All-diode-laser cooling of Sr+ isotope ions for analytical applications
Jung, Kyunghun; Yamamoto, Kazuhiro; Yamamoto, Yuta; Miyabe, Masabumi; Wakaida, Ikuo; Hasegawa, Shuichi
2017-06-01
Trapping and cooling of Sr+ isotope ions by an all-diode-laser system has been demonstrated in order to develop a novel mass spectrometric technique in combination with ion trap-laser cooling. First, we constructed external cavity diode lasers and associated stabilization apparatus for laser cooling of Sr+ ions. The transition frequencies confirmed by optogalvanic spectroscopy enabled successful cooling of 88Sr+ ions. An image of two trapped ions has been captured by CCD camera. Minor isotopes, 84Sr+ and 86Sr+, were also cooled and trapped. From an analysis of the observed spectra of a string crystal of each isotope, the isotope shifts of the cooling transition (5s 2S1/2 → 5p 2P1/2) of Sr+ ions were determined to be +371(8) MHz for Δν84-88 and +169(8) MHz for Δν86-88. In the case of the repumping transition (4d 2D3/2 → 5p 2P1/2), Δν84-88 and Δν86-88 were measured to be -833(6) and -400(5) MHz, respectively. These values are in good agreement with previously reported values.
Sievers, Franz; Kretzschmar, Norman; Fernandes, Diogo Rio; Suchet, Daniel; Rabinovic, Michael; Parker, Colin V; Khaykovich, Lev; Salomon, Christophe; Chevy, Frédéric
2014-01-01
We report on simultaneous sub-Doppler laser cooling of fermionic $^6$Li and $^{40}$K using the D$_1$ optical transitions. We compare experimental results to a numerical simulation of the cooling process applying a semi-classical Monte Carlo wavefunction method. The simulation takes into account the three dimensional optical molasses setup and the dipole interaction between atoms and the bichromatic light field driving the D$_1$ transitions. We discuss the physical mechanisms at play, we identify the important role of coherences between the ground state hyperfine levels and compare D$_1$ and D$_2$ sub-Doppler cooling. In 5 ms, the D$_1$ molasses phase largely reduces the temperature for both $^6$Li and $^{40}$K at the same time, with a final temperature of 44 $\\mu$K and 11 $\\mu$K, respectively. For both species this leads to a phase-space density close to $10^{-4}$. These conditions are well suited to directly load an optical or magnetic trap for efficient evaporative cooling to quantum degeneracy.
Nemova, Galina
2009-01-01
Parallel to advances in laser cooling of atoms and ions in dilute gas phase, which has progressed immensely, resulting in physics Nobel prizes in 1997 and 2001, major progress has recently been made in laser cooling of solids. I compare the physical nature of the laser cooling of atoms and ions with that of the laser cooling of solids. I point out all advantages of this new and very promising area of laser physics. Laser cooling of solids (optical refrigeration) at the present time can be lar...
Energy Technology Data Exchange (ETDEWEB)
Epstein, Richard I [Los Alamos National Laboratory; Sheik-bahae, Mansoor [UNM
2008-01-01
We present an overview of solid-state optical refrigeration also known as laser cooling in solids by fluorescence upconversion. The idea of cooling a solid-state optical material by simply shining a laser beam onto it may sound counter intuitive but is rapidly becoming a promising technology for future cryocooler. We chart the evolution of this science in rare-earth doped solids and semiconductors.
2009-01-01
observed in a range of glasses and crystals doped with Yb3+ (ZBLANP [19–22], ZBLAN [23,24], CNBZn [9,25] BIG [25, 26], KGd(WO4)2 [9], KY(WO4)2 [9], YAG [27...Yb3+-doped fluorozirconate glass ZBLAN , Phys. Rev. B 75, 144302 (2007). [40] C. W. Hoyt, Laser Cooling in Thulium-doped Solids, Ph. D. Thesis...date, optical refrigeration research has been confined to glasses and crystals doped with rare- earth elements and direct-band semiconductors such as
Laser Cooling of Molecular Anions
Yzombard, Pauline; Gerber, Sebastian; Doser, Michael; Comparat, Daniel
2015-01-01
We propose a scheme for laser cooling of negatively charged molecules. We briefly summarise the requirements for such laser cooling and we identify a number of potential candidates. A detailed computation study with C$\\_2^-$, the most studied molecular anion, is carried out. Simulations of 3D laser cooling in a gas phase show that this molecule could be cooled down to below 1 mK in only a few tens of milliseconds, using standard lasers. Sisyphus cooling, where no photo-detachment process is present, as well as Doppler laser cooling of trapped C$\\_2^-$, are also simulated. This cooling scheme has an impact on the study of cold molecules, molecular anions, charged particle sources and antimatter physics.
Laser cooling of molecular anions.
Yzombard, Pauline; Hamamda, Mehdi; Gerber, Sebastian; Doser, Michael; Comparat, Daniel
2015-05-29
We propose a scheme for laser cooling of negatively charged molecules. We briefly summarize the requirements for such laser cooling and we identify a number of potential candidates. A detailed computation study with C_{2}^{-}, the most studied molecular anion, is carried out. Simulations of 3D laser cooling in a gas phase show that this molecule could be cooled down to below 1 mK in only a few tens of milliseconds, using standard lasers. Sisyphus cooling, where no photodetachment process is present, as well as Doppler laser cooling of trapped C_{2}^{-}, are also simulated. This cooling scheme has an impact on the study of cold molecules, molecular anions, charged particle sources, and antimatter physics.
Laser cooling to quantum degeneracy.
Stellmer, Simon; Pasquiou, Benjamin; Grimm, Rudolf; Schreck, Florian
2013-06-28
We report on Bose-Einstein condensation in a gas of strontium atoms, using laser cooling as the only cooling mechanism. The condensate is formed within a sample that is continuously Doppler cooled to below 1 μK on a narrow-linewidth transition. The critical phase-space density for condensation is reached in a central region of the sample, in which atoms are rendered transparent for laser cooling photons. The density in this region is enhanced by an additional dipole trap potential. Thermal equilibrium between the gas in this central region and the surrounding laser cooled part of the cloud is established by elastic collisions. Condensates of up to 10(5) atoms can be repeatedly formed on a time scale of 100 ms, with prospects for the generation of a continuous atom laser.
Triatomic molecules laser-cooled
2017-06-01
Molecules containing three atoms have been laser-cooled to ultracold temperatures for the first time. John Doyle and colleagues at Harvard University in the US used a technique called Sisyphus cooling to chill an ensemble of about a million strontium-monohydroxide molecules to 750 μK.
Structure of beryllium isotopes in fermionic molecular dynamics
Energy Technology Data Exchange (ETDEWEB)
Torabi, Bahram Ramin
2009-02-16
Modern theoretical nuclear physics faces two major challenges. The first is finding a suitable interaction, which describes the forces between nucleons. The second challenge is the solution of the nuclear many-body problem for a given nucleus while applying a realistic potential. The potential used in the framework of this thesis is based on the Argonne AV18 potential. It was transformed by means of the Unitary Correlation Operator Method (UCOM) to optimize convergence. The usual phenomenological corrections were applied to improve the potential for the Hilbert space used in Fermionic Molecular Dynamics (FMD). FMD is an approach to solve the nuclear many-body problem. It uses a single-particle basis which is a superposition of Gaussian distributions in phase-space. The most simple many-body state is the antisymmetric product of the singleparticle states: a Slater determinant, the so called intrinsic state. This intrinsic state is projected on parity, total angular momentum and a center of mass momentum zero. The Hilbert space is spanned by several of these projected states. The states are obtained by minimizing their energy while demanding certain constraints. The expectation values of Slater determinants, parity projected and additionally total angular momentum projected Slater determinants are used. The states that are relevant in the low energy regime are obtained by diagonalization. The lowest moments of the mass-, proton- or neutron-distribution and the excitation in proton- and neutron-shells of a harmonic oscillator are some of the used constraints. The low energy regime of the Beryllium isotopes with masses 7 to 14 is calculated by using these states. Energies, radii, electromagnetic transitions, magnetic moments and point density distributions of the low lying states are calculated and are presented in this thesis. (orig.)
Heteronuclear collisions between laser-cooled metastable neon atoms
Schütz, Jan; John, Holger; Birkl, Gerhard; 10.1103/PhysRevA.86.022713
2012-01-01
We investigate heteronuclear collisions in isotope mixtures of laser-cooled metastable 3P2 neon. Experiments are performed with spin-polarized atoms in a magnetic trap for all two-isotope combinations of the stable neon isotopes 20Ne, 21Ne, and 22Ne. We determine the rate coefficients for heteronuclear ionizing collisions to beta_{21,20}=(3.9+/-2.7) x 10^{-11} cm^3/s, beta_{22,20}=(2.6+/-0.7) x 10^{-11} cm^3/s, and beta_{21,22}=(3.9+/-1.9) x 10^{-11} cm^3/s. We also study heteronuclear elastic collision processes and give upper bounds for heteronuclear thermal relaxation cross sections. This work significantly extends the limited available experimental data on heteronuclear ionizing collisions for laser-cooled atoms involving one or more rare gas atoms in a metastable state.
Optomechanical laser cooling with mechanical modulations
Bienert, Marc; Barberis-Blostein, Pablo
2014-01-01
We theoretically study the laser cooling of cavity optomechanics when the mechanical resonance frequency and damping depend on time. In the regime of weak optomechanical coupling we extend the theory of laser cooling using an adiabatic approximation. We discuss the modifications of the cooling dynamics and compare it with numerical simulations in a wide range of modulation frequencies.
Knife-edge technique for laser cooling
Institute of Scientific and Technical Information of China (English)
WANG Zhanshan; MA Shanshan; MA Yan; ZHAO Min; LIU Hengbiao
2007-01-01
The transfer characteristics of an atomic beam and the effect of laser were investigated in this paper. In the application of knife-edge technique, the temperature of atoms through laser cooling was measured. Results indicate that,after atoms are emitted from an atomic oven, the longer the atoms move, the worse the distribution of the atomic beam shows, regardless the laser cooling is taken or not. Laser cooling can reduce the transverse velocity of the atomic beam to several orders of magnitude and also increase the uniformity of an atomic beam. Knife-edge technique can measure the temperature of an atomic beam through laser cooling. The measurement accuracy depends on the pixel size of the charge coupled device (CCD), which is used for the fluorescent imaging of the atomic beam. The results are very important for the future experiments of laser cooling.
Laser Cooling of 2-6 Semiconductors
2016-08-12
AFRL-AFOSR-JP-TR-2016-0067 Laser Cooling of II-VI Semiconductors Qihua Xiong NANYANG TECHNOLOGICAL UNIVERSITY Final Report 08/12/2016 DISTRIBUTION A...From - To) 15 May 2013 to 14 May 2016 4. TITLE AND SUBTITLE Laser Cooling of II-VI Semiconductors 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA2386-13-1...13. SUPPLEMENTARY NOTES 14. ABSTRACT The breakthrough of laser cooling in semiconductor has stimulated strong interest in further scaling up towards
Direct frequency comb laser cooling and trapping
Jayich, A M; Campbell, W C
2016-01-01
Continuous wave (CW) lasers are the enabling technology for producing ultracold atoms and molecules through laser cooling and trapping. The resulting pristine samples of slow moving particles are the de facto starting point for both fundamental and applied science when a highly-controlled quantum system is required. Laser cooled atoms have recently led to major advances in quantum information, the search to understand dark energy, quantum chemistry, and quantum sensors. However, CW laser technology currently limits laser cooling and trapping to special types of elements that do not include highly abundant and chemically relevant atoms such as hydrogen, carbon, oxygen, and nitrogen. Here, we demonstrate that Doppler cooling and trapping by optical frequency combs may provide a route to trapped, ultracold atoms whose spectra are not amenable to CW lasers. We laser cool a gas of atoms by driving a two-photon transition with an optical frequency comb, an efficient process to which every comb tooth coherently cont...
A description of odd mass Xe and Te isotopes in the Interacting Boson–Fermion Model
Energy Technology Data Exchange (ETDEWEB)
Abu-Musleh, S. [National Center of Research, Gaza, Palestine (Country Unknown); Phys. Dep., Faculty of Women for Art, Science and Education, Ain Shams University, Cairo (Egypt); Abu-Zeid, H.M. [Phys. Dep., Faculty of Women for Art, Science and Education, Ain Shams University, Cairo (Egypt); Scholten, O. [Kernfysisch Versneller Instituut, University of Groningen, 9747 AA, Groningen (Netherlands)
2014-07-15
Recent interest in spectroscopic factors for single-neutron transfer in low-spin states of the even–odd Xenon {sup 125,127,129.131}Xe and even–odd Tellurium, {sup 123,125,127,129,131}Te isotopes stimulated us to study these isotopes within the framework of the Interacting Boson–Fermion Model. The fermion that is coupled to the system of bosons is taken to be in the positive parity 3s{sub 1/2}, 2d{sub 3/2}, 2d{sub 5/2}, 1g{sub 7/2} and in the negative 1h{sub 11/2} single-particle orbits, the complete 50–82 major shell. The calculated energies of low-spin energy levels of the odd isotopes are found to agree well with the experimental data. Also, B(E2), B(M1) values and spectroscopic factors for single-neutron transfer are calculated and compared with experimental data.
Toward laser cooling of negative lanthanum
Jordan, Elena; Cerchiari, Giovanni; Erlewein, Stefan; Kellerbauer, Alban; UNIC Team
2016-05-01
Anion laser cooling holds the potential to allow the production of ultracold ensembles of any negatively charged species by sympathetic cooling. It is a promising technique for cooling of antiprotons to a few mK and could clear the way for precision measurements on cold antihydrogen. Laser cooling of negative ions has never been achieved, since most species have no bound-bound electric dipole transitions. Negative lanthanum (La-) is one of the few anions with multiple electric dipole transitions. The bound-bound transition from the 3F2e ground state to the 3D1o excited state in La- has been proposed theoretically as a candidate for laser cooling. The potential laser cooling transition was identified using laser photodetachment spectroscopy and its excitation energy was measured. We have studied the aforementioned transition in a beam of La anions by high-resolution laser photodetachment spectroscopy. Seven of the nine expected hyperfine structure transitions have been resolved and the transition cross sections have been estimated from experimental observations. It was found that presently La- is the most promising candidate among the atomic anions. We plan to demonstrate the first direct laser cooling of negative ions in a linear radio frequency trap. We gratefully acknowledge support from the European Research Council (ERC).
Laser cooling of a diatomic molecule
Shuman, E S; DeMille, D
2011-01-01
It has been roughly three decades since laser cooling techniques produced ultracold atoms, leading to rapid advances in a vast array of fields. Unfortunately laser cooling has not yet been extended to molecules because of their complex internal structure. However, this complexity makes molecules potentially useful for many applications. For example, heteronuclear molecules possess permanent electric dipole moments which lead to long-range, tunable, anisotropic dipole-dipole interactions. The combination of the dipole-dipole interaction and the precise control over molecular degrees of freedom possible at ultracold temperatures make ultracold molecules attractive candidates for use in quantum simulation of condensed matter systems and quantum computation. Also ultracold molecules may provide unique opportunities for studying chemical dynamics and for tests of fundamental symmetries. Here we experimentally demonstrate laser cooling of the molecule strontium monofluoride (SrF). Using an optical cycling scheme re...
Laser Cooled Atomic Clocks in Space
Thompson, R. J.; Kohel, J.; Klipstein, W. M.; Seidel, D. J.; Maleki, L.
2000-01-01
The goals of the Glovebox Laser-cooled Atomic Clock Experiment (GLACE) are: (1) first utilization of tunable, frequency-stabilized lasers in space, (2) demonstrate laser cooling and trapping in microgravity, (3) demonstrate longest 'perturbation-free' interaction time for a precision measurement on neutral atoms, (4) Resolve Ramsey fringes 2-10 times narrower than achievable on Earth. The approach taken is: the use of COTS components, and the utilization of prototype hardware from LCAP flight definition experiments. The launch date is scheduled for Oct. 2002. The Microgravity Science Glovebox (MSG) specifications are reviewed, and a picture of the MSG is shown.
Direct laser cooling of the BH molecule
Holland, Darren; Truppe, Stefan; Hendricks, Richard; Sauer, Ben; Tarbutt, Michael
2015-03-01
Ultracold polar molecules are of interest for a variety of applications, including tests of fundamental physics, ultracold chemistry, and simulation of many-body quantum systems. The laser cooling techniques that have been so successful in producing ultracold atoms are difficult to apply to molecules. Recently however, laser cooling has been applied successfully to a few molecular species, and a magneto-optical trap of SrF molecules has now been demonstrated. We have investigated the BH molecule as a candidate for laser cooling. We have produced a molecular beam of BH and have measured the branching ratios for the excited electronic state, A1 Π (v' = 0) , to decay to the various vibrational states of the ground electronic state, X1 Σ . We verify that the branching ratio for the spin-forbidden transition to an intermediate triplet state is inconsequentially small. We measure the frequency of the lowest rotational transition of the X state, and the hyperfine structure in the relevant levels of both the X and A states, and determine the nuclear electric quadrupole and magnetic dipole coupling constants. Our results show that a relatively simple laser cooling scheme can be used to cool, slow and trap BH molecules.
Quantum trajectory pictures of laser cooling
Nienhuis, G.; Kloe, J. de; Straten, P. van der
1997-01-01
We have applied the method of single atom trajectories to study the mechanism behind some cooling schemes in laser cooling. In several cases we recognize the cooling mechanism as being due to a "Sisyphus" process, where the atoms move in a spatially varying light shift potential and are optically pu
Recent advances in laser cooling of solids
Nemova, Galina; Kashyap, Raman
2013-10-01
The recent achievements devoted to cooling of solids with a laser are presented in this paper. We discuss the latest results of traditional laser cooling of solids based on rare earth ions and new techniques based on colloidal lead-salt quantum dots doped in a glass host, laser cooling in Tm3+-doped oxy-fluoride glass ceramic. Relatively short (microsecond) lifetime of the excited level of the PbSe QDs compared to the millisecond lifetime of the excited level of RE ions allows an acceleration of the cooling process and provides an opportunity to use new materials with higher phonon energy as hosts, which are normally considered unsuitable for cooling with RE ions. Another new approach to the laser cooling problem based on super-radiance has been considered in this paper. The advantages of optical refrigeration with rare earth doped semiconductors, in which not only optically active electrons of the 4f shell but the valence and conduction bands of the host material are involved in cooling cycle is discussed. It is shown that involving the valence and conduction bands of the host in the cooling cycle allows the pump wavelength to be shorter than mean fluorescence wavelength. Raman laser cooling of solids as well as observation of spontaneous Brillouin cooling have been presented.
Quantum trajectory pictures of laser cooling
Nienhuis, G.; Kloe, J. de; Straten, P. van der
1997-01-01
We have applied the method of single atom trajectories to study the mechanism behind some cooling schemes in laser cooling. In several cases we recognize the cooling mechanism as being due to a "Sisyphus" process, where the atoms move in a spatially varying light shift potential and are optically
Detailed numerical simulations of laser cooling processes
Ramirez-Serrano, J.; Kohel, J.; Thompson, R.; Yu, N.
2001-01-01
We developed a detailed semiclassical numerical code of the forces applied on atoms in optical and magnetic fields to increase the understanding of the different roles that light, atomic collisions, background pressure, and number of particles play in experiments with laser cooled and trapped atoms.
Laser cooling and trapping of barium
De, Subhadeep
2008-01-01
Laser cooling and trapping of heavy alkaline-earth element barium have been demonstrated for the first time ever. For any possible cycling transition in barium that could provide strong cooling forces, the excited state has a very large branching probability to metastable states. Additional lasers
Laser cooling and trapping of barium
De, Subhadeep
2008-01-01
Laser cooling and trapping of heavy alkaline-earth element barium have been demonstrated for the first time ever. For any possible cycling transition in barium that could provide strong cooling forces, the excited state has a very large branching probability to metastable states. Additional lasers a
Laser Stabilization with Laser Cooled Strontium
DEFF Research Database (Denmark)
Christensen, Bjarke Takashi Røjle
the nonlinear effects from coupling of an optical cavity to laser cooled atoms having a narrow transition linewidth. Here, we have realized such a system where a thermal sample of laser cooled strontium-88 atoms are coupled to an optical cavity. The strontium-88 atoms were probed on the narrow 1S0-3P1 inter......The frequency stability of current state-of-the-art stabilized clock lasers are limited by thermal fluctuations of the ultra-stable optical reference cavities used for their frequency stabilization. In this work, we study the possibilities for surpassing this thermal limit by exploiting......-combination line at 689 nm in a strongly saturated regime. The dynamics of the atomic induced phase shift and absorption of the probe light were experimentally studied in details with the purpose of applications to laser stabilization. The atomic sample temperature was in the mK range which brought this system out...
Laser Cooling of 2-6 Semiconductors
2016-08-12
solar cell component, laser materials and waveguides, in which defect in the materials would impair the performance of related device, such as emission... solar cell , and optically pumped lasers. Recent work also shows that perovskite single crystals possess low trap.-state density and high external...difference, the net laser cooling also need nearly unity external quantum efficiency (EQE) and absorption efficiency according to Sheik-Bahae/Epstein
Laser cooling in semiconductors (Conference Presentation)
Zhang, Jun
2017-06-01
Laser cooling of semiconductor is very important topic in science researches and technological applications. Here we will report our progresses on laser cooling in semiconductors. By using of strong coupling between excitons and longitudinal optical phonons (LOPs), which allows the resonant annihilation of multiple LOPs in luminescence up-conversion processes, we observe a net cooling by about 40 K starting from 290 kelvin with 514-nm pumping and about 15 K starting from100 K with 532-nm pumping in a semiconductor using group-II-VI cadmium sulphide nanobelts. We also discuss the thickness dependence of laser cooing in CdS nanobelts, a concept porotype of semiconductor cryocooler and possibility of laser cooling in II-VI semiconductor family including CdSSe、CdSe, CdSe/ZnTe QDs and bulk CdS et al., Beyond II-VI semiconductor, we will present our recent progress in laser cooling of organic-inorganic perovskite materials, which show a very big cooling power and external quantum efficiency in 3D and 2D case. Further more, we demonstrate a resolved sideband Raman cooling of a specific LO phonon in ZnTe, in which only one specific phonon resonant with exciton can be cooled or heated. In the end, we will discuss the nonlinear anti-Stokes Raman and anti-Stokes photoluminescence upcoversion in very low temperature as low as down to liquid 4.2 K. In this case, the anti-Stokes resonance induces a quadratic power denpendece of anti-Stokes Raman and anti-Stokes PL. We proposed a CARS-like process to explain it. This nonlinear process also provides a possible physics picture of ultra-low temperatures phonon assisted photoluminescence and anti-Stokes Raman process.
Current progress in laser cooling of antihydrogen
Luschevskaya, E V
2014-01-01
We talk about laser cooling methods of $\\bar{H} (H)$ and experimental achievements in this area. The Lyman-$\\alpha$ transition $1S\\rightarrow 2P$ is the most suitable one for this purpose due to small lifetime of $2P$ state and insignificant ionization losses at this wavelength. However the pulsed and continuous laser sources of Lyman-$\\alpha$ wavelength do not have enough power for fast cooling. The absence of powefull sources of Lyman-$\\alpha$ irradiation is a technical problem associated with the complexity of four-wave mixing scheme used for irradiation generation. Another problem of $\\bar{H} (H)$ laser cooling is large recoil energy which prevents cooling to submiliKelvin range by simple methods. The alternative way could be in use of other spectral transitions in (anti)hydrogen, new laser cooling methods or even other cooling schemes such as boofer or sympathetic cooling. In this paper we also discuss the applicability of sympathetic cooling for the antihydrogen case. The exploration of antihydrogen and...
Alternative technique for laser cooling with superradiance
Nemova, Galina; Kashyap, Raman
2011-01-01
We present a theoretical scheme for laser cooling of rare-earth-doped solids with optical superradiance (SR), which is the coherent, sharply directed spontaneous emission of photons by a system of laser-excited rare-earth ions in the solid-state host (glass or crystal). We consider an Yb+-doped ZnF4-BaF2-LaF3-AlF3-NaF (ZBLAN) sample pumped at a wavelength 1015 nm, with a rectangular pulsed source with a power of ˜433 W and a duration of 10 ns. The intensity of the SR is proportional to the square of the number of excited ions. This unique feature of SR permits an increase in the rate of the cooling process in comparison with the traditional laser cooling of the rare-earth-doped solids with anti-Stokes spontaneous incoherent radiation (fluorescence). This scheme overcomes the limitation of using only low phonon energy glasses for laser cooling.
Cold beam of isotopically pure Yb atoms by deflection using 1D-optical molasses
Rathod, K. D.; Singh, P. K.; Natarajan, Vasant
2014-09-01
We demonstrate generation of an isotopically pure beam of laser-cooled Yb atoms by deflection using 1D-optical molasses. Atoms in a collimated thermal beam are first slowed using a Zeeman Slower. They are then subjected to a pair of molasses beams inclined at $45^\\circ$ with respect to the slowed atomic beam. The slowed atoms are deflected and probed at a distance of 160 mm. We demonstrate selective deflection of the bosonic isotope $^{174}$Yb, and the fermionic isotope $^{171}$Yb. Using a transient measurement after the molasses beams are turned on, we find a longitudinal temperature of 41 mK.
Cold beam of isotopically pure Yb atoms by deflection using 1D-optical molasses
Indian Academy of Sciences (India)
K D Rathod; P K Singh; Vasant Natarajan
2014-09-01
We demonstrate the generation of an isotopically pure beam of laser-cooled Yb atoms by deflection using 1D-optical molasses. Atoms in a collimated thermal beam are first slowed using a Zeeman slower. They are then subjected to a pair of molasses beams inclined at 45° with respect to the slowed atomic beam. The slowed atoms are deflected and probed at a distance of 160 mm. We demonstrate the selective deflection of the bosonic isotope 174Yb and the fermionic isotope 171Yb. Using a transient measurement after the molasses beams are turned on, we find a longitudinal temperature of 41 mK.
Laser cooling of a diatomic molecule.
Shuman, E S; Barry, J F; Demille, D
2010-10-14
It has been roughly three decades since laser cooling techniques produced ultracold atoms, leading to rapid advances in a wide array of fields. Laser cooling has not yet been extended to molecules because of their complex internal structure. However, this complexity makes molecules potentially useful for a wide range of applications. For example, heteronuclear molecules possess permanent electric dipole moments that lead to long-range, tunable, anisotropic dipole-dipole interactions. The combination of the dipole-dipole interaction and the precise control over molecular degrees of freedom possible at ultracold temperatures makes ultracold molecules attractive candidates for use in quantum simulations of condensed-matter systems and in quantum computation. Also, ultracold molecules could provide unique opportunities for studying chemical dynamics and for tests of fundamental symmetries. Here we experimentally demonstrate laser cooling of the polar molecule strontium monofluoride (SrF). Using an optical cycling scheme requiring only three lasers, we have observed both Sisyphus and Doppler cooling forces that reduce the transverse temperature of a SrF molecular beam substantially, to a few millikelvin or less. At present, the only technique for producing ultracold molecules is to bind together ultracold alkali atoms through Feshbach resonance or photoassociation. However, proposed applications for ultracold molecules require a variety of molecular energy-level structures (for example unpaired electronic spin, Omega doublets and so on). Our method provides an alternative route to ultracold molecules. In particular, it bridges the gap between ultracold (submillikelvin) temperatures and the ∼1-K temperatures attainable with directly cooled molecules (for example with cryogenic buffer-gas cooling or decelerated supersonic beams). Ultimately, our technique should allow the production of large samples of molecules at ultracold temperatures for species that are chemically
Interferometric laser cooling of atomic rubidium
Dunning, Alexander; Bateman, James; Himsworth, Matthew; Freegarde, Tim
2014-01-01
We report the 1-D cooling of atoms using a velocity-dependent optical force based upon Ramsey matter-wave interferometry. The interferometer is realised with stimulated Raman transitions between ground hyperfine states, and after 12 cycles of the cooling sequence, we observe a reduction in the temperature of a freely moving cloud of magneto-optically cooled $^{85}$Rb atoms from 20 $\\mu$K to 4 $\\mu$K, accompanied in this first demonstration by an acceleration of the centre of mass of the atom cloud. This pulse-based laser cooling technique could in principle be extended to molecules and atoms that lack a closed radiative transition.
Vibrational Spectroscopy of Laser Cooled CaH
2015-10-28
Molecular ions trapped in RF Paul traps and sympathetically- cooled with laser - cooled atomic ions have been shown to be a great platform to measure...Approved for public release; distribution is unlimited. Vibrational Spectroscopy of Laser Cooled CaH+ The views, opinions and/or findings contained in...Angeles, CA 90095 -1406 ABSTRACT Vibrational Spectroscopy of Laser Cooled CaH+ Report Title Cold molecules and molecular ions are leading to a renaissance
Laser Stabilization with Laser Cooled Strontium
DEFF Research Database (Denmark)
Christensen, Bjarke Takashi Røjle
The frequency stability of current state-of-the-art stabilized clock lasers are limited by thermal fluctuations of the ultra-stable optical reference cavities used for their frequency stabilization. In this work, we study the possibilities for surpassing this thermal limit by exploiting the nonli......The frequency stability of current state-of-the-art stabilized clock lasers are limited by thermal fluctuations of the ultra-stable optical reference cavities used for their frequency stabilization. In this work, we study the possibilities for surpassing this thermal limit by exploiting...... the nonlinear effects from coupling of an optical cavity to laser cooled atoms having a narrow transition linewidth. Here, we have realized such a system where a thermal sample of laser cooled strontium-88 atoms are coupled to an optical cavity. The strontium-88 atoms were probed on the narrow 1S0-3P1 inter......-combination line at 689 nm in a strongly saturated regime. The dynamics of the atomic induced phase shift and absorption of the probe light were experimentally studied in details with the purpose of applications to laser stabilization. The atomic sample temperature was in the mK range which brought this system out...
Sisyphus Laser Cooling of a Polyatomic Molecule
Kozyryev, Ivan; Matsuda, Kyle; Augenbraun, Benjamin L; Anderegg, Loic; Sedlack, Alexander P; Doyle, John M
2016-01-01
We perform magnetically-assisted Sisyphus laser cooling of the triatomic free radical strontium monohydroxide (SrOH). This is achieved with principal optical cycling in the rotationally closed $P\\left(N"=1\\right)$ branch of either the $\\tilde{X}^{2}\\Sigma^{+}\\left(000\\right)\\leftrightarrow\\tilde{A}^{2}\\Pi_{1/2}\\left(000\\right)$ or the $\\tilde{X}^{2}\\Sigma^{+}\\left(000\\right)\\leftrightarrow\\tilde{B}^{2}\\Sigma^{+}\\left(000\\right)$ vibronic transitions. Molecules lost into the excited vibrational states during the cooling process are repumped back through the $\\tilde{B}\\left(000\\right)$ state for both the $\\left(100\\right)$ level of the Sr-O stretching mode and the $\\left(02^{0}0\\right)$ level of the bending mode. The transverse temperature of a SrOH molecular beam is reduced in one dimension by two orders of magnitude to $\\sim700\\ {\\rm \\mu K}$. This approach opens a path towards creating a variety of ultracold polyatomic molecules, including much larger ones, by means of direct laser cooling.
Sisyphus Laser Cooling of a Polyatomic Molecule.
Kozyryev, Ivan; Baum, Louis; Matsuda, Kyle; Augenbraun, Benjamin L; Anderegg, Loic; Sedlack, Alexander P; Doyle, John M
2017-04-28
We perform magnetically assisted Sisyphus laser cooling of the triatomic free radical strontium monohydroxide (SrOH). This is achieved with principal optical cycling in the rotationally closed P(N^{''}=1) branch of either the X[over ˜]^{2}Σ^{+}(000)↔A[over ˜]^{2}Π_{1/2}(000) or the X[over ˜]^{2}Σ^{+}(000)↔B[over ˜]^{2}Σ^{+}(000) vibronic transitions. Molecules lost into the excited vibrational states during the cooling process are repumped back through the B[over ˜](000) state for both the (100) level of the Sr-O stretching mode and the (02^{0}0) level of the bending mode. The transverse temperature of a SrOH molecular beam is reduced in one dimension by 2 orders of magnitude to ∼750 μK. This approach opens a path towards creating a variety of ultracold polyatomic molecules by means of direct laser cooling.
Laser-cooling-assisted mass spectrometry
Schneider, Christian; Chen, Kuang; Sullivan, Scott T; Hudson, Eric R
2014-01-01
Mass spectrometry is used in a wide range of scientific disciplines including proteomics, pharmaceutics, forensics, and fundamental physics and chemistry. Given this ubiquity, there is a worldwide effort to improve the efficiency and resolution of mass spectrometers. However, the performance of all techniques is ultimately limited by the initial phase-space distribution of the molecules being analyzed. Here, we dramatically reduce the width of this initial phase-space distribution by sympathetically cooling the input molecules with laser-cooled, co-trapped atomic ions, improving both the mass resolution and detection efficiency of a time-of-flight mass spectrometer by over an order of magnitude. Detailed molecular dynamics simulations verify the technique and aid with evaluating its effectiveness. Our technique appears to be applicable to other types of mass spectrometers.
Laser-Cooling-Assisted Mass Spectrometry
Schneider, Christian; Schowalter, Steven J.; Chen, Kuang; Sullivan, Scott T.; Hudson, Eric R.
2014-09-01
Mass spectrometry is used in a wide range of scientific disciplines including proteomics, pharmaceutics, forensics, and fundamental physics and chemistry. Given this ubiquity, there is a worldwide effort to improve the efficiency and resolution of mass spectrometers. However, the performance of all techniques is ultimately limited by the initial phase-space distribution of the molecules being analyzed. Here, we dramatically reduce the width of this initial phase-space distribution by sympathetically cooling the input molecules with laser-cooled, cotrapped atomic ions, improving both the mass resolution and detection efficiency of a time-of-flight mass spectrometer by over an order of magnitude. Detailed molecular-dynamics simulations verify the technique and aid with evaluating its effectiveness. This technique appears to be applicable to other types of mass spectrometers.
Laser cooling and trapping of ytterbium atoms
Institute of Scientific and Technical Information of China (English)
Xin-ye XU; Wen-li WANG; Qing-hong ZHOU; Guo-hui LI; Hai-ling JIANG; Lin-fang CHEN; Jie YE; Zhi-hong ZHOU; Yin CAI; Hai-yao TANG; Min ZHOU
2009-01-01
The experiments on the laser cooling and trapping of ytterbium atoms are reported, including the two-dimensional transversal cooling, longitudinal velocity Zeeman deceleration, and a magneto-optical trap with a broadband transition at a wavelength of 399 nm. The magnetic field distributions along the axis of a Zeeman slower were measured and in a good agreement with the calculated results. Cold ytterbium atoms were produced with a number of about 107 and a temperature of a few milli-Kelvin.In addition, using a 556-nm laser, the excitations of cold tterbium atoms at 1S0-3p1 transition were observed. The ytterbium atoms will be further cooled in a 556-nm magneto-optical trap and loaded into a three-dimensional optical lattice to make an ytterbium optical clock.
Laser Cooled High-Power Fiber Amplifier
Nemova, Galina
2009-01-01
A theoretical model for laser cooled continuous-wave fiber amplifier is presented. The amplification process takes place in the Tm3+-doped core of the fluoride ZBLAN (ZrF4-BaF2-LaF3-AlF3-NaF) glass fiber. The cooling process takes place in the Yb3+:ZBLAN fiber cladding. It is shown that for each value of the pump power and the amplified signal there is a distribution of the concentration of the Tm3+ along the length of the fiber amplifier, which provides its athermal operation. The influence of a small deviation in the value of the amplified signal on the temperature of the fiber with the fixed distribution of the Tm3+ions in the fiber cladding is investigated.
Proposal for Laser Cooling of Complex Polyatomic Molecules.
Kozyryev, Ivan; Baum, Louis; Matsuda, Kyle; Doyle, John M
2016-11-18
An experimentally feasible strategy for direct laser cooling of polyatomic molecules with six or more atoms is presented. Our approach relies on the attachment of a metal atom to a complex molecule, where it acts as an active photon cycling site. We describe a laser cooling scheme for alkaline earth monoalkoxide free radicals taking advantage of the phase space compression of a cryogenic buffer-gas beam. Possible applications are presented including laser cooling of chiral molecules and slowing of molecular beams using coherent photon processes. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Trapping fermionic and bosonic helium atoms
Stas, R.J.W.
2005-01-01
This thesis presents experimental and theoretical work performed at the Laser Centre of the Vrije Universiteit in Amsterdam to study laser-cooled metastable triplet helium atoms. Samples containing about 3x10^8 helium atoms-either fermionic helium-3 atoms, bosonic helium-4 atoms or mixtures thereof
Trapping fermionic and bosonic helium atoms
Stas, R.J.W.
2005-01-01
This thesis presents experimental and theoretical work performed at the Laser Centre of the Vrije Universiteit in Amsterdam to study laser-cooled metastable triplet helium atoms. Samples containing about 3x10^8 helium atoms-either fermionic helium-3 atoms, bosonic helium-4 atoms or mixtures thereof
Trapping fermionic and bosonic helium atoms
Stas, R.J.W.
2005-01-01
This thesis presents experimental and theoretical work performed at the Laser Centre of the Vrije Universiteit in Amsterdam to study laser-cooled metastable triplet helium atoms. Samples containing about 3x10^8 helium atoms-either fermionic helium-3 atoms, bosonic helium-4 atoms or mixtures
Laser cooling in solids: advances and prospects
Seletskiy, Denis V.; Epstein, Richard; Sheik-Bahae, Mansoor
2016-09-01
This review discusses the progress and ongoing efforts in optical refrigeration. Optical refrigeration is a process in which phonons are removed from a solid by anti-Stokes fluorescence. The review first summarizes the history of optical refrigeration, noting the success in cooling rare-earth-doped solids to cryogenic temperatures. It then examines in detail a four-level model of rare-earth-based optical refrigeration. This model elucidates the essential roles that the various material parameters, such as the spacing of the energy levels and the radiative quantum efficiency, play in the process of optical refrigeration. The review then describes the experimental techniques for cryogenic optical refrigeration of rare-earth-doped solids employing non-resonant and resonant optical cavities. It then examines the work on laser cooling of semiconductors, emphasizing the differences between optical refrigeration of semiconductors and rare-earth-doped solids and the new challenges and advantages of semiconductors. It then describes the significant experimental results including the observed optical refrigeration of CdS nanostructures. The review concludes by discussing the engineering challenges to the development of practical optical refrigerators, and the potential advantages and uses of these refrigerators.
Energy Technology Data Exchange (ETDEWEB)
Schiffer, J.P.; Hangst, J.S.; Nielsen, J.S. [and others
1995-08-01
In collaboration with the Arhus group, the laser cooling of a beam bunched by an rf electrode was investigated at the ASTRID storage ring. A single laser is used for unidirectional cooling, since the longitudinal velocity of the beam will undergo {open_quotes}synchrotron oscillations{close_quotes} and the ions are trapped in velocity space. As the cooling proceeds the velocity spread of the beam, as well as the bunch length is measured. The bunch length decreases to the point where it is limited only by the Coulomb repulsion between ions. The measured length is slightly (20-30%) smaller than the calculated limit for a cold beam. This may be the accuracy of the measurement, or may indicate that the beam still has a large transverse temperature so that the longitudinal repulsion is less than would be expected from an absolutely cold beam. Simulations suggest that the coupling between transverse and longitudinal degrees of freedom is strong -- but this issue will have to be resolved by further measurements.
Direct laser cooling Al+ ions optical clocks
Zhang, J; Luo, J; Lu, Z H
2016-01-01
Al$^+$ ions optical clock is a very promising optical frequency standard candidate due to its extremely small blackbody radiation shift. It has been successfully demonstrated with indirect cooled, quantum-logic-based spectroscopy technique. Its accuracy is limited by second-order Doppler shift, and its stability is limited by the number of ions that can be probed in quantum logic processing. We propose a direct laser cooling scheme of Al$^+$ ions optical clocks where both the stability and accuracy of the clocks are greatly improved. In the proposed scheme, two Al$^+$ ions traps are utilized. The first trap is used to trap a large number of Al$^+$ ions to improve the stability of the clock laser, while the second trap is used to trap a single Al$^+$ ions to provide the ultimate accuracy. Both traps are cooled with a continuous wave 167 nm laser. The expected clock laser stability can reach $9.0\\times10^{-17}/\\sqrt{\\tau}$. For the second trap, in addition to 167 nm laser Doppler cooling, a second stage pulsed ...
Mechanism of refrigeration cycle on laser cooling of solids
Institute of Scientific and Technical Information of China (English)
Youhua Jia; Biao Zhong; Jianping Yin
2012-01-01
A simple model is developed to study the laser cooling of solids. The condition of laser cooling of a solid is developed. By using some parameters of the Yb3+ ion, which is most widely used in laser cooling, we then calculate the cooling power and the cooling efficiency. In order to make a more precise analysis, the effect of fluorescent reabsorption, which is unavoidable in the cooling process, is discussed using the random walk model. Taking Tm3+ ion as an example, we derive the average number of absorption events and determine the change in quantum efficiency due to reabsorption. Finally, we obtain the red-shift of the fluorescent wavelength and the requirement of sample dimension.%A simple model is developed to study the laser cooling of solids.The condition of laser cooling of a solid is developed.By using some parameters of the Yb3+ ion,which is most widely used in laser cooling,we then calculate the cooling power and the cooling efficiency.In order to make a more precise analysis,the effect of fluorescent reabsorption,which is unavoidable in the cooling process,is discussed using the random walk model.Taking Tm3+ ion as an example,we derive the average number of absorption events and determine the change in quantum efficiency due to reabsorption.Finally,we obtain the red-shift of the fluorescent wavelength and the requirement of sample dimension.
Laser cooling of new atomic and molecular species with ultrafast pulses
Kielpinski, David
2005-01-01
We propose a new laser cooling method for atomic species whose level structure makes traditional laser cooling difficult. For instance, laser cooling of hydrogen requires single-frequency vacuum-ultraviolet light, while multielectron atoms need single-frequency light at many widely separated frequencies. These restrictions can be eased by laser cooling on two-photon transitions with ultrafast pulse trains. Laser cooling of hydrogen, antihydrogen, and many other species appears feasible, and e...
One single trapped and laser cooled radium ion: Towards an all-optical atomic clock
Energy Technology Data Exchange (ETDEWEB)
Versolato, Oscar; Wansbeek, Lotje; Willmann, Lorenz; Timmermans, Rob; Jungmann, Klaus [KVI, University of Groningen (Netherlands)
2008-07-01
One single trapped radium ion is an ideal candidate for an all-optical frequency standard (*clock*). This system provides a long coherence time and tractable systematics. If the ion is laser cooled to the Lamb-Dicke regime, first order Doppler shifts are eliminated. Ultra-narrow transitions in radium ions provide an excellent basis for such a high stability clock, using commercially available semiconductor lasers in the visible regime. In certain odd isotopes of radium, the nuclear electric quadrupole shift is absent. Further, the radium ion is an excellent candidate for a high sensitivity experiment to search for a time variation of the finestructure constant.
A new technique for laser cooling with superradiance
Nemova, Galina
2010-01-01
We present a new theoretical scheme for laser cooling of rare earth doped solids with optical super-radiance (SR), which is the coherent, sharply directed spontaneous emission of photons by a system of laser excited rare earth ions in the solid state host (glass or crystal). We consider an Yb3+ doped ZBLAN sample pumped at the wavelength 1015 nm with a rectangular pulsed source with a power of ~433W and duration of 10ns. The intensity of the SR is proportional to the square of the number of excited ions. This unique feature of SR permits a dramatic increase in the rate of the cooling process in comparison with the traditional laser cooling of the rare earth doped solids with anti-Stokes spontaneous incoherent radiation (fluorescence). This scheme overcomes the limitation of using only low phonon energy hosts for laser cooling.
Longitudinal dynamics of laser-cooled fast ion beams
DEFF Research Database (Denmark)
Weidemüller, M.; Eike, B.; Eisenbarth, U.
1999-01-01
We present recent results of our experiments on laser cooling of fast stored ion beams at the Heidelberg Test Storage Ring. The longitudinal motion of the ions is directly cooled by the light pressure force, whereas efficient transverse cooling is obtained indirectly by longitudinal......-transverse coupling mechanisms. Laser cooling in novel bunch forms consisting of square-well buckets leads to longitudinally space-charge dominated beams. The observed longitudinal ion density distributions can be well described by a self-consistent mean-field model based on a thermodynamic Debye-Huckel approach....... When applying laser cooling in square-well buckets over long time intervals, hard Coulomb collisions suddenly disappear and the longitudinal temperature drops by about a factor of three. The observed longitudinal behaviour of the beam shows strong resemblance with the transition to an Coulomb...
Laser Cooling of Lanthanides: from Optical Clocks to Quantum Simulators
Directory of Open Access Journals (Sweden)
Golovizin A.
2015-01-01
Full Text Available We discuss current progress in laser cooling of lanthanides (Er, Yb, Dy, Tm etc. focusing on applications. We describe some important peculiarities taking Thulium atom as an example: Two stage laser cooling, trapping in an optical lattice, anisotropic interactions and spectroscopy of narrow transitions. Specific level structure and presence of magic wavelengths make ultracold Thulium a favorable candidate for optical clock applications. On the other hand, abundance of Feshbach resonances allow to tune interactions in ultracold gases and thus reach quantum degeneracy. It opens intriguing perspectives for novel quantum simulators employing dipole-dipole interactions in an optical lattice.
Continuous-wave, single-frequency 229 nm laser source for laser cooling of cadmium atoms
Kaneda, Yushi; Merzlyak, Yevgeny; Yamaguchi, Atsushi; Hayashida, Keitaro; Ohmae, Noriaki; Katori, Hidetoshi
2016-01-01
Continuous-wave output at 229 nm for the application of laser cooling of Cd atoms was generated by the 4th harmonic using two successive second harmonic generation stages. Employing a single-frequency optically pumped semiconductor laser as a fundamental source, 0.56 W of output at 229 nm was observed with a 10-mm long, Brewster-cut BBO crystal in an external cavity with 1.62 W of 458 nm input. Conversion efficiency from 458 nm to 229 nm was more than 34%. By applying a tapered amplifier as a fundamental source, we demonstrated magneto-optical trapping of all stable Cd isotopes including isotopes $^{111}$Cd and $^{113}$Cd, which are applicable to optical lattice clocks.
Laser-cooling simulation based on the semiclassical approach
Smeets, B.; Herfst, R.W.; Sligte, E. te; Straten, van der P.; Beijerinck, H.C.W.; Leeuwen, van K.A.H.
2005-01-01
We investigate the region of validity of the semiclassical approach to simulating laser cooling. We conclude that for the commonly used pi(x) pi(y) polarization-gradient configuration, the semiclassical approach is valid only for transitions with recoil parameters epsilon(r), on the order of 10(-4)
Simulations Of Laser Cooling In An Ultracold Neutral Plasma
Langin, Thomas; Strickler, Trevor; Pohl, Thomas; Vrinceanu, Daniel; Killian, Thomas
2016-05-01
Ultracold neutral plasmas (UNPs) generated by photoionization of laser-cooled, magneto-optically trapped neutral gases, are useful systems for studying strongly coupled plasmas. Coupling is parameterized by Γi, the ratio of the average nearest neighbor Coulomb interaction energy to the ion kinetic energy. For typical UNPs, Γi is currently limited to ~ 3 . For alkaline earth ions, higher Γi can be achieved by laser-cooling. Using Molecular Dynamics and a quantum trajectories approach, we have simulated laser-cooling of Sr+ ions interacting through a Yukawa potential. The simulations include re-pumping from two long-lived D-states, and are conducted at experimentally achievable parameters (density n = 2 e+14 m-3, size σ0 = 4 mm, Te = 19 K). Laser-cooling is shown to both reduce the temperature by a factor of 2 over relevant timescales (tens of μ s) and slow the electron thermal-pressure driven radial expansion of the UNP. We also discuss the unique aspects of laser-cooling in a highly collisional system; in particular, the effect of collisions on dark state formation due to the coupling of the P3/2 state to both the S1/2 (via the cooling transition) and the D5/2 (via a re-pump transition) states. Supported by NSF and DoE, the Air Force Office of Scientific Research, the NDSEG Program, and NIH NCRR S10RR02950, an IBM SUR Award in partnership with CISCO, Qlogic and Adaptive Computing.
Nagaoka ferromagnetism in large-spin fermionic and bosonic systems
Miyashita, Seiji; Ogata, Masao; De Raedt, Hans
2009-01-01
We study the magnetic properties of itinerant quantum magnetic particles, described by a generalized Hubbard model with large spin (S>1/2), which may be realized in optical lattices of laser-cooled atom systems. In fermion systems (half-integer spins), an extended form of Nagaoka ferromagnetism may
Nagaoka ferromagnetism in large-spin fermionic and bosonic systems
Miyashita, Seiji; Ogata, Masao; De Raedt, Hans
2009-01-01
We study the magnetic properties of itinerant quantum magnetic particles, described by a generalized Hubbard model with large spin (S>1/2), which may be realized in optical lattices of laser-cooled atom systems. In fermion systems (half-integer spins), an extended form of Nagaoka ferromagnetism may
Raman Sideband Cooling of Two-Valence-Electron Fermionic Atoms
Institute of Scientific and Technical Information of China (English)
LI Guo-Hui; XU Xin-Ye
2011-01-01
We propose a method for laser cooling two-valence-electron fermionic atoms. Our protocol employs resolved-sideband cooling on the stimulated Raman transition between the two magnetic sublevels (m = F and m = F - 1) of the ground state with total anguiar momentum F. The optical pumping from m = F - 1 to 1 Pi are used to decouple atoms in the m = F - 1 state. We calculate the Raman coupling generated by an engineered optical lattice. The result shows that it is possible to laser cool the two-valence-electron fermionic atoms to the ground state. The atoms in the ground state provide a new system for quantum optics.%@@ We propose a method for laser cooling two-valence-electron fermionic atoms.Our protocol employs resolved- sideband cooling on the stimulated Raman transition between the two magnetic sublevels (m=F and m = F- 1) of the ground state with total angular momentum F.The optical pumping from m = F - 1 to p are used to decouple atoms in the m = F - 1 state.We calculate the Raman coupling generated by an engineered optical lattice.The result shows that it is possible to laser cool the two-valence-electron fermionic atoms to the ground state.The atoms in the ground state provide a new system for quantum optics.
Laser cooling of a semiconductor by 40 kelvin.
Zhang, Jun; Li, Dehui; Chen, Renjie; Xiong, Qihua
2013-01-24
Optical irradiation accompanied by spontaneous anti-Stokes emission can lead to cooling of matter, in a phenomenon known as laser cooling, or optical refrigeration, which was proposed by Pringsheim in 1929. In gaseous matter, an extremely low temperature can be obtained in diluted atomic gases by Doppler cooling, and laser cooling of ultradense gas has been demonstrated by collisional redistribution of radiation. In solid-state materials, laser cooling is achieved by the annihilation of phonons, which are quanta of lattice vibrations, during anti-Stokes luminescence. Since the first experimental demonstration in glasses doped with rare-earth metals, considerable progress has been made, particularly in ytterbium-doped glasses or crystals: recently a record was set of cooling to about 110 kelvin from the ambient temperature, surpassing the thermoelectric Peltier cooler. It would be interesting to realize laser cooling in semiconductors, in which excitonic resonances dominate, rather than in systems doped with rare-earth metals, where atomic resonances dominate. However, so far no net cooling in semiconductors has been achieved despite much experimental and theoretical work, mainly on group-III-V gallium arsenide quantum wells. Here we report a net cooling by about 40 kelvin in a semiconductor using group-II-VI cadmium sulphide nanoribbons, or nanobelts, starting from 290 kelvin. We use a pump laser with a wavelength of 514 nanometres, and obtain an estimated cooling efficiency of about 1.3 per cent and an estimated cooling power of 180 microwatts. At 100 kelvin, 532-nm pumping leads to a net cooling of about 15 kelvin with a cooling efficiency of about 2.0 per cent. We attribute the net laser cooling in cadmium sulphide nanobelts to strong coupling between excitons and longitudinal optical phonons (LOPs), which allows the resonant annihilation of multiple LOPs in luminescence up-conversion processes, high external quantum efficiency and negligible background
BaH molecular spectroscopy with relevance to laser cooling
Tarallo, M. G.; Iwata, G. Z.; Zelevinsky, T.
