (France)]|[Institute of Physics and Nuclear Engineering, 76900 Bucharest (Romania)]|[Institut de Physique Nucleaire, CNRS, UMR 8608, Orsay, F-91406 (France); Schuck, P. [Institut de Physique Nucleaire, CNRS, UMR 8608, Orsay, F-91406 (France)]|[Universite Paris-Sud, Orsay, F-91505 (France)
2007-01-15
With realistic HFB calculations, using the D1S Gogny force, we reveal a generic behavior of concentration of small sized Cooper pairs (2-3 fm) in the surface of superfluid nuclei. This study confirms and extends previous results given in the literature that use more schematic approaches. It is shown that the strong concentration of pair probability of small Cooper pairs in the nuclear surface is a quite general and generic feature and that nuclear pairing is much closer to the strong coupling regime than previously assumed.
Drag force in strongly coupled { N }=4 supersymmetric Yang–Mills plasma in a magnetic field
Zhang, Zi-qiang; Ma, Ke; Hou, De-fu
2018-02-01
Applying AdS/CFT correspondence, we study the effect of a constant magnetic field { B } on the drag force associated with a heavy quark moving through a strongly-coupled { N }=4 supersymmetric Yang–Mills plasma. The quark is considered moving transverse and parallel to { B }. It is shown that for transverse case, the drag force is linearly dependent on { B } in all regions, while for parallel case, the drag force increases monotonously with increasing { B } and also reveals a linear behavior in the regions of strong { B }. In addition, we find that { B } has a more important effect in the transverse case than for the parallel.
Strong coupling effects between a meta-atom and MIM nanocavity
Directory of Open Access Journals (Sweden)
San Chen
2012-09-01
Full Text Available In this paper, we investigate the strong coupling effects between a meta-atom and a metal-insulator-metal (MIM nanocavity. By changing the meta-atom sizes, we achieve the meta-atomic electric dipole, quadrupole or multipole interaction with the plasmonic nanocavity, in which characteristic anticrossing behaviors demonstrate the occurrence of the strong coupling. The various interactions present obviously different splitting values and behaviors of dependence on the meta-atomic position. The largest Rabi-type splittings, about 360.0 meV and 306.1 meV, have been obtained for electric dipole and quadrupole interaction, respectively. We attribute the large splitting to the highly-confined cavity mode and the large transition dipole of the meta-atom. Also the Rabi-type oscillation in time domain is given.
Review of strongly-coupled composite dark matter models and lattice simulations
Kribs, Graham D.; Neil, Ethan T.
2016-08-01
We review models of new physics in which dark matter arises as a composite bound state from a confining strongly-coupled non-Abelian gauge theory. We discuss several qualitatively distinct classes of composite candidates, including dark mesons, dark baryons, and dark glueballs. We highlight some of the promising strategies for direct detection, especially through dark moments, using the symmetries and properties of the composite description to identify the operators that dominate the interactions of dark matter with matter, as well as dark matter self-interactions. We briefly discuss the implications of these theories at colliders, especially the (potentially novel) phenomenology of dark mesons in various regimes of the models. Throughout the review, we highlight the use of lattice calculations in the study of these strongly-coupled theories, to obtain precise quantitative predictions and new insights into the dynamics.
Equivalence of meson scattering amplitudes in strong coupling lattice and flat space string theory
Armoni, Adi; Ireson, Edwin; Vadacchino, Davide
2018-03-01
We consider meson scattering in the framework of the lattice strong coupling expansion. In particular we derive an expression for the 4-point function of meson operators in the planar limit of scalar Chromodynamics. Interestingly, in the naive continuum limit the expression coincides with an independently known result, that of the worldline formalism. Moreover, it was argued by Makeenko and Olesen that (assuming confinement) the resulting scattering amplitude in momentum space is the celebrated expression proposed by Veneziano several decades ago. This motivates us to also use holography in order to argue that the continuum expression for the scattering amplitude is related to the result obtained from flat space string theory. Our results hint that at strong coupling and large-Nc the naive continuum limit of the lattice formalism can be related to a flat space string theory.
Wilson loop correlators at strong coupling: from matrices to bubbling geometries
Gomis, Jaume; Matsuura, Shunji; Okuda, Takuya; Trancanelli, Diego
2008-08-01
We compute at strong coupling the large N correlation functions of supersymmetric Wilson loops in large representations of the gauge group with local operators of Script N = 4 super Yang-Mills. The gauge theory computation of these correlators is performed using matrix model techniques. We show that the strong coupling correlator of the Wilson loop with the stress tensor computed using the matrix model exactly matches the semiclassical computation of the correlator of the 't Hooft loop with the stress tensor, providing a non-trivial quantitative test of electric-magnetic duality of Script N = 4 super Yang-Mills. We then perform these calculations using the dual bulk gravitational picture, where the Wilson loop is described by a ``bubbling'' geometry. By applying holographic methods to these backgrounds we calculate the Wilson loop correlation functions, finding perfect agreement with our gauge theory results.
Sensitive Detection of Individual Neutral Atoms in a Strong Coupling Cavity QED System
International Nuclear Information System (INIS)
Zhang Peng-Fei; Zhang Yu-Chi; Li Gang; Du Jin-Jin; Zhang Yan-Feng; Guo Yan-Qiang; Wang Jun-Min; Zhang Tian-Cai; Li Wei-Dong
2011-01-01
We experimentally demonstrate real-time detection of individual cesium atoms by using a high-finesse optical micro-cavity in a strong coupling regime. A cloud of cesium atoms is trapped in a magneto-optical trap positioned at 5 mm above the micro-cavity center. The atoms fall down freely in gravitation after shutting off the magneto-optical trap and pass through the cavity. The cavity transmission is strongly affected by the atoms in the cavity, which enables the micro-cavity to sense the atoms individually. We detect the single atom transits either in the resonance or various detunings. The single atom vacuum-Rabi splitting is directly measured to be Ω = 2π × 23.9 MHz. The average duration of atom-cavity coupling of about 110 μs is obtained according to the probability distribution of the atom transits. (fundamental areas of phenomenology(including applications))
Particularities of surface plasmon-exciton strong coupling with large Rabi splitting
International Nuclear Information System (INIS)
Symonds, C; Bonnand, C; Plenet, J C; Brehier, A; Parashkov, R; Lauret, J S; Deleporte, E; Bellessa, J
2008-01-01
This paper presents some of the particularities of the strong coupling regime occurring between surface plasmon (SP) modes and excitons. Two different active materials were deposited on a silver film: a cyanine dye J-aggregate, and a two-dimensional layered perovskite-type semiconductor. The dispersion relations, which are deduced from angular resolved reflectometry spectra, present an anticrossing characteristic of the strong coupling regime. The wavevector is a good parameter to determine the Rabi splitting. Due to the large interaction energies (several hundreds of milli-electron-volts), the calculations at constant angle can induce an overestimation of the Rabi splitting of more than a factor of two. Another property of polaritons based on SP is their nonradiative character. In order to observe the polaritonic emission, it is thus necessary to use particular extraction setups, such as gratings or prisms. Otherwise only the incoherent emission can be detected, very similar to the bare exciton emission
Sakata Memorial KMI Workshop on Origin of Mass and Strong Coupling Gauge Theories
Maskawa, Toshihide; Nojiri, Shin'ichi; Tanabashi, Masaharu; Yamawaki, Koichi
2018-01-01
This volume contains contributions to the workshop, which was largely focused on the strong coupling gauge theories in search for theories beyond the standard model, particularly, the LHC experiments and lattice studies of conformal fixed point. The main topics include walking technicolor and the role of conformality in view of the 125 GeV Higgs as a light composite Higgs (technidilaton, and other composite Higgs, etc.). Nonperturbative studies like lattice simulations and stringy/holographic approaches are extensively discussed in close relation to the phenomenological studies. After the discovery of 125 GeV Higgs at LHC, the central issue of particle physics is now to reveal the dynamical origin of the Higgs itself. One of the possibilities would be the composite Higgs based on the strong coupling gauge theory in the TeV region, such as the technidilaton predicted in walking technicolor with infrared conformality. The volume contains, among others, many of the latest important reports on walking technicolo...
International Nuclear Information System (INIS)
Tzimis, A.; Savvidis, P. G.; Trifonov, A. V.; Ignatiev, I. V.; Christmann, G.; Tsintzos, S. I.; Hatzopoulos, Z.; Kavokin, A. V.
2015-01-01
We report observation of strong light-matter coupling in an AlGaAs microcavity (MC) with an embedded single parabolic quantum well. The parabolic potential is achieved by varying aluminum concentration along the growth direction providing equally spaced energy levels, as confirmed by Brewster angle reflectivity from a reference sample without MC. It acts as an active region of the structure which potentially allows cascaded emission of terahertz (THz) light. Spectrally and time resolved pump-probe spectroscopy reveals characteristic quantum beats whose frequencies range from 0.9 to 4.5 THz, corresponding to energy separation between relevant excitonic levels. The structure exhibits strong stimulated nonlinear emission with simultaneous transition to weak coupling regime. The present study highlights the potential of such devices for creating cascaded relaxation of bosons, which could be utilized for THz emission
Equivalence of meson scattering amplitudes in strong coupling lattice and flat space string theory
Directory of Open Access Journals (Sweden)
Adi Armoni
2018-03-01
Full Text Available We consider meson scattering in the framework of the lattice strong coupling expansion. In particular we derive an expression for the 4-point function of meson operators in the planar limit of scalar Chromodynamics. Interestingly, in the naive continuum limit the expression coincides with an independently known result, that of the worldline formalism. Moreover, it was argued by Makeenko and Olesen that (assuming confinement the resulting scattering amplitude in momentum space is the celebrated expression proposed by Veneziano several decades ago. This motivates us to also use holography in order to argue that the continuum expression for the scattering amplitude is related to the result obtained from flat space string theory. Our results hint that at strong coupling and large-Nc the naive continuum limit of the lattice formalism can be related to a flat space string theory.
Strong-coupling behaviour of two t - J chains with interchain single-electron hopping
International Nuclear Information System (INIS)
Zhang Guangming; Feng Shiping; Yu Lu.
1994-01-01
Using the fermion-spin transformation to implement spin-charge separation of constrained electrons, a model of two t - J chains with interchain single-electron hopping is studied by abelian bosonization. After spin-charge decoupling the charge dynamics can be trivially solved, while the spin dynamics is determined by a strong-coupling fixed point where the correlation functions can be calculated explicitly. This is a generalization of the Luther-Emery line for two-coupled t - J chains. The interchain single-electron hopping changes the asymptotic behaviour of the interchain spin-spin correlation functions and the electron Green function, but their exponents are independent of the coupling strength. (author). 25 refs
Effective hadronic lagrangian in the strong coupling expansion of lattice QCD with Susskind fermions
International Nuclear Information System (INIS)
Azakov, S.I.; Aliev, E.S.
1987-12-01
The effective hadronic action in lattice QCD with U(N) and SU(N) gauge groups and with Susskind fermions is constructed in the framework of the strong coupling approximation. For arbitrary finite (odd) N (in particular N=3) we find an effective potential, vacuum expectation value of the (χ-barχ) and an effective action for the physical meson field π(x). (author). 19 refs
Dynamic properties of one-component strongly coupled plasmas: The sum-rule approach
International Nuclear Information System (INIS)
Arkhipov, Yu. V.; Askaruly, A.; Davletov, A. E.; Ballester, D.; Tkachenko, I. M.; Zwicknagel, G.
2010-01-01
The dynamic characteristics of strongly coupled one-component plasmas are studied within the moment approach. Our results on the dynamic structure factor and the dynamic local-field correction satisfy the sum rules and other exact relations automatically. A quantitative agreement is obtained with numerous simulation data on the plasma dynamic properties, including the dispersion and decay of collective modes. Our approach allows us to correct and complement the results previously found with other treatments.
Strongly coupled chameleon fields: Possible test with a neutron Lloyd's mirror interferometer
Energy Technology Data Exchange (ETDEWEB)
Pokotilovski, Yu.N., E-mail: pokot@nf.jinr.ru [Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region (Russian Federation)
2013-02-26
The consideration of possible neutron Lloyd's mirror interferometer experiment to search for strongly coupled chameleon fields is presented. The chameleon scalar fields were proposed to explain the acceleration of expansion of the Universe. The presence of a chameleon field results in a change of a particle's potential energy in vicinity of a massive body. This interaction causes a phase shift of neutron waves in the interferometer. The sensitivity of the method is estimated.
Breakdown of the 1/N expansion in the continuum limit of strong coupling lattice QCD
International Nuclear Information System (INIS)
Bralic, N.; Pontificia Universidade Catolica de Chile, Santiago. Facultad de Fisica); Loewe, M.
1983-08-01
The restoration of lorentz covariance in the continuum limit of strong coupling lattice QCD is shown to require the breakdown of the 1/N expansion. With the leading 1/N appoximation becoming irrelevant in that limit. To leading order in 1/N lorentz convariance can be restored only as an approximate long distance symmetry a non conventional continuum limit with a non hermitian hamiltonian. (Author) [pt
Fermion bag approach to the sign problem in strongly coupled lattice QED with Wilson fermions
Chandrasekharan, Shailesh; Li, Anyi
2010-01-01
We explore the sign problem in strongly coupled lattice QED with one flavor of Wilson fermions in four dimensions using the fermion bag formulation. We construct rules to compute the weight of a fermion bag and show that even though the fermions are confined into bosons, fermion bags with negative weights do exist. By classifying fermion bags as either simple or complex, we find numerical evidence that complex bags with positive and negative weights come with almost equal probabilities and th...
Room temperature strong light-matter coupling in 3D THz meta-atoms (Conference Presentation)
Paulillo, Bruno; Manceau, Jean-Michel; Li, Lianhe; Linfield, Edmund; Colombelli, Raffaele
2016-04-01
We demonstrate strong light-matter coupling at room temperature in the terahertz (THz) spectral region using 3D meta-atoms with extremely sub-wavelength volumes. Using an air-bridge fabrication scheme, we have implemented sub-wavelength 3D THz micro-resonators that rely on suspended loop antennas connected to semiconductor-filled patch cavities. We have experimentally shown that they possess the functionalities of lumped LC resonators: their frequency response can be adjusted by independently tuning the inductance associated the antenna element or the capacitance provided by the metal-semiconductor-metal cavity. Moreover, the radiation coupling and efficiency can be engineered acting on the design of the loop antenna, similarly to conventional RF antennas. Here we take advantage of this rich playground in the context of cavity electrodynamics/intersubband polaritonics. In the strong light-matter coupling regime, a cavity and a two-level system exchange energy coherently at a characteristic rate called the vacuum Rabi frequency ΩR which is dominant with respect to all other loss mechanisms involved. The signature, in the frequency domain, is the appearance of a splitting between the bare cavity and material system resonances: the new states are called upper and a lower polariton branches. So far, most experimental demonstrations of strong light-matter interaction between an intersubband transition and a deeply sub-wavelength mode in the THz or mid-infrared ranges rely on wavelength-scale or larger resonators such as photonic crystals, diffractive gratings, dielectric micro-cavities or patch cavities. Lately, planar metamaterials have been used to enhance the light-matter interaction and strongly reduce the interaction volume by engineering the electric and magnetic resonances of the individual subwavelength constituents. In this contribution we provide evidence of strong coupling between a THz intersubband transition and an extremely sub-wavelength mode (≈λ/10
Energy Technology Data Exchange (ETDEWEB)
Prajapati, R. P., E-mail: prajapati-iter@yahoo.co.in; Bhakta, S. [Department of Pure and Applied Physics, Guru Ghasidas Central University, Bilaspur-495009 (C.G.) (India); Chhajlani, R. K. [Retired from School of Studies in Physics, Vikram University, Ujjain-456010 (M.P.) (India)
2016-05-15
The influence of dust-neutral collisions, polarization force, and electron radiative condensation is analysed on the Jeans (gravitational) instability of partially ionized strongly coupled dusty plasma (SCDP) using linear perturbation (normal mode) analysis. The Boltzmann distributed ions, dynamics of inertialess electrons, charged dust and neutral particles are considered. Using the plane wave solutions, a general dispersion relation is derived which is modified due to the presence of dust-neutral collisions, strong coupling effect, polarization force, electron radiative condensation, and Jeans dust/neutral frequencies. In the long wavelength perturbations, the Jeans instability criterion depends upon strong coupling effect, polarization interaction parameter, and thermal loss, but it is independent of dust-neutral collision frequency. The stability of the considered configuration is analysed using the Routh–Hurwitz criterion. The growth rates of Jeans instability are illustrated, and stabilizing influence of viscoelasticity and dust-neutral collision frequency while destabilizing effect of electron radiative condensation, polarization force, and Jeans dust-neutral frequency ratio is observed. This work is applied to understand the gravitational collapse of SCDP with dust-neutral collisions.
Constraints on parton distributions and the strong coupling from LHC jet data
Rojo, Juan
2015-11-01
Jet production at hadron colliders provides powerful constraints on the parton distribution functions (PDFs) of the proton, in particular on the gluon PDF. Jet production can also be used to extract the QCD coupling αs(Q) and to test its running with the momentum transfer up to the TeV region. In this review, I summarize the information on PDFs and the strong coupling that has been provided by Run I LHC jet data. First of all, I discuss why jet production is directly sensitive to the gluon and quark PDFs at large-x, and then review the state-of-the-art perturbative calculations for jet production at hadron colliders and the corresponding fast calculations required for PDF fitting. Then I present the results of various recent studies on the impact on PDFs, in particular the gluon, that have been performed using as input jet measurements from ATLAS and CMS. I also review the available determinations of the strong coupling constant based on ATLAS and CMS jet data, with emphasis on the fact that LHC jet data provides, for the first time, a direct test of the αs(Q) running at the TeV scale. I conclude with a brief outlook on possible future developments.
Oblique S and T constraints on electroweak strongly-coupled models with a light Higgs
Energy Technology Data Exchange (ETDEWEB)
Pich, A. [Departament de Física Teòrica, IFIC, Universitat de València - CSIC,Apt. Correus 22085, E-46071 València (Spain); Rosell, I. [Departament de Física Teòrica, IFIC, Universitat de València - CSIC,Apt. Correus 22085, E-46071 València (Spain); Departamento de Ciencias Físicas, Matemáticas y de la Computación,Universidad CEU Cardenal Herrera,c/ Sant Bartomeu 55, E-46115 Alfara del Patriarca, València (Spain); Sanz-Ciller, J.J. [Departamento de Física Teórica, Instituto de Física Teórica,Universidad Autónoma de Madrid - CSIC,c/ Nicolás Cabrera 13-15, E-28049 Cantoblanco, Madrid (Spain)
2014-01-28
Using a general effective Lagrangian implementing the chiral symmetry breaking SU(2){sub L}⊗SU(2){sub R}→SU(2){sub L+R}, we present a one-loop calculation of the oblique S and T parameters within electroweak strongly-coupled models with a light scalar. Imposing a proper ultraviolet behaviour, we determine S and T at next-to-leading order in terms of a few resonance parameters. The constraints from the global fit to electroweak precision data force the massive vector and axial-vector states to be heavy, with masses above the TeV scale, and suggest that the W{sup +}W{sup −} and ZZ couplings of the Higgs-like scalar should be close to the Standard Model value. Our findings are generic, since they only rely on soft requirements on the short-distance properties of the underlying strongly-coupled theory, which are widely satisfied in more specific scenarios.
Ghodrat, Malihe; Naji, Ali; Komaie-Moghaddam, Haniyeh; Podgornik, Rudolf
2015-05-07
We study the effective interaction mediated by strongly coupled Coulomb fluids between dielectric surfaces carrying quenched, random monopolar charges with equal mean and variance, both when the Coulomb fluid consists only of mobile multivalent counterions and when it consists of an asymmetric ionic mixture containing multivalent and monovalent (salt) ions in equilibrium with an aqueous bulk reservoir. We analyze the consequences that follow from the interplay between surface charge disorder, dielectric and salt image effects, and the strong electrostatic coupling that results from multivalent counterions on the distribution of these ions and the effective interaction pressure they mediate between the surfaces. In a dielectrically homogeneous system, we show that the multivalent counterions are attracted towards the surfaces with a singular, disorder-induced potential that diverges logarithmically on approach to the surfaces, creating a singular but integrable counterion density profile that exhibits an algebraic divergence at the surfaces with an exponent that depends on the surface charge (disorder) variance. This effect drives the system towards a state of lower thermal 'disorder', one that can be described by a renormalized temperature, exhibiting thus a remarkable antifragility. In the presence of an interfacial dielectric discontinuity, the singular behavior of counterion density at the surfaces is removed but multivalent counterions are still accumulated much more strongly close to randomly charged surfaces as compared with uniformly charged ones. The interaction pressure acting on the surfaces displays in general a highly non-monotonic behavior as a function of the inter-surface separation with a prominent regime of attraction at small to intermediate separations. This attraction is caused directly by the combined effects from charge disorder and strong coupling electrostatics of multivalent counterions, which dominate the surface-surface repulsion due to
Strong coupling in F-theory and geometrically non-Higgsable seven-branes
Directory of Open Access Journals (Sweden)
James Halverson
2017-06-01
Full Text Available Geometrically non-Higgsable seven-branes carry gauge sectors that cannot be broken by complex structure deformation, and there is growing evidence that such configurations are typical in F-theory. We study strongly coupled physics associated with these branes. Axiodilaton profiles are computed using Ramanujan's theories of elliptic functions to alternative bases, showing explicitly that the string coupling is O(1 in the vicinity of the brane; that it sources nilpotent SL(2,Z monodromy and therefore the associated brane charges are modular; and that essentially all F-theory compactifications have regions with order one string coupling. It is shown that non-perturbative SU(3 and SU(2 seven-branes are related to weakly coupled counterparts with D7-branes via deformation-induced Hanany–Witten moves on (p,q string junctions that turn them into fundamental open strings; only the former may exist for generic complex structure. D3-brane near these and the Kodaira type II seven-branes probe Argyres–Douglas theories. The BPS states of slightly deformed theories are shown to be dyonic string junctions.
Liang, Yongye; Wang, Hailiang; Diao, Peng; Chang, Wesley; Hong, Guosong; Li, Yanguang; Gong, Ming; Xie, Liming; Zhou, Jigang; Wang, Jian; Regier, Tom Z; Wei, Fei; Dai, Hongjie
2012-09-26
Electrocatalyst for oxygen reduction reaction (ORR) is crucial for a variety of renewable energy applications and energy-intensive industries. The design and synthesis of highly active ORR catalysts with strong durability at low cost is extremely desirable but remains challenging. Here, we used a simple two-step method to synthesize cobalt oxide/carbon nanotube (CNT) strongly coupled hybrid as efficient ORR catalyst by directly growing nanocrystals on oxidized multiwalled CNTs. The mildly oxidized CNTs provided functional groups on the outer walls to nucleate and anchor nanocrystals, while retaining intact inner walls for highly conducting network. Cobalt oxide was in the form of CoO due to a gas-phase annealing step in NH(3). The resulting CoO/nitrogen-doped CNT (NCNT) hybrid showed high ORR current density that outperformed Co(3)O(4)/graphene hybrid and commercial Pt/C catalyst at medium overpotential, mainly through a 4e reduction pathway. The metal oxide/carbon nanotube hybrid was found to be advantageous over the graphene counterpart in terms of active sites and charge transport. Last, the CoO/NCNT hybrid showed high ORR activity and stability under a highly corrosive condition of 10 M NaOH at 80 °C, demonstrating the potential of strongly coupled inorganic/nanocarbon hybrid as a novel catalyst system in oxygen depolarized cathode for chlor-alkali electrolysis.
Charging-delay effect on longitudinal dust acoustic shock wave in strongly coupled dusty plasma
International Nuclear Information System (INIS)
Ghosh, Samiran; Gupta, M.R.
2005-01-01
Taking into account the charging-delay effect, the nonlinear propagation characteristics of longitudinal dust acoustic wave in strongly coupled collisional dusty plasma described by generalized hydrodynamic model have been investigated. In the 'hydrodynamic limit', a Korteweg-de Vries Burger (KdVB) equation with a damping term arising due to dust-neutral collision is derived in which the Burger term is proportional to the dissipation due to dust viscosity through dust-dust correlation and charging-delay-induced anomalous dissipation. On the other hand, in the 'kinetic limit', a KdVB equation with a damping term and a nonlocal nonlinear forcing term arising due to memory-dependent strong correlation effect of dust fluid is derived in which the Burger term depends only on the charging-delay-induced dissipation. Numerical solution of integrodifferential equations reveals that (i) dissipation due to dust viscosity and principally due to charging delay causes excitation of the longitudinal dust acoustic shock wave in strongly coupled dusty plasma and (ii) dust-neutral collision does not appear to play any direct role in shock formation. The condition for the generation of shock is also discussed briefly
Weak coupling polaron and Landau-Zener scenario: Qubits modeling
Jipdi, M. N.; Tchoffo, M.; Fokou, I. F.; Fai, L. C.; Ateuafack, M. E.
2017-06-01
The paper presents a weak coupling polaron in a spherical dot with magnetic impurities and investigates conditions for which the system mimics a qubit. Particularly, the work focuses on the Landau-Zener (LZ) scenario undergone by the polaron and derives transition coefficients (transition probabilities) as well as selection rules for polaron's transitions. It is proven that, the magnetic impurities drive the polaron to a two-state superposition leading to a qubit structure. We also showed that the symmetry deficiency induced by the magnetic impurities (strong magnetic field) yields to the banishment of transition coefficients with non-stacking states. However, the transition coefficients revived for large confinement frequency (or weak magnetic field) with the orbital quantum numbers escorting transitions. The polaron is then shown to map a qubit independently of the number of relevant states with the transition coefficients lifted as LZ probabilities and given as a function of the electron-phonon coupling constant (Fröhlich constant).
Treating Sample Covariances for Use in Strongly Coupled Atmosphere-Ocean Data Assimilation
Smith, Polly J.; Lawless, Amos S.; Nichols, Nancy K.
2018-01-01
Strongly coupled data assimilation requires cross-domain forecast error covariances; information from ensembles can be used, but limited sampling means that ensemble derived error covariances are routinely rank deficient and/or ill-conditioned and marred by noise. Thus, they require modification before they can be incorporated into a standard assimilation framework. Here we compare methods for improving the rank and conditioning of multivariate sample error covariance matrices for coupled atmosphere-ocean data assimilation. The first method, reconditioning, alters the matrix eigenvalues directly; this preserves the correlation structures but does not remove sampling noise. We show that it is better to recondition the correlation matrix rather than the covariance matrix as this prevents small but dynamically important modes from being lost. The second method, model state-space localization via the Schur product, effectively removes sample noise but can dampen small cross-correlation signals. A combination that exploits the merits of each is found to offer an effective alternative.
Shear viscosity of strongly coupled N = 4 supersymmetric Yang-Mills plasma.
Policastro, G; Son, D T; Starinets, A O
2001-08-20
Using the anti-de Sitter/conformal field theory correspondence, we relate the shear viscosity eta of the finite-temperature N = 4 supersymmetric Yang-Mills theory in the large N, strong-coupling regime with the absorption cross section of low-energy gravitons by a near-extremal black three-brane. We show that in the limit of zero frequency this cross section coincides with the area of the horizon. From this result we find eta = pi / 8N(2)T3. We conjecture that for finite 't Hooft coupling g(2)(YM)N the shear viscosity is eta = f(g(2)(YM)N)N2T3, where f(x) is a monotonic function that decreases from O(x(-2)ln(-1)(1/x)) at small x to pi/8 when x-->infinity.
Gnoffo, Peter A.; Johnston, Christopher O.
2011-01-01
Implementations of a model for equilibrium, steady-state ablation boundary conditions are tested for the purpose of providing strong coupling with a hypersonic flow solver. The objective is to remove correction factors or film cooling approximations that are usually applied in coupled implementations of the flow solver and the ablation response. Three test cases are considered - the IRV-2, the Galileo probe, and a notional slender, blunted cone launched at 10 km/s from the Earth's surface. A successive substitution is employed and the order of succession is varied as a function of surface temperature to obtain converged solutions. The implementation is tested on a specified trajectory for the IRV-2 to compute shape change under the approximation of steady-state ablation. Issues associated with stability of the shape change algorithm caused by explicit time step limits are also discussed.
Hanle Magnetoresistance in Thin Metal Films with Strong Spin-Orbit Coupling.
Vélez, Saül; Golovach, Vitaly N; Bedoya-Pinto, Amilcar; Isasa, Miren; Sagasta, Edurne; Abadia, Mikel; Rogero, Celia; Hueso, Luis E; Bergeret, F Sebastian; Casanova, Fèlix
2016-01-08
We report measurements of a new type of magnetoresistance in Pt and Ta thin films. The spin accumulation created at the surfaces of the film by the spin Hall effect decreases in a magnetic field because of the Hanle effect, resulting in an increase of the electrical resistance as predicted by Dyakonov [Phys. Rev. Lett. 99, 126601 (2007)]. The angular dependence of this magnetoresistance resembles the recently discovered spin Hall magnetoresistance in Pt/Y(3)Fe(5)O(12) bilayers, although the presence of a ferromagnetic insulator is not required. We show that this Hanle magnetoresistance is an alternative simple way to quantitatively study the coupling between charge and spin currents in metals with strong spin-orbit coupling.
Strong-coupling Bose polarons out of equilibrium: Dynamical renormalization-group approach
Grusdt, Fabian; Seetharam, Kushal; Shchadilova, Yulia; Demler, Eugene
2018-03-01
When a mobile impurity interacts with a surrounding bath of bosons, it forms a polaron. Numerous methods have been developed to calculate how the energy and the effective mass of the polaron are renormalized by the medium for equilibrium situations. Here, we address the much less studied nonequilibrium regime and investigate how polarons form dynamically in time. To this end, we develop a time-dependent renormalization-group approach which allows calculations of all dynamical properties of the system and takes into account the effects of quantum fluctuations in the polaron cloud. We apply this method to calculate trajectories of polarons following a sudden quench of the impurity-boson interaction strength, revealing how the polaronic cloud around the impurity forms in time. Such trajectories provide additional information about the polaron's properties which are challenging to extract directly from the spectral function measured experimentally using ultracold atoms. At strong couplings, our calculations predict the appearance of trajectories where the impurity wavers back at intermediate times as a result of quantum fluctuations. Our method is applicable to a broader class of nonequilibrium problems. As a check, we also apply it to calculate the spectral function and find good agreement with experimental results. At very strong couplings, we predict that quantum fluctuations lead to the appearance of a dark continuum with strongly suppressed spectral weight at low energies. While our calculations start from an effective Fröhlich Hamiltonian describing impurities in a three-dimensional Bose-Einstein condensate, we also calculate the effects of additional terms in the Hamiltonian beyond the Fröhlich paradigm. We demonstrate that the main effect of these additional terms on the attractive side of a Feshbach resonance is to renormalize the coupling strength of the effective Fröhlich model.
Strong coupling on a forbidden transition in strontium and nondestructive atom counting
Norcia, Matthew A.; Thompson, James K.
2016-02-01
We observe strong collective coupling between an optical cavity and the forbidden spin singlet to triplet optical transition S10 to P31 in an ensemble of 88Sr. Despite the transition being 1000 times weaker than a typical dipole transition, we observe a well-resolved vacuum Rabi splitting. We use the observed vacuum Rabi splitting to make nondestructive measurements of atomic population with the equivalent of projection-noise limited sensitivity between subsequent measurements and with minimal heating [lattice clocks by generating entangled states and reducing dead time.
A strongly conservative finite element method for the coupling of Stokes and Darcy flow
Kanschat, G.
2010-08-01
We consider a model of coupled free and porous media flow governed by Stokes and Darcy equations with the Beavers-Joseph-Saffman interface condition. This model is discretized using divergence-conforming finite elements for the velocities in the whole domain. Discontinuous Galerkin techniques and mixed methods are used in the Stokes and Darcy subdomains, respectively. This discretization is strongly conservative in Hdiv(Ω) and we show convergence. Numerical results validate our findings and indicate optimal convergence orders. © 2010 Elsevier Inc.
Radiation of a circulating quark in strongly coupled N = 4 super Yang-Mills theory
Athanasiou, Christiana; Chesler, Paul M.; Liu, Hong; Nickel, Dominik; Rajagopal, Krishna
2010-12-01
The energy density and angular distribution of power radiated by a quark undergoing circular motion in strongly coupled N = 4 supersymmetric Yang-Mills (SYM) theory is computed using gauge/gravity duality. The results are qualitatively similar to that of synchrotron radiation produced by an electron in circular motion in classical electrodynamics: At large velocities the quark emits radiation in a narrow beam along its velocity vector with a characteristic opening angle α˜1/γ and radial thickness scaling like ˜1/γ3.
Measuring the EOS of a Dense, Strongly Coupled Plasma; Description of the Technique
International Nuclear Information System (INIS)
Benage, John F. Jr.; Kyraka, George; Workman, Jonathan; Tierney, Thomas
1997-08-01
This paper describes a new experimental design which we believe can produce reasonably accurate data for the equation of state (EOS) of a dense plasma. This design takes advantage of the standard shock technique used for determining the high pressure EOS of solids. It also utilizes recently developed experimental techniques for producing dense, strongly coupled plasmas as well as new diagnostic techniques for measuring the properties of these plasmas. The results should be able to distinguish among theoretical models for plasmas at just under solid density and temperatures of 10's of eV
DEFF Research Database (Denmark)
Kuznetsov, A.M.; Ulstrup, Jens
2002-01-01
We present a new view and an analytical formalism of electron flow through a donor-acceptor molecule inserted between a pair of metal electrodes. The donor and acceptor levels are strongly coupled to an environmental nuclear continuum. The formalism applies to molecular donor-acceptor systems both...... in vacuum or air, and in aqueous solution under electrochemical potential control. Multifarious patterns of rectified electron flow from the negatively to the positively biased electrode arise. The electronic interaction between the donor and acceptor fragments, mutually and with the electrodes, can be weak...
