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Sample records for nuclear landau-zener effect

  1. Landau-Zener-Stueckelberg interferometry

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    Shevchenko, S.N., E-mail: sshevchenko@ilt.kharkov.u [B.Verkin Institute for Low Temperature Physics and Engineering, Kharkov (Ukraine); RIKEN Advanced Science Institute, Wako-shi, Saitama (Japan); Ashhab, S.; Nori, Franco [RIKEN Advanced Science Institute, Wako-shi, Saitama (Japan); Department of Physics, The University of Michigan, Ann Arbor, MI (United States)

    2010-07-15

    A transition between energy levels at an avoided crossing is known as a Landau-Zener transition. When a two-level system (TLS) is subject to periodic driving with sufficiently large amplitude, a sequence of transitions occurs. The phase accumulated between transitions (commonly known as the Stueckelberg phase) may result in constructive or destructive interference. Accordingly, the physical observables of the system exhibit periodic dependence on the various system parameters. This phenomenon is often referred to as Landau-Zener-Stueckelberg (LZS) interferometry. Phenomena related to LZS interferometry occur in a variety of physical systems. In particular, recent experiments on LZS interferometry in superconducting TLSs (qubits) have demonstrated the potential for using this kind of interferometry as an effective tool for obtaining the parameters characterizing the TLS as well as its interaction with the control fields and with the environment. Furthermore, strong driving could allow for fast and reliable control of the quantum system. Here we review recent experimental results on LZS interferometry, and we present related theory.

  2. Landau-Zener-Stueckelberg interferometry

    International Nuclear Information System (INIS)

    Shevchenko, S.N.; Ashhab, S.; Nori, Franco

    2010-01-01

    A transition between energy levels at an avoided crossing is known as a Landau-Zener transition. When a two-level system (TLS) is subject to periodic driving with sufficiently large amplitude, a sequence of transitions occurs. The phase accumulated between transitions (commonly known as the Stueckelberg phase) may result in constructive or destructive interference. Accordingly, the physical observables of the system exhibit periodic dependence on the various system parameters. This phenomenon is often referred to as Landau-Zener-Stueckelberg (LZS) interferometry. Phenomena related to LZS interferometry occur in a variety of physical systems. In particular, recent experiments on LZS interferometry in superconducting TLSs (qubits) have demonstrated the potential for using this kind of interferometry as an effective tool for obtaining the parameters characterizing the TLS as well as its interaction with the control fields and with the environment. Furthermore, strong driving could allow for fast and reliable control of the quantum system. Here we review recent experimental results on LZS interferometry, and we present related theory.

  3. Landau-Zener-Stückelberg Interferometry of a Single Electronic Spin in a Noisy Environment

    Directory of Open Access Journals (Sweden)

    Pu Huang

    2011-08-01

    Full Text Available We demonstrate quantum coherent control of single electronic spins in a nitron-vacancy center in diamond by exploiting and implementing the general concept of Landau-Zener-Stückelberg interferometry at room temperature. The interferometry manipulates an effective two-level system of electronic spins which are coupled to the nearby ^{14}N nuclear spin in the nitron-vacancy center as well as the nuclear spin bath in the diamond. With a microwave field to control the energy gap between the two levels and an AC field as the time-dependent driving field in Landau-Zener-Stückelberg interferometry, the interference pattern can be generated and controlled by controlling a number of parameters in the fields, corresponding to coherent control of the state of the electronic spins. In particular, the interference pattern is observed oscillating as a function of the frequency of the microwave field. Decays in the visibility of the interference pattern are also observed and well explained by numerical simulation which takes into account the thermal fluctuations arising from the nuclear bath. Therefore, our work also demonstrates that Landau-Zener-Stückelberg interferometry can be used for probing decoherence processes of electronic spins.

  4. Integral definition of transition time in the Landau-Zener model

    International Nuclear Information System (INIS)

    Yan Yue; Wu Biao

    2010-01-01

    We give a general definition for the transition time in the Landau-Zener model. This definition allows us to compute numerically the Landau-Zener transition time at any sweeping rate without ambiguity in both diabatic and adiabatic bases. With this new definition, analytical results are obtained in both the adiabatic limit and the sudden limit.

  5. Spatial Landau-Zener-Stueckelberg interference in spinor Bose-Einstein condensates

    International Nuclear Information System (INIS)

    Zhang, J.-N.; Sun, C.-P.; Yi, S.; Nori, Franco

    2011-01-01

    We investigate the Stueckelberg oscillations of a spin-1 Bose-Einstein condensate subject to a spatially inhomogeneous transverse magnetic field and a periodic longitudinal field. We show that the time-domain Stueckelberg oscillations result in modulations in the density profiles of all spin components due to the spatial inhomogeneity of the transverse field. This phenomenon represents the Landau-Zener-Stueckelberg interference in the space domain. Since the magnetic dipole-dipole interaction between spin-1 atoms induces an inhomogeneous effective magnetic field, interference fringes also appear if a dipolar spinor condensate is driven periodically. We also point out some potential applications of this spatial Landau-Zener-Stuekelberg interference.