2016-03-01
We describe a simple experimental apparatus for laser ablation of barium monohydride (BaH) molecules and the study of their rovibrational spectra relevant to direct laser cooling. BaH is a promising candidate for laser cooling and ultracold fragmentation, both of which are precursors to novel experiments in many-body physics and precision measurement. We present a detailed analysis of the properties of ablation plumes that can improve the understanding of surface ablation and deposition technologies. A range of absorption spectroscopy and collisional thermalization regimes has been studied. We directly measured the Franck-Condon factor of the B 2Σ+(v'=0 ) ←X 2Σ+(v''=1 ) cycling transition. Prospects for production of a high luminosity cryogenic BaH beam are outlined.
BaH molecular spectroscopy with relevance to laser cooling
Tarallo, M G; Zelevinsky, T
2015-01-01
We describe a simple experimental apparatus for laser ablation of barium monohydride (BaH) molecules and the study of their rovibrational spectra that are relevant to direct laser cooling. We present a detailed analysis of the properties of ablation plumes that can improve the understanding of surface ablation and deposition technologies. A range of absorption spectroscopy and collisional thermalization regimes has been studied. We directly measured the Franck-Condon factor of the $\\mathrm{B}^2\\Sigma^+(v'=0)\\leftarrow\\mathrm{X}^2\\Sigma^+(v"=1)$ transition. Prospects for production of a high luminosity cryogenic BaH beam are outlined. This molecule is a promising candidate for laser cooling and ultracold fragmentation, both of which are precursors to novel experiments in many-body physics and precision measurement.
Sub-Doppler Laser Cooling using Electromagnetically Induced Transparency
He, Peiru; Anderson, Dana Z; Rey, Ana Maria; Holland, Murray
2016-01-01
We propose a sub-Doppler laser cooling mechanism that takes advantage of the unique spectral features and extreme dispersion generated by the phenomenon of electromagnetically induced transparency (EIT). EIT is a destructive quantum interference phenomenon experienced by atoms with multiple internal quantum states when illuminated by laser fields with appropriate frequencies. By detuning the lasers slightly from the "dark resonance", we observe that, within the transparency window, atoms can be subject to a strong viscous force, while being only slightly heated by the diffusion caused by spontaneous photon scattering. In contrast to other laser cooling schemes, such as polarization gradient cooling or EIT-sideband cooling, no external magnetic field or strong external confining potential is required. Using a semiclassical approximation, we derive analytically quantitative expressions for the steady-state temperature, which is confirmed by full quantum mechanical numerical simulations. We find that the lowest ...
On-chip optical detection of laser cooled atoms.
Quinto-Su, P; Tscherneck, M; Holmes, M; Bigelow, N
2004-10-18
We have used an optical fiber based system to implement optical detection of atoms trapped on a reflective "atom-chip". A fiber pair forms an emitter-detector setup that is bonded to the atom-chip surface to optically detect and probe laser cooled atoms trapped in a surface magneto-optical trap. We demonstrate the utility of this scheme by measuring the linewidth of the Cs D2 line at different laser intensities.
Proposal for Laser Cooling of Alkaline Earth Monoalkoxide Free Radicals
Baum, Louis; Kozyryev, Ivan; Matsuda, Kyle; Doyle, John M.
2016-05-01
Cold samples of polyatomic molecules will open new avenues in physics, chemistry, and quantum science. Non-diagonal Franck-Condon factors, technically challenging wavelengths, and the lack of strong electronic transitions inhibit direct laser cooling of nonlinear molecules. We identify a scheme for optical cycling in certain molecules with six or more atoms. Replacing hydrogen in alcohols with an alkaline earth metal (M) leads to alkaline earth monoalkoxide free radicals (MOR), which have favorable properties for laser cooling. M-O bond is very ionic, so the metal orbitals are slightly affected by the nature of R on the ligand. Diagonal Franck-Condon factors, laser accessible transitions, and a small hyperfine structure make MOR molecules suitable for laser cooling. We explore a scheme for optical cycling on the A - X transition of SrOCH3 . Molecules lost to dark vibrational states will be repumped on the B - X transition. Extension to larger species is possible through expansion of the R group since transitions involve the promotion of the metal-centered nonbonding valence electron. We will detail our estimations of the Franck-Condon factors, simulations of the cooling process and describe progress towards the Doppler cooling of MOR polyatomics.
Ion microscopy based on laser-cooled cesium atoms
Energy Technology Data Exchange (ETDEWEB)
Viteau, M.; Reveillard, M.; Kime, L.; Rasser, B.; Sudraud, P. [Orsay Physics, TESCAN Orsay, 95 Avenue des Monts Auréliens – ZA Saint-Charles – 13710 Fuveau (France); Bruneau, Y.; Khalili, G.; Pillet, P.; Comparat, D. [Laboratoire Aimé Cotton, CNRS, Université Paris-Sud, ENS Cachan, Bât. 505, 91405 Orsay (France); Guerri, I. [Dipartimento di Fisica, Università di Pisa, Largo Pontecorvo 3, 56127 Pisa (Italy); Fioretti, A., E-mail: andrea.fioretti@ino.it [Istituto Nazionale di Ottica, INO-CNR, U.O.S. ”Adriano Gozzini”, via Moruzzi 1, 56124 Pisa (Italy); Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, CNISM, Sezione di Pisa, 56127 Pisa (Italy); Ciampini, D.; Allegrini, M.; Fuso, F. [Dipartimento di Fisica, Università di Pisa, Largo Pontecorvo 3, 56127 Pisa (Italy); Istituto Nazionale di Ottica, INO-CNR, U.O.S. ”Adriano Gozzini”, via Moruzzi 1, 56124 Pisa (Italy); Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, CNISM, Sezione di Pisa, 56127 Pisa (Italy)
2016-05-15
We demonstrate a prototype of a Focused Ion Beam machine based on the ionization of a laser-cooled cesium beam and adapted for imaging and modifying different surfaces in the few-tens nanometer range. Efficient atomic ionization is obtained by laser promoting ground-state atoms into a target excited Rydberg state, then field-ionizing them in an electric field gradient. The method allows obtaining ion currents up to 130 pA. Comparison with the standard direct photo-ionization of the atomic beam shows, in our conditions, a 40-times larger ion yield. Preliminary imaging results at ion energies in the 1–5 keV range are obtained with a resolution around 40 nm, in the present version of the prototype. Our ion beam is expected to be extremely monochromatic, with an energy spread of the order of the eV, offering great prospects for lithography, imaging and surface analysis. - Highlights: • We realize a Focused Ion Beam with an ionic source based on laser cooled cesium atoms. • Ionization involves excitation of the laser cooled atoms to Rydberg states. • We use the cesium FIB system to image different materials. • We use the cesium FIB to produce permanent modifications on surfaces. • In the present configuration, the focused probe size of the cesium FIB prototype is about 300 nm for beam energies in the 2–5 keV range.
Atomic fountain of laser-cooled Yb atoms for precision measurements
Pandey, Kanhaiya; Singh, Alok K; Natarajan, Vasant
2010-01-01
We demonstrate launching of laser-cooled Yb atoms in a cold atomic fountain. Atoms in a collimated thermal beam are first cooled and captured in a magneto-optic trap (MOT) operating on the strongly-allowed ${^1S}_0 \\rightarrow {^1P}_1$ transition at 399~nm (blue line). They are then transferred to a MOT on the weakly-allowed ${^1S}_0 \\rightarrow {^3P}_1$ transition at 556~nm (green line). Cold atoms from the green MOT are launched against gravity at a velocity of around 2.5~m/s using a pair of green beams. We trap more than $10^7$ atoms in the blue MOT and transfer up to 70\\% into the green MOT. The temperature for the odd isotope, $^{171}$Yb, is $\\sim$1~mK in the blue MOT, and reduces by a factor of 40 in the green MOT.
Improvement on Fermionic properties and new isotope production in molecular dynamics simulations
Wang, Ning; Zeng, Jie; Yang, Yongxu; Ou, Li
2016-01-01
By considering momentum transfer in the Fermi constraint procedure, the stability of the initial nuclei and fragments produced in heavy-ion collisions can be further improved in the quantum molecular dynamics simulations. The case of the phase space occupation probability larger than one is effectively reduced with the proposed procedure. Simultaneously, the energy conservation can be better described for both individual nuclei and heavy-ion reactions. With the revised version of the improved quantum molecular dynamics (ImQMD) model, the fusion excitation functions of $^{16}$O+$^{186}$W and the central collisions of Au+Au at 35 AMeV are re-examined. The fusion cross sections at sub-barrier energies and the charge distribution of fragments are relatively better reproduced due to the reduction of spurious nucleon emission. The charge and isotope distribution of fragments in Xe+Sn, U+U and Zr+Sn at intermediate energies are also predicted. More unmeasured extremely neutron-rich fragments with $Z=16-28$ are obser...
Repumping and spectroscopy of laser-cooled Sr atoms using the (5s5p)3P2-(5s4d)3D2 transition
Mickelson, P. G.; Martinez de Escobar, Y. N.; Anzel, P.; De Salvo, B. J.; Nagel, S. B.; Traverso, A. J.; Yan, M.; Killian, T. C.
2009-12-01
We describe repumping and spectroscopy of laser-cooled strontium (Sr) atoms using the (5s5p)3P2-(5s4d)3D2 transition. Atom number in a magneto-optical trap is enhanced by driving this transition because Sr atoms that have decayed into the (5s5p)3P2 dark state are repumped back into the (5s2)1S0 ground state. Spectroscopy of 84Sr, 86Sr, 87Sr and 88Sr improves the value of the (5s5p)3P2-(5s4d)3D2 transition frequency and determines the isotope shifts for the transition accurately enough to guide laser-cooling experiments with less abundant isotopes.
Optical Refrigeration Science and Applications of Laser Cooling of Solids
Epstein, Richard
2009-01-01
Edited by the two top experts in the field with a panel of International contributors, this is a comprehensive up-to-date review of research and applications. Starting with the basic physical principles of laser cooling of solids, the monograph goes on to discuss the current theoretical issues being resolved and the increasing demands of growth and evaluation of high purity materials suitable for optical refrigeration, while also examining the design and applications of practical cryocoolers. An advanced text for scientists, researchers, engineers, and students (masters, PHDs and Postdoc) in l
Advances in Laser Cooling of Thulium-Doped Glass
2003-05-01
conversion,’’ Appl. Phys. Lett. 75, 1258–1260 (1999). 21. L. Wetenkamp, G. F. West, and H. Tobben, ‘‘Optical proper- ties of rare earth-doped ZBLAN glasses ...properties of Tm31 in ZBLAN fluoride glass . Part 2. Judd-Ofelt parameters,’’ Phys. Chem. Glasses 36, 139–140 (1995). 38. M. J. Weber, ‘‘Laser excited...Advances in laser cooling of thulium-doped glass C. W. Hoyt, M. P. Hasselbeck, and M. Sheik-Bahae Department of Physics and Astronomy, University of
Clock Technology Development for the Laser Cooling and Atomic Physics (LCAP) Program
Klipstein, W. M.; Thompson, R. J.; Seidel, D. J.; Kohel, J.; Maleki, L.
1998-01-01
The Time and Frequency Sciences and Technology Group at Jet Propulsion Laboratory (JPL) has developed a laser cooling capability for flight and has been selected by NASA to support the Laser-Cooling and Atomic Physics (LCAP) program. Current work in the group includes design and development for tee two laser-cooled atomic clock experiments which have been selected for flight on the International Space Station.
Sub-Doppler laser cooling using electromagnetically induced transparency
He, Peiru; Tengdin, Phoebe M.; Anderson, Dana Z.; Rey, Ana Maria; Holland, Murray
2017-05-01
We propose a sub-Doppler laser-cooling mechanism that takes advantage of the unique spectral features and extreme dispersion generated by the phenomenon of electromagnetically induced transparency (EIT). EIT is a destructive quantum interference phenomenon experienced by atoms with multiple internal quantum states when illuminated by laser fields with appropriate frequencies. By detuning the lasers slightly from the "dark resonance," we observe that, within the transparency window, atoms can be subject to a strong viscous force, while being only slightly heated by the diffusion caused by spontaneous photon scattering. In contrast to other laser-cooling schemes, such as polarization gradient cooling or EIT-sideband cooling, no external magnetic field or strong external confining potential is required. Using a semiclassical approximation, we derive analytically quantitative expressions for the steady-state temperature, which is confirmed by full quantum mechanical numerical simulations. We find that the lowest achievable temperatures approach the single-photon recoil energy. In addition to dissipative forces, the atoms are subject to a stationary conservative potential, leading to the possibility of spatial confinement. We find that under typical experimental parameters, this effect is weak and stable trapping is not possible.
Laser cooling, slowing and trapping of a diatomic molecule
Barry, John
2015-05-01
Roughly three decades ago, laser cooling and trapping succeeded in producing ultracold ions and atoms, sparking a revolution in atomic physics and subsequently becoming workhorse techniques within the field. These techniques require a ``cycling transition,'' where the particle of interest is repeatedly driven by a photon into an excited electronic state and quickly decays back to the initial ground state, allowing the process to repeat. Because photon absorption transfers momentum to the particle, application of force is possible. Adjusting the geometry and frequency of the applied photons allows creation of a damping (cooling) force. Further addition of a quadrupole magnetic field allows for a restoring (trapping) force. Prior to this thesis, straightforward extension of these methods to molecules was considered a practical impossibility; electronic decays in molecules tend to populate multiple rotational and vibrational states, preventing creation of a cycling transition. While a variety of ultracold molecular species is desirable to satisfy a range of applications, the only other production method is limited to species where the constituent atoms are themselves amenable to laser cooling. For other species, a different technique is required. Here we outline the methods and experiments in which laser cooling and trapping were first applied to molecules. By careful molecule choice, by using a cooling transition that exploits selection rules, and by counteracting dark states with a magnetic field, we create a cycling transition for the diatomic molecule strontium monofluoride (SrF). We show the power of this technique by demonstrating Doppler and sub-Doppler cooling in 1-D, radiation pressure slowing and stopping of a molecular beam, and finally a 3-D magneto-optical trap (MOT). Our MOT produces the coldest trapped sample of directly-cooled molecules to date, with a temperature of T ~ 2.5 mK. This method is viable for several classes of diatomic molecules with a
Laser cooling of a stored ion beam: A first step towards crystalline beams
Energy Technology Data Exchange (ETDEWEB)
Hangst, J.S.
1992-09-01
This report discusses: a brief introduction to storage rings; crystalline beams; laser cooling of ion beams; description of astrid-the experimental setup; first experiments with lithium 7 ion beam; experiments with erbium 166 ion beams; further experiments with lithium 7 ion beams; beam dynamics, laser cooling,and crystalline beams in astrid; possibilities for further study in astrid.
Candidate for laser cooling of a negative ion: observations of bound-bound transitions in La(-).
Walter, C W; Gibson, N D; Matyas, D J; Crocker, C; Dungan, K A; Matola, B R; Rohlén, J
2014-08-08
Despite the tremendous advances in laser cooling of neutral atoms and positive ions, no negatively charged ion has been directly laser cooled. The negative ion of lanthanum, La(-), has been proposed as the best candidate for laser cooling of any atomic anion [ and , Phys. Rev. A 81, 032503 (2010)]. Tunable infrared laser photodetachment spectroscopy is used to measure the bound-state structure of La(-), revealing a spectrum of unprecedented richness with multiple bound-bound electric dipole transitions. The potential laser-cooling transition ((3)F(2)(e)→(3)D(1)(o)) is identified and its excitation energy is measured. The results confirm that La^{-} is a very promising negative ion for laser-cooling applications.
Sympathetic laser cooling of graphene with Casimir-Polder forces
Ribeiro, Sofia; Terças, Hugo
2016-10-01
We propose a scheme to actively cool the fundamental flexural (out-of-plane) mode of a graphene sheet via vacuum forces. Our setup consists of a cold-atom cloud placed close to a graphene sheet at distances of a few micrometers. The atoms couple to the graphene membrane via Casimir-Polder forces. By deriving a self-consistent set of equations governing the dynamics of the atomic gas and the flexural modes of the graphene, we show it is possible to cool graphene from room temperatures by actively (laser) cooling an atomic gas. By choosing the right set of experimental parameters we are able to cool a graphene sheet down to ˜60 μ K .
CW fountain of laser-cooled Yb atoms
Rathod, K D; Natarajan, Vasant
2013-01-01
We demonstrate launching of laser-cooled Yb atoms in a continuous atomic fountain. The continuous fountain has significant advantages over the more common pulsed fountain, which was also demonstrated by us recently. The fountain is formed in the following steps---(i) Atoms from a thermal beam are first Zeeman slowed to a small final velocity, (ii) the slowed atoms are captured in a two-dimensional magneto-optic trap (2D-MOT), and (iii) atoms are launched {\\em continuously} in the vertical direction using two sets of moving-molasses beams, inclined at $\\pm 15^\\circ$ to the vertical. The cooling transition used is the strongly-allowed ${^1S}_0 \\rightarrow {^1P}_1$ transition at 399 nm. We capture about $7 \\times 10^6$ atoms in the 2D-MOT, and then launch them with a vertical velocity of 13 m/s at a longitudinal temperature of 125(6) mK.
Enhancement of laser cooling by the use of magnetic gradients
Energy Technology Data Exchange (ETDEWEB)
Albrecht, A; Retzker, A; Plenio, M B [Institut fuer Theoretische Physik, Universitaet Ulm, 89069 Ulm (Germany); Wunderlich, C, E-mail: andreas.albrecht@uni-ulm.de [Fachbereich Physik, Universitaet Siegen, D-57068 Siegen (Germany)
2011-03-15
We present a laser cooling scheme for trapped ions and atoms using a combination of laser couplings and a magnetic gradient field. In a Schrieffer-Wolff transformed picture, this setup cancels the carrier and blue sideband terms completely (up to first order in the Lamb-Dicke parameter), resulting in an improved cooling behaviour compared to standard cooling schemes in the Lamb-Dicke regime (e.g. sideband cooling) and allowing cooling to the vibrational ground state. A condition for optimal cooling rates is presented and the cooling behaviour for different Lamb-Dicke parameters and spontaneous decay rates is discussed. Cooling rates of one order of magnitude less than the trapping frequency are achieved using the new cooling method. Furthermore, the scheme exhibits fast rates and low final populations, even for significant deviations from the optimal parameters, and provides good cooling rates also in the multi-particle case.
Laser cooling and control of excitations in superfluid helium
Harris, G I; Sheridan, E; Sachkou, Y; Baker, C; Bowen, W P
2015-01-01
Superfluidity is an emergent quantum phenomenon which arises due to strong interactions between elementary excitations in liquid helium. These excitations have been probed with great success using techniques such as neutron and light scattering. However measurements to-date have been limited, quite generally, to average properties of bulk superfluid or the driven response far out of thermal equilibrium. Here, we use cavity optomechanics to probe the thermodynamics of superfluid excitations in real-time. Furthermore, strong light-matter interactions allow both laser cooling and amplification of the thermal motion. This provides a new tool to understand and control the microscopic behaviour of superfluids, including phonon-phonon interactions, quantised vortices and two-dimensional quantum phenomena such as the Berezinskii-Kosterlitz-Thouless transition. The third sound modes studied here also offer a pathway towards quantum optomechanics with thin superfluid films, including femtogram effective masses, high me...
Direct frequency comb two-photon laser cooling and trapping
Jayich, Andrew; Long, Xueping; Campbell, Wesley C.
2016-05-01
Generating and manipulating high energy photons for spectroscopy on electric dipole transitions of atoms and molecules with deeply bound valence electrons is difficult. Further, laser cooling of such species is even more challenging for lack of laser power. A possible solution is to drive two-photon transitions. This may alleviate the photon energy problem and open the door to cold, trapped samples of highly desirable species with tightly bound electrons. We perform a proof of principle experiment with rubidium by driving a two-photon transition with an optical frequency comb. We perform optical cooling and extend this technique to trapping, where we are able to make a magneto-optical trap in one dimension. This work is supported by the National Science Foundation CAREER program.
Ion microscopy based on laser-cooled cesium atoms.
Viteau, M; Reveillard, M; Kime, L; Rasser, B; Sudraud, P; Bruneau, Y; Khalili, G; Pillet, P; Comparat, D; Guerri, I; Fioretti, A; Ciampini, D; Allegrini, M; Fuso, F
2016-05-01
We demonstrate a prototype of a Focused Ion Beam machine based on the ionization of a laser-cooled cesium beam and adapted for imaging and modifying different surfaces in the few-tens nanometer range. Efficient atomic ionization is obtained by laser promoting ground-state atoms into a target excited Rydberg state, then field-ionizing them in an electric field gradient. The method allows obtaining ion currents up to 130pA. Comparison with the standard direct photo-ionization of the atomic beam shows, in our conditions, a 40-times larger ion yield. Preliminary imaging results at ion energies in the 1-5keV range are obtained with a resolution around 40nm, in the present version of the prototype. Our ion beam is expected to be extremely monochromatic, with an energy spread of the order of the eV, offering great prospects for lithography, imaging and surface analysis.
Rotational Laser Cooling of Vibrationally and Translationally Cold Molecular Ions
DEFF Research Database (Denmark)
Drewsen, Michael
2011-01-01
by sympathetic cooling with Doppler laser cooled Mg+ ions. Giving the time for the molecules to equilibrate internally to the room temperature blackbody radiation, the vibrational degree of freedom will freeze out, leaving only the rotational degree of freedom to be cooled. We report here on the implementation...... of a new technique for laser-induced rotational ground-state cooling of vibrationally and translationally cold MgH+ ions [10]. The scheme is based on excitation of a single rovibrational transition [11], and it should be generalizable to any diatomic polar molecular ion, given appropriate mid......-infrared laser sources such as a quantum cascade laser are available. In recent experiments, a nearly 15-fold increase in the rotational ground-state population was obtained, with the resulting ground-state population of 36,7±1,2 %, equivalent to that of a thermal distribution at about 20 K. The obtained cooling...
Resolved-Sideband Laser Cooling in a Penning Trap.
Goodwin, J F; Stutter, G; Thompson, R C; Segal, D M
2016-04-08
We report the laser cooling of a single ^{40}Ca^{+} ion in a Penning trap to the motional ground state in one dimension. Cooling is performed in the strong binding limit on the 729-nm electric quadrupole S_{1/2}↔D_{5/2} transition, broadened by a quench laser coupling the D_{5/2} and P_{3/2} levels. We find the final ground-state occupation to be 98(1)%. We measure the heating rate of the trap to be very low with n[over ¯][over ˙]≈0.3(2) s^{-1} for trap frequencies from 150-400 kHz, consistent with the large ion-electrode distance.
Rotational laser cooling of vibrationally and translationally cold molecular ions
DEFF Research Database (Denmark)
Staanum, Peter; Højbjerre, Klaus; Skyt, Peter Sandegaard
2010-01-01
-molecular reactions with coherent light fields 8, 9 , for quantum-state-selected bi-molecular reactions 10, 11, 12 and for astrochemistry 12 . Here, we demonstrate rotational ground-state cooling of vibrationally and translationally cold MgH+ ions, using a laser-cooling scheme based on excitation of a single...... rovibrational transition 13, 14 . A nearly 15-fold increase in the rotational ground-state population of the X 1Σ+ electronic ground-state potential has been obtained. The resulting ground-state population of 36.7±1.2% is equivalent to that of a thermal distribution at about 20 K. The obtained cooling results...
Continuous-wave, single-frequency 229 nm laser source for laser cooling of cadmium atoms.
Kaneda, Yushi; Yarborough, J M; Merzlyak, Yevgeny; Yamaguchi, Atsushi; Hayashida, Keitaro; Ohmae, Noriaki; Katori, Hidetoshi
2016-02-15
Continuous-wave output at 229 nm for the application of laser cooling of Cd atoms was generated by the fourth harmonic using two successive second-harmonic generation stages. Employing a single-frequency optically pumped semiconductor laser as a fundamental source, 0.56 W of output at 229 nm was observed with a 10-mm long, Brewster-cut BBO crystal in an external cavity with 1.62 W of 458 nm input. Conversion efficiency from 458 nm to 229 nm was more than 34%. By applying a tapered amplifier (TA) as a fundamental source, we demonstrated magneto-optical trapping of all stable Cd isotopes including isotopes Cd111 and Cd113, which are applicable to optical lattice clocks.
Quantum Computation and Simulation Using Neutral Fermionic Atoms
2014-06-06
State Laser Source for Laser Cooling of Lithium , 39th Annual Meeting of the APS Division of Atomic, Molecular, and Optical Physics. 27-MAY-08...Prof. Lincoln Carr and Laith Haddad from the Colorado School of Mines , we have proposed a method to excite relativistic vortices in a Bose-Einstein...Savard, S. Bali, C. Freed, and J. Thomas, “Ultrastable CO2 laser trapping of lithium fermions,” Phys. Rev. Lett. 82, 4204–4207 (1999). [5] L. Carr
Simulation of Laser Cooling and Trapping in Engineering Applications
Ramirez-Serrano, Jaime; Kohel, James; Thompson, Robert; Yu, Nan; Lunblad, Nathan
2005-01-01
An advanced computer code is undergoing development for numerically simulating laser cooling and trapping of large numbers of atoms. The code is expected to be useful in practical engineering applications and to contribute to understanding of the roles that light, atomic collisions, background pressure, and numbers of particles play in experiments using laser-cooled and -trapped atoms. The code is based on semiclassical theories of the forces exerted on atoms by magnetic and optical fields. Whereas computer codes developed previously for the same purpose account for only a few physical mechanisms, this code incorporates many more physical mechanisms (including atomic collisions, sub-Doppler cooling mechanisms, Stark and Zeeman energy shifts, gravitation, and evanescent-wave phenomena) that affect laser-matter interactions and the cooling of atoms to submillikelvin temperatures. Moreover, whereas the prior codes can simulate the interactions of at most a few atoms with a resonant light field, the number of atoms that can be included in a simulation by the present code is limited only by computer memory. Hence, the present code represents more nearly completely the complex physics involved when using laser-cooled and -trapped atoms in engineering applications. Another advantage that the code incorporates is the possibility to analyze the interaction between cold atoms of different atomic number. Some properties that cold atoms of different atomic species have, like cross sections and the particular excited states they can occupy when interacting with each other and light fields, play important roles not yet completely understood in the new experiments that are under way in laboratories worldwide to form ultracold molecules. Other research efforts use cold atoms as holders of quantum information, and more recent developments in cavity quantum electrodynamics also use ultracold atoms to explore and expand new information-technology ideas. These experiments give a hint
Laser cooling and slowing of CaF molecules
Truppe, Stefan; Williams, Hannah; Hambach, Moritz; Sauer, Ben; Hinds, Ed; Tarbutt, Mike
2016-05-01
We have developed a cold and bright source for CaF molecules and use laser radiation pressure to slow the molecules to within the capture velocity of a magneto-optical trap (MOT). Using laser ablation of Ca into a continuous flow of cryogenic Helium buffer gas mixed with SF6 we produce up to 1011 molecules per steradian per pulse in a single rotational state. The molecules move with a mean forward velocity of 160m/s and have a velocity spread of 80m/s. We then apply laser radiation pressure to the molecular beam to slow and cool the molecules. We form a quasi-closed laser-cooling cycle by using a main cooling laser to drive the B2Σ+ (v' = 0) - X2Σ+ (v'' = 0) transition and a single repump laser to address the A2Π1 / 2 (v' = 0) -X2Σ+ (v'' = 1) transition. Radio-frequency sidebands applied to both lasers address the hyperfine structure. By chirping the frequencies of both lasers to keep the decelerating molecules resonant with the light, we scatter more than 10000 photons and reduce the speed to below 50 m/s. We achieve a similar effect by broadening the linewidth of the laser to several hundred MHz. This ``white-light'' slowing is compared to the chirped slowing technique. We also present progress towards a MOT of CaF molecules.
Sympathetic cooling of molecules with laser-cooled atoms
Hudson, Eric
2014-05-01
Cooling molecules through collisions with laser-cooled atoms is an attractive route to ultracold, ground state molecules. The technique is simple, applicable to a wide class of molecules, and does not require molecule specific laser systems. Particularly suited to this technique are charged molecules, which can be trapped indefinitely, even at room temperature, and undergo strong, short-ranged collisions with ultracold atoms. In this talk, I will focus on recent efforts to use the combination of a magneto-optical trap (MOT) and an ion trap, dubbed the MOTion trap, to produce cold, ground state diatomic charged molecules. The low-energy internal structure of these diatomic molecules, e.g. the electric dipole moment and vibrational, rotational, and Ω-doublet levels, presents a host of opportunities for advances in quantum simulation, precision measurement, cold chemistry, and quantum information. Excitingly, recent proof-of-principle experiments have demonstrated that the MOTion trap is extremely efficient at cooling the vibrational motion of molecular ions. Supported by the ARO and NSF.
Strong-Field Ionization of Laser Cooled Li Atoms
Sharma, Sachin; Romans, Kevin; Fischer, Daniel
2016-05-01
Recently, our understanding of few-body effects has been substantially boosted by the development of intense femto- and attosecond laser sources. Observing the momenta of the fragments of atoms and molecules ionized in these strong fields provided new and before inconceivable insights in molecular and electronic dynamics. Here, we report on a new experiment, where the target atoms (6 Li) are laser cooled and trapped using a magneto optical trap (MOT). Momentum vectors of the target fragments will be measured using a reaction microscope (ReMi). The exclusivity of this setup is a combination of MOT and ReMi, thus dubbed as MOTReMi. Here, the advantages over standard COLTRIMS systems are multifold: Firstly, an unprecedented recoil ion momentum resolution can be achieved, as the target can be prepared at significantly lower temperatures. Second, the atoms can be optically prepared in the ground or in polarized excited states. In a first experimental campaign, studies on single ionization of laser excited and polarized Lithium atoms will be performed with circularly polarized light. This experiment can provide insight into the helicity-dependence of the ionization dynamics as the differences among co- and counter rotating electron and laser field, if any, can be investigated.
Laser cooling and control of excitations in superfluid helium
Harris, G. I.; McAuslan, D. L.; Sheridan, E.; Sachkou, Y.; Baker, C.; Bowen, W. P.
2016-08-01
Superfluidity is a quantum state of matter that exists macroscopically in helium at low temperatures. The elementary excitations in superfluid helium have been probed with great success using techniques such as neutron and light scattering. However, measurements of phonon excitations have so far been limited to average thermodynamic properties or the driven response far out of thermal equilibrium. Here, we use cavity optomechanics to probe the thermodynamics of phonon excitations in real time. Furthermore, strong light-matter interactions allow both laser cooling and amplification. This represents a new tool to observe and control superfluid excitations that may provide insight into phonon-phonon interactions, quantized vortices and two-dimensional phenomena such as the Berezinskii-Kosterlitz-Thouless transition. The third sound modes studied here also offer a pathway towards quantum optomechanics with thin superfluid films, including the prospect of femtogram masses, high mechanical quality factors, strong phonon-phonon and phonon-vortex interactions, and self-assembly into complex geometries with sub-nanometre feature size.
Secondary laser cooling and capturing of thulium atoms in traps
Energy Technology Data Exchange (ETDEWEB)
Sukachev, D D; Kalganova, E S; Sokolov, A V; Fedorov, S A; Vishnyakova, G A; Akimov, A V; Kolachevsky, N N; Sorokin, V N [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)
2014-06-30
Secondary laser cooling has been realised on the weak dipole transition 4f{sup 13}({sup 2}F{sup o})6s{sup 2}, J = 7/2, F=4 → 4f{sup 12}({sup 3}H{sub 6}) 5d{sub 5/2}6s{sup 2}, J' = 9/2, F' = 5 with the wavelength of 530.7 nm and natural width of 350 kHz. The temperature of the atomic cloud in a magnetooptical trap (MOT) was 30 μK at the lifetime of 2 s and the number of atoms 10{sup 5}. Approximately 1% of atoms from the MOT have been reloaded to an optical dipole trap and to one-dimensional optical lattice at the wavelength of 532 nm. The atom lifetime in the optical lattice was 320 ms. We propose to employ thulium atoms captured in an optical lattice as an optical frequency reference. (extreme light fields and their applications)
Laser cooling of organic-inorganic lead halide perovskites
Ha, Son-Tung; Shen, Chao; Zhang, Jun; Xiong, Qihua
2016-02-01
Optical irradiation with suitable energy can cool solids, a phenomenon known as optical refrigeration, first proposed in 1929 and experimentally achieved in ytterbium-doped glasses in 1995. Since then, considerable progress has been made in various rare earth element-doped materials, with a recent record of cooling to 91 K directly from ambient temperatures. For practical use and to suit future applications of optical refrigeration, the discovery of materials with facile and scalable synthesis and high cooling power density will be required. Herein we present the realization of a net cooling of 23.0 K in micrometre-thick 3D CH3NH3PbI3 (MAPbI3) and 58.7 K in exfoliated 2D (C6H5C2H4NH3)2PbI4 (PhEPbI4) perovskite crystals directly from room temperature. We found that the perovskite crystals exhibit strong photoluminescence upconversion and near unity external quantum efficiency, properties that are responsible for the realization of net laser cooling. Our findings indicate that solution-processed perovskite thin films may be a highly suitable candidate for constructing integrated optical cooler devices.
Progress towards the laser cooling of the magnesium fluoride molecular beam
Xia, Yong; Dai, Dapeng; Li, Xingjia; Yin, Yanning; Yin, Jianping
2015-05-01
Though the laser cooling techniques that have been tremendously successful in producing ultracold atoms are difficult to apply to molecules, in the past few years, a new approach, laser cooling and trapping of diatomic molecules has become possible. We select magnesium fluoride (MgF) as a prototype molecule for laser cooling experiment. In order to compensate the changes of the Doppler shift during the longitudinal slowing of the molecular beam, we theoretically investigate the possibility of stimulated light force deceleration and cooling of the diatomic magnesium fluoride molecular beam with near-cycling transitions in the bichromatic standing light wave of high intensity which estimated by the two-level optical Bloch equations. We also demonstrate a robust and versatile solution for locking the continuous-wave Ti:sapphire tunable laser for applications in laser cooling of molecules which need linewidth-narrowed and frequency-stabilized lasers.
Testing Lorentz Invariance with Laser-Cooled Cesium Atomic Frequency Standards
Klipstein, William M.
2004-01-01
This slide presentation reviews the Lorentz invariance testing during the proposed PARCS experiment. It includes information on the primary atomic reference clock in space (PARCS), cesium, laser cooling, and the vision for the future.
Experimental search for the electron electric dipole moment with laser cooled francium atoms
Energy Technology Data Exchange (ETDEWEB)
Inoue, T., E-mail: inoue-t@cyric.tohoku.ac.jp [Tohoku University, Frontier Research Institute of Interdisciplinary Sciences (Japan); Ando, S.; Aoki, T.; Arikawa, H.; Ezure, S.; Harada, K.; Hayamizu, T.; Ishikawa, T.; Itoh, M.; Kato, K.; Kawamura, H.; Uchiyama, A. [Tohoku University, Cyclotron and Radioisotope Center (Japan); Aoki, T. [University of Tokyo, Graduate School of Arts and Sciences (Japan); Asahi, K. [Tokyo Institute of Technology, Department of Physics (Japan); Furukawa, T. [Tokyo Metropolitan University, Department of Physics (Japan); Hatakeyama, A. [Tokyo University of Agriculture and Technology, Department of Applied Physics (Japan); Hatanaka, K. [Osaka University, Research Center for Nuclear Physics (Japan); Imai, K. [Advanced Science Research Center, Japan Atomic Energy Agency (Japan); Murakami, T. [Kyoto University, Department of Physics (Japan); Nataraj, H. S. [Indian Institute of Technology Roorkee (India); and others
2015-04-15
A laser cooled heavy atom is one of the candidates to search for the permanent electric dipole moment (EDM) of the electron due to the enhancement mechanism and its long coherence time. The laser cooled francium (Fr) factory has been constructed to perform the electron EDM search at the Cyclotron and Radioisotope Center, Tohoku University. The present status of Fr production and the EDM measurement system is presented.
Energy Technology Data Exchange (ETDEWEB)
Mickelson, P G; De Escobar, Y N Martinez; Anzel, P; DeSalvo, B J; Nagel, S B; Traverso, A J; Yan, M; Killian, T C, E-mail: killian@rice.ed [Department of Physics and Astronomy, Rice University, Houston, TX 77251 (United States)
2009-12-14
We describe repumping and spectroscopy of laser-cooled strontium (Sr) atoms using the (5s5p){sup 3}P{sub 2}-(5s4d){sup 3}D{sub 2} transition. Atom number in a magneto-optical trap is enhanced by driving this transition because Sr atoms that have decayed into the (5s5p){sup 3}P{sub 2} dark state are repumped back into the (5s{sup 2}){sup 1}S{sub 0} ground state. Spectroscopy of {sup 84}Sr, {sup 86}Sr, {sup 87}Sr and {sup 88}Sr improves the value of the (5s5p){sup 3}P{sub 2}-(5s4d){sup 3}D{sub 2} transition frequency and determines the isotope shifts for the transition accurately enough to guide laser-cooling experiments with less abundant isotopes.
Vibrational branching ratios and hyperfine structure of BH and its suitability for laser cooling
Hendricks, Richard; Holland, Darren; Truppe, Stefan; Sauer, Ben; Tarbutt, Michael
2014-08-01
The simple structure of the BH molecule makes it an excellent candidate for direct laser cooling. We measure the branching ratios for the decay of the A^{1}Pi (v'=0) state to vibrational levels of the ground state, X^{1}Sigma^{+}, and find that they are exceedingly favourable for laser cooling. We verify that the branching ratio for the spin-forbidden transition to the intermediate a^{3}Pi state is inconsequentially small. We measure the frequency of the lowest rotational transition of the X state, and the hyperfine structure in the relevant levels of both the X and A states, and determine the nuclear electric quadrupole and magnetic dipole coupling constants. Our results show that, with a relatively simple laser cooling scheme, a Zeeman slower and magneto-optical trap can be used to cool, slow and trap BH molecules.
Hendricks, R J; Truppe, S; Sauer, B E; Tarbutt, M R
2014-01-01
The simple structure of the BH molecule makes it an excellent candidate for direct laser cooling. We measure the branching ratios for the decay of the ${\\rm A}^{1}\\Pi (v'=0)$ state to vibrational levels of the ground state, ${\\rm X}^{1}\\Sigma^{+}$, and find that they are exceedingly favourable for laser cooling. We verify that the branching ratio for the spin-forbidden transition to the intermediate ${\\rm a}^{3}\\Pi$ state is inconsequentially small. We measure the frequency of the lowest rotational transition of the X state, and the hyperfine structure in the relevant levels of both the X and A states, and determine the nuclear electric quadrupole and magnetic dipole coupling constants. Our results show that, with a relatively simple laser cooling scheme, a Zeeman slower and magneto-optical trap can be used to cool, slow and trap BH molecules.
Cavity-enhanced laser cooling of solid-state materials in a standing-wave cavity
Institute of Scientific and Technical Information of China (English)
Youhua Jia; Biao Zhong; Jianping Yin
2008-01-01
We propose a new method to cool the Yba+-doped ZBLANP glass in a standing-wave cavity. There are two advantages of this cavity-enhanced technique: the pumping power is greatly enhanced and the absorption of the cooling material is greatly increased. We introduce the basic principle of the cavity-enhanced laser cooling and discuss the cooling effect of a solid-state material in a cavity. From the theoretical study, it is found that the laser cooling effect is strongly dependent on the reflectivity of the cavity mirrors, the length of the solid material, the surface scattering of the material, and so on. Some optimal parameters for efficient laser cooling are obtained.
Super-radiance and fluorescence are two approaches to laser cooling of solids
Nemova, Galina; Kashyap, Raman
2011-08-01
A new approach to cool solids with super-radiance (SR) pulses is presented in comparison with laser cooling based on traditional anti-Stokes fluorescence. Contrary to the anti-Stokes fluorescence, which is in-coherent radiation propagating in all directions around a sample, SR is the coherent, sharply directed spontaneous emission of photons by a system of excited ions. We consider an Yb3+ doped ZBLAN sample pumped at the wavelength 1015nm with a rectangular pulsed source. The intensity of the SR is proportional to the square of the number of excited ions. This unique feature of SR permits an increase in the rate of the cooling process in comparison with the traditional laser cooling of the rare earth doped solids with anti-Stokes fluorescence. This scheme overcomes the limitation of using only low phonon energy glasses for laser cooling.
Vibrational branching ratios and hyperfine structure of BH and its suitability for laser cooling
Directory of Open Access Journals (Sweden)
Richard eHendricks
2014-08-01
Full Text Available The simple structure of the BH molecule makes it an excellent candidate for direct laser cooling. We measure the branching ratios for the decay of the A^{1}Pi (v'=0 state to vibrational levels of the ground state, X^{1}Sigma^{+}, and find that they are exceedingly favourable for laser cooling. We verify that the branching ratio for the spin-forbidden transition to the intermediate a^{3}Pi state is inconsequentially small. We measure the frequency of the lowest rotational transition of the X state, and the hyperfine structure in the relevant levels of both the X and A states, and determine the nuclear electric quadrupole and magnetic dipole coupling constants. Our results show that, with a relatively simple laser cooling scheme, a Zeeman slower and magneto-optical trap can be used to cool, slow and trap BH molecules.
Metastable D-state spectroscopy and laser cooling of barium
Dammalapati, Umakanth
2006-01-01
This thesis is written as a part of the TRImP programme. Rare and short-lived radioactive isotopes offer new possibilities for investigating fundamental interactions and symmetries. Radium, a radioactive alkaline earth element has been identified as a new candidate for searches for a permanent
Metastable D-state spectroscopy and laser cooling of barium
Dammalapati, Umakanth
2006-01-01
This thesis is written as a part of the TRImP programme. Rare and short-lived radioactive isotopes offer new possibilities for investigating fundamental interactions and symmetries. Radium, a radioactive alkaline earth element has been identified as a new candidate for searches for a permanent elect
Vertical blow-up in a low-current, stored, laser-cooled ion beam
Madsen, N; Siegfried, L E; Hangst, J S; Nielsen, J
2003-01-01
Using a novel technique for real-time transverse beam profile diagnostics of a stored ion beam, we have observed the transverse size of a stored, laser-cooled ion beam. Earlier we observed that the density of the beam is independent of the beam current. At very low currents we observe an abrupt change in this behavior: the vertical beam size increases suddenly by about an order of magnitude. This observation implies a sudden change in the indirect vertical cooling mediated by intrabeam scattering. Our results have serious implications for the ultimate beam quality attainable by laser- cooling. (12 refs).
Note: A four-pass acousto-optic modulator system for laser cooling of sodium atoms
Lu, Bo; Wang, Dajun
2017-07-01
We present a four-pass acousto-optic modulator (AOM) system for providing the repumping light for laser cooling of sodium atoms. With only one 400 MHz AOM, we achieve a tunable laser frequency shift around 1.6 GHz with total efficiency up to 30%. This setup provides an alternative over conventional methods to generate a sodium repumping light using more expensive high frequency AOMs or electro-optical modulators (EOMs) in the GHz domain. This compact and reliable setup can be easily adapted to other frequencies and may find applications in laser spectroscopy, laser cooling and trapping, and coherent manipulation of atomic quantum states.
Energy Technology Data Exchange (ETDEWEB)
Chimento, L P; Forte, M [Physics Department, UBA, 1428 Buenos Aires (Argentina); Devecchi, F P; Kremer, G M; Ribas, M O; Samojeden, L L, E-mail: kremer@fisica.ufpr.br, E-mail: devecchi@fisica.ufpr.br, E-mail: chimento@df.uba.ar [Physics Department, UFPR, 81531-990 Curitiba (Brazil)
2011-07-08
In this work we review if fermionic sources could be responsible for accelerated periods during the evolution of a FRW universe. In a first attempt, besides the fermionic source, a matter constituent would answer for the decelerated periods. The coupled differential equations that emerge from the field equations are integrated numerically. The self-interaction potential of the fermionic field is considered as a function of the scalar and pseudo-scalar invariants. It is shown that the fermionic field could behave like an inflaton field in the early universe, giving place to a transition to a matter dominated (decelerated) period. In a second formulation we turn our attention to analytical results, specifically using the idea of form-invariance transformations. These transformations can be used for obtaining accelerated cosmologies starting with conventional cosmological models. Here we reconsider the scalar field case and extend the discussion to fermionic fields. Finally we investigate the role of a Dirac field in a Brans-Dicke (BD) context. The results show that this source, in combination with the BD scalar, promote a final eternal accelerated era, after a matter dominated period.
Laser cooled ion beams and strongly coupled plasmas for precision experiments
Energy Technology Data Exchange (ETDEWEB)
Bussmann, Michael
2008-03-17
This cumulative thesis summarizes experimental and theoretical results on cooling of ion beams using single-frequency, single-mode tabletop laser systems. It consists of two parts. One deals with experiments on laser-cooling of ion beams at relativistic energies, the other with simulations of stopping and sympathetic cooling of ions for precision in-trap experiments. In the first part, experimental results are presented on laser-cooling of relativistic C{sup 3+} ion beams at a beam energy of 122 MeV/u, performed at the Experimental Storage Ring (ESR) at GSI. The main results presented in this thesis include the first attainment of longitudinally space-charge dominated relativistic ion beams using pure laser-cooling. The second part lists theoretical results on stopping and sympathetic cooling of ions in a laser-cooled one-component plasma of singly charged {sup 24}Mg ions, which are confined in a three-dimensional harmonic trap potential. (orig.)
Creation of an Ultracold Plasma by Photoionizing Laser-Cooled Cesium Atom
Institute of Scientific and Technical Information of China (English)
JING Qun; FENG Zhi-Gang; ZHANG Lin-Jie; LI Chang-Yong; ZHAO Jian-Ming; JIA Suo-Tang
2008-01-01
@@ The signals of ultracold plasma are observed by two-photon ionization of laser-cooled atom in a caesium magneto-optical trap.A simple model has been introduced to explain the creation of plasma, and the mechanism is further investigated by changing the energy of a pulsed dye laser and the number of initial cooled atoms.
Brown, R C; Wu, S; Dyckovsky, A M; Wyllie, R; Porto, J V
2014-01-01
We present two complementary designs of pneumatically actuated and kinematically positioned optics mounts: one designed for vertical mounting and translation, the other designed for horizontal mounting and translation. The design and measured stability make these mounts well-suited to experiments with laser-cooled atoms.
Frontiers in Laser Cooling, Single-Molecule Biophysics, and Enrgy Science: A Talk by Carl Wieman
Energy Technology Data Exchange (ETDEWEB)
Wieman, Carl
2008-08-30
Carl Wieman presents a talk at Frontiers in Laser Cooling, Single-Molecule Biophysics and Energy Science, a scientific symposium honoring Steve Chu, director of Lawrence Berkeley National Laboratory and recipient of the 1997 Nobel Prize in Physics. The symposium was held August 30, 2008 in Berkeley.
A Single Laser Cooled Trapped 40Ca+ Ion in a Miniature Paul Trap
Institute of Scientific and Technical Information of China (English)
SHU Hua-Lin; GUAN Hua; HUANG Xue-Ren; LI Jiao-Mei; GAO Ke-Lin
2005-01-01
@@ We have observed the phenomenon of phase transition of a few trapped ions in a miniature Paul trap. Judging from the quantum jump signals, a single laser-cooled trapped Ca+ ion has been realized. The ion temperature is estimated to be 22mK. The result shows that the amplitude of ion micromotion is strongly dependent on the rf voltage.
Laser cooling and optical detection of excitations in a LC electrical circuit
DEFF Research Database (Denmark)
Taylor, J. M.; Sørensen, Anders Søndberg; Marcus, Charles Masamed
2011-01-01
We explore a method for laser cooling and optical detection of excitations in a room temperature LC electrical circuit. Our approach uses a nanomechanical oscillator as a transducer between optical and electronic excitations. An experimentally feasible system with the oscillator capacitively...
A Technology Demonstration Experiment for Laser Cooled Atomic Clocks in Space
Klipstein, W. M.; Kohel, J.; Seidel, D. J.; Thompson, R. J.; Maleki, L.; Gibble, K.
2000-01-01
We have been developing a laser-cooling apparatus for flight on the International Space Station (ISS), with the intention of demonstrating linewidths on the cesium clock transition narrower than can be realized on the ground. GLACE (the Glovebox Laser- cooled Atomic Clock Experiment) is scheduled for launch on Utilization Flight 3 (UF3) in 2002, and will be mounted in one of the ISS Glovebox platforms for an anticipated 2-3 week run. Separate flight definition projects funded at NIST and Yale by the Micro- gravity Research Division of NASA as a part of its Laser Cooling and Atomic Physics (LCAP) program will follow GLACE. Core technologies for these and other LCAP missions are being developed at JPL, with the current emphasis on developing components such as the laser and optics subsystem, and non-magnetic vacuum-compatible mechanical shutters. Significant technical challenges in developing a space qualifiable laser cooling apparatus include reducing the volume, mass, and power requirements, while increasing the ruggedness and reliability in order to both withstand typical launch conditions and achieve several months of unattended operation. This work was performed at the Jet Propulsion Laboratory under a contract with the National Aeronautics and Space Administration.
Laser cooling of the OH(-) molecular anion in a theoretical investigation.
Wan, Ming-Jie; Huang, Duo-Hui; Yu, You; Zhang, Yun-Guang
2017-10-03
The schemes for laser cooling of the OH(-) anion are proposed using an ab initio method. Scalar relativistic corrections are considered using the Douglas-Kroll Hamilton. Spin-orbit coupling (SOC) effects are taken into account at the MRCI+Q level. SOC effects play important roles in the transition properties of the OH(-) anion. Transition strengths for the transition of the OH(-) anion cannot be ignored. Large vibrational branching ratios for the and transitions are determined. Short spontaneous radiative lifetimes for the a(3)Π1 and A(1)Π1 states are also predicted for rapid laser cooling. The vibrational branching loss ratio to the intervening states a(3)Π0 and a(3)Π1 for the transition is small enough to enable the building of a laser cooling project. The three required laser wavelengths for the and transitions are all in the visible region. The results imply the probability of laser cooling of the OH(-) anion via both a spin-forbidden transition and a three-electronic-level transition.
Efficient sub-Doppler transverse laser cooling of an indium atomic beam
Energy Technology Data Exchange (ETDEWEB)
Kim, Jae-Ihn
2009-07-23
Laser cooled atomic gases and atomic beams are widely studied samples in experimental research in atomic and optical physics. For the application of ultra cold gases as model systems for e.g. quantum many particle systems, the atomic species is not very important. Thus this field is dominated by alkaline, earthalkaline elements which are easily accessible with conventional laser sources and have convenient closed cooling transition. On the other hand, laser cooled atoms may also be interesting for technological applications, for instance for the creation of novel materials by atomic nanofabrication (ANF). There it will be important to use technologically relevant materials. As an example, using group III atoms of the periodical table in ANF may open a route to generate fully 3D structured composite materials. The minimal requirement in such an ANF experiment is the collimation of an atomic beam which is accessible by one dimensional laser cooling. In this dissertation, I describe transverse laser cooling of an Indium atomic beam. For efficient laser cooling on a cycling transition, I have built a tunable, continuous-wave coherent ultraviolet source at 326 nm based on frequency tripling. For this purpose, two independent high power Yb-doped fiber amplifiers for the generation of the fundamental radiation at {lambda}{sub {omega}} = 977 nm have been constructed. I have observed sub-Doppler transverse laser cooling of an Indium atomic beam on a cycling transition of In by introducing a polarization gradient in the linear-perpendicular-linear configuration. The transverse velocity spread of a laser-cooled In atomic beam at full width at half maximum was achieved to be 13.5{+-}3.8 cm/s yielding a full divergence of only 0.48 {+-} 0.13 mrad. In addition, nonlinear spectroscopy of a 3-level, {lambda}-type level system driven by a pump and a probe beam has been investigated in order to understand the absorption line shapes used as a frequency reference in a previous two
Fry, M. P.