Global Behavior for a Strongly Coupled Predator-Prey Model with One Resource and Two Consumers
Directory of Open Access Journals (Sweden)
Yujuan Jiao
2012-01-01
Full Text Available We consider a strongly coupled predator-prey model with one resource and two consumers, in which the first consumer species feeds on the resource according to the Holling II functional response, while the second consumer species feeds on the resource following the Beddington-DeAngelis functional response, and they compete for the common resource. Using the energy estimates and Gagliardo-Nirenberg-type inequalities, the existence and uniform boundedness of global solutions for the model are proved. Meanwhile, the sufficient conditions for global asymptotic stability of the positive equilibrium for this model are given by constructing a Lyapunov function.
Analyzing quantum jumps of one and two atoms strongly coupled to an optical cavity
DEFF Research Database (Denmark)
Reick, Sebastian; Mølmer, Klaus; Alt, Wolfgang
2010-01-01
We induce quantum jumps between the hyperfine ground states of one and two cesium atoms, strongly coupled to the mode of a high-finesse optical resonator, and analyze the resulting random telegraph signals. We identify experimental parameters to deduce the atomic spin state nondestructively from...... time-dependent probabilities for the atoms to be in one of the two hyperfine states. This analysis is extended to short time bins where a simple threshold analysis would not yield reasonable results. We discuss the effect of super-Poissonian photon number distributions caused by atomic motion....
Drag force in strongly coupled, anisotropic plasma at finite chemical potential
Energy Technology Data Exchange (ETDEWEB)
Chakraborty, Somdeb; Haque, Najmul [Theory Division, Saha Institute of Nuclear Physics,1/AF Bidhannagar, Kolkata-700 064 (India)
2014-12-30
We employ methods of gauge/string duality to analyze the drag force on a heavy quark moving through a strongly coupled, anisotropic N=4,SU(N) super Yang-Mills plasma in the presence of a finite U(1) chemical potential. We present numerical results valid for any value of the anisotropy parameter and the U(1) charge density and arbitrary direction of the quark velocity with respect to the direction of anisotropy. In the small anisotropy limit we are also able to furnish analytical results.
Imaginary potential in strongly coupled N = 4 SYM plasma in a magnetic field
Zhang, Zi-qiang; Hou, De-fu
2018-03-01
We study the effect of a constant magnetic field on the imaginary part of a quarkonia potential in a strongly-coupled N = 4 SYM plasma. We consider the pair axis to be aligned perpendicularly and parallel to the magnetic field, respectively. For both cases, we find that the presence of the magnetic field tends to enhance the imaginary potential thus decreasing the thermal width. In addition, the magnetic field has a stronger effect on the imaginary potential when the pair axis is perpendicular to the magnetic field rather than parallel.
International Nuclear Information System (INIS)
Szyniszewski, Marcin; Manchester Univ.; Cichy, Krzysztof; Poznan Univ.; Kujawa-Cichy, Agnieszka
2014-10-01
We employ exact diagonalization with strong coupling expansion to the massless and massive Schwinger model. New results are presented for the ground state energy and scalar mass gap in the massless model, which improve the precision to nearly 10 -9 %. We also investigate the chiral condensate and compare our calculations to previous results available in the literature. Oscillations of the chiral condensate which are present while increasing the expansion order are also studied and are shown to be directly linked to the presence of flux loops in the system.
Viscosity calculated in simulations of strongly coupled dusty plasmas with gas friction
International Nuclear Information System (INIS)
Feng Yan; Goree, J.; Liu Bin
2011-01-01
A two-dimensional strongly coupled dusty plasma is modeled using Langevin and frictionless molecular dynamical simulations. The static viscosity η and the wave-number-dependent viscosity η(k) are calculated from the microscopic shear in the random motion of particles. A recently developed method of calculating the wave-number-dependent viscosity η(k) is validated by comparing the results of η(k) from the two simulations. It is also verified that the Green-Kubo relation can still yield an accurate measure of the static viscosity η in the presence of a modest level of friction as in dusty plasma experiments.
Experimental Measurement of Self-Diffusion in a Strongly Coupled Plasma
2016-08-04
and ni for all the analysis regions are shown with vertical error bars representing the standard deviation . ωp and Γi are calculated from Ti and ni for... standard - deviation uncertainties of the mean values, which we use in the main article to calculate the uncer- tainties in hΔvxðtÞiþ=hΔvxð0Þiþ. The fits to...Areas: Atomic and Molecular Physics, Plasma Physics, Statistical Physics I. INTRODUCTION In strongly coupled plasmas [1], the Coulomb interaction energy
The Bethe roots of Regge cuts in strongly coupled N=4 SYM theory
International Nuclear Information System (INIS)
Bartels, J.; Schomerus, V.; Sprenger, M.
2015-01-01
We describe a general algorithm for the computation of the remainder function for n-gluon scattering in multi-Regge kinematics for strongly coupled planar N=4 super Yang-Mills theory. This regime is accessible through the infrared physics of an auxiliary quantum integrable system describing strings in AdS 5 ×S 5 . Explicit formulas are presented for n=6 and n=7 external gluons. Our results are consistent with expectations from perturbative gauge theory. This paper comprises the technical details for the results announced in http://dx.doi.org/10.1007/JHEP10(2014)067.
Analytic properties of the OCP and ionic mixtures in the strongly coupled fluid state
International Nuclear Information System (INIS)
DeWitt, H.E.
1993-01-01
Exact results for the Madelung constants and first order anharmonic energies are given for the inverse power potentials with the Coulomb potential as the softest example. Similar exact results are obtained using the analysis of Rosenfeld on the Γ → ∞ limit for the OCP internal energy, direct correlation function, screening function, and bridge functions. Knowing these exact limits for the fluid phase of the OCP allows one to determine the nature of the thermal corrections to the strongly coupled results. Solutions of the HNC equation modified with the hard sphere bridge function give an example
Intrinsic kinetics in heavy ion reactions in the strong-coupling limit
Energy Technology Data Exchange (ETDEWEB)
Isaev, P.N. (AN SSSR, Novosibirsk. Inst. Yadernoj Fiziki)
1985-02-01
A quantum statistical description is suggested for the intrinsic kinetics of nuclear systems with a strong coupling between the collective (global) dynamics and intrinsic degrees of freedom (for a double nuclear system in heavy ion reactions and mother nucleus at the descent stage of fission). The influence of the ''memory'' of the system concerning pre-history of the kinetic process on the form of the kinetic equation is studied in detail. It is shown that Markov's regime is realized at practically all evolution stages of the double nuclear system (and, certainly, in fission). The kinetic equation is written and discussed in this regime.
Strongly correlated photons generated by coupling a three- or four-level system to a waveguide
Zheng, Huaixiu; Gauthier, Daniel J.; Baranger, Harold U.
2012-04-01
We study the generation of strongly correlated photons by coupling an atom to photonic quantum fields in a one-dimensional waveguide. Specifically, we consider a three-level or four-level system for the atom. Photon-photon bound states emerge as a manifestation of the strong photon-photon correlation mediated by the atom. Effective repulsive or attractive interaction between photons can be produced, causing either suppressed multiphoton transmission (photon blockade) or enhanced multiphoton transmission (photon-induced tunneling). As a result, nonclassical light sources can be generated on demand by sending coherent states into the proposed system. We calculate the second-order correlation function of the transmitted field and observe bunching and antibunching caused by the bound states. Furthermore, we demonstrate that the proposed system can produce photon pairs with a high degree of spectral entanglement, which have a large capacity for carrying information and are important for large-alphabet quantum communication.
Strong coupling operation of a free-electron-laser amplifier with an axial magnetic field
Energy Technology Data Exchange (ETDEWEB)
Rullier, J.L.; Devin, A.; Gardelle, J.; Labrouche, J.; Le Taillandier, P. [Commissariat a lEnergie Atomique, Boite Postale 2, 33114 Le Barp (France); Donohue, J.T. [Centre dEtudes Nucleaires de Bordeaux-Gradignan, Boite Postale 120, 33175 Gradignan (France)
1996-03-01
We present the results of a free-electron-laser (FEL) experiment at 35 GHz, using a strongly relativistic electron beam ({ital T}=1.75 MeV). The electron pulse length is 30 ns full width at half maximum with a peak current of 400 A. The FEL is designed to operate in the high-gain Compton regime, with a negative coupling parameter ({Phi}{lt}0) leading to a strong growth rate. More than 50 MW of rf power in the TE{sub 1}{sub 1} mode (43 dB gain) has been obtained with good reproducibility. The experimental results are in good agreement with predictions made using the three-dimensional stationary simulation code solitude. {copyright} {ital 1996 The American Physical Society.}
Feng, Yan; Lin, Wei; Murillo, M S
2017-11-01
Transport properties of two-dimensional (2D) strongly coupled dusty plasmas have been investigated in detail, but never for viscosity with a strong perpendicular magnetic field; here, we examine this scenario using Langevin dynamics simulations of 2D liquids with a binary Yukawa interparticle interaction. The shear viscosity η of 2D liquid dusty plasma is estimated from the simulation data using the Green-Kubo relation, which is the integration of the shear stress autocorrelation function. It is found that, when a perpendicular magnetic field is applied, the shear viscosity of 2D liquid dusty plasma is modified substantially. When the magnetic field is increased, its viscosity increases at low temperatures, while at high temperatures its viscosity diminishes. It is determined that these different variational trends of η arise from the different behaviors of the kinetic and potential parts of the shear stress under external magnetic fields.
Effective action for superfluid Fermi systems in the strong-coupling limit
International Nuclear Information System (INIS)
Dupuis, N.
2005-01-01
We derive the low-energy effective action for three-dimensional superfluid Fermi systems in the strong-coupling limit, where superfluidity originates from Bose-Einstein condensation of composite bosons. Taking into account density and pairing fluctuations on the same footing, we show that the effective action involves only the fermion density ρ r and its conjugate variable, the phase θ r of the pairing order parameter Δ r . We recover the standard action of a Bose superfluid of density ρ r /2, where the bosons have a mass m B =2m and interact via a repulsive contact potential with amplitude g B =4πa B /m B ,a B =2a (a the s-wave scattering length associated to the fermion-fermion interaction in vacuum). For lattice models, the derivation of the effective action is based on the mapping of the attractive Hubbard model onto the Heisenberg model in a uniform magnetic field, and a coherent state path integral representation of the partition function. The effective description of the Fermi superfluid in the strong-coupling limit is a Bose-Hubbard model with an intersite hopping amplitude t B =J/2 and an on-site repulsive interaction U B =2Jz, where J=4t 2 /U (t and -U are the intersite hopping amplitude and the on-site attraction in the (fermionic) Hubbard model, z the number of nearest-neighbor sites)
Effective action for superfluid Fermi systems in the strong-coupling limit
Dupuis, N.
2005-07-01
We derive the low-energy effective action for three-dimensional superfluid Fermi systems in the strong-coupling limit, where superfluidity originates from Bose-Einstein condensation of composite bosons. Taking into account density and pairing fluctuations on the same footing, we show that the effective action involves only the fermion density ρr and its conjugate variable, the phase θr of the pairing order parameter Δr . We recover the standard action of a Bose superfluid of density ρr/2 , where the bosons have a mass mB=2m and interact via a repulsive contact potential with amplitude gB=4πaB/mB,aB=2a ( a the s -wave scattering length associated to the fermion-fermion interaction in vacuum). For lattice models, the derivation of the effective action is based on the mapping of the attractive Hubbard model onto the Heisenberg model in a uniform magnetic field, and a coherent state path integral representation of the partition function. The effective description of the Fermi superfluid in the strong-coupling limit is a Bose-Hubbard model with an intersite hopping amplitude tB=J/2 and an on-site repulsive interaction UB=2Jz , where J=4t2/U ( t and -U are the intersite hopping amplitude and the on-site attraction in the (fermionic) Hubbard model, z the number of nearest-neighbor sites).
The shot noise of a strongly correlated quantum dot coupled to the Luttinger liquid leads
International Nuclear Information System (INIS)
Yang, Kai-Hua; He, Xian; Wang, Huai-Yu; Liu, Kai-Di; Liu, Bei-Yun
2014-01-01
We study the shot noise of a strongly correlated quantum dot weakly coupled to Luttinger liquid leads in the Kondo regime by means of the extended equation of motion method. A general zero-frequency shot noise formula with good convergence is derived. The shot noise exhibits a non-monotonic dependence on voltage for weak intralead interaction. There is a peak around the Kondo temperature at low voltage when the interaction is very weak, and its height decreases rapidly with the intralead interaction increasing. When the interaction is moderately strong the peak disappears and the shot noise scales as a power law in bias voltage, indicating that the intralead electron interaction suppresses the shot noise. It is possible that the measurements of the shot noise spectrum can extract the information of the intralead interaction. - Highlights: • The shot noise of a dot coupled to Luttinger liquid leads in the Kondo regime. • A shot noise formula is derived. • Intralead interaction suppresses the shot noise. • The noise shows different voltage-dependence for different intralead interaction
Strong coupling of a single photon to a superconducting qubit using circuit quantum electrodynamics.
Wallraff, A; Schuster, D I; Blais, A; Frunzio, L; Huang, R- S; Majer, J; Kumar, S; Girvin, S M; Schoelkopf, R J
2004-09-09
The interaction of matter and light is one of the fundamental processes occurring in nature, and its most elementary form is realized when a single atom interacts with a single photon. Reaching this regime has been a major focus of research in atomic physics and quantum optics for several decades and has generated the field of cavity quantum electrodynamics. Here we perform an experiment in which a superconducting two-level system, playing the role of an artificial atom, is coupled to an on-chip cavity consisting of a superconducting transmission line resonator. We show that the strong coupling regime can be attained in a solid-state system, and we experimentally observe the coherent interaction of a superconducting two-level system with a single microwave photon. The concept of circuit quantum electrodynamics opens many new possibilities for studying the strong interaction of light and matter. This system can also be exploited for quantum information processing and quantum communication and may lead to new approaches for single photon generation and detection.
On Yang--Mills Theories with Chiral Matter at Strong Coupling
Energy Technology Data Exchange (ETDEWEB)
Shifman, M.; /Minnesota U., Theor. Phys. Inst. /Saclay, SPhT; Unsal, Mithat; /SLAC /Stanford U., Phys. Dept.
2008-08-20
Strong coupling dynamics of Yang-Mills theories with chiral fermion content remained largely elusive despite much effort over the years. In this work, we propose a dynamical framework in which we can address non-perturbative properties of chiral, non-supersymmetric gauge theories, in particular, chiral quiver theories on S{sub 1} x R{sub 3}. Double-trace deformations are used to stabilize the center-symmetric vacuum. This allows one to smoothly connect smaller(S{sub 1}) to larger(S{sub 1}) physics (R{sub 4} is the limiting case) where the double-trace deformations are switched off. In particular, occurrence of the mass gap in the gauge sector and linear confinement due to bions are analytically demonstrated. We find the pattern of the chiral symmetry realization which depends on the structure of the ring operators, a novel class of topological excitations. The deformed chiral theory, unlike the undeformed one, satisfies volume independence down to arbitrarily small volumes (a working Eguchi-Kawai reduction) in the large N limit. This equivalence, may open new perspectives on strong coupling chiral gauge theories on R{sub 4}.
Energy Technology Data Exchange (ETDEWEB)
Takamoto, Makoto [Department of Earth and Planetary Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033 (Japan); Lazarian, Alexandre, E-mail: mtakamoto@eps.s.u-tokyo.ac.jp, E-mail: alazarian@facstaff.wisc.edu [Department of Astronomy, University of Wisconsin, 475 North Charter Street, Madison, WI 53706 (United States)
2016-11-10
In this Letter, we report compressible mode effects on relativistic magnetohydrodynamic (RMHD) turbulence in Poynting-dominated plasmas using three-dimensional numerical simulations. We decomposed fluctuations in the turbulence into 3 MHD modes (fast, slow, and Alfvén) following the procedure of mode decomposition in Cho and Lazarian, and analyzed their energy spectra and structure functions separately. We also analyzed the ratio of compressible mode to Alfvén mode energy with respect to its Mach number. We found the ratio of compressible mode increases not only with the Alfvén Mach number, but also with the background magnetization, which indicates a strong coupling between the fast and Alfvén modes. It also signifies the appearance of a new regime of RMHD turbulence in Poynting-dominated plasmas where the fast and Alfvén modes are strongly coupled and, unlike the non-relativistic MHD regime, cannot be treated separately. This finding will affect particle acceleration efficiency obtained by assuming Alfvénic critical-balance turbulence and can change the resulting photon spectra emitted by non-thermal electrons.
Continuum Lowering and Fermi-Surface Rising in Strongly Coupled and Degenerate Plasmas
Hu, S. X.
2017-08-01
Continuum lowering is a well known and important physics concept that describes the ionization potential depression (IPD) in plasmas caused by thermal- or pressure-induced ionization of outer-shell electrons. The existing IPD models are often used to characterize plasma conditions and to gauge opacity calculations. Recent precision measurements have revealed deficits in our understanding of continuum lowering in dense hot plasmas. However, these investigations have so far been limited to IPD in strongly coupled but nondegenerate plasmas. Here, we report a first-principles study of the K -edge shifting in both strongly coupled and fully degenerate carbon plasmas, with quantum molecular dynamics calculations based on the all-electron density-functional theory. The resulting K -edge shifting versus plasma density, as a probe to the continuum lowering and the Fermi-surface rising, is found to be significantly different from predictions of existing IPD models. In contrast, a simple model of "single-atom-in-box," developed in this work, accurately predicts K -edge locations as ab initio calculations provide.
Heavy quark energy loss far from equilibrium in a strongly coupled collision
Chesler, Paul M; Rajagopal, Krishna
2013-01-01
We compute and study the drag force acting on a heavy quark propagating through the matter produced in the collision of two sheets of energy in a strongly coupled gauge theory that can be analyzed holographically. Although this matter is initially far from equilibrium, we find that the equilibrium expression for heavy quark energy loss in a homogeneous strongly coupled plasma with the same instantaneous energy density or pressure as that at the location of the quark describes many qualitative features of our results. One interesting exception is that there is a time delay after the initial collision before the heavy quark energy loss becomes significant. At later times, once a liquid plasma described by viscous hydrodynamics has formed, expressions based upon assuming instantaneous homogeneity and equilibrium provide a semi-quantitative description of our results - as long as the rapidity of the heavy quark is not too large. For a heavy quark with large rapidity, the gradients in the velocity of the hydrodyna...
Infrared exponents and the strong-coupling limit in lattice Landau gauge
International Nuclear Information System (INIS)
Sternbeck, Andre; Smekal, Lorenz von
2010-01-01
We study the gluon and ghost propagators of lattice Landau gauge in the strong-coupling limit β=0 in pure SU(2) lattice gauge theory to find evidence of the conformal infrared behavior of these propagators as predicted by a variety of functional continuum methods for asymptotically small momenta q 2 QCD 2 . In the strong-coupling limit, this same behavior is obtained for the larger values of a 2 q 2 (in units of the lattice spacing a), where it is otherwise swamped by the gauge-field dynamics. Deviations for a 2 q 2 <1 are well parameterized by a transverse gluon mass ∝1/a. Perhaps unexpectedly, these deviations are thus no finite-volume effect but persist in the infinite-volume limit. They furthermore depend on the definition of gauge fields on the lattice, while the asymptotic conformal behavior does not. We also comment on a misinterpretation of our results by Cucchieri and Mendes (Phys. Rev. D 81:016005, 2010). (orig.)
Munson, C P; Taylor, A J; Trainor, R J; Wood, B P; Wysocki, F J
1999-01-01
Summary form only given. Atlas is a high current (~30 MA peak, with a current risetime ~4.5 mu sec), high energy (E/sub stored/=24 MJ, E /sub load/=3-6 MJ), pulsed power facility which is being constructed at Los Alamos National Laboratory with a scheduled completion date in the year 2000. When operational, this facility will provide a platform for experiments in high pressure shocks (>20 Mbar), adiabatic compression ( rho / rho /sub 0/>5, P>10 Mbar), high magnetic fields (~2000 T), high strain and strain rates ( epsilon >200, d epsilon /dt~10/sup 4/ to 10/sup 6/ s/sup -1/), hydrodynamic instabilities of materials in turbulent regimes, magnetized target fusion, equation of state, and strongly coupled plasmas. For the strongly coupled plasma experiments, an auxiliary capacitor bank will be used to generate a moderate density (<0.1 solid), relatively cold (~1 eV) plasma by ohmic heating of a conducting material of interest such as titanium. This target plasma will be compressed against a central column conta...
Chahid, M
2000-01-01
The purpose of the present work is a quantitative study of the spin time relaxation within superweak ferrimagnetic materials exhibiting a paramagnetic-ferrimagnetic transition, when the temperature is changed from an initial value T sub i to a final one T sub f very close to the critical temperature T sub c. From a magnetic point of view, the material under investigation is considered to be made of two strongly coupled paramagnetic sublattices of respective moments phi (cursive,open) Greek and psi. Calculations are made within a Landau mean-field theory, whose free energy involves, in addition to quadratic and quartic terms in both moments phi (cursive,open) Greek and psi, a lowest-order coupling - Cphi (cursive,open) Greek psi, where C<0 stands for the coupling constant measuring the interaction between the two sublattices. We first determine the time dependence of the shifts of the order parameters delta phi (cursive,open) Greek and delta psi from the equilibrium state. We find that this time dependence ...
International Nuclear Information System (INIS)
Gelis, Francois; Venugopalan, Raju
2006-01-01
We develop a formalism for particle production in a field theory coupled to a strong time-dependent external source. An example of such a theory is the color glass condensate. We derive a formula, in terms of cut vacuum-vacuum Feynman graphs, for the probability of producing a given number of particles. This formula is valid to all orders in the coupling constant. The distribution of multiplicities is non-Poissonian, even in the classical approximation. We investigate an alternative method of calculating the mean multiplicity. At leading order, the average multiplicity can be expressed in terms of retarded solutions of classical equations of motion. We demonstrate that the average multiplicity at next-to-leading order can be formulated as an initial value problem by solving equations of motion for small fluctuation fields with retarded boundary conditions. The variance of the distribution can be calculated in a similar fashion. Our formalism therefore provides a framework to compute from first principles particle production in proton-nucleus and nucleus-nucleus collisions beyond leading order in the coupling constant and to all orders in the source density. We also provide a transparent interpretation (in conventional field theory language) of the well-known Abramovsky-Gribov-Kancheli (AGK) cancellations. Explicit connections are made between the framework for multi-particle production developed here and the framework of reggeon field theory
Routine daily physical activity and glucose variations are strongly coupled in adults with T1DM.
Farabi, Sarah S; Carley, David W; Cinar, Ali; Quinn, Lauretta
2015-12-01
Type 1 Diabetes (T1DM) is characterized by altered glucose homeostasis resulting in wide glucose variations throughout a 24-h period. The relationship between routine daily physical activity and glucose variations has not been systematically investigated in adults with T1DM. The objectives of this study were to characterize and quantify the relationship between routine daily activity and glucose variations in a small group of adults with T1DM. Adults with T1DM treated with an insulin pump were recruited for the study. Over a 3-day period, glucose variations were monitored with a continuous glucose monitoring system (CGMS) and routine daily physical activity was assessed using an accelerometer-based physical activity-monitoring band. Simultaneous glucose and physical activity data for one 24-h period were used for analysis. Cross-correlation function and wavelet coherence analyses were employed to quantify the coupling between physical activity and glucose. Twelve subjects were included in the analysis. Cross-correlation function analysis revealed strong coupling between activity and glucose. Wavelet Coherence demonstrated that slower oscillations (120-340 min) of glucose and physical activity exhibited significantly greater coherence (F = 12.6, P < 0.0001) than faster oscillations (10 and 120 min). Physical activity and glucose demonstrate strong time and frequency-dependent coupling throughout a 24-h time period in adults with T1DM. © 2015 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.
Conner, Kyle M; Arostegui, AnnaMaria C; Swanson, Daniel D; Brown, Seth N
2018-03-08
The 2,2'-biphenylene-bridged bis(iminosemiquinone) complexes ( t BuClip)M [ t BuClipH 4 = 4,4'-di- tert-butyl- N, N'-bis(3,5-di- tert-butyl-2-hydroxyphenyl)-2,2'-diaminobiphenyl; M = Pd, Pt] can be reduced to the bis(aminophenoxide) complexes ( t BuClipH 2 )M by reaction with hydrazobenzene (M = Pd) or by catalytic hydrogenation (M = Pt). The palladium complex with one aminophenoxide ligand and one iminosemiquinone ligand, ( t BuClipH)Pd, is generated by comproportionation of ( t BuClip)Pd with ( t BuClipH 2 )Pd in a process that is both slow (0.06 M -1 s -1 in toluene at 23 °C) and only modestly favorable ( K com = 1.9 in CDCl 3 ), indicating that both N-H bonds have essentially the same bond strength. The mono(iminoquinone) complex ( t BuClipH)Pt has not been observed, indicating that the platinum analogue shows no tendency to comproportionate ( K com < 0.1). The average bond dissociation free energies (BDFE) of the complexes have been established by equilibration with suitably substituted hydrazobenzenes, and the palladium bis(iminosemiquinone) is markedly more oxidizing than the platinum compound, with hydrogen transfer from ( t BuClipH 2 )Pt to ( t BuClip)Pd occurring with Δ G° = -8.9 kcal mol -1 . The palladium complex ( t BuClipH 2 )Pd reacts with nitroxyl radicals in two observable steps, with the first hydrogen transfer taking place slightly faster than the second. In the platinum analogue, the first hydrogen transfer is much slower than the second, presumably because the N-H bond in the monoradical complex ( t BuClipH)Pt is unusually weak. Using driving force-rate correlations, it is estimated that this bond has a BDFE of 55.1 kcal mol -1 , which is 7.1 kcal mol -1 weaker than that of the first N-H bond in ( t BuClipH 2 )Pt. The two radical centers in the platinum, but not the palladium, complex thus act in concert with each other and display a strong thermodynamic bias toward two-electron reactivity. The greater thermodynamic and kinetic coupling in
Strong dispersive coupling of a high-finesse cavity to a micromechanical membrane.
Thompson, J D; Zwickl, B M; Jayich, A M; Marquardt, Florian; Girvin, S M; Harris, J G E
2008-03-06
Macroscopic mechanical objects and electromagnetic degrees of freedom can couple to each other through radiation pressure. Optomechanical systems in which this coupling is sufficiently strong are predicted to show quantum effects and are a topic of considerable interest. Devices in this regime would offer new types of control over the quantum state of both light and matter, and would provide a new arena in which to explore the boundary between quantum and classical physics. Experiments so far have achieved sufficient optomechanical coupling to laser-cool mechanical devices, but have not yet reached the quantum regime. The outstanding technical challenge in this field is integrating sensitive micromechanical elements (which must be small, light and flexible) into high-finesse cavities (which are typically rigid and massive) without compromising the mechanical or optical properties of either. A second, and more fundamental, challenge is to read out the mechanical element's energy eigenstate. Displacement measurements (no matter how sensitive) cannot determine an oscillator's energy eigenstate, and measurements coupling to quantities other than displacement have been difficult to realize in practice. Here we present an optomechanical system that has the potential to resolve both of these challenges. We demonstrate a cavity which is detuned by the motion of a 50-nm-thick dielectric membrane placed between two macroscopic, rigid, high-finesse mirrors. This approach segregates optical and mechanical functionality to physically distinct structures and avoids compromising either. It also allows for direct measurement of the square of the membrane's displacement, and thus in principle the membrane's energy eigenstate. We estimate that it should be practical to use this scheme to observe quantum jumps of a mechanical system, an important goal in the field of quantum measurement.
Energy Technology Data Exchange (ETDEWEB)
Meevasana, Warawat
2010-05-26
Much progress has been made recently in the study of the effects of electron-phonon (el-ph) coupling in doped insulators using angle resolved photoemission (ARPES), yielding evidence for the dominant role of el-ph interactions in underdoped cuprates. As these studies have been limited to doped Mott insulators, the important question arises how this compares with doped band insulators where similar el-ph couplings should be at work. The archetypical case is the perovskite SrTiO{sub 3} (STO), well known for its giant dielectric constant of 10000 at low temperature, exceeding that of La{sub 2}CuO{sub 4} by a factor of 500. Based on this fact, it has been suggested that doped STO should be the archetypical bipolaron superconductor. Here we report an ARPES study from high-quality surfaces of lightly doped SrTiO{sub 3}. Comparing to lightly doped Mott insulators, we find the signatures of only moderate electron-phonon coupling: a dispersion anomaly associated with the low frequency optical phonon with a {lambda}{prime} {approx} 0.3 and an overall bandwidth renormalization suggesting an overall {lambda}{prime} {approx} 0.7 coming from the higher frequency phonons. Further, we find no clear signatures of the large pseudogap or small polaron phenomena. These findings demonstrate that a large dielectric constant itself is not a good indicator of el-ph coupling and highlight the unusually strong effects of the el-ph coupling in doped Mott insulators.
Optical investigation of the strong spin-orbit-coupled magnetic semimetal YbMnBi2
Chaudhuri, Dipanjan; Cheng, Bing; Yaresko, Alexander; Gibson, Quinn D.; Cava, R. J.; Armitage, N. P.
2017-08-01
Strong spin-orbit coupling (SOC) can result in ground states with nontrivial topological properties. The situation is even richer in magnetic systems where the magnetic ordering can potentially have strong influence over the electronic band structure. The class of A MnBi2 (A = Sr, Ca) compounds are important in this context as they are known to host massive Dirac fermions with strongly anisotropic dispersion, which is believed to be due to the interplay between strong SOC and magnetic degrees of freedom. We report the optical conductivity of YbMnBi2, a newly discovered member of this family and a proposed Weyl semimetal (WSM) candidate with broken time reversal symmetry. Together with density functional theory (DFT) band-structure calculations, we show that the complex conductivity can be interpreted as the sum of an intraband Drude response and interband transitions. We argue that the canting of the magnetic moments that has been proposed to be essential for the realization of the WSM in an otherwise antiferromagnetically ordered system is not necessary to explain the optical conductivity. We believe our data is explained qualitatively by the uncanted magnetic structure with a small offset of the chemical potential from strict stochiometry. We find no definitive evidence of a bulk Weyl nodes. Instead, we see signatures of a gapped Dirac dispersion, common in other members of A MnBi2 family or compounds with similar 2D network of Bi atoms. We speculate that the evidence for a WSM seen in ARPES arises through a surface magnetic phase. Such an assumption reconciles all known experimental data.
Energy Technology Data Exchange (ETDEWEB)
Weymann, Ireneusz, E-mail: weymann@amu.edu.pl [Faculty of Physics, Adam Mickiewicz University, 61-614 Poznań (Poland)
2015-05-07
We analyze the spin-dependent linear-response transport properties of double quantum dots strongly coupled to external ferromagnetic leads. By using the numerical renormalization group method, we determine the dependence of the linear conductance and tunnel magnetoresistance on the degree of spin polarization of the leads and the position of the double dot levels. We focus on the transport regime where the system exhibits the SU(4) Kondo effect. It is shown that the presence of ferromagnets generally leads the suppression of the linear conductance due to the presence of an exchange field. Moreover, the exchange field gives rise to a transition from the SU(4) to the orbital SU(2) Kondo effect. We also analyze the dependence of the tunnel magnetoresistance on the double dot levels' positions and show that it exhibits a very nontrivial behavior.
Strong correlation between early stage atherosclerosis and electromechanical coupling of aorta
Liu, X. Y.; Yan, F.; Niu, L. L.; Chen, Q. N.; Zheng, H. R.; Li, J. Y.
2016-03-01
Atherosclerosis is the underlying cause of cardiovascular diseases that are responsible for many deaths in the world, and the early diagnosis of atherosclerosis is highly desirable. The existing imaging methods, however, are not capable of detecting the early stage of atherosclerosis development due to their limited spatial resolution. Using piezoresponse force microscopy (PFM), we show that the piezoelectric response of an aortic wall increases as atherosclerosis advances, while the stiffness of the aorta shows a less evident correlation with atherosclerosis. Furthermore, we show that there is strong correlation between the coercive electric field necessary to switch the polarity of the artery and the development of atherosclerosis. Thus by measuring the electromechanical coupling of the aortic wall, it is possible to probe atherosclerosis at the early stage of its development, not only improving the spatial resolution by orders of magnitude, but also providing comprehensive quantitative information on the biomechanical properties of the artery.
Field-theoretic Methods in Strongly-Coupled Models of General Gauge Mediation
Fortin, Jean-Francois
2013-01-01
An often-exploited feature of the operator product expansion (OPE) is that it incorporates a splitting of ultraviolet and infrared physics. In this paper we use this feature of the OPE to perform simple, approximate computations of soft masses in gauge-mediated supersymmetry breaking. The approximation amounts to truncating the OPEs for hidden-sector current-current operator products. Our method yields visible-sector superpartner spectra in terms of vacuum expectation values of a few hidden-sector IR elementary fields. We manage to obtain reasonable approximations to soft masses, even when the hidden sector is strongly coupled. We demonstrate our techniques in several examples, including a new framework where supersymmetry-breaking arises both from a hidden sector and dynamically.