2001-01-01
The current status of bounds on and limits of fermion determinants in two, three and four dimensions in QED and QCD is reviewed. A new lower bound on the two-dimensional QED determinant is derived. An outline of the demonstration of the continuity of this determinant at zero mass when the background magnetic field flux is zero is also given.
Energy Technology Data Exchange (ETDEWEB)
Giri, G.S.; Boell, O.; Jungmann, K.; Sahoo, B.K.; Timmermans, R.G.E.; Versolato, O.O.; Wansbeek, L.W.; Willmann, L. [KVI, University of Groningen (Netherlands)
2009-07-01
One single-trapped and laser cooled radium ion is an ideal candidate to investigate atomic parity non-conservation (APNC). APNC can serve as a low energy test of the Standard Model of particle physics. We aim for a precision measurement of the electroweak mixing angle, by probing the differential light shift of the 7S and 6D Zeeman sublevels. This shift is caused by the interaction of the ion with an off-resonant laser light field. With precision RF spectroscopy and subsequent electron shelving, the differential splitting can be determined to sub-Hertz accuracy. Recent calculations show that Ra{sup +} is a superior candidate for probing APNC. With an almost identical set-up and using the electron shelving technique, ultra-narrow transitions in this ion can be exploited for an all optical, high stability frequency standard clock. We have succeeded in the production and subsequent slowing down of radium isotopes around {sup 213}Ra. Further progress has been made in the development of ion traps and the necessary high precision optical laboratory. Laser spectroscopy of Ra{sup +} and the first ever trapping of this particle are being prepared.
Wang, Zhijun; Alexandradinata, A.; Cava, Robert J.; Bernevig, B. Andrei
Spatial symmetries in crystals are distinguished by whether they preserve the spatial origin. We show how this basic geometric property gives rise to a new topology in band insulators. We study spatial symmetries that translate the origin by a fraction of the lattice period, and find that these nonsymmorphic symmetries protect a novel surface fermion whose dispersion is shaped like an hourglass; surface bands connect one hourglass to the next in an unbreakable zigzag pattern. These exotic fermions are materialized in the large-gap insulators: KHg X (X = As,Sb,Bi), which we propose as the first material class whose topology relies on nonsymmorphic symmetries. Beside the hourglass fermion, a different surface of KHg X manifests a 3D generalization of the quantum spin Hall effect. To describe the bulk topology of nonsymmorphic crystals, we propose a non-Abelian generalization of the geometric theory of polarization. Our nontrivial topology originates not from an inversion of the parity quantum numbers, but rather of the rotational quantum numbers, which we propose as a fruitful in the search for topological materials. Finally, KHg X uniquely exemplifies a cohomological insulator, a concept that we will introduce in a companion work.
Microwave sidebands for laser cooling by direct modulation of a tapered amplifier
Mahnke, J.; Kulas, S.; Geisel, I.; Jöllenbeck, S.; Ertmer, W.; Klempt, C.
2013-06-01
Laser cooling of atoms usually necessitates several laser frequencies. Alkaline atoms, for example, are cooled by two lasers with a frequency difference in the gigahertz range. This gap cannot be closed with simple shifting techniques. Here, we present a method of generating sidebands at 6.6 GHz by modulating the current of a tapered amplifier, which is seeded by an unmodulated master laser. The sidebands enable trapping of 1.1 × 109 87Rb atoms in a chip-based magneto-optical trap. Compared to the direct modulation of the master laser, this method allows for an easy implementation, a fast adjustment over a wide frequency range, and the simultaneous extraction of unmodulated light for manipulation and detection. The low power consumption, small size, and applicability for multiple frequencies benefit a wide range of applications reaching from atom-based mobile sensors to the laser cooling of molecules.
Microwave sidebands for laser cooling by direct modulation of a tapered amplifier
Mahnke, Jan; Geisel, Ilka; Jöllenbeck, Stefan; Ertmer, Wolfgang; Klempt, Carsten
2013-01-01
Laser cooling of atoms usually necessitates several laser frequencies. Alkaline atoms, for example, are cooled by two lasers with a frequency difference in the Gigahertz range. This gap cannot be closed with simple shifting techniques. Here, we present a method of generating sidebands at 6.6 GHz by modulating the current of a tapered amplifier which is seeded by an unmodulated master laser. The sidebands enable trapping of 1.1*10^9 Rubidium 87 atoms in a chip-based magneto-optical trap. Compared to the direct modulation of the master laser, this method allows for an easy implementation, a fast adjustment over a wide frequency range and the simultaneous extraction of unmodulated light for manipulation and detection. The low power consumption, small size and applicability for multiple frequencies benefits a wide range of applications, reaching from atom-based mobile sensors to the laser cooling of molecules.
Developing Density of Laser-Cooled Neutral Atoms and Molecules in a Linear Magnetic Trap
Velasquez, Joe, III; Walstrom, Peter; di Rosa, Michael
2013-05-01
In this poster we show that neutral particle injection and accumulation using laser-induced spin flips may be used to form dense ensembles of ultracold magnetic particles, i.e., laser-cooled paramagnetic atoms and molecules. Particles are injected in a field-seeking state, are switched by optical pumping to a field-repelled state, and are stored in the minimum-B trap. The analogous process in high-energy charged-particle accumulator rings is charge-exchange injection using stripper foils. The trap is a linear array of sextupoles capped by solenoids. Particle-tracking calculations and design of our linear accumulator along with related experiments involving 7Li will be presented. We test these concepts first with atoms in preparation for later work with selected molecules. Finally, we present our preliminary results with CaH, our candidate molecule for laser cooling. This project is funded by the LDRD program of Los Alamos National Laboratory.
Breaking the low phonon energy barrier for laser cooling in rare-earth doped hosts
Nemova, Galina; Kashyap, Raman
2011-03-01
A new approach to cool rare earth doped solids with optical super-radiance (SR) is presented. SR is the coherent, sharply directed spontaneous emission of photons by a system excited with a pulsed laser. We consider an Yb3+ doped ZBLAN sample pumped at the wavelength 1015nm with a rectangular pulsed source with a power of ~700W and duration of 20ns. The intensity of the SR is proportional to the square of the number of excited ions. This unique feature of SR permits an increase in the rate of the cooling process in comparison with the traditional laser cooling of the rare earth doped solids with anti-Stokes spontaneous incoherent radiation (fluorescence). This scheme overcomes the limitation of using only low phonon energy glasses for laser cooling.
Minimization of temperature for laser cooling of Yb-ion-doped crystals.
Ivanov, Andrei; Rozhdestvensky, Yuriy; Perlin, Evgeniy
2016-10-01
In this paper, quantum mechanical calculations of cooling characteristics for the Yb3+: YLF system with use of the vibronic model of laser cooling are presented. Dynamics of the laser cooling process for the seven-level system of an Yb ion is described by the density-matrix formalism. Dependences of the cooling characteristics on the pump intensity are obtained for various temperatures and absorption coefficients of impurity ions. It is shown that the pump intensity, at which the net cooling power has a maximum, depends on temperature. Thus, choosing the intensities, which correspond to the net cooling power maximum over the entire temperature range, we achieve a lower sample temperature at a shorter time than in the case of using a constant intensity throughout the cooling process. Calculations are performed for the parameters of the Yb3+:YLF system.
Fordell, Thomas; Wallin, Anders E; Lindvall, Thomas; Vainio, Markku; Merimaa, Mikko
2014-11-01
Laser cooling of trapped atoms and ions in optical clocks demands stable light sources with precisely known absolute frequencies. Since a frequency comb is a vital part of any optical clock, the comb lines can be used for stabilizing tunable, user-friendly diode lasers. Here, a light source for laser cooling of trapped strontium ions is described. The megahertz-level stability and absolute frequency required are realized by stabilizing a distributed-feedback semiconductor laser to a frequency comb. Simple electronics is used to lock and scan the laser across the comb lines, and comb mode number ambiguities are resolved by using a separate, saturated absorption cell that exhibits easily distinguishable hyperfine absorption lines with known frequencies. Due to the simplicity, speed, and wide tuning range it offers, the employed technique could find wider use in precision spectroscopy.
Injection locking of a high power ultraviolet laser diode for laser cooling of ytterbium atoms.
Hosoya, Toshiyuki; Miranda, Martin; Inoue, Ryotaro; Kozuma, Mikio
2015-07-01
We developed a high-power laser system at a wavelength of 399 nm for laser cooling of ytterbium atoms with ultraviolet laser diodes. The system is composed of an external cavity laser diode providing frequency stabilized output at a power of 40 mW and another laser diode for amplifying the laser power up to 220 mW by injection locking. The systematic method for optimization of our injection locking can also be applied to high power light sources at any other wavelengths. Our system does not depend on complex nonlinear frequency-doubling and can be made compact, which will be useful for providing light sources for laser cooling experiments including transportable optical lattice clocks.
Microwave sidebands for laser cooling by direct modulation of a tapered amplifier.
Mahnke, J; Kulas, S; Geisel, I; Jöllenbeck, S; Ertmer, W; Klempt, C
2013-06-01
Laser cooling of atoms usually necessitates several laser frequencies. Alkaline atoms, for example, are cooled by two lasers with a frequency difference in the gigahertz range. This gap cannot be closed with simple shifting techniques. Here, we present a method of generating sidebands at 6.6 GHz by modulating the current of a tapered amplifier, which is seeded by an unmodulated master laser. The sidebands enable trapping of 1.1 × 10(9) (87)Rb atoms in a chip-based magneto-optical trap. Compared to the direct modulation of the master laser, this method allows for an easy implementation, a fast adjustment over a wide frequency range, and the simultaneous extraction of unmodulated light for manipulation and detection. The low power consumption, small size, and applicability for multiple frequencies benefit a wide range of applications reaching from atom-based mobile sensors to the laser cooling of molecules.
Rotational Laser Cooling of MgH+ Ions and Rotational Rate Measurements
DEFF Research Database (Denmark)
Hansen, Anders Kragh; Staanum, Peter; Højbjerre, Klaus
A method of laser cooling vibrationally and translationally cold trapped MgH+ ions to the rotational ground state using optical pumping was recently demonstrated in our group [1]. This method relies on the 293 K blackbody radiation to redistribute population among the rotational states, while...... chemists making electronic structure calculations, since the electric dipole moments that can be extracted from the results will provide information not present in pectroscopic data. [1] P. F. Staanum, K. Højbjerre, P. S. Skyt, A. K. Hansen, and M. Drewsen. Rotational laser cooling of vibrationally...... exciting a single rovibrational transition within the X1Σ+ electronic ground state for optical pumping into the rovibrational ground state. To model the expected rotational state distributions after the application of the laser beam, one has to know the various rotational transitions rates in the present...
Laser cooling of beryllium ions using a frequency-doubled 626 nm diode laser.
Cozijn, F M J; Biesheuvel, J; Flores, A S; Ubachs, W; Blume, G; Wicht, A; Paschke, K; Erbert, G; Koelemeij, J C J
2013-07-01
We demonstrate laser cooling of trapped beryllium ions at 313 nm using a frequency-doubled extended cavity diode laser operated at 626 nm, obtained by cooling a ridge waveguide diode laser chip to -31°C. Up to 32 mW of narrowband 626 nm laser radiation is obtained. After passage through an optical isolator and beam shaping optics, 14 mW of 626 nm power remains of which 70% is coupled into an external enhancement cavity containing a nonlinear crystal for second-harmonic generation. We produce up to 35 μW of 313 nm radiation, which is subsequently used to laser cool and detect 6×10(2) beryllium ions, stored in a linear Paul trap, to a temperature of about 10 mK, as evidenced by the formation of Coulomb crystals. Our setup offers a simple and affordable alternative for Doppler cooling, optical pumping, and detection to presently used laser systems.
Structures, Branching Ratios and Laser Cooling Scheme for 138BaF Molecule
Chen, Tao; Yan, Bo
2016-01-01
For laser cooling considerations, we have theoretically investigated the electronic, rovibrational and hypefine structures of BaF molecule. The highly diagonal Franck-Condon factors and the branching ratios for all possible transitions within the lowest-lying four electronic states have also been calculated. Meanwhile, the mixing between metastable A'2{\\Delta} and A2{\\Pi} states and further the lifetime of the {\\Delta} state have been estimated since the loss procedure via {\\Delta} state would like fatally destroy the main quasi-cycling {\\Sigma}-{\\Pi} transition for cooling and trapping. The resultant hyperfine splittings of each rovibrational states in X2{\\Sigma}+ state provide benchmarksfor sideband modulations of cooling and repumping lasers and remixing microwaves to address all necessary levels. The calculated Zeeman shift and g-factors for both X and A states serve as benchmarks for selections of the trapping laser polarizations. Our study paves the way for future laser cooling and magneto-optical trapp...
Frequency Measurement of the Electric Quadrupole Transition in a Single Laser-Cooled 40Ca+
Institute of Scientific and Technical Information of China (English)
LIU Qu; HUANG Yao; CAO Jian; OU Bao-Quan; GUO Bin; GUAN Hua; HUANG Xue-Ren; GAO Ke-Lin
2011-01-01
The optical frequency of the 4s2S1/2-3d2D5/2 transition in a single trapped and laser-cooled 40Ca+ ion is measured with an optical frequency comb system referenced to a hydrogen maser. A 729-nm laser can be locked to the clock transition about ten hours and the Allan deviation is better than 2 × 10-14/1000s.
Laser cooling of BeCl and BeBr molecules in an ab initio method.
Wan, Ming-jie; Shao, Ju-xiang; Huang, Duo-hui; Jin, Cheng-guo; Yu, You; Wang, Fan-hou
2015-10-28
In this study, the feasibility of laser-cooling of BeCl and BeBr molecules is studied using ab initio quantum chemistry. The potential energy curves for the X(2)Σ(+), A(2)Π, and 2(2)Π electronic states of BeCl and BeBr are plotted based on multi-reference configuration interaction plus Davidson corrections (MRCI + Q), and the spin-orbit coupling (SOC) effects are considered at the MRCI + Q level. The calculated spectroscopic parameters agree with the experimental data. Highly diagonally distributed Franck-Condon factors are determined for the A(2)Π(ν' = 0) ← X(2)Σ(+)(ν'' = 0) transition: f00(BeCl) = 0.947 and f00(BeBr) = 0.966. Moreover, the suitable radiative lifetimes τ of the A(2)Π(ν' = 0) state are determined for rapid laser cooling: τ(BeCl) = 18.38 ns and τ(BeBr) = 27.09 ns. The proposed cooling wavelengths of both BeCl and BeBr are within the ultraviolet region at λ00(BeCl) = 358.51 nm and λ00(BeBr) = 379.38 nm. Laser cooling schemes for BeCl and BeBr molecules are also developed in consideration of the SOC effects. These results indicate that the inclusion of SOC effects does not affect the judgment of the feasibility of laser cooling of BeCl and BeBr molecules, even for the given BeBr molecules in which the SOC effect is significant.
Laser cooling of BH and GaF: insights from an ab initio study.
Gao, Yu-feng; Gao, Tao
2015-04-28
The feasibility of laser cooling BH and GaF is investigated using ab initio quantum chemistry. The ground state X (1)Σ(+) and first two excited states (3)Π and (1)Π of BH and GaF are calculated using the multireference configuration interaction (MRCI) level of theory. For GaF, the spin-orbit coupling effect is also taken into account in the electronic structure calculations at the MRCI level. Calculated spectroscopic constants for BH and GaF show good agreement with available theoretical and experimental results. The highly diagonal Franck-Condon factors (BH: f00 = 0.9992, f11 = 0.9908, f22 = 0.9235; GaF: f00 = 0.997, f11 = 0.989, f22 = 0.958) for the (1)Π (v' = 0-2) → X (1)Σ(+) (v = 0-2) transitions in BH and GaF are determined, which are found to be in good agreement with the theoretical and experimental data. Radiative lifetime calculations of the (1)Π (v' = 0-2) state (BH: 131, 151, and 187 ns; GaF: 2.26, 2.36, and 2.48 ns) are found to be short enough for rapid laser cooling. The proposed laser cooling schemes that drive the (1)Π (v' = 0) → X (1)Σ(+) (v = 0) transition use just one laser wavelength λ00 (BH: 436 nm, GaF: 209 nm). Though the cooling wavelength of GaF is deep in the UVC, a frequency quadrupled Ti:sapphire laser (189-235 nm) could be capable of generating useful quantities of light at this wavelength. The present results indicate that BH and GaF are two good choices of molecules for laser cooling.
Trapping, retention and laser cooling of Th3+ ions in a multisection linear quadrupole trap
Borisyuk, P. V.; Vasil'ev, O. S.; Derevyashkin, S. P.; Kolachevsky, N. N.; Lebedinskii, Yu. Yu.; Poteshin, S. S.; Sysoev, A. A.; Tkalya, E. V.; Tregubov, D. O.; Troyan, V. I.; Khabarova, K. Yu.; Yudin, V. I.; Yakovlev, V. P.
2017-06-01
A multisection linear quadrupole trap for Th3+ ions is described. Multiply charged ions are obtained by the laser ablation method. The possibility of trapping and retention of ˜103 ions is demonstrated in macroscopic time scales of ˜30 s. Specific features of cooling Th3+ ions on the electron transitions with wavelengths of 1088, 690 and 984 nm in Th3+ ion are discussed; a principal scheme of a setup for laser cooling is presented.
Clock Technology Development in the Laser Cooling and Atomic Physics (LCAP) Program
Seidel, Dave; Thompson, R. J.; Klipstein, W. M.; Kohel, J.; Maleki, L.
2000-01-01
This paper presents the Laser Cooling and Atomic Physics (LCAP) program. It focuses on clock technology development. The topics include: 1) Overview of LCAP Flight Projects; 2) Space Clock 101; 3) Physics with Clocks in microgravity; 4) Space Clock Challenges; 5) LCAP Timeline; 6) International Space Station (ISS) Science Platforms; 7) ISS Express Rack; 8) Space Qualification of Components; 9) Laser Configuration; 10) Clock Rate Comparisons: GPS Carrier Phase Frequency Transfer; and 11) ISS Model Views. This paper is presented in viewgraph form.
Vibrational branching ratios and radiative lifetimes in the laser cooling of AlBr.
Gao, Yufeng; Wan, Mingjie
2017-02-15
The feasibility of laser cooling of the AlBr molecule is investigated using ab initio quantum chemistry. Potential energy curves, permanent dipole moments, and transition dipole moments for the ground state X(1)Σ(+) and the first two excited states (a(3)Π and A(1)Π) are calculated using the multi-reference configuration interaction plus Davidson corrections (MRCI+Q) method with the ACVQZ basis set; the spin-orbit coupling effects are also taken into account in electronic structure calculations at the MRCI level. Based on the acquired potential energy curves and transition dipole moments, highly diagonally distributed Franck-Condon factors (f00 = 0.9540, f11 = 0.8172) and vibrational branching ratios (R00 = 0.9708, R11 = 0.8420) for the transition are determined. Radiative lifetime calculations of the A(1)Π1 (ν' = 0-4) state are found to be short (9.16-11.48 ns) enough for rapid laser cooling. The proposed main cycling laser drives the transition at the wavelength λ00 = 279.19 nm. The vibrational branching loss ratios of the A(1)Π1 (ν') state to the intervening states a(3)Π0(+) and a(3)Π1 are small (laser cooling.
The ab initio study of laser cooling of BBr and BCl.
Yang, Rong; Gao, Yufeng; Tang, Bin; Gao, Tao
2015-01-21
We investigate the feasibility of laser cooling BBr and BCl using ab initio quantum chemistry. The multi-reference configuration interaction method (MRCI) is used to calculate the ground state X(1)Σ(+) and the low-lying excited state A(1)Π, where Davidson modification with the Douglas-Kroll scalar relativistic correction is also taken into account. The calculated spectroscopic constants are in good agreement with available experimental values. The potential energy curves, permanent dipole moments (PDMs), transition dipole moments (TDMs) followed by Franck-Condon factors and radiative times for the transitions from the A(1)Π state to the ground state X(1)Σ(+) are obtained as well. The determined Franck-Condon factors are highly diagonally distributed and the evaluated radiative lifetimes are of the order of nanoseconds. Furthermore, the a(3)Π→ X(1)Σ(+) transitions of BBr and BCl are also strongly diagonal and the X(1)Σ(+)→ A(1)Π transitions perhaps can be followed by the X(1)Σ(+)→ a(3)Π transitions to attain a lower Doppler temperature. Long-range behavior of BBr and BCl has also been studied, and a double well is found in the A(1)Π state of BBr. The shallow long-range well might open up even more channels for laser cooling of BBr. The results demonstrate the possibility of laser cooling BBr and BCl, and provide a promising theoretical reference for further research on BBr and BCl.
High-resolution spectroscopy on the laser-cooling candidate La^{-}.
Jordan, E; Cerchiari, G; Fritzsche, S; Kellerbauer, A
2015-09-11
The bound-bound transition from the 5d^{2}6s^{2} ^{3}F_{2}^{e} ground state to the 5d6s^{2}6p ^{3}D_{1}^{o} excited state in negative lanthanum has been proposed as a candidate for laser cooling, which has not yet been achieved for negative ions. Anion laser cooling holds the potential to allow the production of ultracold ensembles of any negatively charged species. We have studied the aforementioned transition in a beam of negative La ions by high-resolution laser spectroscopy. The center-of-gravity frequency was measured to be 96.592 80(10) THz. Seven of the nine expected hyperfine structure transitions were resolved. The observed peaks were unambiguously assigned to the predicted hyperfine transitions by a fit, confirmed by multiconfigurational self-consistent field calculations. From the determined hyperfine structure we conclude that La^{-} is a promising laser cooling candidate. Using this transition, only three laser beams would be required to repump all hyperfine levels of the ground state.
Wilson Fermions with Four Fermion Interactions
Rantaharju, Jarno; Pica, Claudio; Sannino, Francesco
2016-01-01
Four fermion interactions appear in many models of Beyond Standard Model physics. In Technicolour and composite Higgs models Standard Model fermion masses can be generated by four fermion terms. They are also expected to modify the dynamics of the new strongly interacting sector. In particular in technicolour models it has been suggested that they can be used to break infrared conformality and produce a walking theory with a large mass anomalous dimension. We study the SU(2) gauge theory with 2 adjoint fermions and a chirally symmetric four fermion term. We demonstrate chiral symmetry breaking at large four fermion coupling and study the phase diagram of the model.
Repumping and spectroscopy of laser-cooled Sr atoms using the (5s5p)3P2 - (5s4d)3D2 transition
Mickelson, P G; Anzel, P; DeSalvo, B J; Nagel, S B; Traverso, A J; Yan, M; Killian, T C
2009-01-01
We describe repumping and spectroscopy of laser-cooled strontium (Sr) atoms using the (5s5p)3P2 - (5s4d)3D2 transition. Atom number in a magneto-optical trap is enhanced by driving this transition because Sr atoms that have decayed into the (5s5p)3P2 dark state are repumped back into the (5s2)1S0 ground state. Spectroscopy of 84Sr, 86Sr, 87Sr, and 88Sr improves the value of the (5s5p)3P2 - (5s4d)3D2 transition frequency for 88Sr and determines the isotope shifts for the transition.
Wilson Fermions with Four Fermion Interactions
DEFF Research Database (Denmark)
Rantaharju, Jarno; Drach, Vincent; Hietanen, Ari;
2015-01-01
We present a lattice study of a four fermion theory, known as Nambu Jona-Lasinio (NJL) theory, via Wilson fermions. Four fermion interactions naturally occur in several extensions of the Standard Model as a low energy parameterisation of a more fundamental theory. In models of dynamical electrowe...
Laser cooling of the AlCl molecule with a three-electronic-level theoretical model
Wan, Mingjie; Yuan, Di; Jin, Chengguo; Wang, Fanhou; Yang, Yujie; Yu, You; Shao, Juxiang
2016-07-01
Feasibility of laser-cooling AlCl molecule is investigated using ab initio quantum chemistry. Potential energy curves, permanent dipole moments, and transition dipole moments for the X1Σ+, a3Π, and A1Π states are studied based on multi-reference configuration interaction plus Davidson corrections (MRCI+Q) method with ACVQZ basis set, spin-orbit coupling effects are considered at the MRCI+Q level. Highly diagonally distributed Franck-Condon factors (f00 = 0.9988 and f11 = 0.9970) and branching ratios (R00 = 0.9965, R01 = 2.85 × 10-3, R02 = 6.35 × 10-4, and R03 = 2.05 × 10-6) for the A 1 Π 1 ( ν ' = 0 ) → X 1 Σ0 + + ( ν ″ = 0 ) transition are determined. A sufficiently radiative lifetime τ (A1Π1) = 4.99 ns is predicted for rapid laser cooling. The proposed cooling wavelength is deep in the ultraviolet region at λ00 = 261.75 nm. Total emission rates for the a 3 Π 0 + → X 1 Σ0 + + , a 3 Π 1 → X 1 Σ0 + + , A1Π1 → a3Π0+, and A1Π1 → a3Π1 transitions are particularly small (˜10 s-1-650 s-1). The calculated vibrational branching loss ratio to the intermediate a3Π0+ and a3Π1 states can be negligible. The results imply the probability of laser cooling AlCl molecule with three-electronic-level.
The Laser Cooling and Magneto-Optical Trapping of the YO Molecule
Yeo, Mark
Laser cooling and magneto-optical trapping of neutral atoms has revolutionized the field of atomic physics by providing an elegant and efficient method to produce cold dense samples of ultracold atoms. Molecules, with their strong anisotropic dipolar interaction promises to unlock even richer phenomenon. However, due to their additional vibrational and rotational degrees of freedom, laser cooling techniques have only been extended to a small set of diatomic molecules. In this thesis, we demonstrate the first magneto-optical trapping of a diatomic molecule using a quasi-cycling transition and an oscillating quadrupole magnetic field. The transverse temperature of a cryogenically produced YO beam was reduced from 25 mK to 10 mK via doppler cooling and further reduced to 2 mK with the addition of magneto-optical trapping forces. The optical cycling in YO is complicated by the presence of an intermediate electronic state, as decays through this state lead to optical pumping into dark rotational states. Thus, we also demonstrate the mixing of rotational states in the ground electronic state using microwave radiation. This technique greatly enhances optical cycling, leading to a factor of 4 increase in the YO beam fluorescence and is used in conjunction with a frequency modulated and chirped continuous wave laser to longitudinally slow the YO beam. We generate YO molecules below 10 m/s that are directly loadable into a three-dimensional magneto-optical trap. This mixing technique provides an alternative to maintaining rotational closure and should extend laser cooling to a larger set of molecules.
Progress in rare-earth-doped nanocrystalline glass-ceramics for laser cooling
Venkata Krishnaiah, Kummara; Ledemi, Yannick; Soares de Lima Filho, Elton; Loranger, Sebastien; Nemova, Galina; Messaddeq, Younes; Kashyap, Raman
2016-03-01
Laser cooling with anti-Stokes fluorescencewas predicted by Pringsheim in 1929, but for solids was only demonstrated in 1995. There are many difficulties which have hindered laser assisted cooling, principally the chemical purity of a sample and the availability of suitable hosts. Recent progress has seen the cooled temperature plummet to 93K in Yb:YLF. One of the challenges for laser cooling to become ubiquitous, is incorporating the rare-earthcooling ion in a more easily engineered material, rather than a pure crystalline host. Rare-earth-doped nanocrystalline glass-ceramics were first developed by Wang and Ohwaki for enhanced luminescence and mechanical properties compared to their parent glasses. Our work has focused on creating a nanocrystalline environment for the cooling ion, in an easy to engineer glass. The glasses with composition 30SiO2-15Al2O3-27CdF2-22PbF2-4YF3-2YbF3 (mol%), have been prepared by the conventional melt-quenching technique. By a simple post fabrication thermal treatment, the rare-earth ions are embedded in the crystalline phase within the glass matrix. Nanocrystals with various sizes and rare-earth concentrations have been fabricated and their photoluminescence properties assessed in detail. These materials show close to unity photoluminescence quantum yield (PLQY) when pumped above the band. However, they exhibit strong up-conversion into the blue, characteristic of Tm trace impurity whose presence was confirmed. The purification of the starting materials is underway to reduce the background loss to demonstrate laser cooling. Progress in the development of these nano-glass-ceramics and their experimental characterization will be discussed.
Laser cooling of the AlCl molecule with a three-electronic-level theoretical model.
Wan, Mingjie; Yuan, Di; Jin, Chengguo; Wang, Fanhou; Yang, Yujie; Yu, You; Shao, Juxiang
2016-07-14
Feasibility of laser-cooling AlCl molecule is investigated using ab initio quantum chemistry. Potential energy curves, permanent dipole moments, and transition dipole moments for the X(1)Σ(+), a(3)Π, and A(1)Π states are studied based on multi-reference configuration interaction plus Davidson corrections (MRCI+Q) method with ACVQZ basis set, spin-orbit coupling effects are considered at the MRCI+Q level. Highly diagonally distributed Franck-Condon factors (f00 = 0.9988 and f11 = 0.9970) and branching ratios (R00 = 0.9965, R01 = 2.85 × 10(-3), R02 = 6.35 × 10(-4), and R03 = 2.05 × 10(-6)) for the A(1)Π1(ν(')=0)→X(1)Σ0(+) (+)(ν(″)=0) transition are determined. A sufficiently radiative lifetime τ (A(1)Π1) = 4.99 ns is predicted for rapid laser cooling. The proposed cooling wavelength is deep in the ultraviolet region at λ00 = 261.75 nm. Total emission rates for the a(3)Π0(+) →X(1)Σ0(+) (+), a(3)Π1→X(1)Σ0(+) (+), A(1)Π1 → a(3)Π0(+) , and A(1)Π1 → a(3)Π1 transitions are particularly small (∼10 s(-1)-650 s(-1)). The calculated vibrational branching loss ratio to the intermediate a(3)Π0(+) and a(3)Π1 states can be negligible. The results imply the probability of laser cooling AlCl molecule with three-electronic-level.
Optimization of transfer of laser-cooled atom cloud to a quadrupole magnetic
Indian Academy of Sciences (India)
S P Ram; S K Tiwari; S R Mishra; H S Rawat
2014-02-01
We present here our experimental results on transfer of laser-cooled atom cloud to a quadrupole magnetic trap. We show that by choosing appropriately the ratio of potential energy in magnetic trap to kinetic energy of cloud in molasses, we can obtain the maximum phase-space density in the magnetic trap. These results guide us to choose the value of current to be switched in the quadrupole coils used for magnetic trapping for a given temperature of the cloud after molasses. This study is also useful to set the initial phase-space density of the cloud before evaporative cooling.
Rotational state microwave mixing for laser cooling of complex diatomic molecules
Yeo, Mark; Collopy, Alejandra L; Yan, Bo; Hemmerling, Boerge; Chae, Eunmi; Doyle, John M; Ye, Jun
2015-01-01
We demonstrate the mixing of rotational states in the ground electronic state using microwave radiation to enhance optical cycling in the molecule yttrium (II) monoxide (YO). This mixing technique is used in conjunction with a frequency modulated and chirped continuous wave laser to slow longitudinally a cryogenic buffer gas beam of YO. We generate a measurable flux of YO below 10~m/s, directly loadable into a three-dimensional magneto-optical trap. This technique opens the door for laser cooling of molecules with more complex structure.
Rotational State Microwave Mixing for Laser Cooling of Complex Diatomic Molecules
Yeo, Mark; Hummon, Matthew T.; Collopy, Alejandra L.; Yan, Bo; Hemmerling, Boerge; Chae, Eunmi; Doyle, John M.; Ye, Jun
2015-06-01
We demonstrate the mixing of rotational states in the ground electronic state using microwave radiation to enhance optical cycling in the molecule yttrium (II) monoxide (YO). This mixing technique is used in conjunction with a frequency modulated and chirped continuous wave laser to slow longitudinally a cryogenic buffer-gas beam of YO. We generate a flux of YO below 10 m /s , directly loadable into a three-dimensional magneto-optical trap. This technique opens the door for laser cooling of diatomic molecules with more complex loss channels due to intermediate states.
Arduino-based laboratory instruments for an undergraduate laser cooling experiment
Ireland, Timothy; Tiber, Gage; Brooke, Robert W. A.; Gillis, Julie M.; Zaccagnini, Christopher A.; Corcovilos, Theodore A.
2015-05-01
Arduino is an inexpensive open-source microcontroller platform designed for quick development turn-around and easy interfacing, making it ideal for novice programmers and instrument designers. Based on Atmel ATMEGA microcontroller chips, the Arduino boards are programmed with standard C/C++ code and contain sufficient inputs and outputs (both digital and analog) for basic data acquisition and device control. Here we present home-built Arduino-based instruments commonly used in laser-cooling experiments, such as a wavelength meter and temperature controller. We describe the design and performance of these instruments.
Temperature Measurements of Laser-Cooled Ions in a Penning Trap
Jensen, M. J.; Hasegawa, T.; Bollinger, J. J.
2003-12-01
Between 104 and 106 9Be+ ions are trapped in a Penning trap. The ions are laser-cooled to ˜millikelvin temperatures, where they form ion crystals. This system is an example of a strongly coupled one-component plasma. By means of Doppler laser spectroscopy we have measured the temperature and heating rate of the plasma. Initially the heating rate is low, 60 ± 40 mK/s, but after about 100 ms the plasma heats up rapidly to a few kelvin. The onset of the rapid heating coincides with the solid-liquid phase transition.
Enhanced Laser Cooling of Rare-Earth-Ion-Doped Composite Material
Institute of Scientific and Technical Information of China (English)
JIA You-Hua; ZHONG Biao; JI Xian-Ming; YIN Jian-Ping
2008-01-01
We predict enhanced laser cooling performance of rare-earth-ions-doped glasses containing nanometre-sized ultrafine particles, which can be achieved by the enhancement of local field around rare earth ions, owing to the surface plasma resonance of small metallic particles. The influence of energy transfer between ions and the particle is theoretically discussed. Depending on the particle size and the ion emission quantum efficiency, the enhancement of the absorption is predicted. It is concluded that the absorption are greatly enhanced in these composite materials, the cooling power is increased as compared to the bulk material.
A compact and efficient strontium oven for laser-cooling experiments
Schioppo, M.; Poli, N.; M. Prevedelli; Falke, St.; Lisdat, Ch.; Sterr, U.; G. M. Tino
2012-01-01
Here we describe a compact and efficient strontium oven well suited for laser-cooling experiments. Novel design solutions allowed us to produce a collimated strontium atomic beam with a flux of 1.0\\times10^13 s^-1 cm^-2 at the oven temperature of 450 {\\deg}C, reached with an electrical power consumption of 36 W. The oven is based on a stainless-steel reservoir, filled with 6 g of metallic strontium, electrically heated in a vacuum environment by a tantalum wire threaded through an alumina mul...
Laser-cooled atoms inside a hollow-core photonic-crystal fiber
DEFF Research Database (Denmark)
Bajcsy, Michal; Hofferberth, S.; Peyronel, Thibault
2011-01-01
We describe the loading of laser-cooled rubidium atoms into a single-mode hollow-core photonic-crystal fiber. Inside the fiber, the atoms are confined by a far-detuned optical trap and probed by a weak resonant beam. We describe different loading methods and compare their trade-offs in terms...... of implementation complexity and atom-loading efficiency. The most efficient procedure results in loading of ∼30,000 rubidium atoms, which creates a medium with an optical depth of ∼180 inside the fiber. Compared to our earlier study this represents a sixfold increase in the maximum achieved optical depth...
Dick Effect in a Microwave Frequency Standard Based on Laser-Cooled 113Cd+ Ions
Zhang, Jian-Wei; Miao, Kai; Wang, Li-Jun
2015-01-01
The Dick effect is one of the main limits to the frequency stability of a passive frequency standard, especially for the fountain clock and ion clock operated in pulsed mode which require unavoidable dead time during interrogation. Here we measure the phase noise of the interrogation oscillator applied in the microwave frequency standard based on laser-cooled 113Cd+ ions, and analyze the Allan deviation limited by the Dick effect. The results indicate that the Dick effect is one of the key issues for the cadmium ion clock to reach expected frequency stability. This problem can be resolved by interrogating the local oscillator continuously with two ion traps.
Pulsed Sisyphus scheme for laser cooling of atomic (anti)hydrogen.
Wu, Saijun; Brown, Roger C; Phillips, William D; Porto, J V
2011-05-27
We propose a laser cooling technique in which atoms are selectively excited to a dressed metastable state whose light shift and decay rate are spatially correlated for Sisyphus cooling. The case of cooling magnetically trapped (anti)hydrogen with the 1S-2S-3P transitions by using pulsed ultraviolet and continuous-wave visible lasers is numerically simulated. We find a number of appealing features including rapid three-dimensional cooling from ∼1 K to recoil-limited, millikelvin temperatures, as well as suppressed spin-flip loss and manageable photoionization loss. © 2011 American Physical Society
Photothermal self-oscillation and laser cooling of graphene optomechanical systems.
Barton, Robert A; Storch, Isaac R; Adiga, Vivekananda P; Sakakibara, Reyu; Cipriany, Benjamin R; Ilic, B; Wang, Si Ping; Ong, Peijie; McEuen, Paul L; Parpia, Jeevak M; Craighead, Harold G
2012-09-12
By virtue of their low mass and stiffness, atomically thin mechanical resonators are attractive candidates for use in optomechanics. Here, we demonstrate photothermal back-action in a graphene mechanical resonator comprising one end of a Fabry-Perot cavity. As a demonstration of the utility of this effect, we show that a continuous wave laser can be used to cool a graphene vibrational mode or to power a graphene-based tunable frequency oscillator. Owing to graphene's high thermal conductivity and optical absorption, photothermal optomechanics is efficient in graphene and could ultimately enable laser cooling to the quantum ground state or applications such as photonic signal processing.
Ab initio study on the electronic states and laser cooling of AlCl and AlBr
Rong, Yang; Bin, Tang; Tao, Gao
2016-04-01
We investigate whether AlCl and AlBr are promising candidates for laser cooling. We report new ab initio calculations on the ground state X1Σ+ and two low-lying states (A1Π and a3Π) of AlCl and AlBr. The calculated spectroscopic constants show good agreement with available theoretical and experimental results. We also obtain the permanent dipole moments (PDMs) curve at multi-reference configuration interaction (MRCI) level of theory. The transition properties of A1Π and a3Π states are predicted, including the transition dipole moments (TDMs), Franck-Condon factors (FCFs), radiative times and radiative width. The calculated radiative lifetimes are of the order of a nanosecond, implying that they are sufficiently short for rapid laser cooling. Both AlCl and AlBr have highly diagonally distributed FCFs which are crucial requirement for molecular laser cooling. The results demonstrate the feasibility of laser cooling AlCl and AlBr, and we propose laser cooling schemes for AlCl and AlBr.
A Laser-Cooled Ion Source to Sympathetically Cool Positrons in the ALPHA Experiment
Sameed, Muhammed; Maxwell, Daniel; Madsen, Niels
2016-10-01
The ALPHA experiment at CERN studies the properties of antimatter by making precision measurements on antihydrogen. Antihydrogen atoms are produced by mixing a cloud of cold antiprotons with a dense positron plasma inside a magnetic trap. The formation of antihydrogen, of which only the coldest atoms remain trapped, depends principally on the kinetic energy of the constituent plasmas. Presently, the trapping rate is approximately two atoms in a seven minute cycle. During mixing, the antiprotons thermalize in the positron plasma prior to antihydrogen production. Colder positron temperatures would therefore result in an increased fraction of trapped antihydrogen atoms in the ALPHA mixing trap. At present, the positrons used for antihydrogen production in ALPHA reach energies of about 50 K. Much colder positron plasmas may be achieved by sympathetically cooling the positrons using laser-cooled beryllium ions. Preliminary results in the development of a low flux and low energy beryllium ion source using a pulsed ablation laser are presented. Precision ablation techniques coupled with laser-cooling can subsequently be used to effectively cool positrons. A provisional design of an ablation source is also presented for installation in the ALPHA apparatus in 2017. The authors would like to thank EPSRC for supporting this research.
Structure, branching ratios, and a laser-cooling scheme for the 138BaF molecule
Chen, Tao; Bu, Wenhao; Yan, Bo
2016-12-01
For laser-cooling considerations, we have theoretically investigated the electronic, rovibrational, and hyperfine structures of the BaF molecule. The highly diagonal Franck-Condon factors and the branching ratios for all possible transitions within the lowest-lying four electronic states have also been calculated. Meanwhile, the mixing between the metastable A'2Δ and A2Π states and, further, the lifetime of the Δ state have been estimated since the loss procedure via the Δ state might fatally break the main quasicycling Σ -Π transition for cooling and trapping. The resultant hyperfine splittings of each rovibrational state in the X2Σ+ state provide benchmarks for sideband modulations of the cooling and repumping lasers and the remixing microwaves to address all necessary levels. The calculated Zeeman shift and g factors for both X and A states serve as benchmarks for selection of the trapping laser polarizations. Our study paves the way for future laser cooling and magneto-optical trapping of the BaF molecule.
Laser cooling of MgCl and MgBr in theoretical approach
Energy Technology Data Exchange (ETDEWEB)
Wan, Mingjie; Shao, Juxiang; Huang, Duohui; Yang, Junsheng; Cao, Qilong; Jin, Chengguo; Wang, Fanhou, E-mail: fanhouwangyibin@163.com [Computational Physics Key Laboratory of Sichuan Province, Yibin University, Yibin 644007 (China); Gao, Yufeng [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China)
2015-07-14
Ab initio calculations for three low-lying electronic states (X{sup 2}Σ{sup +}, A{sup 2}Π, and 2{sup 2}Π) of MgCl and MgBr molecules, including spin-orbit coupling, are performed using multi-reference configuration interaction plus Davidson correction method. The calculations involve all-electronic basis sets and Douglas–Kroll scalar relativistic correction. Spectroscopic parameters well agree with available theoretical and experimental data. Highly diagonally distributed Franck-Condon factors f{sub 00} for A{sup 2}Π{sub 3/2,1/2} (υ′ = 0) → X{sup 2}Σ{sup +}{sub 1/2} (υ″ = 0) are determined for both MgCl and MgBr molecules. Suitable radiative lifetimes τ of A{sup 2}Π{sub 3/2,1/2} (υ′ = 0) states for rapid laser cooling are also obtained. The proposed laser drives A{sup 2}Π{sub 3/2} (υ′ = 0) → X{sup 2}Σ{sup +}{sub 1/2} (υ″ = 0) transition by using three wavelengths (main pump laser λ{sub 00}; two repumping lasers λ{sub 10} and λ{sub 21}). These results indicate the probability of laser cooling MgCl and MgBr molecules.
Bright focused ion beam sources based on laser-cooled atoms
McClelland, J J; Knuffman, B; Twedt, K A; Schwarzkopf, A; Wilson, T M
2015-01-01
Nanoscale focused ion beams (FIBs) represent one of the most useful tools in nanotechnology, enabling nanofabrication via milling and gas-assisted deposition, microscopy and microanalysis, and selective, spatially resolved doping of materials. Recently, a new type of FIB source has emerged, which uses ionization of laser cooled neutral atoms to produce the ion beam. The extremely cold temperatures attainable with laser cooling (in the range of 100 uK or below) result in a beam of ions with a very small transverse velocity distribution. This corresponds to a source with extremely high brightness that rivals or may even exceed the brightness of the industry standard Ga+ liquid metal ion source. In this review we discuss the context of ion beam technology in which these new ion sources can play a role, their principles of operation, and some examples of recent demonstrations. The field is relatively new, so only a few applications have been demonstrated, most notably low energy ion microscopy with Li ions. Never...
A novel detection system for laser cooling of ortho-positronium
Mondal, N K
2002-01-01
We report on the development of a position-sensitive scintillation detector system for viewing laser-cooled ortho-positronium (oPs) annihilation points. Ortho-positronium can be cooled down to a recoil limit of 0.1 K by an ultraviolet laser in spite of its relatively short lifetime. In order to perform this experiment the wavelength of Cr:LiSAF laser is considered to be 243 nm which corresponds to the transition energy of 1S-2P states of oPs. Thermal positronium plays an important role in laser cooling of oPs. We investigated various kinds and sizes of inorganic scintillators. Position resolutions of YAP:Ce and CsI(Tl), respectively, were determined to be 3.00 and 3.8 mm. Extensive Monte Carlo simulation studies were performed to view the decay positions of oPs using the time-of-flight method. Related issues of position resolution measurements and oPs decaying points will be discussed.
A novel detection system for laser cooling of ortho-positronium
Mondal, Nagendra Nath
2002-12-01
We report on the development of a position-sensitive scintillation detector system for viewing laser-cooled ortho-positronium (oPs) annihilation points. Ortho-positronium can be cooled down to a recoil limit of 0.1 K by an ultraviolet laser in spite of its relatively short lifetime. In order to perform this experiment the wavelength of Cr:LiSAF laser is considered to be 243 nm which corresponds to the transition energy of 1S-2P states of oPs. Thermal positronium plays an important role in laser cooling of oPs. We investigated various kinds and sizes of inorganic scintillators. Position resolutions of YAP:Ce and CsI(Tl), respectively, were determined to be 3.00 and 3.8 mm. Extensive Monte Carlo simulation studies were performed to view the decay positions of oPs using the time-of-flight method. Related issues of position resolution measurements and oPs decaying points will be discussed.
Bright focused ion beam sources based on laser-cooled atoms
McClelland, J. J.; Steele, A. V.; Knuffman, B.; Twedt, K. A.; Schwarzkopf, A.; Wilson, T. M.
2016-01-01
Nanoscale focused ion beams (FIBs) represent one of the most useful tools in nanotechnology, enabling nanofabrication via milling and gas-assisted deposition, microscopy and microanalysis, and selective, spatially resolved doping of materials. Recently, a new type of FIB source has emerged, which uses ionization of laser cooled neutral atoms to produce the ion beam. The extremely cold temperatures attainable with laser cooling (in the range of 100 μK or below) result in a beam of ions with a very small transverse velocity distribution. This corresponds to a source with extremely high brightness that rivals or may even exceed the brightness of the industry standard Ga+ liquid metal ion source. In this review we discuss the context of ion beam technology in which these new ion sources can play a role, their principles of operation, and some examples of recent demonstrations. The field is relatively new, so only a few applications have been demonstrated, most notably low energy ion microscopy with Li ions. Nevertheless, a number of promising new approaches have been proposed and/or demonstrated, suggesting that a rapid evolution of this type of source is likely in the near future. PMID:27239245
Laser cooling of MgCl and MgBr in theoretical approach.
Wan, Mingjie; Shao, Juxiang; Gao, Yufeng; Huang, Duohui; Yang, Junsheng; Cao, Qilong; Jin, Chengguo; Wang, Fanhou
2015-07-14
Ab initio calculations for three low-lying electronic states (X(2)Σ(+), A(2)Π, and 2(2)Π) of MgCl and MgBr molecules, including spin-orbit coupling, are performed using multi-reference configuration interaction plus Davidson correction method. The calculations involve all-electronic basis sets and Douglas-Kroll scalar relativistic correction. Spectroscopic parameters well agree with available theoretical and experimental data. Highly diagonally distributed Franck-Condon factors f00 for A(2)Π3/2,1/2 (υ' = 0) → X(2)Σ(+) 1/2 (υ″ = 0) are determined for both MgCl and MgBr molecules. Suitable radiative lifetimes τ of A(2)Π3/2,1/2 (υ' = 0) states for rapid laser cooling are also obtained. The proposed laser drives A(2)Π3/2 (υ' = 0) → X(2)Σ(+) 1/2 (υ″ = 0) transition by using three wavelengths (main pump laser λ00; two repumping lasers λ10 and λ21). These results indicate the probability of laser cooling MgCl and MgBr molecules.
Liu, Jianbin; Zheng, Huaibin; Chen, Hui; Li, Fu-li; Xu, Zhuo
2016-01-01
Ghost imaging with thermal fermions is calculated based on two-particle interference in Feynman's path integral theory. It is found that ghost imaging with thermal fermions can be simulated by ghost imaging with thermal bosons and classical particles. Photons in pseudothermal light are employed to experimentally study fermionic ghost imaging. Ghost imaging with thermal bosons and fermions is discussed based on the point-to-point (spot) correlation between the object and image planes. The employed method offers an efficient guidance for future ghost imaging with real thermal fermions, which may also be generalized to study other second-order interference phenomena with fermions.
Li, Xiao-Ni; Wen, Wei-Qiang; Du, Heng; Li, Peng; Zhang, Xiao-Hu; Hu, Xue-Jing; Qu, Guo-Feng; Li, Zhong-Shan; Ge, Wen-Wen; Li, Jie; Wang, Han-Bing; Xia, Jia-Wen; Yang, Jian-Cheng; Ma, Xin-Wen; Yuan, You-Jin
2017-07-01
Laser cooling of Li-like C3+ and O4+ relativistic heavy ion beams is planned at the experimental Cooler Storage Ring (CSRe). Recently, a preparatory experiment to test important prerequisites for laser cooling of relativistic 12C3+ ion beams using a pulsed laser system has been performed at the CSRe. Unfortunately, the interaction between the ions and the pulsed laser cannot be detected. In order to study the laser cooling process and find the optimized parameters for future laser cooling experiments, a multi-particle tracking method has been developed to simulate the detailed longitudinal dynamics of laser-cooled ion beams at the CSRe. Simulations of laser cooling of the 12C3+ion beams by scanning the frequency of the RF-buncher or continuous wave (CW) laser wavelength have been performed. The simulation results indicate that ion beams with a large momentum spread could be laser-cooled by the combination of only one CW laser and the RF-buncher, and show the requirements of a successful laser cooling experiment. The optimized parameters for scanning the RF-buncher frequency or laser frequency have been obtained. Furthermore, the heating effects have been estimated for laser cooling at the CSRe. The Schottky noise spectra of longitudinally modulated and laser-cooled ion beams have been simulated to fully explain and anticipate the experimental results. The combination of Schottky spectra from the highly sensitive resonant Schottky pick-up and the simulation methods developed in this paper will be helpful to investigate the longitudinal dynamics of RF-bunched and ultra-cold ion beams in the upcoming laser cooling experiments at the CSRe. Supported by National Natural Science Foundation of China (11405237, 11504388)
Sympathetic laser-cooling of graphene with Casimir-Polder forces
Ribeiro, Sofia
2016-01-01
We propose a scheme to actively cool the fundamental flexural (out-of-plane) mode of a graphene sheet via vacuum forces. Our setup consists in a cold atom cloud placed close to a graphene sheet at distances of a few micrometers. The atoms couple to the graphene membrane via Casimir-Polder forces. By deriving a self-consistent set of equations governing the dynamics of the atomic gas and the flexural modes of the graphene, we show to be possible to cool graphene from room temperatures by actively (laser) cooling an atomic gas. By choosing the right set of experimental parameter we are able to cool a graphene sheet down to ~ 60 microkelvin.
New directions in direct laser cooling and trapping of diatomic molecules
Steinecker, Matthew; McCarron, Daniel; Norrgard, Eric; Edwards, Eustace; Demille, David
2015-05-01
In recent years, tremendous progress has been made in laser cooling and trapping of molecules. With the achievement of a magneto-optical trap (MOT) for the diatomic molecule SrF, a range of novel experiments employing ultracold molecules may be within reach. Here we present planned improvements to our SrF MOT apparatus, including plans for more efficient MOT loading, sub-Doppler cooling, loading into a conservative trap, and co-trapping of atoms. These and other improvements should allow increases in trapped molecule number, lifetime, and phase-space density. We illustrate some of the experiments that will be enabled by these improvements, such as studies of inelastic and reactive atom-molecule collisions at ultracold temperatures and investigations of sympathetic and evaporative cooling of SrF.
A cryogenic beam apparatus for laser cooling and ultracold fragmentation of BaH molecules
Iwata, Geoffrey; Tarallo, Marco G.; Soerensen, Fabian; Zelevinsky, Tanya
2015-05-01
Cold and ultracold molecules offer a wide array of possibilities for precision measurement, molecular quantum chemistry, and studies many-body physics. Recently, cold beams of many molecular species have been created via cryogenic buffer gas cooling. Paired with laser cooling, this method can yield a molecular magneto-optical trap (MOT). We report progress toward a barium monohydride (BaH) cold molecular beam and MOT, including identification of cooling transitions in the B2 Σ molecules and construction of the cryogenic beam apparatus. The large mass ratio of the constituent atoms makes this system attractive for studies of ultracold fragmentation via coherent transfer to weakly bound states and subsequent photo- or magneto-dissociation, resulting in ultracold hydrogen.
Kaufman, Adam
2016-05-01
Motional control of neutral atoms has a rich history and increasingly interest has turned to single-atom control. In my thesis work, we created a platform to individually prepare single bosonic atoms in highly pure quantum states, by developing methods to laser cool single atoms to the vibrational ground state of optical tweezer traps. Applying this toolset, we observe the atomic Hong-Ou-Mandel effect when we arrange for atom tunneling to play the role of a balanced beam splitter between two optical tweezers. In another experiment, we utilize spin exchange to create entanglement, which we then verify after spatially separating the atoms to observe their non-local correlations. Merging these results with our recent demonstration of deterministic loading of atomic arrays, our results establish the concept of quantum gas assembly, which could be applied to a variety of systems ranging from the production of single dipolar molecules to the assembly of low-entropy arrays of atoms.
Microwave lensing frequency shift of the PHARAO laser-cooled microgravity atomic clock
Peterman, Phillip; Gibble, Kurt; Laurent, Phillipe; Salomon, Christophe
2016-04-01
We evaluate the microwave lensing frequency shift of the microgravity laser-cooled caesium clock PHARAO. We find microwave lensing frequency shifts of δν/ν = 11 × 10-17 to 13 × 10-17, larger than the shift of typical fountain clocks. The shift has a weak dependence on PHARAO parameters, including the atomic temperature, size of the atomic cloud, detection laser intensities, and the launch velocity. We also find the lensing frequency shift to be insensitive to selection and detection spatial inhomogeneities and the expected low-frequency vibrations. We conservatively assign a nominal microwave lensing frequency uncertainty of ±4 × 10-17.
Femtosecond quantum dynamics and laser-cooling in thermal molecular systems
Warmuth, C
2000-01-01
of thermal trans-stilbene upon excitation at the omega sub 0 frequency. The experimental results are in good agreement with theoretical analysis. This work deals with coherent and incoherent vibrational phenomena in thermal systems, wave packet motion and laser-cooling. In the first part, the principle of COIN (Coherence Observation by Interference Noise) has been applied as a new approach to measuring wave packet motion. In the experiment pairs of phase-randomized femtosecond pulses with relative delay-time tau prepare interference fluctuations in the excited state population, so the variance of the correlated fluorescence intensity directly mimics the dynamics of the propagating wave packet. The scheme is demonstrated by measuring the vibrational coherence of wave packet-motion in the B-state of gaseous iodine. The COIN-interferograms obtained recover propagation, recurrences, spreading, and revivals as the typical signature of wave packets. Due to the disharmony of the B-state-potential, fractional revival...
Laser cooling of a micromechanical membrane to the quantum backaction limit
Peterson, R W; Kampel, N S; Andrews, R W; Yu, P -L; Lehnert, K W; Regal, C A
2015-01-01
The radiation pressure of light can act to damp and cool the vibrational motion of a mechanical resonator. In understanding the quantum limits of this cooling, one must consider the effect of shot noise fluctuations on the final thermal occupation. In optomechanical sideband cooling in a cavity, the finite Stokes Raman scattering defined by the cavity linewidth combined with shot noise fluctuations dictates a quantum backaction limit, analogous to the Doppler limit of atomic laser cooling. In our work we sideband cool to the quantum backaction limit by using a micromechanical membrane precooled in a dilution refrigerator. Monitoring the optical sidebands allows us to directly observe the mechanical object come to thermal equilibrium with the optical bath.
Enhanced Laser Cooling of Rare-Earth-Ion-Doped Glass Containing Nanometer-Sized Metallic Particles
Institute of Scientific and Technical Information of China (English)
JIA You-Hun; ZHONG Biao; YIN Jian-Ping
2009-01-01
The enhanced laser cooling performance of rare-earth-ions-doped glasses containing small particles is predicted. This is achieved by the enhancement of local field around rare earth ions, owing to the surface plasmon resonance of small metallic particles. The role of energy transfer between ions and the particle is theoretical discussed. Depending on the particle size and the ion emission quantum efficiency, the enhancement of the absorption and the fluorescence is predicted. Moreover, taking Yb3+-doped ZBLAN as example, the cooling power and heat-light converting efficiency are calculated. It is finally concluded that the absorption and the fluorescence are greatly enhanced in these composite materials, the cooling power is increased compared to the bulk material.
A compact and efficient strontium oven for laser-cooling experiments.
Schioppo, M; Poli, N; Prevedelli, M; Falke, St; Lisdat, Ch; Sterr, U; Tino, G M
2012-10-01
Here we describe a compact and efficient strontium oven well suited for laser-cooling experiments. Novel design solutions allowed us to produce a collimated strontium atomic beam with a flux of 1.0 × 10(13) s(-1) cm(-2) at the oven temperature of 450 °C, reached with an electrical power consumption of 36 W. The oven is based on a stainless-steel reservoir, filled with 6 g of metallic strontium, electrically heated in a vacuum environment by a tantalum wire threaded through an alumina multi-bore tube. The oven can be hosted in a standard DN40CF cube and has an estimated continuous operation lifetime of 10 years. This oven can be used for other alkali and alkaline earth metals with essentially no modifications.
A compact and efficient strontium oven for laser-cooling experiments
Schioppo, Marco; Prevedelli, Marco; Falke, Stephan; Lisdat, Christian; Sterr, Uwe; Tino, Guglielmo Maria
2012-01-01
Here we describe a compact and efficient strontium oven well suited for laser-cooling experiments. Novel design solutions allowed us to produce a collimated strontium atomic beam with a flux of 1.0\\times10^13 s^-1 cm^-2 at the oven temperature of 450 {\\deg}C, reached with an electrical power consumption of 36 W. The oven is based on a stainless-steel reservoir, filled with 6 g of metallic strontium, electrically heated in a vacuum environment by a tantalum wire threaded through an alumina multi-bore tube. The oven can be hosted in a standard DN40CF cube and has an estimated continuous operation lifetime of 10 years. This oven can be used for other alkali and alkaline earth metals with essentially no modifications.
Radiation pressure and laser cooling of a three-level atom in a ladder configuration
Institute of Scientific and Technical Information of China (English)
Tan Lei; Wang Zhi-Cheng; Gu Huai-Qiang
2004-01-01
Radiation pressure and laser cooling of a moving three-level ladder-type atom in bichromatic travelling fields are considered. The dependence of the force on parameters such as detunings, Rabi frequencies and spontaneous decay rates is calculated numerically and shown graphically, and analytical expressions for the force are obtained for some special parameter values. It is shown that the radiation pressure shows Doppler-shifted resonance peaks resulting respectively from one-photon and two-photon transitions. Using the present scheme, Doppler cooling of sodium exploiting the 3 2S1/2-3 2P3/2-3 2D5/2 cascade transitions is investigated. It is found that temperatures lower than the Doppler limit can be achieved.
Temperature limits in laser cooling of free atoms with three-level cascade transitions
Cruz, Flavio C; Magno, Wictor C
2013-01-01
We employ semiclassical theoretical analysis to study laser cooling of free atoms using three-level cascade transitions, where the upper transition is much weaker than the lower one. This represents an alternate cooling scheme, particularly useful for group II atoms. We find that temperatures below the Doppler limits associated with each of these transitions are expected. The lowest temperatures arise from a remarkable increase in damping and reduced diffusion compared to two-level cooling. They are reached at the two-photon resonance, where there is a crossing between the narrow and the partially-dark dressed states, and can be estimated simply by the usual Doppler limit considering the decay rate of the optical coherence between these states.
Narrowband solid state vuv coherent source for laser cooling of antihydrogen
Energy Technology Data Exchange (ETDEWEB)
Michan, J. Mario [TRIUMF (Canada); Polovy, Gene; Madison, Kirk W. [The University of British Columbia, Department of Physics and Astronomy (Canada); Fujiwara, Makoto C. [TRIUMF (Canada); Momose, Takamasa, E-mail: momose@chem.ubc.ca [The University of British Columbia, Department of Chemistry, Department of Physics and Astronomy (Canada)
2015-11-15
We describe the design and performance of a solid-state pulsed source of narrowband (< 100 MHz) Lyman-α radiation designed for the purpose of laser cooling magnetically trapped antihydrogen. Our source utilizes an injection seeded Ti:Sapphire amplifier cavity to generate intense radiation at 729.4 nm, which is then sent through a frequency doubling stage and a frequency tripling stage to generate 121.56 nm light. Although the pulse energy at 121.56 nm is currently limited to 12 nJ with a repetition rate of 10 Hz, we expect to obtain greater than 0.1 μJ per pulse at 10 Hz by further optimizing the alignment of the pulse amplifier and the efficiency of the frequency tripling stage. Such a power will be sufficient for cooling a trapped antihydrogen atom from 500 mK to 20mK.
Laser Cooling of a Micromechanical Membrane to the Quantum Backaction Limit.
Peterson, R W; Purdy, T P; Kampel, N S; Andrews, R W; Yu, P-L; Lehnert, K W; Regal, C A
2016-02-12
The radiation pressure of light can act to damp and cool the vibrational motion of a mechanical resonator, but even if the light field has no thermal component, shot noise still sets a limit on the minimum phonon occupation. In optomechanical sideband cooling in a cavity, the finite off-resonant Stokes scattering defined by the cavity linewidth combined with shot noise fluctuations dictates a quantum backaction limit, analogous to the Doppler limit of atomic laser cooling. In our work, we sideband cool a micromechanical membrane resonator to the quantum backaction limit. Monitoring the optical sidebands allows us to directly observe the mechanical object come to thermal equilibrium with the optical bath. This level of optomechanical coupling that overwhelms the intrinsic thermal decoherence was not reached in previous ground-state cooling demonstrations.
Energy Technology Data Exchange (ETDEWEB)
Holberg, Leo; Mills, Allen [NIST
2008-08-30
Leo Holberg and Allen Mills present a talk at Frontiers in Laser Cooling, Single-Molecule Biophysics and Energy Science, a scientific symposium honoring Steve Chu, director of Lawrence Berkeley National Laboratory and recipient of the 1997 Nobel Prize in Physics. The symposium was held August 30, 2008 in Berkeley.
Wilson Fermions with Four Fermion Interactions
Rantaharju, Jarno; Hietanen, Ari; Pica, Claudio; Sannino, Francesco
2015-01-01
We present a lattice study of a four fermion theory, known as Nambu Jona-Lasinio (NJL) theory, via Wilson fermions. Four fermion interactions naturally occur in several extensions of the Standard Model as a low energy parameterisation of a more fundamental theory. In models of dynamical electroweak symmetry breaking these operators, at an effective level, are used to endow the Standard Model fermions with masses. Furthermore these operators, when sufficiently strong, can drastically modify the fundamental composite dynamics by, for example, turning a strongly coupled infrared conformal theory into a (near) conformal one with desirable features for model building. As first step, we study spontaneous chiral symmetry breaking for the lattice version of the NJL model.
Redkov, V M
1999-01-01
The paper concerns a problem of the Dirac fermion doublet in the external monopole potential obtained by embedding the Abelian monopole solution in the non-Abelian scheme. In this case, the doublet-monopole Hamiltonian is invariant under operations consisting of a complex and one parametric Abelian subgroup in S0(3.C). This symmetry results in a certain freedom in choosing a discrete operator N(A) (A is a complex number) entering the complete set of quantum variables. The same complex number A represents an additional parameter at the basis functions. The generalized inversion like operator N(A) affords certain generalized N(A)-parity selection rules. All the different sets of basis functions Psi(A) determine the same Hilbert space. The functions Psi(A) decompose into linear combinations of Psi(A=0): Psi(A) = F(A) Psi(A=0). However, the bases considered turn out to be nonorthogonal ones when A is a complex number; the latter correlates with the non-self-conjugacy of the N(A) at complex A-s. The meaning of pos...
Staggered domain wall fermions
Hoelbling, Christian
2016-01-01
We construct domain wall fermions with a staggered kernel and investigate their spectral and chiral properties numerically in the Schwinger model. In some relevant cases we see an improvement of chirality by more than an order of magnitude as compared to usual domain wall fermions. Moreover, we present first results for four-dimensional quantum chromodynamics, where we also observe significant reductions of chiral symmetry violations for staggered domain wall fermions.
Fermion field renormalization prescriptions
Zhou, Yong
2005-01-01
We discuss all possible fermion field renormalization prescriptions in conventional field renormalization meaning and mainly pay attention to the imaginary part of unstable fermion Field Renormalization Constants (FRC). We find that introducing the off-diagonal fermion FRC leads to the decay widths of physical processes $t\\to c Z$ and $b\\to s \\gamma$ gauge-parameter dependent. We also discuss the necessity of renormalizing the bare fields in conventional quantum field theory.
Fermions as topological objects
Yershov, V N
2002-01-01
A conceptual preon-based model of fermions is discussed. The preon is regarded as a topological object with three degrees of freedom in a dual three-dimensional manifold. It is shown that properties of this manifold give rise to a set of preon structures, which resemble three families of fermions. The number of preons in each structure is easily associated with the mass of a fermion. Being just a kind of zero-approximation to a theory of particles and interactions below the quark scale, our model however predicts masses of fermions with an accuracy of about 0.0002% without using any experimental input parameters.
Quantum treatment of two-stage sub-Doppler laser cooling of magnesium atoms
Brazhnikov, D V; Taichenachev, A V; Yudin, V I; Bonert, A E; Il'enkov, R Ya; Goncharov, A N
2015-01-01
The problem of deep laser cooling of $^{24}$Mg atoms is theoretically studied. We propose two-stage sub-Doppler cooling strategy using electro-dipole transition $3^3P_2$$\\to$$3^3D_3$ ($\\lambda$=383.9 nm). The first stage implies exploiting magneto-optical trap with $\\sigma^+$ and $\\sigma^-$ light beams, while the second one uses a lin$\\perp$lin molasses. We focus on achieving large number of ultracold atoms (T$_{eff}$ < 10 $\\mu$K) in a cold atomic cloud. The calculations have been done out of many widely used approximations and based on quantum treatment with taking full account of recoil effect. Steady-state average kinetic energies and linear momentum distributions of cold atoms are analysed for various light-field intensities and frequency detunings. The results of conducted quantum analysis have revealed noticeable differences from results of semiclassical approach based on the Fokker-Planck equation. At certain conditions the second cooling stage can provide sufficiently lower kinetic energies of atom...
Fenker, Benjamin; Melconian, Dan; Anderson, Rhys M A; Anholm, Melissa; Ashery, Daniel; Behling, Richard S; Cohen, Iuliana; Craiciu, Ioana; Donohue, John M; Farfan, Christian; Friesen, Daniel; Gorelov, Alexandre; McNeil, James; Mehlman, Michael; Norton, Heather; Olchanski, Konstantin; Smale, Scott; Theriault, O; Vantyghem, Adrian N; Warner, Claire L
2016-01-01
We report a measurement of the nuclear polarization of laser-cooled, optically-pumped $^{37}\\mathrm{K}$ atoms which will allow us to precisely measure angular correlation parameters in the beta-decay of the same atoms. These results will be used to test the $V-A$ framework of the weak interaction at high precision. At the TRIUMF Neutral Atom Trap (TRINAT), a magneto-optical trap (MOT) confines and cools neutral $^{37}\\mathrm{K}$ atoms and optical pumping spin-polarizes them. We monitor the nuclear polarization of the same atoms that are decaying in situ by photoionizing a small fraction of the partially polarized atoms and then use the standard optical Bloch equations to model their population distribution. We obtain an average nuclear polarization of $P = 0.9913\\pm0.0008$, which is significantly more precise than previous measurements with this technique. Since our current measurement of the beta-asymmetry has $0.2\\%$ statistical uncertainty, the polarization measurement reported here will not limit its over...
Performance predictions of a focused ion beam from a laser cooled and compressed atomic beam
Energy Technology Data Exchange (ETDEWEB)
Haaf, G. ten; Wouters, S. H. W.; Vredenbregt, E. J. D.; Mutsaers, P. H. A. [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Geer, S. B. van der [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Pulsar Physics, Burghstraat 47, 5614 BC Eindhoven (Netherlands)
2014-12-28
Focused ion beams are indispensable tools in the semiconductor industry because of their ability to image and modify structures at the nanometer length scale. Here, we report on performance predictions of a new type of focused ion beam based on photo-ionization of a laser cooled and compressed atomic beam. Particle tracing simulations are performed to investigate the effects of disorder-induced heating after ionization in a large electric field. They lead to a constraint on this electric field strength which is used as input for an analytical model which predicts the minimum attainable spot size as a function of, amongst others, the flux density of the atomic beam, the temperature of this beam, and the total current. At low currents (I < 10 pA), the spot size will be limited by a combination of spherical aberration and brightness, while at higher currents, this is a combination of chromatic aberration and brightness. It is expected that a nanometer size spot is possible at a current of 1 pA. The analytical model was verified with particle tracing simulations of a complete focused ion beam setup. A genetic algorithm was used to find the optimum acceleration electric field as a function of the current. At low currents, the result agrees well with the analytical model, while at higher currents, the spot sizes found are even lower due to effects that are not taken into account in the analytical model.
Performance predictions of a focused ion beam based on laser cooling
Haaf, G ten; van der Geer, S B; Vredenbregt, E J D; Mutsaers, P H A
2014-01-01
Focused ion beams are indispensable tools in the semiconductor industry because of their ability to image and modify structures at the nanometer length scale. Here we report on performance predictions of a new type of focused ion beam based on photo-ionization of a laser cooled and compressed atomic beam. Particle tracing simulations are performed to investigate the effects of disorder-induced heating after ionization in a large electric field. They lead to a constraint on this electric field strength which is used as input for an analytical model which predicts the minimum attainable spot size as a function of amongst others the flux density of the atomic beam, the temperature of this beam and the total current. At low currents (I<10 pA) the spot size will be limited by a combination of spherical aberration and brightness, while at higher currents this is a combination of chromatic aberration and brightness. It is expected that a nanometer size spot is possible at a current of 1 pA. The analytical model w...
New approaches in deep laser cooling of magnesium atoms for quantum metrology
Prudnikov, O. N.; Brazhnikov, D. V.; Taichenachev, A. V.; Yudin, V. I.; Bonert, A. E.; Tropnikov, M. A.; Goncharov, A. N.
2016-09-01
Two approaches for solving the long-standing problem of deep laser cooling of neutral magnesium atoms are proposed. The first one uses optical molasses with orthogonal linear polarizations of light waves. The second approach involves a ‘nonstandard’ magneto-optical trap (NMOT) composed of light waves with elliptical polarizations (in general). Both the widely used semiclassical approach based on the Fokker-Planck equation and quantum treatment fully taking into account the recoil effect are employed for theoretical analysis. The results show the possibility of obtaining temperatures lower than 100 µK simultaneously with a large number of cold atoms ~106 ÷ 107. A new velocity-selective cooling technique allowing one to reach the microkelvin temperature range is also proposed. This technique may have some advantages over, for instance, the shallow-dipole-trap technique utilized by other authors. In the case of magnesium atoms this new technique may be used for obtaining a large number of ultracold atoms (T ~ 1 µK, N > 105). Such a large number of ultracold atoms is crucial issue for metrological and many other applications of cold atoms.
An ytterbium quantum gas microscope with narrow-line laser cooling
Yamamoto, Ryuta; Kobayashi, Jun; Kato, Kohei; Kuno, Takuma; Sakura, Yuto; Takahashi, Yoshiro
2016-05-01
Single-site resolved imaging of alkali metal in a two-dimensional optical lattice (Quantum Gas Microscope, QGM) is realized and enables us to directly observe the in-trap atom distribution and study quantum dynamics with single-site resolution. It is important to extend the applicability of a QGM technique to two-electron atoms such as alkaline-earth metal and ytterbium (Yb) atoms because it opens up many unique possibilities for the quantum simulation and quantum information research. Differently from the first report on single-site resolved imaging of Yb atoms with a long lattice constant 544 nm and a short lifetime of 62 μs without cooling, we successfully realize the QGM of Yb atoms with a short lattice constant 266 nm, in which we achieve a high-resolution imaging with a low temperature of 7.4 μK and a long lifetime of 7 s by narrow-line laser cooling. The high detection fidelity of 87(2) % is achieved in our method. In addition, we are developing a different mode of QGM for Yb atoms.
Interaction of laser-cooled $^{87}$Rb atoms with higher order modes of an optical nanofiber
Kumar, Ravi; Maimaiti, Aili; Deasy, Kieran; Frawley, Mary C; Chormaic, Síle Nic
2013-01-01
Optical nanofibers can be used to confine light to submicron regions and are very promising for the realization of optical fiber-based quantum networks using cold, neutral atoms. Light propagating in the higher order modes of a nanofiber has a greater evanescent field extension around the waist in comparison with the fundamental mode, leading to a stronger interaction with the surrounding environment. In this work, we report on the integration of a few-mode, optical nanofiber, with a waist diameter of ~700 nm, into a magneto-optical trap for $^{87}$Rb atoms. The nanofiber is fabricated from 80 $\\mu$m diameter fiber using a brushed hydrogen-oxygen flame pulling rig. We show that absorption by laser-cooled atoms around the waist of the nanofiber is stronger when probe light is guided in the higher order modes than in the fundamental mode. As predicted by Masalov and Minogin*, fluorescent light from the atoms coupling in to the nanofiber through the waist has a higher pumping rate (5.8 times) for the higher-orde...
Development of ytterbium-doped oxyfluoride glasses for laser cooling applications
Krishnaiah, Kummara Venkata; Soares de Lima Filho, Elton; Ledemi, Yannick; Nemova, Galina; Messaddeq, Younes; Kashyap, Raman
2016-01-01
Oxyfluoride glasses doped with 2, 5, 8, 12, 16 and 20 mol% of ytterbium (Yb3+) ions have been prepared by the conventional melt-quenching technique. Their optical, thermal and thermo-mechanical properties were characterized. Luminescence intensity at 1020 nm under laser excitation at 920 nm decreases with increasing Yb3+ concentration, suggesting a decrease in the photoluminescence quantum yield (PLQY). The PLQY of the samples was measured with an integrating sphere using an absolute method. The highest PLQY was found to be 0.99(11) for the 2 mol% Yb3+: glass and decreases with increasing Yb3+ concentration. The mean fluorescence wavelength and background absorption of the samples were also evaluated. Upconversion luminescence under 975 nm laser excitation was observed and attributed to the presence of Tm3+ and Er3+ ions which exist as impurity traces with YbF3 starting powder. Decay curves for the Yb3+: 2F5/2 → 2F7/2 transition exhibit single exponential behavior for all the samples, although lifetime decrease was observed for the excited level of Yb3+ with increasing Yb3+ concentration. Also observed are an increase in the PLQY and a slight decrease in lifetime with increasing the pump power. Finally, the potential of these oxyfluoride glasses with high PLQY and low background absorption for laser cooling applications is discussed. PMID:26915817
Forward to cryogenic temperature: laser cooling of Yb: LuLiF crystal
Zhong, Biao; Luo, Hao; Lei, Yongqing; Shi, Yanling; Yin, Jianping
2017-06-01
The high quality Yb-doped fluoride crystals have broad prospects for optical refrigeration. We have laser cooled the Yb:LuLiF crystal to a temperature below the limit of current thermoelectric coolers ( 180 K). The 5% Yb:LuLiF crystal sample has a geometry of 2 mm×2 mm×5 mm and was supported by two fibers of 200 μm in diameter. They were placed in a 2×10-4 Pa vacuum chamber with an environment temperature of 294.5 K. The 1019 nm CW laser of power 38.7 W was adopted to irradiate the sample. The temperature of the sample was measured utilizing the DLT methods. After 20 minutes of laser irradiation, the 5% Yb:LuLiF crystal sample was cooled down to 182.4 K. By further optimizing experimental conditions and increasing the doped Yb concentration, the Yb:LuLiF crystal might be optically cooled below the cryogenic temperature of 123K in the near future.
Interaction of laser-cooled 87Rb atoms with higher order modes of an optical nanofibre
Kumar, Ravi; Gokhroo, Vandna; Deasy, Kieran; Maimaiti, Aili; Frawley, Mary C.; Phelan, Ciarán; Chormaic, Síle Nic
2015-01-01
Optical nanofibres are used to confine light to sub-wavelength regions and are very promising tools for the development of optical fibre-based quantum networks using cold, neutral atoms. To date, experimental studies on atoms near nanofibres have focussed on fundamental fibre mode interactions. In this work, we demonstrate the integration of a few-mode optical nanofibre into a magneto-optical trap for 87Rb atoms. The nanofibre, with a waist diameter of ∼700 nm, supports both the fundamental and first group of higher order modes (HOMs) and is used for atomic fluorescence and absorption studies. In general, light propagating in higher order fibre modes has a greater evanescent field extension around the waist in comparison with the fundamental mode. By exploiting this behaviour, we demonstrate that the detected signal of fluorescent photons emitted from a cloud of cold atoms centred at the nanofibre waist is larger if HOMs are also included. In particular, the signal from HOMs appears to be about six times larger than that obtained for the fundamental mode. Absorption of on-resonance, HOM probe light by the laser-cooled atoms is also observed. These advances should facilitate the realization of atom trapping schemes based on HOM interference.
A cryogenic buffer gas cooled beam of BaH for molecular laser cooling and ultracold fragmentation
Iwata, Geoffrey; Tarallo, Marco G.; Soerensen, Fabian; Zelevinsky, Tanya
2015-05-01
Laser cooled and trapped molecules promise many possibilities to explore a variety of fields such as many-body physics, quantum collisions and dissociation, and precision measurement. We report on an experiment for cooling and trapping barium monohydride (BaH) diatomic molecules. We present a cryogenic buffer gas cooling apparatus for producing a 4 K beam of BaH, and describe the laser cooling schemes necessary to load a molecular magneto-optical trap from that beam. Current progress includes identification of the cooling transitions in the BaH B2 Σ molecules and construction of the molecular beam. The large mass ratio of constituent atoms in BaH makes this system attractive for future studies of ultracold fragmentation, potentially resulting in samples of ultracold hydrogen atoms.
Vetsch, E; Sagué, G; Schmidt, R; Dawkins, S T; Rauschenbeutel, A
2009-01-01
Trapping and optically interfacing laser-cooled neutral atoms is an essential requirement for their use in advanced quantum technologies. Here we simultaneously realize both of these tasks with cesium atoms interacting with a multi-color evanescent field surrounding an optical nanofiber. The atoms are localized in a one-dimensional optical lattice about 200 nm above the nanofiber surface and can be efficiently interrogated with a resonant light field sent through the nanofiber. Our technique opens the route towards the direct integration of laser-cooled atomic ensembles within fiber networks, an important prerequisite for large scale quantum communication schemes. Moreover, it is ideally suited to the realization of hybrid quantum systems that combine atoms with, e.g., solid state quantum devices.
Effects of spin-orbit coupling on laser cooling of BeI and MgI
Energy Technology Data Exchange (ETDEWEB)
Wan, Mingjie, E-mail: wanmingjie1983@sina.com; Huang, Duohui; Shao, Juxiang; Li, Yuanyuan [Computational Physics Key Laboratory of Sichuan Province, Yibin University, Yibin 644007 (China); Yu, You [College of Optoelectronic Technology, Chengdu University of Information Technology, Chengdu 610225 (China); Li, Song [College of Physical Science and Technology, Yangtze University, Jingzhou 434023 (China)
2015-10-28
We present the ab initio study of spin-orbit coupling effects on laser cooling of BeI and MgI molecules. Potential energy curves for the X{sup 2}Σ{sup +}{sub 1/2}, A{sup 2}Π{sub 1/2,3/2}, and 2{sup 2}Π{sub 3/2,1/2} states are calculated using multi-reference configuration interaction method plus Davidson corrections. Spectroscopic parameters of BeI and MgI are in excellent agreement with available experimental and theoretical values. The A{sup 2}Π{sub 3/2} state of MgI is a repulsive state. It is an unsuitable scheme for the A{sup 2}Π{sub 3/2}(υ′)← X{sup 2}Σ{sup +}{sub 1/2} (υ″) transition for laser cooling of MgI. Highly diagonally distributed Franck-Condon factors f{sub 00} for the A{sup 2}Π{sub 1/2,3/2} (υ′ = 0) ← X{sup 2}Σ{sup +}{sub 1/2} (υ″ = 0) transitions and suitable radiative lifetimes τ for the A{sup 2}Π{sub 1/2,3/2} (υ′ = 0) of BeI and MgI are obtained. Three laser wavelength drives are required for the A{sup 2}Π{sub 1/2,3/2}(υ′)←X{sup 2}Σ{sup +}{sub 1/2} (υ″) transitions of BeI and MgI. The proposed cooling wavelengths of BeI and MgI are both in the violet region. The results imply the feasibility of laser cooling of BeI and MgI, and that laser cooling of BeI is more possible.
Effects of spin-orbit coupling on laser cooling of BeI and MgI.
Wan, Mingjie; Huang, Duohui; Shao, Juxiang; Yu, You; Li, Song; Li, Yuanyuan
2015-10-28
We present the ab initio study of spin-orbit coupling effects on laser cooling of BeI and MgI molecules. Potential energy curves for the X(2)Σ(+)(1/2), A(2)Π(1/2,3/2), and 2(2)Π(3/2,1/2) states are calculated using multi-reference configuration interaction method plus Davidson corrections. Spectroscopic parameters of BeI and MgI are in excellent agreement with available experimental and theoretical values. The A(2)Π(3/2) state of MgI is a repulsive state. It is an unsuitable scheme for the A(2)Π(3/2)(υ')← X(2)Σ(+)(1/2) (υ″) transition for laser cooling of MgI. Highly diagonally distributed Franck-Condon factors f00 for the A(2)Π(1/2,3/2) (υ' = 0) ← X(2)Σ(+)(1/2) (υ″ = 0) transitions and suitable radiative lifetimes τ for the A(2)Π(1/2,3/2) (υ' = 0) of BeI and MgI are obtained. Three laser wavelength drives are required for the A(2)Π(1/2,3/2)(υ')←X(2)Σ(+)(1/2) (υ″) transitions of BeI and MgI. The proposed cooling wavelengths of BeI and MgI are both in the violet region. The results imply the feasibility of laser cooling of BeI and MgI, and that laser cooling of BeI is more possible.
Truppe, Stefan; Holland, Darren; Hendricks, Richard James; Hinds, Ed; Tarbutt, Michael
2014-06-01
We aim to slow a supersonic, molecular beam of 11BH using a Zeeman slower and subsequently cool the molecules to sub-millikelvin temperatures in a magneto-optical trap. Most molecules are not suitable for direct laser cooling because the presence of rotational and vibrational degrees of freedom means there is no closed-cycle transition which is necessary to scatter a large number of photons. As was pointed out by Di Rosa, there exists a class of molecules for which the excitation of vibrational modes is suppressed due to highly diagonal Franck-Condon factors. Furthermore, Stuhl et al. showed that angular momentum selection rules can be used to suppress leakage to undesired rotational states. Here we present a measurement of the radiative branching ratios of the A^1Π→ X^1Σ transition in 11BH - a necessary step towards subsequent laser cooling experiments. We also perform high-resolution mm-wave spectroscopy of the J'=1← J=0 rotational transition in the X^1Σ (v=0) state near 708 GHz. From this measurement we derive new, accurate hyper fine constants and compare these to theoretical descriptions. The measured branching ratios suggest that it is possible to laser cool 11BH molecules close to the recoil temperature of 4 μK using three laser frequencies only. M. D. Di Rosa, The European Physical Journal D, 31, 395, 2004 B. K. Stuhl et al., Physical Review Letters, 101, 243002, 2008
Fermion dispersion in axion medium
Mikheev, N. V.; Narynskaya, E. N.
2008-01-01
The interaction of a fermion with the dense axion medium is investigated for the purpose of finding an axion medium effect on the fermion dispersion. It is shown that axion medium influence on the fermion dispersion under astrophysical conditions is negligible small if the correct Lagrangian of the axion-fermion interaction is used.
Fermions as Topological Objects
Directory of Open Access Journals (Sweden)
Yershov V. N.
2006-01-01
Full Text Available A preon-based composite model of the fundamental fermions is discussed, in which the fermions are bound states of smaller entities — primitive charges (preons. The preon is regarded as a dislocation in a dual 3-dimensional manifold — a topological object with no properties, save its unit mass and unit charge. It is shown that the dualism of this manifold gives rise to a hierarchy of complex structures resembling by their properties three families of the fundamental fermions. Although just a scheme for building a model of elementary particles, this description yields a quantitative explanation of many observable particle properties, including their masses.
Complex fermion coherent states
Tyc, T; Sanders, B C; Oliver, W D; Tyc, Tomas; Hamilton, Brett; Sanders, Barry C.; Oliver, William D.
2005-01-01
Whereas boson coherent states provide an elegant, intuitive and useful representation, we show that the desirable features of boson coherent states do not carry over very well to fermion fields unless one is prepared to use exotic approaches such as Grassmann fields. Specifically, we identify four appealing properties of boson coherent states (eigenstate of annihilation operator, displaced vacuum state, preservation of product states under linear coupling, and factorization of correlators) and show that fermion coherent states, and approximations to fermion coherent states, defined over the complex field, do not behave well for any of these four criteria.
Semiclassical Theory of Fermions
Florentino Ribeiro, Raphael
2016-01-01
A blend of non-perturbative semiclassical techniques is employed to systematically construct approximations to noninteracting many-fermion systems (coupled to some external potential mimicking the Kohn-Sham potential of density functional theory). In particular, uniform asymptotic approximations are obtained for the particle and kinetic energy density in terms of the external potential acting on the fermions and the Fermi energy. Dominant corrections to the classical limit of quantum mechanic...
Zhang, Qing-Qing; Yang, Chuan-Lu; Wang, Mei-Shan; Ma, Xiao-Guang; Liu, Wen-Wang
2017-10-01
The potential energy curves and transition dipole moments of 12Σ+, 22Σ+, 12Π and 22Π states of NH+ cation and NH- anion are calculated by using multi-reference configuration interaction method and large all-electron basis sets. Based on the obtained potential energy curves, the rotational and vibrational energy levels of the states are obtained by solving the Schrödinger equation of nuclear movement. The calculated spectroscopic parameters for NH+ cation and NH- anion are in good agreement with available theoretical and experimental results. The spin orbit coupling effect of the 2Π states for both NH+ cation and NH- anion are calculated. The feasibility of laser cooling of the two molecules is examined by using the results of the molecular structure and spectroscopy. The highly diagonal Franck-Condon factors for the 12Π (v″ = 0) ↔ 12Σ+ (v‧ = 0) transition of NH+ and NH- are 0.821 and 0.999, while the radiative lifetimes of the 12Σ+ (v‧ = 0) state for the two molecules are 384 ns and 52.4 ns, respectively. The results indicate that NH+ cation and NH- anion are good candidate molecules for laser cooling. The cooling scheme via Sisyphus process for the NH+ cation and NH- anion are proposed in the paper. The laser wavelengths for the close cycles of the absorption and radiation are also determined. Unfortunately, the potential energy curve of the ground state of the neutral NH molecule shows that the auto-detachment of NH- anion is possible, implying the optical scheme of laser cooling for NH- anion is not easy to achieve in the experiment although it has larger Franck-Condon factor.
Zhang, Qing-Qing; Yang, Chuan-Lu; Wang, Mei-Shan; Ma, Xiao-Guang; Liu, Wen-Wang
2017-10-05
The potential energy curves and transition dipole moments of 1(2)Σ(+), 2(2)Σ(+), 1(2)Π and 2(2)Π states of NH(+) cation and NH(-) anion are calculated by using multi-reference configuration interaction method and large all-electron basis sets. Based on the obtained potential energy curves, the rotational and vibrational energy levels of the states are obtained by solving the Schrödinger equation of nuclear movement. The calculated spectroscopic parameters for NH(+) cation and NH(-) anion are in good agreement with available theoretical and experimental results. The spin orbit coupling effect of the (2)Π states for both NH(+) cation and NH(-) anion are calculated. The feasibility of laser cooling of the two molecules is examined by using the results of the molecular structure and spectroscopy. The highly diagonal Franck-Condon factors for the 1(2)Π (v″=0)↔1(2)Σ(+) (v'=0) transition of NH(+) and NH(-) are 0.821 and 0.999, while the radiative lifetimes of the 1(2)Σ(+) (v'=0) state for the two molecules are 384ns and 52.4ns, respectively. The results indicate that NH(+) cation and NH(-) anion are good candidate molecules for laser cooling. The cooling scheme via Sisyphus process for the NH(+) cation and NH(-) anion are proposed in the paper. The laser wavelengths for the close cycles of the absorption and radiation are also determined. Unfortunately, the potential energy curve of the ground state of the neutral NH molecule shows that the auto-detachment of NH(-) anion is possible, implying the optical scheme of laser cooling for NH(-) anion is not easy to achieve in the experiment although it has larger Franck-Condon factor. Copyright © 2017 Elsevier B.V. All rights reserved.
Shimada, Yosuke; Ohtsubo, Nozomi; Aoki, Takatoshi; Torii, Yoshio
2013-01-01
We develop a simplified light source at 461 nm for laser cooling of Sr without frequency-doubling crystals but with blue laser diodes. An anti-reflection coated blue laser diode in an external cavity (Littrow) configuration provides an output power of 40 mW at 461 nm. Another blue laser diode is used to amplify the laser power up to 110 mW by injection locking. For frequency stabilization, we demonstrate modulation-free polarization spectroscopy of Sr in a hollow cathode lamp. The simplification of the laser system achieved in this work is of great importance for the construction of transportable optical lattice clocks.
Shimada, Yosuke; Chida, Yuko; Ohtsubo, Nozomi; Aoki, Takatoshi; Takeuchi, Makoto; Kuga, Takahiro; Torii, Yoshio
2013-06-01
We develop a simplified light source at 461 nm for laser cooling of Sr without frequency-doubling crystals but with blue laser diodes. An anti-reflection coated blue laser diode in an external cavity (Littrow) configuration provides an output power of 40 mW at 461 nm. Another blue laser diode is used to amplify the laser power up to 110 mW by injection locking. For frequency stabilization, we demonstrate modulation-free polarization spectroscopy of Sr in a hollow cathode lamp. The simplification of the laser system achieved in this work is of great importance for the construction of transportable optical lattice clocks.
Fu, Mingkai; Ma, Haitao; Cao, Jianwei; Bian, Wensheng
2016-05-01
Nine doublet Λ-S states of calcium monochloride (CaCl) are calculated using the internally contracted multireference configuration interaction method with the Davidson correction. Both the core subvalence and spin-orbit coupling effects are taken into account. Laser cooling of CaCl and production of ultracold chlorine atoms are investigated and assessed. Our computed spectroscopic constants and radiative lifetimes match the available experimental data very well. The determined Franck-Condon factors and vibrational branching ratios of the A 2 Π 1 / 2 ( ν ' ) ← X 2 Σ1 / 2 + ( ν ) transition are highly diagonally distributed and the evaluated radiative lifetime for the A2Π1/2(ν' = 0) state is 28.2 ns, which is short enough for rapid laser cooling. Subsequently, detection of cold molecules via resonance enhanced multiphoton ionization to determine the final quantum state populations is discussed and the ionization energy calculated. A multi-pulse excitation scheme is proposed for producing ultracold chlorine atoms from zero-energy photodissociation of the cooled CaCl. Our results demonstrate the possibility of producing ultracold CaCl molecules and Cl atoms.
Dai, D P; Xia, Y; Yin, Y N; Yang, X X; Fang, Y F; Li, X J; Yin, J P
2014-11-17
We demonstrate a robust and versatile solution for locking the continuous-wave dye laser for applications in laser cooling of molecules which need linewidth-narrowed and frequency-stabilized lasers. The dye laser is first stabilized with respect to a reference cavity by Pound-Drever-Hall (PDH) technique which results in a single frequency with the linewidth 200 kHz and short-term stabilization, by stabilizing the length of the reference cavity to a stabilized helium-neon laser we simultaneously transfer the ± 2 MHz absolute frequency stability of the helium-neon laser to the dye laser with long-term stabilization. This allows the dye laser to be frequency chirped with the maximum 60 GHz scan range while its frequency remains locked. It also offers the advantages of locking at arbitrary dye laser frequencies, having a larger locking capture range and frequency scanning range to be implemented via software. This laser has been developed for the purpose of laser cooling a molecular magnesium fluoride beam.
Zhang, Qing-Qing; Yang, Chuan-Lu; Wang, Mei-Shan; Ma, Xiao-Guang; Liu, Wen-Wang
2017-07-05
The potential energy curves and transition dipole moments for the 1(2)Σ(+), 2(2)Σ(+), 1(2)Π and 2(2)Π electronic states of the two molecules are calculated using multi-reference configuration interaction and the large basis sets aug-cc-pwCV5Z. Based on the obtained potential energy curves, the rotational and vibrational energy levels of the states are obtained by solving the Schrödinger equation of nuclear motion, and the spectroscopic parameters are then obtained by fitting the energy levels to Dunham series expansions. The spin-orbit coupling effect of the (2)Π states for both the BH(+) cation and BH(-) anion are calculated. Highly diagonally distributed Franck-Condon factors are determined for the 1(2)Σ(+) (v″=0)↔1(2)Π (v'=0) transition, ƒ00 (BH(+))=0.943, while the Franck-Condon factors for the 1(2)Π (v″=0)↔1(2)Σ(+) (v'=0) transition is ƒ00 (BH(-))=0.942. Moreover, the radiative lifetime of 38.2ns for the excited 1(2)Π state of the BH(+) and 91.8ns for the 1(2)Σ(+) state of the BH(-) are obtained, which are short enough for rapid laser cooling. A three-step optical scheme of the laser cooling is constructed for either the BH(+) cation or the BH(-) anion. Copyright © 2017 Elsevier B.V. All rights reserved.
The low-lying electronic states and optical schemes for the laser cooling of the BH+ and BH- ions
Zhang, Qing-Qing; Yang, Chuan-Lu; Wang, Mei-Shan; Ma, Xiao-Guang; Liu, Wen-Wang
2017-07-01
The potential energy curves and transition dipole moments for the 12Σ+, 22Σ+, 12Π and 22Π electronic states of the two molecules are calculated using multi-reference configuration interaction and the large basis sets aug-cc-pwCV5Z. Based on the obtained potential energy curves, the rotational and vibrational energy levels of the states are obtained by solving the Schrödinger equation of nuclear motion, and the spectroscopic parameters are then obtained by fitting the energy levels to Dunham series expansions. The spin-orbit coupling effect of the 2Π states for both the BH+ cation and BH- anion are calculated. Highly diagonally distributed Franck-Condon factors are determined for the 12Σ+ (v″ = 0) ↔ 12Π (v‧ = 0) transition, ƒ00 (BH+) = 0.943, while the Franck-Condon factors for the 12Π (v″ = 0) ↔ 12Σ+ (v‧ = 0) transition is ƒ00 (BH-) = 0.942. Moreover, the radiative lifetime of 38.2 ns for the excited 12Π state of the BH+ and 91.8 ns for the 12Σ+ state of the BH- are obtained, which are short enough for rapid laser cooling. A three-step optical scheme of the laser cooling is constructed for either the BH+ cation or the BH- anion.
Interacting composite fermions
DEFF Research Database (Denmark)
nrc762, nrc762
2016-01-01
dominates. The interaction between composite fermions in the second Λ level (composite fermion analog of the electronic Landau level) satisfies this property, and recent studies have supported unconventional fractional quantum Hall effect of composite fermions at ν∗=4/3 and 5/3, which manifests...... as fractional quantum Hall effect of electrons at ν=4/11, 4/13, 5/13, and 5/17. I investigate in this article the nature of the fractional quantum Hall states at ν=4/5, 5/7, 6/17, and 6/7, which correspond to composite fermions at ν∗=4/3, 5/3, and 6/5, and find that all these fractional quantum Hall states...... are conventional. The underlying reason is that the interaction between composite fermions depends substantially on both the number and the direction of the vortices attached to the electrons. I also study in detail the states with different spin polarizations at 6/17 and 6/7 and predict the critical Zeeman...
Fermion masses from dimensional reduction
Energy Technology Data Exchange (ETDEWEB)
Kapetanakis, D. (National Research Centre for the Physical Sciences Democritos, Athens (Greece)); Zoupanos, G. (European Organization for Nuclear Research, Geneva (Switzerland))
1990-10-11
We consider the fermion masses in gauge theories obtained from ten dimensions through dimensional reduction on coset spaces. We calculate the general fermion mass matrix and we apply the mass formula in illustrative examples. (orig.).
Kamleh, W; Williams, A G; Kamleh, Waseem; Leinweber, Derek B.; Williams, Anthony G.; 10.1016/j.nuclphysbps.2003.12.058
2004-01-01
The use of APE smearing or other blocking techniques in fermion actions can provide many advantages. There are many variants of these fat link actions in lattice QCD currently, such as FLIC fermions. Frequently, fat link actions make use of the APE blocking technique in combination with a projection of the blocked links back into the special unitary group. This reunitarisation is often performed using an iterative maximisation of a gauge invariant measure. This technique is not differentiable with respect to the gauge field and thus prevents the use of standard Hybrid Monte Carlo simulation algorithms. The use of an alternative projection technique circumvents this difficulty and allows the simulation of dynamical fat link fermions with standard HMC and its variants.
Cold asymmetrical fermion superfluids
Energy Technology Data Exchange (ETDEWEB)
Caldas, Heron
2003-12-19
The recent experimental advances in cold atomic traps have induced a great amount of interest in fields from condensed matter to particle physics, including approaches and prospects from the theoretical point of view. In this work we investigate the general properties and the ground state of an asymmetrical dilute gas of cold fermionic atoms, formed by two particle species having different densities. We have show in a recent paper, that a mixed phase composed of normal and superfluid components is the energetically favored ground state of such a cold fermionic system. Here we extend the analysis and verify that in fact, the mixed phase is the preferred ground state of an asymmetrical superfluid in various situations. We predict that the mixed phase can serve as a way of detecting superfluidity and estimating the magnitude of the gap parameter in asymmetrical fermionic systems.
Tsekov, R
2016-01-01
Thermodynamically, bosons and fermions differ by their statistics only. A general entropy functional is proposed by superposition of entropic terms, typical for different quantum gases. The statistical properties of the corresponding Janus particles are derived by variation of the weight of the boson/fermion fraction. It is shown that di-bosons and anti-fermions separate in gas and liquid phases, while three-phase equilibrium appears for poly-boson/fermion Janus particles.
Grand Unification and Exotic Fermions
Feger, Robert P
2015-01-01
We exploit the recently developed software package LieART to show that SU(N) grand unified theories with chiral fermions in mixed tensor irreducible representations can lead to standard model chiral fermions without additional light exotic chiral fermions, i.e., only standard model fermions are light in these models. Results are tabulated which may be of use to model builders in the future. An SU(6) toy model is given and model searches are discussed.
Unification with mirror fermions
Directory of Open Access Journals (Sweden)
Triantaphyllou George
2014-04-01
Full Text Available We present a new framework unifying interactions in nature by introducing mirror fermions, explaining the hierarchy between the weak scale and the coupling unification scale, which is found to lie close to Planck energies. A novel process leading to the emergence of symmetry is proposed, which not only reduces the arbitrariness of the scenario proposed but is also followed by significant cosmological implications. Phenomenology includes the probability of detection of mirror fermions via the corresponding composite bosonic states and the relevant quantum corrections at the LHC.
Fermions from classical statistics
2010-01-01
We describe fermions in terms of a classical statistical ensemble. The states $\\tau$ of this ensemble are characterized by a sequence of values one or zero or a corresponding set of two-level observables. Every classical probability distribution can be associated to a quantum state for fermions. If the time evolution of the classical probabilities $p_\\tau$ amounts to a rotation of the wave function $q_\\tau(t)=\\pm \\sqrt{p_\\tau(t)}$, we infer the unitary time evolution of a quantum system of fe...
Bipartite Composite Fermion States
Sreejith, G. J.; Tőke, C.; Wójs, A.; Jain, J. K.
2011-08-01
We study a class of ansatz wave functions in which composite fermions form two correlated “partitions.” These “bipartite” composite fermion states are demonstrated to be very accurate for electrons in a strong magnetic field interacting via a short-range 3-body interaction potential over a broad range of filling factors. Furthermore, this approach gives accurate approximations for the exact Coulomb ground state at 2+3/5 and 2+4/7 and is thus a promising candidate for the observed fractional quantum Hall states at the hole conjugate fractions at 2+2/5 and 2+3/7.
Chiral fermions on the lattice
Jahn, O; Jahn, Oliver; Pawlowski, Jan M.
2002-01-01
We discuss topological obstructions to putting chiral fermions on an even dimensional lattice. The setting includes Ginsparg-Wilson fermions, but is more general. We prove a theorem which relates the total chirality to the difference of generalised winding numbers of chiral projection operators. For an odd number of Weyl fermions this implies that particles and anti-particles live in topologically different spaces.
Topological susceptibility from overlap fermion
Institute of Scientific and Technical Information of China (English)
应和平; 张剑波
2003-01-01
We numerically calculate the topological charge of the gauge configurations on a finite lattice by the fermionic method with overlap fermions. By using the lattice index theorem, we identify the index of the massless overlap fermion operator to the topological charge of the background gauge configuration. The resulting topological susceptibility X is in good agreement with the anticipation made by Witten and Veneziano.
Combescure, Monique; Robert, Didier
2012-06-01
The aim of this paper is to give a self-contained and unified presentation of a fermionic coherent state theory with the necessary mathematical details, discussing their definition, properties and some applications. After defining Grassmann algebras, it is possible to get a classical analog for the fermionic degrees of freedom in a quantum system. Following the basic work of Berezin (1966 The Method of Second Quantization (New York: Academic); 1987 Introduction to Superanalysis (Dordrecht: Reidel Publishing Company)), we show that we can compute with Grassmann numbers as we do with complex numbers: derivation, integration, Fourier transform. After that we show that we have quantization formulas for fermionic observables. In particular, there exists a Moyal product formula. As an application, we consider explicit computations for propagators with quadratic Hamiltonians in annihilation and creation operators. We prove a Mehler formula for the propagator and Mehlig-Wilkinson-type formulas for the covariant and contravariant symbols of ‘metaplectic’ transformations for fermionic states. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Coherent states: mathematical and physical aspects’.
Phantom cosmologies and fermions
Chimento, Luis P; Forte, Monica; Kremer, Gilberto M
2007-01-01
Form invariance transformations can be used for constructing phantom cosmologies starting with conventional cosmological models. In this work we reconsider the scalar field case and extend the discussion to fermionic fields, where the "phantomization" process exhibits a new class of possible accelerated regimes.
Cabra, D C; Cabra, Daniel C; Rossini, Gerardo L
1996-01-01
We give an explicit holomorphic factorization of SU(N)_1 WZW primaries in terms of gauge invariant composite fermions. In the N=2 case, we show that these composites realize the spinon algebra. Both in this and in the general case, the underlying Yangian symmetry implies that these operators span the whole Fock space.