Room temperature strong coupling effects from single ZnO nanowire microcavity
Das, Ayan
2012-05-01
Strong coupling effects in a dielectric microcavity with a single ZnO nanowire embedded in it have been investigated at room temperature. A large Rabi splitting of ?100 meV is obtained from the polariton dispersion and a non-linearity in the polariton emission characteristics is observed at room temperature with a low threshold of 1.63 ?J/cm2, which corresponds to a polariton density an order of magnitude smaller than that for the Mott transition. The momentum distribution of the lower polaritons shows evidence of dynamic condensation and the absence of a relaxation bottleneck. The polariton relaxation dynamics were investigated by timeresolved measurements, which showed a progressive decrease in the polariton relaxation time with increase in polariton density. © 2012 Optical Society of America.
Violation of the Holographic Viscosity Bound in a Strongly Coupled Anisotropic Plasma
Rebhan, Anton; Steineder, Dominik
2012-01-01
We study the conductivity and shear viscosity tensors of a strongly coupled N=4 super-Yang-Mills plasma which is kept anisotropic by a θ parameter that depends linearly on one of the spatial dimensions. Its holographic dual is given by an anisotropic axion-dilaton-gravity background and has recently been proposed by Mateos and Trancanelli as a model for the preequilibrium stage of quark-gluon plasma in heavy-ion collisions. By applying the membrane paradigm which we also check by numerical evaluation of Kubo formula and lowest lying quasinormal modes, we find that the shear viscosity purely transverse to the direction of anisotropy saturates the holographic viscosity bound, whereas longitudinal shear viscosities are smaller, providing the first such example not involving higher-derivative theories of gravity and, more importantly, with fully known gauge-gravity correspondence.
Emori, Satoru; Gray, Benjamin A; Jeon, Hyung-Min; Peoples, Joseph; Schmitt, Maxwell; Mahalingam, Krishnamurthy; Hill, Madelyn; McConney, Michael E; Gray, Matthew T; Alaan, Urusa S; Bornstein, Alexander C; Shafer, Padraic; N'Diaye, Alpha T; Arenholz, Elke; Haugstad, Greg; Meng, Keng-Yuan; Yang, Fengyuan; Li, Dongyao; Mahat, Sushant; Cahill, David G; Dhagat, Pallavi; Jander, Albrecht; Sun, Nian X; Suzuki, Yuri; Howe, Brandon M
2017-09-01
Low-loss magnetization dynamics and strong magnetoelastic coupling are generally mutually exclusive properties due to opposing dependencies on spin-orbit interactions. So far, the lack of low-damping, magnetostrictive ferrite films has hindered the development of power-efficient magnetoelectric and acoustic spintronic devices. Here, magnetically soft epitaxial spinel NiZnAl-ferrite thin films with an unusually low Gilbert damping parameter (ferrite. At the same time, the coherently strained film structure suppresses extrinsic damping, enables soft magnetic behavior, and generates large easy-plane magnetoelastic anisotropy. These findings provide a foundation for a new class of low-loss, magnetoelastic thin film materials that are promising for spin-mechanical devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Directory of Open Access Journals (Sweden)
Yucel Yildirim
2011-09-01
Full Text Available A generic theory of the quasiparticle superconducting gap in underdoped cuprates is derived in the strong-coupling limit, and found to describe the experimental “second gap” in absolute scale. In drastic contrast to the standard pairing gap associated with Bogoliubov quasiparticle excitations, the quasiparticle gap is shown to originate from anomalous kinetic (scattering processes, with a size unrelated to the pairing strength. Consequently, the k dependence of the gap deviates significantly from the pure d_{x^{2}-y^{2}} wave of the order parameter. Our study reveals a new paradigm for the nature of the superconducting gap, and is expected to reconcile numerous apparent contradictions among existing experiments and point toward a more coherent understanding of high-temperature superconductivity.
Observation of dust acoustic shock wave in a strongly coupled dusty plasma
International Nuclear Information System (INIS)
Sharma, Sumita K.; Boruah, A.; Nakamura, Y.; Bailung, H.
2016-01-01
Dust acoustic shock wave is observed in a strongly coupled laboratory dusty plasma. A supersonic flow of charged microparticles is allowed to perturb a stationary dust fluid to excite dust acoustic shock wave. The evolution process beginning with steepening of initial wave front and then formation of a stable shock structure is similar to the numerical results of the Korteweg-de Vries-Burgers equation. The measured Mach number of the observed shock wave agrees with the theoretical results. Reduction of shock amplitude at large distances is also observed due to the dust neutral collision and viscosity effects. The dispersion relation and the spatial damping of a linear dust acoustic wave are also measured and compared with the relevant theory.
Strong Bulk-Edge Coupling in the Compressible Half-Filled Quantum Hall State
International Nuclear Information System (INIS)
Milovanovic, M.V.; Shimshoni, E.
1999-01-01
We studied analytically static correlators in the compressible half-filled quantum Hall state, which characterize the nature of charged excitations in the bulk and on the edge of the system. We employ a modified version of the plasma analogy - namely, a mapping to a classical two-dimensional system of interacting particles - similarly to what has been done in studies of the incompressible (Laughlin) states. However, the 'fake plasma' corresponding to the half-filled state is found to have anomalously weak screening properties. As a consequence, the correlations along the edge do not decay algebraically as in the incompressible case, thus indicating the breakdown of Wen's edge theory. On the other hand, the bulk correlator (which parallels the Girvin-MacDonald algebraic off-diagonal long range order) decays algebraically in a similar way as in the incompressible states, signifying the presence of some kind of bosonic order even in the compressible state. The above results suggest that due to the strong coupling between charged modes on the edge and the neutral Fermions (dipoles) in the bulk, the (attractive) correlation hole is not well defined on the edge. Hence, the system there can be modeled as a free Fermi gas of electrons (with an appropriate boundary condition). A possible experimental indication of a strong bulk-edge coupling at half-filling has been indeed observed in non-local resistance measurements [1]. We also suggest, that while our results contradict the validity of an effective one-dimensional description of the edge excitations on the static level, the dynamics may decouple the edge and bulk so as to recover the Laughlin-like behavior apparent in the experiment of Grayson et al
Liu, Peter Q.; Luxmoore, Isaac J.; Mikhailov, Sergey A.; Savostianova, Nadja A.; Valmorra, Federico; Faist, Jérôme; Nash, Geoffrey R.
2015-01-01
Metamaterials and plasmonics are powerful tools for unconventional manipulation and harnessing of light. Metamaterials can be engineered to possess intriguing properties lacking in natural materials, such as negative refractive index. Plasmonics offers capabilities of confining light in subwavelength dimensions and enhancing light–matter interactions. Recently, the technological potential of graphene-based plasmonics has been recognized as the latter features large tunability, higher field-confinement and lower loss compared with metal-based plasmonics. Here, we introduce hybrid structures comprising graphene plasmonic resonators coupled to conventional split-ring resonators, thus demonstrating a type of highly tunable metamaterial, where the interaction between the two resonances reaches the strong-coupling regime. Such hybrid metamaterials are employed as high-speed THz modulators, exhibiting ∼60% transmission modulation and operating speed in excess of 40 MHz. This device concept also provides a platform for exploring cavity-enhanced light–matter interactions and optical processes in graphene plasmonic structures for applications including sensing, photo-detection and nonlinear frequency generation. PMID:26584781
Radiation by a heavy quark in N=4 SYM at strong coupling
Hatta, Y; Mueller, A H; Triantafyllopoulos, D N
2011-01-01
Using the AdS/CFT correspondence in the supergravity approximation, we compute the energy density radiated by a heavy quark undergoing some arbitrary motion in the vacuum of the strongly coupled N=4 supersymmetric Yang-Mills theory. We find that this energy is fully generated via backreaction from the near-boundary endpoint of the dual string attached to the heavy quark. Because of that, the energy distribution shows the same space-time localization as the classical radiation that would be produced by the heavy quark at weak coupling. We believe that this and some other unnatural features of our result (like its anisotropy and the presence of regions with negative energy density) are artifacts of the supergravity approximation, which will be corrected after including string fluctuations. For the case where the quark trajectory is bounded, we also compute the radiated power, by integrating the energy density over the surface of a sphere at infinity. For sufficiently large times, we find agreement with a previo...
Crossover from weak to strong coupling superconductivity in multi-band systems
Energy Technology Data Exchange (ETDEWEB)
Dinola Neto, Francisco [Instituto de Fisica, Universidade Federal Fluminense, Campus da Praia Vermelha, Niteroi, RJ, 24.210-340 (Brazil); Continentino, Mucio A [Centro Brasileiro de Pesquisas FIsicas, Rua Dr Xavier Sigaud, 150-Urca, Rio de Janeiro, RJ, 22290-180 (Brazil); Lacroix, Claudine, E-mail: claudine.lacroix@grenoble.cnrs.f [Institut Neel, CNRS-UJF, 25 avenue des Martyrs, BP 166, 38042 Grenoble Cedex 9 (France)
2010-02-24
The study of superconductivity in correlated systems is an exciting area of condensed matter physics. In this paper we consider superconducting ground states in systems described by two-band models with different effective masses. These two bands are coupled through an effective hybridization that can be directly tuned by pressure. We consider the cases of s-wave superconductivity associated with the electrons in a narrow band and also with inter-band pairing. To study the system in the strong coupling regime we introduce the s-wave scattering length a{sub s}, and obtain the superconducting order parameters and the chemical potential as functions of the interaction strength 1/k{sub F}a{sub s} along the BCS-BEC crossover at T = 0. Finally, we discuss the phase diagram of this model as a function of external pressure and how our results can be applied for two-band systems as Fe pnictides or heavy fermions. The main result of this study is the occurrence of a superconducting quantum critical point (SQCP) in this two-band model.
Liu, Peter Q.; Luxmoore, Isaac J.; Mikhailov, Sergey A.; Savostianova, Nadja A.; Valmorra, Federico; Faist, Jérôme; Nash, Geoffrey R.
2015-11-01
Metamaterials and plasmonics are powerful tools for unconventional manipulation and harnessing of light. Metamaterials can be engineered to possess intriguing properties lacking in natural materials, such as negative refractive index. Plasmonics offers capabilities of confining light in subwavelength dimensions and enhancing light-matter interactions. Recently, the technological potential of graphene-based plasmonics has been recognized as the latter features large tunability, higher field-confinement and lower loss compared with metal-based plasmonics. Here, we introduce hybrid structures comprising graphene plasmonic resonators coupled to conventional split-ring resonators, thus demonstrating a type of highly tunable metamaterial, where the interaction between the two resonances reaches the strong-coupling regime. Such hybrid metamaterials are employed as high-speed THz modulators, exhibiting ~60% transmission modulation and operating speed in excess of 40 MHz. This device concept also provides a platform for exploring cavity-enhanced light-matter interactions and optical processes in graphene plasmonic structures for applications including sensing, photo-detection and nonlinear frequency generation.
Lasing by driven atoms-cavity system in collective strong coupling regime.
Sawant, Rahul; Rangwala, S A
2017-09-12
The interaction of laser cooled atoms with resonant light is determined by the natural linewidth of the excited state. An optical cavity is another optically resonant system where the loss from the cavity determines the resonant optical response of the system. The near resonant combination of an optical Fabry-Pérot cavity with laser cooled and trapped atoms couples two distinct optical resonators via light and has great potential for precision measurements and the creation of versatile quantum optics systems. Here we show how driven magneto-optically trapped atoms in collective strong coupling regime with the cavity leads to lasing at a frequency red detuned from the atomic transition. Lasing is demonstrated experimentally by the observation of a lasing threshold accompanied by polarization and spatial mode purity, and line-narrowing in the outcoupled light. Spontaneous emission into the cavity mode by the driven atoms stimulates lasing action, which is capable of operating as a continuous wave laser in steady state, without a seed laser. The system is modeled theoretically, and qualitative agreement with experimentally observed lasing is seen. Our result opens up a range of new measurement possibilities with this system.
On the absence of pentaquark states from dynamics in strongly coupled lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Anjos, Petrus Henrique Ribeiro dos [Universidade Federal de Goias (UFG), Goiania, GO (Brazil); Veiga, Paulo Afonso Faria da; O' Carroll, Michael [Universidade de Sao Paulo (USP), SP (Brazil); Francisco Neto, Antonio [Universidade Federal de Ouro Preto (UFOP), MG (Brazil)
2011-07-01
Full text: We consider an imaginary time functional integral formulation of a two-flavor, 3 + 1 lattice QCD model with Wilson's action and in the strong coupling regime (with a small hopping parameter, {kappa}0, and a much smaller plaquette coupling, {beta} = 1/g{sub 0}{sup 2}, so that the quarks and glueballs are heavy). The model has local SU(3){sub c} gauge and global SU(2){sub f} flavor symmetries, and incorporates the corresponding part of the eightfold way particles: baryons (mesons) of asymptotic mass -3ln{kappa}(-2 ln {kappa}). We search for pentaquark states as meson-baryon bound states in the energy-momentum spectrum of the model, using a lattice Bethe-Salpeter equation. This equation is solved within a ladder approximation, given by the lowest nonvanishing order in {kappa} and {beta} of the Bethe-Salpeter kernel. It includes order 2 contributions with a q-barq exchange potential together with a contribution that is a local-in-space, energy-dependent potential. The attractive or repulsive nature of the exchange interaction depends on the spin of the meson-baryon states. The Bethe-Salpeter equation presents integrable singularities, forcing the couplings to be above a threshold value for the meson and the baryon to bind in a pentaquark. We analyzed all the total isospin sectors, I = 1/2/3/2/ 5/2, for the system. For all I, the net attraction resulting from the two sources of interaction is not strong enough for the meson and the baryon to bind. Thus, within our approximation, these pentaquark states are not present up to near the free meson-baryon energy threshold of - 5 ln{kappa}. This result is to be contrasted with the spinless case for which our method detects meson-baryon bound states, as well as for Yukawa effective baryon and meson field models. A physical interpretation of our results emerges from an approximate correspondence between meson-baryon bound states and negative energy states of a one-particle lattice Schroedinger Hamiltonian
Ilgen, Julian; Kaltschnee, Lukas; Thiele, Christina M.
2018-01-01
Motivated by the persisting need for enhanced resolution in solution state NMR spectra, pure shift techniques such as Zangger-Sterk decoupling have recently attracted widespread interest. These techniques for homonuclear decoupling offer enhanced resolution in one- and multidimensional proton detected experiments by simplifying multiplet structures. In this work, a modification to the popular Zangger-Sterk technique PEPSIE (Perfect Echo Pure Shift Improved Experiment) is presented, which decouples pairs of spins even if they share the same volume element. This in turn can drastically improve the sensitivity, as compared to classical Zangger-Sterk decoupling, as larger volume elements can be used to collect the detected signal. Most interestingly, even in the presence of moderate strong coupling, the PEPSIE experiment produces clean and widely artifact free spectra. In order to better understand this - to us initially - surprising behaviour we performed analyses using numerical simulations and derived an (approximate) analytical solution from density matrix formalism. We show that this experiment is particularly suitable to study samples with strong signal clustering, a situation which can render classic Zangger-Sterk decoupling inefficient.
Energy Technology Data Exchange (ETDEWEB)
Acosta, L.; Martel, I.; Perez-Bernal, F.; Rodriguez, D.; Sanchez-Benitez, A.M. [Universidad de Huelva, Departamento de Fisica Aplicada, Huelva (Spain); Alvarez, M.A.G.; Gomez-Camacho, J. [Universidad de Sevilla, Departamento de Fisica Atomica Molecular y Nuclear, Sevilla (Spain); Universidad de Sevilla-CSIC-Junta de Andalucia, Centro Nacional de Aceleradores, Sevilla (Spain); Andres, M.V.; Espino, J.M.; Moro, A.M.; Mukha, I. [Universidad de Sevilla, Departamento de Fisica Atomica Molecular y Nuclear, Sevilla (Spain); Borge, M.J.G.; Cortes, M.; Galaviz, D.; Maira, A.; Reillo, E.; Tengblad, O. [CSIC, Madrid, Instituto de Estructura de la Materia, Madrid (Spain); Rusek, K. [The Andrzej Soltan Institute for Nuclear Studies, Warsaw (Poland)
2009-12-15
The angular distribution for {sup 11}Be+{sup 120}Sn quasielastic scattering at E{sub lab}=32 MeV was measured at REX-ISOLDE, CERN. The interpretation of the data in terms of coupled-channel calculations suggests a strong coupling with the p-states lying in the continuum. (orig.)
The strongly coupled fourth family and a first-order electroweak phase transition. 1. Quark sector
International Nuclear Information System (INIS)
Kikukawa, Yoshio; Kohda, Masaya; Yasuda, Junichiro
2009-01-01
In models of dynamical electroweak symmetry breaking due to strongly coupled fourth-family quarks and leptons, their low-energy effective descriptions may involve multiple composite Higgs fields, leading to a possibility that the electroweak phase transition at finite temperature is first-order due to the Coleman-Weinberg mechanism. We examine the behavior of the electroweak phase transition on the basis of the effective renormalizable Yukawa theory, which consists of the fourth-family quarks and two SU(2)-doublet Higgs fields corresponding to the bilinear operators of the fourth-family quarks with/without imposing the compositeness condition. The strength of the first-order phase transition is estimated using the finite-temperature effective potential at one loop with ring improvement. In the Yukawa theory without the compositeness condition, it is found that there is a parameter region where the first-order phase transition is sufficiently strong for the electroweak baryogenesis with the experimentally acceptable Higgs boson and fourth-family quark masses. On the other hand, when the compositeness condition is imposed, the phase transition turns out to be weakly first-order, or possibly second-order, although the result is rather sensitive to the details of the compositeness condition. By combining with the result of the Yukawa theory without the compositeness condition, it is argued that with the fourth-family quark masses in the range of 330-480 GeV, corresponding to the compositeness scale in the range of 1.0-2.3 TeV, the four-fermion interaction among the fourth-family quarks does not lead to the strongly first-order electroweak phase transition. (author)
International Nuclear Information System (INIS)
Faucher, V.
2014-01-01
This HDR is dedicated to the research in the framework of fast transient dynamics for industrial fluid-structure systems carried in the Laboratory of Dynamic Studies from CEA, implementing new numerical methods for the modelling of complex systems and the parallel solution of large coupled problems on supercomputers. One key issue for the proposed approaches is the limitation to its minimum of the number of non-physical parameters, to cope with constraints arising from the area of usage of the concepts: safety for both nuclear applications (CEA, EDF) and aeronautics (ONERA), protection of the citizen (EC/JRC) in particular. Kinematic constraints strongly coupling structures (namely through unilateral contact) or fluid and structures (with both conformant or non-conformant meshes depending on the geometrical situation) are handled through exact methods including Lagrange Multipliers, with consequences on the solution strategy to be dealt with. This latter aspect makes EPX, the simulation code where the methods are integrated, a singular tool in the community of fast transient dynamics software. The document mainly relies on a description of the modelling needs for industrial fast transient scenarios, for nuclear applications in particular, and the proposed solutions built in the framework of the collaboration between CEA, EDF (via the LaMSID laboratory) and the LaMCoS laboratory from INSA Lyon. The main considered examples are the tearing of the fluid-filled tank after impact, the Code Disruptive Accident for a Generation IV reactor or the ruin of reinforced concrete structures under impact. Innovative models and parallel algorithms are thus proposed, allowing to carry out with robustness and performance the corresponding simulations on supercomputers made of interconnected multi-core nodes, with a strict preservation of the quality of the physical solution. This was particularly the main point of the ANR RePDyn project (2010-2013), with CEA as the pilot. (author
Inert two-Higgs-doublet model strongly coupled to a non-Abelian vector resonance
Rojas-Abatte, Felipe; Mora, Maria Luisa; Urbina, Jose; Zerwekh, Alfonso R.
2017-11-01
We study the possibility of a dark matter candidate having its origin in an extended Higgs sector which, at least partially, is related to a new strongly interacting sector. More concretely, we consider an i2HDM (i.e., a Type-I two Higgs doublet model supplemented with a Z2 under which the nonstandard scalar doublet is odd) based on the gauge group S U (2 )1×S U (2 )2×U (1 )Y . We assume that one of the scalar doublets and the standard fermion transform nontrivially under S U (2 )1 while the second doublet transforms under S U (2 )2. Our main hypothesis is that standard sector is weakly coupled while the gauge interactions associated to the second group is characterized by a large coupling constant. We explore the consequences of this construction for the phenomenology of the dark matter candidate and we show that the presence of the new vector resonance reduces the relic density saturation region, compared to the usual i2DHM, in the high dark matter mass range. In the collider side, we argue that the mono-Z production is the channel which offers the best chances to manifest the presence of the new vector field. We study the departures from the usual i2HDM predictions and show that the discovery of the heavy vector at the LHC is challenging even in the mono-Z channel since the typical cross sections are of the order of 10-2 fb .
Angular structure of jet quenching within a hybrid strong/weak coupling model
Energy Technology Data Exchange (ETDEWEB)
Casalderrey-Solana, Jorge [Rudolf Peierls Centre for Theoretical Physics, University of Oxford,1 Keble Road, Oxford OX1 3NP (United Kingdom); Departament de Física Quàntica i Astrofísica & Institut de Ciències del Cosmos (ICC),Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona (Spain); Gulhan, Doga Can [CERN, EP Department,CH-1211 Geneva 23 (Switzerland); Milhano, José Guilherme [CENTRA, Instituto Superior Técnico, Universidade de Lisboa,Av. Rovisco Pais, P-1049-001 Lisboa (Portugal); Laboratório de Instrumentação e Física Experimental de Partículas (LIP),Av. Elias Garcia 14-1, P-1000-149 Lisboa (Portugal); Theoretical Physics Department, CERN,Geneva (Switzerland); Pablos, Daniel [Departament de Física Quàntica i Astrofísica & Institut de Ciències del Cosmos (ICC),Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona (Spain); Rajagopal, Krishna [Center for Theoretical Physics, Massachusetts Institute of Technology,Cambridge, MA 02139 (United States)
2017-03-27
Within the context of a hybrid strong/weak coupling model of jet quenching, we study the modification of the angular distribution of the energy within jets in heavy ion collisions, as partons within jet showers lose energy and get kicked as they traverse the strongly coupled plasma produced in the collision. To describe the dynamics transverse to the jet axis, we add the effects of transverse momentum broadening into our hybrid construction, introducing a parameter K≡q̂/T{sup 3} that governs its magnitude. We show that, because of the quenching of the energy of partons within a jet, even when K≠0 the jets that survive with some specified energy in the final state are narrower than jets with that energy in proton-proton collisions. For this reason, many standard observables are rather insensitive to K. We propose a new differential jet shape ratio observable in which the effects of transverse momentum broadening are apparent. We also analyze the response of the medium to the passage of the jet through it, noting that the momentum lost by the jet appears as the momentum of a wake in the medium. After freezeout this wake becomes soft particles with a broad angular distribution but with net momentum in the jet direction, meaning that the wake contributes to what is reconstructed as a jet. This effect must therefore be included in any description of the angular structure of the soft component of a jet. We show that the particles coming from the response of the medium to the momentum and energy deposited in it leads to a correlation between the momentum of soft particles well separated from the jet in angle with the direction of the jet momentum, and find qualitative but not quantitative agreement with experimental data on observables designed to extract such a correlation. More generally, by confronting the results that we obtain upon introducing transverse momentum broadening and the response of the medium to the jet with available jet data, we highlight the
Wu, Ning; Feist, Johannes; Garcia-Vidal, Francisco J.
2016-11-01
We present a microscopic semianalytical theory for the description of organic molecules interacting strongly with a cavity mode. Exciton-vibration coupling within the molecule and exciton-cavity interaction are treated on an equal footing by employing a temperature-dependent variational approach. The interplay between strong exciton-vibration coupling and strong exciton-cavity coupling gives rise to a hybrid ground state, which we refer to as the lower polaron polariton. Explicit expressions for the ground-state wave function, the zero-temperature quasiparticle weight of the lower polaron polariton, the photoluminescence line strength, and the mean number of vibrational quanta are obtained in terms of the optimal variational parameters. The dependence of these quantities upon the exciton-cavity coupling strength reveals that strong cavity coupling leads to an enhanced vibrational dressing of the cavity mode, and at the same time a vibrational decoupling of the dark excitons, which in turn results in a lower polaron polariton resembling a single-mode dressed bare lower polariton in the strong-coupling regime. Thermal effects on several observables are briefly discussed.
Strongly coupled interaction between a ridge of fluid and an inviscid airflow
Paterson, C.
2015-07-01
© 2015 AIP Publishing LLC. The behaviour of a steady thin sessile or pendent ridge of fluid on an inclined planar substrate which is strongly coupled to the external pressure gradient arising from an inviscid airflow parallel to the substrate far from the ridge is described. When the substrate is nearly horizontal, a very wide ridge can be supported against gravity by capillary and/or external pressure forces; otherwise, only a narrower (but still wide) ridge can be supported. Classical thin-aerofoil theory is adapted to obtain the governing singular integro-differential equation for the profile of the ridge in each case. Attention is focused mainly on the case of a very wide sessile ridge. The effect of strengthening the airflow is to push a pinned ridge down near to its edges and to pull it up near to its middle. At a critical airflow strength, the upslope contact angle reaches the receding contact angle at which the upslope contact line de-pins, and continuing to increase the airflow strength beyond this critical value results in the de-pinned ridge becoming narrower, thicker, and closer to being symmetric in the limit of a strong airflow. The effect of tilting the substrate is to skew a pinned ridge in the downslope direction. Depending on the values of the advancing and receding contact angles, the ridge may first de-pin at either the upslope or the downslope contact line but, in general, eventually both contact lines de-pin. The special cases in which only one of the contact lines de-pins are also considered. It is also shown that the behaviour of a very wide pendent ridge is qualitatively similar to that of a very wide sessile ridge, while the important qualitative difference between the behaviour of a very wide ridge and a narrower ridge is that, in general, for the latter one or both of the contact lines may never de-pin.
Delord, T.; Nicolas, L.; Chassagneux, Y.; Hétet, G.
2017-12-01
A scheme for strong coupling between a single atomic spin and the rotational mode of levitating nanoparticles is proposed. The idea is based on spin readout of nitrogen-vacancy centers embedded in aspherical nanodiamonds levitating in an ion trap. We show that the asymmetry of the diamond induces a rotational confinement in the ion trap. Using a weak homogeneous magnetic field and a strong microwave driving we then demonstrate that the spin of the nitrogen-vacancy center can be strongly coupled to the rotational mode of the diamond.
On the evolution of jet energy and opening angle in strongly coupled plasma
International Nuclear Information System (INIS)
Chesler, Paul M.; Rajagopal, Krishna
2016-01-01
We calculate how the energy and the opening angle of jets in N=4 SYM theory evolve as they propagate through the strongly coupled plasma of that theory. We define the rate of energy loss dE jet /dx and the jet opening angle in a straightforward fashion directly in the gauge theory before calculating both holographically, in the dual gravitational description. In this way, we rederive the previously known result for dE jet /dx without the need to introduce a finite slab of plasma. We obtain a striking relationship between the initial opening angle of the jet, which is to say the opening angle that it would have had if it had found itself in vacuum instead of in plasma, and the thermalization distance of the jet. Via this relationship, we show that N=4 SYM jets with any initial energy that have the same initial opening angle and the same trajectory through the plasma experience the same fractional energy loss. We also provide an expansion that describes how the opening angle of the N=4 SYM jets increases slowly as they lose energy, over the fraction of their lifetime when their fractional energy loss is not yet large. We close by looking ahead toward potential qualitative lessons from our results for QCD jets produced in heavy collisions and propagating through quark-gluon plasma.
Precision determination of the strong coupling constant within a global PDF analysis arXiv
Ball, Richard D.; Del Debbio, Luigi; Forte, Stefano; Kassabov, Zahari; Rojo, Juan; Slade, Emma; Ubiali, Maria
We present a determination of the strong coupling constant $\\alpha_s(m_Z)$ based on the NNPDF3.1 determination of parton distributions, which for the first time includes constraints from jet production, top-quark pair differential distributions, and the $Z$ $p_T$ distributions using exact NNLO theory. Our result is based on a novel extension of the NNPDF methodology - the correlated replica method - which allows for a simultaneous determination of $\\alpha_s$ and the PDFs with all correlations between them fully taken into account. We study in detail all relevant sources of experimental, methodological and theoretical uncertainty. At NNLO we find $\\alpha_s(m_Z) = 0.1185 \\pm 0.0005^\\text{(exp)}\\pm 0.0001^\\text{(meth)}$, showing that methodological uncertainties are negligible. We conservatively estimate the theoretical uncertainty due to missing higher order QCD corrections (N$^3$LO and beyond) from half the shift between the NLO and NNLO $\\alpha_s$ values, finding $\\Delta\\alpha^{\\rm th}_s =0.0011$.
Confined surface plasmon sensors based on strongly coupled disk-in-volcano arrays.
Ai, Bin; Wang, Limin; Möhwald, Helmuth; Yu, Ye; Zhang, Gang
2015-02-14
Disk-in-volcano arrays are reported to greatly enhance the sensing performance due to strong coupling in the nanogaps between the nanovolcanos and nanodisks. The designed structure, which is composed of a nanovolcano array film and a disk in each cavity, is fabricated by a simple and efficient colloidal lithography method. By tuning structural parameters, the disk-in-volcano arrays show greatly enhanced resonances in the nanogaps formed by the disks and the inner wall of the volcanos. Therefore they respond to the surrounding environment with a sensitivity as high as 977 nm per RIU and with excellent linear dependence on the refraction index. Moreover, through mastering the fabrication process, biological sensing can be easily confined to the cavities of the nanovolcanos. The local responsivity has the advantages of maximum surface plasmon energy density in the nanogaps, reducing the sensing background and saving expensive reagents. The disk-in-volcano arrays also possess great potential in applications of optical and electrical trapping and single-molecule analysis, because they enable establishment of electric fields across the gaps.
Measurement of jet production with the ATLAS detector and extraction of the strong coupling constant
Sawyer, Lee; The ATLAS collaboration
2017-01-01
The production of jets at hadron colliders provides a stringent test of perturbative QCD at the highest energies. The process can also be used to probe the gluon density function of the proton. Specific topologies can be used to extract the strong coupling constant. The ATLAS collaboration has recently measured the inclusive jet production cross section in data collected at a center-of-mass energy of 8TeV and 13TeV. The measurements have been performed differentially in jet rapidity and transverse momentum. The collaboration also presents a first measurement of the di-jet cross section at a center-of-mass energy of 13TeV as a function of the di-jet mass and rapidity. The results have been compared with state-of-the-art theory predictions at NLO in pQCD, interfaced with different parton distribution functions and can be used to constrain the proton structure. We also present new measurements of transverse energy-energy correlations (TEEC) and their associated asymmetries (ATEEC) in multi-jet events at a center...
Mamo, Kiminad A.
2012-10-01
We study holographic RG flow of the shear viscosity tensor of anisotropic, strongly coupled {N}=4 super-Yang-Mills plasma by using its type IIB supergravity dual in anisotropic bulk spacetime. We find that the shear viscosity tensor has three independent components in the anisotropic bulk spacetime away from the boundary, and one of the components has a non-trivial RG flow while the other two have a trivial one. For the component of the shear viscosity tensor with non-trivial RG flow, we derive its RG flow equation, and solve the equation analytically to second order in the anisotropy parameter a. We derive the RG equation using the equation of motion, holographic Wilsonian RG method, and Kubo's formula. All methods give the same result. Solving the equation, we find that the ratio of the component of the shear viscosity tensor to entropy density η /s flows from above 1/{4π } the horizon (IR) to below 1/{4π } the boundary (UV) where it violates the holographic shear viscosity (Kovtun-Son-Starinets) bound and where it agrees with the other longitudinal component.
Wang, Hao; Cao, Yingjie; Sun, Cheng; Zou, Guifu; Huang, Jianwen; Kuai, Xiaoxiao; Zhao, Jianqing; Gao, Lijun
2017-09-22
High-performance and affordable electrocatalysts from earth-abundant elements are desirably pursued for water splitting involving hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Here, a bifunctional electrocatalyst of highly crystalline Mo 2 C nanoparticles supported on carbon sheets (Mo 2 C/CS) was designed toward overall water splitting. Owing to the highly active catalytic nature of Mo 2 C nanoparticles, the high surface area of carbon sheets and efficient charge transfer in the strongly coupled composite, the designed catalysts show excellent bifunctional behavior with an onset potential of -60 mV for HER and an overpotential of 320 mV to achieve a current density of 10 mA cm -2 for OER in 1 m KOH while maintaining robust stability. Moreover, the electrolysis cell using the catalyst only requires a low cell voltage of 1.73 V to achieve a current density of 10 mA cm -2 and maintains the activity for more than 100 h when employing the Mo 2 C/CS catalyst as both anode and cathode electrodes. Such high performance makes Mo 2 C/CS a promising electrocatalyst for practical hydrogen production from water splitting. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Engineering light emission of two-dimensional materials in both the weak and strong coupling regimes
Brotons-Gisbert, Mauro; Martínez-Pastor, Juan P.; Ballesteros, Guillem C.; Gerardot, Brian D.; Sánchez-Royo, Juan F.