Fermions, wigs, and attractors
Energy Technology Data Exchange (ETDEWEB)
Gentile, L.G.C., E-mail: lgentile@pd.infn.it [DISIT, Università del Piemonte Orientale, via T. Michel, 11, Alessandria 15120 (Italy); Dipartimento di Fisica “Galileo Galilei”, Università di Padova, via Marzolo 8, 35131 Padova (Italy); INFN, Sezione di Padova, via Marzolo 8, 35131 Padova (Italy); Grassi, P.A., E-mail: pgrassi@mfn.unipmn.it [DISIT, Università del Piemonte Orientale, via T. Michel, 11, Alessandria 15120 (Italy); INFN, Gruppo Collegato di Alessandria, Sezione di Torino (Italy); Marrani, A., E-mail: alessio.marrani@fys.kuleuven.be [ITF KU Leuven, Celestijnenlaan 200D, 3001 Leuven (Belgium); Mezzalira, A., E-mail: andrea.mezzalira@ulb.ac.be [Physique Théorique et Mathématique Université Libre de Bruxelles, C.P. 231, 1050 Bruxelles (Belgium)
2014-05-01
We compute the modifications to the attractor mechanism due to fermionic corrections. In N=2,D=4 supergravity, at the fourth order, we find terms giving rise to new contributions to the horizon values of the scalar fields of the vector multiplets.
Renormalization of fermion mixing
Energy Technology Data Exchange (ETDEWEB)
Schiopu, R.
2007-05-11
Precision measurements of phenomena related to fermion mixing require the inclusion of higher order corrections in the calculation of corresponding theoretical predictions. For this, a complete renormalization scheme for models that allow for fermion mixing is highly required. The correct treatment of unstable particles makes this task difficult and yet, no satisfactory and general solution can be found in the literature. In the present work, we study the renormalization of the fermion Lagrange density with Dirac and Majorana particles in models that involve mixing. The first part of the thesis provides a general renormalization prescription for the Lagrangian, while the second one is an application to specific models. In a general framework, using the on-shell renormalization scheme, we identify the physical mass and the decay width of a fermion from its full propagator. The so-called wave function renormalization constants are determined such that the subtracted propagator is diagonal on-shell. As a consequence of absorptive parts in the self-energy, the constants that are supposed to renormalize the incoming fermion and the outgoing antifermion are different from the ones that should renormalize the outgoing fermion and the incoming antifermion and not related by hermiticity, as desired. Instead of defining field renormalization constants identical to the wave function renormalization ones, we differentiate the two by a set of finite constants. Using the additional freedom offered by this finite difference, we investigate the possibility of defining field renormalization constants related by hermiticity. We show that for Dirac fermions, unless the model has very special features, the hermiticity condition leads to ill-defined matrix elements due to self-energy corrections of external legs. In the case of Majorana fermions, the constraints for the model are less restrictive. Here one might have a better chance to define field renormalization constants related by
Al-Hashimi, M H; Wiese, U -J
2016-01-01
Majorana fermion dynamics may arise at the edge of Kitaev wires or superconductors. Alternatively, it can be engineered by using trapped ions or ultracold atoms in an optical lattice as quantum simulators. This motivates the theoretical study of Majorana fermions confined to a finite volume, whose boundary conditions are characterized by self-adjoint extension parameters. While the boundary conditions for Dirac fermions in $(1+1)$-d are characterized by a 1-parameter family, $\\lambda = - \\lambda^*$, of self-adjoint extensions, for Majorana fermions $\\lambda$ is restricted to $\\pm i$. Based on this result, we compute the frequency spectrum of Majorana fermions confined to a 1-d interval. The boundary conditions for Dirac fermions confined to a 3-d region of space are characterized by a 4-parameter family of self-adjoint extensions, which is reduced to two distinct 1-parameter families for Majorana fermions. We also consider the problems related to the quantum mechanical interpretation of the Majorana equation ...
Indian Academy of Sciences (India)
S Pradhan; S Mishra; R Behera; N Kawade; A K Das
2014-02-01
We have investigated coherent population trapping (CPT) in laser-cooled as well as room-temperature (with and without buffer gas) rubidium atoms. The characteristic broad signal profile emerging from the two-photon Raman resonance for room-temperature atomic vapour is consistent with the theoretical calculation incorporating associated thermal averaging. The spectral width of the dark resonance obtained with cold atoms is found to be broadened, compared to roomtemperature vapour cell, due to the feeble role played by thermal averaging, although the cold atomic sample significantly overcomes the limitation of the transit time broadening. An alternative way to improve transit time is to use a buffer gas, with which we demonstrate that the coherent population trapping signal width is reduced to < 540 Hz.
Fermionic T-duality in fermionic double space
Nikolic, Bojan
2016-01-01
In this article we offer the interpretation of the fermionic T-duality of the type II superstring theory in double space. We generalize the idea of double space doubling the fermionic sector of the superspace. In such doubled space fermionic T-duality is repersented as permutation of the fermionic coordinates $\\theta^\\alpha$ and $\\bar\\theta^\\alpha$ with the corresponding fermionic T-dual ones, $\\vartheta_\\alpha$ and $\\bar\\vartheta_\\alpha$, respectively. Demanding that T-dual transformation law has the same form as inital one, we obtain the known form of the fermionic T-dual NS-R i R-R background fields. Fermionic T-dual NS-NS background fields are obtained under some assumptions. We conclude that only symmetric part of R-R field strength and symmetric part of its fermionic T-dual contribute to the fermionic T-duality transformation of dilaton field and analyze the dilaton field in fermionic double space. As a model we use the ghost free action of type II superstring in pure spinor formulation in approximation...
Fermionic T-duality in fermionic double space
Nikolić, B.; Sazdović, B.
2017-04-01
In this article we offer the interpretation of the fermionic T-duality of the type II superstring theory in double space. We generalize the idea of double space doubling the fermionic sector of the superspace. In such doubled space fermionic T-duality is represented as permutation of the fermionic coordinates θα and θbarα with the corresponding fermionic T-dual ones, ϑα and ϑbarα, respectively. Demanding that T-dual transformation law has the same form as initial one, we obtain the known form of the fermionic T-dual NS-R and R-R background fields. Fermionic T-dual NS-NS background fields are obtained under some assumptions. We conclude that only symmetric part of R-R field strength and symmetric part of its fermionic T-dual contribute to the fermionic T-duality transformation of dilaton field and analyze the dilaton field in fermionic double space. As a model we use the ghost free action of type II superstring in pure spinor formulation in approximation of constant background fields up to the quadratic terms.
Anomalous saturated absorption providing a stable laser lock for $^{171}$Yb laser cooling
McFerran, J J
2016-01-01
We identify an inverted Lamb dip in the saturated absorption spectroscopy of the $(6s^{2})$ $^{1}S_{0}$ $-$ $(6s6p)$ $^{3}P_{1}$ transition in $^{171}$Yb. The signal has only been observed with the two hyperfine lines of this spin $I=\\frac{1}{2}$ isotope. For both lines the application of a dc magnetic field transforms a two-level scheme into a four-level scheme, with degeneracy only marginally lifted in the ground state. The atoms are excited through $\\pi$ transitions, while the de-excitation process completes a simple optical pumping scheme. However, the full explanation of the enhanced absorption is yet to be determined. The anomalous absorption signal is used to generate a dispersive curve for 556 nm laser stabilisation and the stabilised light cools $^{171}$Yb atoms in a two-stage magneto-optical trap, achieving temperatures below 50 $\\mu$K. The Doppler-free spectroscopy scheme is further used to measure isotopic frequency shifts and hyperfine separations for the intercombination line in Yb.
Holomorphic Symplectic Fermions
Davydov, Alexei
2016-01-01
Let V be the even part of the vertex operator super-algebra of r pairs of symplectic fermions. Up to two conjectures, we show that V admits a unique holomorphic extension if r is a multiple of 8, and no holomorphic extension otherwise. This is implied by two results obtained in this paper: 1) If r is a multiple of 8, one possible holomorphic extension is given by the lattice vertex operator algebra for the even self dual lattice $D_r^+$ with shifted stress tensor. 2) We classify Lagrangian algebras in SF(h), a ribbon category associated to symplectic fermions. The classification of holomorphic extensions of V follows from 1) and 2) if one assumes that SF(h) is ribbon equivalent to Rep(V), and that simple modules of extensions of V are in one-to-one relation with simple local modules of the corresponding commutative algebra in SF(h).
Agrawal, Jyoti; Frampton, Paul H.; Jack Ng, Y.; Nishino, Hitoshi; Yasuda, Osamu
1991-03-01
An extension of the standard model is proposed. The gauge group is SU(2) X ⊗ SU(3) C ⊗ SU(2) S ⊗ U(1) Q, where all gauge symmetries are unbroken. The colour and electric charge are combined with SU(2) S which becomes strongly coupled at approximately 500 GeV and binds preons to form fermionic and vector bound states. The usual quarks and leptons are singlets under SU(2) X but additional fermions, called sarks. transform under it and the electroweak group. The present model explains why no more than three light quark-lepton families can exist. Neutral sark baryons, called narks, are candidates for the cosmological dark matter having the characteristics designed for WIMPS. Further phenomenological implications of sarks are analyzed i including electron-positron annihilation. Z 0 decay, flavor-changing neutral currents. baryon-number non-conservation, sarkonium and the neutron electric dipole moment.
Leptogenesis from split fermions
Energy Technology Data Exchange (ETDEWEB)
Nagatani, Yukinori; Perez, Gilad
2004-01-11
We present a new type of leptogenesis mechanism based on a two-scalar split-fermions framework. At high temperatures the bulk scalar vacuum expectation values (VEVs) vanish and lepton number is strongly violated. Below some temperature, T{sub c}, the scalars develop extra dimension dependent VEVs. This transition is assumed to proceed via a first order phase transition. In the broken phase the fermions are localized and lepton number violation is negligible. The lepton-bulk scalar Yukawa couplings contain sizable CP phases which induce lepton production near the interface between the two phases. We provide a qualitative estimation of the resultant baryon asymmetry which agrees with current observation. The neutrino flavor parameters are accounted for by the above model with an additional approximate U(1) symmetry.
Chavanis, Pierre-Henri; Méhats, Florian
2014-01-01
We study the fermionic King model which may provide a relevant model of dark matter halos. The exclusion constraint can be due to quantum mechanics (for fermions such as massive neutrinos) or to Lynden-Bell's statistics (for collisionless systems undergoing violent relaxation). This model has a finite mass. Furthermore, a statistical equilibrium state exists for all accessible values of energy. Dwarf and intermediate size halos are degenerate quantum objects stabilized against gravitational collapse by the Pauli exclusion principle. Large halos at sufficiently high energies are in a gaseous phase where quantum effects are negligible. They are stabilized by thermal motion. Below a critical energy they undergo gravitational collapse (gravothermal catastrophe). This may lead to the formation of a central black hole that does not affect the structure of the halo. This may also lead to the formation of a compact degenerate object surrounded by a hot massive atmosphere extending at large distances. We argue that la...
Lin, De-Hone
2015-01-01
This paper is concerned with the application of a spacetime structure to a three-dimensional quantum system. There are three components. First, the main part of this paper presents the constraint conditions which build the relation of a spacetime structure and a form invariance solution to the covariant Dirac equation. The second is to devise a spacetime cage for fermions with chosen constraints. The third part discusses the feasibility of the cage with an experiment.
Tripartite composite fermion states
Sreejith, G. J.; Wu, Ying-Hai; Wójs, A.; Jain, J. K.
2013-06-01
The Read-Rezayi wave function is one of the candidates for the fractional quantum Hall effect at filling fraction ν=2+⅗, and thereby also its hole conjugate at 2+⅖. We study a general class of tripartite composite fermion wave functions, which reduce to the Rezayi-Read ground state and quasiholes for appropriate quantum numbers, but also allow a construction of wave functions for quasiparticles and neutral excitations by analogy to the standard composite fermion theory. We present numerical evidence in finite systems that these trial wave functions capture well the low energy physics of a four-body model interaction. We also compare the tripartite composite fermion wave functions with the exact Coulomb eigenstates at 2+⅗, and find reasonably good agreement. The ground state as well as several excited states of the four-body interaction are seen to evolve adiabatically into the corresponding Coulomb states for N=15 particles. These results support the plausibility of the Read-Rezayi proposal for the 2+⅖ and 2+⅗ fractional quantum Hall effect. However, certain other proposals also remain viable, and further study of excitations and edge states will be necessary for a decisive establishment of the physical mechanism of these fractional quantum Hall states.
Topology and Fermionic Condensate
Kulikov, I.; Pronin, P.
The purpose of this paper is to investigate an influence of a space-time topology on the formation of fermionic condensate in the model with four-fermion interaction ()2. The value for the space-time with topology of R1 × R1 × S1 is found. Moreover a relation of the value of fermionic condensate to a periodic length is studied. In this connection the possibility of a relation of the topologic deposits to structure of hadrons is discussed.Translated AbstractTopologie und FermikondensatEs wird der Einfluß einer Raum-Zeittopologie auf die Bildung des Fermikondensats in einem Modell mit Vierfermionenwechselwirkung ()2 untersucht. Für eine Raum-Zeit mit der Topologie R1 × R2 × S1 werden die Parameter gegeben. Weiterhin wird die Relation der Größe des Fermikondensats zu einer periodischen Länge untersucht. In diesem Zusammenhang wird die Verbindung des topologischen Depots zur Struktur der Hadronen diskutiert.
Hadron Properties with FLIC Fermions
Energy Technology Data Exchange (ETDEWEB)
James Zanotti; Wolodymyr Melnitchouk; Anthony Williams; J Zhang
2003-07-01
The Fat-Link Irrelevant Clover (FLIC) fermion action provides a new form of nonperturbative O(a)-improvement in lattice fermion actions offering near continuum results at finite lattice spacing. It provides computationally inexpensive access to the light quark mass regime of QCD where chiral nonanalytic behavior associated with Goldstone bosons is revealed. The motivation and formulation of FLIC fermions, its excellent scaling properties and its low-lying hadron mass phenomenology are presented.
On free fermions and plane partitions
Foda, O; Zuparic, M
2008-01-01
We use free fermion methods to re-derive a result of Okounkov and Reshetikhin relating charged fermions to random plane partitions, and to extend it to relate neutral fermions to strict plane partitions.
Precision measurement of the positron asymmetry of laser-cooled, spin-polarized 37K
Melconian, Dan; Fenker, B.; Behr, J. A.; Anholm, M.; Ashery, D.; Behling, R. S.; Cohen, I.; Craiciu, I.; Gorelov, A.; Gwinner, G.; McNeil, J.; Mehlman, M.; Smale, S.; Warner, C. L.
2017-01-01
Precision low-energy measurements in nuclear β decay can be used to provide constraints on possible physics beyond the standard model, complementing searches at high-energy colliders. The short-lived isotope 37K was produced at ISAC-TRIUMF and confined in an alternating magneto-optical trap before being spin-polarized to 99.13(9)% via optical pumping. Our system allows for an exceptionally open geometry with the decay products escaping with their momenta unperturbed by the shallow trapping potential. The emitted positrons are detected in a pair of symmetric detectors placed along the polarization axis to measure the β asymmetry. The analysis was performed blind and considers β-scattering as well as other systematic effects. The results place limits on the mass of a hypothetical W boson coupling to right-handed neutrinos as well as contribute to an independent determination of the Vud element of the CKM matrix. The β asymmetry result as well as improvements and future plans will be described. This work is supported in part by the U.S. Department of Energy, the Natural Sciences and Engineering Research Council of Canada, and the Israel Science Foundation.
On Fermionic Entangled State Representation and Fermionic Entangled Wigner Operator
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
By analogy with the bosonic bipartite entangled state we construct fermionic entangled state with the Grassmann numbers. The Wigner operator in the fermionic entangled state representation is introduced, whose marginal distributions are understood in an entangled way. The technique of integration within an ordered product (IWOP) of Fermi operators is used in our discussion.
Supersymmetry for Fermion Masses
Institute of Scientific and Technical Information of China (English)
LIU Chun
2007-01-01
It is proposed that supersymmetry (SUSY) may be used to understand fermion mass hierarchies. A family symmetry Z3L is introduced, which is the cyclic symmetry among the three generation SU(2) doublets. SUSY breaks at a high energy scale ～ 1011 GeV. The electroweak energy scale ～ 100 GeV is unnaturally small. No additional global symmetry, like the R-parity, is imposed. The Yukawa couplings and R-parity violating couplings all take their natural values, which are (&)(100 ～ 10-2). Under the family symmetry, only the third generation charged fermions get their masses. This family symmetry is broken in the soft SUSY breaking terms, which result in a hierarchical pattern of the fermion masses. It turns out that for the charged leptons, the τ mass is fromthe Higgs vacuum expectation value (VEV)and the sneutrino VEVs, the muon mass is due to the sneutrino VEVs, and the electron gains its mass due to both Z3L and SUSY breaking. The large neutrino mixing are produced with neutralinos playing the partial role of right-handed neutrinos. |Ve3|, which is for ve-vτ mixing, is expected to be about 0.1. For the quarks, the third generation masses are from the Higgs VEVs, the second generation masses are from quantum corrections, and the down quark mass due to the sneutrino VEVs. It explains mc/ms, ms/me, md ＞ mu, and so on. Other aspects of the model are discussed.
Heavy fermion superconductivity
Brison, Jean-Pascal; Glémot, Loı̈c; Suderow, Hermann; Huxley, Andrew; Kambe, Shinsaku; Flouquet, Jacques
2000-05-01
The quest for a precise identification of the symmetry of the order parameter in heavy fermion systems has really started with the discovery of the complex superconducting phase diagram in UPt 3. About 10 years latter, despite numerous experiments and theoretical efforts, this is still not achieved, and we will quickly review the present status of knowledge and the main open question. Actually, the more forsaken issue of the nature of the pairing mechanism has been recently tackled by different groups with macroscopic or microscopic measurement, and significant progress have been obtained. We will discuss the results emerging from these recent studies which all support non-phonon-mediated mechanisms.
Phenomenology of high colour fermions
Energy Technology Data Exchange (ETDEWEB)
Lust, D.; Streng, K.H.; Papantonopoulos, E.; Zoupanos, G.
1986-04-28
We present the phenomenological consequences of a dynamical scenario for electroweak symmetry breaking and generation of fermion masses, involving the presence of fermions which transform under high colour representations. Particular emphasis is given to the predictions for rare processes and to the possible signals in present and future machines. (orig.).
Lindvall, T; Tittonen, I; Merimaa, M
2013-01-01
Many ion species commonly used for laser-cooled ion trapping studies have a low-lying metastable 2D3/2 state that can become populated due to spontaneous emission from the 2P1/2 excited state. This requires a repumper laser to maintain the ion in the Doppler cooling cycle. Typically the 2D3/2 state, or some of its hyperfine components if the ion has nuclear spin, has a higher multiplicity than the upper state of the repumping transition. This can lead to dark states, which have to be destabilized by an external magnetic field or by modulating the polarization of the repumper laser. We propose using unpolarized, incoherent amplified spontaneous emission (ASE) to drive the repumping transition. An ASE source offers several advantages compared to a laser. It prevents the buildup of dark states without external polarization modulation even in zero magnetic field, it can drive multiple hyperfine transitions simultaneously, and it requires no frequency stabilization. These features make it very compact and robust, ...
Espin, Johnny
2015-01-01
It has been proposed several times in the past that one can obtain an equivalent, but in many aspects simpler description of fermions by first reformulating their first-order (Dirac) Lagrangian in terms of two-component spinors, and then integrating out the spinors of one chirality ($e.g.$ primed or dotted). The resulting new Lagrangian is second-order in derivatives, and contains two-component spinors of only one chirality. The new second-order formulation simplifies the fermion Feynman rules of the theory considerably, $e.g.$ the propagator becomes a multiple of an identity matrix in the field space. The aim of this thesis is to work out the details of this formulation for theories such as Quantum Electrodynamics, and the Standard Model of elementary particles. After having developed the tools necessary to establish the second-order formalism as an equivalent approach to spinor field theories, we proceed with some important consistency checks that the new formulation is required to pass, namely the presence...
Multiple Isotope Magneto Optical Trap from a single diode laser
Valenzuela, V M; Gutierrez, M; Gomez, E; 10.1364/JOSAB.30.001205
2013-01-01
We present a Dual Isotope Magneto Optical Trap produced using a single diode laser. We generate all the optical frequencies needed for trapping both species using a fiber intensity modulator. All the optical frequencies are amplified simultaneously using a tapered amplifier. The independent control of each frequency is on the RF side rather than on the optical side. This introduces an enormous simplification for laser cooling applications that often require an acousto-optic modulator for each laser beam. Frequency changing capabilities are limited by the modulator bandwidth (10 GHz). Traps for more isotopes can be simply added by including additional RF frequencies to the modulator.
Tomographic probability representation for quantum fermion fields
Andreev, V A; Man'ko, V I; Son, Nguyen Hung; Thanh, Nguyen Cong; Timofeev, Yu P; Zakharov, S D
2009-01-01
Tomographic probability representation is introduced for fermion fields. The states of the fermions are mapped onto probability distribution of discrete random variables (spin projections). The operators acting on the fermion states are described by fermionic tomographic symbols. The product of the operators acting on the fermion states is mapped onto star-product of the fermionic symbols. The kernel of the star-product is obtained. The antisymmetry of the fermion states is formulated as the specific symmetry property of the tomographic joint probability distribution associated with the states.
Entanglement in fermionic Fock space
Sárosi, Gábor
2013-01-01
We propose a generalization of the usual SLOCC and LU classification of entangled pure state fermionic systems based on the Spin group. Our generalization uses the fact that there is a representation of this group acting on the fermionic Fock space which when restricted to fixed particle number subspaces recovers naturally the usual SLOCC transformations. The new ingredient is the occurrence of Bogoliubov transformations of the whole Fock space changing the particle number. The classification scheme built on the Spin group prohibits naturally entanglement between states containing even and odd number of fermions. In our scheme the problem of classification of entanglement types boils down to the classification of spinors where totally separable states are represented by so called pure spinors. We construct the basic invariants of the Spin group and show how some of the known SLOCC invariants are just their special cases. As an example we present the classification of fermionic systems with a Fock space based ...
Saxena, Pooja
2016-01-01
A search for high mass Higgs boson of the MSSM decaying into two fermions using the first 2015 data at 13 TeV is presented. The four final decay channels of mu \\tau_h, e \\tau_h, \\tau_h \\tau_h and e mu is used. The limits on production cross section times branching ratio has been set.Other results from Run1 and different searches and measurements involving Higgs decays fermions will also be reviewed.
Fermions as generalized Ising models
Wetterich, C.
2017-04-01
We establish a general map between Grassmann functionals for fermions and probability or weight distributions for Ising spins. The equivalence between the two formulations is based on identical transfer matrices and expectation values of products of observables. The map preserves locality properties and can be realized for arbitrary dimensions. We present a simple example where a quantum field theory for free massless Dirac fermions in two-dimensional Minkowski space is represented by an asymmetric Ising model on a euclidean square lattice.
Integrable Gross-Neveu models with fermion-fermion and fermion-antifermion pairing
Thies, Michael
2014-01-01
The massless Gross-Neveu and chiral Gross-Neveu models are well known examples of integrable quantum field theories in 1+1 dimensions. We address the question whether integrability is preserved if one either replaces the four-fermion interaction in fermion-antifermion channels by a dual interaction in fermion-fermion channels, or if one adds such a dual interaction to an existing integrable model. The relativistic Hartree-Fock-Bogoliubov approach is adequate to deal with the large N limit of such models. In this way, we construct and solve three integrable models with Cooper pairing. We also identify a candidate for a fourth integrable model with maximal kinematic symmetry, the "perfect" Gross-Neveu model. This type of field theories can serve as exactly solvable toy models for color superconductivity in quantum chromodynamics.
Xu, Liang; Yin, Yanning; Wei, Bin; Xia, Yong; Yin, Jianping
2016-01-01
More recently, laser cooling of the diatomic radical magnesium monofluoride (24Mg19F ) is being experimentally preformed [Appl. Phys. Express 8, 092701 (2015), 10.7567/APEX.8.092701 and Opt. Express 22, 28645 (2014), 10.1364/OE.22.028645] and was also studied theoretically [Phys. Rev. A 91, 042511 (2015), 10.1103/PhysRevA.91.042511]. However, some important problems still remain unsolved, so, in our paper, we perform further theoretical study for the feasibility of laser cooling and trapping the 24Mg19F molecule. At first, the highly diagonal Franck-Condon factors of the main transitions are verified by the closed-form approximation, Morse approximation, and Rydberg-Klein-Rees inversion methods, respectively. Afterwards, we investigate the lower X 2Σ1/2 + hyperfine manifolds using a quantum effective Hamiltonian approach and obtain the zero-field hyperfine spectrum with an accuracy of less than 30 kHz ˜5 μ K compared with the experimental results, and then find out that one cooling beam and one or two repumping beams with their first-order sidebands are enough to implement an efficient laser slowing and cooling of 24Mg19F . Meanwhile, we also calculate the accurate hyperfine structure magnetic g factors of the rotational state (X 2Σ1/2 +,N =1 ) and briefly discuss the influence of the external fields on the hyperfine structure of 24Mg19F as well as its possibility of preparing three-dimensional magneto-optical trapping. Finally we give an explanation for the difference between the Stark and Zeeman effects from the perspective of parity and time reversal symmetry. Our study shows that, besides appropriate excitation wavelengths, the short lifetime for the first excited state A 2Π1 /2 , and lighter mass, the 24Mg19F radical could be a good candidate molecule amenable to laser cooling and magneto-optical trapping.
Studying fermionic ghost imaging with independent photons
Liu, Jianbin; Zhou, Yu; Zheng, Huaibin; Chen, Hui; Li, Fu-li; Xu, Zhuo
2016-12-01
Ghost imaging with thermal fermions is calculated based on two-particle interference in Feynman's path integral theory. It is found that ghost imaging with thermal fermions can be simulated by ghost imaging with thermal bosons and classical particles. Photons in pseudothermal light are employed to experimentally study fermionic ghost imaging. Ghost imaging with thermal bosons and fermions is discussed based on the point-to-point (spot) correlation between the object and image planes. The employed method offers an efficient guidance for future ghost imaging with real thermal fermions, which may also be generalized to study other second-order interference phenomena with fermions.
Fermions on the electroweak string
Moreno, J M; Quirós, Mariano; Moreno, J M; Oaknin, D H; Quiros, M
1995-01-01
We construct a simple class of exact solutions of the electroweak theory including the naked Z--string and fermion fields. It consists in the Z--string configuration (\\phi,Z_\\theta), the {\\it time} and z components of the neutral gauge bosons (Z_{0,3},A_{0,3}) and a fermion condensate (lepton or quark) zero mode. The Z--string is not altered (no feed back from the rest of fields on the Z--string) while fermion condensates are zero modes of the Dirac equation in the presence of the Z--string background (no feed back from the {\\it time} and z components of the neutral gauge bosons on the fermion fields). For the case of the n--vortex Z--string the number of zero modes found for charged leptons and quarks is (according to previous results by Jackiw and Rossi) equal to |n|, while for (massless) neutrinos is |n|-1. The presence of fermion fields in its core make the obtained configuration a superconducting string, but their presence (as well as that of Z_{0,3},A_{0,3}) does not enhance the stability of the Z--stri...
Fermion production during and after axion inflation
Energy Technology Data Exchange (ETDEWEB)
Adshead, Peter; Sfakianakis, Evangelos I. [Department of Physics, University of Illinois at Urbana-Champaign,Urbana, Illinois 61801 (United States)
2015-11-11
We study derivatively coupled fermions in axion-driven inflation, specifically m{sub ϕ}{sup 2}ϕ{sup 2} and monodromy inflation, and calculate particle production during the inflationary epoch and the post-inflationary axion oscillations. During inflation, the rolling axion acts as an effective chemical potential for helicity which biases the gravitational production of one fermion helicity over the other. This mechanism allows for efficient gravitational production of heavy fermion states that would otherwise be highly suppressed. Following inflation, the axion oscillates and fermions with both helicities are produced as the effective frequency of the fermion field changes non-adiabatically. For certain values of the fermion mass and axion-fermion coupling strength, the two helicity states are produced asymmetrically, resulting in unequal number-densities of left- and right-helicity fermions.
Acoustoelectric current for composite fermions
Bergli, J.; Galperin, Y. M.
2001-07-01
The acoustoelectric current for composite fermions in a two-dimensional electron gas (2DEG) close to the half-filled Landau level is calculated in the random phase approximation. The Boltzmann equation is used to find the nonequilibrium distribution of composite fermions to second order in the acoustic field. It is shown that the oscillating Chern-Simons field created by the induced density fluctuations in the 2DEG is important for the acoustoelectric current. This leads to a violation of the Weinreich relation between the acoustoelectric current and acoustic intensity. The deviations from the Weinreich relation can be detected by measuring the angle between the longitudinal and the Hall components of the acoustoelectric current. This departure from the Weinreich relation gives additional information on the properties of the composite fermion fluid.
Dynamical fermion masses under the influence of Kaluza-Klein fermions in extra dimensions
Abe, Hiroyuki; Miguchi, Hironori; Muta, Taizo
2000-01-01
The dynamical fermion mass generation in the 4-dimensional brane is discussed in a model with 5-dimensional Kaluza-Klein fermions in interaction with 4-dimensional fermions. It is found that the dynamical fermion masses are generated beyond the critical radius of the compactified extra dimensional space and may be made small compared with masses of the Kaluza-Klein modes.
Dynamical fermion masses under the influence of Kaluza-Klein fermions in extra dimensions
Abe, H; Muta, T; Abe, Hiroyuki; Miguchi, Hironori; Muta, Taizo
2000-01-01
The dynamical fermion mass generation in the 4-dimensional brane is discussedin a model with 5-dimensional Kaluza-Klein fermions in interaction with4-dimensional fermions. It is found that the dynamical fermion masses aregenerated beyond the critical radius of the compactified extra dimensionalspace and may be made small compared with masses of the Kaluza-Klein modes.
Application of Semiconductor Refrigeration to Laser Cooling System%热电制冷在激光器冷却系统中的应用
Institute of Scientific and Technical Information of China (English)
高光波; 郑四木
2012-01-01
Through a typical cooling solutions, the applications of thermoelectric cooling in laser cooling systems were introduced. A three-step cooling program design was proposed through experimental data to guide the cooling design. The cooling scheme was further optimized by thermal simulation. Through the thermal test technology to verify whether the cooling system to meet the demand of practical work, the method improves the efficiency of the cooling system design laid the foundation for laser cooling systems serialization and modular.%通过一种典型的冷却方案介绍热电制冷在激光器冷却系统中的应用,提出了以实验数据指导冷却方案设计,以热仿真手段进一步优化冷却方案,最终通过热测试技术验证冷却系统是否满足激光器的实际工作要求的三步走设计方法,该方法提高了热电制冷方案设计效率,为激光器冷却系统系列化、模块化打下基础.
Fu, Mingkai; Ma, Haitao; Cao, Jianwei; Bian, Wensheng
2017-04-07
Owing to the exciting potential applications of ultracold atoms and molecules in many fields, developing new cooling schemes has attracted great interests in recent years. Here, we investigate laser cooling of CaBr molecules and design a photonic scheme for the production of ultracold Br atoms using the highly accurate ab initio and dynamical methods. We find that the AΠ1/22(ν(')=0)→X(2)Σ1/2(+)(ν=0) transition for CaBr features a large vibrational branching ratio, a significant photon-scattering rate, and no intermediate electronic-state interference, indicating that the ultracold CaBr could be produced through a three-laser cooling scheme. Moreover, an efficient four-pulse excitation scheme from the ground rovibrational level of the cooled CaBr molecules is proposed to yield ultracold Br atoms, in which a few spin-orbit excited states are utilized as the intermediate states. The importance of the spin-orbit coupling is underscored in this work.
Bosonic behavior of entangled fermions
DEFF Research Database (Denmark)
C. Tichy, Malte; Alexander Bouvrie, Peter; Mølmer, Klaus
2012-01-01
Two bound, entangled fermions form a composite boson, which can be treated as an elementary boson as long as the Pauli principle does not affect the behavior of many such composite bosons. The departure of ideal bosonic behavior is quantified by the normalization ratio of multi-composite-boson st......Two bound, entangled fermions form a composite boson, which can be treated as an elementary boson as long as the Pauli principle does not affect the behavior of many such composite bosons. The departure of ideal bosonic behavior is quantified by the normalization ratio of multi...
Fermions as generalized Ising models
Directory of Open Access Journals (Sweden)
C. Wetterich
2017-04-01
Full Text Available We establish a general map between Grassmann functionals for fermions and probability or weight distributions for Ising spins. The equivalence between the two formulations is based on identical transfer matrices and expectation values of products of observables. The map preserves locality properties and can be realized for arbitrary dimensions. We present a simple example where a quantum field theory for free massless Dirac fermions in two-dimensional Minkowski space is represented by an asymmetric Ising model on a euclidean square lattice.
Dynamical fermions in lattice quantum chromodynamics
Energy Technology Data Exchange (ETDEWEB)
Szabo, Kalman
2007-07-01
The thesis presentS results in Quantum Chromo Dynamics (QCD) with dynamical lattice fermions. The topological susceptibilty in QCD is determined, the calculations are carried out with dynamical overlap fermions. The most important properties of the quark-gluon plasma phase of QCD are studied, for which dynamical staggered fermions are used. (orig.)
Theoretical studies of strongly correlated fermions
Energy Technology Data Exchange (ETDEWEB)
Logan, D. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)
1997-04-01
Strongly correlated fermions are investigated. An understanding of strongly correlated fermions underpins a diverse range of phenomena such as metal-insulator transitions, high-temperature superconductivity, magnetic impurity problems and the properties of heavy-fermion systems, in all of which local moments play an important role. (author).
Fermion Determinant with Dynamical Chiral Symmetry Breaking
Institute of Scientific and Technical Information of China (English)
LU Qin; YANG Hua; WANG Qing
2002-01-01
One-loop fermion determinant is discussed for the case in which the dynamical chiral symmetry breakingcaused by momentum-dependent fermion self-energy ∑(p2) takes place. The obtained series generalizes the heat kernelexpansion for hard fermion mass.
Fermion Determinants: Some Recent Analytic Results
Fry, M P
2004-01-01
The use of known analytic results for the continuum fermion determinants in QCD and QED as benchmarks for zero lattice spacing extrapolations of lattice fermion determinants is proposed. Specifically, they can be used as a check on the universality hypothesis relating the continuum limits of the na\\"{\\i}ve, staggered and Wilson fermion determinants.
Scale Of Fermion Mass Generation
Niczyporuk, J M
2002-01-01
Unitarity of longitudinal weak vector boson scattering implies an upper bound on the scale of electroweak symmetry breaking, Λ EWSB ≡ 8pv ≈ 1 TeV. Appelquist and Chanowitz have derived an analogous upper bound on the scale of fermion mass generation, proportional to v 2/mf, by considering the scattering of same-helicity fermions into pairs of longitudinal weak vector bosons in a theory without a standard Higgs boson. We show that there is no upper bound, beyond that on the scale of electroweak symmetry breaking, in such a theory. This result is obtained by considering the same process, but with a large number of longitudinal weak vector bosons in the final state. We further argue that there is no scale of (Dirac) fermion mass generation in the standard model. In contrast, there is an upper bound on the scale of Majorana-neutrino mass generation, given by ΛMaj ≡ 4πv2/m ν. In general, the upper bound on the scale of fermion mass generation depend...
Light Front Fermion Model Propagation
Institute of Scientific and Technical Information of China (English)
Jorge Henrique Sales; Alfredo Takashi Suzuki
2013-01-01
In this work we consider the propagation of two fermion fields interacting with each other by the exchange of intermediate scalar bosons in the light front.We obtain the corrections up to fourth order in the coupling constant using hierarchical equations in order to obtain the bound state equation (Bethe-Salpeter equation).
Gravitational contribution to fermion masses
Tiemblo, A; Tiemblo, Alfredo; Tresguerres, Romualdo
2005-01-01
In the context of a nonlinear gauge theory of the Poincar\\'e group, we show that covariant derivatives of Dirac fields include a coupling to the translational connections, manifesting itself in the matter action as a universal background mass contribution to fermions.
Constructing entanglement measures for fermions
Johansson, Markus; Raissi, Zahra
2016-10-01
In this paper we describe a method for finding polynomial invariants under stochastic local operations and classical communication (SLOCC) for a system of delocalized fermions shared between different parties, with global particle-number conservation as the only constraint. These invariants can be used to construct entanglement measures for different types of entanglement in such a system. It is shown that the invariants, and the measures constructed from them, take a nonzero value only if the state of the system allows for the observation of Bell-nonlocal correlations. Invariants of this kind are constructed for systems of two and three spin-1/2 fermions and examples of maximally entangled states are given that illustrate the different types of entanglement distinguished by the invariants. A general condition for the existence of SLOCC invariants and their associated measures is given as a relation between the number of fermions, their spin, and the number of spatial modes of the system. In addition, the effect of further constraints on the system, including the localization of a subset of the fermions, is discussed. Finally, a hybrid Ising-Hubbard Hamiltonian is constructed for which the ground state of a three-site chain exhibits a high degree of entanglement at the transition between a regime dominated by on-site interaction and a regime dominated by Ising interaction. This entanglement is well described by a measure constructed by the introduced method.
Levi, T; Levi, Thomas s.; Gleiser, Marcelo
2002-01-01
We present a new model for a non-topological soliton (NTS) that contains fermions, scalar particles and a gauge field. Using a variational approach, we estimate the energy of the localized configuration, showing that it can be the lowest energy state of the system for a wide range of parameters.
Gravitational contribution to fermion masses
Tiemblo, Alfredo; Tresguerres, Romualdo
2005-01-01
In the context of a nonlinear gauge theory of the Poincar\\'e group, we show that covariant derivatives of Dirac fields include a coupling to the translational connections, manifesting itself in the matter action as a universal background mass contribution to fermions.
Gravitational contribution to fermion masses
Energy Technology Data Exchange (ETDEWEB)
Tiemblo, A.; Tresguerres, R. [Consejo Superior de Investigaciones Cientificas, Instituto de Matematicas y Fisica Fundamental, Madrid (Spain)
2005-08-01
In the context of a non-linear gauge theory of the Poincare group, we show that covariant derivatives of Dirac fields include a coupling to the translational connections, manifesting itself in the matter action as a universal background mass contribution to fermions. (orig.)
The Gaussian entropy of fermionic systems
Energy Technology Data Exchange (ETDEWEB)
Prokopec, Tomislav, E-mail: T.Prokopec@uu.nl [Institute for Theoretical Physics (ITP) and Spinoza Institute, Utrecht University, Postbus 80195, 3508 TD Utrecht (Netherlands); Schmidt, Michael G., E-mail: M.G.Schmidt@thphys.uni-heidelberg.de [Institut fuer Theoretische Physik, Heidelberg University, Philosophenweg 16, D-69120 Heidelberg (Germany); Weenink, Jan, E-mail: J.G.Weenink@uu.nl [Institute for Theoretical Physics (ITP) and Spinoza Institute, Utrecht University, Postbus 80195, 3508 TD Utrecht (Netherlands)
2012-12-15
We consider the entropy and decoherence in fermionic quantum systems. By making a Gaussian Ansatz for the density operator of a collection of fermions we study statistical 2-point correlators and express the entropy of a system fermion in terms of these correlators. In a simple case when a set of N thermalised environmental fermionic oscillators interacts bi-linearly with the system fermion we can study its time dependent entropy, which also represents a quantitative measure for decoherence and classicalization. We then consider a relativistic fermionic quantum field theory and take a mass mixing term as a simple model for the Yukawa interaction. It turns out that even in this Gaussian approximation, the fermionic system decoheres quite effectively, such that in a large coupling and high temperature regime the system field approaches the temperature of the environmental fields. - Highlights: Black-Right-Pointing-Pointer We construct the Gaussian density operator for relativistic fermionic systems. Black-Right-Pointing-Pointer The Gaussian entropy of relativistic fermionic systems is described in terms of 2-point correlators. Black-Right-Pointing-Pointer We explicitly show the growth of entropy for fermionic fields mixing with a thermal fermionic environment.
Towards high precision measurements of nuclear g-factors for the Be isotopes
Energy Technology Data Exchange (ETDEWEB)
Takamine, A., E-mail: icot@riken.jp [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Wada, M. [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Okada, K. [Department of Physics, Sophia University, Chiyoda Ward, Tokyo (Japan); Ito, Y. [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Schury, P.; Arai, F. [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Institute of Physics, University of Tsukuba, Tsukuba City, Ibaraki (Japan); Katayama, I. [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Imamura, K. [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Department of Physics, Meiji University, Kawasaki City, Kanagawa (Japan); Ichikawa, Y.; Ueno, H. [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Wollnik, H. [Department of Chemistry and BioChemistry, New Mexico State University, Las Cruces, NM (United States); Schuessler, H.A. [Department of Physics, Texas A& M University, College Station, TX (United States)
2016-06-01
We describe the present status of future high-precision measurements of nuclear g-factors utilizing laser-microwave double and laser-microwave-rf triple resonance methods for online-trapped, laser-cooled radioactive beryllium isotope ions. These methods have applicability to other suitably chosen isotopes and for beryllium show promise in deducing the hyperfine anomaly of {sup 11}Be with a sufficiently high precision to study the nuclear magnetization distribution of this one-neutron halo nucleus in a nuclear-model-independent manner.
Thermometry of Cr Laser Cooling via Knife-Edge%刀口法测量铬原子激光冷却温度
Institute of Scientific and Technical Information of China (English)
焦晓光; 殷聪; 石春英; 钱进
2011-01-01
The principle of knife-edge thermometry is introduced. A chromium beam which is jetted from high temperature atomic crucible is collimated by one-dimensional laser Doppler cooling on self-designed system of chromium atom lithography. The laser wavelength in vacuum is 425. 5 nm, corresponding to 7S3-?-7P? Transition of 52Cr. The setup of knife-edge thermometry is designed and built to quantify the effect of the chromium beam collimation by laser cooling. The obvious cooling phenomenon is observed with power of 45 mW, spot size of 1 mmX 20 mm and detuning of -2.5 MHz. Then, based on it, the knife-edge measurement is carried out. The results show that the full-width at half-maximum (FWHM) of chromium beam angular distribution is (0. 616±0. 007) mrad and the transverse temperature is (418 ± 10) pK by laser cooling. The results provide a basis for optimizing the chromium beam collimation by laser cooling.%介绍了刀口法测温原理.在自主研制的铬原子光刻系统上,利用稳定到52Cr的7 S3→7P_4~0跃迁上的真空波长为425.5 nm的激光,对高温原子炉喷射的铬原子束进行了一维多普勒冷却准直.设计搭建了刀口法测温实验装置,对激光多普勒冷却准直效果进行了定量评价.在激光功率为45 mW,失谐量为-2.5 MHz,光斑大小为1 mm × 20 mm的条件下,观察到了明显的冷却现象.在此基础上采用刀口法测温,测得激光冷却后铬原子束角分布的半峰全宽为(0.616±0.007) mrad,横向温度为(418±10)μK.这些结果为优化调整铬原子束激光冷却准直实验提供了依据.
Nuclear charge radius measurements of radioactive beryllium isotopes
2002-01-01
We propose to measure the nuclear charge radii of the beryllium isotopes $^{7,9,10}$Be and the one-neutron halo isotope $^{11}$Be using laser spectroscopy of trapped ions. Ions produced at ISOLDE and ionized with the laser ion source will be cooled and bunched in the radio-frequency buncher of the ISOLTRAP experiment and then transferred into a specially designed Paul trap. Here, they will be cooled to temperatures in the mK range employing sympathetic and direct laser cooling. Precision laser spectroscopy of the isotope shift on the cooled ensemble in combination with accurate atomic structure calculations will provide nuclear charge radii with a precision of better than 3%. This will be the first model-independent determination of a one-neutron halo nuclear charge radius.
Jia, You-Hua; Zhong, Biao; Yin, Jian-Ping
2009-03-01
The enhanced laser cooling performance of rare-earth-ions-doped glasses containing small particles is predicted. This is achieved by the enhancement of local field around rare earth ions, owing to the surface plasmon resonance of small metallic particles. The role of energy transfer between ions and the particle is theoretical discussed. Depending on the particle size and the ion emission quantum efficiency, the enhancement of the absorption and the fluorescence is predicted. Moreover, taking Yb3+ -doped ZBLAN as example, the cooling power and heat-light converting efficiency are calculated. It is finally concluded that the absorption and the fluorescence are greatly enhanced in these composite materials, the cooling power is increased compared to the bulk material.
Directory of Open Access Journals (Sweden)
Inoue T.
2014-03-01
Full Text Available We plan to measure the permanent electric dipole moment (EDM of the electron, which has the sensitivity to the CP violation in theories beyond the standard model by using the laser-cooled francium (Fr atom. This paper reports the present status of the EDM measurement system. A high voltage application system was constructed in order to produce the strong electric field (100 kV/cm needed for the experiment. After conditioning, the leakage current was 10 pA when a high voltage of 43 kV was applied. Also, a drift of an environmental field was measured at the planned location of the Fr-EDM experiment. The drift is suppressed at present down to the level of 10 pT by installing a 4-layermagnetic shield. Improvements are still needed to reach the required field stability of 1 fT.
Saß, Anne; Christopoulos, Stavros; Knicker, Katharina; Moroshkin, Peter; Weitz, Martin
2014-01-01
We study laser cooling of atomic gases by collisional redistribution of fluorescence. In a high pressure buffer gas regime, frequent collisions perturb the energy levels of alkali atoms, which allows for the absorption of a far red detuned irradiated laser beam. Subsequent spontaneous decay occurs close to the unperturbed resonance frequency, leading to a cooling of the dense gas mixture by redistribution of fluorescence. Thermal deflection spectroscopy indicates large relative temperature changes down to and even below room temperature starting from an initial cell temperature near 700 K. We are currently performing a detailed analysis of the temperature distribution in the cell. As we expect this cooling technique to work also for molecular-noble gas mixtures, we also present initial spectroscopic experiments on alkali-dimers in a dense buffer gas surrounding.
Polarization of fermions in a vorticular fluid
Fang, Ren-hong; Wang, Qun; Wang, Xin-nian
2016-01-01
Fermions become polarized in a vorticular fluid due to spin-vorticity coupling. Such a polarization can be calculated from the Wigner function in a quantum kinetic approach. Extending previous results for chiral fermions, we derive the Wigner function for massive fermions up to the next-to-leading order in spatial gradient expansion. The polarization density of fermions can be calculated from the axial vector component of the Wigner function and is found to be proportional to the local vorticity $\\omega$. The polarizations per particle for fermions and anti-fermions decrease with the chemical potential and increase with energy (mass). Both quantities approach the asymptotic value $\\hbar\\omega/4$ in the large energy (mass) limit. The polarization per particle for fermions is always smaller than that for anti-fermions, whose ratio of fermions to anti-fermions also decreases with the chemical potential. The polarization per particle on the Cooper-Frye freeze-out hyper-surface can also be formulated and is consis...
Sarkar, Sujit
2014-01-01
Quantum simulation aims to simulate a quantum system using a controble laboratory system that underline the same mathematical model. Cavity QED lattice system is that prescribe system to simulate the relativistic quantum effect. We quantum simulate the Dirac fermion mode, Majorana fermion mode and Majorana-Weyl fermion mode and a crossover between them in cavity QED lattice. We also present the different analytical relations between the field operators for different mode excitations.
Duality group actions on fermions
Pantev, Tony; Sharpe, Eric
2016-11-01
In this short paper we look at the action of T-duality and string duality groups on fermions, in maximally-supersymmetric theories and related theories. Briefly, we argue that typical duality groups such as SL(2 , ℤ) have sign ambiguities in their actions on fermions, and propose that pertinent duality groups be extended by ℤ2, to groups such as the metaplectic group. Specifically, we look at duality groups arising from mapping class groups of tori in M theory compactifications, T-duality, ten-dimensional type IIB S-duality, and (briefly) four-dimensional N = 4 super Yang-Mills, and in each case, propose that the full duality group is a nontrivial ℤ2 extension of the duality group acting on bosonic degrees of freedom, to more accurately describe possible actions on fermions. We also walk through U-duality groups for toroidal compactifications to nine, eight, and seven dimensions, which enables us to perform cross-consistency tests of these proposals.
Duality group actions on fermions
Pantev, T
2016-01-01
In this short paper we look at the action of T-duality and string duality groups on fermions, in maximally-supersymmetric theories and related theories. Briefly, we argue that typical duality groups such as SL(2,Z) have sign ambiguities in their actions on fermions, and propose that pertinent duality groups be extended by Z_2, to groups such as the metaplectic group. Specifically, we look at duality groups arising from mapping class groups of tori in M theory compactifications, T-duality, ten-dimensional type IIB S-duality, and (briefly) four-dimensional N=4 super Yang-Mills, and in each case, propose that the full duality group is a nontrivial Z_2 extension of the duality group acting on bosonic degrees of freedom, to more accurately describe possible actions on fermions. We also walk through U-duality groups for toroidal compactifications to nine, eight, and seven dimensions, which enables us to perform cross-consistency tests of these proposals.
Fermion RG blocking transformations and IR structure
Cheng, X
2011-01-01
We explore fermion RG block-spinning transformations on the lattice with the aim of studying the IR structure of gauge theories and, in particular, the existence of IR fixed points for varying fermion content. In the case of light fermions the main concern and difficulty is ensuring locality of any adopted blocking scheme. We discuss the problem of constructing a local blocked fermion action in the background of arbitrary gauge fields. We then discuss the carrying out of accompanying gauge field blocking. In the presence of the blocked fermions implementation of MCRG is not straightforward. By adopting judicious approximations we arrive at an easily implementable approximate RG recursion scheme that allows quick, inexpensive estimates of the location of conformal windows for various groups and fermion representations. We apply this scheme to locate the conformal windows in the case of SU(2) and SU(3) gauge groups. Some of the reasons for the apparent efficacy of this and similar decimation schemes are discuss...
Truncated Perfect Actions for Staggered Fermions
Bietenholz, W
1998-01-01
We discuss the behavior of free perfect staggered fermions and truncated versions thereof. The study includes flavor non-degenerate masses. We suggest a new blocking scheme, which provides excellent locality of the perfect lattice action. A truncation procedure adequate for the structure of staggered fermions is applied. We consider spectral and thermodynamic properties and compare truncated perfect actions, Symanzik improved and standard staggered fermions in two and four dimensions.
Perfect Lattice Actions for Staggered Fermions
Bietenholz, W; Chandrasekharan, S; Wiese, U J
1996-01-01
We construct a perfect lattice action for staggered fermions by blocking from the continuum. The locality, spectrum and pressure of such perfect staggered fermions are discussed. We also derive a consistent fixed point action for free gauge fields and discuss its locality as well as the resulting static quark-antiquark potential. This provides a basis for the construction of (classically) perfect lattice actions for QCD using staggered fermions.
Lattice quantum chromodynamics with approximately chiral fermions
Energy Technology Data Exchange (ETDEWEB)
Hierl, Dieter
2008-05-15
In this work we present Lattice QCD results obtained by approximately chiral fermions. We use the CI fermions in the quenched approximation to investigate the excited baryon spectrum and to search for the {theta}{sup +} pentaquark on the lattice. Furthermore we developed an algorithm for dynamical simulations using the FP action. Using FP fermions we calculate some LECs of chiral perturbation theory applying the epsilon expansion. (orig.)
Dynamical Fermion Masses Under the Influence of Kaluza-Klein Fermions in Randall-Sundrum Background
Abe, H; Muta, T; Abe, Hiroyuki; Inagaki, Tomohiro; Muta, Taizo
2001-01-01
The dynamical fermion mass generation on the D3-brane in the Randall-Sundrum space-time is discussed in a model with bulk fermions in interaction with fermions on the branes. It is found that the dynamical fermion masses are generated at the natural (R.-S.) radius of the compactified extra space and may be made small compared with masses of the Kaluza-Klein modes which is of order of TeV.
Dynamical fermion masses under the influence of Kaluza-Klein fermions in extradimensions
Abe, Hiroyuki; Miguchi, Hironori; Muta, Taizo
2000-01-01
The dynamical fermion mass generation in the 4-dimensional brane is discussed in a model with 5-dimensional Kaluza-Klein fermions in interaction with 4-dimensional fermions. It is found that the dynamical fermion masses are generated beyond the critical radius of the compactified extra dimensional space and may be made small compared with masses of the Kaluza-Klein modes. 04.50.th, 04.60.-m, 11.15.Pg, 11.30.Qc
Lattice Chiral Fermions Through Gauge Fixing
Bock, W; Shamir, Y; Bock, Wolfgang; Golterman, Maarten; Shamir, Yigal
1998-01-01
We study a concrete lattice regularization of a U(1) chiral gauge theory. We use Wilson fermions, and include a Lorentz gauge-fixing term and a gauge-boson mass counterterm. For a reduced version of the model, in which the gauge fields are constrained to the trivial orbit, we show that there are no species doublers, and that the fermion spectrum contains only the desired states in the continuum limit, namely charged left-handed (LH) fermions and neutral right-handed (RH) fermions.
Fermionic quantum critical point of spinless fermions on a honeycomb lattice
Wang, L.; Corboz, P.; Troyer, M.
2014-01-01
Spinless fermions on a honeycomb lattice provide a minimal realization of lattice Dirac fermions. Repulsive interactions between nearest neighbors drive a quantum phase transition from a Dirac semimetal to a charge-density-wave state through a fermionic quantum critical point, where the coupling of
Scalar spin of elementary fermions
Energy Technology Data Exchange (ETDEWEB)
Jourjine, A., E-mail: jourjine@pks.mpg.de
2014-01-20
We show that, using the experimentally observed values of CKM and PMNS mixing matrices, all known elementary fermions can be assigned a new quantum number, the scalar spin, in a unique way. This is achieved without introduction of new degrees of freedom. The assignment implies that tau-neutrino should be an anti-Dirac spinor, while mu–tau leptons and charm–top, strange–bottom quarks form Dirac–anti-Dirac scalar spin doublets. The electron and its neutrino remain as originally described by Dirac.
Light fermions in composite models
Khlebnikov, S. Yu.; Peccei, R. D.
1993-07-01
In preon models based on chiral gauge theories, we show that light composite fermions can ensue as a result of gauging a subset of preons in a vectorlike manner. After demonstrating how this mechanism works in a toy example, we construct a one-generation model of quarks which admits a hierarchy between the up and down quark masses as well as between these masses and the compositeness scale. In simple extensions of this model to more generations we discuss the challenges of obtaining any quark mixing. Some possible phenomenological implications of scenarios where quarks and leptons which are heavier are also less pointlike are also considered.
Light fermions in composite models
Khlebnikov, S Yu
1993-01-01
In preon models based on chiral gauge theories, we show that light composite fermions can ensue as a result of gauging a subset of preons in a vector-like manner. After demonstrating how this mechanism works in a toy example, we construct a one generation model of quarks which admits a hierarchy between the up and down quark masses as well as between these masses and the compositeness scale. In simple extensions of this model to more generations we discuss the challenges of obtaining any quark mixing. Some possible phenomenological implications of scenarios where quarks and leptons which are heavier are also less pointlike are also considered.
Chiral Fermions on the Lattice
Bietenholz, Wolfgang
2010-01-01
In the last century the non-perturbative regularization of chiral fermions was a long-standing problem. We review how this problem was finally overcome by the formulation of a modified but exact form of chiral symmetry on the lattice. This also provides a sound definition of the topological charge of lattice gauge configurations. We illustrate a variety of applications to QCD in the p-, the epsilon- and the delta-regime, where simulation results can now be related to Random Matrix Theory and Chiral Perturbation Theory. The latter contains Low Energy Constants as free parameters, and we comment on their evaluation from first principles of QCD.
Fermionic models with superconducting circuits
Energy Technology Data Exchange (ETDEWEB)
Las Heras, Urtzi; Garcia-Alvarez, Laura; Mezzacapo, Antonio; Lamata, Lucas [University of the Basque Country UPV/EHU, Department of Physical Chemistry, Bilbao (Spain); Solano, Enrique [University of the Basque Country UPV/EHU, Department of Physical Chemistry, Bilbao (Spain); IKERBASQUE, Basque Foundation for Science, Bilbao (Spain)
2015-12-01
We propose a method for the efficient quantum simulation of fermionic systems with superconducting circuits. It consists in the suitable use of Jordan-Wigner mapping, Trotter decomposition, and multiqubit gates, be with the use of a quantum bus or direct capacitive couplings. We apply our method to the paradigmatic cases of 1D and 2D Fermi-Hubbard models, involving couplings with nearest and next-nearest neighbours. Furthermore, we propose an optimal architecture for this model and discuss the benchmarking of the simulations in realistic circuit quantum electrodynamics setups. (orig.)
Fermion Dipole Moment and Holography
Kulaxizi, Manuela
2015-01-01
In the background of a charged AdS black hole, we consider a Dirac particle endowed with an arbitrary magnetic dipole moment. For non-zero charge and dipole coupling of the bulk fermion, we find that the dual boundary theory can be plagued with superluminal modes. Requiring consistency of the dual CFT amounts to constraining the strength of the dipole coupling by an upper bound. We briefly discuss the implications of our results for the physics of holographic non-Fermi liquids.
Lindvall, T; Tittonen, I; Madej, A A; 10.1103/PhysRevA.86.033403
2012-01-01
We study the formation and destabilization of dark states in a single trapped 88Sr+ ion caused by the cooling and repumping laser fields required for Doppler cooling and fluorescence detection of the ion. By numerically solving the time-dependent density matrix equations for the eight-level system consisting of the sublevels of the 5s 2S1/2, 5p 2P1/2, and 4d 2D3/2 states, we analyze the different types of dark states and how to prevent them in order to maximize the scattering rate, which is crucial for both the cooling and the detection of the ion. The influence of the laser linewidths and ion motion on the scattering rate and the dark resonances is studied. The calculations are then compared with experimental results obtained with an endcap ion trap system located at the National Research Council of Canada and found to be in good agreement. The results are applicable also to other alkaline earth ions and isotopes without hyperfine structure.
LHC Higgs boson results involving fermions
Chen, X; The ATLAS collaboration
2013-01-01
Following the discovery of a Higgs-like particle in the bosonic decay modes, the fermionic decay modes need to be seen to prove this particle is a Standard Model (SM) Higgs. In this presentation, an overview of the recent Higgs search results in the fermionic decays of $\\tau\\tau$, $b\\bar{b}$, $\\mu\\mu$ and $\\tau\
The generalized fermion-bag approach
Chandrasekharan, Shailesh
2011-01-01
We present a new approach to some four-fermion lattice field theories which we call the generalized fermion bag approach. The basic idea is to identify unpaired fermionic degrees of freedom that cause sign problems and collect them in a bag. Paired fermions usually act like bosons and do not lead to sign problems. A resummation of all unpaired fermion degrees of freedom inside the bag is sufficient to solve the fermion sign problem in a variety of interesting cases. Using a concept of duality we then argue that the size of the fermion bags is small both at strong and weak couplings. This allows us to construct efficient algorithms in both these limits. Using the fermion bag approach, we study the quantum phase transition of the 3D massless lattice Thirrring model which is of interest in the context of Graphene. Using our method we are able to solve the model on lattices as large as $40^3$ with moderate computational resources. We obtain the precise location of the quantum critical point and the values of the ...
On localization of Dirac fermions by disorder
Medvedyeva, Mariya Vyacheslavivna
2011-01-01
This thesis is devoted to the effects of disorder on two-dimensional systems of Dirac fermions. Disorder localizes the usual electron system governed by the Schroedinger equation. The influence of disorder on Dirac fermions is qualitevely different. We concentrate on a random mass term in the Dira
Coherent states in the fermionic Fock space
Oeckl, Robert
2015-01-01
We construct the coherent states in the sense of Gilmore and Perelomov for the fermionic Fock space. Our treatment is from the outset adapted to the infinite-dimensional case. The fermionic Fock space becomes in this way a reproducing kernel Hilbert space of continuous holomorphic functions.
QCD with Flavored Minimally Doubled Fermions
Weber, Johannes Heinrich
2016-01-01
I discuss minimally doubled fermions fermions as an ultra-local formulation on the lattice for sea quarks that realize a non-singlet chiral symmetry. I introduce a non-singlet mass term for Karsten-Wilczek fermions and identify the appropriate representation of the SU(2) flavor group at finite lattice spacing. I present an algebraic proof that the symmetry of the quark determinant under charge conjugation and reflections of the Euclidean axes is preserved for Karsten-Wilczek fermions as sea quarks. Finally, I discuss how the flavor components in meson correlation functions with Karsten-Wilczek fermions emerge naturally and I show how taste-breaking can be avoided without fine tuning.
Fermionic T-duality: A snapshot review
Colgáin, Eoin Ó
2012-01-01
Through a self-dual mapping of the geometry AdS5 x S5, fermionic T-duality provides a beautiful geometric interpretation of hidden symmetries for scattering amplitudes in N=4 super-Yang-Mills. Starting with Green-Schwarz sigma-models, we consolidate developments in this area into this small review. In particular, we discuss the translation of fermionic T-duality into the supergravity fields via pure spinor formalism and show that a general class of fermionic transformations can be identified directly in the supergravity. In addition to discussing fermionic T-duality for the geometry AdS4 x CP3, dual to N=6 ABJM theory, we review work on other self-dual geometries. Finally, we present a short round-up of studies with a formal interest in fermionic T-duality.
Boson--Fermion hybrid representation formulation, I
Energy Technology Data Exchange (ETDEWEB)
Wu, C.; Feng, D.H.
1981-08-01
A boson--fermion hybrid representation is presented. In this framework, a fermion system is described concurrently by the bosonic and the fermonic degrees of freedom. A fermion pair in this representation can be treated as a boson without violating the Pauli principle. Furthermore the ''bosonic interactions'' are shown to originate from the exchange processes of the fermions and can be calculated from the original fermion interactions. Both the formulation of the BFH representations for the even and odd nuclear systems are given. We find that the basic equation of the nuclear field theory (NFT) is just the usual Schroedinger equation in such a representation with the empirical NFT diagrammatic rules emerging naturally. This theory was numerically checked in the case of four nucleons moving in a single-j shell and the exactness of the theory was established.
Fixed Point Actions for Lattice Fermions
Bietenholz, W
1994-01-01
The fixed point actions for Wilson and staggered lattice fermions are determined by iterating renormalization group transformations. In both cases a line of fixed points is found. Some points have very local fixed point actions. They can be used to construct perfect lattice actions for asymptotically free fermionic theories like QCD or the Gross-Neveu model. The local fixed point actions for Wilson fermions break chiral symmetry, while in the staggered case the remnant $U(1)_e \\otimes U(1)_o$ symmetry is preserved. In addition, for Wilson fermions a nonlocal fixed point is found that corresponds to free chiral fermions. The vicinity of this fixed point is studied in the Gross-Neveu model using perturbation theory.
Path Integral Bosonization of Massive GNO Fermions
Park, Q H
1997-01-01
We show the quantum equivalence between certain symmetric space sine-Gordon models and the massive free fermions. In the massless limit, these fermions reduce to the free fermions introduced by Goddard, Nahm and Olive (GNO) in association with symmetric spaces $K/G$. A path integral formulation is given in terms of the Wess-Zumino-Witten action where the field variable $g$ takes value in the orthogonal, unitary, and symplectic representations of the group $G$ in the basis of the symmetric space. We show that, for example, such a path integral bosonization is possible when the symmetric spaces $K/G$ are $SU(N) the relation between massive GNO fermions and the nonabelian solitons, and explain the restriction imposed on the fermion mass matrix due to the integrability of the bosonic model.
Holographic strange metals, entanglement and fermion signs
Kaplis, N; Zaanen, J
2016-01-01
The fermion sign problem is often viewed as a sheer inconvenience that plagues numerical studies of strongly interacting electron systems. Only recently, it has been suggested that fermion signs are fundamental for the universal behavior of critical metallic systems and crucially enhance their degree of quantum entanglement. In this work we explore potential connections between emergent scale invariance of fermion sign structures and scaling properties of bipartite entanglement entropies. Our analysis is based on a wavefunction ansatz that incorporates collective, long-range backflow correlations into fermionic Slater determinants. Such wavefunctions mimic the collapse of a Fermi liquid at a quantum critical point. Their nodal surfaces -- a representation of the fermion sign structure in many-particle configurations space -- show fractal behavior up to a length scale $\\xi$ that diverges at a critical backflow strength. We show that the Hausdorff dimension of the fractal nodal surface depends on $\\xi$, the num...
Development of multiple laser frequency control system for Ca{sup +} isotope ion cooling
Energy Technology Data Exchange (ETDEWEB)
Jung, Kyunghun, E-mail: jung@lyman.q.t.u-tokyo.ac.jp [The University of Tokyo, Nuclear Professional School (Japan); Yamamoto, Yuta, E-mail: yamamoto@lyman.q.t.u-tokyo.ac.jp [The University of Tokyo, Department of Nuclear Engineering and Management (Japan); Hasegawa, Shuichi, E-mail: hasegawa@tokai.t.u-tokyo.ac.jp [The University of Tokyo, Nuclear Professional School (Japan)
2015-11-15
We here developed and evaluated a laser frequency control system which synchronizes the laser frequency to the resonance of target Ca {sup +} isotope ion whose having more than 8 GHz of isotope shift based on the Fringe Offset Lock method for simple operation of ICPMS-ILECS (Inductively Coupled Plasma Mass Spectrometry - Ion trap Laser Cooling Spectroscopy) The system fulfilled the minimum requirements of four slave lasers stability for Doppler cooling of Ca {sup +} ions. A performance of the system was evaluated by cooling {sup 40}Ca {sup +} ions with the stabilized slave lasers. All the stable even Ca {sup +} isotope ions were trapped and their fluorescence was observed by switching laser frequencies using the system. An odd calcium isotope {sup 43}Ca {sup +}cooling was also succeeded by the control system.
Observation of single Ca{sup +} ions for trace isotope analysis
Energy Technology Data Exchange (ETDEWEB)
Hashimoto, Y. [Department of Quantum Engineering and Systems Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)], E-mail: yhashi@lyman.q.t.u-tokyo.ac.jp; Matsuoka, L.; Nagamoto, D. [Department of Quantum Engineering and Systems Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Hasegawa, S. [Department of Quantum Engineering and Systems Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)], E-mail: hasegawa@q.t.u-tokyo.ac.jp
2008-06-15
We developed an ion trap - laser cooling system for observing the laser induced fluorescence (LIF) of a single ion, in the view of utilizing it for the trace isotope analysis of Ca. We observed stepwise LIF signals, which correspond to the numbers of trapped {sup 40}Ca{sup +} ions ({sup 40}Ca/Ca = 96.9%). The detection efficiency was evaluated and the observation of single ions demonstrated the experimental feasibility of trace isotope analysis. Furthermore, as the next step towards trace isotope analysis, we report observation of the even calcium isotopes, {sup 44}Ca ({sup 44}Ca/Ca = 2.09%) and {sup 48}Ca ({sup 48}Ca/Ca = 0.187%), without the use of a selective loading method.
Fermion Superfluidity And Confining Interactions
Galal, A A
2004-01-01
We study the pairing of Fermi systems with long-range, confining interparticle interactions. We solve the Cooper problem for a pair of fermions interacting via a regularized harmonic oscillator potential and determine the s-wave spectrum of bound states. Using a model of two interacting species of fermions, we calculate the ground state energy of the normal phase in the Hartree-Fock approximation and find that it is infrared (IR) divergent, due to a combination of the sharpness of the Fermi sea and the long-range nature of the interaction. We calculate the correlation energy in the normal phase using the random phase approximation (RPA) and demonstrate the cancellation of infrared divergences between the Hartree-Fock and RPA contributions. Introducing a variational wavefunction to study the superfluid phase, we solve the BCS equations using a Hartree-Fock-Bogoliubov (HFB) analysis to determine the wave-function, excitation gap, and other parameters of the superfluid phase. We show that the system crosses over...
Properties of Fermion Spherical Harmonics
Hunter, G; Hunter, Geoffrey; Emami-Razavi, Mohsen
2005-01-01
The Fermion Spherical harmonics [$Y_\\ell^{m}(\\theta,\\phi)$ for half-odd-integer $\\ell$ and $m$ - presented in a previous paper] are shown to have the same eigenfunction properties as the well-known Boson Spherical Harmonics [$Y_\\ell^{m}(\\theta,\\phi)$ for integer $\\ell$ and $m$]. The Fermion functions are shown to differ from the Boson functions in so far as the ladder operators $M_+$ ($M_-$) that ascend (descend) the sequence of harmonics over the values of $m$ for a given value of $\\ell$, do not produce the expected result {\\em in just one case}: when the value of $m$ changes from $\\pm{1/2}$ to $\\mp{1/2}$; i.e. when $m$ changes sign; in all other cases the ladder operators produce the usually expected result including anihilation when a ladder operator attempts to take $m$ outside the range: $-\\ell\\le m\\le +\\ell$. The unexpected result in the one case does not invalidate this scalar coordinate representation of spin angular momentum, because the eigenfunction property is essential for a valid quantum mechani...
Thermalization of Fermionic Quantum Walkers
Hamza, Eman; Joye, Alain
2017-03-01
We consider the discrete time dynamics of an ensemble of fermionic quantum walkers moving on a finite discrete sample, interacting with a reservoir of infinitely many quantum particles on the one dimensional lattice. The reservoir is given by a fermionic quasifree state, with free discrete dynamics given by the shift, whereas the free dynamics of the non-interacting quantum walkers in the sample is defined by means of a unitary matrix. The reservoir and the sample exchange particles at specific sites by a unitary coupling and we study the discrete dynamics of the coupled system defined by the iteration of the free discrete dynamics acting on the unitary coupling, in a variety of situations. In particular, in absence of correlation within the particles of the reservoir and under natural assumptions on the sample's dynamics, we prove that the one- and two-body reduced density matrices of the sample admit large times limits characterized by the state of the reservoir which are independent of the free dynamics of the quantum walkers and of the coupling strength. Moreover, the corresponding asymptotic density profile in the sample is flat and the correlations of number operators have no structure, a manifestation of thermalization.
Multiple Isotope Magneto Optical Trap from a single diode laser
Gomez, Eduardo; Valenzuela, Victor; Hamzeloui, Saeed; Gutierrez, Monica
2013-05-01
We present a simple design for a Dual Isotope Magneto Optical Trap. The system requires a single diode laser, a fiber modulator and a tapered amplifier to trap and completely control both 85Rb and 87Rb. We generate all the frequencies needed for trapping both species using the fiber intensity modulator. All the frequencies are amplified simultaneously with the tapered amplifier. The position and power of each frequency is now controlled independently on the RF rather than on the optical side. This introduces an enormous simplification for laser cooling that often requires an acousto-optic modulator for each frequency. The range of frequency changes is much bigger than what is available with acousto-optic modulators since in our case is determined by the modulator bandwidth (10 GHz). Additional isotopes can be simply added by including additional RF frequencies to the modulator and extra beams for other uses can be produced the same way. Support from CONACYT, PROMEP and UASLP.
Osaki, Kazuya; Okamoto, Hiromi
2014-05-01
S-LSR is a compact ion storage ring constructed at Kyoto University several years ago. The ring is equipped with a Doppler laser cooling system aimed at beam crystallization. Bearing in mind hardware limitations in S-LSR, we try to find an optimum set of primary experimental parameters for the production of an ultracold heavy ion beam. Systematic molecular dynamics simulations are carried out for this purpose. It is concluded that the detuning and spot size of the cooling laser should be chosen around -42 MHz and 1.5 mm, respectively, for the most efficient cooling of 40 keV ^{24}Mg^+ beams in S-LSR. Under the optimum conditions, the use of the resonant coupling method followed by radio-frequency field ramping enables us to reach an extremely low beam temperature on the order of 0.1 K in the transverse degrees of freedom. The longitudinal degree of freedom can be cooled to close to the Doppler limit; i.e., to the mK range. We also numerically demonstrate that it is possible to establish a stable, long one-dimensionally ordered state of ions.
Eismann, Ulrich; Salomon, Christophe; Chevy, Frédéric
2013-01-01
We present an all-solid-state laser source emitting up to 2.1 W of single-frequency light at 671 nm developed for laser cooling of lithium atoms. It is based on a diode-pumped, neodymium-doped orthovanadate (Nd:YVO$_4$) ring laser operating at 1342 nm. Optimization of the thermal management in the gain medium results in a maximum multi-frequency output power of 2.5 W at the fundamental wavelength. We develop a simple theory for the efficient implementation of intracavity second harmonic generation, and its application to our system allows us to obtain nonlinear conversion efficiencies of up to 88%. Single-mode operation and tuning is established by adding an etalon to the resonator. The second-harmonic wavelength can be tuned over 0.5 nm, and mode-hop-free scanning over more than 6 GHz is demonstrated, corresponding to around ten times the laser cavity free spectral range. The output frequency can be locked with respect to the lithium $D$-line transitions for atomic physics applications. Furthermore, we obser...
Hall, Felix H J; Hegi, Gregor; Raoult, Maurice; Aymar, Mireille; Dulieu, Olivier; Willitsch, Stefan
2013-01-01
Cold chemical reactions between laser-cooled Ca^+ ions and Rb atoms were studied in an ion-atom hybrid trap. Reaction rate constants were determined in the range of collision energies /k_B = 20 mK-20 K. The lowest energies were achieved in experiments using single localized Ca^+ ions. Product branching ratios were studied using resonant-excitation mass spectrometry. The dynamics of the reactive processes in this system (non-radiative and radiative charge transfer as well as radiative association leading to the formation of CaRb^+ molecular ions) have been analyzed using high-level quantum-chemical calculations of the potential energy curves of CaRb^+ and quantum-scattering calculations for the radiative channels. For the present low-energy scattering experiments, it is shown that the energy dependence of the reaction rate constants is governed by long-range interactions in line with the classical Langevin model, but their magnitude is determined by short-range non-adiabatic and radiative couplings which only ...
Eismann, U; Bergschneider, A; Sievers, F; Kretzschmar, N; Salomon, C; Chevy, F
2013-04-08
We present an all-solid-state laser source emitting up to 2.1 W of single-frequency light at 671 nm developed for laser cooling of lithium atoms. It is based on a diode-pumped, neodymium-doped orthovanadate (Nd:YVO(4)) ring laser operating at 1342 nm. Optimization of the thermal management in the gain medium results in a maximum multi-frequency output power of 2.5 W at the fundamental wavelength. We develop a simple theory for the efficient implementation of intracavity second harmonic generation, and its application to our system allows us to obtain nonlinear conversion efficiencies of up to 88%. Single-mode operation and tuning is established by adding an etalon to the resonator. The second-harmonic wavelength can be tuned over 0.5 nm, and mode-hop-free scanning over more than 6 GHz is demonstrated, corresponding to around ten times the laser cavity free spectral range. The output frequency can be locked with respect to the lithium D-line transitions for atomic physics applications. Furthermore, we observe parametric Kerr-lens mode-locking when detuning the phase-matching temperature sufficiently far from the optimum value.
Fermion Delocalization in Higgsless Models
De Curtis, S
2005-01-01
In the linear moose framework, which naturally emerges in deconstruction models, we discuss the effect of direct couplings between the left-handed fermions living on the boundary of the chain and the gauge fields in the internal sites. This is realized by means of a product of nonlinear sigma-model scalar fields which, in the continuum limit, is equivalent to a Wilson line. The effect of these new nonlocal couplings is a contribution to the S parameter which can be of opposite sign with respect to the one coming from the gauge fields along the string. Therefore, with some fine-tuning, it is possible to satisfy the constraints from the electro-weak data without spoiling the perturbative unitarity limit, which, in these models is generally postponed with respect to the Higgsless Standard Model one.
Chiral Dynamics With Wilson Fermions
Splittorff, K
2012-01-01
Close to the continuum the lattice spacing affects the smallest eigenvalues of the Wilson Dirac operator in a very specific manner determined by the way in which the discretization breaks chiral symmetry. These effects can be computed analytically by means of Wilson chiral perturbation theory and Wilson random matrix theory. A number of insights on chiral Dynamics with Wilson fermions can be obtained from the computation of the microscopic spectrum of the Wilson Dirac operator. For example, the unusual volume scaling of the smallest eigenvalues observed in lattice simulations has a natural explanation. The dynamics of the eigenvalues of the Wilson Dirac operator also allow us to determine the additional low energy constants of Wilson chiral perturbation theory and to understand why the Sharpe-Singleton scenario is only realized in unquenched simulations.
Noncommutativity Parameter and Composite Fermions
Jellal, Ahmed
We determine some particular values of the noncommutativity parameter θ and show that the Murthy Shankar approach is in fact a particular case of a more general one. Indeed, using the fractional quantum Hall effect (FQHE) experimental data, we give a measurement of θ. This measurement can be obtained by considering some values of the filling factor ν and other ingredients, magnetic field B and electron density ρ. Moreover, it is found that θ can be quantized either fractionally or integrally in terms of the magnetic length l0 and the quantization is exactly what Murthy and Shankar formulated recently for the FQHE. On the other hand, we show that the mapping of the FQHE in terms of the composite fermion basis has a noncommutative geometry nature and therefore there is a more general way than the Murthy Shankar method to do this mapping.
de Brito, K P S
2016-01-01
Spinor fields on 5-dimensional Lorentzian manifolds are classified, according to the geometric Fierz identities that involve their bilinear covariants. Based upon this classification that generalises the celebrated 4-dimensional Lounesto classification of spinor fields, new non-trivial classes of 5-dimensional spinor fields are, hence, found, with important potential applications regarding bulk fermions and their subsequent localisation on brane-worlds. In addition, quaternionic bilinear covariants are used to derive the quaternionic spin density, through the truncated exterior bundle. In order to accomplish a realisation of these new spinors, a Killing vector field is constructed on the horizon of 5-dimensional Kerr black holes. This Killing vector field is shown to reach the time-like Killing vector field at the spatial infinity, through a current 1-form density, constructed with the derived new spinor fields. The current density is, moreover, expressed as the f\\"unfbein components, assuming a condensed for...
de Brito, K. P. S.; da Rocha, Roldão
2016-10-01
The spinor fields on 5-dimensional Lorentzian manifolds are classified according to the geometric Fierz identities, which involve their bilinear covariants. Based upon this classification, which generalises the celebrated 4-dimensional Lounesto classification of spinor fields, new non-trivial classes of 5-dimensional spinor fields are hence found, with important potential applications regarding bulk fermions and their subsequent localisation on brane-worlds. In addition, quaternionic bilinear covariants are used to derive the quaternionic spin density through the truncated exterior bundle. In order to accomplish the realisation of these new spinors, a Killing vector field is constructed on the horizon of a 5-dimensional Kerr black hole. This Killing vector field is shown to reach the time-like Killing vector field at spatial infinity through a current 1-form density, constructed with the new derived spinor fields. The current density is, moreover, expressed as the fünfbein component, assuming a condensed form.
Flavor symmetries and fermion masses
Energy Technology Data Exchange (ETDEWEB)
Rasin, A.
1994-04-01
We introduce several ways in which approximate flavor symmetries act on fermions and which are consistent with observed fermion masses and mixings. Flavor changing interactions mediated by new scalars appear as a consequence of approximate flavor symmetries. We discuss the experimental limits on masses of the new scalars, and show that the masses can easily be of the order of weak scale. Some implications for neutrino physics are also discussed. Such flavor changing interactions would easily erase any primordial baryon asymmetry. We show that this situation can be saved by simply adding a new charged particle with its own asymmetry. The neutrality of the Universe, together with sphaleron processes, then ensures a survival of baryon asymmetry. Several topics on flavor structure of the supersymmetric grand unified theories are discussed. First, we show that the successful predictions for the Kobayashi-Maskawa mixing matrix elements, V{sub ub}/V{sub cb} = {radical}m{sub u}/m{sub c} and V{sub td}/V{sub ts} = {radical}m{sub d}/m{sub s}, are a consequence of a large class of models, rather than specific properties of a few models. Second, we discuss how the recent observation of the decay {beta} {yields} s{gamma} constrains the parameter space when the ratio of the vacuum expectation values of the two Higgs doublets, tan{Beta}, is large. Finally, we discuss the flavor structure of proton decay. We observe a surprising enhancement of the branching ratio for the muon mode in SO(10) models compared to the same mode in the SU(5) model.
Instantons and Massless Fermions in Two Dimensions
Callan, C. G. Jr.; Dashen, R.; Gross, D. J.
1977-05-01
The role of instantons in the breakdown of chiral U(N) symmetry is studied in a two dimensional model. Chiral U(1) is always destroyed by the axial vector anomaly. For N = 2 chiral SU(N) is also spontaneously broken yielding massive fermions and three (decoupled) Goldstone bosons. For N greater than or equal to 3 the fermions remain massless. Realistic four dimensional theories are believed to behave in a similar way but the critical N above which the fermions cease to be massive is not known in four dimensions.
Multigrid Algorithms for Domain-Wall Fermions
Cohen, Saul D; Clark, M A; Osborn, J C
2012-01-01
We describe an adaptive multigrid algorithm for solving inverses of the domain-wall fermion operator. Our multigrid algorithm uses an adaptive projection of near-null vectors of the domain-wall operator onto coarser four-dimensional lattices. This extension of multigrid techniques to a chiral fermion action will greatly reduce overall computation cost, and the elimination of the fifth dimension in the coarse space reduces the relative cost of using chiral fermions compared to discarding this symmetry. We demonstrate near-elimination of critical slowing as the quark mass is reduced and small volume dependence, which may be suppressed by taking advantage of the recursive nature of the algorithm.
Energy Technology Data Exchange (ETDEWEB)
Batra, Puneet; /Argonne; Dobrescu, Bogdan A.; /Fermilab; Spivak, David; /UC, Berkeley, Math. Dept.
2005-10-01
We present new techniques for finding anomaly-free sets of fermions. Although the anomaly cancellation conditions typically include cubic equations with integer variables that cannot be solved in general, we prove by construction that any chiral set of fermions can be embedded in a larger set of fermions which is chiral and anomaly-free. Applying these techniques to extensions of the Standard Model, we find anomaly-free models that have arbitrary quark and lepton charges under an additional U(1) gauge group.
Schwinger model simulations with dynamical overlap fermions
Bietenholz, W; Volkholz, J
2007-01-01
We present simulation results for the 2-flavour Schwinger model with dynamical overlap fermions. In particular we apply the overlap hypercube operator at seven light fermion masses. In each case we collect sizable statistics in the topological sectors 0 and 1. Since the chiral condensate Sigma vanishes in the chiral limit, we observe densities for the microscopic Dirac spectrum, which have not been addressed yet by Random Matrix Theory (RMT). Nevertheless, by confronting the averages of the lowest eigenvalues in different topological sectors with chiral RMT in unitary ensemble we obtain -- for the very light fermion masses -- values for $\\Sigma$ that follow closely the analytical predictions in the continuum.
Schwinger model simulations with dynamical overlap fermions
Energy Technology Data Exchange (ETDEWEB)
Bietenholz, W. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Shcheredin, S. [Bielefeld Univ. (Germany). Fakultaet fuer Physik; Volkholz, J. [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik
2007-11-15
We present simulation results for the 2-flavour Schwinger model with dynamical overlap fermions. In particular we apply the overlap hypercube operator at seven light fermion masses. In each case we collect sizable statistics in the topological sectors 0 and 1. Since the chiral condensate {sigma} vanishes in the chiral limit, we observe densities for the microscopic Dirac spectrum, which have not been addressed yet by Random Matrix Theory (RMT). Nevertheless, by confronting the averages of the lowest eigenvalues in different topological sectors with chiral RMT in unitary ensemble we obtain - for the very light fermion masses - values for {sigma} that follow closely the analytical predictions in the continuum. (orig.)
Grassmann phase space theory for fermions
Energy Technology Data Exchange (ETDEWEB)
Dalton, Bryan J. [Centre for Quantum and Optical Science, Swinburne University of Technology, Melbourne, Victoria, 3122 (Australia); Jeffers, John [Department of Physics, University of Strathclyde, Glasgow, G4 ONG (United Kingdom); Barnett, Stephen M. [School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ (United Kingdom)
2017-06-15
A phase space theory for fermions has been developed using Grassmann phase space variables which can be used in numerical calculations for cold Fermi gases and for large fermion numbers. Numerical calculations are feasible because Grassmann stochastic variables at later times are related linearly to such variables at earlier times via c-number stochastic quantities. A Grassmann field version has been developed making large fermion number applications possible. Applications are shown for few mode and field theory cases. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Batra, P; Spivak, D; Batra, Puneet; Dobrescu, Bogdan A.; Spivak, David
2006-01-01
We present new techniques for finding anomaly-free sets of fermions. Although the anomaly cancellation conditions typically include cubic equations with integer variables that cannot be solved in general, we prove by construction that any chiral set of fermions can be embedded in a larger set of fermions which is chiral and anomaly-free. Applying these techniques to extensions of the Standard Model, we find anomaly-free models that have arbitrary quark and lepton charges under an additional U(1) gauge group.
Fermionic bound states in distinct kinklike backgrounds
Energy Technology Data Exchange (ETDEWEB)
Bazeia, D. [Universidade Federal da Paraiba, Departamento de Fisica, Joao Pessoa, Paraiba (Brazil); Mohammadi, A. [Universidade Federal de Campina Grande, Departamento de Fisica, Caixa Postal 10071, Campina Grande, Paraiba (Brazil)
2017-04-15
This work deals with fermions in the background of distinct localized structures in the two-dimensional spacetime. Although the structures have a similar topological character, which is responsible for the appearance of fractionally charged excitations, we want to investigate how the geometric deformations that appear in the localized structures contribute to the change in the physical properties of the fermionic bound states. We investigate the two-kink and compact kinklike backgrounds, and we consider two distinct boson-fermion interactions, one motivated by supersymmetry and the other described by the standard Yukawa coupling. (orig.)
Elias, V; Elias, Victor; Sprague, Kevin
1998-01-01
We consider the contribution of fermion-antifermion condensates to the anomalous magnetic moment of a fermion in a vacuum in which such condensates exist. The real part of the condensate contribution to the anomalous magnetic moment is shown to be zero. A nonzero imaginary part is obtained below the kinematic threshold for intermediate fermion-antifermion pairs. The calculation is shown to be gauge-parameter independent provided a single fermion mass characterizes both the fermion propagator and condensate-sensitive contributions, suggestive of a dynamically-generated fermion mass. The nonzero imaginary part is then argued to correspond to the kinematic production of the intermediate-state Goldstone bosons anticipated from a chiral-noninvariant vacuum. Finally, speculations are presented concerning the applicability of these results to quark electromagnetic properties.
Ideal Fermion Delocalization in Higgsless Models
Chivukula, R S; Kurachi, M; Simmons, E H; Tanabashi, M; He, Hong-Jian; Kurachi, Masafumi; Simmons, Elizabeth H.; Tanabashi, Masaharu
2005-01-01
In this note we examine the properties of deconstructed Higgsless models for the case of a fermion whose SU(2) properties arise from delocalization over many sites of the deconstructed lattice. We derive expressions for the correlation functions and use these to establish a generalized consistency relation among correlation functions. We discuss the form of the W boson wavefunction and show that if the probability distribution of the delocalized fermions is appropriately related to the W wavefunction, then deviations in precision electroweak parameters are minimized. In particular, we show that this "ideal fermion delocalization" results in the vanishing of three of the four leading zero-momentum electroweak parameters defined by Barbieri, et. al. We then discuss ideal fermion delocalization in the context of two continuum Higgsless models, one in Anti-deSitter space and one in flat space. Our results may be applied to any Higgsless linear moose model with multiple SU(2) groups, including those with only a fe...
Thermostatistics of bosonic and fermionic Fibonacci oscillators
Algin, Abdullah; Arik, Metin; Senay, Mustafa; Topcu, Gozde
2017-01-01
In this work, we first introduce some new properties concerning the Fibonacci calculus. We then discuss the thermostatistics of gas models of two-parameter deformed oscillators, called bosonic and fermionic Fibonacci oscillators, in the thermodynamical limit. In this framework, we analyze the behavior of two-parameter deformed mean occupation numbers describing the Fibonacci-type bosonic and fermionic intermediate-statistics particles. A virial expansion of the equation of state for the bosonic Fibonacci oscillators’ gas model is obtained in both two and three dimensions, and the first five virial coefficients are derived in terms of the real independent deformation parameters p and q. The effect of bosonic and fermionic p, q-deformation on the thermostatistical properties of Fibonacci-type p, q-boson and p, q-fermion gas models are also discussed. The results obtained in this work can be useful for investigating some exotic quasiparticle states encountered in condensed matter systems.
Chiral fermions in asymptotically safe quantum gravity
Energy Technology Data Exchange (ETDEWEB)
Meibohm, J. [Gothenburg University, Department of Physics, Goeteborg (Sweden); Universitaet Heidelberg, Institut fuer Theoretische Physik, Heidelberg (Germany); Pawlowski, J.M. [Universitaet Heidelberg, Institut fuer Theoretische Physik, Heidelberg (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung mbH, ExtreMe Matter Institute EMMI, Darmstadt (Germany)
2016-05-15
We study the consistency of dynamical fermionic matter with the asymptotic safety scenario of quantum gravity using the functional renormalisation group. Since this scenario suggests strongly coupled quantum gravity in the UV, one expects gravity-induced fermion self-interactions at energies of the Planck scale. These could lead to chiral symmetry breaking at very high energies and thus to large fermion masses in the IR. The present analysis which is based on the previous works (Christiansen et al., Phys Rev D 92:121501, 2015; Meibohm et al., Phys Rev D 93:084035, 2016), concludes that gravity-induced chiral symmetry breaking at the Planck scale is avoided for a general class of NJL-type models. We find strong evidence that this feature is independent of the number of fermion fields. This finding suggests that the phase diagram for these models is topologically stable under the influence of gravitational interactions. (orig.)
Fully antisymmetrised dynamics for bulk fermion systems
Vantournhout, Klaas
2011-01-01
The neutron star's crust and mantel are typical examples of non-uniform bulk systems with spacial localisations. When modelling such systems at low temperatures, as is the case in the crust, one has to work with antisymmetrised many-body states to get the correct fermion behaviour. Fermionic molecular dynamics, which works with an antisymmetrised product of localised wave packets, should be an appropriate choice. Implementing periodic boundary conditions into the fermionic molecular dynamics formalism would allow the study of the neutron star's crust as a bulk quantum system. Unfortunately, the antisymmetrisation is a non-local entanglement which reaches far out of the periodically repeated unit cell. In this proceeding, we give a brief overview how periodic boundary conditions and fermionic molecular dynamics can be combined without truncating the long-range many-body correlation induced by the antisymmetry of the many-body state.
Chiral fermions in asymptotically safe quantum gravity
Meibohm, Jan
2016-01-01
We study the consistency of dynamical fermionic matter with the asymptotic safety scenario of quantum gravity using the functional renormalisation group. Since this scenario suggests strongly coupled quantum gravity in the UV, one expects gravity-induced fermion self-interactions at energies of the Planck-scale. These could lead to chiral symmetry breaking at very high energies and thus to large fermion masses in the IR. The present analysis which is based on the previous works \\cite{Christiansen:2015rva, Meibohm:2015twa}, concludes that gravity-induced chiral symmetry breaking at the Planck scale is avoided for a general class of NJL-type models, regardless of the number of fermion flavours. This suggests that the phase diagram for these models is topologically stable under the influence of gravitational interactions.
Amplified Fermion Production from Overpopulated Bose Fields
Berges, J; Sexty, D
2014-01-01
We study the real-time dynamics of fermions coupled to scalar fields in a linear sigma model, which is often employed in the context of preheating after inflation or as a low-energy effective model for quantum chromodynamics. We find a dramatic amplification of fermion production in the presence of highly occupied bosonic quanta for weak as well as strong couplings. For this we consider the range of validity of different methods: lattice simulations with male/female fermions, the mode functions approach and the quantum 2PI effective action with its associated kinetic theory. For strongly coupled fermions we find a rapid approach to a Fermi-Dirac distribution with time-dependent temperature and chemical potential parameters, while the bosons are still far from equilibrium.
Fermionic orbital optimisation in tensor network states
Krumnow, C; Eisert, J
2015-01-01
Tensor network states and specifically matrix-product states have proven to be a powerful tool for simulating ground states of strongly correlated spin models. Recently, they have also been applied to interacting fermionic problems, specifically in the context of quantum chemistry. A new freedom arising in such non-local fermionic systems is the choice of orbitals, it being far from clear what choice of fermionic orbitals to make. In this work, we propose a way to overcome this challenge. We suggest a method intertwining the optimisation over matrix product states with suitable fermionic Gaussian mode transformations, hence bringing the advantages of both approaches together. The described algorithm generalises basis changes in the spirit of the Hartree-Fock methods to matrix-product states, and provides a black box tool for basis optimisations in tensor network methods.
The principle of the Fermionic projector
Finster, Felix
2006-01-01
The "principle of the fermionic projector" provides a new mathematical framework for the formulation of physical theories and is a promising approach for physics beyond the standard model. This book begins with a brief review of relativity, relativistic quantum mechanics, and classical gauge theories, emphasizing the basic physical concepts and mathematical foundations. The external field problem and Klein's paradox are discussed and then resolved by introducing the fermionic projector, a global object in space-time that generalizes the notion of the Dirac sea. At the mathematical core of the book is a precise definition of the fermionic projector and the use of methods of hyperbolic differential equations for detailed analysis. The fermionic projector makes it possible to formulate a new type of variational principle in space-time. The mathematical tools are developed for the analysis of the corresponding Euler-Lagrange equations. A particular variational principle is proposed that gives rise to an effective...
Generalized Gravitational Entropy from Fermion Fields
Huang, Wung-Hong
2016-01-01
The generalized gravitational entropy proposed in recent by Lewkowycz and Maldacena [1] is extended to the system of Fermion fields. We first find the regular wave solution of Fermion field which has arbitrary frequency and mode number on the BTZ spacetime, and then use it to calculate the exact gravitational entropy. The results show that there is a threshold frequency below which the Fermion fields could not contribute the generalized gravitational entropy. Also, the static and zero-mode solutions have not entropy, contrast to that in scalar field. We also found that the entropy of the static scalar fields and non-static fermions is an increasing function of mode number and, after arriving the maximum entropy it becomes a deceasing function and is derived to the asymptotic value.
Nonequilibrium fermion production in quantum field theory
Energy Technology Data Exchange (ETDEWEB)
Pruschke, Jens
2010-06-16
The creation of matter in the early universe or in relativistic heavy-ion collisions is inevitable connected to nonequilibrium physics. One of the key challenges is the explanation of the corresponding thermalization process following nonequilibrium instabilities. The role of fermionic quantum fields in such scenarios is discussed in the literature by using approximations of field theories which neglect important quantum corrections. This thesis goes beyond such approximations. A quantum field theory where scalar bosons interact with Dirac fermions via a Yukawa coupling is analyzed in the 2PI effective action formalism. The chosen approximation allows for a correct description of the dynamics including nonequilibrium instabilities. In particular, fermion-boson loop corrections allow to study the interaction of fermions with large boson fluctuations. The applied initial conditions generate nonequilibrium instabilities like parametric resonance or spinodal instabilities. The equations of motion for correlation functions are solved numerically and major characteristics of the fermion dynamics are described by analytical solutions. New mechanisms for the production of fermions are found. Simulations in the case of spinodal instability show that unstable boson fluctuations induce exponentially growing fermion modes with approximately the same growth rate. If the unstable regime lasts long enough a thermalization of the infrared part of the fermion occupation number occurs on time scales much shorter than the time scale on which bosonic quantum fields thermalize. Fermions acquire an excess of occupation in the ultraviolet regime compared to a Fermi-Dirac statistic characterized by a power-law with exponent two. The fermion production mechanism via parametric resonance is found to be most efficient after the instability ends. Quantum corrections then provide a very efficient particle creation mechanism which is interpreted as an amplification of decay processes. The ratio
Fermionic cosmologies with Yukawa type interactions
Ribas, Marlos O; Kremer, Gilberto M
2010-01-01
In this work we discuss if fermionic sources could be responsible for accelerated periods in a Friedmann-Robertson-Walker spatially flat universe, including a usual self-interaction potential of the Nambu-Jona-Lasinio type together with a fermion-scalar interaction potential of the Yukawa type. The results show that the combination of these potentials could promote an initially accelerated period, going through a middle decelerated era, with a final eternal accelerated period, where the self-interaction contribution dominates.
Fermions in a Walecka-type cosmology
Ribas, Marlos O; Devecchi, Fernando P; Kremer, Gilberto M
2012-01-01
A simplified Walecka-type model is investigated in a cosmological scenario. The model includes fermionic, scalar and vector fields as sources. It is shown that their interactions, taking place in a Robertson-Walker metric, could be responsible for the transition of accelerated-decelerated periods in the early universe and a current accelerated regime. It is also discussed the role of the fermionic field as the promoter of the accelerated regimes in the early and the late stages of the universe.
Fermions in Brans-Dicke cosmology
Samojeden, L L; Kremer, G M
2010-01-01
Using the Brans-Dicke theory of gravitation we put under investigation a hypothetical universe filled with a fermionic field (with a self interaction potential) and a matter constituent ruled by a barotropic equation of state. It is shown that the fermionic field (in combination with the Brans-Dicke scalar field could be responsible for a final accelerated era, after an initial matter dominated period.
Dynamical fermion mass hierarchy and flavour mixing
Energy Technology Data Exchange (ETDEWEB)
Luest, D.; Papantonopoulos, E.; Zoupanos, G.
1984-08-01
The chiral symmetry breaking of high colour representations produces dynamical breaking of the standard electroweak gauge symmetry. By enlarging the colour group and subsequently breaking it down to SU(3)sub(c) fermions acquire radiative masses from the chiral breaking. We present attempts to produce realistic fermion mass matrix in two classes of models depending on the way that the colour group is enlarged. A realistic example is found in one of these classes of models.
Dilaton and dynamical fermion mass generation
Energy Technology Data Exchange (ETDEWEB)
Hung, P.Q.; Zoupanos, G.
1987-05-21
In gauge theories with a hierarchy of mass scales there might appear a pseudo-Goldstone boson, the dilaton, resulting from the spontaneous breaking of scale symmetry. In addition light pseudoscalar bosons (axions) are expected in this class of models. We show that dynamical generation of fermion masses in these theories and the existence of a dilaton lead to unacceptably high axion masses. Therefore a dynamical fermion mass generation mechanism and a dilaton cannot coexist in a large class of such gauge theories.
Majorana Fermions and Topology in Superconductors
Sato, Masatoshi; Fujimoto, Satoshi
2016-01-01
Topological superconductors are novel classes of quantum condensed phases, characterized by topologically nontrivial structures of Cooper pairing states. On the surfaces of samples and in vortex cores of topological superconductors, Majorana fermions, which are particles identified with their own anti-particles, appear as Bogoliubov quasiparticles. The existence and stability of Majorana fermions are ensured by bulk topological invariants constrained by the symmetries of the systems. Majorana...
Universality and ambiguity in fermionic effective actions
de Berredo-Peixoto, Guilherme; Shapiro, Ilya L
2012-01-01
We discuss an ambiguity in the one-loop effective action of massive fields which takes place in massive fermionic theories. The universality of logarithmic UV divergences in different space-time dimensions leads to the non-universality of the finite part of effective action, which can be called the non-local multiplicative anomaly. The general criteria of existence of this phenomena are formulated and applied to fermionic operators with different external fields.
Evolution of boson-fermion stars
Valdez-Alvarado, Susana; Palenzuela, Carlos; Alic, Daniela; Ureña-López, L. Arturo; Becerril, Ricardo
2012-08-01
The boson-fermion stars can be modeled with a complex scalar field coupled minimally to a perfect fluid (i.e., without viscosity and non-dissipative). We present a study of these solutions and their dynamical evolution by solving numerically the Einstein-Klein-Gordon-Hydrodynamic (EKGHD) system. It is shown that stable configurations exist, but stability of general configurations depends finely upon the number of bosons and fermions.
Superfluid response in heavy fermion superconductors
Zhong, Yin; Zhang, Lan; Shao, Can; Luo, Hong-Gang
2017-10-01
Motivated by a recent London penetration depth measurement [H. Kim, et al., Phys. Rev. Lett. 114, 027003 (2015)] and novel composite pairing scenario [O. Erten, R. Flint, and P. Coleman, Phys. Rev. Lett. 114, 027002 (2015)] of the Yb-doped heavy fermion superconductor CeCoIn5, we revisit the issue of superfluid response in the microscopic heavy fermion lattice model. However, from the literature, an explicit expression for the superfluid response function in heavy fermion superconductors is rare. In this paper, we investigate the superfluid density response function in the celebrated Kondo-Heisenberg model. To be specific, we derive the corresponding formalism from an effective fermionic large- N mean-field pairing Hamiltonian whose pairing interaction is assumed to originate from the effective local antiferromagnetic exchange interaction. Interestingly, we find that the physically correct, temperature-dependent superfluid density formula can only be obtained if the external electromagnetic field is directly coupled to the heavy fermion quasi-particle rather than the bare conduction electron or local moment. Such a unique feature emphasizes the key role of the Kondo-screening-renormalized heavy quasi-particle for low-temperature/energy thermodynamics and transport behaviors. As an important application, the theoretical result is compared to an experimental measurement in heavy fermion superconductors CeCoIn5 and Yb-doped Ce1- x Yb x CoIn5 with fairly good agreement and the transition of the pairing symmetry in the latter material is explained as a simple doping effect. In addition, the requisite formalism for the commonly encountered nonmagnetic impurity and non-local electrodynamic effect are developed. Inspired by the success in explaining classic 115-series heavy fermion superconductors, we expect the present theory will be applied to understand other heavy fermion superconductors such as CeCu2Si2 and more generic multi-band superconductors.
A special fermionic generalization of lineal gravity
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
The central extension of the (1+1)-dimensional Poincaré algebra by including fermionic charges which obey not supersymmetric algebra, but a special graded algebra containing in the right hand side a central element only is obtained. The corresponding theory being the fermionic extension of the lineal gravity is proposed. We considered the algebra of generators, the field transformations and found Lagrangian and equation of motion, then we derived the Casimir operator and obtained the constant black hole mass.
Dual of QCD with One Adjoint Fermion
Mojaza, Matin; Pica, Claudio; Sannino, Francesco
2011-01-01
We construct the magnetic dual of QCD with one adjoint Weyl fermion. The dual is a consistent solution of the 't Hooft anomaly matching conditions, allows for flavor decoupling and remarkably constitutes the first nonsupersymmetric dual valid for any number of colors. The dual allows to bound the anomalous dimension of the Dirac fermion mass operator to be less than one in the conformal window.
Quantum Gas Microscope for Fermionic Atoms
Okan, Melih; Cheuk, Lawrence; Nichols, Matthew; Lawrence, Katherine; Zhang, Hao; Zwierlein, Martin
2016-05-01
Strongly interacting fermions define the properties of complex matter throughout nature, from atomic nuclei and modern solid state materials to neutron stars. Ultracold atomic Fermi gases have emerged as a pristine platform for the study of many-fermion systems. In this poster we demonstrate the realization of a quantum gas microscope for fermionic 40 K atoms trapped in an optical lattice and the recent experiments which allows one to probe strongly correlated fermions at the single atom level. We combine 3D Raman sideband cooling with high- resolution optics to simultaneously cool and image individual atoms with single lattice site resolution at a detection fidelity above 95%. The imaging process leaves the atoms predominantly in the 3D motional ground state of their respective lattice sites, inviting the implementation of a Maxwell's demon to assemble low-entropy many-body states. Single-site resolved imaging of fermions enables the direct observation of magnetic order, time resolved measurements of the spread of particle correlations, and the detection of many-fermion entanglement. NSF, AFOSR-PECASE, AFOSR-MURI on Exotic Phases of Matter, ARO-MURI on Atomtronics, ONR, a Grant from the Army Research Office with funding from the DARPA OLE program, and the David and Lucile Packard Foundation.