2018-01-01
Two-dimensional (2D) materials have promising applications in optoelectronics, photonics, and quantum technologies. However, their intrinsically low light absorption limits their performance, and potential devices must be accurately engineered for optimal operation. Here, we apply a transfer matrix-based source-term method to optimize light absorption and emission in 2D materials and related devices in weak and strong coupling regimes. The implemented analytical model accurately accounts for experimental results reported for representative 2D materials such as graphene and MoS2. The model has been extended to propose structures to optimize light emission by exciton recombination in MoS2 single layers, light extraction from arbitrarily oriented dipole monolayers, and single-photon emission in 2D materials. Also, it has been successfully applied to retrieve exciton-cavity interaction parameters from MoS2 microcavity experiments. The present model appears as a powerful and versatile tool for the design of new optoelectronic devices based on 2D semiconductors such as quantum light sources and polariton lasers.
The ATLAS Measurements of Jet Production and the Strong Coupling Constant
Sawyer, Lee; The ATLAS collaboration
2017-01-01
The production of jets at hadron colliders provides a stringent test of perturbative QCD at the highest energies. The process can also be used to probe the gluon density in the parton distribution function of the proton. Specific topologies can be used to extract the strong coupling constant. The ATLAS collaboration has recently measured the inclusive jet production cross section in data collected at a center-of-mass energy of 8 TeV and 13 TeV. The measurements have been performed differentially in jet rapidity and transverse momentum. The collaboration also presents a first measurement of the dijet cross section at a center-of-mass energy of 13 TeV as a function of the dijet invariant mass and rapidity. The results have been compared with state-of-the-art theory predictions at NLO in pQCD, interfaced with different parton distribution functions and can be used to constrain the proton structure. We also present new measurements of transverse energy-energy correlations (TEEC) and their associated asymmetries (...
Heavy flavor at the large hadron collider in a strong coupling approach
Energy Technology Data Exchange (ETDEWEB)
He, Min [Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094 (China); Fries, Rainer J.; Rapp, Ralf [Cyclotron Institute and Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843-3366 (United States)
2014-07-30
Employing nonperturbative transport coefficients for heavy-flavor (HF) diffusion through quark–gluon plasma (QGP), hadronization and hadronic matter, we compute D- and B-meson observables in Pb+Pb (√(s)=2.76 TeV) collisions at the LHC. Elastic heavy-quark scattering in the QGP is evaluated within a thermodynamic T-matrix approach, generating resonances close to the critical temperature which are utilized for recombination into D and B mesons, followed by hadronic diffusion using effective hadronic scattering amplitudes. The transport coefficients are implemented via Fokker–Planck Langevin dynamics within hydrodynamic simulations of the bulk medium in nuclear collisions. The hydro expansion is quantitatively constrained by transverse-momentum spectra and elliptic flow of light hadrons. Our approach thus incorporates the paradigm of a strongly coupled medium in both bulk and HF dynamics throughout the thermal evolution of the system. At low and intermediate p{sub T}, HF observables at LHC are reasonably well accounted for, while discrepancies at high p{sub T} are indicative for radiative mechanisms not included in our approach.
International Nuclear Information System (INIS)
Decker, K.; Hamburg Univ.
1985-12-01
An efficient description of all clusters contributing to the strong coupling expansion of the mass gap in three-dimensional pure Z 2 lattice gauge theory is presented. This description is correct to all orders in the strong coupling expansion and is chosen in such a way that it remains valid in four dimensions for gauge group Z 2 . Relying on this description an algorithm has been constructed which generates and processes all the contributing graphs to the exact strong coupling expansion of the mass gap in the three-dimensional model in a fully automatic fashion. A major component of this algorithm can also be used to generate exact strong coupling expansions for the free energy logZ. The algorithm is correct to any order; thus the order of these expansions is only limited by the available computing power. The presentation of the algorithm is such that it can serve as a guide-line for the construction of a generalized one which would also generate exact strong coupling expansions for the masses of low-lying excited states of four-dimensional pure Yang-Mills theories. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Zhao, Haihua [Idaho National Laboratory; Zhang, Hongbin [Idaho National Laboratory; Zou, Ling [Idaho National Laboratory; Martineau, Richard Charles [Idaho National Laboratory
2015-03-01
The reactor core isolation cooling (RCIC) system in a boiling water reactor (BWR) provides makeup cooling water to the reactor pressure vessel (RPV) when the main steam lines are isolated and the normal supply of water to the reactor vessel is lost. The RCIC system operates independently of AC power, service air, or external cooling water systems. The only required external energy source is from the battery to maintain the logic circuits to control the opening and/or closure of valves in the RCIC systems in order to control the RPV water level by shutting down the RCIC pump to avoid overfilling the RPV and flooding the steam line to the RCIC turbine. It is generally considered in almost all the existing station black-out accidents (SBO) analyses that loss of the DC power would result in overfilling the steam line and allowing liquid water to flow into the RCIC turbine, where it is assumed that the turbine would then be disabled. This behavior, however, was not observed in the Fukushima Daiichi accidents, where the Unit 2 RCIC functioned without DC power for nearly three days. Therefore, more detailed mechanistic models for RCIC system components are needed to understand the extended SBO for BWRs. As part of the effort to develop the next generation reactor system safety analysis code RELAP-7, we have developed a strongly coupled RCIC system model, which consists of a turbine model, a pump model, a check valve model, a wet well model, and their coupling models. Unlike the traditional SBO simulations where mass flow rates are typically given in the input file through time dependent functions, the real mass flow rates through the turbine and the pump loops in our model are dynamically calculated according to conservation laws and turbine/pump operation curves. A simplified SBO demonstration RELAP-7 model with this RCIC model has been successfully developed. The demonstration model includes the major components for the primary system of a BWR, as well as the safety
Curious Consequences of Strong Coupling in NMR Experiments Involving Selective Pulses
Huth, Johannes; Fu, Riqiang; Bodenhausen, Geoffrey
This study is concerned with the effects of applying selective pulses to systems with strong second-order scalar couplings in isotropic phase, where different transitions ( rs) are associated with different transition matrix elements F+( rs) . Two unusual features can be distinguished: the nutation angle ("flip angle") depends on the matrix element of the irradiated transition ( rs), and, in contrast to the behavior of an isolated spin- {1}/{2} system, the norm of the three single-transition operators [ I( rs) x, I( rs) y, I( rs) z] associated with the fictitious spin- {1}/{2} space of the irradiated transition ( rs) is generally not conserved. It is necessary to consider the single-transition operators [ I( rp) x, I( rp) y, I( rp) z] and [ I( sq) x, I( sq) y, I( sq) z] associated with all connected transitions ( rp) and ( sq) that share a common energy level ror swith the irradiated transition ( rs). If the pulse applied to the ( rs) transition is sufficiently selective, the transverse components I( rp) x, I( rp) y, I( sq) x, and I( sq) y, can be neglected, since their expectation values remain equal to zero after application of a selective pulse to the ( rs) transition, but the longitudinal components I( rp) zand I( sq) zacquire nonvanishing expectation values. When the selective pulse affects several transitions simultaneously, the response varies from one transition to another, depending on the matrix elements and the connectivities. These effects manifest themselves in unusual amplitudes and phases of signals excited by selective pulses, in particular in selective two-dimensional correlation spectra.
Electronic transport through a quantum dot chain with strong dot-lead coupling
International Nuclear Information System (INIS)
Liu, Yu; Zheng, Yisong; Gong, Weijiang; Gao, Wenzhu; Lue, Tianquan
2007-01-01
By means of the non-equilibrium Green function technique, the electronic transport through an N-quantum-dot chain is theoretically studied. By calculating the linear conductance spectrum and the local density of states in quantum dots, we find the resonant peaks in the spectra coincides with the eigen-energies of the N-quantum-dot chain when the dot-lead coupling is relatively weak. With the increase of the dot-lead coupling, such a correspondence becomes inaccurate. When the dot-lead coupling exceeds twice the interdot coupling, such a mapping collapses completely. The linear conductance turn to reflect the eigen-energies of the (N-2)- or (N-1)-quantum dot chain instead. The two peripheral quantum dots do not manifest themselves in the linear conductance spectrum. More interestingly, with the further increase of the dot-lead coupling, the system behaves just like an (N-2)- or (N-1)-quantum dot chain in weak dot-lead coupling limit, since the resonant peaks becomes narrower with the increase of dot-lead coupling
Determinations of the QCD strong coupling αsub(s) and the scale Λsub(QCD)
International Nuclear Information System (INIS)
Duke, D.W.; Roberts, R.G.
1984-08-01
The authors review determinations, via experiment of the strong coupling of QCD, αsub(s). In almost every case, the results are used of perturbative QCD to make the necessary extraction from data. These include scaling violations of deep inelastic scattering, e + e - annihilation experiments (including quarkonium decays) and lepton pair production. Finally estimates for Λ from lattice calculations are listed. (author)
DEFF Research Database (Denmark)
Van Vlack, C.; Kristensen, Philip Trøst; Hughes, S.
2012-01-01
the dot to the detector, we demonstrate that the strong-coupling regime should be observable in the far-field spontaneous emission spectrum, even at room temperature. The vacuum-induced emission spectra show that the usual vacuum Rabi doublet becomes a rich spectral triplet or quartet with two of the four...
Energy Technology Data Exchange (ETDEWEB)
Casalderrey-Solana, Jorge [Departament d' Estructura i Constituents de la Matèria and Institut de Ciències del Cosmos (ICCUB), Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona (Spain); Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP (United Kingdom); Gulhan, Doga Can [Laboratory for Nuclear Science and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Milhano, José Guilherme [CENTRA, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, P-1049-001 Lisboa (Portugal); Physics Department, Theory Unit, CERN, CH-1211 Genève 23 (Switzerland); Pablos, Daniel [Departament d' Estructura i Constituents de la Matèria and Institut de Ciències del Cosmos (ICCUB), Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona (Spain); Rajagopal, Krishna [Laboratory for Nuclear Science and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)
2016-12-15
Within a hybrid strong/weak coupling model for jets in strongly coupled plasma, we explore jet modifications in ultra-relativistic heavy ion collisions. Our approach merges the perturbative dynamics of hard jet evolution with the strongly coupled dynamics which dominates the soft exchanges between the fast partons in the jet shower and the strongly coupled plasma itself. We implement this approach in a Monte Carlo, which supplements the DGLAP shower with the energy loss dynamics as dictated by holographic computations, up to a single free parameter that we fit to data. We then augment the model by incorporating the transverse momentum picked up by each parton in the shower as it propagates through the medium, at the expense of adding a second free parameter. We use this model to discuss the influence of the transverse broadening of the partons in a jet on intra-jet observables. In addition, we explore the sensitivity of such observables to the back-reaction of the plasma to the passage of the jet.
Chen, Gengyan; Liu, Jing-Feng; Jiang, Haoxiang; Zhuo, Xiao-Lu; Yu, Yi-Cong; Jin, Chongjun; Wang, Xue-Hua
2013-04-23
The quality factor and mode volume of a nanocavity play pivotal roles in realizing the strong coupling interaction between the nanocavity mode and a quantum dot. We present an extremely simple method to obtain the mode volume and investigate the effect of the slab thickness on the quality factor and mode volume of photonic crystal slab nanocavities. We reveal that the mode volume is approximatively proportional to the slab thickness. As compared with the previous structure finely optimized by introducing displacement of the air holes, via tuning the slab thickness, the quality factor can be enhanced by about 22%, and the ratio between the coupling coefficient and the nanocavity decay rate can be enhanced by about 13%. This can remarkably enhance the capability of the photonic crystal slab nanocavity for realizing the strong coupling interaction. The slab thickness tuning approach is feasible and significant for the experimental fabrication of the solid-state nanocavities.
Energy Technology Data Exchange (ETDEWEB)
Golden, Kenneth I.
2002-09-16
The main research accomplishments/findings of the project were the following: (1) Publication of an in-depth review article in Physics of Plasmas on the quasilocalized charge approximation (QLCA) in strongly coupled plasma physics and its application to a variety of Coulomb systems: the model one-component plasma in three and two dimensions, binary ionic mixtures, charged particle bilayers, and laboratory dusty plasmas. (2) In the strongly coupled Coulomb liquid phase, the physical basis of the QLCA, namely, the caging of particles trapped in slowly fluctuating local potential minima, is supported by molecular dynamics simulation of the classical three-dimensional one-component plasma. (3) The QLCA theory, when applied to the analysis of the collective modes in strongly coupled charged particle bilayers, predicts the existence of a remarkable long-wavelength energy gap in the out-of-phase excitation spectrum. More recent theoretical calculations based on the three principal frequency-moment sum rules reveal that the gap persists for arbitrary coupling strengths and over the entire classical to quantum domain all the way down to zero temperature. The existence of the energy gap has now been confirmed in a molecular dynamics simulation of the charged particle bilayer. (4) New compressibility and third-frequency-moment sum rules for multilayer plasmas were formulated and applied to the analysis of the dynamical structure function of charged particle bilayers and superlattices. (5) An equivalent of the Debye-Huckel weak coupling equilibrium theory for classical charged particle bilayer and superlattice plasmas was formulated. (6) The quadratic fluctuation-dissipation theorem (QFDT) for layered classical plasmas was formulated. (7) The QFDT was applied to a powerful kinetic theory-based description of the density-density response function and long-wavelength plasma mode behavior in strongly coupled two-dimensional Coulomb fluids in the weakly degenerate quantum domain.
Energy Technology Data Exchange (ETDEWEB)
Kang, Hyung-sun; Koh, Young Ha; Jin, Jae Sik [Chosun College of Science and Technology, Gwangju (Korea, Republic of)
2017-06-15
The aim of this study is to understand the phonon transfer characteristics of a silicon thin film transistor. For this purpose, the Joule heating mechanism was considered through the electron-phonon interaction model whose validation has been done. The phonon transport characteristics were investigated in terms of phonon mean free path for the variations in the device power and silicon layer thickness from 41 nm to 177 nm. The results may be used for developing the thermal design strategy for achieving reliability and efficiency of the silicon-on-insulator (SOI) transistor, further, they will increase the understanding of heat conduction in SOI systems, which are very important in the semiconductor industry and the nano-fabrication technology.
Two-qubit gate operations in superconducting circuits with strong coupling and weak anharmonicity
International Nuclear Information System (INIS)
Lü Xinyou; Ashhab, S; Cui Wei; Wu Rebing; Nori, Franco
2012-01-01
We theoretically study the implementation of two-qubit gates in a system of two coupled superconducting qubits. In particular, we analyze two-qubit gate operations under the condition that the coupling strength is comparable with or even larger than the anharmonicity of the qubits. By numerically solving the time-dependent Schrödinger equation under the assumption of negligible decoherence, we obtain the dependence of the two-qubit gate fidelity on the system parameters in the case of both direct and indirect qubit-qubit coupling. Our numerical results can be used to identify the ‘safe’ parameter regime for experimentally implementing two-qubit gates with high fidelity in these systems. (paper)
Strain-Induced Enhancement of the Electron Energy Relaxation in Strongly Correlated Superconductors
Directory of Open Access Journals (Sweden)
C. Gadermaier
2014-03-01
Full Text Available We use femtosecond optical spectroscopy to systematically measure the primary energy relaxation rate Γ_{1} of photoexcited carriers in cuprate and pnictide superconductors. We find that Γ_{1} increases monotonically with increased negative strain in the crystallographic a axis. Generally, the Bardeen-Shockley deformation potential theorem and, specifically, pressure-induced Raman shifts reported in the literature suggest that increased negative strain enhances electron-phonon coupling, which implies that the observed direct correspondence between a and Γ_{1} is consistent with the canonical assignment of Γ_{1} to the electron-phonon interaction. The well-known nonmonotonic dependence of the superconducting critical temperature T_{c} on the a-axis strain is also reflected in a systematic dependence T_{c} on Γ_{1}, with a distinct maximum at intermediate values (∼16 ps^{−1} at room temperature. The empirical nonmonotonic systematic variation of T_{c} with the strength of the electron-phonon interaction provides us with unique insight into the role of electron-phonon interaction in relation to the mechanism of high-T_{c} superconductivity as a crossover phenomenon.
Strong climate coupling of terrestrial and marine environments in the Miocene of northwest Europe
Donders, T.H.; Weijers, J.W.H.; Munsterman, D.K.; Kloosterboer-van Hoeve, M.L.; Buckles, L.K.; Pancost, R.D.; Schouten, S.; Sinninghe Damsté, J.S.; Brinkhuis, H.
2009-01-01
A palynological and organic geochemical record from a shallow marine paleoenvironmental setting in SE Netherlands documents the coupled marine and terrestrial climate evolution from the late Burdigalian (∼ 17 Ma) through the early Zanclean (∼ 4.5 Ma). Proxy climate records show several coeval
Electrical control of spontaneous emission and strong coupling for a single quantum dot
DEFF Research Database (Denmark)
Laucht, A.; Hofbauer, F.; Hauke, N.
2009-01-01
coupling regime, and electrical control of zerodimensional polaritons is demonstrated for the highest-Q cavities (Q > 12 000). Vacuum Rabi splittings up to 120μeV are observed, larger than the linewidths of either the decoupled exciton ( 6 40μeV) or cavity mode. These observations represent a voltage...
Zhang, Yu-Yu; Chen, Xiang-You
2017-12-01
An unexplored nonperturbative deep strong coupling (npDSC) achieved in superconducting circuits has been studied in the anisotropic Rabi model by the generalized squeezing rotating-wave approximation. Energy levels are evaluated analytically from the reformulated Hamiltonian and agree well with numerical ones in a wide range of coupling strength. Such improvement ascribes to deformation effects in the displaced-squeezed state presented by the squeezed momentum variance, which are omitted in previous displaced states. The atom population dynamics confirms the validity of our approach for the npDSC strength. Our approach offers the possibility to explore interesting phenomena analytically in the npDSC regime in qubit-oscillator experiments.
Strong Linear Dichroism in Spin-Polarized Photoemission from Spin-Orbit-Coupled Surface States.
Bentmann, H; Maaß, H; Krasovskii, E E; Peixoto, T R F; Seibel, C; Leandersson, M; Balasubramanian, T; Reinert, F
2017-09-08
A comprehensive understanding of spin-polarized photoemission is crucial for accessing the electronic structure of spin-orbit coupled materials. Yet, the impact of the final state in the photoemission process on the photoelectron spin has been difficult to assess in these systems. We present experiments for the spin-orbit split states in a Bi-Ag surface alloy showing that the alteration of the final state with energy may cause a complete reversal of the photoelectron spin polarization. We explain the effect on the basis of ab initio one-step photoemission theory and describe how it originates from linear dichroism in the angular distribution of photoelectrons. Our analysis shows that the modulated photoelectron spin polarization reflects the intrinsic spin density of the surface state being sampled differently depending on the final state, and it indicates linear dichroism as a natural probe of spin-orbit coupling at surfaces.
The strong running coupling from an approximate gluon Dyson-Schwinger equation
International Nuclear Information System (INIS)
Alkofer, R.; Hauck, A.
1996-01-01
Using Mandelstam's approximation to the gluon Dyson-Schwinger equation we calculate the gluon self-energy in a renormalisation group invariant fashion. We obtain a non-perturbative Β function. The scaling behavior near the ultraviolet stable fixed point is in good agreement with perturbative QCD. No further fixed point for positive values of the coupling is found: α S increases without bound in the infrared
Energy Technology Data Exchange (ETDEWEB)
Kononov, A.; Egorov, S. V. [Russian Academy Sciences, Institute of Solid State Physics (Russian Federation); Kvon, Z. D.; Mikhailov, N. N.; Dvoretsky, S. A. [Institute of Semiconductor Physics (Russian Federation); Deviatov, E. V., E-mail: dev@issp.ac.ru [Russian Academy Sciences, Institute of Solid State Physics (Russian Federation)
2016-11-15
We experimentally investigate spin-polarized electron transport between a permalloy ferromagnet and the edge of a two-dimensional electron system with band inversion, realized in a narrow, 8 nm wide, HgTe quantum well. In zero magnetic field, we observe strong asymmetry of the edge potential distribution with respect to the ferromagnetic ground lead. This result indicates that the helical edge channel, specific for the structures with band inversion even at the conductive bulk, is strongly coupled to the ferromagnetic side contact, possibly due to the effects of proximity magnetization. This allows selective and spin-sensitive contacting of helical edge states.
Wallraff, A; Schuster, D I; Blais, A; Gambetta, J M; Schreier, J; Frunzio, L; Devoret, M H; Girvin, S M; Schoelkopf, R J
2007-08-03
Sideband transitions are spectroscopically probed in a system consisting of a Cooper pair box strongly but nonresonantly coupled to a superconducting transmission line resonator. When the Cooper pair box is operated at the optimal charge bias point, the symmetry of the Hamiltonian requires a two-photon process to access sidebands. The observed large dispersive ac-Stark shifts in the sideband transitions induced by the strong nonresonant drives agree well with our theoretical predictions. Sideband transitions are important in realizing qubit-photon and qubit-qubit entanglement in the circuit quantum electrodynamics architecture for quantum information processing.
Negative tunneling magneto-resistance in quantum wires with strong spin-orbit coupling.
Han, Seungju; Serra, Llorenç; Choi, Mahn-Soo
2015-07-01
We consider a two-dimensional magnetic tunnel junction of the FM/I/QW(FM+SO)/I/N structure, where FM, I and QW(FM+SO) stand for a ferromagnet, an insulator and a quantum wire with both magnetic ordering and Rashba spin-orbit (SOC), respectively. The tunneling magneto-resistance (TMR) exhibits strong anisotropy and switches sign as the polarization direction varies relative to the quantum-wire axis, due to interplay among the one-dimensionality, the magnetic ordering, and the strong SOC of the quantum wire.
International Nuclear Information System (INIS)
Vallurupalli, Pramodh; Scott, Lincoln; Williamson, James R.; Kay, Lewis E.
2007-01-01
Simulation and experiment have been used to establish that significant artifacts can be generated in X-pulse CPMG relaxation dispersion experiments recorded on heteronuclear ABX spin-systems, such as 13 C i - 13 C j - 1 H, where 13 C i and 13 C j are strongly coupled. A qualitative explanation of the origin of these artifacts is presented along with a simple method to significantly reduce them. An application to the measurement of 1 H CPMG relaxation dispersion profiles in an HIV-2 TAR RNA molecule where all ribose sugars are protonated at the 2' position, deuterated at all other sugar positions and 13 C labeled at all sugar carbons is presented to illustrate the problems that strong 13 C- 13 C coupling introduces and a simple solution is proposed
Energy Technology Data Exchange (ETDEWEB)
Malaescu, B. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Starovoitov, P. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2012-03-15
We perform a determination of the strong coupling constant using the latest ATLAS inclusive jet cross section data, from proton-proton collisions at {radical}(s)=7 TeV, and their full information on the bin-to-bin correlations. Several procedures for combining the statistical information from the different data inputs are studied and compared. The theoretical prediction is obtained using NLO QCD, and it also includes non-perturbative corrections. Our determination uses inputs with transverse momenta between 45 and 600 GeV, the running of the strong coupling being also tested in this range. Good agreement is observed when comparing our result with the world average at the Z-boson scale, as well as with the most recent results from the Tevatron. (orig.)
Casalderrey-Solana, Jorge; Milhano, Jose Guilherme; Pablos, Daniel; Rajagopal, Krishna
2016-06-11
We confront a hybrid strong/weak coupling model for jet quenching to data from LHC heavy ion collisions. The model combines the perturbative QCD physics at high momentum transfer and the strongly coupled dynamics of non- abelian gauge theories plasmas in a phenomenological way. By performing a full Monte Carlo simulation, and after fitting one single parameter, we successfully describe several jet observables at the LHC, including dijet and photon jet measurements. Within current theoretical and experimental uncertainties, we find that such observables show little sensitivity to the specifics of the microscopic energy loss mechanism. We also present a new observable, the ratio of the fragmentation function of inclusive jets to that of the associated jets in dijet pairs, which can discriminate among different medium models. Finally, we discuss the importance of plasma response to jet passage in jet shapes.
Effect of the strong coupling on the exchange bias field in IrMn/Py/Ru/Co spin valves
Tarazona, H. S.; Alayo, W.; Landauro, C. V.; Quispe-Marcatoma, J.
2018-01-01
The IrMn/Py/Ru/Co (Py = Ni81Fe19) spin valves have been produced by sputtering deposition and analyzed by magnetization measurements and a theoretical modelling of their exchange interactions, based on the macro-spin model. The Ru thickness was grown between 6 and 22 Å, which is small enough to promote strong indirect coupling between Py and Co. Results of measurements showed a large and gradual change in the shape of hysteresis loops when the Ru thickness was varied. The theoretical analysis, using numerical calculations based on the gradient conjugate method, provides the exchange coupling constants (bilinear and biquadratic), the exchange anisotropy fields and the magnetic anisotropy fields (uniaxial and rotatable). The exchange bias fields of spin valves were compared to that of a IrMn/Py bilayer. We found that the difference between these fields oscillates with Ru thickness in the same manner as the bilinear coupling constants.
Vafek, Oskar; Chubukov, Andrey V.
2017-02-01
We present a novel mechanism of s -wave pairing in Fe-based superconductors. The mechanism involves holes near dx z/dy z pockets only and is applicable primarily to strongly hole doped materials. We argue that as long as the renormalized Hund's coupling J exceeds the renormalized interorbital Hubbard repulsion U', any finite spin-orbit coupling gives rise to s -wave superconductivity. This holds even at weak coupling and regardless of the strength of the intraorbital Hubbard repulsion U . The transition temperature grows as the hole density decreases. The pairing gaps are fourfold symmetric, but anisotropic, with the possibility of eight accidental nodes along the larger pocket. The resulting state is consistent with the experiments on KFe2 As2 .
Emission of strong Terahertz pulses from laser wakefields in weakly coupled plasma
Energy Technology Data Exchange (ETDEWEB)
Singh, Divya, E-mail: dsingh@rajdhani.du.ac.in [PWAPA Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110 016 (India); Department of Physics & Electronics, Rajdhani College, University of Delhi, Raja Garden, Ring Road, New Delhi 110015 (India); Malik, Hitendra K. [PWAPA Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110 016 (India)
2016-09-01
The present paper discusses the laser plasma interaction for the wakefield excitation and the role of external magnetic field for the emission of Terahertz radiation in a collisional plasma. Flat top lasers are shown to be more appropriate than the conventional Gaussian lasers for the effective excitation of wakefields and hence, the generation of strong Terahertz radiation through the transverse component of wakefield.
Sokhoyan, R.; Azizbekyan, H.; Leroy, C.; Ishkhanyan, A.
2011-04-01
We discuss the strong-coupling regime of the nonlinear Landau-Zener problem occurring at coherent photo- and magneto-association of ultracold atoms. We apply a variational approach to an exact third-order nonlinear differential equation for the molecular state probability and construct an accurate approximation describing the time dynamics of the coupled atom-molecule system. The resultant solution improves the accuracy of the previous approximation [22]. The obtained results reveal a remarkable observation that in the strong-coupling limit, the resonance crossing is mostly governed by the nonlinearity, while the coherent atom-molecule oscillations occurring soon after crossing the resonance are principally of a linear nature. This observation is supposedly general for all nonlinear quantum systems having the same generic quadratic nonlinearity, due to the basic attributes of the resonance crossing processes in such systems. The constructed approximation turns out to have a larger applicability range than it was initially expected, covering the whole moderate-coupling regime for which the proposed solution accurately describes ail the main characteristics of the system evolution except the amplitude of the coherent atom-molecule oscillation, which is rather overestimated.
Yang, Bowen; Lohmann, Mark; Barroso, David; Liao, Ingrid; Lin, Zhisheng; Liu, Yawen; Bartels, Ludwig; Watanabe, Kenji; Taniguchi, Takashi; Shi, Jing
2017-07-01
Despite its extremely weak intrinsic spin-orbit coupling (SOC), graphene has been shown to acquire considerable SOC by proximity coupling with exfoliated transition metal dichalcogenides (TMDs). Here we demonstrate strong induced Rashba SOC in graphene that is proximity coupled to a monolayer TMD film, Mo S2 or WS e2 , grown by chemical-vapor deposition with drastically different Fermi level positions. Graphene/TMD heterostructures are fabricated with a pickup-transfer technique utilizing hexagonal boron nitride, which serves as a flat template to promote intimate contact and therefore a strong interfacial interaction between TMD and graphene as evidenced by quenching of the TMD photoluminescence. We observe strong induced graphene SOC that manifests itself in a pronounced weak-antilocalization (WAL) effect in the graphene magnetoconductance. The spin-relaxation rate extracted from the WAL analysis varies linearly with the momentum scattering time and is independent of the carrier type. This indicates a dominantly Dyakonov-Perel spin-relaxation mechanism caused by the induced Rashba SOC. Our analysis yields a Rashba SOC energy of ˜1.5 meV in graphene/WS e2 and ˜0.9 meV in graphene/Mo S2 . The nearly electron-hole symmetric nature of the induced Rashba SOC provides a clue to possible underlying SOC mechanisms.
A bridge between weak and strong coupling regions: BRS symmetries as a guiding principle
International Nuclear Information System (INIS)
Shintani, M.
1987-04-01
By imposing extended BRS symmetries on the Yang-Mills Lagrangian, we obtained two types of BRS invariant Lagrangians, i.e. Lagrangians of the non-gauge type and the gauge type. A Lagrangian of the non-gauge type, which was previously obtained by us, can yield the linearly rising potential between a quark and anti-quark pair at the one-loop level. By smoothly relating the running coupling constant in the confining region to that in the asymptotically free region, we deduce a relationship between the string tensions and Λ QCD , which shows good agreement with experiments. (author). 20 refs, 1 fig
Thermal spectral functions of strongly coupled N = 4 supersymmetric Yang-Mills theory.
Kovtun, Pavel; Starinets, Andrei
2006-04-07
We use the gauge-gravity duality conjecture to compute spectral functions of the stress-energy tensor in finite-temperature N = 4 supersymmetric Yang-Mills theory in the limit of large N(c) and large 't Hooft coupling. The spectral functions exhibit peaks characteristic of hydrodynamic modes at small frequency, and oscillations at intermediate frequency. The nonperturbative spectral functions differ qualitatively from those obtained in perturbation theory. The results may prove useful for lattice studies of transport processes in thermal gauge theories.
Non-perturbative computation of the strong coupling constant on the lattice
International Nuclear Information System (INIS)
Sommer, Rainer; Humboldt-Universitaet, Berlin; Wolff, Ulli
2015-01-01
We review the long term project of the ALPHA collaboration to compute in QCD the running coupling constant and quark masses at high energy scales in terms of low energy hadronic quantities. The adapted techniques required to numerically carry out the required multiscale non-perturbative calculation with our special emphasis on the control of systematic errors are summarized. The complete results in the two dynamical flavor approximation are reviewed and an outlook is given on the ongoing three flavor extension of the programme with improved target precision.
Plasmon mass and Drude weight in strongly spin-orbit-coupled 2D electron gases
Czech Academy of Sciences Publication Activity Database
Agarwal, A.; Chesi, S.; Jungwirth, Tomáš; Sinova, Jairo; Vignale, G.; Polini, M.
2011-01-01
Roč. 83, č. 11 (2011), 115135/1-115135/16 ISSN 1098-0121 R&D Projects: GA AV ČR KAN400100652; GA MŠk LC510 EU Projects: European Commission(XE) 215368 - SemiSpinNet Grant - others:AV ČR(CZ) AP0801 Program:Akademická prémie - Praemium Academiae Institutional research plan: CEZ:AV0Z10100521 Keywords : two-dimensional systems * spin-orbit coupling Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.691, year: 2011
Strong coupling between 0D and 2D modes in optical open microcavities
Trichet, A. A. P.; Dolan, P. R.; Smith, J. M.
2018-02-01
We present a study of the coupling between confined modes and continuum states in an open microcavity system. The confined states are the optical modes of a plano-concave Fabry–Pérot cavity while the continuum states are the propagating modes in a surrounding planar cavity. The length tunability of the open cavity system allows to study the evolution of localised modes as they are progressively deconfined and coupled to the propagating modes. We observe an anti-crossing between the confined and propagating modes proving that mode-mixing takes place in between these two families of modes, and identify 0D–2D mixed modes which exhibit reduced loss compared with their highly localised counterparts. For practical design, we investigate the details of the microcavity shape that can be used to engineer the degree of mode-mixing. This study discusses for the first time experimentally and theoretically how light confinement arises in planar micromirrors and is of interest for the realisation of chip-based extended microphotonics using open cavities.
Hawking radiation from small black holes at strong coupling and large N
Haddad, Nidal
2013-10-01
In a previous work an approximate static metric was found of a test black string that stretches from the boundary to the horizon of the planar Schwarzschild-AdS5 geometry. This is the gravity dual of the Unruh state for {N}=4, SU(N) super Yang-Mills theory on a four-dimensional Schwarzschild background, at large N and large ’tHooft coupling. We compute the holographic stress tensor of the gravitational solution and it turns out to possess many essential features of the Unruh state for weakly coupled Hawking radiation, such as the appearance of a negative energy density near the black hole horizon and a positive energy density at infinity. It also confirms recent results that at leading order in N, the expectation value of the stress tensor in the Unruh state is finite on both the future and past horizons, and that at this order there are no flux terms as is expected in the black droplet phase.
Energy Technology Data Exchange (ETDEWEB)
Cao, X [Department of Physics and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen, 361005 (China); You, J Q; Nori, F [Advanced Science Institute, RIKEN, Wako-shi 351-0198 (Japan); Zheng, H, E-mail: xfcao@xmu.edu.cn [Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China)
2011-07-15
We investigate the spontaneous emission (SE) spectrum of a qubit in a lossy resonant cavity. We use neither the rotating-wave approximation nor the Markov approximation. For the weak-coupling case, the SE spectrum of the qubit is a single peak, with its location depending on the spectral density of the qubit environment. Then, the asymmetry (of the location and heights of the two peaks) of the two SE peaks (which are related to the vacuum Rabi splitting) changes as the qubit-cavity coupling increases. Explicitly, for a qubit in a low-frequency intrinsic bath, the height asymmetry of the splitting peaks is enhanced as the qubit-cavity coupling strength increases. However, for a qubit in an Ohmic bath, the height asymmetry of the spectral peaks is inverted compared to the low-frequency bath case. With further increasing the qubit-cavity coupling to the ultra-strong regime, the height asymmetry of the left and right peaks is slightly inverted, which is consistent with the corresponding case of a low-frequency bath. This inversion of the asymmetry arises from the competition between the Ohmic bath and the cavity bath. Therefore, after considering the anti-rotating terms, our results explicitly show how the height asymmetry in the SE spectrum peaks depends on the qubit-cavity coupling and the type of intrinsic noise experienced by the qubit.
Kozin, V. K.; Iorsh, I. V.; Kibis, O. V.; Shelykh, I. A.
2018-01-01
We demonstrate theoretically that a strong high-frequency circularly polarized electromagnetic field can turn a two-dimensional periodic array of interconnected quantum rings into a topological insulator. The elaborated approach is applicable to calculate and analyze the electron energy spectrum of the array, the energy spectrum of the edge states, and the corresponding electronic densities. As a result, the present theory paves the way to optical control of the topological phases in ring-based mesoscopic structures.
Wave failure at strong coupling in intracellular C a2 + signaling system with clustered channels
Li, Xiang; Wu, Yuning; Gao, Xuejuan; Cai, Meichun; Shuai, Jianwei
2018-01-01
As an important intracellular signal, C a2 + ions control diverse cellular functions. In this paper, we discuss the C a2 + signaling with a two-dimensional model in which the inositol 1,4,5-trisphosphate (I P3 ) receptor channels are distributed in clusters on the endoplasmic reticulum membrane. The wave failure at large C a2 + diffusion coupling is discussed in detail in the model. We show that with varying model parameters the wave failure is a robust behavior with either deterministic or stochastic channel dynamics. We suggest that the wave failure should be a general behavior in inhomogeneous diffusing systems with clustered excitable regions and may occur in biological C a2 + signaling systems.
Strongly interacting vector bosons at the CERN LHC Quartic anomalous couplings
Belyaev, A; González-Garciá, M Concepción; Mizukoshi, J K; Novaes, S F; Zacharov, I E
1999-01-01
We analyze the potential of the CERN Large Hadron Collider to study anomalous quartic vector--boson interactions through the production of vector--boson pairs accompanied by jets. In the framework of $SU(2)_L \\otimes U(1)_Y$ chiral Lagrangians, we examine all effective operators of order $p^4$ that lead to new four--gauge--boson interactions but do not alter trilinear vertices. In our analyses, we perform the full tree level calculation of the processes leading to two jets plus vector--boson pairs, $W^+W^-$, $W^\\pm W^\\pm$, $W^\\pm Z$, or $ZZ$, taking properly into account the interference between the standard model and the anomalous contributions. We obtain the bounds that can be placed on the anomalous quartic interactions and we study the strategies to distinguish the possible new couplings.
Exchange bias and major coercivity enhancement in strongly-coupled CuO/Co films
Gamino, M.; de Andrade, A. M. H.; Salazar Cuaila, J. L.; Schmidt, J. E.; Skumryev, V.; Geshev, J.
2018-03-01
The exchange-bias properties of ferromagnetic, either Co or Ni, thin films deposited onto polycrystalline multiferroic CuO are investigated. After field cooling, the CuO/Co magnetization hysteresis loops show exchange bias at temperatures lower than 200 K, while the CuO/Ni system exhibits bias below about 5 K only. It is suggested that the exchange bias of CuO/Co is determined mainly by the magnetization reversal that takes place on the descending branch of the loop. Rather high values of both the interface coupling energy, 0.89 erg/cm2, and coercivity, 2.44 kOe, of the CuO/Co film are obtained at 5 K.
Slater Insulator in Iridate Perovskites with Strong Spin-Orbit Coupling
Energy Technology Data Exchange (ETDEWEB)
Cui, Q.; Cheng, J. -G.; Fan, W.; Taylor, A. E.; Calder, S.; McGuire, M. A.; Yan, J. -Q.; Meyers, D.; Li, X.; Cai, Y. Q.; Jiao, Y. Y.; Choi, Y.; Haskel, D.; Gotou, H.; Uwatoko, Y.; Chakhalian, J.; Christianson, A. D.; Yunoki, S.; Goodenough, J. B.; Zhou, J. -S.
2016-10-20
The perovskite (Pv) SrIrO_{3} is an exotic narrow-band metal owing to a confluence of the strengths of the spin-orbit coupling (SOC) and the electron-electron correlations. It has been proposed that topological and magnetic insulating phases can be achieved by tuning the SOC, Hubbard interactions, and/or lattice symmetry. Here, we report that the substitution of nonmagnetic, isovalent Sn^{4+} for Ir^{4+} in the SrIr_{1-x}Sn_{x}O_{3} perovskites synthesized under high pressure leads to a metal-insulator transition to an antiferromagnetic phase at TN ≥ 225 K. The continuous change of the cell volume as detected by X-ray diffraction and the l-shape transition of the specific heat on cooling through TN demonstrate that the metal-insulator transition is of second-order. Neutron powder diffraction results indicate that the Sn substitution enlarges an octahedral-site distortion that reduces the SOC relative to the spin-spin exchange interaction and results in the type-G AF spin ordering below TN. Measurement of high-temperature magnetic susceptibility shows the evolution of magnetic coupling in the paramagnetic phase typical of weak itinerant-electron magnetism in the Sn-substituted samples. A reduced structural symmetry in the magnetically ordered phase leads to an electron gap opening at the Brillouin zone boundary below TN in the same way as proposed by Slater.
Rocha, Reginaldo C; Brown, Mac G; Londergan, Casey H; Salsman, J Catherine; Kubiak, Clifford P; Shreve, Andrew P
2005-10-13
Resonance Raman spectroelectrochemistry (RR-SEC) at -20 degrees C has been performed on the pyrazine-bridged dimer of mu-oxo-centered trinuclear ruthenium-acetate "clusters"--[(dmap)(CO)(mu-OAc)6(mu3-O)Ru3(mu-L(b))Ru3(mu3-O)(mu-OAc)6(CO)(dmap)]n (where dmap = 4-(dimethylamino)pyridine and L(b) = pyrazine-h4 and pyrazine-d4)-in three oxidation states: n = 0, -1, and -2. In the one-electron reduced, "mixed-valent" state (overall -1 charge and a single odd electron; formal oxidation states [II, II, III]-[III, III, II] on the metal centers), the Raman excitation at 800 nm is resonant with a cluster-to-cluster intervalence charge-transfer (IVCT) band. Under these conditions, scattering enhancement is observed for all four totally symmetric vibrational modes of the bridging pyrazine ligand (nu8a, nu9a, nu1, and nu6a) in the investigated spectral range (100-2000 cm(-1)), and there is no evidence of activity in non-totally symmetric vibrations. Resonantly enhanced Raman peaks related to peripheral pyridyl (dmap) ligand modes and low-frequency features arising from the trigonal Ru3O cluster core and the cluster[Ru]-[N]ligand vibrations were also observed in the spectra of the intermediate-valence (n = -1) cluster dimer. The vibrational assignments and interpretations proposed in this work were reinforced by observation of characteristic isotopic frequency shifts accompanying deuteration of the bridging pyrazine. The results reveal that the fully symmetric (A(g)) vibrational motions of the organic bridge are coupled to the nominally metal cluster-to-metal cluster fast intramolecular electron transfer (ET) and provide validation of the near-delocalized description according to a predicted three-site/three-state (e.g., metal-bridge-metal) vibronic coupling model, in which the important role of the bridging ligand in mediating electronic communication and delocalization between charge centers is explicitly considered. Further compelling evidence supporting an extended five
Farabi, Sarah S; Carley, David W; Quinn, Lauretta
2017-05-01
Glucose variations are common throughout sleep and wakefulness in people with type 1 diabetes mellitus (T1DM). The objective of this investigation was to characterize the time-varying coupling between glucose and unstructured physical activity over a 60-hr period in young adults with T1DM. The hypothesis was that coupling would differ during sleep versus wakefulness and would exhibit circadian variations. Young adults with T1DM treated with an insulin pump participated in the study. Glucose variations were monitored with a continuous glucose monitoring system, and activity was assessed using an activity-monitoring band worn on the nondominant wrist. Simultaneous glucose and physical activity data across a continuous 60-hr period were used for analysis. Wavelet coherence analysis was employed to quantify the coupling between physical activity and glucose. Cosinor analysis was used to assess whether glucose/activity coherence exhibited significant circadian variations. Participants comprised 23 adults, aged 18-30 years, with T1DM. Coherence analysis demonstrated substantial coupling between physical activity and glucose variations during both wakefulness and sleep. For rapid (10-30 min) fluctuations, mean coherence was higher during sleep than wakefulness ( F = 10.86, p = .003). Rapid glucose variations consistently led to changes in activity ( p = .001) during sleep but not during wake. Cosinor analysis revealed significant circadian modulation of glucose/activity coupling, especially for fluctuation periods 2-4 hr. Unstructured physical activity and glucose variations demonstrated strong time- and frequency-dependent coupling over a 60-hr period in young adults with T1DM, with sleep/wake differences and circadian modulation evident in this relationship.
Continuous Time Monte Carlo for Lattice QCD in the Strong Coupling Limit
Unger, Wolfgang
2011-01-01
We present results for lattice QCD with staggered fermions in the limit of infinite gauge coupling, obtained from a worm-type Monte Carlo algorithm on a discrete spatial lattice but with continuous Euclidean time. This is achieved by sending both the anisotropy parameter $\\gamma^2\\simeq a/\\at$ and the number of time-slices $N_\\tau$ to infinity, keeping the ratio $\\gamma^2/N_\\tau \\simeq aT$ fixed. In this limit, ambiguities arising from the anisotropy parameter $\\gamma$ are eliminated and discretization errors usually introduced by a finite temporal lattice extent $\\Nt$ are absent. The obvious gain is that no continuum extrapolation $N_\\tau \\rightarrow \\infty$ has to be carried out. Moreover, the algorithm is faster and the sign problem disappears completely. As a first application, we determine the phase diagram as a function of temperature and real and imaginary baryon chemical potential. We compare our computations with those on lattices with discrete Euclidean time. Discretization errors due to finite $\\Nt...
Bridging the Gap for High-Coherence, Strongly Coupled Superconducting Qubits
Yoder, Jonilyn; Kim, David; Baldo, Peter; Day, Alexandra; Fitch, George; Holihan, Eric; Hover, David; Samach, Gabriel; Weber, Steven; Oliver, William
Crossovers can play a critical role in increasing superconducting qubit device performance, as long as device coherence can be maintained even with the increased fabrication and circuit complexity. Specifically, crossovers can (1) enable a fully-connected ground plane, which reduces spurious modes and crosstalk in the circuit, and (2) increase coupling strength between qubits by facilitating interwoven qubit loops with large mutual inductances. Here we will describe our work at MIT Lincoln Laboratory to integrate superconducting air bridge crossovers into the fabrication of high-coherence capacitively-shunted superconducting flux qubits. We will discuss our process flow for patterning air bridges by resist reflow, and we will describe implementation of air bridges within our circuits. This research was funded in part by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA) and by the Assistant Secretary of Defense for Research and Engineering under Air Force Contract No. FA8721-05-C-0002. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of ODNI, IARPA, or the US Government.
Strong Coupling and Bounds on the Spin-2 Mass in Massive Gravity
Burrage, Clare; Kaloper, Nemanja; Padilla, Antonio
2013-07-01
The de Rham-Gabadadze-Tolley theory of a single massive spin-2 field has a cutoff much below its Planck scale because the extra modes from the massive spin-2 multiplet involve higher derivative self-interactions, controlled by a scale convoluted from its mass. Generically, these correct the propagator by environmental effects. The resulting effective cutoff depends on the environmental parameters and the spin-2 “graviton” mass. Requiring the theory to be perturbative down to O(1)mm, we derive bounds on the mass, corresponding to ≳O(1)meV for the generic case, assuming the coupling to be given by the standard Newton’s constant, and somewhat weaker bounds in cases with fine-tuning. Thus, the theory of a single massive spin-2 can really only be viewed as a theory describing the full nonlinear propagation of a massive spin-2 field on a fixed background and not as an approximation to general relativity.
Li, Guang-Hui; Wang, An-Bang; Feng, Ye; Wang, Yang
2010-07-01
This paper numerically demonstrates synchronization and bidirectional communication without delay line by using two semiconductor lasers with strong mutual injection in a face-to-face configuration. These results show that both of the two lasers' outputs synchronize with their input chaotic carriers. In addition, simulations demonstrate that this kind of synchronization can be used to realize bidirectional communications without delay line. Further studies indicate that within a small deviation in message amplitudes of two sides (±6%), the message can be extracted with signal-noise-ratio more than 10 dB; and the signal-noise-ratio is extremely sensitive to the message rates mismatch of two sides, which may be used as a key of bidirectional communication.
Exploring the physics of superconducting qubits strongly coupled to microwave frequency photons
Energy Technology Data Exchange (ETDEWEB)
Wallraff, Andreas [ETH Zurich (Switzerland)
2013-07-01
Using modern micro and nano-fabrication techniques combined with superconducting materials we realize electronic circuits the properties of which are governed by the laws of quantum mechanics. In such circuits the strong interaction of photons with superconducting quantum two-level systems allows us to probe fundamental quantum properties of light and to develop components for applications in quantum information technology. Here, I present experiments in which we have created and probed entanglement between stationary qubits and microwave photons freely propagating down a transmission line. In these experiments we use superconducting parametric amplifiers realized in our lab to detect both qubit and photon states efficiently. Using similar techniques we aim at demonstrating a deterministic scheme for teleportation of quantum states in a macroscopic system based on superconducting circuits.
International Nuclear Information System (INIS)
Protopapas, P.; Klein, A.
1997-01-01
We review briefly the fundamental equations of a semimicroscopic core-particle coupling method that makes no reference to an intrinsic system of coordinates. We then demonstrate how an intrinsic system can be introduced in the strong coupling limit so as to yield a completely equivalent formulation. It is emphasized that the conventional core-particle coupling calculation introduces a further approximation that avoids what has hitherto been the most time-consuming feature of the full theory, and that this approximation can be introduced either in the intrinsic system, the usual case, or in the laboratory system, our preference. A new algorithm is described for the full theory that largely removes the difference in complexity between the two types of calculation. Comparison of the full and approximate theories for some representative cases provides a basis for the assessment of the accuracy of the traditional approach. We find that for well-deformed nuclei, e.g., 157 Gd and 157 Tb, the core-coupling method and the full theory give similar results. copyright 1997 The American Physical Society
Energy Technology Data Exchange (ETDEWEB)
Chung, Y. D.; Lee, S. Y.; Lee, T. W.; Kim, J. S. [Suwon Science College, Suwon (Korea, Republic of); Lee, C. Y. [Korea Railroad Institute, Uiwang (Korea, Republic of)
2016-03-15
The technology of supplying the electric power by wireless power transfer (WPT) is expected for the next generation power feeding system since it can supply the power to portable devices without any connectors through large air gap. As such a technology based on strongly coupled electromagnetic resonators is possible to deliver the large power and recharge them seamlessly; it has been considered as a noble option to wireless power charging system in the various power applications. Recently, various HTS wires have now been manufactured for demonstrations of transmission cables, motors, MAGLEV, and other electrical power components. However, since the HTS magnets have a lower index n value intrinsically, they are required to be charged from external power system through leads or internal power system. The portable area is limited as well as the cryogen system is bulkier. Thus, we proposed a novel design of wireless power charging system for superconducting HTS magnet (WPC4SM) based on resonance coupling method. As the novel system makes possible a wireless power charging using copper resonance coupled coils, it enables to portable charging conveniently in the superconducting applications. This paper presented the conceptual design and operating characteristics of WPC4SM using different shapes' copper resonance coil. The proposed system consists of four components; RF generator of 370 kHz, copper resonance coupling coils, impedance matching (IM) subsystem and HTS magnet including rectifier system.
Kim, Junyeon; Karube, Shutaro; Chen, Yan-Ting; Kondou, Kouta; Tatara, Gen; Otani, YoshiChika
2016-10-01
Spin-charge conversion induced by spin-orbit coupling (SOC) is attractive topic for alternative magnetization manipulation and involved various novel phenomena. Particularly Bi-based structure draws interest due to its large Rashba-Edelstein effect (REE) at interface between non-magnetic metal and Bi [1]. A recent report showed that spin-to-charge current conversion becomes more efficient when Bi2O3 is employed on behalf of the Bi [2]. Here we report novel type of magnetoresistance (MR) in Co25Fe75/Cu/Bi2O3 multilayer. This novel MR comes from conversion between spin and charge current at Cu/Bi2O3 interface, and distinctive spin transfer torque dependent on magnetization of the ferromagnetic Co25Fe75 layer. A Co25Fe75 (5)/Cu (0-30)/Bi2O3 (20) (unit:nm) multilayer was deposited with electron beam evaporation on shadow masked Si substrate. Hall bar shaped shadow mask was patterned with photo-lithography method. The MR measurement was performed via 4-point probe method with changing magnitude or angle of external field. Note that external field for angle dependent measurement was 6 T to make sure complete saturation of ferromagnetic layer. We found characteristic resistance drop when the magnetization of ferromagnetic layer is parallel to magnetic direction of spin accumulation, which is similar to spin Hall magnetoresistance (SMR) [3,4]. Further discussion will be given. [1] J. C. Rojas Sanchez et al. Nature Comm. 4, 2944 (2013). [2] S. Karube et al. Appl. Phys. Express. 9, 03301 (2016). [3] H. Nakayama et al. Phys. Rev. Lett. 110, 206601 (2013). [4] J. Kim et al. Phys. Rev. Lett. (in press).
International Nuclear Information System (INIS)
Gregori, G.; Hansen, S.B.; Key, M.H.; King, J.; Mackinnon, A.J.; Park, H.; Patel, P.K.; Shepard, R.; Snavely, R.A.; Wilks, S.C.; Glenzer, S.H.
2005-01-01
We have measured high resolution copper Kα spectra from a picosecond high intensity laser produced plasma. By fitting the shape of the experimental spectra with a self-consistent-field model which includes all the relevant line shifts from multiply ionized atoms, we are able to infer time and spatially averaged electron temperatures (T e ) and ionization state (Z) in the foil. Our results show increasing values for T e and Z when the overall mass of the target is reduced. In particular, we measure temperatures in excess of 200 eV with Z ∼ 13-14. For these conditions the ion-ion coupling constant is Λ ii ∼ 8-9, thus suggesting the achievement of a strongly coupled plasma regime
Abazov, V.M.; et al., [Unknown; Ancu, L.S.; de Jong, S.J.; Filthaut, F.; Galea, C.F.; Hegeman, J.G.; Houben, P.; Meijer, M.M.; Svoisky, P.; van den Berg, P.J.; van Leeuwen, W.M.
2009-01-01
We determine the strong coupling constant alpha(s) and its energy dependence from the p(T) dependence of the inclusive jet cross section in pp collisions at s=1.96 TeV. The strong coupling constant is determined over the transverse momentum range 50 < p(T)< 145 GeV. Using perturbative QCD
The topological structures in strongly coupled QGP with chiral fermions on the lattice
Energy Technology Data Exchange (ETDEWEB)
Sharma, Sayantan [Physics Department, Brookhaven National Laboratory, Upton, New York-11973 (United States); Dick, Viktor [Fakultät für Physik, Universität Bielefeld, Universitätstasse 25, D33619 Bielefeld (Germany); Karsch, Frithjof [Physics Department, Brookhaven National Laboratory, Upton, New York-11973 (United States); Fakultät für Physik, Universität Bielefeld, Universitätstasse 25, D33619 Bielefeld (Germany); Laermann, Edwin [Fakultät für Physik, Universität Bielefeld, Universitätstasse 25, D33619 Bielefeld (Germany); Mukherjee, Swagato [Physics Department, Brookhaven National Laboratory, Upton, New York-11973 (United States)
2016-12-15
The nature of chiral phase transition for two flavor QCD is an interesting but unresolved problem. One of the most intriguing issues is whether or not the anomalous U(1) symmetry in the flavor sector is effectively restored along with the chiral symmetry. This may determine the universality class of the chiral phase transition. Since the physics near the chiral phase transition is essentially non-perturbative, we employ first principles lattice techniques to address this issue. We use overlap fermions, which have exact chiral symmetry on the lattice, to probe the anomalous U(1) symmetry violation of 2+1 flavor dynamical QCD configurations with domain wall fermions. The latter also optimally preserves chiral and flavor symmetries on the lattice, since it is known that the remnant chiral symmetry of the light quarks influences the scaling of the chiral condensate in the crossover transition region. We observe that the anomalous U(1) is not effectively restored in the chiral crossover region. We perform a systematic study of the finite size and cut-off effects since the signals of U(1) violation are sensitive to it. We also provide a glimpse of the microscopic topological structures of the QCD medium that are responsible for the strongly interacting nature of the quark gluon plasma phase. We study the effect of these microscopic constituents through our first calculations for the topological susceptibility of QCD at finite temperature, which could be a crucial input for the equation of state for anomalous hydrodynamics.
Strong coupling constant extraction from high-multiplicity $Z+\text{jets}$ observables
Johnson, Mark; Maître, Daniel
2018-01-01
We present a strong coupling constant extraction at next-to-leading order QCD accuracy using ATLAS Z+2,3,4 jets data. This is the first extraction using processes with a dependency on high powers of the coupling constant. We obtain values of the strong coupling constant at the Z mass compatible with the world average and with uncertainties commensurate with other next-to-leading order extractions at hadron colliders. Our most conservative result for the strong coupling constant is αS(MZ)=0.11...
Integrated fiber-mirror ion trap for strong ion-cavity coupling
International Nuclear Information System (INIS)
Brandstätter, B.; Schüppert, K.; Casabone, B.; Friebe, K.; Stute, A.; Northup, T. E.; McClung, A.; Schmidt, P. O.; Deutsch, C.; Reichel, J.; Blatt, R.
2013-01-01
We present and characterize fiber mirrors and a miniaturized ion-trap design developed to integrate a fiber-based Fabry-Perot cavity (FFPC) with a linear Paul trap for use in cavity-QED experiments with trapped ions. Our fiber-mirror fabrication process not only enables the construction of FFPCs with small mode volumes, but also allows us to minimize the influence of the dielectric fiber mirrors on the trapped-ion pseudopotential. We discuss the effect of clipping losses for long FFPCs and the effect of angular and lateral displacements on the coupling efficiencies between cavity and fiber. Optical profilometry allows us to determine the radii of curvature and ellipticities of the fiber mirrors. From finesse measurements, we infer a single-atom cooperativity of up to 12 for FFPCs longer than 200 μm in length; comparison to cavities constructed with reference substrate mirrors produced in the same coating run indicates that our FFPCs have similar scattering losses. We characterize the birefringence of our fiber mirrors, finding that careful fiber-mirror selection enables us to construct FFPCs with degenerate polarization modes. As FFPCs are novel devices, we describe procedures developed for handling, aligning, and cleaning them. We discuss experiments to anneal fiber mirrors and explore the influence of the atmosphere under which annealing occurs on coating losses, finding that annealing under vacuum increases the losses for our reference substrate mirrors. X-ray photoelectron spectroscopy measurements indicate that these losses may be attributable to oxygen depletion in the mirror coating. Special design considerations enable us to introduce a FFPC into a trapped ion setup. Our unique linear Paul trap design provides clearance for such a cavity and is miniaturized to shield trapped ions from the dielectric fiber mirrors. We numerically calculate the trap potential in the absence of fibers. In the experiment additional electrodes can be used to compensate
Brewer, Jasmine; Rajagopal, Krishna; Sadofyev, Andrey; van der Schee, Wilke
2018-02-01
Some of the most important experimentally accessible probes of the quark- gluon plasma (QGP) produced in heavy ion collisions come from the analysis of how the shape and energy of sprays of energetic particles produced within a cone with a specified opening angle (jets) in a hard scattering are modified by their passage through the strongly coupled, liquid, QGP. We model an ensemble of back-to-back dijets for the purpose of gaining a qualitative understanding of how the shapes of the individual jets and the asymmetry in the energy of the pairs of jets in the ensemble are modified by their passage through an expanding cooling droplet of strongly coupled plasma, in the model in a holographic gauge theory that is dual to a 4+1-dimensional black-hole spacetime that is asymptotically anti-de Sitter (AdS). We build our model by constructing an ensemble of strings in the dual gravitational description of the gauge theory. We model QCD jets in vacuum using strings whose endpoints are moving "downward" into the gravitational bulk spacetime with some fixed small angle, an angle that represents the opening angle (ratio of jet mass to jet energy) that the QCD jet would have in vacuum. Such strings must be moving through the gravitational bulk at (close to) the speed of light; they must be (close to) null. This condition does not specify the energy distribution along the string, meaning that it does not specify the shape of the jet being modeled. We study the dynamics of strings that are initially not null and show that strings with a wide range of initial conditions rapidly accelerate and become null and, as they do, develop a similar distribution of their energy density. We use this distribution of the energy density along the string, choose an ensemble of strings whose opening angles and energies are distributed as in perturbative QCD, and show that we can then fix one of the two model parameters such that the mean jet shape for the jets in the ensemble that we have built
Finite-size effect of η-deformed AdS5×S5 at strong coupling
Directory of Open Access Journals (Sweden)
Changrim Ahn
2017-04-01
Full Text Available We compute Lüscher corrections for a giant magnon in the η-deformed (AdS5×S5η using the su(2|2q-invariant S-matrix at strong coupling and compare with the finite-size effect of the corresponding string state, derived previously. We find that these two results match and confirm that the su(2|2q-invariant S-matrix is describing world-sheet excitations of the η-deformed background.
International Nuclear Information System (INIS)
Dahmen, Bernd
1994-01-01
A systematic method to obtain strong coupling expansions for scattering quantities in hamiltonian lattice field theories is presented. I develop the conceptual ideas for the case of the hamiltonian field theory analogue of the Ising model, in d space and one time dimension. The main result is a convergent series representation for the scattering states and the transition matrix. To be explicit, the special cases of d=1 and d=3 spatial dimensions are discussed in detail. I compute the next-to-leading order approximation for the phase shifts. The application of the method to investigate low-energy scattering phenomena in lattice gauge theory and QCD is proposed. ((orig.))
Finite-size effect of η-deformed AdS5 × S5 at strong coupling
Ahn, Changrim
2017-04-01
We compute Lüscher corrections for a giant magnon in the η-deformed (AdS5×S5)η using the su(2 | 2) q-invariant S-matrix at strong coupling and compare with the finite-size effect of the corresponding string state, derived previously. We find that these two results match and confirm that the su(2 | 2) q-invariant S-matrix is describing world-sheet excitations of the η-deformed background.
Ricci solitons, Ricci flow and strongly coupled CFT in the Schwarzschild Unruh or Boulware vacua
Figueras, Pau; Lucietti, James; Wiseman, Toby
2011-11-01
The elliptic Einstein-DeTurck equation may be used to numerically find Einstein metrics on Riemannian manifolds. Static Lorentzian Einstein metrics are considered by analytically continuing to Euclidean time. The Ricci-DeTurck flow is a constructive algorithm to solve this equation, and is simple to implement when the solution is a stable fixed point, the only complication being that Ricci solitons may exist which are not Einstein. Here we extend previous work to consider the Einstein-DeTurck equation for Riemannian manifolds with boundaries, and those that continue to static Lorentzian spacetimes which are asymptotically flat, Kaluza-Klein, locally AdS or have extremal horizons. Using a maximum principle, we prove that Ricci solitons do not exist in these cases and so any solution is Einstein. We also argue that the Ricci-DeTurck flow preserves these classes of manifolds. As an example, we simulate the Ricci-DeTurck flow for a manifold with asymptotics relevant for AdS5/CFT4. Our maximum principle dictates that there are no soliton solutions, and we give strong numerical evidence that there exists a stable fixed point of the flow which continues to a smooth static Lorentzian Einstein metric. Our asymptotics are such that this describes the classical gravity dual relevant for the CFT on a Schwarzschild background in either the Unruh or Boulware vacua. It determines the leading O(N2c) part of the CFT stress tensor, which interestingly is regular on both the future and past Schwarzschild horizons.
Ricci solitons, Ricci flow and strongly coupled CFT in the Schwarzschild Unruh or Boulware vacua
Energy Technology Data Exchange (ETDEWEB)
Figueras, Pau [DAMTP, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Lucietti, James [School of Mathematics and Maxwell Institute for Mathematical Sciences, University of Edinburgh, King' s Buildings, Edinburgh EH9 3JZ (United Kingdom); Wiseman, Toby, E-mail: t.wiseman@imperial.ac.uk [Theoretical Physics Group, Blackett Laboratory, Imperial College, London SW7 2AZ (United Kingdom)
2011-11-07
The elliptic Einstein-DeTurck equation may be used to numerically find Einstein metrics on Riemannian manifolds. Static Lorentzian Einstein metrics are considered by analytically continuing to Euclidean time. The Ricci-DeTurck flow is a constructive algorithm to solve this equation, and is simple to implement when the solution is a stable fixed point, the only complication being that Ricci solitons may exist which are not Einstein. Here we extend previous work to consider the Einstein-DeTurck equation for Riemannian manifolds with boundaries, and those that continue to static Lorentzian spacetimes which are asymptotically flat, Kaluza-Klein, locally AdS or have extremal horizons. Using a maximum principle, we prove that Ricci solitons do not exist in these cases and so any solution is Einstein. We also argue that the Ricci-DeTurck flow preserves these classes of manifolds. As an example, we simulate the Ricci-DeTurck flow for a manifold with asymptotics relevant for AdS{sub 5}/CFT{sub 4}. Our maximum principle dictates that there are no soliton solutions, and we give strong numerical evidence that there exists a stable fixed point of the flow which continues to a smooth static Lorentzian Einstein metric. Our asymptotics are such that this describes the classical gravity dual relevant for the CFT on a Schwarzschild background in either the Unruh or Boulware vacua. It determines the leading O(N{sup 2}{sub c}) part of the CFT stress tensor, which interestingly is regular on both the future and past Schwarzschild horizons. (paper)
Strongly coupled coulomb systems of dust particles in traps and plasmas
International Nuclear Information System (INIS)
Petrov, O.F.; Fortov, V.E.
2011-01-01
Complete text of publication follows. After first experimental observations of ordered structures of dust particles in rf and dc gas discharges, similar dusty plasma structures are frequently considered as a macroscopic physical model of coupled Coulomb systems (SCCS), which can visually be observed. Using such structures of charged dust particles, one can investigate the processes of phase transitions, waves, and instabilities on kinetic levels. One of the central problems associated with experimental studies of stable SCCS is that of ensuring the levitation of charged particles. The levitation of dust particles in gas discharges is provided by the interaction of the particle charge with electric field. For confinement and investigation of SCCS of charged dust particles, we propose to use a trap based on the known possibility of the levitation of diamagnetic bodies in a nonuniform steady-state magnetic field. An experimental setup is described, which is capable of forming and confining clusters of charge graphite particles sized 100 to 300 μm in magnetic field B∼1 T and |V-barB| ∼10 T/cm. It is inferred that it will be possible to form stable 3d dust structures containing several thousand particles under terrestrial conditions by using more intensive magnetic fields B > 10 T. Less intensive magnetic fields (B ∼ 0.1 T, |V-barB| ∼ 0.1 T/cm) will be required for studying analogous structures under microgravity conditions. The superhigh charging of dust particles under direct stimulation by an electron beam is experimentally investigated. The energy of beam electrons amounts to 25 keV, with the typical diameter of dust particles employed in the experiment of 100 μm. The charge acquired by a dust particle amounts to 5·10 7 electron charges, which is more than two orders of magnitude higher than the values of the charge of dust particles in gas discharges. A technique for analyzing the pair interaction forces between particles in nonideal dissipative systems
Directory of Open Access Journals (Sweden)
A. Stockklauser
2017-03-01
Full Text Available The strong coupling limit of cavity quantum electrodynamics (QED implies the capability of a matterlike quantum system to coherently transform an individual excitation into a single photon within a resonant structure. This not only enables essential processes required for quantum information processing but also allows for fundamental studies of matter-light interaction. In this work, we demonstrate strong coupling between the charge degree of freedom in a gate-defined GaAs double quantum dot (DQD and a frequency-tunable high impedance resonator realized using an array of superconducting quantum interference devices. In the resonant regime, we resolve the vacuum Rabi mode splitting of size 2g/2π=238 MHz at a resonator linewidth κ/2π=12 MHz and a DQD charge qubit decoherence rate of γ_{2}/2π=40 MHz extracted independently from microwave spectroscopy in the dispersive regime. Our measurements indicate a viable path towards using circuit-based cavity QED for quantum information processing in semiconductor nanostructures.