Lattice theory of nonequilibrium fermion production
Energy Technology Data Exchange (ETDEWEB)
Gelfand, Daniil
2014-07-22
In this thesis we investigate non-equilibrium production of fermionic particles using modern lattice techniques. The presented applications range from preheating after inflation in the early Universe cosmology to pre-thermalization dynamics in heavy-ion collisions as well as pair production and string breaking in a lower-dimensional model of quantum chromodynamics. Strong enhancement of fermion production in the presence of overoccupied bosons is observed in scalar models undergoing instabilities. Both parametric resonance and tachyonic instability are considered as scenarios for preheating after inflation. The qualitative and quantitative features of the resulting fermion distribution are found to depend largely on an effective coupling parameter. In order to simulate fermions in three spatial dimensions we apply a stochastic low-cost lattice algorithm, which we verify by comparison with an exact lattice approach and with a functional method based on a coupling expansion. In the massive Schwinger model, we analyse the creation of fermion/anti-fermion pairs from homogeneous and inhomogeneous electric fields and observe string formation between charges. As a follow-up we study the dynamics of string breaking and establish a two-stage process, consisting of the initial particle production followed by subsequent charge separation and screening. In quantum chromodynamics, our focus lies on the properties of the quark sector during turbulent bosonic energy cascade as well as on the isotropization of quarks and gluons starting from different initial conditions.
Fermion-induced quantum critical points.
Li, Zi-Xiang; Jiang, Yi-Fan; Jian, Shao-Kai; Yao, Hong
2017-08-22
A unified theory of quantum critical points beyond the conventional Landau-Ginzburg-Wilson paradigm remains unknown. According to Landau cubic criterion, phase transitions should be first-order when cubic terms of order parameters are allowed by symmetry in the Landau-Ginzburg free energy. Here, from renormalization group analysis, we show that second-order quantum phase transitions can occur at such putatively first-order transitions in interacting two-dimensional Dirac semimetals. As such type of Landau-forbidden quantum critical points are induced by gapless fermions, we call them fermion-induced quantum critical points. We further introduce a microscopic model of SU(N) fermions on the honeycomb lattice featuring a transition between Dirac semimetals and Kekule valence bond solids. Remarkably, our large-scale sign-problem-free Majorana quantum Monte Carlo simulations show convincing evidences of a fermion-induced quantum critical points for N = 2, 3, 4, 5 and 6, consistent with the renormalization group analysis. We finally discuss possible experimental realizations of the fermion-induced quantum critical points in graphene and graphene-like materials.Quantum phase transitions are governed by Landau-Ginzburg theory and the exceptions are rare. Here, Li et al. propose a type of Landau-forbidden quantum critical points induced by gapless fermions in two-dimensional Dirac semimetals.
Neutrinos Are Nearly Dirac Fermions
Cahill, K E
1999-01-01
Neutrino masses and mixings are analyzed in terms of left-handed fields and a 6x6 complex symmetric mass matrix whose singular values are the neutrino masses. An angle theta_nu characterizes the kind of the neutrinos, with theta_nu = 0 for Dirac neutrinos and theta_nu = pi/2 for Majorana neutrinos. If theta_nu = 0, then baryon-minus-lepton number is conserved. When theta_nu is approximately zero, the six neutrino masses coalesce into three nearly degenerate pairs. Thus the smallness of the differences in neutrino masses exhibited in the solar and atmospheric neutrino experiments and the stringent limits on neutrinoless double-beta decay are naturally explained if B-L is approximately conserved and neutrinos are nearly Dirac fermions. If one sets theta_nu = 0.0005, suppresses inter-generational mixing, and imposes a quark-like mass hierarchy, then one may fit the essential features of the solar, reactor, and atmospheric neutrino experiments with otherwise random mass matrices in the eV range. This B-L model le...
Suggestions on photons and fermions
Alvargonzalez, R
2007-01-01
In this paper we suggest a configuration of photons consistent with a spin $\\hbar$, and a configuration of the fermions coherent with a spin $\\hbar/2$. These suggested configurations open the way to further analyses which lead to the following conclusions: - There cannot exist elementary particles of spin $\\hbar/2$ with a mass inferior to $1m_e$ or with a radius greater than $1l_e$. - The electrostatic force derives from the centrifugal forces inherent to the spin and are propagated by photons. - The derivation of the electrostatic force explains the existence of positive and negative charges and Coulomb's law. - The enormous differences between the centrifugal forces and the centripetal forces at the surface of the protons give rise to quantic fluctuations of space which generate the energy flows necessary for equilibrium. These energy flows can explain gravitation and the strong force. - The mass of the proton, $m_p$, and the mass of the neutron, $m_n$, must each have a concrete value required for the cohes...
Das, Joy Prakash; Setlur, Girish S.
2017-10-01
The one step fermionic ladder refers to two parallel Luttinger Liquids (poles of the ladder) placed such that there is a finite probability of electrons hopping between the two poles at a pair of opposing points along each of the poles. The many-body Green function for such a system is calculated in presence of forward scattering interactions using the powerful non-chiral bosonization technique (NCBT). This technique is based on a non-standard harmonic analysis of the rapidly varying parts of the density fields appropriate for the study of strongly inhomogeneous ladder systems. The closed analytical expression for the correlation function obtained from NCBT is nothing but the series involving the RPA (Random Phase Approximation) diagrams in powers of the forward scattering coupling strength resummed to include only the most singular terms with the source of inhomogeneities treated exactly. Finally the correlation functions are used to study physical phenomena such as Friedel oscillations and the conductance of such systems with the potential difference applied across various ends.
Iterants, Fermions and Majorana Operators
Kauffman, Louis H.
Beginning with an elementary, oscillatory discrete dynamical system associated with the square root of minus one, we study both the foundations of mathematics and physics. Position and momentum do not commute in our discrete physics. Their commutator is related to the diffusion constant for a Brownian process and to the Heisenberg commutator in quantum mechanics. We take John Wheeler's idea of It from Bit as an essential clue and we rework the structure of that bit to a logical particle that is its own anti-particle, a logical Marjorana particle. This is our key example of the amphibian nature of mathematics and the external world. We show how the dynamical system for the square root of minus one is essentially the dynamics of a distinction whose self-reference leads to both the fusion algebra and the operator algebra for the Majorana Fermion. In the course of this, we develop an iterant algebra that supports all of matrix algebra and we end the essay with a discussion of the Dirac equation based on these principles.
Sextet Model with Wilson Fermions
Hansen, Martin
2016-01-01
We present new results from our ongoing study of the SU(3) sextet model with two flavors in the two-index symmetric representation of the gauge group. In the simulations use unimproved Wilson fermions to investigate the infrared properties of the model. We have previously presented results for the spectrum of the model in the weak coupling regime. Here, to better understand the overall behavior of the lattice model, we map its non-trivial phase structure in the space of bare parameters. At strong coupling, we observe a first order phase transition when decreasing the bare quark mass. This first order transition weakens when moving towards weaker couplings with an endpoint at a finite value of the bare coupling, after which it appears to be a continuous transition. We also investigate the behavior of the mass spectrum and scale-setting observable, as a function of the quark mass, and show that their qualitative behavior change significantly when moving from the strong coupling into the weak coupling phase.
Adams, David H
2008-01-01
To investigate the viability of the 4th root trick for the staggered fermion determinant in a simpler setting, we consider a two taste (flavor) lattice fermion formulation with no taste mixing but with exact taste-nonsinglet chiral symmetries analogous to the taste-nonsinglet $U(1)_A$ symmetry of staggered fermions. Creutz's objections to the rooting trick apply just as much in this setting. To counter them we show that the formulation has robust would-be zero-modes in topologically nontrivial gauge backgrounds, and that these manifest themselves in a viable way in the rooted fermion determinant and also in the disconnected piece of the pseudoscalar meson propagator as required to solve the U(1) problem. Also, our rooted theory is seen to be in the right universality class for QCD if the same is true for an unrooted mixed fermion action theory.
Time reversal, fermion doubling, and the masses of lattice Dirac fermions in three dimensions
Herbut, Igor F.
2011-06-01
Motivated by recent examples of three-dimensional lattice Hamiltonians with massless Dirac fermions in their (bulk) spectrum, I revisit the problem of fermion doubling on bipartite lattices. The number of components of the Dirac fermion in a time-reversal and parity-invariant d-dimensional lattice system is determined by the minimal representation of the Clifford algebra of d+1 Hermitian Dirac matrices that allows a construction of the time-reversal operator with the square of unity, and it equals 2d for d=2 and 3. Possible mass terms for (spinless) Dirac fermions are listed and discussed. In three dimensions, there are altogether eight independent masses, out of which four are even and four are odd under time reversal. A specific violation of time-reversal symmetry that leads to (minimal) four-component massless Dirac fermion in three dimensions at low energies is constructed.
Proposal of Unified Fermion Texture
Krolikowski, W.
1998-03-01
unified form of mass matrix is proposed for neutrinos, charged leptons, up quarks and down quarks. Some constraints for the parameters involved are tentatively postulated. Then, the predictions are neatly consistent with available experimental data. Among the predictions are: (i) mτ ~1776.80 MeV (with the inputs of me and mμ ), (ii) mν_0 ≪ mν_1~(0.6 to )× 10-2 eV and mν_2~ (0.2 to 1)× 10-1 eV (with the atmospheric-neutrino inputs of |mν_22 - mν_12| × (0.0003 to 0.01) eV2 and the νμ → ντ oscillation amplitude × 0.8), and also ( iii) ms ~270 MeV, |Vub/Vcb| ~0.082 and argVub ~-640 (with the inputs of mc = 1.3 GeV, mb = 4.5 GeV, |Vus| = 0.221 and |Vcb| = 0.041, where mu ≪ mc ≪ mt and md ≪ ms ≪ mb ). All elements of the Cabibbo--Kobayashi--Maskawa matrix are evaluated. All elements of its lepton counterpart are calculated up to an unknown phase (Appendix B). Some items related to dynamical aspects of the proposed fermion ``texture'' are briefly commented on (Appendix A). In particular, the notion of a novel dark matter, free of any Standard Model interactions (and their supersymmetric variants), appears in the case of preon option.
Ambiguities and Subtleties in Fermion Mass Terms
Cheng, Yifan
2013-01-01
This is a review on structure of the fermion mass terms of the Standard Model extended with the so-called "right-handed neutrinos" or "sterile neutrinos". The review is meant to be pedagogical, with detailed mathematics presented beyond the level one can find any easily in the literature. The discussions, however, bring up important subtleties and ambiguities about the subject that may be less than well appreciated. In fact, the naive perspective of the nature and masses of fermions as one would easily drawn from the presentations of fermion fields and their equations of motion from a typical textbook on quantum field theory leads to some confusing or even wrong statements which we clarify here. In particular, we illustrate clearly that a Dirac fermion mass eigenstate is mathematically equivalent to two degenerated Majorana fermion mass eigenstates at least so long as the mass terms are concerned. There are further ambiguities and subtleties in the exact description of the eigenstate(s). For the case of the n...
Mass Spectrum of Fermion on Bloch Branes with New Scalar-fermion Coupling
Xie, Qun-Ying; Zhao, Zhen-Hua; Du, Yun-Zhi; Zhang, Yu-Peng
2015-01-01
In order to localize a left- or right-handed fermion zero mode on a thick brane, one usually introduces the Yukawa coupling $\\eta \\bar{\\Psi} F(\\chi) \\Psi$ between a bulk fermion and the background scalar field $\\chi$. However, the Yukawa coupling will do not work if the background scalar is an even function of the extra dimension. Recently, Ref. [Phy. Rev. \\textbf{D} 89 (2014) 086001] has presented a new scalar-fermion coupling form $\\lambda \\bar \\Psi \\Gamma^M \\partial_M F(\\chi) \\gamma^5 \\Psi$ in order to deal with this problem. In this paper, we investigate the localization and mass spectrum of fermion on the Bloch brane by using the new scalar-fermion coupling with $F(\\chi)=\\chi^n$. It is found that the effective potentials have rich structure and may be volcano-like, finite square well-like, and infinite potentials, which depend on the parameter $n$. As a result, there may appear some resonant KK fermions, finite or infinite numbers of bound KK fermions.
Symmetries of Ginsparg-Wilson Chiral Fermions
Mandula, Jeffrey E
2009-01-01
The group structure of the variant chiral symmetry discovered by Luscher in the Ginsparg-Wilson description of lattice chiral fermions is analyzed. It is shown that the group contains an infinite number of linearly independent symmetry generators, and the Lie algebra is given explicitly. CP is an automorphism of this extended chiral group, and the CP transformation properties of the symmetry generators are found. The group has an infinite-parameter subgroup, and the factor group whose elements are its cosets is isomorphic to the continuum chiral symmetry group. Features of the currents associated with these symmetries are discussed, including the fact that some different, non-commuting symmetry generators lead to the same Noether current. These are universal features of lattice chiral fermions based on the Ginsparg-Wilson relation; they occur in the overlap, domain-wall, and perfect-action formulations. In a solvable example - free overlap fermions - these non-canonical elements of lattice chiral symmetry are...
Heavy Dynamical Fermions in Lattice QCD
Hasenfratz, Anna; Hasenfratz, Anna; Grand, Thomas A. De
1994-01-01
It is expected that the only effect of heavy dynamical fermions in QCD is to renormalize the gauge coupling. We derive a simple expression for the shift in the gauge coupling induced by $N_f$ flavors of heavy fermions. We compare this formula to the shift in the gauge coupling at which the confinement-deconfinement phase transition occurs (at fixed lattice size) from numerical simulations as a function of quark mass and $N_f$. We find remarkable agreement with our expression down to a fairly light quark mass. However, simulations with eight heavy flavors and two light flavors show that the eight flavors do more than just shift the gauge coupling. We observe confinement-deconfinement transitions at $\\beta=0$ induced by a large number of heavy quarks. We comment on the relevance of our results to contemporary simulations of QCD which include dynamical fermions.
Quark Seesaw Vectorlike Fermions and Diphoton Excess
Dev, P S Bhupal; Zhang, Yongchao
2015-01-01
We present a possible interpretation of the recent diphoton excess reported by the $\\sqrt s=13$ TeV LHC data in quark seesaw left-right models with vectorlike fermions proposed to solve the strong $CP$ problem without the axion. The gauge singlet real scalar field responsible for the mass of the vectorlike fermions has the right production cross section and diphoton branching ratio to be identifiable with the reported excess at around 750 GeV diphoton invariant mass. Various ways to test this hypothesis as more data accumulates at the LHC are proposed. In particular, we find that for our interpretation to work, there is an upper limit on the right-handed scale $v_R$, which depends on the Yukawa coupling of singlet Higgs field to the vectorlike fermions.
Vacuum polarization and chiral lattice fermions
Randjbar-Daemi, S.; Strathdee, J.
1996-02-01
The vacuum polarization due to chiral fermions on a 4-dimensional Euclidean lattice is calculated according to the overlap prescription. The fermions are coupled to weak and slowly varying background gauge and Higgs fields, and the polarization tensor is given by second order perturbation theory. In this order the overlap constitutes a gauge-invariant regularization of the fermion vacuum amplitude. Its low-energy-long-wavelength behaviour can be computed explicitly and we verify that it coincides with the Feynman graph result obtainable, for example, by dimensional regularization of continuum gauge theory. In particular, the Standard Model Callan-Symanzik RG functions are recovered. Moreover, there are no residual lattice artefacts such as a dependence on Wilson-type mass parameters.
Vacuum polarization and chiral lattice fermions
Strathdee, J A
1995-01-01
The vacuum polarization due to chiral fermions on a 4--dimensional Euclidean lattice is calculated according to the overlap prescription. The fermions are coupled to weak and slowly varying background gauge and Higgs fields, and the polarization tensor is given by second order perturbation theory. In this order the overlap constitutes a gauge invariant regularization of the fermion vacuum amplitude. Its low energy -- long wavelength behaviour can be computed explicitly and we verify that it coincides with the Feynman graph result obtainable, for example, by dimensional regularization of continuum gauge theory. In particular, the Standard Model Callan--Symanzik RG functions are recovered. Moreover, there are no residual lattice artefacts such as a dependence on Wilson--type mass parameters.
Two-Component Description for Relativistic Fermions
Institute of Scientific and Technical Information of China (English)
CHEN Yu-Qi; SANG Wen-Long; YANG Lan-Fei
2009-01-01
We propose a two-component form to describe massive relativistic fermions in gauge theories. Relations between the Green's functions in this form and those in the conventional four-component form are derived. It is shown that the S-matrix elements in both forms are exactly the same. The description of the fermion in the new form simplifies significantly the γ-matrix algebra in the four-component form. In particular, in perturbative calculations the propagator of the fermion is a scalar function. As examples, we use this form to reproduce the relativistic spectrum of hydrodron atom, the S-matrix of e+ e-→μ+ μ- and QED one-loop vacuum polarization of photon.
No fermion doubling in quantum geometry
Energy Technology Data Exchange (ETDEWEB)
Gambini, Rodolfo [Instituto de Física, Facultad de Ciencias, Iguá 4225, esq. Mataojo, 11400 Montevideo (Uruguay); Pullin, Jorge, E-mail: pullin@lsu.edu [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803-4001 (United States)
2015-10-07
In loop quantum gravity the discrete nature of quantum geometry acts as a natural regulator for matter theories. Studies of quantum field theory in quantum space–times in spherical symmetry in the canonical approach have shown that the main effect of the quantum geometry is to discretize the equations of matter fields. This raises the possibility that in the case of fermion fields one could confront the usual fermion doubling problem that arises in lattice gauge theories. We suggest, again based on recent results on spherical symmetry, that since the background space–times will generically involve superpositions of states associated with different discretizations the phenomenon may not arise. This opens a possibility of incorporating chiral fermions in the framework of loop quantum gravity.
The Landscape of Free Fermionic Gauge Models
Moore, Douglas G.
A software framework is developed to systematically construct a particular class of weakly coupled free fermionic heterotic string models, dubbed gauge models. In their purest form, these models are maximally supersymmetric (N = 4), and thus only contain superpartners in their matter sector. This feature makes their system- atic construction particularly efficient, and they are thus useful in their simplicity. We first provide a brisk introduction to heterotic strings and the spin-structure construction of free fermionic models. Three systematic surveys are then presented, and we conjecture that these surveys are exhaustive modulo redundancies. Finally we present a collection of metaheuristic algorithms for searching the landscape for models with a user-specified spectrum of phenomenological properties, e.g. gauge group and number of spacetime supersymmetries. Such algorithms provide the groundwork for extended generic free fermionic surveys.
Fermions on one or fewer Kinks
Chu, Yi-Zen
2007-01-01
We find the full spectrum of fermion bound states on a Z_2 kink. In addition to the zero mode, there are int[2 m_f/m_s] bound states, where m_f is the fermion and m_s the scalar mass. We also study fermion modes on the background of a well-separated kink-antikink pair. Using a variational argument, we prove that there is at least one bound state in this background, and that the energy of this bound state goes to zero with increasing kink-antikink separation, 2L, and faster than e^{-a2L} where a = min(m_s, 2 m_f). By numerical evaluation, we find some of the low lying bound states explicitly.
Fermionic NNLO contributions to Bhabha scattering
Actis, S; Gluza, J; Riemann, T
2007-01-01
We derive the two-loop corrections to Bhabha scattering from heavy fermions using dispersion relations. The double-box contributions are expressed by three kernel functions. Convoluting the perturbative kernels with fermionic threshold functions or with hadronic data allows to determine numerical results for small electron mass m_e, combined with arbitrary values of the fermion mass m_f in the loop, $m_e^2<
Scaling of fat-link irrelevant-clover fermions
Zanotti, J M; Leinweber, D B; Williams, A G; 10.1103/PhysRevD.71.034510
2005-01-01
Hadron masses are calculated in quenched lattice QCD on a variety of lattices in order to probe the scaling behavior of the Fat-Link Irrelevant Clover (FLIC) fermion action, a fat-link clover fermion action in which the purely irrelevant operators of the fermion action are constructed using APE-smeared links. The scaling analysis indicates FLIC fermions provide a new form of nonperturbative O(a) improvement where near-continuum results are obtained at finite lattice spacing.
Noether symmetry for non-minimally coupled fermion fields
de Souza, Rudinei C
2008-01-01
A cosmological model where a fermion field is non-minimally coupled with the gravitational field is studied. By applying Noether symmetry the possible functions for the potential density of the fermion field and for the coupling are determined. Cosmological solutions are found showing that the non-minimally coupled fermion field behaves as an inflaton describing an accelerated inflationary scenario, whereas the minimally coupled fermion field describes a decelerated period being identified as dark matter.
Fermionic quantum systems: controllability and the parity superselection rule
Energy Technology Data Exchange (ETDEWEB)
Zeier, Robert; Schulte-Herbrueggen, Thomas [Department Chemie, Technische Universitaet Muenchen, Lichtenbergstrasse 4, 85747 Garching (Germany); Zimboras, Zoltan; Keyl, Michael [Institute for Scientific Interchange Foundation, Villa Gualino, Viale Settimio Severo 75, 10131 Torino (Italy)
2012-07-01
We study controllability and simulability of fermionic quantum systems which observe the parity superselection rule. Superselection rules describe the existence of non-trivial symmetries (e.g., the parity operator) that commute with all physical observables. We present examples of fermionic sytems such as quasifree and translation-invariant ones and develop readily applicable conditions for the controllability of fermionic systems by studying their symmetries. As an application, we discuss under which conditions fermionic and spin systems can simulate each other.
Fermion-fermion scattering in quantum field theory with superconducting circuits.
García-Álvarez, L; Casanova, J; Mezzacapo, A; Egusquiza, I L; Lamata, L; Romero, G; Solano, E
2015-02-20
We propose an analog-digital quantum simulation of fermion-fermion scattering mediated by a continuum of bosonic modes within a circuit quantum electrodynamics scenario. This quantum technology naturally provides strong coupling of superconducting qubits with a continuum of electromagnetic modes in an open transmission line. In this way, we propose qubits to efficiently simulate fermionic modes via digital techniques, while we consider the continuum complexity of an open transmission line to simulate the continuum complexity of bosonic modes in quantum field theories. Therefore, we believe that the complexity-simulating-complexity concept should become a leading paradigm in any effort towards scalable quantum simulations.
Chiral Gravitational Waves from Chiral Fermions
Anber, Mohamed M
2016-01-01
We report on a new mechanism that leads to the generation of primordial chiral gravitational waves, and hence, the violation of the parity symmetry in the Universe. We show that nonperturbative production of fermions with a definite helicity is accompanied by the generation of chiral gravitational waves. This is a generic and model-independent phenomenon that can occur during inflation, reheating and radiation eras, and can leave imprints in the cosmic microwave background polarization and may be observed in future ground- and space-based interferometers. We also discuss a specific model where chiral gravitational waves are generated via the production of light chiral fermions during pseudoscalar inflation.
Novel fat-link fermion actions
Zanotti, J M; Bonnet, F D R; Coddington, P D; Leinweber, D B; Williams, A G; Zhang, J B; Melnitchouk, W; Lee, F X
2002-01-01
The hadron mass spectrum is calculated in lattice QCD using a novel fat-link clover fermion action in which only the irrelevant operators of the fermion action are constructed using smeared links. The simulations are performed on a 16^3 X 32 lattice with a lattice spacing of a=0.125 fm. We compare actions with n=4 and 12 smearing sweeps with a smearing fraction of 0.7. The n=4 Fat Link Irrelevant Clover (FLIC) action provides scaling which is superior to mean-field improvement, and offers advantages over nonperturbative O(a) improvement.
On the integrable gravity coupled to fermions
Belinski, Vladimir A
2016-01-01
In the present paper we indicate an extension of the pure gravity inverse scattering integration technique (developed in [2]) to the case when fermions are present. With this extension the integrability of the maximal supergravity $N=16$ in two space-time dimensions constructed in [1] is revisited. In addition to the results of the article [1] the spectral linear problem proposed in the present paper covers also the Dirac-like fermionic equations of motion and is free of the second order poles with respect to the spectral parameter. The procedure of constructing the exact super-solitonic solutions is outlined.
Cosmic expansion from boson and fermion fields
Energy Technology Data Exchange (ETDEWEB)
De Souza, Rudinei C; Kremer, Gilberto M, E-mail: rudijantsch@gmail.com, E-mail: kremer@fisica.ufpr.br [Departamento de Fisica, Universidade Federal do Parana, Curitiba (Brazil)
2011-06-21
This paper consists in analyzing an action that describes boson and fermion fields minimally coupled to the gravity and a common matter field. The self-interaction potentials of the fields are not chosen a priori but from the Noether symmetry approach. The Noether forms of the potentials allow the boson field to play the role of dark energy and matter and the fermion field to behave as standard matter. The constant of motion and the cyclic variable associated with the Noether symmetry allow the complete integration of the field equations, whose solution produces a universe with alternated periods of accelerated and decelerated expansion.
Cosmic expansion from boson and fermion fields
de Souza, Rudinei C
2011-01-01
This paper consists in analyzing an action that describes boson and fermion fields minimally coupled to the gravity and a common matter field. The self-interaction potentials of the fields are not chosen a priori but from the Noether symmetry approach. The Noether forms of the potentials allow the boson field to play the role of dark energy and matter and the fermion field to behave as standard matter. The constant of motion and the cyclic variable associated with the Noether symmetry allow the complete integration of the field equations, whose solution produces a Universe with alternated periods of accelerated and decelerated expansion.
Bosonization and Cluster Updating of Lattice Fermions
Wiese, U J
1993-01-01
A lattice fermion model is formulated in Fock space using the Jordan-Wigner representation for the fermion creation and annihilation operators. The resulting path integral is a sum over configurations of lattice site occupation numbers $n(x,t) = 0,1$ which may be viewed as bosonic Ising-like variables. However, as a remnant of Fermi statistics a nonlocal sign factor arises for each configuration. When this factor is included in measured observables the bosonic occupation numbers interact locally, and one can use efficient cluster algorithms to update the bosonized variables.
Resonant invisibility with finite range interacting fermions
Energy Technology Data Exchange (ETDEWEB)
Nguenang, Jean-Pierre, E-mail: nguenang@yahoo.com [Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Str. 38, 01187 Dresden (Germany); Fundamental Physics Laboratory: Group of Nonlinear Physics and Complex Systems, Department of Physics, University of Douala, P.O. Box 24157, Douala (Cameroon); Flach, Sergej, E-mail: flach@pks.mpg.de [Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Str. 38, 01187 Dresden (Germany); Khomeriki, Ramaz, E-mail: khomeriki@hotmail.com [Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Str. 38, 01187 Dresden (Germany); Department of Physics, Tbilisi State University, 3 Chavchavadze, 0128 Tbilisi, Georgia (United States)
2012-01-09
We study the eigenstates of two opposite spin fermions on a one-dimensional lattice with finite range interaction. The eigenstates are projected onto the set of Fock eigenstates of the noninteracting case. We find antiresonances for symmetric eigenstates, which eliminate the interaction between two symmetric Fock states when satisfying a corresponding selection rule. -- Highlights: ► We seek the eigenstates of two opposite spin fermions on a one-dimensional lattice with finite range interaction. ► The eigenstates are projected onto the set of Fock eigenstates of the noninteracting case. ► We find antiresonances for symmetric eigenstates when satisfying a corresponding selection rule.
Fermion path integrals and topological phases
Witten, Edward
2016-07-01
Symmetry-protected topological (SPT) phases of matter have been interpreted in terms of anomalies, and it has been expected that a similar picture should hold for SPT phases with fermions. Here a description is given in detail of what this picture means for phases of quantum matter that can be understood via band theory and free fermions. The main examples considered are time-reversal invariant topological insulators and superconductors in two or three space dimensions. Along the way, the precise meaning of the statement that in the bulk of a 3D topological insulator, the electromagnetic θ angle is equal to π , is clarified.
Naturally Light Fermions from Dimensional Reduction
Bietenholz, W; Wiese, U J
2004-01-01
We consider the 3-d Gross-Neveu model in the broken phase and construct a stable brane world by means of a domain wall and an anti-wall. Fermions of opposite chirality are localized on the walls and coupled through the 3-d bulk. At large wall separation \\beta the 2-d correlation length diverges exponentially, hence a 2-d observer cannot distinguish this situation from a 2-d space-time. The 3-d 4-fermion coupling and \\beta fix the effective 2-d coupling such that the asymptotic freedom of the 2-d model arises. This mechanism provides criticality without fine tuning.
Wilson Fermions on a Randomly Triangulated Manifold
Burda, Z; Krzywicki, A
1999-01-01
A general method of constructing the Dirac operator for a randomly triangulated manifold is proposed. The fermion field and the spin connection live, respectively, on the nodes and on the links of the corresponding dual graph. The construction is carried out explicitly in 2-d, on an arbitrary orientable manifold without boundary. It can be easily converted into a computer code. The equivalence, on a sphere, of Majorana fermions and Ising spins in 2-d is rederived. The method can, in principle, be extended to higher dimensions.
A Search for Excited Fermions at HERA
Adloff, C.; Andrieu, B.; Arkadov, V.; Astvatsatourov, A.; Ayyaz, I.; Babaev, A.; Bahr, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Bassler, U.; Bate, P.; Beglarian, A.; Behnke, O.; Beier, C.; Belousov, A.; Benisch, T.; Berger, Christoph; Bernardi, G.; Berndt, T.; Bizot, J.C.; Borras, K.; Boudry, V.; Braunschweig, W.; Brisson, V.; Broker, H.B.; Brown, D.P.; Bruckner, W.; Bruel, P.; Bruncko, D.; Burger, J.; Busser, F.W.; Bunyatyan, A.; Burkhardt, H.; Burrage, A.; Buschhorn, G.; Campbell, A.J.; Cao, Jun; Carli, T.; Caron, S.; Chabert, E.; Clarke, D.; Clerbaux, B.; Collard, C.; Contreras, J.G.; Coughlan, J.A.; Cousinou, M.C.; Cox, B.E.; Cozzika, G.; Cvach, J.; Dainton, J.B.; Dau, W.D.; Daum, K.; Davidsson, M.; Delcourt, B.; Delerue, N.; Demirchyan, R.; De Roeck, A.; De Wolf, E.A.; Diaconu, C.; Dixon, P.; Dodonov, V.; Dowell, J.D.; Droutskoi, A.; Duprel, C.; Eckerlin, Guenter; Eckstein, D.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Ellerbrock, M.; Elsen, E.; Erdmann, M.; Erdmann, W.; Faulkner, P.J.W.; Favart, L.; Fedotov, A.; Felst, R.; Ferencei, J.; Ferron, S.; Fleischer, M.; Flugge, G.; Fomenko, A.; Foresti, I.; Formanek, J.; Foster, J.M.; Franke, G.; Gabathuler, E.; Gabathuler, K.; Garvey, J.; Gassner, J.; Gayler, Joerg; Gerhards, R.; Ghazaryan, Samvel; Goerlich, L.; Gogitidze, N.; Goldberg, M.; Goodwin, C.; Grab, C.; Grassler, H.; Greenshaw, T.; Grindhammer, Guenter; Hadig, T.; Haidt, D.; Hajduk, L.; Haynes, W.J.; Heinemann, B.; Heinzelmann, G.; Henderson, R.C.W.; Hengstmann, S.; Henschel, H.; Heremans, R.; Herrera, G.; Herynek, I.; Hilgers, M.; Hiller, K.H.; Hladky, J.; Hoting, P.; Hoffmann, D.; Hoprich, W.; Horisberger, R.; Hurling, S.; Ibbotson, M.; Issever, C .; Jacquet, M.; Jaffre, M.; Janauschek, L.; Jansen, D.M.; Janssen, X.; Jemanov, V.; Jonsson, L.; Johnson, D.P.; Jones, M.A.S.; Jung, H.; Kastli, H.K.; Kant, D.; Kapichine, M.; Karlsson, M.; Karschnick, O.; Kaufmann, O.; Kausch, M.; Keil, F.; Keller, N.; Kennedy, J.; Kenyon, I.R.; Kermiche, S.; Kiesling, Christian M.; Klein, M.; Kleinwort, C.; Knies, G.; Koblitz, B.; Kolya, S.D.; Korbel, V.; Kostka, P.; Kotelnikov, S.K.; Krasny, M.W.; Krehbiel, H.; Kroseberg, J.; Kruger, K.; Kupper, A.; Kuhr, T.; Kurca, T.; Kutuev, R.; Lachnit, W.; Lahmann, R.; Lamb, D.; Landon, M.P.J.; Lange, W.; Lastovicka, T.; Lebailly, E.; Lebedev, A.; Leissner, B.; Lemrani, R.; Lendermann, V.; Levonian, S.; Lindstroem, M.; Lobodzinska, E.; Lobodzinski, B.; Loktionova, N.; Lubimov, V.; Luders, S.; Luke, D.; Lytkin, L.; Magnussen, N.; Mahlke-Kruger, H.; Malden, N.; Malinovski, E.; Malinovski, I.; Maracek, R.; Marage, P.; Marks, J.; Marshall, R.; Martyn, H.U.; Martyniak, J.; Maxfield, S.J.; Mehta, A.; Meier, K.; Merkel, P.; Metlica, F.; Meyer, H.; Meyer, J.; Meyer, P.O.; Mikocki, S.; Milstead, D.; Mkrtchyan, T.; Mohr, R.; Mohrdieck, S.; Mondragon, M.N.; Moreau, F.; Morozov, A.; Morris, J.V.; Muller, K.; Murin, P.; Nagovizin, V.; Naroska, B.; Naumann, J.; Naumann, Th.; Negri, I.; Nellen, G.; Newman, Paul R.; Nicholls, T.C.; Niebergall, F.; Niebuhr, C.; Nix, O.; Nowak, G.; Nunnemann, T.; Olsson, J.E.; Ozerov, D.; Panassik, V.; Pascaud, C.; Patel, G.D.; Perez, E.; Phillips, J.P.; Pitzl, D.; Poschl, R.; Potachnikova, I.; Povh, B.; Rabbertz, K.; Radel, G.; Rauschenberger, J.; Reimer, P.; Reisert, B.; Reyna, D.; Riess, S.; Rizvi, E.; Robmann, P.; Roosen, R.; Rostovtsev, A.; Royon, C.; Rusakov, S.; Rybicki, K.; Sankey, D.P.C.; Scheins, J.; Schilling, F.P.; Schleper, P.; Schmidt, D.; Schmitt, S.; Schoeffel, L.; Schoning, A.; Schorner, T.; Schroder, V.; Schultz-Coulon, H.C.; Sedlak, K.; Sefkow, F.; Chekelian, V.; Sheviakov, I.; Shtarkov, L.N.; Siegmon, G.; Sievers, P.; Sirois, Y.; Sloan, T.; Smirnov, P.; Solochenko, V.; Solovev, Y.; Spaskov, V.; Specka, Arnd E.; Spitzer, H.; Stamen, R.; Steinhart, J.; Stella, B.; Stellberger, A.; Stiewe, J.; Straumann, U.; Struczinski, W.; Swart, M.; Tasevsky, M.; Tchernyshov, V.; Tchetchelnitski, S.; Thompson, Graham; Thompson, P.D.; Tobien, N.; Traynor, D.; Truoel, Peter; Tsipolitis, G.; Turnau, J.; Turney, J.E.; Tzamariudaki, E.; Udluft, S.; Usik, A.; Valkar, S.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vazdik, Y.; von Dombrowski, S.; Wacker, K.; Wallny, R.; Walter, T.; Waugh, B.; Weber, G.; Weber, M.; Wegener, D.; Wegner, A.; Wengler, T.; Werner, M.; White, G.; Wiesand, S.; Wilksen, T.; Winde, M.; Winter, G.G.; Wissing, C.; Wobisch, M.; Wollatz, H.; Wunsch, E.; Wyatt, A.C.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zhokin, A.; Zomer, F.; Zsembery, J.; zur Nedden, M.
2000-01-01
A search for excited fermions f^* of the first generation in e^+p scattering at the collider HERA is presented using H1 data with an integrated luminosity of 37 pb^(-1). All electroweak decays of excited fermions, f^* -> f gamma, f W, f Z are considered and all possible final states resulting from the Z or W hadronic decays or decays into leptons of the first two generations are taken into account. No evidence for f^* production is found. Mass dependent exclusion limits on cross-sections and on the ratio of coupling constants to the compositeness scale are derived.
Chiral gravitational waves from chiral fermions
Anber, Mohamed M.; Sabancilar, Eray
2017-07-01
We report on a new mechanism that leads to the generation of primordial chiral gravitational waves, and hence, the violation of the parity symmetry in the Universe. We show that nonperturbative production of fermions with a definite helicity is accompanied by the generation of chiral gravitational waves. This is a generic and model-independent phenomenon that can occur during inflation, reheating and radiation eras, and can leave imprints in the cosmic microwave background polarization and may be observed in future ground- and space-based interferometers. We also discuss a specific model where chiral gravitational waves are generated via the production of light chiral fermions during pseudoscalar inflation.
Spinons and parafermions in fermion cosets
Cabra, D C
1997-01-01
We introduce a set of gauge invariant fermion fields in fermionic coset models and show that they play a very central role in the description of several Conformal Field Theories (CFT's). In particular we discuss the explicit realization of primaries and their OPE in unitary minimal models, parafermion fields in $Z_k$ CFT's and that of spinon fields in $SU(N)_k, k=1$ Wess-Zumino-Witten models (WZW) theories. The higher level case ($k>1$) will be briefly discussed. Possible applications to QHE systems and spin-ladder systems are addressed.
Fermionic wigs for BTZ black holes
Energy Technology Data Exchange (ETDEWEB)
Gentile, L.G.C., E-mail: lgentile@pd.infn.it [DISIT, Università del Piemonte Orientale, via T. Michel, 11, Alessandria 15120 (Italy); Dipartimento di Fisica “Galileo Galilei”, Università di Padova, via Marzolo, 8, Padova 35131 (Italy); INFN, Sezione di Padova, via Marzolo, 8, Padova 35131 (Italy); Grassi, P.A., E-mail: pgrassi@mfn.unipmn.it [DISIT, Università del Piemonte Orientale, via T. Michel, 11, Alessandria 15120 (Italy); INFN, Gruppo Collegato di Alessandria, Sezione di Torino (Italy); Mezzalira, A., E-mail: mezzalir@to.infn.it [Dipartimento di Fisica Teorica, Università di Torino, via P. Giuria, 1, Torino 10125 (Italy); INFN, Gruppo Collegato di Alessandria, Sezione di Torino (Italy)
2013-06-11
We compute the wig for the BTZ black hole, namely the complete non-linear solution of supergravity equations with all fermionic zero modes. We use a “gauge completion” method starting from AdS{sub 3} Killing spinors to generate the gravitinos fields associated to the BH and we compute the back-reaction on the metric. Due to the anticommutative properties of the fermionic hairs the resummation of these effects truncates at some order. We illustrate the technique proposed in a precedent paper in a very explicit and analytical form. We also compute the mass, the angular momentum and other charges with their corrections.
The Fermionic Propagator in an Intense Background
Lavelle, Martin
2015-01-01
New results for the fermion propagator in a laser background are presented. We show that the all orders electron propagator can be written in a compact and appealing form as a sum of sideband poles with a matrix wave function renormalisation and a matrix valued mass shift. This last result is essential in the fermionic theory if we are to maintain that both the mass and its square pick up a correction only at order e^2. A perturbative verification of our results is carried out.
Proposal of unified fermion texture
Energy Technology Data Exchange (ETDEWEB)
Krolikowski, W. [Institute of Theoretical Physics, Warsaw University, Warsaw (Poland)
1998-03-01
A unified form of mass matrix is proposed for neutrinos, charged leptons, up quarks and down quarks. Some constraints for the parameters involved are tentatively postulated. Then, the predictions are neatly consistent with available experimental data. Among the predictions are: (i) m{sub {tau}} {approx_equal} 1776.80 MeV (with the inputs of m{sub e} and m{sub {mu}}), (ii) m{sub {nu}0}<
Testing UV-filtered ("fat-link") clover fermions
Capitani, S; Hölbling, C; Capitani, Stefano; Durr, Stephan; Hoelbling, Christian
2006-01-01
We investigate filtered clover fermions, built from fat gauge links, both in one-loop perturbation theory and in numerical simulations. We use a variety of filtering recipes (APE, HYP, EXP, HEX), some of which are suitable for a HMC with dynamical fermions. A generic filtering together with a (fat-link) clover term yields fermions with much reduced chiral symmetry breaking.
Non-perturbative renormalisation of left-left four-fermion operators with Neuberger fermions
Energy Technology Data Exchange (ETDEWEB)
Dimopoulos, P.; Vladikas, A. [INFN, Sezione di Roma ' ' Tor Vegata' ' (Italy)]|[Universita die Roma ' ' Tor Vegata' ' (Italy). Dipt. die Fisica; Giusti, L.; Pena, C. [European Lab. for Particle Physics (CERN), Geneva (Switzerland); Hernandez, P. [Valencia Univ., Burjassot (Spain). Dpto. de Fisica Teorica and IFIC; Palombi, F.; Wittig, H. [Mainz Univ. (Germany). Inst. fuer Kernphysik; Wennekers, J. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2006-07-15
We outline a general strategy for the non-perturbative renormalisation of composite operators in discretisations based on Neuberger fermions, via a matching to results obtained with Wilson-type fermions. As an application, we consider the renormalisation of the four-quark operators entering the {delta}S=1 and {delta}S=2 effective Hamiltonians. Our results are an essential ingredient for the determination of the low-energy constants governing non-leptonic kaon decays. (Orig.)
Non-perturbative renormalisation of left-left four-fermion operators with Neuberger fermions
Dimopoulos, P; Hernández, P; Palombi, Filippo; Peña, C; Vladikas, A; Wennekers, J; Wittig, H
2006-01-01
We outline a general strategy for the non-perturbative renormalisation of composite operators in discretisations based on Neuberger fermions, via a matching to results obtained with Wilson-type fermions. As an application, we consider the renormalisation of the four-quark operators entering the Delta S=1 and Delta S=2 effective Hamiltonians. Our results are an essential ingredient for the determination of the low-energy constants governing non-leptonic kaon decays.
Non-perturbative renormalisation of left-left four-fermion operators with Neuberger fermions
Energy Technology Data Exchange (ETDEWEB)
Dimopoulos, P. [INFN, Sezione di Rome ' Tor Vergata' , c/o Dipartimento di Fisica, Universita di Rome ' Tor Vergata' , Via della Ricerca Scientifica 1, I-00133 Rome (Italy); Giusti, L. [CERN, Physics Department, TH Division, CH-1211 Geneva 23 (Switzerland); Hernandez, P. [Departamento de Fisica Teorica and IFIC, Universitat de Valencia, E-46100 Burjassot (Spain); Palombi, F. [Institut fuer Kernphysik, University of Mainz, D-55099 Mainz (Germany); Pena, C. [CERN, Physics Department, TH Division, CH-1211 Geneva 23 (Switzerland)]. E-mail: carlos.pena.ruano@cern.ch; Vladikas, A. [INFN, Sezione di Rome ' Tor Vergata' , c/o Dipartimento di Fisica, Universita di Rome ' Tor Vergata' , Via della Ricerca Scientifica 1, I-00133 Rome (Italy); Wennekers, J. [DESY, Theory Group, Notkestrasse 85, D-22603 Hamburg (Germany); Wittig, H. [Institut fuer Kernphysik, University of Mainz, D-55099 Mainz (Germany)
2006-09-28
We outline a general strategy for the non-perturbative renormalisation of composite operators in discretisations based on Neuberger fermions, via a matching to results obtained with Wilson-type fermions. As an application, we consider the renormalisation of the four-quark operators entering the {delta}S=1 and {delta}S=2 effective Hamiltonians. Our results are an essential ingredient for the determination of the low-energy constants governing non-leptonic kaon decays.
Non-perturbative renormalisation of left left four-fermion operators with Neuberger fermions
Dimopoulos, P.; Giusti, L.; Hernández, P.; Palombi, F.; Pena, C.; Vladikas, A.; Wennekers, J.; Wittig, H.
2006-09-01
We outline a general strategy for the non-perturbative renormalisation of composite operators in discretisations based on Neuberger fermions, via a matching to results obtained with Wilson-type fermions. As an application, we consider the renormalisation of the four-quark operators entering the ΔS = 1 and ΔS = 2 effective Hamiltonians. Our results are an essential ingredient for the determination of the low-energy constants governing non-leptonic kaon decays.
Fedorov, S A; Kalganova, E S; Sukachev, D D; Golovizin, A A; Tregubov, D O; Khabarova, K Yu; Akimov, A V; Kolachevsky, N N; Sorokin, V N
2016-01-01
We report on the improved measurement of the hyperfine structure of $4f^{12}(^3 H_6)5d_{5/2}6s^2$ $(J=9/2)$ excited state in Tm-169 which is involved in the second-stage laser cooling of Tm. To measure the absolute value of the hyperfine splitting interval we used Doppler-free frequency modulation saturated absorption spectroscopy of Tm atoms in a vapor cell. The sign of the hyperfine constant was determined independently by spectroscopy of laser cooled Tm atoms. The hyperfine constant of the level equals $A_J=-422.112(32)$ MHz that corresponds to the energy difference between two hyperfine sublevels of $-2110.56(16)$~MHz. In relation to the saturated absorption measurement we quantitatively treat contributions of various mechanisms into the line broadening and shift. We consider power broadening in the case when Zeeman sublevels of atomic levels are taken into account. We also discuss the line broadening due to frequency modulation and relative intensities of transitions in saturated-absorption experiments.
Induced Rigid String Action From Fermions
Parthasarathy, R
1999-01-01
From the Dirac action on the world sheet, an effective action is obtained by integrating over the 4-dimensional fermion fields pulled back to the world sheet. This action consists of the Nambu-Goto area term with right dimensionful constant in front, extrinsic curvature action and the topological Euler characteristic term.
Finite volume renormalization scheme for fermionic operators
Energy Technology Data Exchange (ETDEWEB)
Monahan, Christopher; Orginos, Kostas [JLAB
2013-11-01
We propose a new finite volume renormalization scheme. Our scheme is based on the Gradient Flow applied to both fermion and gauge fields and, much like the Schr\\"odinger functional method, allows for a nonperturbative determination of the scale dependence of operators using a step-scaling approach. We give some preliminary results for the pseudo-scalar density in the quenched approximation.
Precision constraints on extra fermion generations.
Erler, Jens; Langacker, Paul
2010-07-16
There has been recent renewed interest in the possibility of additional fermion generations. At the same time there have been significant changes in the relevant electroweak precision constraints, in particular, in the interpretation of several of the low energy experiments. We summarize the various motivations for extra families and analyze them in view of the latest electroweak precision data.
Partial dynamical symmetry in a fermion system
Escher; Leviatan
2000-02-28
The relevance of the partial dynamical symmetry concept for an interacting fermion system is demonstrated. Hamiltonians with partial SU(3) symmetry are presented in the framework of the symplectic shell model of nuclei and shown to be closely related to the quadrupole-quadrupole interaction. Implications are discussed for the deformed light nucleus 20Ne.
Anomalous Hall Effect for chiral fermions
Zhang, P -M
2014-01-01
Semiclassical chiral fermions manifest the anomalous spin-Hall effect: when put into a pure electric field, they suffer a side jump, analogous to what happens to their massive counterparts in non-commutative mechanics. The transverse shift is consistent with the conservation of the angular momentum. In a pure magnetic field a cork-screw-like, spiraling motion is found.
Flavor Constraints on Split Fermion Models
Energy Technology Data Exchange (ETDEWEB)
Lillie, Ben
2003-06-26
We examine the contributions to rare processes that arise in models where the Standard Model fermions are localized at distinct points in compact extra dimensions. Tree-level flavor changing neutral current interactions for the Kaluza-Klein (KK) gauge field excitations are induced in such models, and hence strong constraints are thought to exist on the size of the additional dimensions. We find a general parameterization of the model which does not depend on any specific fermion geography and show that typical values of the parameters can reproduce the fermion hierarchy pattern. Using this parameterization, we reexamine the contributions to neutral meson mixing, rare meson decays, and single top-quark production in e{sup +}e{sup -} collisions. We find that is it possible to evade the stringent bounds for natural regions of the parameters, while retaining finite separations between the fermion fields and without introducing a new hierarchy. The resulting limits on the size of the compact dimension can be as low as TeV{sup -1}.
Strongly interacting two-dimensional Dirac fermions
Lim, L.K.; Lazarides, A.; Hemmerich, Andreas; de Morais Smith, C.
2009-01-01
We show how strongly interacting two-dimensional Dirac fermions can be realized with ultracold atoms in a two-dimensional optical square lattice with an experimentally realistic, inherent gauge field, which breaks time reversal and inversion symmetries. We find remarkable phenomena in a temperature
Axial gravity, massless fermions and trace anomalies
Bonora, L.; Cvitan, M.; Prester, P. Dominis; Pereira, A. Duarte; Giaccari, S.; Štemberga, T.
2017-08-01
This article deals with two main topics. One is odd parity trace anomalies in Weyl fermion theories in a 4d curved background, the second is the introduction of axial gravity. The motivation for reconsidering the former is to clarify the theoretical background underlying the approach and complete the calculation of the anomaly. The reference is in particular to the difference between Weyl and massless Majorana fermions and to the possible contributions from tadpole and seagull terms in the Feynman diagram approach. A first, basic, result of this paper is that a more thorough treatment, taking account of such additional terms and using dimensional regularization, confirms the earlier result. The introduction of an axial symmetric tensor besides the usual gravitational metric is instrumental to a different derivation of the same result using Dirac fermions, which are coupled not only to the usual metric but also to the additional axial tensor. The action of Majorana and Weyl fermions can be obtained in two different limits of such a general configuration. The results obtained in this way confirm the previously obtained ones.
Normalizable fermion modes in a holographic superconductor
Gubser, Steven S; Talavera, Pedro
2009-01-01
We consider fermions in a zero-temperature superconducting anti-de Sitter domain wall solution and find continuous bands of normal modes. These bands can be either partially filled or totally empty and gapped. We present a semi-classical argument which approximately captures the main features of the normal mode spectrum.
Fermionization in an Arbitrary Number of Dimensions
Borstnik, N S Mankoc
2016-01-01
One purpose of this proceedings-contribution is to show that at least for free massless particles it is possible to construct an explicit boson theory which is exactly equivalent in terms of momenta and energy to a fermion theory. The fermions come as $2^{d/2-1}$ families and the to this whole system of fermions corresponding bosons come as a whole series of the Kalb-Ramond fields, one set of components for each number of indexes on the tensor fields. Since Kalb-Ramond fields naturally (only) couple to the extended objects or branes, we suspect that inclusion of interaction into such for a bosonization prepared system - except for the lowest dimensions - without including branes or something like that is not likely to be possible. The need for the families is easily seen just by using the theorem long ago put forward by Aratyn and one of us (H.B.F.N.), which says that to have the statistical mechanics of the fermion system and the boson system to match one needs to have the number of the field components in t...
Emergent Lorentz invariance in fermion sector
Directory of Open Access Journals (Sweden)
Kharuk Ivan
2016-01-01
Full Text Available By using holographic description of strongly interacting field theories we show that under common assumptions Lorentz invariance emerges as an effective low–energy symmetry of the theory, despite fundamental theory at hight energies being Lorentz–violating. We consider fermions sector and show that the notion of chirality also automatically arises in the infrared.
Probabilistic representation of fermionic lattice systems
Energy Technology Data Exchange (ETDEWEB)
Beccaria, Matteo; Presilla, Carlo; De Angelis, Gian Fabrizio; Jona-Lasinio, Giovanni
2000-03-01
We describe an exact Feynman-Kac type formula to represent the dynamics of fermionic lattice systems. In this approach the real time or Euclidean time dynamics is expressed in terms of the stochastic evolution of a collection of Poisson processes. From this formula we derive a family of algorithms for Monte Carlo simulations, parametrized by the jump rates of the Poisson processes.