Effective potential in the strong-coupling lattice QCD with next-to-next-to-learning order effects
International Nuclear Information System (INIS)
Nakano, Takashi Z.; Miura, Kohtaroh; Ohnishi, Akira
2010-01-01
We derive an analytic expression of the effective potential at finite temperature (T) and chemical potential (μ) in the strong-coupling lattice QCD for color SU(3) including next-to-next-to-leading order (NNLO) effects in the strong coupling expansion. NNLO effective action terms are systematically evaluated in the leading order of the large dimensional (1/d) expansion, and are found to come from some types of connected two-plaquette configurations. We apply the extended Hubbard-Stratonovich transformation and a gluonic-dressed fermion technique to the effective action, and obtain the effective potential as a function of T, μ, and two order parameters: chiral condensate and vector potential field. The next-to-leading order (NLO) and NNLO effects result in modifications of the wave function renormalization factor, quark mass, and chemical potential. We find that T c,μ =0 and μ c,T =0 are similar to the NLO results, whereas the position of the critical point is sensitive to NNLO corrections. (author)
Chesler, Paul M.
We study dynamics in conformal field theories with gravitational duals. Attention is focused on heavy and light quark jets as well as far-from-equilibrium dynamics. The stress-energy tensor of a heavy quark moving through a strongly coupled N = 4 supersymmetric Yang-Mills plasma is evaluated using gauge/gravity duality. The accuracy with which the resulting wake, in position space, is reproduced by hydrodynamics is examined. Remarkable agreement is found between hydrodynamics and the complete result down to distances less than 2/ T away from the quark. We also compute the penetration depth of a light quark moving through a N = 4 supersymmetric Yang-Mills plasma using a combination of analytic and numerical techniques. We find that the maximum distance a quark with energy E can travel through a plasma is given by Dxmax E= C/T E/Tl 1/3 with C ≈ 0.5. For the study of dynamics far-from-equilibrium, we consider the creation and evolution of boost invariant anisotropic, strongly coupled conformal plasma. In the dual gravitational description, this corresponds to horizon formation in a geometry driven to be anisotropic by a time-dependent change in boundary conditions.
CMS Collaboration
2013-01-01
The recent CMS measurement of the inclusive jet cross section at 7~TeV extends the accessible phase space in jet transverse momentum up to 2 TeV and ranges up to 2.5 in absolute jet rapidity. At the same time the experimental uncertainties are smaller than in previous publications such that these data constrain the parton distribution functions of the proton, notably for the gluon at high fractions of the proton momentum, and provide valuable input to determine the strong coupling at high momentum scales. The impact on the extraction of the parton distribution functions is investigated. Using predictions from theory at next-to-leading order, complemented with electroweak corrections, the strong coupling constant is determined from the inclusive jet cross section to be $\\alpha_S(M_Z) = 0.1185 \\pm 0.0019\\,\\mathrm{(exp.)} \\pm 0.0028\\,\\mathrm{(\\mathrm{PDF})} \\pm 0.0004\\,\\mathrm{(\\mathrm{NP})} ^{+0.0055}_{-0.0022}\\,\\mathrm{(\\mathrm{scale})}$, which is in agreement with the world average.
Shang, Jingwei; Yamashita, Toru; Zhai, Yun; Nakano, Yumiko; Morihara, Ryuta; Fukui, Yusuke; Hishikawa, Nozomi; Ohta, Yasuyuki; Abe, Koji
2016-03-05
Although chronic cerebral hypoperfusion (CCH) may affect Alzheimer's disease (AD) pathogenesis, the mechanism remains elusive. In the present study, we investigated the role of CCH on an AD mouse model in neurovascular unit, cerebrovascular remodeling, and neurovascular trophic coupling. Moreover, examined protective effect of galantamine. Alzheimer's disease transgenic mice (APP23) were subjected to bilateral common carotid arteries stenosis with ameroid constrictors for slowly progressive cerebral hypoperfusion. CCH exacerbated neuronal loss and decrease of α7 subunit of nicotinic acetylcholine receptors (α7-nAChRs) expression in hippocampus and thalamus at 12 months. Meanwhile, CCH greatly induced advanced glycation end products expression, and blood-brain barrier leakage through observing IgG and MMP9 expressions. Furthermore, a significant number of dramatic enlarged cerebral vessels with remodeling, BDNF/TrkB decreased in neurovascular trophic coupling. The present study demonstrated that CCH strongly enhanced primary AD pathology including neurodegeneration, neurovascular unit disruption, cerebrovascular remodeling and neurovascular trophic coupling damage in AD mice, and that galantamine treatment greatly ameliorated such neuropathologic abnormalities.
Watanabe, Norihiro; Blucher, Guido; Cacace, Mauro; Kolditz, Olaf
2016-04-01
A robust and computationally efficient solution is important for 3D modelling of EGS reservoirs. This is particularly the case when the reservoir model includes hydraulic conduits such as induced or natural fractures, fault zones, and wellbore open-hole sections. The existence of such hydraulic conduits results in heterogeneous flow fields and in a strengthened coupling between fluid flow and heat transport processes via temperature dependent fluid properties (e.g. density and viscosity). A commonly employed partitioned solution (or operator-splitting solution) may not robustly work for such strongly coupled problems its applicability being limited by small time step sizes (e.g. 5-10 days) whereas the processes have to be simulated for 10-100 years. To overcome this limitation, an alternative approach is desired which can guarantee a robust solution of the coupled problem with minor constraints on time step sizes. In this work, we present a Newton-Raphson based monolithic coupling approach implemented in the OpenGeoSys simulator (OGS) combined with the Portable, Extensible Toolkit for Scientific Computation (PETSc) library. The PETSc library is used for both linear and nonlinear solvers as well as MPI-based parallel computations. The suggested method has been tested by application to the 3D reservoir site of Groß Schönebeck, in northern Germany. Results show that the exact Newton-Raphson approach can also be limited to small time step sizes (e.g. one day) due to slight oscillations in the temperature field. The usage of a line search technique and modification of the Jacobian matrix were necessary to achieve robust convergence of the nonlinear solution. For the studied example, the proposed monolithic approach worked even with a very large time step size of 3.5 years.
Myasnikova, A. E.; Zhileeva, E. A.; Moseykin, D. V.
2018-03-01
An approach to considering systems with a high concentration of correlated carriers and strong long-range electron–phonon interaction and to calculating the high-energy part of the angle-resolved photoemission spectroscopy (ARPES) spectra of such systems is suggested. Joint relaxation of strongly coupled fields—a field of correlated electrons and phonon field—after photoemission is studied to clarify the nature of characteristic features observed in the high-energy part of the ARPES spectra of cuprate superconductors. Such relaxation occurs in systems with strong predominantly long-range electron–phonon interaction at sufficiently high carrier concentration due to the coexistence of autolocalized and delocalized carriers. A simple method to calculate analytically a high-energy part of the ARPES spectrum arising is proposed. It takes advantage of using the coherent states basis for the phonon field in the polaron and bipolaron states. The approach suggested yields all the high-energy spectral features like broad Gaussian band and regions of ‘vertical dispersion’ being in good quantitative agreement with the experiments on cuprates at any doping with both types of carriers. Demonstrated coexistence of autolocalized and delocalized carriers in superconducting cuprates changes the idea about their ground state above the superconducting transition temperature that is important for understanding transport and magnetic properties. High density of large-radius autolocalized carriers revealed may be a key to the explanation of charge ordering in doped cuprates.
Aktas, A.; Andreev, V.; Anthonis, T.; Antunovic, B.; Aplin, S.; Asmone, A.; Astvatsatourov, A.; Backovic, S.; Baghdasaryan, A.; Baranov, P.; Barrelet, E.; Bartel, W.; Baudrand, S.; Beckingham, M.; Begzsuren, K.; Behnke, O.; Behrendt, O.; Belousov, A.; Berger, N.; Bizot, J.C.; Boenig, M.-O.; Boudry, V.; Bozovic-Jelisavcic, I.; Bracinik, J.; Brandt, G.; Brinkmann, M.; Brisson, V.; Bruncko, D.; Busser, F.W.; Bunyatyan, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A.J.; Cantun Avila, K.B.; Cassol-Brunner, F.; Cerny, K.; Cerny, V.; Chekelian, V.; Cholewa, A.; Contreras, J.G.; Coughlan, J.A.; Cozzika, G.; Cvach, J.; Dainton, J.B.; Daum, K.; Deak, M.; de Boer, Y.; Delcourt, B.; Del Degan, M.; Delvax, J.; De Roeck, A.; De Wolf, E.A.; Diaconu, C.; Dodonov, V.; Dubak, A.; Eckerlin, Guenter; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Eliseev, A.; Elsen, E.; Essenov, S.; Falkiewicz, A.; Faulkner, P.J.W.; Favart, L.; Fedotov, A.; Felst, R.; Feltesse, J.; Ferencei, J.; Finke, L.; Fleischer, M.; Fomenko, A.; Franke, G.; Frisson, T.; Gabathuler, E.; Gayler, J.; Ghazaryan, Samvel; Ginzburgskaya, S.; Glazov, A.; Glushkov, I.; Goerlich, L.; Goettlich, M.; Gogitidze, N.; Gorbounov, S.; Gouzevitch, M.; Grab, C.; Greenshaw, T.; Grell, B.R.; Grindhammer, G.; Habib, S.; Haidt, D.; Hansson, M.; Heinzelmann, G.; Helebrant, C.; Henderson, R.C.W.; Henschel, H.; Herrera, G.; Hildebrandt, M.; Hiller, K.H.; Hoffmann, D.; Horisberger, R.; Hovhannisyan, A.; Hreus, T.; Jacquet, M.; Janssen, M.E.; Janssen, X.; Jemanov, V.; Jonsson, L.; Johnson, D.P.; Jung, Andreas Werner; Jung, H.; Kapichine, M.; Katzy, J.; Kenyon, I.R.; Kiesling, Christian M.; Klein, M.; Kleinwort, C.; Klimkovich, T.; Kluge, T.; Knutsson, A.; Korbel, V.; Kostka, P.; Kraemer, M.; Krastev, K.; Kretzschmar, J.; Kropivnitskaya, A.; Kruger, K.; Landon, M.P.J.; Lange, W.; Lastovicka-Medin, G.; Laycock, P.; Lebedev, A.; Leibenguth, G.; Lendermann, V.; Levonian, S.; Li, G.; Lindfeld, L.; Lipka, K.; Liptaj, A.; List, B.; List, J.; Loktionova, N.; Lopez-Fernandez, R.; Lubimov, V.; Lucaci-Timoce, A.-I.; Lytkin, L.; Makankine, A.; Malinovski, E.; Marage, P.; Marti, Ll.; Martisikova, M.; Martyn, H.-U.; Maxfield, S.J.; Mehta, A.; Meier, K.; Meyer, A.B.; Meyer, H.; Meyer, J.; Michels, V.; Mikocki, S.; Milcewicz-Mika, I.; Mohamed, A.; Moreau, F.; Morozov, A.; Morris, J.V.; Mozer, Matthias Ulrich; Muller, K.; Murin, P.; Nankov, K.; Naroska, B.; Naumann, Th.; Newman, Paul R.; Niebuhr, C.; Nikiforov, A.; Nowak, G.; Nowak, K.; Nozicka, M.; Oganezov, R.; Olivier, B.; Olsson, J.E.; Osman, S.; Ozerov, D.; Palichik, V.; Panagoulias, I.; Pandurovic, M.; Papadopoulou, Th.; Pascaud, C.; Patel, G.D.; Peng, H.; Perez, E.; Perez-Astudillo, D.; Perieanu, A.; Petrukhin, A.; Picuric, I.; Piec, S.; Pitzl, D.; Placakyte, R.; Polifka, R.; Povh, B.; Preda, T.; Prideaux, P.; Radescu, V.; Rahmat, A.J.; Raicevic, N.; Ravdandorj, T.; Reimer, P.; Risler, C.; Rizvi, E.; Robmann, P.; Roland, B.; Roosen, R.; Rostovtsev, A.; Rurikova, Z.; Rusakov, S.; Salvaire, F.; Sankey, D.P.C.; Sauter, M.; Sauvan, E.; Schmidt, S.; Schmitt, S.; Schmitz, C.; Schoeffel, L.; Schoning, A.; Schultz-Coulon, H.-C.; Sefkow, F.; Shaw-West, R.N.; Sheviakov, I.; Shtarkov, L.N.; Sloan, T.; Smiljanic, Ivan; Smirnov, P.; Soloviev, Y.; South, D.; Spaskov, V.; Specka, Arnd E.; Staykova, Z.; Steder, M.; Stella, B.; Stiewe, J.; Straumann, U.; Sunar, D.; Sykora, T.; Tchoulakov, V.; Thompson, G.; Thompson, P.D.; Toll, T.; Tomasz, F.; Tran, T.H.; Traynor, D.; Trinh, T.N.; Truol, P.; Tsakov, I.; Tseepeldorj, B.; Tsipolitis, G.; Tsurin, I.; Turnau, J.; Tzamariudaki, E.; Urban, K.; Utkin, D.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vargas Trevino, A.; Vazdik, Y.; Vinokurova, S.; Volchinski, V.; Weber, G.; Weber, R.; Wegener, D.; Werner, C.; Wessels, M.; Wissing, Ch.; Wolf, R.; Wunsch, E.; Xella, S.; Yan, W.; Yeganov, V.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zhelezov, A.; Zhokin, A.; Zhu, Y.C.; Zimmermann, T.; Zohrabyan, H.; Zomer, F.
2007-01-01
Inclusive jet production is studied in neutral current deep-inelastic positron-proton scattering at large four momentum transfer squared Q^2>150 GeV^2 with the H1 detector at HERA. Single and double differential inclusive jet cross sections are measured as a function of Q^2 and of the transverse energy E_T of the jets in the Breit frame. The measurements are found to be well described by calculations at next-to-leading order in perturbative QCD. The running of the strong coupling is demonstrated and the value of alpha_s(M_Z) is determined. The ratio of the inclusive jet cross section to the inclusive neutral current cross section is also measured and used to extract a precise value for alpha_s(M_Z)=0.1193+/-0.0014(exp.)^{+0.0047}_{-0.0030}(th.)+/-0.0016(pdf).
Abbiendi, G.; Akesson, P.F.; Alexander, G.; Anagnostou, G.; Anderson, K.J.; Asai, S.; Axen, D.; Bailey, I.; Barberio, E.; Barillari, T.; Barlow, R.J.; Batley, R.J.; Bechtle, P.; Behnke, T.; Bell, Kenneth Watson; Bell, P.J.; Bella, G.; Bellerive, A.; Benelli, G.; Bethke, S.; Biebel, O.; Boeriu, O.; Bock, P.; Boutemeur, M.; Braibant, S.; Brown, Robert M.; Burckhart, H.J.; Campana, S.; Capiluppi, P.; Carnegie, R.K.; Carter, A.A.; Carter, J.R.; Chang, C.Y.; Charlton, D.G.; Ciocca, C.; Csilling, A.; Cuffiani, M.; Dado, S.; De Roeck, A.; De Wolf, E.A.; Desch, K.; Dienes, B.; Dubbert, J.; Duchovni, E.; Duckeck, G.; Duerdoth, I.P.; Etzion, E.; Fabbri, F.; Ferrari, P.; Fiedler, F.; Fleck, I.; Ford, M.; Frey, A.; Gagnon, P.; Gary, John William; Geich-Gimbel, C.; Giacomelli, G.; Giacomelli, P.; Giunta, Marina; Goldberg, J.; Gross, E.; Grunhaus, J.; Gruwe, M.; Gunther, P.O.; Gupta, A.; Hajdu, C.; Hamann, M.; Hanson, G.G.; Harel, A.; Hauschild, M.; Hawkes, C.M.; Hawkings, R.; Hemingway, R.J.; Herten, G.; Heuer, R.D.; Hill, J.C.; Horvath, D.; Igo-Kemenes, P.; Ishii, K.; Jeremie, H.; Jovanovic, P.; Junk, T.R.; Kanzaki, J.; Karlen, D.; Kawagoe, K.; Kawamoto, T.; Keeler, R.K.; Kellogg, R.G.; Kennedy, B.W.; Kluth, S.; Kobayashi, T.; Kobel, M.; Komamiya, S.; Kramer, T.; Krasznahorkay, A.; Krieger, P.; von Krogh, J.; Kuhl, T.; Kupper, M.; Lafferty, G.D.; Landsman, H.; Lanske, D.; Lellouch, D.; Lettso, J.; Levinson, L.; Lillich, J.; Lloyd, S.L.; Loebinger, F.K.; Lu, J.; Ludwig, A.; Ludwig, J.; Mader, W.; Marcellini, S.; Martin, A.J.; Mashimo, T.; Mattig, Peter; McKenna, J.; McPherson, R.A.; Meijers, F.; Menges, W.; Merritt, F.S.; Mes, H.; Meyer, Niels T.; Michelini, A.; Mihara, S.; Mikenberg, G.; Miller, D.J.; Mohr, W.; Mori, T.; Mutter, A.; Nagai, K.; Nakamura, I.; Nanjo, H.; Neal, H.A.; Nisius, R.; O'Neale, S.W.; Oh, A.; Oreglia, M.J.; Orito, S.; Pahl, C.; Pasztor, G.; Pater, J.R.; Pilcher, J.E.; Pinfold, J.; Plane, David E.; Pooth, O.; Przybycien, M.; Quadt, A.; Rabbertz, K.; Rembser, C.; Renkel, P.; Roney, J.M.; Rossi, A.M.; Rozen, Y.; Runge, K.; Sachs, K.; Saeki, T.; Sarkisyan, E.K.G.; Schaile, A.D.; Schaile, O.; Scharff-Hansen, P.; Schieck, J.; Schorner-Sadenius, T.; Schroder, Matthias; Schumacher, M.; Seuster, R.; Shears, T.G.; Shen, B.C.; Sherwood, P.; Skuja, A.; Smith, A.M.; Sobie, R.; Soldner-Rembold, S.; Spano, F.; Stahl, A.; Strom, David M.; Strohmer, R.; Tarem, S.; Tasevsky, M.; Teuscher, R.; Thomson, M.A.; Torrence, E.; Toya, D.; Tran, P.; Trigger, I.; Trocsanyi, Z.; Tsur, E.; Turner-Watson, M.F.; Ueda, I.; Ujvari, B.; Vollmer, C.F.; Vannerem, P.; Vertesi, R.; Verzocchi, M.; Voss, H.; Vossebeld, J.; Ward, C.P.; Ward, D.R.; Watkins, P.M.; Watson, A.T.; Watson, N.K.; Wells, P.S.; Wengler, T.; Wermes, N.; Wilson, G.W.; Wilson, J.A.; Wolf, G.; Wyatt, T.R.; Yamashita, S.; Zer-Zion, D.; Zivkovic, Lidija
2006-01-01
Data from e+e- annihilation into hadrons at centre-of-mass energies between 91 GeV and 209 GeV collected with the OPAL detector at LEP, are used to study the four-jet rate as a function of the Durham algorithm resolution parameter ycut. The four-jet rate is compared to next-to-leading order calculations that include the resummation of large logarithms. The strong coupling measured from the four-jet rate is alphas(Mz0)= 0.1182+-0.0003(stat.)+-0.0015(exp.)+-0.0011(had.)+-0.0012(scale)+-0.0013(mass) in agreement with the world average. Next-to-leading order fits to the D-parameter and thrust minor event-shape observables are also performed for the first time. We find consistent results, but with significantly larger theoretical uncertainties.
Strongly coupled rotational band in ${}^{33}\mathrm{Mg}$
Energy Technology Data Exchange (ETDEWEB)
Richard, A. L. [Ohio Univ., Athens, OH (United States). Inst. for Nuclear and Particle Physics; Crawford, H. L. [Ohio Univ., Athens, OH (United States). Inst. for Nuclear and Particle Physics; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Nuclear Science Div.; Fallon, P. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Nuclear Science Div.; Macchiavelli, A. O. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Nuclear Science Div.; Bader, V. M. [Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab; Michigan State Univ., East Lansing, MI (United States). Dept. of Physics and Astronomy; Bazin, D. [Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.; Bowry, M. [Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab; Campbell, C. M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Nuclear Science Div.; Carpenter, M. P. [Argonne National Lab. (ANL), Argonne, IL (United States). Physics Div.; Clark, R. M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Nuclear Science Div.; Cromaz, M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Nuclear Science Div.; Gade, A. [Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab; Michigan State Univ., East Lansing, MI (United States). Dept. of Physics and Astronomy; Ideguchi, E. [Osaka Univ. (Japan). RCNP; Iwasaki, H. [Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab; Michigan State Univ., East Lansing, MI (United States). Dept. of Physics and Astronomy; Jones, M. D. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Nuclear Science Div.; Langer, C. [Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab; Lee, I. Y. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Nuclear Science Div.; Loelius, C. [Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab; Michigan State Univ., East Lansing, MI (United States). Dept. of Physics and Astronomy; Lunderberg, E. [Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab; Michigan State Univ., East Lansing, MI (United States). Dept. of Physics and Astronomy; Morse, C. [Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab; Michigan State Univ., East Lansing, MI (United States). Dept. of Physics and Astronomy; Rissanen, J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Nuclear Science Div.; Salathe, M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Nuclear Science Div.; Smalley, D. [Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab; Stroberg, S. R. [Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab; Michigan State Univ., East Lansing, MI (United States). Dept. of Physics and Astronomy; Weisshaar, D. [Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab; Whitmore, K. [Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab; Michigan State Univ., East Lansing, MI (United States). Dept. of Physics and Astronomy; Wiens, A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Nuclear Science Div.; Williams, S. J. [Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab; Wimmer, K. [Univ. of Tokyo (Japan). Dept. of Physics; Yamamato, T. [Osaka Univ. (Japan). RCNP
2017-07-01
The “island of inversion” at N≈20 for the neon, sodium, and magnesium isotopes has long been an area of interest both experimentally and theoretically due to the subtle competition between 0p-0h and np-nh configurations leading to deformed shapes. However, the presence of rotational band structures, which are fingerprints of deformed shapes, have only recently been observed in this region. In this work, we report on a measurement of the low-lying level structure of Mg33 populated by a two-stage projectile fragmentation reaction and studied with the Gamma Ray Energy Tracking In-Beam Nuclear Array (GRETINA). The experimental level energies, ground-state magnetic moment, intrinsic quadrupole moment, and γ-ray intensities show good agreement with the strong-coupling limit of a rotational model.
Strongly coupled rotational band in ${}^{33}\mathrm{Mg}$
Energy Technology Data Exchange (ETDEWEB)
Richard, A. L.; Crawford, H. L.; Fallon, P.; Macchiavelli, A. O.; Bader, V. M.; Bazin, D.; Bowry, M.; Campbell, C. M.; Carpenter, M. P.; Clark, R. M.; Cromaz, M.; Gade, A.; Ideguchi, E.; Iwasaki, H.; Jones, M. D.; Langer, C.; Lee, I. Y.; Loelius, C.; Lunderberg, E.; Morse, C.; Rissanen, J.; Salathe, M.; Smalley, D.; Stroberg, S. R.; Weisshaar, D.; Whitmore, K.; Wiens, A.; Williams, S. J.; Wimmer, K.; Yamamato, T.
2017-07-01
The “Island of Inversion” at N~20 for the neon, sodium, and magnesium isotopes has long been an area of interest both experimentally and theoretically due to the subtle competition between 0p-0h and np-nh configurations leading to deformed shapes. However, the presence of rotational band structures, which are fingerprints of deformed shapes, have only recently been observed in this region. In this work, we report on a measurement of the low-lying level structure of 33Mg populated by a two-stage projectile fragmentation reaction and studied with GRETINA. The experimental level energies, ground state magnetic moment, intrinsic quadrupole moment, and γ-ray intensities show good agreement with the strong-coupling limit of a rotational model.
Gor'kov, Lev P.
2012-04-01
We consider a single band of conduction electrons interacting with displacements of the transitional ions. In the classical regime strong enough coupling transforms the harmonic elastic energy for an ion to the one of the well with two deep minima, so that the system is described in terms of Ising spins. Intersite interactions order spins at lower temperatures. Extension to the quantum regime is discussed. Below the charge density wave (CDW) transition the energy spectrum of electrons remains metallic because the structural vector Q and the Fermi surface sizes are not related. Large values of the CDW gap seen in the tunneling experiments correspond to the energy of the minima in the electron-ion two-well complex. The gap is defined through the density of states inside the electronic bands below the CDW transition. We focus mainly on electronic properties of transition-metal dichalcogenides.
Vafaee, A.; Khorramian, A.
2017-11-01
In this QCD analysis, we investigate the impact of recent measurements of heavy-flavor charm and beauty cross sections data sets on the simultaneous determination of Parton Distribution Functions (PDFs) and the strong coupling, αs(M2Z). We perform three different fits based on Variable-Flavour Number Scheme (VFNS) at the Leading Order (LO) and Next-to-Leading Order (NLO) and choose the full HERA run I and II combined data as a new measurement of inclusive Deep Inelastic Scattering (DIS) cross sections for our base data set. We show that including charm and beauty cross sections data reduces the uncertainty of gluon distribution and improves the fit quality up to 4.1% from leading order to next-to-leading order and up to 1.7% for only NLO without and with beauty and charm data contributions.
Llorente Merino, Javier; The ATLAS collaboration
2018-01-01
A measurement of transverse energy--energy correlations and its asymmetry in $pp$ collisions recorded by the ATLAS detector at the LHC at $\\sqrt{s} = 8$ TeV is presented. The results are intepreted as a precision test of Quantum Chromodynamics, used to determine the strong coupling constant $\\alpha_s(m_Z)$ and to test asymptotic freedom up to scales close to 1 TeV. A global fit to the transverse energy--energy correlation distributions yields $\\alpha_{\\mathrm{s}}(m_Z) = 0.1162 \\pm 0.0011 \\mbox{ (exp.)}^{+0.0084}_{-0.0070} \\mbox{ (theo.)}$, while a global fit to the asymmetry distributions yields a value of $\\alpha_{\\mathrm{s}}(m_Z) = 0.1196 \\pm 0.0013 \\mbox{ (exp.)}^{+0.0075}_{-0.0045} \\mbox{ (theo.)}$.
Scuri, Giovanni; Zhou, You; High, Alexander; Dibos, Alan; de Greve, Kristiaan; Polking, Mark; Juaregui, Luis; Wild, Dominik; Joe, Andrew; Pistunova, Kateryna; Lukin, Mikhail; Kim, Philip; Park, Hongkun
Two-dimensional transition-metal dichalcogenide (TMDC) monolayers exhibit direct bandgap excitons with large binding energy. The optical response of TMDCs is electrically tunable over a broad wavelength range, making these 2D materials promising candidates for optoelectronic devices. In this work, we enhance exciton-plasmon coupling by embedding a single layer of tungsten diselenide (WSe2) into a plasmonic crystal cavity, which confines surface plasmon polaritons in an analogous manner to photonic crystal cavities. We observe strong light-matter interactions and the formation of microcavity polaritons when the cavity mode is on resonance with the exciton absorption in WSe2. Using the electrostatically controllable response of such excitons, we also demonstrate tunable vacuum Rabi splitting in such a system.
Bruch, Anton; Lewenkopf, Caio; von Oppen, Felix
2018-03-01
We develop a Landauer-Büttiker theory of entropy evolution in time-dependent, strongly coupled electron systems. The formalism naturally avoids the problem of the system-bath distinction by defining the entropy current in the attached leads. This current can then be used to infer changes of the entropy of the system which we refer to as the inside-outside duality. We carry out this program in an adiabatic expansion up to first order beyond the quasistatic limit. When combined with particle and energy currents, as well as the work required to change an external potential, our formalism provides a full thermodynamic description, applicable to arbitrary noninteracting electron systems in contact with reservoirs. This provides a clear understanding of the relation between heat and entropy currents generated by time-dependent potentials and their connection to the occurring dissipation.
Sieber, Georg; Rabbertz, Klaus
This thesis presents the sensitivity study of PDFs and $\\alpha_\\mathrm{S}$ to the inclusive jet cross section at a center-of-mass energy of $\\sqrt{s}$ = 7 TeV. The data corresponds to an integrated luminosity of 5 fb$^{-1}$ collected with the CMS detector in 2011. Next-to-leading order calculations have been compared to the measurement and found agreement within uncertainties. The PDF sensitivity has been studied using the HERAFitter framework. It was found that the inclusive jet cross section constrains the quark and gluon PDFs in the high-$x$ region and reduces the PDF uncertainties. Furthermore the strong coupling has been extracted using fixed global PDF sets.
International Nuclear Information System (INIS)
Behrend, H.J.; Chen, C.; Fenner, H.; Schachter, M.J.; Schroeder, V.; Sindt, H.; D'Agostini, G.; Apel, W.D.; Banerjee, S.; Bodenkamp, J.; Chrobaczek, D.; Engler, J.; Fluegge, G.; Fries, D.C.; Fues, W.; Gamerdinger, K.; Hopp, G.; Kuester, H.; Mueller, H.; Randoll, H.; Schmidt, G.; Schneider, H.; Boer, W. de; Buschhorn, G.; Grindhammer, G.; Grosse-Wiesmann, P.; Gunderson, B.; Kiesling, C.; Kotthaus, R.; Kruse, U.; Lierl, H.; Lueers, D.; Oberlack, H.; Schacht, P.; Colas, P.; Cordier, A.; Davier, M.; Fournier, D.; Grivaz, J.F.; Haissinski, J.; Journe, V.; Klarsfeld, A.; Laplanche, F.; Le Diberder, F.; Mallik, U.; Veillet, J.J.; Field, J.H.; George, R.; Goldberg, M.; Grossetete, B.; Hamon, O.; Kapusta, F.; Kovacs, F.; London, G.; Poggioli, L.; Rivoal, M.; Aleksan, R.; Bouchez, J.; Carnesecchi, G.; Cozzika, G.; Ducros, Y.; Gaidot, A.; Jadach, S.; Lavagne, Y.; Pamela, J.; Pansart, J.P.; Pierre, F.
1983-01-01
Hadronic events obtained with the CELLO detector at PETRA were compared with first-order QCD predictions using two different models for the fragmentation of quarks and gluons, the Hoyer model and the Lund model. Both models are in reasonable agreement with the data, although they do not completely reproduce the details of many distributions. Several methods have been applied to determine the strong coupling constant αsub(s). Although within one model the value of αsub(s) varies by 20% among the different methods, the values determined using the Lund model are 30% or more larger (depending on the method used) than the values determined with the Hoyer model. Our results using the Hoyer model are in agreement with previous results based on this approach. (orig.)
International Nuclear Information System (INIS)
Meevasana, W; Chen, C-C; He, R H; Mo, S-K; Shen, Z-X; Zhou, X J; Moritz, B; Lu, D H; Moore, R G; Devereaux, T P; Fujimori, S-I; Baumberger, F; Van der Marel, D; Nagaosa, N; Zaanen, J
2010-01-01
Much progress has been made recently in the study of the effects of electron-phonon (el-ph) coupling in doped insulators using angle-resolved photoemission (ARPES), yielding evidence for the dominant role of el-ph interactions in underdoped cuprates. As these studies have been limited to doped Mott insulators, the important question arises as to how this compares with doped band insulators where similar el-ph couplings should be at work. The archetypical case is that of perovskite SrTiO 3 (STO), well known for its giant dielectric constant of 10 000 at low temperatures, exceeding that of La 2 CuO 4 by a factor of 500. Based on this fact, it has been suggested that doped STO should be the archetypical bipolaron superconductor. Here we report an ARPES study from high-quality surfaces of lightly doped STO. In comparison to lightly doped Mott insulators, we find the signatures of only moderate el-ph coupling; a dispersion anomaly associated with the low-frequency optical phonon with a λ ' ∼0.3 and an overall bandwidth renormalization suggesting an overall λ ' ∼0.7 coming from the higher frequency phonons. Furthermore, we find no clear signatures of the large pseudogap or small-polaron phenomena. These findings demonstrate that a large dielectric constant itself is not a good indicator of el-ph coupling and highlight the unusually strong effects of the el-ph coupling in doped Mott insulators.
Baule, A; Evans, R M L; Olmsted, P D
2006-12-01
We revisit the paradigm of an ideal gas under isothermal conditions. A moving piston performs work on an ideal gas in a container that is strongly coupled to a heat reservoir. The thermal coupling is modeled by stochastic scattering at the boundaries. In contrast to recent studies of an adiabatic ideal gas with a piston [R.C. Lua and A.Y. Grosberg, J. Phys. Chem. B 109, 6805 (2005); I. Bena, Europhys. Lett. 71, 879 (2005)], the container and piston stay in contact with the heat bath during the work process. Under this condition the heat reservoir as well as the system depend on the work parameter lambda and microscopic reversibility is broken for a moving piston. Our model is thus not included in the class of systems for which the nonequilibrium work theorem has been derived rigorously either by Hamiltonian [C. Jarzynski, J. Stat. Mech. (2004) P09005] or stochastic methods [G.E. Crooks, J. Stat. Phys. 90, 1481 (1998)]. Nevertheless the validity of the nonequilibrium work theorem is confirmed both numerically for a wide range of parameter values and analytically in the limit of a very fast moving piston, i.e., in the far nonequilibrium regime.
A strongly coupled open system with a non-linear bath: fluctuation-dissipation and Langevin dynamics
Bhadra, Chitrak
2018-03-01
The study of Langevin dynamics and fluctuation-dissipation relation (FDR) for a generic probe system (represented by a mass M ), bilinearly coupled to a bath of harmonic oscillators, has been a standard paradigm for the microscopic theory of stochastic processes for several decades. The question that we probe in this paper is, how robust the structure of the classical FDR is, when one replaces the harmonic bath by an anharmonic one in the limit of strong system-bath coupling? Such a picture carries the signature of the probe system in the zeroth order through a nonlocal time kernel. We observe that the two-time noise correlations hold a rich structure from which the usual FDR emerges only in the leading order of perturbation. Beyond this order, multiple time scales and nontrivial dependence on the temperature starts to manifest. These new aspects conspire to break the time-translational invariance of the noise-correlations. Several other interesting features show up and we discuss them methodically through rigorous calculations order-by-order in perturbation. This formalistic derivation along with a specific example of non-linearity can be easily applied to a huge range of processes and statistical observables that fall under the purview of a system-reservoir theory.
Molecular quantum magnetism with strong spin-orbit coupling in inorganic solid Ba3Yb2Zn5O11
Park, Sang-Youn; Ji, Sungdae; Park, Jae-Hoon; Do, Seunghwan; Choi, Kwang-Yong; Jang, Dongjin; Schmidt, Burkhard; Brando, Manuel; Butch, Nicholas
The molecular magnet, assembly of finite number of spins which are isolated from environment, is a model system to study the quantum information process such as the qubit or spintronic devices. In past decades, the molecular magnet has been mostly realized in organic material, however, it has difficulty synthesizing materials or controlling their properties, meanwhile tremendous endeavors to search inorganic molecular magnet are continuing. Here, we propose Ba3Yb2Zn5O11 as a candidate of inorganic molecular magnet. This material consists of an alternating 3D-array of small and large tetrahedron containing antiferromagnetically coupled four pseudospin-1/2 Yb ions, and magnetic properties are described by an isolated tetrahedron without long-range magnetic ordering. Inelastic neutron scattering measurement with external magnetic field reveals that extraordinarily huge Dzyaloshinsky-Moriya (DM) interaction originating from strong spin-orbit coupling in Yb isospin is the key to explain energy level of tetrahedron in addition to Heisenberg exchange interaction and Zeeman effect. Magnetization measurement shows the Landau-Zener transition between avoided crossing levels caused by DM interaction.
Gupta, Akanksha; Ganesh, Rajaraman; Joy, Ashwin
2018-01-01
In this paper, we perform comparative studies of compressible Kolmogorov flow in the two-dimensional strongly coupled dusty plasma by means of atomistic or molecular dynamics (MD) and continuum or computational fluid dynamics (CFD) methods. Recently, using MD simulation, generation of molecular shear heat at the atomistic level is shown to reduce the average coupling strength of the system and destruct the vortical structures. To suppress the molecular heat, a novel method of a thermostat, namely, the configurational thermostat is introduced by which the microscale heat generated by the shear flow has shown to be thermostatted out efficiently without compromising the large scale vortex dynamics. While using a configurational thermostat, it has been found that the growth rate obtained from both the studies is the same with the marginal difference. To make the comparison with the continuum fluid model, we perform the same study using the generalised hydrodynamic model, wherein molecular shear heating phenomena is completely absent, however, viscous dissipation is there at the macroscale level. For this purpose, an Advanced Generalised SPECTral Code has been developed to study the linear and nonlinear aspects of the Kolmogorov flow in the incompressible and compressible limit for viscoelastic fluids. All the phenomenological parameters used in CFD simulations have been calculated from MD simulations. Code is benchmarked against the eigen value solver in the linear regime. Linear growth-rates calculated from the phenomenological fluid model is found to be close to that obtained from MD simulation for the same set of input parameters. The transition from laminar to turbulent flow has been found at a critical value of Reynolds number Rc in both the macroscopic (CFD) and microscopic (MD) simulation. Rc in MD is smaller than the one obtained by CFD simulation. In the nonlinear regime of CFD, the mode becomes unstable and vortex formation happens earlier than in MD. The
Sun, Zheng; Xu, Yuan-Ping; Li, Sheng; George, Thomas F
2011-02-10
Through combining the electron transition process and dipole moment evolution as well as electron-phonon coupling, molecular dynamics calculations show that the radiative decay of singlet excitons in a conjugated polymer, such as a polymer light-emitting diode (PLED), is largely determined by the evolution of the dipole moment. Without an electric field, the decay life of a singlet exciton is about 1 ns. Once an electric field is applied and exceeds a critical value, with electron-phonon coupling, the original lattice structure evolves into two new localized lattice distortions, consistent with the experimental results. Owing to the new lattice structure and self-trapping, the dipole moment rapidly decreases to zero within 5 fs, eliminating the radiative decay of the singlet exciton.
Energy Technology Data Exchange (ETDEWEB)
Capecelatro, Jesse, E-mail: jcaps@illinois.edu [Coordinated Science Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801-2307 (United States); Desjardins, Olivier [Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York 14853 (United States); Fox, Rodney O. [Department of Chemical and Biological Engineering, Center for Multiphase Flow Research, Iowa State University, Ames, Iowa 50011-2230 (United States); Laboratoire EM2C, CNRS, CentraleSupélec, Université Paris-Saclay, Grande Vois des Vignes, 92295 Chatenay Malabry (France)
2016-03-15
Simulations of strongly coupled (i.e., high-mass-loading) fluid-particle flows in vertical channels are performed with the purpose of understanding the fundamental physics of wall-bounded multiphase turbulence. The exact Reynolds-averaged (RA) equations for high-mass-loading suspensions are presented, and the unclosed terms that are retained in the context of fully developed channel flow are evaluated in an Eulerian–Lagrangian (EL) framework for the first time. A key distinction between the RA formulation presented in the current work and previous derivations of multiphase turbulence models is the partitioning of the particle velocity fluctuations into spatially correlated and uncorrelated components, used to define the components of the particle-phase turbulent kinetic energy (TKE) and granular temperature, respectively. The adaptive spatial filtering technique developed in our previous work for homogeneous flows [J. Capecelatro, O. Desjardins, and R. O. Fox, “Numerical study of collisional particle dynamics in cluster-induced turbulence,” J. Fluid Mech. 747, R2 (2014)] is shown to accurately partition the particle velocity fluctuations at all distances from the wall. Strong segregation in the components of granular energy is observed, with the largest values of particle-phase TKE associated with clusters falling near the channel wall, while maximum granular temperature is observed at the center of the channel. The anisotropy of the Reynolds stresses both near the wall and far away is found to be a crucial component for understanding the distribution of the particle-phase volume fraction. In Part II of this paper, results from the EL simulations are used to validate a multiphase Reynolds-stress turbulence model that correctly predicts the wall-normal distribution of the two-phase turbulence statistics.
International Nuclear Information System (INIS)
Swenson, C.A.
1996-01-01
Linear thermal expansivity (α) measurements from 1 to 300 K and heat capacity (C p ) measurements from 1 to 110 K are reported for single crystals of the hexagonal scandium and lutetium metals; the C p data were combined with previous data to obtain smooth representations to 305 K for Lu and 350 K for Sc. The Θ 0 close-quote s (352 and 190 K, respectively, for Sc and Lu) and γ close-quote s (10.38 and 8.30 mJ/molK 2 , respectively for Sc and Lu) are in reasonable agreement with previous data of various kinds. Electronic contributions are much larger for the α close-quote s than for the C p close-quote s, with the large anisotropies of the α close-quote s primarily electronic in origin. The equivalent Debye Θ close-quote s for the lattice C p close-quote s and the Grueneisen parameters Γ for the lattice α close-quote s both show an unexpected T dependence at open-quote open-quote high close-quote close-quote T (T approx-gt Θ 0 /2), which can be associated with the disappearance of spin-fluctuation and electron-phonon enhancements to the electronic properties; this effect has been reported previously for Sc C ν close-quote s by Pleschiutschnig et al. [Phys. Rev. B 44, 6794 (1991)]. While the resulting high-temperature open-quote open-quote bare close-quote close-quote or open-quote open-quote density of states close-quote close-quote γ for Sc, γ b =5.75(25) mJ/molK 2 , is slightly larger than that calculated recently by Goetz and Winter [J. Phys. Condens. Matter 5, 1721 (1993)], the magnitude of the sum (γ spin +γep) agrees well. For Lu, for which no recent calculations exist, γ b =5.50(25) mJ/molK 2 . (Abstract Truncated)
Energy Technology Data Exchange (ETDEWEB)
Swenson, C.A. [Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States)
1996-02-01
Linear thermal expansivity ({alpha}) measurements from 1 to 300 K and heat capacity ({ital C}{sub {ital p}}) measurements from 1 to 110 K are reported for single crystals of the hexagonal scandium and lutetium metals; the {ital C}{sub {ital p}} data were combined with previous data to obtain smooth representations to 305 K for Lu and 350 K for Sc. The {Theta}{sub 0}{close_quote}s (352 and 190 K, respectively, for Sc and Lu) and {gamma}{close_quote}s (10.38 and 8.30 mJ/molK{sup 2}, respectively for Sc and Lu) are in reasonable agreement with previous data of various kinds. Electronic contributions are much larger for the {alpha}{close_quote}s than for the {ital C}{sub {ital p}}{close_quote}s, with the large anisotropies of the {alpha}{close_quote}s primarily electronic in origin. The equivalent Debye {Theta}{close_quote}s for the lattice {ital C}{sub {ital p}}{close_quote}s and the Gr{umlt u}neisen parameters {Gamma} for the lattice {alpha}{close_quote}s both show an unexpected {ital T} dependence at {open_quote}{open_quote}high{close_quote}{close_quote} {ital T} ({ital T}{approx_gt}{Theta}{sub 0}/2), which can be associated with the disappearance of spin-fluctuation and electron-phonon enhancements to the electronic properties; this effect has been reported previously for Sc {ital C}{sub {nu}}{close_quote}s by Pleschiutschnig {ital et} {ital al}. [Phys. Rev. B {bold 44}, 6794 (1991)]. While the resulting high-temperature {open_quote}{open_quote}bare{close_quote}{close_quote} or {open_quote}{open_quote}density of states{close_quote}{close_quote} {gamma} for Sc, {gamma}{sub {ital b}}=5.75(25) mJ/molK{sup 2}, is slightly larger than that calculated recently by G{umlt o}tz and Winter [J. Phys. Condens. Matter {bold 5}, 1721 (1993)], the magnitude of the sum ({gamma}{sub spin}+{gamma}{ital ep}) agrees well. For Lu, for which no recent calculations exist, {gamma}{sub {ital b}}=5.50(25) mJ/molK{sup 2}. (Abstract Truncated)
Sato, T; Tanaka, Y; Nakayama, K; Souma, S; Takahashi, T; Sasaki, S; Ren, Z; Taskin, A A; Segawa, Kouji; Ando, Yoichi
2013-05-17
We have performed angle-resolved photoemission spectroscopy on the strongly spin-orbit coupled low-carrier density superconductor Sn(1-x)In(x)Te (x = 0.045) to elucidate the electronic states relevant to the possible occurrence of topological superconductivity, as recently reported for this compound based on point-contact spectroscopy. The obtained energy-band structure reveals a small holelike Fermi surface centered at the L point of the bulk Brillouin zone, together with a signature of a topological surface state, indicating that this material is a doped topological crystalline insulator characterized by band inversion and mirror symmetry. A comparison of the electronic states with a band-noninverted superconductor possessing a similar Fermi surface structure, Pb(1-x)Tl(x)Te, suggests that the anomalous behavior in the superconducting state of Sn(1-x)In(x)Te is related to the peculiar orbital characteristics of the bulk valence band and/or the presence of a topological surface state.
Measurement of the strong interaction coupling constant αs by jet study in the H1 experiment
International Nuclear Information System (INIS)
Squinabol, F.
1997-01-01
The H1 experiment allows to study hadronic jets produced in deep inelastic lepton (27.5 GeV) scattering off protons (820 GeV). The coupling constant of the strong interaction α s can be extracted from the measurement of the 2-jets rate in the final state. The use of the JADE algorithm is optimal for events with high energy transfer (100-4,000 GeV 2 ), corresponding to the 1994 and 1995 data. The error on α s (M Z 0 2 ) is dominated by the uncertainty from the hadronic energy measurement and the experimental resolution effects on jets. The theoretical error is dominated by the renormalization scale dependence. The final result is (M Z 0 2 ) 0.118 -0.008 +0.008 . This analysis is extended to smaller momentum transfers (25-100 GeV 2 ) using the factorizable K t algorithm, taking the transferred momentum as energy scale of the particle re-clustering. The result α s (M Z 0 2 ) 0.117 -0.008 +0.009 is compatible with the previous one. The precision of the measurement performed in this thesis is 7%. A precision of 4% could be achieved after progresses in the theoretical framework and/or after a significant increase of the luminosity. (author)
Gangolf, Thomas; Blecher, Marius; Bolanos, Simon; Lancia, Livia; Marques, Jean-Raphael; Cerchez, Mirela; Prasad, Rajendra; Aurand, Bastian; Loiseau, Pascal; Fuchs, Julien; Willi, Oswald
2017-10-01
In the ongoing quest for novel techniques to obtain ever higher laser powers, plasma amplification has drawn much attention, benefiting from the fact that a plasma can sustain much higher energy densities than a solid state amplifier. As a plasma process, Stimulated Brillouin Backscattering in the strong coupling regime (sc-SBS) can be used to transfer energy from one laser pulse (pump) to another (seed), by a nonlinear ion oscillation forced by the pump laser. Here, we report on experimental results on amplification by sc-SBS using the ARCTURUS Ti:Sapphire multi-beam laser system at the University of Duesseldorf, Germany. Counter-propagating in a supersonic Hydrogen gas jet target, an ultrashort seed pulse with a pulse duration between 30 and 160 fs and an energy between 1 and 12 mJ was amplified by a high-energy pump pulse (1.7 ps, 700 mJ). For some of the measurements, the gas was pre-ionized with a separate laser pulse (780 fs, 460 mJ). Preliminary analysis shows that the amplification was larger for the longer seed pulses, consistent with theoretical predictions.
Tahir, N A; Shutov, A; Udrea, S; Deutsch, C; Fortov, V E; Gryaznov, V; Hoffmann, Dieter H H; Jacobi, J; Kain, V; Kuster, M; Ni, P; Piriz, A R; Schmidt, R; Spiller, P; Varentsov, D; Zioutas, K
2006-01-01
Detailed theoretical studies have shown that intense heavy-ion beams that will be generated at the future Facility for Antiprotons and Ion Research (FAIR) (Henning 2004 Nucl. Instrum. Methods B 214 211) at Darmstadt will be a very efficient tool to create high-energy-density (HED) states in matter including strongly coupled plasmas. In this paper we show, with the help of two-dimensional numerical simulations, the interesting physical states that can be achieved considering different beam intensities using zinc as a test material. Another very interesting experiment that can be performed using the intense heavy-ion beam at FAIR will be generation of low-entropy compression of a test material such as hydrogen that is enclosed in a cylindrical shell of a high-Z material such as lead or gold. In such an experiment, one can study the problem of hydrogen metallization and the interiors of giant planets. Moreover, we discuss an interesting method to diagnose the HED matter that is at the centre of the Sun. We have ...
Energy Technology Data Exchange (ETDEWEB)
Tahir, N A [Gesellschaft fuer Schwerionenforschung, 64291 Darmstadt (Germany); Lomonosov, I V [Institute for Problems of Chemical Physics Research, Chernogolovka (Russian Federation); Shutov, A [Institute for Problems of Chemical Physics Research, Chernogolovka (Russian Federation); Udrea, S [Institut fuer Kernphysik, TU Darmstadt, 64289 Darmstadt (Germany); Deutsch, C [LPGP, Universite Paris-Sud, 91405 Orsay (France); Fortov, V E [Institute for Problems of Chemical Physics Research, Chernogolovka (Russian Federation); Gryaznov, V [Institute for Problems of Chemical Physics Research, Chernogolovka (Russian Federation); Hoffmann, D H H [Gesellschaft fuer Schwerionenforschung, 64291 Darmstadt (Germany); Jacobi, J [Institut fuer Angewandte Physik, Universitaet Frankfurt, 60438 Frankfurt (Germany); Kain, V [CERN, 1211 Geneva (Switzerland); Kuster, M [Institut fuer Kernphysik, TU Darmstadt, 64289 Darmstadt (Germany); Ni, P [Institut fuer Kernphysik, TU Darmstadt, 64289 Darmstadt (Germany); Piriz, A R [ETSI Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain); Schmidt, R [CERN, 1211 Geneva (Switzerland); Spiller, P [Gesellschaft fuer Schwerionenforschung, 64291 Darmstadt (Germany); Varentsov, D [Institut fuer Kernphysik, TU Darmstadt, 64289 Darmstadt (Germany); Zioutas, K [CERN, 1211 Geneva (Switzerland)
2006-04-28
Detailed theoretical studies have shown that intense heavy-ion beams that will be generated at the future Facility for Antiprotons and Ion Research (FAIR) (Henning 2004 Nucl. Instrum. Methods B 214 211) at Darmstadt will be a very efficient tool to create high-energy-density (HED) states in matter including strongly coupled plasmas. In this paper we show, with the help of two-dimensional numerical simulations, the interesting physical states that can be achieved considering different beam intensities using zinc as a test material. Another very interesting experiment that can be performed using the intense heavy-ion beam at FAIR will be generation of low-entropy compression of a test material such as hydrogen that is enclosed in a cylindrical shell of a high-Z material such as lead or gold. In such an experiment, one can study the problem of hydrogen metallization and the interiors of giant planets. Moreover, we discuss an interesting method to diagnose the HED matter that is at the centre of the Sun. We have also carried out simulations to study the damage caused by the full impact of the Large Hadron Collider (LHC) beam on a superconducting magnet. An interesting outcome of this study is that the LHC beam can induce HED states in matter.
Li, Meng; Gu, Xian-Ming; Huang, Chengming; Fei, Mingfa; Zhang, Guoyu
2018-04-01
In this paper, a fast linearized conservative finite element method is studied for solving the strongly coupled nonlinear fractional Schrödinger equations. We prove that the scheme preserves both the mass and energy, which are defined by virtue of some recursion relationships. Using the Sobolev inequalities and then employing the mathematical induction, the discrete scheme is proved to be unconditionally convergent in the sense of L2-norm and H α / 2-norm, which means that there are no any constraints on the grid ratios. Then, the prior bound of the discrete solution in L2-norm and L∞-norm are also obtained. Moreover, we propose an iterative algorithm, by which the coefficient matrix is independent of the time level, and thus it leads to Toeplitz-like linear systems that can be efficiently solved by Krylov subspace solvers with circulant preconditioners. This method can reduce the memory requirement of the proposed linearized finite element scheme from O (M2) to O (M) and the computational complexity from O (M3) to O (Mlog M) in each iterative step, where M is the number of grid nodes. Finally, numerical results are carried out to verify the correction of the theoretical analysis, simulate the collision of two solitary waves, and show the utility of the fast numerical solution techniques.
Ghosh, Samiran
2014-09-01
The propagation of a nonlinear low-frequency mode in two-dimensional (2D) monolayer hexagonal dusty plasma crystal in presence of external magnetic field and dust-neutral collision is investigated. The standard perturbative approach leads to a 2D Korteweg-de Vries (KdV) soliton for the well-known dust-lattice mode. However, the Coriolis force due to crystal rotation and Lorentz force due to magnetic field on dust particles introduce a linear forcing term, whereas dust-neutral drag introduce the usual damping term in the 2D KdV equation. This new nonlinear equation is solved both analytically and numerically to show the competition between the linear forcing and damping in the formation of quasilongitudinal soliton in a 2D strongly coupled complex (dusty) plasma. Numerical simulation on the basis of the typical experimental plasma parameters and the analytical solution reveal that the neutral drag force is responsible for the usual exponential decay of the soliton, whereas Coriolis and/or Lorentz force is responsible for the algebraic decay as well as the oscillating tail formation of the soliton. The results are discussed in the context of the plasma crystal experiment.
Gupta, Akanksha; Ganesh, Rajaraman
2018-01-01
We study compressibility effects on the two-dimensional strongly coupled dusty plasma by means of computational fluid dynamics (CFD) with the Kolmogorov flow as an initial shear flow profile. Nonlinear compressible vortex flow dynamics and other linear and nonlinear properties of such flow in the presence of variable density, pressure, and electrostatic potential are addressed using a generalised compressible hydrodynamic model. The stabilizing effect of compressibility on the unstable shear flows in the presence of strong correlation ( τm>0 ) is presented. Increasing the Mach number relatively reduces the growth-rate of perturbation. On the other hand, strong correlation makes the medium to be more unstable and increases the growth rate. Using an eigen value solver, various linear properties of compressible Kolmogorov flow have been investigated for a range of variable parameters, for example, Mach number, Reynolds number, and viscoelastic coefficient (τm). Compressible Kolmogorov flow becomes unstable above a critical value of the Reynolds number (Rc), and below Rc, the shear flow is found to be neutrally stable. In this study, it is found that the viscoelasticity reduces the value of Rc. For our choice of parameters, at τm=τmc , the compressible Kolmogorov flow becomes unconditionally unstable and no Rc exists for values of τm higher than τmc . To address the nonlinear properties, for example, mode-mode interaction due to the presence of nonlinearity in the fluid, vortex formation, etc., a massively parallelized Advanced Generalized SPECTral Code (AG-Spect) has been developed. AG-Spect, a newly developed code, is an efficient tool to solve any set of nonlinear fluid dynamic equations. A good agreement in linear growth rates obtained from the eigen value solver and time dependent simulation (AG-Spect) is found. In our CFD study, the suppression of instability, elongated vortex structures, pattern formation, nonlinear saturation, and visco
Importance of strong-correlation on the lattice dynamics of light-actinides Th-Pa alloy
de La Peã+/-A Seaman, Omar; Heid, Rolf; Bohnen, Klaus-Peter
We have studied the structural, electronic, and lattice dynamics of the Th1-xPax actinide alloy. This system have been analyzed within the framework of density functional perturbation theory, using a mixed-basis pseudopotential method and the virtual crystal approximation (VCA) for modeling the alloy. In particular, the energetics is analyzed as the ground-state crystal structure is changed form fcc to bct, as well as the electronic density of states (DOS), and the phonon frequencies. Such properties have been calculated with and without strong correlations effects through the LDA+U formalism. Although the strong-correlation does not influence on a great manner the Th properties, such effects are more important as the content increases towards Pa, affecting even the definition of the ground-state crystal structure for Pa (experimentally determined as bct). The evolution of the density of states at the Fermi level (N (EF)) and the phonon frequencies as a function of Pa-content are presented and discussed in detail, aiming to understand their influence on the electron-phonon coupling for the Th-Pa alloy. This research was supported by Conacyt-México under project No. CB2013-221807-F.
Energy Technology Data Exchange (ETDEWEB)
Devoret, M.H. [College de France, 75231 Paris cedex 05 (France); Girvin, Steven; Schoelkopf, Robert [Applied Physics Department, Yale University, New Haven, CT 06520-8284 (United States)
2007-10-15
After reviewing the limitation by the fine structure constant {alpha} of the dimensionless coupling constant of an hydrogenic atom with a mode of the electromagnetic field in a cavity, we show that the situation presents itself differently for an artificial Josephson atom coupled to a transmission line resonator. Whereas the coupling constant for the case where such an atom is placed inside the dielectric of the resonator is proportional to {alpha}{sup 1/2}, the coupling of the Josephson atom when it is placed in series with the conducting elements of the resonator is proportional to {alpha}{sup -1/2} and can reach values greater than 1. (Abstract Copyright [2007], Wiley Periodicals, Inc.)
International Nuclear Information System (INIS)
Achterberg, O.; D'Agostini, G.; Apel, W.D.; Engler, J.; Fluegge, G.; Forstbauer, B.; Fries, D.C.; Fues, W.; Gamerdinger, K.; Henkes, T.; Hopp, G.; Krueger, M.; Kuester, H.; Mueller, H.; Randoll, H.; Schmidt, G.; Schneider, H.; Boer, W. de; Buschhorn, G.; Grindhammer, G.; Grosse-Wiesmann, P.; Gunderson, B.; Kiesling, C.; Kotthaus, R.; Kruse, U.; Lierl, H.; Lueers, D.; Oberlack, H.; Schacht, P.; Bonneaud, G.; Colas, P.; Cordier, A.; Davier, M.; Fournier, D.; Grivaz, J.F.; Haissinski, J.; Journe, V.; Laplanche, F.; Le Diberder, F.; Mallik, U.; Ros, E.; Veillet, J.J.; Behrend, H.J.; Fenner, H.; Schachter, M.J.; Schroeder, V.; Sindt, H.
1983-12-01
Hadronic events obtained with the CELLO detector at PETRA are compared with second order QCD predictions using different models for the fragmentation of quarks and gluons into hadrons. We find that the model dependence in the determination of the strong coupling constant persists when going from first to second order QCD calculations. (orig.)
Gaaloul, Sana; Delinchant, Benoît; Wurtz, Frédéric; Thiers, Stéphane; Peuportier, Bruno
2011-01-01
International audience; The context of this study is the coupling of thermal and electrical models in order to efficiently simulate energy consumption in buildings, which requires managing interoperability problems between simulation environments. The coupling is accomplished in MATLAB™ tool between a thermal model of a building envelope using COMFIE software and an electrical heater model. Our purpose is to study and generalize the interoperability between these two domains governed by pheno...
Takigawa, N.; Michel, F.; Balantekin, A. B.; Reidemeister, G.
1991-06-01
We offer a novel interpretation of the deviation of the experimental angular distribution for elastic 18O+ 184W scattering at 90 MeV from the standard Fresnel diffraction pattern in terms of an interference between scattering amplitudes corresponding to different orientations of the target nucleus. The importance of Coriolis coupling, which is initially neglected in this geometric approach, is discussed in the case where long-range Coulomb coupling is active.
Energy Technology Data Exchange (ETDEWEB)
Takigawa, N. (Tohoku Univ., Sendai (Japan). Dept. of Physics); Michel, F. (Mons Univ. (Belgium). Faculte des Sciences); Balantekin, A.B. (Wisconsin Univ., Madison (USA). Dept. of Physics); Reidemeister, G. (Universite Libre de Bruxelles (Belgium). Faculte des Sciences)
1991-06-20
We offer a novel interpretation of the deviation of the experimental angular distribution for elastic {sup 18}O+{sup 184}W scattering at 90 MeV from the standard Fresnel diffraction pattern in terms of an interference between scattering amplitudes corresponding to different orientations of the target nucleus. The importance of Coriolis coupling, which is initially neglected in this geometric approach, is discussed in the case where long-range Coulomb coupling is active. (orig.).
Continuum strong-coupling expansion of Yang-Mills theory: quark confinement and infra-red slavery
Energy Technology Data Exchange (ETDEWEB)
Mansfield, P. (Dept. of Mathematical Sciences, Univ. of Durham (United Kingdom))
1994-04-25
We solve Schroedinger's equation for the ground-state of four-dimensional Yang-Mills theory as an expansion in inverse powers of the coupling. Expectation values computed with the leading-order approximation are reduced to a calculation in two-dimensional Yang-Mills theory which is known to confine. Consequently the Wilson loop in the four-dimensional theory obeys an area law to leading order and the coupling becomes infinite as the mass scale goes to zero. (orig.)
Continuum strong-coupling expansion of Yang-Mills theory: quark confinement and infra-red slavery
Mansfield, Paul
1994-04-01
We solve Schrödinger's equation for the ground-state of four-dimensional Yang-Mills theory as an expansion in inverse powers of the coupling. Expectation values computed with the leading-order approximation are reduced to a calculation in two-dimensional Yang-Mills theory which is known to confine. Consequently the Wilson loop in the four-dimensional theory obeys an area law to leading order and the coupling becomes infinite as the mass scale goes to zero.
Casalderrey-Solana, Jorge; Milhano, José Guilherme; Pablos, Daniel; Rajagopal, Krishna
2016-01-01
We have previously introduced a hybrid strong/weak coupling model for jet quenching in heavy ion collisions that describes the production and fragmentation of jets at weak coupling, using PYTHIA, and describes the rate at which each parton in the jet shower loses energy as it propagates through the strongly coupled plasma, dE/dx, using an expression computed holographically at strong coupling. The model has a single free parameter that we fit to a single experimental measurement. We then confront our model with experimental data on many other jet observables, focusing here on boson-jet observables, finding that it provides a good description of present jet data. Next, we provide the predictions of our hybrid model for many measurements to come, including those for inclusive jet, dijet, photon-jet and Z-jet observables in heavy ion collisions with energy $\\sqrt{s}=5.02$ ATeV coming soon at the LHC. As the statistical uncertainties on near-future measurements of photon-jet observables are expected to be much sm...
Electron-photon coupling in semimetals in a high magnetic field
Energy Technology Data Exchange (ETDEWEB)
Mihaila, Bogdan [Los Alamos National Laboratory; Albers, Robert C [Los Alamos National Laboratory; Littlewood, Peter B [U. CAMBRIDGE/UK
2009-01-01
We consider the effect of electron-phonon coupling in semimetals in high magnetic fields, with regard to elastic modes that can lead to a redistribution of carriers between pockets. We show that in a clean three dimensional system, at each Landau level crossing, this leads to a discontinuity in the magnetostriction, and a divergent contribution to the elastic modulus. We estimate the magnitude of this effect in the group V semimetal Bismuth.
Yoshiki, Wataru; Chen-Jinnai, Akitoshi; Tetsumoto, Tomohiro; Tanabe, Takasumi
2015-11-30
We report the first experimental observation of an energy oscillation between two coupled ultra-high Q whispering gallery modes in the time domain. Two counter-propagating whispering gallery modes in a silica toroid microcavity were employed for this purpose. The combination of a large coupling coefficient between the two modes and an ultra-high Q factor, which creates a large Γ value of > 10, results in a clear energy oscillation. Our measurement is based on a drop-port measurement technique, which enables us to observe the light energy in the two modes directly. The oscillation period measured in the time domain precisely matched that inferred from mode splitting in the frequency domain, and the measured results showed excellent agreement with results calculated with the developed numerical model.
Strong spin-phonon coupling in infrared and Raman spectra of SrMnO.sub.3./sub..
Czech Academy of Sciences Publication Activity Database
Kamba, Stanislav; Goian, Veronica; Skoromets, Volodymyr; Hejtmánek, Jiří; Bovtun, Viktor; Kempa, Martin; Borodavka, Fedir; Vaněk, Přemysl; Belik, A.A.; Lee, J.H.; Pacherová, Oliva; Rabe, K.M.
2014-01-01
Roč. 89, č. 6 (2014), "064308-1"-"064308-9" ISSN 1098-0121 R&D Projects: GA MŠk LH13048; GA ČR GAP204/12/1163; GA MŠk LD12026; GA ČR GP14-14122P Institutional support: RVO:68378271 Keywords : multiferroics * spin-phonon coupling * infrared and Raman spectra Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.736, year: 2014
Energy Technology Data Exchange (ETDEWEB)
Malerba, M.; De Angelis, F., E-mail: francesco.deangelis@iit.it [Istituto Italiano di Tecnologia, Via Morego, 30, I-16163 Genova (Italy); Ongarello, T.; Paulillo, B.; Manceau, J.-M.; Beaudoin, G.; Sagnes, I.; Colombelli, R., E-mail: raffaele.colombelli@u-psud.fr [Centre for Nanoscience and Nanotechnology (C2N Orsay), CNRS UMR9001, Univ. Paris Sud, Univ. Paris Saclay, 91405 Orsay (France)
2016-07-11
We report a crucial step towards single-object cavity electrodynamics in the mid-infrared spectral range using resonators that borrow functionalities from antennas. Room-temperature strong light-matter coupling is demonstrated in the mid-infrared between an intersubband transition and an extremely reduced number of sub-wavelength resonators. By exploiting 3D plasmonic nano-antennas featuring an out-of-plane geometry, we observed strong light-matter coupling in a very low number of resonators: only 16, more than 100 times better than what reported to date in this spectral range. The modal volume addressed by each nano-antenna is sub-wavelength-sized and it encompasses only ≈4400 electrons.
Energy Technology Data Exchange (ETDEWEB)
Abazov, V.M.; /Dubna, JINR; Abbott, B.; /Oklahoma U.; Abolins, M.; /Michigan State U.; Acharya, B.S.; /Tata Inst.; Adams, M.; /Illinois U., Chicago; Adams, T.; /Florida State U.; Aguilo, E.; /Alberta U. /Simon Fraser U. /York U., Canada /McGill U.; Ahsan, M.; /Kansas State U.; Alexeev, G.D.; /Dubna, JINR; Alkhazov, G.; /St. Petersburg, INP; Alton, A.; /Michigan U. /Northeastern U.
2009-11-01
We determine the strong coupling constant {alpha}{sub s} and its energy dependence from the p{sub T} dependence of the inclusive jet cross section in p{bar p} collisions at {radical}s = 1.96 TeV. The strong coupling constant is determined over the transverse momentum range 50 < p{sub T} < 145 GeV. Using perturbative QCD calculations to order {Omicron}({alpha}{sub s}{sup 3}) combined with {Omicron}({alpha}{sub s}{sup 4}) contributions from threshold corrections, we obtain {alpha}{sub s}(M{sub Z}) = 0.1173{sub -0.0049}{sup +0.0041}. This is the most precise result obtained at a hadron-hadron collider.
Arakawa, Naoya
2016-11-01
I propose the emergence of the spin-orbital-coupled vector chirality in a nonfrustrated Mott insulator with the strong spin-orbit coupling due to a b -plane's inversion-symmetry (IS) breaking. I derive the superexchange interactions for a t2 g-orbital Hubbard model on a square lattice with the strong spin-orbit coupling and the IS-breaking-induced hopping integrals, and explain the microscopic origins of the Dzyaloshinsky-Moriya (DM) -type and the Kitaev-type interactions. Then, by adopting the mean-field approximation to a minimal model including only the Heisenberg-type and the DM-type nearest-neighbor interactions, I show that the IS breaking causes the spin-orbital-coupled chirality as a result of stabilizing the screw state. I also highlight the limit of the hard-pseudospin approximation in discussing the stability of the screw states in the presence of both the DM-type and the Kitaev-type interactions, and discuss its meaning. I finally discuss the effects of tetragonal crystal field and Jeff=3/2 states, and the application to the iridates near the [001 ] surface of Sr2IrO4 and the interface between Sr2IrO4 and Sr3Ir2O7 .