Flavor Constraints on Split Fermion Models
Lillie, Benjamin Huntington; Lillie, Ben; Hewett, JoAnne
2003-01-01
We examine the contributions to rare processes that arise in models where the Standard Model fermions are localized at distinct points in compact extra dimensions. Tree-level flavor changing neutral current interactions for the Kaluza-Klein (KK) gauge field excitations are induced in such models, and hence strong constraints are thought to exist on the size of the additional dimensions. We find a general parameterization of the model which does not depend on any specific fermion geography and show that typical values of the parameters can reproduce the fermion hierarchy pattern. Using this parameterization, we reexamine the contributions to neutral meson mixing, rare meson decays, and single top-quark production in $e^+e^-$ collisions. We find that is it possible to evade the stringent bounds for natural regions of the parameters, while retaining finite separations between the fermion fields and without introducing a new hierarchy. The resulting limits on the size of the compact dimension can be as low as TeV...
Fermionic realisations of simple Lie algebras
de Azcárraga, J A
2000-01-01
We study the representation ${\\cal D}$ of a simple compact Lie algebra $\\g$ of rank l constructed with the aid of the hermitian Dirac matrices of a (${\\rm dim} \\g$)-dimensional euclidean space. The irreducible representations of $\\g$ contained in ${\\cal D}$ are found by providing a general construction on suitable fermionic Fock spaces. We give full details not only for the simplest odd and even cases, namely su(2) and su(3), but also for the next (${dim} \\g$)-even case of su(5). Our results are far reaching: they apply to any $\\g$-invariant quantum mechanical system containing ${\\rm dim} \\g$ fermions. Another reason for undertaking this study is to examine the role of the $\\g$-invariant fermionic operators that naturally arise. These are given in terms of products of an odd number of gamma matrices, and include, besides a cubic operator, (l-1) fermionic scalars of higher order. The latter are constructed from the Lie algebra cohomology cocycles, and must be considered to be of theoretical significance simila...
Estimation for Entanglement Negativity of Free Fermions
Herzog, Christopher P
2016-01-01
In this letter we study the negativity of one dimensional free fermions. We derive the general form of the $\\mathbb{Z}_{N}$ symmetric term in moments of the partial transposed (reduced) density matrix, which is an algebraic function of the end points of the system. Such a path integral turns out to be a convenient tool for making estimations for the negativity.
Covariant derivative of fermions and all that
Shapiro, Ilya L
2016-01-01
We present detailed pedagogical derivation of covariant derivative of fermions and some related expressions, including commutator of covariant derivatives and energy-momentum tensor of a free Dirac field. The text represents a part of the initial chapter of a one-semester course on semiclassical gravity.
A two-dimensional Dirac fermion microscope
DEFF Research Database (Denmark)
Bøggild, Peter; Caridad, Jose; Stampfer, Christoph
2017-01-01
in the solid state. Here we provide a perspective view on how a two-dimensional (2D) Dirac fermion-based microscope can be realistically implemented and operated, using graphene as a vacuum chamber for ballistic electrons. We use semiclassical simulations to propose concrete architectures and design rules of 2...
Dual of QCD with One Adjoint Fermion
DEFF Research Database (Denmark)
Mojaza, Matin; Nardecchia, Marco; Pica, Claudio;
2011-01-01
We construct the magnetic dual of QCD with one adjoint Weyl fermion. The dual is a consistent solution of the 't Hooft anomaly matching conditions, allows for flavor decoupling and remarkably constitutes the first nonsupersymmetric dual valid for any number of colors. The dual allows to bound the...
Photons with half-integral spin as q-Fermions
Parthasarathy, R
2016-01-01
The recently discovered 'light (photons) with half-integral spin' is interpreted as q-Fermions proposed by us in 1991, as these q-Fermions satisfy q-deformed anti-commutation relations (pertaining to spin half) and have the property that more than one q-Fermion can occupy a given quantum state. In this article, in view of the recent discovery, we recall the construction of q-Fermions and give the statistical properties of q-Fermion gas, based on our preprint in 1992.
Effect of Fermion Velocity on Phase Structure of QED3
Li, Jian-Feng; Feng, Hong-Tao; Zong, Hong-Shi
2016-11-01
Dynamical chiral symmetry breaking (DCSB) in thermal QED3 with fermion velocity is studied in the framework of Dyson-Schwinger equations. By adopting instantaneous approximation and neglecting the transverse component of gauge boson propagator at finite temperature, we numerically solve the fermion self-energy equation in the rainbow approximation. It is found that both DCSB and fermion chiral condensate are suppressed by fermion velocity. Moreover, the critical temperature decreases as fermion velocity increases. Supported in part by the National Natural Science Foundation of China under Grant No. 11535005 and the Natural Science Foundation of Jiangsu Province under Grant No. BK20130387
Resonance spectrum of a bulk fermion on branes
Zhang, Yu-Peng; Du, Yun-Zhi; Guo, Wen-Di; Liu, Yu-Xiao
2016-03-01
It is known that there are two mechanisms for localizing a bulk fermion on a brane: one is the well-known Yukawa coupling, and the other is the new coupling proposed in [Phys. Rev. D 89, 086001 (2014)]. In this paper, we investigate the localization and resonance spectrum of a bulk fermion on the same branes with the two localization mechanisms. It is found that both of the two mechanisms can result in a volcano-like effective potential of the fermion Kaluza-Klein modes. The left-chiral fermion zero mode can be localized on the brane, and there exist some discrete massive-fermion Kaluza-Klein modes that quasilocalized on the branes (also called fermion resonances). The number of the fermion resonances increases linearly with the coupling parameter.
Fermionic-mode entanglement in non-Markovian environment
Cheng, Jiong; Han, Yan; An, Qing-zhi; Zhou, Ling
2015-03-01
We evaluate the non-Markovian effects on the entanglement dynamics of a fermionic system interacting with two dissipative vacuum reservoirs. The exact solution of density matrix is derived by utilizing the Feynman-Vernon influence functional theory in the fermionic coherent state representation and the Grassmann calculus, which are valid for both the fermionic and bosonic baths, and their difference lies in the dependence of the parity of the initial states. The fermionic entanglement dynamics is presented by adding an additional restriction to the density matrix known as the superselection rules. Our analysis shows that the usual decoherence suppression schemes implemented in qubits systems can also be achieved for systems of identical fermions, and the initial state proves its importance in the evolution of fermionic entanglement. Our results provide a potential way to decoherence controlling of identical fermions.
Resonance spectrum of a bulk fermion on branes
Zhang, Yu-Peng; Guo, Wen-Di; Liu, Yu-Xiao
2016-01-01
It is known that there are two mechanisms for localizing a bulk fermion on a brane, one is the well-known Yukawa coupling and the other is the new coupling proposed in [Phys. Rev. D 89, 086001 (2014)]. In this paper, we investigate localization and resonance spectrum of a bulk fermion on the same branes with the two localization mechanisms. It is found that both the two mechanisms can result in a volcano-like effective potential of the fermion Kaluza-Klein modes. The left-chiral fermion zero mode can be localized on the brane and there exist some discrete massive fermion Kaluza-Klein modes that quasilocalized on the brane (also called fermion resonances). The number of the fermion resonances increases linearly with the coupling parameter.
Isotope shifts of 6s5d $^3$D-states in neutral Barium
Dammalapati, U; Jungmann, K; Willmann, L
2008-01-01
Laser spectroscopy of the low lying $^1$P and $^3$D states in atomic barium has been performed. This work contributes substantially to the development of an effective laser cooling and trapping for heavy alkaline earth elements and aims in particular for a better understanding of the atomic wave function of these systems. Isotope shifts and hyperfine structures are ideal probes for the wave functions at the position of the nucleus. This is essential input for a theoretical evaluation of the sensitivity to fundamental symmetry breaking properties like permanent electric dipole moments. We report the first isotope shift measurements of the $^3$D$_{1,2}$-$^1$P$_1$ transitions. A deviation of the King plot from its expected behavior has been observed. Further we have optically resolved the hyperfine structure of the $^3$D$_{1,2}$ states.
The fermion bag approach to lattice field theories
Chandrasekharan, Shailesh
2009-01-01
We propose a new approach to the fermion sign problem in systems where there is a coupling $U$ such that when it is infinite the fermions are paired into bosons and there is no fermion permutation sign to worry about. We argue that as $U$ becomes finite fermions are liberated but are naturally confined to regions which we refer to as {\\em fermion bags}. The fermion sign problem is then confined to these bags and may be solved using the determinantal trick. In the parameter regime where the fermion bags are small and their typical size does not grow with the system size, construction of Monte Carlo methods that are far more efficient than conventional algorithms should be possible. In the region where the fermion bags grow with system size, the fermion bag approach continues to provide an alternative approach to the problem but may lose its main advantage in terms of efficiency. The fermion bag approach also provides new insights and solutions to sign problems. A natural solution to the "silver blaze problem" ...
Peltier cooling of fermionic quantum gases.
Grenier, Ch; Georges, A; Kollath, C
2014-11-14
We propose a cooling scheme for fermionic quantum gases, based on the principles of the Peltier thermoelectric effect and energy filtering. The system to be cooled is connected to another harmonically trapped gas acting as a reservoir. The cooling is achieved by two simultaneous processes: (i) the system is evaporatively cooled, and (ii) cold fermions from deep below the Fermi surface of the reservoir are injected below the Fermi level of the system, in order to fill the "holes" in the energy distribution. This is achieved by a suitable energy dependence of the transmission coefficient connecting the system to the reservoir. The two processes can be viewed as simultaneous evaporative cooling of particles and holes. We show that both a significantly lower entropy per particle and faster cooling rate can be achieved in this way than by using only evaporative cooling.
Peltier Cooling of Fermionic Quantum Gases
Grenier, Ch.; Georges, A.; Kollath, C.
2014-11-01
We propose a cooling scheme for fermionic quantum gases, based on the principles of the Peltier thermoelectric effect and energy filtering. The system to be cooled is connected to another harmonically trapped gas acting as a reservoir. The cooling is achieved by two simultaneous processes: (i) the system is evaporatively cooled, and (ii) cold fermions from deep below the Fermi surface of the reservoir are injected below the Fermi level of the system, in order to fill the "holes" in the energy distribution. This is achieved by a suitable energy dependence of the transmission coefficient connecting the system to the reservoir. The two processes can be viewed as simultaneous evaporative cooling of particles and holes. We show that both a significantly lower entropy per particle and faster cooling rate can be achieved in this way than by using only evaporative cooling.
Playing with fermion couplings in Higgsless models
Casalbuoni, R; Dolce, D; Dominici, Daniele
2005-01-01
We discuss the fermion couplings in a four dimensional SU(2) linear moose model by allowing for direct couplings between the left-handed fermions on the boundary and the gauge fields in the internal sites. This is realized by means of a product of non linear $\\sigma$-model scalar fields which, in the continuum limit, is equivalent to a Wilson line. The effect of these new non local couplings is a contribution to the $\\epsilon_3$ parameter which can be of opposite sign with respect to the one coming from the gauge fields along the string. Therefore, with some fine tuning, it is possible to satisfy the constraints from the electroweak data.
Exact fermionic Green's functions from holograpny
Fan, ZhongYing
2014-01-01
We construct a series of charged dilatonic black holes which share zero entropy in the zero temperature limit using Einstein-Maxwell-Dilaton theories. In these black holes, the wave functions and the Green's functions of massless fermions can be solved exactly in terms of special functions in the phase space of $(\\omega,k)$. We observe that for sufficiently large charge, there are many poles in the Green's function with vanishing $\\omega$, which strongly signifies that Fermi surfaces exist in these holographic systems. The new distinguishing properties of the Green's function arising in these systems were illustrated with great details. We also study the poles motion of the Green's function for arbitrary (complex) frequency. Our analytic results provide a more realistic and elegant approach to study strongly correlated fermionic systems using gauge/gravity duality.
Chiral scars in chaotic Dirac fermion systems.
Xu, Hongya; Huang, Liang; Lai, Ying-Cheng; Grebogi, Celso
2013-02-08
Do relativistic quantum scars in classically chaotic systems possess unique features that are not shared by nonrelativistic quantum scars? We report a class of relativistic quantum scars in massless Dirac fermion systems whose phases return to the original values or acquire a 2π change only after circulating twice about some classical unstable periodic orbits. We name such scars chiral scars, the successful identification of which has been facilitated tremendously by our development of an analytic, conformal-mapping-based method to calculate an unprecedentedly large number of eigenstates with high accuracy. Our semiclassical theory indicates that the physical origin of chiral scars can be attributed to a combined effect of chirality intrinsic to massless Dirac fermions and the geometry of the underlying classical orbit.
Detection prospects of singlet fermionic dark matter
Esch, Sonja; Yaguna, Carlos E
2013-01-01
A singlet fermion which interacts only with a new singlet scalar provides a viable and minimal scenario that can explain the dark matter. The singlet fermion is the dark matter particle whereas the new scalar mixes with the Higgs boson providing a link between the dark matter sector and the Standard Model. In this paper, we present an updated analysis of this model focused on its detection prospects. Both, the parity-conserving case and the most general case are considered. First, the full parameter space of the model is analyzed, and the regions compatible with the dark matter constraint are obtained and characterized. Then, the implications of current and future direct detection experiments are taken into account. Specifically, we determine the regions of the multidimensional parameter space that are currently excluded and those that are going to be probed by next generation experiments. Finally, indirect detection prospects are discussed and the expected signal at neutrino telescopes is calculated.
Detection prospects of singlet fermionic dark matter
Esch, Sonja; Klasen, Michael; Yaguna, Carlos E.
2013-10-01
A singlet fermion which interacts only with a new singlet scalar provides a viable and minimal scenario that can explain the dark matter. The singlet fermion is the dark matter particle whereas the new scalar mixes with the Higgs boson providing a link between the dark matter sector and the standard model. In this paper, we present an updated analysis of this model focused on its detection prospects. Both the parity-conserving case and the most general case are considered. First, the full parameter space of the model is analyzed, and the regions compatible with the dark matter constraint are obtained and characterized. Then, the implications of current and future direct detection experiments are taken into account. Specifically, we determine the regions of the multidimensional parameter space that are currently excluded and those that are going to be probed by next generation experiments. Finally, indirect detection prospects are discussed and the expected signal at neutrino telescopes is calculated.
Extending exchange symmetry beyond bosons and fermions
Tichy, Malte C.; Mølmer, Klaus
2017-08-01
We study quantum many-body states of particles subject to a more general exchange symmetry than the behavior under pairwise exchange obeyed by bosons and fermions. We refer to these hypothetical particles as immanons because the scalar product of states with the generalized exchange symmetry is the immanant of the matrix containing all mutual scalar products of the occupied single-particle states, a generalization of the determinant and permanent applied for fermions and bosons. Immanons are shown to obey a partial Pauli principle that forbids the occupation of single-particle states above certain threshold numbers. This has measurable consequences for their tendency to favor or oppose multiple occupation of single-particle modes, and it links conjectured mathematical properties of immanants to the expected outcome of a physical Gedanken experiment.
Fermion dark matter from SO(10)
Arbelaez, Carolina; Restrepo, Diego; Zapata, Oscar
2016-01-01
We construct and analyze non-supersymmetric SO(10) standard model extensions which explain dark matter (DM) through the fermionic Higgs portal. In these SO(10)-based models the DM particle is naturally stable since a $Z_2$ discrete symmetry, the matter parity, is left at the end of the symmetry breaking chain to the standard model. Potentially realistic models contain the $\\bf{10}$ and $\\bf{45}$ fermionic representations from which a neutralino-like mass matrix with arbitrary mixings can be obtained. Two different SO(10) breaking chains will be analyzed in light of gauge coupling unification: the standard path $\\text{SU}(5)\\times U(1)_{X}$ and the left-right symmetry intermediate chain. The former opens the possibility of a split supersymmetric-like spectrum with an additional (inert) scalar doublet, while the later requires additional exotic scalar representations associated to the breaking of the left-right symmetry.
Thermometry for Dirac fermions in graphene
Energy Technology Data Exchange (ETDEWEB)
Liu, Fan-Hung; Hsu, Chang-Shun; Lo, Shun-Tsung [National Taiwan University, Taipei, Taiwan (China); and others
2015-01-15
We use both the zero-magnetic-field resistivity and the phase coherence time determined by weak localization as independent thermometers for Dirac fermions (DF) in multilayer graphene. In the high current (I) region, there exists a simple power law T{sub DF} ∼ I{sup ∼0.5}, where T{sub DF} is the effective Dirac fermion temperature for epitaxial graphene on SiC. In contrast, T{sub DF} ∼ I{sup ∼1} in exfoliated multilayer graphene. We discuss possible reasons for the different power laws observed in these multilayer graphene systems. Our experimental results on DF-phonon scattering may find applications in graphene-based nanoelectronics.
Equilibration via Gaussification in Fermionic Lattice Systems
Gluza, M.; Krumnow, C.; Friesdorf, M.; Gogolin, C.; Eisert, J.
2016-11-01
In this Letter, we present a result on the nonequilibrium dynamics causing equilibration and Gaussification of quadratic noninteracting fermionic Hamiltonians. Specifically, based on two basic assumptions—clustering of correlations in the initial state and the Hamiltonian exhibiting delocalizing transport—we prove that non-Gaussian initial states become locally indistinguishable from fermionic Gaussian states after a short and well controlled time. This relaxation dynamics is governed by a power-law independent of the system size. Our argument is general enough to allow for pure and mixed initial states, including thermal and ground states of interacting Hamiltonians on large classes of lattices as well as certain spin systems. The argument gives rise to rigorously proven instances of a convergence to a generalized Gibbs ensemble. Our results allow us to develop an intuition of equilibration that is expected to be more generally valid and relates to current experiments of cold atoms in optical lattices.
O(a^2) corrections to the fermion propagator and fermion bilinears
Constantinou, M; Stylianou, F
2008-01-01
We present the corrections to the fermion propagator, to second order in the lattice spacing, O(a^2), in 1-loop perturbation theory. The fermions are described by the clover action and for the gluons we use a 3-parameter family of Symanzik improved actions. Our calculation has been carried out in a general covariant gauge. The results are provided as a polynomial of the clover parameter, and are tabulated for 10 popular sets of the Symanzik coefficients (Plaquette, Tree-level Symanzik, Iwasaki, TILW and DBW2 action). We also study the O(a^2) corrections to matrix elements of fermion bilinear operators that have the form $\\bar\\Psi\\Gamma\\Psi$, where $\\Gamma$ denotes all possible distinct products of Dirac matrices. These correction terms are essential ingredients for improving, to O(a^2), the matrix elements of the fermion operators. Our results are applicable also to the case of twisted mass fermions. A longer write-up of this work, including non-perturbative results, is in preparation together with V. Gimenez...
DDalphaAMG for Twisted Mass Fermions
Bacchio, Simone; Finkenrath, Jacob; Frommer, Andreas; Kahl, Karsten; Rottmann, Matthias
2016-01-01
We present the Adaptive Aggregation-based Domain Decomposition Multigrid method extended to the twisted mass fermion discretization action. We show comparisons of results as a function of tuning the parameters that enter the twisted mass version of the DDalphaAMG library (https://github.com/sbacchio/DDalphaAMG). Moreover, we linked the DDalphaAMG library to the tmLQCD software package and give details on the performance of the multigrid solver during HMC simulations at the physical point.
Self-consistent model of fermions
Yershov, V N
2002-01-01
We discuss a composite model of fermions based on three-flavoured preons. We show that the opposite character of the Coulomb and strong interactions between these preons lead to formation of complex structures reproducing three generations of quarks and leptons with all their quantum numbers and masses. The model is self-consistent (it doesn't use input parameters). Nevertheless, the masses of the generated structures match the experimental values.
Two dimensional fermions in four dimensional YM
Narayanan, R
2009-01-01
Dirac fermions in the fundamental representation of SU(N) live on a two dimensional torus flatly embedded in $R^4$. They interact with a four dimensional SU(N) Yang Mills vector potential preserving a global chiral symmetry at finite $N$. As the size of the torus in units of $\\frac{1}{\\Lambda_{SU(N)}}$ is varied from small to large, the chiral symmetry gets spontaneously broken in the infinite $N$ limit.
Numerical properties of staggered overlap fermions
de Forcrand, Philippe; Panero, Marco
2010-01-01
We report the results of a numerical study of staggered overlap fermions, following the construction of Adams which reduces the number of tastes from 4 to 2 without fine-tuning. We study the sensitivity of the operator to the topology of the gauge field, its locality and its robustness to fluctuations of the gauge field. We make a first estimate of the computing cost of a quark propagator calculation, and compare with Neuberger's overlap.
Overlap fermions on a twisted mass sea
Bär, O; Schäefer, S; Scorzato, L; Shindler, A
2006-01-01
We present first results of a mixed action project. We analyze gauge configurations generated with two flavors of dynamical twisted mass fermions. Neuberger's overlap Dirac operator is used for the valence sector. The various choices in the setup of the simulation are discussed. We employ chiral perturbation theory to describe the effects of using different actions in the sea and valence sector at non-zero lattice spacing.
Precision Constraints on Extra Fermion Generations
Erler, Jens
2010-01-01
In the recent past there has been renewed interest in the possibility of additional fermion generations. At the same time there have been significant changes in the relevant electroweak (EW) precision constraints, in particular in the interpretation of several of the low energy experiments. We summarize the various motivations for the increased activity regarding extra families and analyze them in view of the latest EW precision data.
Renormalization group for non-relativistic fermions.
Shankar, R
2011-07-13
A brief introduction is given to the renormalization group for non-relativistic fermions at finite density. It is shown that Landau's theory of the Fermi liquid arises as a fixed point (with the Landau parameters as marginal couplings) and its instabilities as relevant perturbations. Applications to related areas, nuclear matter, quark matter and quantum dots, are briefly discussed. The focus will be on explaining the main ideas to people in related fields, rather than addressing the experts.
Fermionic Optical Lattices: A Computational Study
2014-10-22
Kevin Schmidt, Shiwei Zhang. Auxiliary-field quantum Monte Carlo method for strongly paired fermions, Physical Review A, (12 2011): 0. doi...10.1103/PhysRevA.84.061602 A. Euverte, F. Hébert, S. Chiesa, R. Scalettar, G. Batrouni. Kondo Screening and Magnetism at Interfaces, Physical Review Letters...contact interaction: Magnetic properties in a dilute Hubbard model, Physical Review A, (12 2010): 0. doi: 10.1103/PhysRevA.82.061603 S. Zhou, D
Superpersistent Currents in Dirac Fermion Systems
2017-03-06
TITLE AND SUBTITLE Superpersistent Currents in Dirac Fermion Systems 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9550-15-1-0151 5c. PROGRAM ELEMENT...currents in 2D Dirac material systems and pertinent phenomena in the emerging field of relativistic quantum nonlinear dynamics and chaos. Systematic...anomalous optical transitions, and spin control in topological insulator quantum dots, (4) the discovery of nonlinear dynamics induced anomalous Hall
Majorana fermions coupled to electromagnetic radiation
Ohm, Christoph; Hassler, Fabian
2013-01-01
We consider a voltage-biased Josephson junction between two nanowires hosting Majorana zero modes which occur as topological protected zero-energy excitations at the junction. We show that two Majorana fermions localized at the junction, even though being neutral particles, interact with the electromagnetic field and generate coherent radiation similar to the conventional Josephson radiation. Within a semiclassical analysis of the radiation field, we find that the optical phase gets locked to...
Optical Lattice Simulations of Correlated Fermions
2013-10-04
simple-cubic optical lattice, , (06 2009): 0. doi: 09/20/2013 51.00 Tin-Lun Ho, Qi Zhou. Squeezing out the entropy of fermions in optical lattices...Convention and Exhibition Center, Hong Kong, May 12, 2009 "Reducing Entropy in Quantum Gases in optical lattices", Jason Ho, Aspen workshop on quantum...Sciences Randall Hulet: chosen as a 2010 Outstanding Referee of the Physical Review and Physical Review Letters Journals Randall Hulet: Willis E. Lamb
Heavy fermion material: Ce versus Yb case
Flouquet, J.; Harima, H.
2009-01-01
Heavy fermion compounds are complex systems but excellent materials to study quantum criticality with the switch of different ground states. Here a special attention is given on the interplay between magnetic and valence instabilities which can be crossed or approached by tuning the system by pressure or magnetic field. By contrast to conventional rare earth magnetism or classical s wave superconductivity, strong couplings may occur with drastic changes in spin or charge dynamics. Measurement...
Hypercubic smeared links for dynamical fermions
Energy Technology Data Exchange (ETDEWEB)
Hasenfratz, A.; Hoffmann, R. [Colorado Univ., Boulder, CO (United States). Dept. of Physics; Schaefer, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC
2007-02-15
We investigate a variant of hypercubic gauge link smearing where the SU(3) projection is replaced with a normalization to the corresponding unitary group. This smearing is differentiable and thus suitable for use in dynamical fermion simulations using molecular dynamics type algorithms. We show that this smearing is as efficient as projected hypercubic smearing in removing ultraviolet noise from the gauge fields. We test the normalized hypercubic smearing in dynamical improved (clover) Wilson and valence overlap simulations. (orig.)
Nucleon electromagnetic form factors with Wilson fermions
Energy Technology Data Exchange (ETDEWEB)
Goeckeler, M. [Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Haegler, P. [Technische Univ. Muenchen, Garching (Germany). Inst. fuer Theoretische Physik; Horsley, R. [Edinburgh Univ. (GB). School of Physics] (and others)
2007-10-15
The nucleon electromagnetic form factors continue to be of major interest for experimentalists and phenomenologists alike. They provide important insights into the structure of nuclear matter. For a range of interesting momenta they can be calculated on the lattice. The limiting factor continues to be the value of the pion mass. We present the latest results of the QCDSF collaboration using gauge configurations with two dynamical, non-perturbatively improved Wilson fermions at pion masses as low as 350 MeV. (orig.)
Optical Lattice Gases of Interacting Fermions
2015-12-02
theoretical research supported by this grant focused on discovering new phases of quantum matter for ultracold fermionic atoms or molecules confined in optical... theoretically a “topological ladder”, i.e. a ladder-like optical lattice containing ultracold atoms in higher orbital bands [15] in the absence of...seemed hard or impossible to achieve in traditional solids. Publications stemming from the research effort: 1. Xiaopeng Li, W. Vincent Liu
Chiral random matrix theory for staggered fermions
Osborn, James C
2012-01-01
We present a completed random matrix theory for staggered fermions which incorporates all taste symmetry breaking terms at their leading order from the staggered chiral Lagrangian. This is an extension of previous work which only included some of the taste breaking terms. We will also discuss the effects of taste symmetry breaking on the eigenvalues in the weak and strong taste breaking limits, and compare with some results from lattice simulations.
The Principle of the Fermionic Projector, Appendices
2002-01-01
The "principle of the fermionic projector" provides a new mathematical framework for the formulation of physical theories and is a promising approach for physics beyond the standard model. The book begins with a brief review of relativity, relativistic quantum mechanics and classical gauge theories, with the emphasis on the basic physical concepts and the mathematical foundations. The external field problem and Klein's paradox are discussed and then resolved by introducing the so-called fermi...
Kinetic theory of fermions in curved spacetime
Fidler, Christian; Pitrou, Cyril
2017-06-01
We build a statistical description of fermions, taking into account the spin degree of freedom in addition to the momentum of particles, and we detail its use in the context of the kinetic theory of gases of fermions particles. We show that the one-particle distribution function needed to write a Liouville equation is a spinor valued operator. The degrees of freedom of this function are covariantly described by an intensity function and by a polarisation vector which are parallel transported by free streaming. Collisions are described on the microscopic level and lead to a Boltzmann equation for this operator. We apply our formalism to the case of weak interactions, which at low energies can be considered as a contact interaction between fermions, allowing us to discuss the structure of the collision term for a few typical weak-interaction mediated reactions. In particular we find for massive particles that a dipolar distribution of velocities in the interacting species is necessary to generate linear polarisation, as opposed to the case of photons for which linear polarisation is generated from the quadrupolar distribution of velocities.
Composite gauge-bosons made of fermions
Suzuki, Mahiko
2016-07-01
We construct a class of Abelian and non-Abelian local gauge theories that consist only of matter fields of fermions. The Lagrangian is local and does not contain an auxiliary vector field nor a subsidiary condition on the matter fields. It does not involve an extra dimension nor supersymmetry. This Lagrangian can be extended to non-Abelian gauge symmetry only in the case of SU(2) doublet matter fields. We carry out an explicit diagrammatic computation in the leading 1 /N order to show that massless spin-one bound states appear with the correct gauge coupling. Our diagram calculation exposes the dynamical features that cannot be seen in the formal auxiliary vector-field method. For instance, it shows that the s -wave fermion-antifermion interaction in the 3S1 channel (ψ ¯ γμψ ) alone cannot form the bound gauge bosons; the fermion-antifermion pairs must couple to the d -wave state too. One feature common to our class of Lagrangian is that the Noether current does not exist. Therefore it evades possible conflict with the no-go theorem of Weinberg and Witten on the formation of the non-Abelian gauge bosons.
Composite gauge-bosons made of fermions
Suzuki, Mahiko
2016-01-01
We construct a class of Abelian and non-Abelian local gauge theories that consist only of matter fields of fermions. The Lagrangian is compact and local without containing an auxiliary vector field nor a subsidiary condition on the matter fields. Because of the special structure, this Lagrangian can be extended to non-Abelian gauge symmetry only in the case of SU(2) doublet matter fields. We carry out explicit dynamical computation in the leading 1/N order to show that massless spin-one bound states appear with the correct gauge coupling. Our diagram calculation exposes the dynamical features that cannot be explored in the formal auxiliary vector-field trick. For instance, it shows that the s-wave fermion-antifermion interaction alone cannot form the bound gauge-bosons; the fermion-antifermion pairs must couple to the d-wave state too. Since our models are unrenormalizable in the world of (3+1) dimension, they can be phenomenologically relevant, if at all, only when momentum cutoff is introduced.
Mixtures of Ultracold Fermions with Unequal Masses
de Melo, Carlos A. R. Sa
2008-05-01
The quantum phases of ultracold fermions with unequal masses are discussed in continuum and lattice models for a wide variety of mixtures which exhibit Feshbach resonances, e.g., mixtures of ^6Li and ^40K. The evolution of superfluidity from the Bardeen-Cooper-Schrieffer (BCS) to the Bose-Einstein condensation (BEC) regime in the continuum is analyzed as a function of scattering parameter, population imbalance and mass anisotropy. In the continuum case, regions corresponding to normal, phase-separated or coexisting uniform-superfluid/excess-fermion phases are identified and the possibility of topological phase transitions is discussed [1]. For optical lattices, the phase diagrams as a function of interaction strength, population imbalance, filling fraction and tunneling parameters are presented [2]. In addition to the characteristic phases of the continuum, a series of insulating phases emerge in the phase diagrams of optical lattices, including a Bose-Mott insulator (BMI), a Fermi-Pauli insulator (FPI), a phase-separated BMI/FPI mixture, and a Bose-Fermi checkerboard (BFC) phase. Lastly, the effects of harmonic traps and the emergence of unusual shell structures are discussed for mixtures of fermions with unequal masses. [1] M. Iskin, and C. A. R. S' a de Melo, Phys. Rev. Lett 97, 100404 (2006); [2] M. Iskin, and C. A. R. S' a de Melo, Phys. Rev. Lett. 99, 080403 (2007).
Higher loop renormalization of fermion bilinear operators
Skouroupathis, A
2007-01-01
We compute the two-loop renormalization functions, in the RI' scheme, of local bilinear quark operators $\\bar\\psi\\Gamma\\psi$, where $\\Gamma$ denotes the Scalar and Pseudoscalar Dirac matrices, in the lattice formulation of QCD. We consider both the flavor non-singlet and singlet operators; the latter, in the scalar case, leads directly to the two-loop fermion mass renormalization, $Z_m$. As a prerequisite for the above, we also compute the quark field renormalization, $Z_\\psi$, up to two loops. We use the clover action for fermions and the Wilson action for gluons. Our results are given as a polynomial in $c_{SW}$, in terms of both the renormalized and bare coupling constant, in the renormalized Feynman gauge. We also confirm the 1-loop renormalization functions, for generic gauge. A longer write-up of the present work, including the conversion of our results to the MSbar scheme and a generalization to arbitrary fermion representations, can be found in arXiv:0707.2906 .
Phase diagram and non-Abelian symmetry locking for fermionic mixtures with unequal interactions
Pinto Barros, Joao C.; Lepori, Luca; Trombettoni, Andrea
2017-07-01
The realization of experiments in ultracold multicomponent mixtures, also involving more atomic species, opened the way to the study of exotic quantum phases and unconventional superfluidity, as, for instance non-Abelian superfluid phases. In this paper we study the occurrence of non-Abelian symmetry-locked superfluid states in ultracold fermionic mixtures with four components, showing that such states can be studied in current day experiments with 171Yb-173Yb isotopes. We study the phase diagram in the presence of an attractive interaction between the species of two pairs of the mixture, and general (also repulsive) interactions between the species of each pair. This system can be physically realized, e.g., in mixtures of two different earth-alkaline species, both of them with two hyperfine levels selectively populated. We find an extended region of the diagram exhibiting a two-flavors superfluid symmetry-locking (TFSL) phase. The locking corresponds to the presence of a order parameter involving—in all the possible and distinct permitted ways—two fermions, one of them belonging to the first pair and the second to the other one. This TSFL phase is present also for not too large repulsive intrapair interactions and it is characterized by a global non-Abelian symmetry group obtained by locking together two independent invariance groups of the corresponding normal state. Explicit estimates are reported for the mixture of the fermionic isotopes 171Yb-173Yb , indicating that the TFSL phase can be achieved also without tuning the interactions between Yb atoms.
Neutral atom traps of rare isotopes
Mueller, Peter
2016-09-01
Laser cooling and trapping techniques offer exquisite control of an atom's external and internal degrees of freedom. The species of interest can be selectively captured, cooled close to absolute zero temperatures, and observed with high signal-to-noise ratio. Moreover, the atom's electronic and magnetic state populations can be precisely manipulated and interrogated. Applied in nuclear physics, these techniques are ideal for precision measurements in the fields of fundamental interactions and symmetries, nuclear structure studies, and isotopic trace analysis. In particular, they offer unique opportunities in the quest for physics beyond the standard model. I will shortly review the basics of this approach and the state of the field and then cover in more details recent results from two such efforts: the search for a permanent electric dipole moment in 225Ra and the beta-neutrino angular correlation measurement with laser trapped 6He. This work is supported by the U.S. DOE, Office of Science, Office of Nuclear Physics, under Contract DE-AC02-06CH11357.
Fermions in higher representations. Some results about SU(2) with adjoint fermions
Del Debbio, L; Pica, C
2008-01-01
We discuss the lattice formulation of gauge theories with fermions in arbitrary representations of the color group, and present the implementation of the RHMC algorithm for simulating dynamical Wilson fermions. A first dataset is presented for the SU(2) gauge theory with two fermions in the adjoint representation, which has been proposed as a possible technicolor candidate. Simulations are performed on 8^3x16 lattices, at fixed lattice spacing. The PCAC mass, the pseudoscalar, vector and axial meson masses, the pseudoscalar meson decay constant are computed. The extrapolation to the chiral limit is discussed. However more extensive investigations are needed in order to control the systematic errors in the numerical results, and then understand in detail the phase structure of these theories.
Continuum-limit scaling of overlap fermions as valence quarks
Energy Technology Data Exchange (ETDEWEB)
Cichy, Krzysztof [Adam Mickiewicz Univ., Poznan (Poland). Faculty of Physics; Herdoiza, Gregorio; Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC
2009-10-15
We present the results of a mixed action approach, employing dynamical twisted mass fermions in the sea sector and overlap valence fermions, with the aim of testing the continuum limit scaling behaviour of physical quantities, taking the pion decay constant as an example. To render the computations practical, we impose for this purpose a fixed finite volume with lattice size L{approx}1.3 fm. We also briefly review the techniques we have used to deal with overlap fermions. (orig.)
On fermion masses in a dimensional reduction scheme
Energy Technology Data Exchange (ETDEWEB)
Barnes, K.J.; Forgacs, P.; Surridge, M.; Zoupanos, G.
1987-01-01
A candidate model for Grand Unification, arising from a Coset Space Dimensional Reduction scheme based on an E(7) gauge theory, is found to have a promising set of fermionic quantum numbers. Unfortunately, these fermions all develop large (geometric) masses. We derive formulae for the square of the Dirac operator and for fermion masses for a large class of CSDR schemes, revealing this as a general feature.
Localization of massive and massless fermion on two field brane
Farokhtabar, A
2016-01-01
In this paper we study fermion localization and resonances on a special type of braneworld model supporting brane splitting. In such models one can construct multi-wall branes which cause considerable simplification in field equations. We use a polynomial superpotential to construct this brane. The suitable Yukawa coupling between the background scalar field and localized fermion is determined. The massive fermion resonance spectrum is obtained. The number of resonances is increased for higher values of Yukawa coupling.
Semiclassical fermion pair creation in de Sitter spacetime
Energy Technology Data Exchange (ETDEWEB)
Stahl, Clément, E-mail: clement.stahl@icranet.org; Eckhard, Strobel, E-mail: eckhard.strobel@irap-phd.eu [ICRANet, Piazzale della Repubblica 10, 65122 Pescara (Italy); Dipartimento di Fisica, Università di Roma “La Sapienza”, Piazzale Aldo Moro 5, 00185 Rome (Italy); Université de Nice Sophia Antipolis, 28 Avenue de Valrose, 06103 Nice Cedex 2 (France)
2015-12-17
We present a method to semiclassically compute the pair creation rate of bosons and fermions in de Sitter spacetime. The results in the bosonic case agree with the ones in the literature. We find that for the constant electric field the fermionic and bosonic pair creation rate are the same. This analogy of bosons and fermions in the semiclassical limit is known from several flat spacetime examples.
Fermion Bound States Around Skyrmions in Doped Antiferromagnets
Institute of Scientific and Technical Information of China (English)
寇谡鹏
2003-01-01
We show the skyrmion effects in doped antiferromagnets for the uniform flux phase. The low-energy effective theory of the t′-J model can be mapped onto the massive quantum electrodynamics. There exist Fermion bound states around skyrmions. For each sublattice, there exist induced fractional fermion numbers around the skyrmions. The total induced fermion number is zero due to the "cancelling effect" between two sublattices with opposite charges.
Quantum Hall Effect of Massless Dirac Fermions and Free Fermions in Hofstadter's Butterfly
Yoshioka, Nobuyuki; Matsuura, Hiroyasu; Ogata, Masao
2016-06-01
We propose a new physical interpretation of the Diophantine equation of σxy for the Hofstadter problem. First, we divide the energy spectrum, or Hofstadter's butterfly, into smaller self-similar areas called "subcells", which were first introduced by Hofstadter to describe the recursive structure. We find that in the energy gaps between subcells, there are two ways to account for the quantization rule of σxy, that are consistent with the Diophantine equation: Landau quantization of (i) massless Dirac fermions or (ii) free fermions in Hofstadter's butterfly.
On the trace anomaly of a Weyl fermion
Bastianelli, Fiorenzo
2016-01-01
We calculate the trace anomaly of a Weyl fermion coupled to gravity by using Fujikawa's method supplemented by a consistent regulator. The latter is constructed out of Pauli-Villars regulating fields. The motivation for presenting such a calculation stems from recent studies that suggest that the trace anomaly of chiral fermions in four dimensions might contain an imaginary part proportional to the Pontryagin density. We find that the trace anomaly of a Weyl fermion is given by half the trace anomaly of a Dirac fermion, so that no imaginary part proportional to the Pontryagin density is seen to arise.
On the polarization of fermion in an intermediate state
Kaloshin, A E
2016-01-01
We show that calculation of a scattered fermion polarization (for a pure initial state) is equivalent to the problem of looking for complete polarization axis of bispinor. This gives the method for calculation of polarization applicable for both final and intermediate state fermions. We suggest to use fermion propagator (bare or dressed) in form of spectral representation, which gives the orthogonal off-shell energy projectors. This representation leads to covariant separation of particle and antiparticle contributions and gives a natural definition for polarization of intermediate state fermion.
Wilson fermions and axion electrodynamics in optical lattices.
Bermudez, A; Mazza, L; Rizzi, M; Goldman, N; Lewenstein, M; Martin-Delgado, M A
2010-11-05
We show that ultracold Fermi gases in optical superlattices can be used as quantum simulators of relativistic lattice fermions in 3+1 dimensions. By exploiting laser-assisted tunneling, we find an analogue of the so-called naive Dirac fermions, and thus provide a realization of the fermion doubling problem. Moreover, we show how to implement Wilson fermions, and discuss how their mass can be inverted by tuning the laser intensities. In this regime, our atomic gas corresponds to a phase of matter where Maxwell electrodynamics is replaced by axion electrodynamics: a 3D topological insulator.
Fermion frontiers in vector lattice gauge theories: Proceedings. Volume 8
Energy Technology Data Exchange (ETDEWEB)
NONE
1998-11-01
The inclusion of fermions into simulations of lattice gauge theories is very difficult both theoretically and numerically. With the presence of Teraflops-scale computers for lattice gauge theory, the authors wanted a forum to discuss new approaches to lattice fermions. The workshop concentrated on approaches which are ripe for study on such large machines. Although lattice chiral fermions are vitally important to understand, there is not technique at hand which is viable on these Teraflops-scale machines for real-world problems. The discussion was therefore focused on recent developments and future prospects for QCD-like theories. For the well-known fermion formulations, the Aoki phase in Wilson fermions, novelties of U{sub A}(1) symmetry and the {eta}{prime} for staggered fermions and new approaches for simulating the determinant for Wilson fermions were discussed. The newer domain-wall fermion formulation was reviewed, with numerical results given by many speakers. The fermion proposal of Friedberg, Lee and Pang was introduced. They also were able to compare and contrast the dependence of QCD and QCD-like SUSY theories on the number of quark flavors. These proceedings consist of several transparencies and a summary page from each speaker. This should serve to outline the major points made in each talk.
Unpaired Composite Fermion, Topological Exciton, and Zero Mode
Sreejith, G. J.; Wójs, A.; Jain, J. K.
2011-09-01
The paired state of composite fermions is expected to support two kinds of excitations: vortices and unpaired composite fermions. We construct an explicit microscopic description of the unpaired composite fermions, which we demonstrate to be accurate for a 3-body model interaction and, possibly, adiabatically connected to the Coulomb solution. This understanding reveals that an unpaired composite fermion carries with it a charge-neutral “topological” exciton, which, in turn, helps provide microscopic insight into the origin of zero modes, fusion rules, and energetics.
Calculation of CWKB envelope in boson and fermion productions
Indian Academy of Sciences (India)
S Biswas; I Chowdhury
2007-01-01
We present the calculation of envelope of boson and of both low- and high- mass fermion production at the end of inflation when the coherently oscillating inflatons decay into bosons and fermions. We consider three different models of inflation and use CWKB technique to calculate the envelope to understand the structure of resonance band formation. We observe that though low-mass fermion production is not effective in pre-heating because of Pauli blocking, it is quite probable for high-mass fermion to take part in pre-heating.
Novel phases in strongly coupled four-fermion theories
Catterall, Simon
2016-01-01
We study a lattice model comprising four flavors of reduced staggered fermion in four dimensions interacting via a specific four-fermion interaction. We present both theoretical arguments and numerical evidence that support the idea that the system develops a mass gap for sufficiently strong four-fermi coupling via the formation of a symmetric four-fermion condensate. In contrast to other lattice four-fermion models studied previously our results do {\\it not} favor the formation of a symmetry-breaking bilinear condensate for any value of the four-fermi coupling and we find evidence for one or more {\\it continuous} phase transitions separating the weak and strong coupling regimes.
Constraints on dark matter annihilation to fermions and a photon
Chowdhury, Debtosh; Laha, Ranjan
2016-01-01
We consider Majorana dark matter annihilation to fermion - anti-fermion pair and a photon in the effective field theory paradigm, by introducing dimension 6 and dimension 8 operators in the Lagrangian. For a given value of the cut-off scale, the latter dominates the annihilation process for heavier dark matter masses. We find a cancellation in the dark matter annihilation to a fermion - anti-fermion pair when considering the interference of the dimension 6 and the dimension 8 operators. Constraints on the effective scale cut-off is derived while considering indirect detection experiments and the relic density requirements and then comparing them to the bound coming from collider experiments.
Orbital magnetization of interacting Dirac fermions in graphene
Yan, Xin-Zhong; Ting, C. S.
2017-09-01
We present a formalism to calculate the orbital magnetization of interacting Dirac fermions under a magnetic field. In this approach, the divergence difficulty is overcome with a special limit of the derivative of the thermodynamic potential with respect to the magnetic field. The formalism satisfies the particle-hole symmetry of the Dirac fermions system. We apply the formalism to the interacting Dirac fermions in graphene. The charge and spin orderings and the exchange interactions between all the Landau levels are taken into account by the mean-field theory. The results for the orbital magnetization of interacting Dirac fermions are compared with that of noninteracting cases.
Strongly Interacting Fermions in Optical Lattices
Koetsier, A. O.
2009-07-01
This thesis explores certain extraordinary phenomena that occur when a gas of neutral atoms is cooled to the coldest temperatures in the universe --- much colder, in fact, than the electromagnetic radiation that permeates the vacuum of interstellar space. At those extreme temperatures, quantum effects dominate and the collective behaviour of the atoms can have unexpected consequences. For example, Bose-Einstein condensation may occur where the atoms lose their individual identities to coalesce into a macroscopic quantum particle. Although such ultracold atomic gases are interesting in their own right, much of the excitement generated in this field is due to the possibility that studying these gases could shed light on intractable problems in other areas of physics. This is predominantly due to the uniquely high degree of control over various physical parameters that ultracold atomic gases afford to experimentalists. Recent technological advances exploit this advantage to study quantum phenomena in a detail that would not be possible in other systems. For instance, atoms can be made to attract or repel each other, the strength of this interaction can be set to almost any value, and external potentials of various geometries and periodicities can be introduced. In this way, atoms can be used to model phenomena as diverse as the quark-gluon plasmas arising in high-energy particle physics, the colour superfluids conjectured to exist in the core of neutron stars, and the high-temperature superconductivity exhibited by electrons on the ion lattice of certain compounds. Indeed, ultracold atomic gases also have a demonstrated applicability to quantum information and computation. Due to a subtle interplay between electronic and nuclear spins known as the hyperfine interaction, atoms can have either an integer or half-integer total spin quantum number, making them either bosonic or fermionic at low temperatures, respectively. With the exception of chapter 7, the work
Fermionic realisations of simple Lie algebras and their invariant fermionic operators
Azcarraga, J A D
2000-01-01
We study the representation D of a simple compact Lie algebra g of rank l constructed with the aid of the hermitian Dirac matrices of a ( dim g )-dimensional euclidean space. The irreducible representations of g contained in D are found by providing a general construction on suitable fermionic Fock spaces. We give full details not only for the simplest odd and even cases, namely su(2) and su(3) , but also for the next ( dim g )-even case of su(5) . Our results are far reaching: they apply to any g -invariant quantum mechanical system containing dim g fermions. Another reason for undertaking this study is to examine the role of the g -invariant fermionic operators that naturally arise. These are given in terms of products of an odd number of gamma matrices, and include, besides a cubic operator, l-1 fermionic scalars of higher order. The latter are constructed from the Lie algebra cohomology cocycles, and must be considered to be of theoretical significance similar to the cubic operator. In the ( dim g )-even ...
Two dimensional fermions in three dimensional YM
Narayanan, R
2010-01-01
Dirac fermions in the fundamental representation of $SU(N)$ live on the surface of a cylinder embedded in $R^3$ and interact with a three dimensional $SU(N)$ Yang Mills vector potential preserving a global chiral symmetry at finite $N$. As the circumference of the cylinder is varied from small to large, the chiral symmetry gets spontaneously broken in the infinite $N$ limit at a typical bulk scale. Replacing three dimensional YM by four dimensional YM introduces non-trivial renormalization effects.
Universal fermionic spectral functions from string theory.
Gauntlett, Jerome P; Sonner, Julian; Waldram, Daniel
2011-12-09
We carry out the first holographic calculation of a fermionic response function for a strongly coupled d=3 system with an explicit D=10 or D=11 supergravity dual. By considering the supersymmetry current, we obtain a universal result applicable to all d=3 N=2 SCFTs with such duals. Surprisingly, the spectral function does not exhibit a Fermi surface, despite the fact that the system is at finite charge density. We show that it has a phonino pole and at low frequencies there is a depletion of spectral weight with a power-law scaling which is governed by a locally quantum critical point.
Strong coupling effective theory with heavy fermions
Fromm, Michael; Lottini, Stefano; Philipsen, Owe
2011-01-01
We extend the recently developed strong coupling, dimensionally reduced Polyakov-loop effective theory from finite-temperature pure Yang-Mills to include heavy fermions and nonzero chemical potential by means of a hopping parameter expansion. Numerical simulation is employed to investigate the weakening of the deconfinement transition as a function of the quark mass. The tractability of the sign problem in this model is exploited to locate the critical surface in the (M/T, mu/T, T) space over the whole range of chemical potentials from zero up to infinity.
Fermion confinement by a relativistic flux tube
Olsson, M G; Williams, K; Olsson, M G; Veseli, S; Williams, K
1996-01-01
We formulate the description of the dynamic confinement of a single fermion by a flux tube. The range of validity extends from the relativistic corrections of a slowly moving quark to the ultra-relativistic motion in a heavy-light meson. The reduced Salpeter equation, also known as the no-pair equation, provides the framework for our discussion. The Regge structure is that of a Nambu string with one end fixed. Numerical solutions are found giving very good fits to heavy-light meson masses. The Isgur-Wise function with a zero recoil slope of \\xi'(1)\\simeq -1.23 is obtained.
Some Improved Nonperturbative Bounds for Fermionic Expansions
Energy Technology Data Exchange (ETDEWEB)
Lohmann, Martin, E-mail: marlohmann@gmail.com [Universita di Roma Tre, Dipartimento di Matematica (Italy)
2016-06-15
We reconsider the Gram-Hadamard bound as it is used in constructive quantum field theory and many body physics to prove convergence of Fermionic perturbative expansions. Our approach uses a recursion for the amplitudes of the expansion, discovered in a model problem by Djokic (2013). It explains the standard way to bound the expansion from a new point of view, and for some of the amplitudes provides new bounds, which avoid the use of Fourier transform, and are therefore superior to the standard bounds for models like the cold interacting Fermi gas.
Van Hove correlation functions for identical fermions
Macke, Wilhelm; Miesenböck, Helga M.; Hingerl, Kurt; Bachlechner, Martina E.
1989-02-01
For a quantum system of identical fermions a partition of the density-density correlation function in its ``self'' and ``distinct'' part is presented. These quantities show different properties than their classical counterparts, e.g., they violate the ``detailed balance'' and are not necessarily real. Nevertheless it can be expected that they will provide a good tool for a better description of the self-motion in many-particle systems and are therefore investigated in second-order perturbation theory of the interparticle potential.
Dimensional Hierarchy of Fermionic Interacting Topological Phases
Queiroz, Raquel; Khalaf, Eslam; Stern, Ady
2016-11-01
We present a dimensional reduction argument to derive the classification reduction of fermionic symmetry protected topological phases in the presence of interactions. The dimensional reduction proceeds by relating the topological character of a d -dimensional system to the number of zero-energy bound states localized at zero-dimensional topological defects present at its surface. This correspondence leads to a general condition for symmetry preserving interactions that render the system topologically trivial, and allows us to explicitly write a quartic interaction to this end. Our reduction shows that all phases with topological invariant smaller than n are topologically distinct, thereby reducing the noninteracting Z classification to Zn.