Energy Technology Data Exchange (ETDEWEB)
Abazov, V.M. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Abbott, B. [University of Oklahoma, Norman, OK 73019 (United States); Acharya, B.S. [Tata Institute of Fundamental Research, Mumbai (India); Adams, M. [University of Illinois at Chicago, Chicago, IL 60607 (United States); Adams, T. [Florida State University, Tallahassee, FL 32306 (United States); Alexeev, G.D. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Alkhazov, G. [Petersburg Nuclear Physics Institute, St. Petersburg (Russian Federation); Alton, A. [University of Michigan, Ann Arbor, MI 48109 (United States); Alverson, G. [Northeastern University, Boston, MA 02115 (United States); Askew, A. [Florida State University, Tallahassee, FL 32306 (United States); Atkins, S. [Louisiana Tech University, Ruston, LA 71272 (United States); Augsten, K. [Czech Technical University in Prague, Prague (Czech Republic); Avila, C. [Universidad de los Andes, Bogota (Colombia); Badaud, F. [LPC, Universite Blaise Pascal, CNRS/IN2P3, Clermont (France); Bagby, L.; Baldin, B. [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Bandurin, D.V. [Florida State University, Tallahassee, FL 32306 (United States); Banerjee, S. [Tata Institute of Fundamental Research, Mumbai (India); Barberis, E. [Northeastern University, Boston, MA 02115 (United States); Baringer, P. [University of Kansas, Lawrence, KS 66045 (United States); and others
2012-11-15
We present a measurement of the average value of a new observable at hadron colliders that is sensitive to QCD dynamics and to the strong coupling constant, while being only weakly sensitive to parton distribution functions. The observable measures the angular correlations of jets and is defined as the number of neighboring jets above a given transverse momentum threshold which accompany a given jet within a given distance {Delta}R in the plane of rapidity and azimuthal angle. The ensemble average over all jets in an inclusive jet sample is measured and the results are presented as a function of transverse momentum of the inclusive jets, in different regions of {Delta}R and for different transverse momentum requirements for the neighboring jets. The measurement is based on a data set corresponding to an integrated luminosity of 0.7 fb{sup -1} collected with the D0 detector at the Fermilab Tevatron Collider in pp{sup Macron} collisions at {radical}(s)=1.96 TeV. The results are well described by a perturbative QCD calculation in next-to-leading order in the strong coupling constant, corrected for non-perturbative effects. From these results, we extract the strong coupling and test the QCD predictions for its running over a range of momentum transfers of 50-400 GeV.
Ultrafast electron-lattice coupling dynamics in VO2 and V2O3 thin films
Abreu, Elsa; Gilbert Corder, Stephanie N.; Yun, Sun Jin; Wang, Siming; Ramírez, Juan Gabriel; West, Kevin; Zhang, Jingdi; Kittiwatanakul, Salinporn; Schuller, Ivan K.; Lu, Jiwei; Wolf, Stuart A.; Kim, Hyun-Tak; Liu, Mengkun; Averitt, Richard D.
2017-09-01
Ultrafast optical pump-optical probe and optical pump-terahertz probe spectroscopy were performed on vanadium dioxide (VO2) and vanadium sesquioxide (V2O3 ) thin films over a wide temperature range. A comparison of the experimental data from these two different techniques and two different vanadium oxides, in particular a comparison of the spectral weight oscillations generated by the photoinduced longitudinal acoustic modulation, reveals the strong electron-phonon coupling that exists in both materials. The low-energy Drude response of V2O3 appears more amenable than VO2 to ultrafast strain control. Additionally, our results provide a measurement of the temperature dependence of the sound velocity in both systems, revealing a four- to fivefold increase in VO2 and a three- to fivefold increase in V2O3 across the insulator-to-metal phase transition. Our data also confirm observations of strong damping and phonon anharmonicity in the metallic phase of VO2, and suggest that a similar phenomenon might be at play in the metallic phase of V2O3 . More generally, our simple table-top approach provides relevant and detailed information about dynamical lattice properties of vanadium oxides, paving the way to similar studies in other complex materials.
Energy Technology Data Exchange (ETDEWEB)
Foulk, James W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Alleman, Coleman N. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mota, Alejandro [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lim, Hojun [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Littlewood, David John [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bergel, Guy Leshem [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Popova, Evdokia [Georgia Inst. of Technology, Atlanta, GA (United States). Woodruff School of Mechanical Engineering; Montes de Oca Zapiain, David [Georgia Inst. of Technology, Atlanta, GA (United States). Woodruff School of Mechanical Engineering; Kalidindi, Suryanarayana Raju [Georgia Inst. of Technology, Atlanta, GA (United States). Woodruff School of Mechanical Engineering; Ernst, Corey [Elemental Technologies, Provo, UT (United States)
2017-09-01
The heterogeneity in mechanical fields introduced by microstructure plays a critical role in the localization of deformation. To resolve this incipient stage of failure, it is therefore necessary to incorporate microstructure with sufficient resolution. On the other hand, computational limitations make it infeasible to represent the microstructure in the entire domain at the component scale. In this study, the authors demonstrate the use of concurrent multi- scale modeling to incorporate explicit, finely resolved microstructure in a critical region while resolving the smoother mechanical fields outside this region with a coarser discretization to limit computational cost. The microstructural physics is modeled with a high-fidelity model that incorporates anisotropic crystal elasticity and rate-dependent crystal plasticity to simulate the behavior of a stainless steel alloy. The component-scale material behavior is treated with a lower fidelity model incorporating isotropic linear elasticity and rate-independent J 2 plas- ticity. The microstructural and component scale subdomains are modeled concurrently, with coupling via the Schwarz alternating method, which solves boundary-value problems in each subdomain separately and transfers solution information between subdomains via Dirichlet boundary conditions. Beyond cases studies in concurrent multiscale, we explore progress in crystal plastic- ity through modular designs, solution methodologies, model verification, and extensions to Sierra/SM and manycore applications. Advances in conformal microstructures having both hexahedral and tetrahedral workflows in Sculpt and Cubit are highlighted. A structure-property case study in two-phase metallic composites applies the Materials Knowledge System to local metrics for void evolution. Discussion includes lessons learned, future work, and a summary of funded efforts and proposed work. Finally, an appendix illustrates the need for two-way coupling through a single degree of
Pixley, J. H.; Cole, William S.; Spielman, I. B.; Rizzi, Matteo; Das Sarma, S.
2017-10-01
We study the odd-integer filled Mott phases of a spin-1 Bose-Hubbard chain and determine their fate in the presence of a Raman induced spin-orbit coupling which has been achieved in ultracold atomic gases; this system is described by a quantum spin-1 chain with a spiral magnetic field. The spiral magnetic field initially induces helical order with either ferromagnetic or dimer order parameters, giving rise to a spiral paramagnet at large field. The spiral ferromagnet-to-paramagnet phase transition is in a universality class with critical exponents associated with the divergence of the correlation length ν ≈2 /3 and the order-parameter susceptibility γ ≈1 /2 . We solve the effective spin model exactly using the density-matrix renormalization group, and compare with both a large-S classical solution and a phenomenological Landau theory. We discuss how these exotic bosonic magnetic phases can be produced and probed in ultracold atomic experiments in optical lattices.
Wang, Hai; Toma, Andrea; Wang, Hai-Yu; Bozzola, Angelo; Miele, Ermanno; Haddadpour, Ali; Veronis, Georgios; De Angelis, Francesco; Wang, Lei; Chen, Qi-Dai; Xu, Huai-Liang; Sun, Hong-Bo; Zaccaria, Remo Proietti
2016-07-21
We have investigated the influence of Rabi splitting tuning on the dynamics of strongly coupled J-aggregate/surface plasmon polariton systems. In particular, the Rabi splitting was tuned by modifying the J-aggregate molecule concentration while a polaritonic system was provided by a nanostructure formed by holes array in a golden layer. From the periodic and concentration changes we have identified, through numerical and experimental steady-state analyses, the best geometrical configuration for maximizing Rabi splitting, which was then used for transient absorption measurements. It was found that in transient absorption spectra, under upper band excitation, two bleaching peaks appear when a nanostructured polaritonic pattern is used. Importantly, their reciprocal distance increases upon increase of J-aggregate concentration, a result confirmed by steady-state analysis. In a similar manner it was also found that the lifetime of the upper band is intimately related to the coupling strength. In particular, we argue that with strong coupling strength, i.e. high J-aggregate concentration, a short lifetime of the upper band has to be expected due to the suppression of the bottleneck effect. This result supports the idea that the dynamics of hybrid systems is profoundly dependent on Rabi splitting.
International Nuclear Information System (INIS)
Roiban, R.; Tseytlin, A. A.
2008-01-01
We consider folded (S,J) spinning strings in AdS 5 xS 5 (with one spin component in AdS 5 and a one in S 5 ) corresponding to the Tr(D S Φ J ) operators in the sl(2) sector of the N=4 super Yang-Mills theory in the special scaling limit in which both the string mass ∼√(λ)lnS and J are sent to infinity with their ratio fixed. Expanding in the parameter l=(J/√(λ)lnS) we compute the 2-loop string sigma-model correction to the string energy and show that it agrees with the expression proposed by Alday and Maldacena [J. High Energy Phys. 11 (2007) 019]. We suggest that a resummation of the logarithmic l 2 ln n l terms is necessary in order to establish an interpolation to the weakly coupled gauge-theory results. In the process, we set up a general framework for the calculation of higher loop corrections to the energy of multispin string configurations. In particular, we find that in addition to the direct 2-loop term in the string energy there is a contribution from lower loop order due to a finite 'renormalization' of the relation between the parameters of the classical solution and the fixed spins, i.e., the charges of the SO(2,4)xSO(6) symmetry.
International Nuclear Information System (INIS)
Sherman, A.; Schreiber, M.
1995-01-01
We use the Eliashberg formalism for calculating T c in a model of cuprate perovskites with pairing mediated by both magnons and apex-oxygen vibrations. The influence of strong correlations on the energy spectrum is taken into account in the spin-wave approximation. It is shown that the hole-magnon interaction alone cannot yield high T c . But together with a moderate hole-phonon interaction it does lead to d-wave superconductivity at temperatures and hole concentrations observed in cuprates. High T c are connected with a large density of states due to extended Van Hove singularities, a conformity of the two interactions for the d symmetry, and high phonon frequencies
Directory of Open Access Journals (Sweden)
James Avery Sauls
2015-06-01
Full Text Available Recent theories of Sr2RuO4 based on the interplay of strong interactions, spin-orbit coupling and multi-band anisotropy predict chiral or helical ground states with strong anisotropy of the pairing states, with deep minima in the excitation gap, as well as strong phase anisotropy for the chiral ground state. We develop time-dependent mean field theory to calculate the Bosonic spectrum for the class of 2D chiral superconductors spanning 3He-A to chiral superconductors with strong anisotropy. Chiral superconductors support a pair of massive Bosonic excitations of the time-reversed pairs labeled by their parity under charge conjugation. These modes are degenerate for 2D 3He-A. Crystal field anisotropy lifts the degeneracy. Strong anisotropy also leads to low-lying Fermions, and thus to channels for the decay of the Bosonic modes. Selection rules and phase space considerations lead to large asymmetries in the lifetimes and hybridization of the Bosonic modes with the continuum of un-bound Fermion pairs. We also highlight results for the excitation of the Bosonic modes by microwave radiation that provide clear signatures of the Bosonic modes of an anisotropic chiral ground state.
Leupold, D; Ehlert, J; Irrgang, K D; Renger, G; Lokstein, H
2002-01-01
Stepwise two-photon excitation of chlorophyll a and b in the higher plant main light-harvesting complex (LHC II) and the minor complex CP29 (as well as in organic solution) with 100-fs pulses in the Q/sub y/ region results in a weak blue fluorescence. The dependence of the spectral shape of the blue fluorescence on excitation wavelength offers a new approach to elucidate the long-standing problem of the origin of spectral "chlorophyll forms" in pigment-protein complexes, in particular the characterization of chlorophyll a/b-heterodimers. As a first result we present evidence for the existence of strong chlorophyll a/b-interactions (excitonically coupled transitions at 650 and 680 nm) in LHC II at ambient temperature. In comparison with LHC II, the experiments with CP29 provide further evidence that the lowest energy chlorophyll a transition (at ~680 nm) is not excitonically coupled to chlorophyll b. (22 refs).
International Nuclear Information System (INIS)
Wang, Yinling; Wang, Zhangcui; Wu, Xiaoqin; Liu, Xiaowang; Li, Maoguo
2016-01-01
Highlights: • CoAl-LDHs were synthesized on the surface of graphene oxide in situ. • The oxygen reduction reaction activity of the catalyst was investigated. • The synergistic effect between CoAl-LDHs and rGO is discussed in detail. • The roles of Co 2+ in the LDHs were clarified. - Abstract: Precious metal-free electrocatalysts with high efficiency and durability for the oxygen reduction reaction (ORR) are strongly desired in the field of energy technology. Herein, the CoAl layered double hydroxides (CoAl-LDHs)/reduced graphene oxide (rGO) composites were successfully prepared by growing CoAl-LDHs on the surface of GO in situ via coprecipitation and subsequently hydrothermal treatment. The structure, composition, morphology and ORR catalytic activity of the CoAl-LDHs/rGO composites were investigated as a function of mass ratios of CoAl-LDHs and GO. The results show that there is an optimum mass ratio of CoAl-LDHs and GO (w CoAl-LDHs :w GO = 1:5) for the ORR catalytic activity, where the electron transfer number for ORR at the CoAl-LDHs/rGO composites reaches to 3.5, closing to the full four-electron process. The synergistic effect between CoAl-LDHs and rGO is discussed in detail and the discussion is instructive for the construction of the better transition metal oxides/carbon composite-based ORR catalysts.
International Nuclear Information System (INIS)
Min, Shixiong; Hou, Jianhua; Lei, Yonggang; Ma, Xiaohua; Lu, Gongxuan
2017-01-01
Highlights: • TiO 2 /GQDs composites were prepared by a facile one-step hydrothermal method. • GQDs were strongly coupled onto the surface of TiO 2 nanoparticles by this method. • The TiO 2 /GQDs showed enhanced light absorption and charge separation efficiency. • The TiO 2 /GQDs exhibited higher photocatalytic H 2 evolution activity than pure TiO 2 . • GQDs play synergistic roles by acting as both photosensitizer and electron acceptor. - Abstract: The coupling of semiconductor photocatalysts with graphene quantum dots (GQDs) has been proven to be an effective strategy to enhance the photocatalytic and photoelectrical conversion performances of the resulted composites; however, the preparation of semiconductor/GQDs composites usually involves several time-inefficient and tedious post-treatment steps. Herein, we present a facile one-step hydrothermal route for the preparation of GQDs coupled TiO 2 (TiO 2 /GQDs) photocatalysts using 1,3,6-trinitropyrene (TNP) as the sole precursor of GQDs. During the hydrothermal process, TNP molecules undergo an intramolecular fusion to form GQDs, which simultaneously decorate on the surface of TiO 2 nanoparticles, leading to a strong surface interaction between the two components. The effective coupling of GQDs on TiO 2 can effectively extend the light absorption of the TiO 2 to visible region and enhance the charge separation efficiency of TiO 2 /GQDs composites as a result of GQDs acting as a photosensitizer and an excellent electron acceptor. These key advances make the TiO 2 /GQDs photocatalyst highly active towards the H 2 evolution reaction, resulting in 7 and 3 times higher H 2 evolution rate and photocurrent response at optimal GQDs content than TiO 2 alone, respectively. This study provides a new methodology for the development of high-performance GQDs modified semiconductor photocatalysts for energy conversion applications.
Reuvekamp, Patrick; Caslin, Kevin; Guguchia, Zurab; Keller, Hugo; Kremer, Reinhard K; Simon, Arndt; Köhler, Jürgen; Bussmann-Holder, Annette
2015-07-08
EuTiO3 exhibits strong magneto-electric coupling at the onset of antiferromagnetic order below TN = 5.7 K. The dielectric permittivity drops at TN by 7% and recovers to normal values with increasing magnetic field. This effect is shown to stem from tiny lattice effects as seen in magnetostriction data which directly affect the soft optic mode and its polarizability coordinate. By combining experimental results with theory we show that marginal changes in the lattice parameter of the order of 0.01% have a more than 1000% effect on the transverse optic soft mode of ETO and thus easily induce a ferroelectric instability.
Directory of Open Access Journals (Sweden)
Maxim Goryachev
2018-04-01
Full Text Available A quartz Bulk Acoustic Wave resonator is designed to coherently trap phonons in such a way that they are well confined and immune to suspension losses so they exhibit extremely high acoustic Q-factors at low temperature, with Q × f products of order 10 18 Hz. In this work we couple such a resonator to a Superconducting Quantum Interference Device (SQUID amplifier and investigate effects in the strong signal regime. Both parallel and series connection topologies of the system are investigated. The study reveals significant non-Duffing response that is associated with the nonlinear characteristics of Josephson junctions. The nonlinearity provides quasi-periodic structure of the spectrum in both incident power and frequency. The result gives an insight into the open loop behaviour of a future Cryogenic Quartz Oscillator in the strong signal regime.
Endrizzi, S.
2011-12-01
GEOtop is a small scale grid-based model that couples the soil heat and water budgets, represents the energy exchange with the atmosphere considering the radiative and turbulent fluxes, and describes the subsurface water flow in its fully three-dimensional nature. In particular, the model reproduces the strong coupling between water and energy balance during soil freezing and thawing processes, considering the highly non-linear heat capacity effect resulting from phase change. In addition, it describes the water and energy budgets in the snow cover, represents blowing snow, and models the temporal evolution of the snow depth and, therefore, its effect on soil temperature. Infiltration in frozen soil and runoff are also represented. Vegetation effects are considered, in particular as regards snow interception, trapping, and the interactions with turbulent and radiative heat exchange. GEOtop is therefore a very useful tool in several applications that involve permafrost and seasonally-frozen soils, both in high altitude and latitude regions. In particular, GEOtop allows evaluating the effects of water lateral transport in the freezing/thawing process, effects that are often neglected, but may be significant. Applications are shown for i) a typical peat-covered arctic environment, where the position of the frost table controls the runoff production rate, due to the strong decrease of the soil hydraulic conductivity with depth; and ii) an alpine site, where borehole data are used to test the model and the effect of the upslope drainage distance is studied.
Chen, Yuting; Yang, Taiqun; Pan, Haifeng; Yuan, Yufeng; Chen, Li; Liu, Mengwei; Zhang, Kun; Zhang, Sanjun; Wu, Peng; Xu, Jianhua
2014-02-05
Using carboxylate-protected silver nanoclusters (Ag-carboxylate NCs) as a model, we separately investigated the contribution of the ligand shell and the metal core to understand the nature of photoluminescence of Ag NCs. A new Ag(0)NCs@Ag(I)-carboxylate complex core-shell structural model has been proposed. The emission from the Ag-carboxylate NCs could be attributed to ligand-to-metal-metal charge transfer from Ag(I)-carboxylate complexes (the oxygen atom in the carboxylate ligands to the Ag(I) ions) to the Ag atoms and subsequent radiative relaxation. Additionally, we found that the emission wavelength of the Ag NCs depends on the excitation wavelength implying a strong coupling between surface plasmon and emitter in Ag NCs. The strong coupling between the surface plasmon and the emitter determines the quantum yield and lifetime. The emission mechanism of Ag NCs and its relation to the organic templates and metal cores were clearly clarified. The results should stimulate additional experimental and theoretical research on the molecular-level design of luminescent metal probes for optoelectronics and other applications.
Sukharev, Maxim; Pachter, Ruth
2018-03-01
We study theoretically the optical response of a WS2 monolayer located near periodic metal nanostructured arrays in two and three dimensions. The emphasis of the simulations is on the strong coupling between excitons supported by WS2 and surface plasmon-polaritons supported by various periodic plasmonic interfaces. It is demonstrated that a monolayer of WS2 placed in close proximity of periodic arrays of either slits or holes results in a Rabi splitting of the corresponding surface plasmon-polariton resonance as revealed in calculated transmission and reflection spectra. The nonlinear regime, at which the few-layer WS2 exhibits experimentally third harmonic generation (THG), is studied in detail. Monolayer transition metal dichalcogenides (TMDs) do not exhibit THG because they are non-centrosymmetric, but here we use the monolayer as an approximation to a thin TMD nanostructure. We show that in the strong coupling regime the third harmonic signal is significantly affected by plasmon-polaritons and the symmetry of hybrid exciton-plasmon modes. It is also shown that the local electromagnetic field induced by plasmons is the major contributor to the enhancement of the third harmonic signal in three dimensions. The local electromagnetic fields resulting from the third harmonic generation are greatly localized and highly sensitive to the environment, thus making it a great tool for nano-probes.
Kim, Jong Min; Kim, Sung; Hwang, Sung Won; Kim, Chang Oh; Shin, Dong Hee; Kim, Ju Hwan; Jang, Chan Wook; Kang, Soo Seok; Hwang, Euyheon; Choi, Suk-Ho; El-Gohary, Sherif H.; Byun, Kyung Min
2018-02-01
Recently, we have demonstrated that excitation of plasmon-polaritons in a mechanically-derived graphene sheet on the top of a ZnO semiconductor considerably enhances its light emission efficiency. If this scheme is also applied to device structures, it is then expected that the energy efficiency of light-emitting diodes (LEDs) increases substantially and the commercial potential will be enormous. Here, we report that the plasmon-induced light coupling amplifies emitted light by ∼1.6 times in doped large-area chemical-vapor-deposition-grown graphene, which is useful for practical applications. This coupling behavior also appears in GaN-based LEDs. With AuCl3-doped graphene on Ga-doped ZnO films that is used as transparent conducting electrodes for the LEDs, the average electroluminescence intensity is 1.2–1.7 times enhanced depending on the injection current. The chemical doping of graphene may produce the inhomogeneity in charge densities (i.e., electron/hole puddles) or roughness, which can play a role as grating couplers, resulting in such strong plasmon-enhanced light amplification. Based on theoretical calculations, the plasmon-coupled behavior is rigorously explained and a method of controlling its resonance condition is proposed.
YBa{sub 2}Cu{sub 3}O{sub 7} microwave resonators for strong collective coupling with spin ensembles
Energy Technology Data Exchange (ETDEWEB)
Ghirri, A., E-mail: alberto.ghirri@nano.cnr.it [Istituto Nanoscienze - CNR, Centro S3, via Campi 213/a, 41125 Modena (Italy); Bonizzoni, C.; Affronte, M. [Dipartimento Fisica, Informatica e Matematica, Università di Modena e Reggio Emilia and Istituto Nanoscienze - CNR, Centro S3, via Campi 213/a, 41125 Modena (Italy); Gerace, D.; Sanna, S. [Dipartimento di Fisica, Università di Pavia, via Bassi 6, 27100 Pavia (Italy); Cassinese, A. [CNR-SPIN and Dipartimento di Fisica, Università di Napoli Federico II, 80138 Napoli (Italy)
2015-05-04
Coplanar microwave resonators made of 330 nm-thick superconducting YBa{sub 2}Cu{sub 3}O{sub 7} have been realized and characterized in a wide temperature (T, 2–100 K) and magnetic field (B, 0–7 T) range. The quality factor (Q{sub L}) exceeds 10{sup 4} below 55 K and it slightly decreases for increasing fields, remaining 90% of Q{sub L}(B=0) for B = 7 T and T = 2 K. These features allow the coherent coupling of resonant photons with a spin ensemble at finite temperature and magnetic field. To demonstrate this, collective strong coupling was achieved by using di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium organic radical placed at the magnetic antinode of the fundamental mode: the in-plane magnetic field is used to tune the spin frequency gap splitting across the single-mode cavity resonance at 7.75 GHz, where clear anticrossings are observed with a splitting as large as ∼82 MHz at T = 2 K. The spin-cavity collective coupling rate is shown to scale as the square root of the number of active spins in the ensemble.
Energy Technology Data Exchange (ETDEWEB)
Min, Shixiong, E-mail: sxmin@nun.edu.cn [School of Chemistry and Chemical Engineering, Beifang University of Nationalities, Yinchuan, 750021, Ningxia Province (China); Hou, Jianhua; Lei, Yonggang; Ma, Xiaohua [School of Chemistry and Chemical Engineering, Beifang University of Nationalities, Yinchuan, 750021, Ningxia Province (China); Lu, Gongxuan [State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China)
2017-02-28
Highlights: • TiO{sub 2}/GQDs composites were prepared by a facile one-step hydrothermal method. • GQDs were strongly coupled onto the surface of TiO{sub 2} nanoparticles by this method. • The TiO{sub 2}/GQDs showed enhanced light absorption and charge separation efficiency. • The TiO{sub 2}/GQDs exhibited higher photocatalytic H{sub 2} evolution activity than pure TiO{sub 2}. • GQDs play synergistic roles by acting as both photosensitizer and electron acceptor. - Abstract: The coupling of semiconductor photocatalysts with graphene quantum dots (GQDs) has been proven to be an effective strategy to enhance the photocatalytic and photoelectrical conversion performances of the resulted composites; however, the preparation of semiconductor/GQDs composites usually involves several time-inefficient and tedious post-treatment steps. Herein, we present a facile one-step hydrothermal route for the preparation of GQDs coupled TiO{sub 2} (TiO{sub 2}/GQDs) photocatalysts using 1,3,6-trinitropyrene (TNP) as the sole precursor of GQDs. During the hydrothermal process, TNP molecules undergo an intramolecular fusion to form GQDs, which simultaneously decorate on the surface of TiO{sub 2} nanoparticles, leading to a strong surface interaction between the two components. The effective coupling of GQDs on TiO{sub 2} can effectively extend the light absorption of the TiO{sub 2} to visible region and enhance the charge separation efficiency of TiO{sub 2}/GQDs composites as a result of GQDs acting as a photosensitizer and an excellent electron acceptor. These key advances make the TiO{sub 2}/GQDs photocatalyst highly active towards the H{sub 2} evolution reaction, resulting in 7 and 3 times higher H{sub 2} evolution rate and photocurrent response at optimal GQDs content than TiO{sub 2} alone, respectively. This study provides a new methodology for the development of high-performance GQDs modified semiconductor photocatalysts for energy conversion applications.
Stimulated Superconductivity at Strong Coupling
Energy Technology Data Exchange (ETDEWEB)
Bao, Ning; Dong, Xi; Silverstein, Eva; Torroba, Gonzalo; /Stanford U., ITP /Stanford U., Phys. Dept. /SLAC
2011-08-12
Stimulating a system with time dependent sources can enhance instabilities, thus increasing the critical temperature at which the system transitions to interesting low-temperature phases such as superconductivity or superfluidity. After reviewing this phenomenon in non-equilibrium BCS theory (and its marginal fermi liquid generalization) we analyze the effect in holographic superconductors. We exhibit a simple regime in which the transition temperature increases parametrically as we increase the frequency of the time-dependent source.
Correlation effects in side-coupled quantum dots
International Nuclear Information System (INIS)
Zitko, R; Bonca, J
2007-01-01
Using Wilson's numerical renormalization group (NRG) technique, we compute zero-bias conductance and various correlation functions of a double quantum dot (DQD) system. We present different regimes within a phase diagram of the DQD system. By introducing a negative Hubbard U on one of the quantum dots, we simulate the effect of electron-phonon coupling and explore the properties of the coexisting spin and charge Kondo state. In a triple quantum dot (TQD) system, a multi-stage Kondo effect appears where localized moments on quantum dots are screened successively at exponentially distinct Kondo temperatures
Small, David W; Head-Gordon, Martin
2017-07-14
The Coupled Cluster Valence Bond (CCVB) method, previously presented for closed-shell (CS) systems, is extended to open-shell (OS) systems. The theoretical development is based on embedding the basic OS CCVB wavefunction in a fictitious singlet super-system. This approach reveals that the OS CCVB amplitude equations are quite similar to those of CS CCVB, and thus that OS CCVB requires the same level of computational effort as CS CCVB, which is an inexpensive method. We present qualitatively correct CCVB potential energy curves for all low-lying spin states of P 2 and Mn 2 + . CCVB is successfully applied to the low-lying spin states of some model linear polycarbenes, systems that appear to be a hindrance to standard density functionals. We examine an octa-carbene dimer in a side-by-side orientation, which, in the monomer dissociation limit, exhibits maximal strong correlation over the length of the polycarbene.
Energy Technology Data Exchange (ETDEWEB)
Abbiendi, G.; Braibant, S.; Capiluppi, P.; Ciocca, C.; Cuffiani, M.; Fabbri, F.; Giacomelli, G.; Giacomelli, P.; Marcellini, S.; Michelini, A.; Rossi, A.M. [Universita di Bologna and INFN, Dipartimento di Fisica, Bologna (Italy); Ainsley, C.; Batley, R.J.; Carter, J.R.; Hill, J.C.; Thomson, M.A.; Ward, C.P.; Ward, D.R. [Cavendish Laboratory, Cambridge (United Kingdom); Aakesson, P.F.; Geich-Gimbel, C.; Guenther, P.O.; Kobel, M.; Ludwig, A.; Mader, W.; Quadt, A.; Schumacher, M.; Stahl, A.; Wermes, N. [Universitaet Bonn, Physikalisches Institut, Bonn (Germany); Alexander, G.; Bella, G.; Etzion, E.; Grunhaus, J.; Tsur, E. [Tel Aviv University, Department of Physics and Astronomy, Tel Aviv (Israel); Anagnostou, G.; Bell, P.J.; Charlton, D.G.; Hawkes, C.M.; Jovanovic, P.; Letts, J.; Maettig, P.; O' Neale, S.W.; Turner-Watson, M.F.; Watkins, P.M.; Watson, A.T.; Watson, N.K.; Wilson, J.A. [University of Birmingham, School of Physics and Astronomy, Birmingham (United Kingdom); Anderson, K.J.; Gupta, A.; Merritt, F.S.; Oreglia, M.J.; Pilcher, J.E.; Spano, F.; Teuscher, R. [University of Chicago, Enrico Fermi Institute and Department of Physics, Chicago, IL (United States); Asai, S.; Ishii, K.; Kanzaki, J.; Kawagoe, K.; Kawamoto, T.; Kobayashi, T.; Komamiya, S.; Mashimo, T.; Mihara, S.; Mori, T.; Nakamura, I.; Nanjo, H.; Orito, S.; Saeki, T.; Toya, D.; Ueda, I.; Yamashita, S. [University of Tokyo, International Centre for Elementary Particle Physics and Department of Physics, Tokyo (Japan); Axen, D.; Lu, J.; McKenna, J. [University of British Columbia, Department of Physics, Vancouver, BC (Canada); Bailey, I.; Karlen, D.; Keeler, R.K.; McPherson, R.A.; Roney, J.M.; Sobie, R. [University of Victoria, Department of Physics, P.O.Box 3055, Victoria, BC (Canada); Barberio, E.; Burckhart, H.J.; De Roeck, A.; De Wolf, E.A.; Ferrari, P.; Frey, A.; Gruwe, M.; Hauschild, M.; Hawkings, R.; Meijers, F.; Oh, A.; Plane, D.E.; Przybycien, M.; Rabbertz, K. [and others
2006-08-15
Data from e{sup +}e{sup -} annihilation into hadrons at centre-of-mass energies between 91 GeV and 209 GeV collected with the OPAL detector at LEP, are used to study the four-jet rate as a function of the Durham algorithm resolution parameter y{sub cut}. The four-jet rate is compared to next-to-leading order calculations that include the resummation of large logarithms. The strong coupling measured from the four-jet rate is {alpha}{sub S(M{sub Z}{sub 0})}=0.1182{+-}0.0003(stat.){+-}0.0015(exp.) {+-}0.0011(had.){+-}0.0012(scale){+-}0.0013(mass), in agreement with the world average. Next-to-leading order fits to the D-parameter and thrust minor event-shape observables are also performed for the first time. We find consistent results, but with significantly larger theoretical uncertainties. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Klijnsma, Thomas; Dissertori, Guenther [ETH Zurich, Institute for Particle Physics, Zurich (Switzerland); Bethke, Siegfried [Max-Planck-Institute of Physics, Munich (Germany); Salam, Gavin P. [CERN, Theoretical Physics Department, Geneva (Switzerland); CNRS, UMR 7589, LPTHE, Paris (France)
2017-11-15
We present a determination of the strong coupling constant α{sub s} (m{sub Z}) using inclusive top-quark pair production cross section measurements performed at the LHC and at the Tevatron. Following a procedure first applied by the CMS Collaboration, we extract individual values of α{sub s} (m{sub Z}) from measurements by different experiments at several centre-of-mass energies, using QCD predictions complete in NNLO perturbation theory, supplemented with NNLL approximations to all orders, and suitable sets of parton distribution functions. The determinations are then combined using a likelihood-based approach, where special emphasis is put on a consistent treatment of theoretical uncertainties and of correlations between various sources of systematic uncertainties. Our final combined result is α{sub s} (m{sub Z}) = 0.1177{sup +0.0034}{sub -0.0036}. (orig.)