  6. Tunable Landau-Zener transitions using continuous- and chirped-pulse-laser couplings

    Science.gov (United States)

    Sarreshtedari, Farrokh; Hosseini, Mehdi

    2017-03-01

    The laser coupled Landau-Zener avoided crossing has been investigated with an aim towards obtaining the laser source parameters for precise controlling of the state dynamics in a two-level quantum system. The conventional Landau-Zener equation is modified for including the interaction of the system with a laser field during a bias energy sweep and the obtained Hamiltonian is numerically solved for the investigation of the two-state occupation probabilities. We have shown that in the Landau-Zener process, using an additional laser source with controlled amplitude, frequency, and phase, the system dynamics could be arbitrarily engineered. This is while, by synchronous frequency sweeping of a chirped-pulse laser, the system could be guided into a resonance condition, which again gives the remarkable possibility for precise tuning and controlling of the quantum system dynamics.

  7. Integrable time-dependent Hamiltonians, solvable Landau-Zener models and Gaudin magnets

    Science.gov (United States)

    Yuzbashyan, Emil A.

    2018-05-01

    We solve the non-stationary Schrödinger equation for several time-dependent Hamiltonians, such as the BCS Hamiltonian with an interaction strength inversely proportional to time, periodically driven BCS and linearly driven inhomogeneous Dicke models as well as various multi-level Landau-Zener tunneling models. The latter are Demkov-Osherov, bow-tie, and generalized bow-tie models. We show that these Landau-Zener problems and their certain interacting many-body generalizations map to Gaudin magnets in a magnetic field. Moreover, we demonstrate that the time-dependent Schrödinger equation for the above models has a similar structure and is integrable with a similar technique as Knizhnik-Zamolodchikov equations. We also discuss applications of our results to the problem of molecular production in an atomic Fermi gas swept through a Feshbach resonance and to the evaluation of the Landau-Zener transition probabilities.

  8. Effects of periodic modulation on the Landau-Zener transition

    International Nuclear Information System (INIS)

    Duan Suqing; Fu Libin; Liu Jie; Zhao Xiangeng

    2005-01-01

    We study the quantum tunnelling of a two-level crossing system which extends the standard Landau-Zener model with applying a periodic modulation on its energy sweep. By directly integrating the time evolution operator we obtain the analytic expressions of tunnelling probability in the cases of high and low modulation frequency limit as well as in weak inter-level coupling limit. Our formula clarify the conditions for resonance occurrence, with the help of it we can readily manipulate the system in a desired way, say, to enhance or suppress the tunnelling probability effectively through adjusting the modulation properly

  9. Landau-Zener transitions and Dykhne formula in a simple continuum model

    Science.gov (United States)

    Dunham, Yujin; Garmon, Savannah

    The Landau-Zener model describing the interaction between two linearly driven discrete levels is useful in describing many simple dynamical systems; however, no system is completely isolated from the surrounding environment. Here we examine a generalizations of the original Landau-Zener model to study simple environmental influences. We consider a model in which one of the discrete levels is replaced with a energy continuum, in which we find that the survival probability for the initially occupied diabatic level is unaffected by the presence of the continuum. This result can be predicted by assuming that each step in the evolution for the diabatic state evolves independently according to the Landau-Zener formula, even in the continuum limit. We also show that, at least for the simplest model, this result can also be predicted with the natural generalization of the Dykhne formula for open systems. We also observe dissipation as the non-escape probability from the discrete levels is no longer equal to one.

  10. Surface Acoustic Bloch Oscillations, the Wannier-Stark Ladder, and Landau-Zener Tunneling in a Solid

    Science.gov (United States)

    de Lima, M. M., Jr.; Kosevich, Yu. A.; Santos, P. V.; Cantarero, A.

    2010-04-01

    We present the experimental observation of Bloch oscillations, the Wannier-Stark ladder, and Landau-Zener tunneling of surface acoustic waves in perturbed grating structures on a solid substrate. A model providing a quantitative description of our experimental observations, including multiple Landau-Zener transitions of the anticrossed surface acoustic Wannier-Stark states, is developed. The use of a planar geometry for the realization of the Bloch oscillations and Landau-Zener tunneling allows a direct access to the elastic field distribution. The vertical surface displacement has been measured by interferometry.

  11. Exact results for survival probability in the multistate Landau-Zener model

    International Nuclear Information System (INIS)

    Volkov, M V; Ostrovsky, V N

    2004-01-01

    An exact formula is derived for survival probability in the multistate Landau-Zener model in the special case where the initially populated state corresponds to the extremal (maximum or minimum) slope of a linear diabatic potential curve. The formula was originally guessed by S Brundobler and V Elzer (1993 J. Phys. A: Math. Gen. 26 1211) based on numerical calculations. It is a simple generalization of the expression for the probability of diabatic passage in the famous two-state Landau-Zener model. Our result is obtained via analysis and summation of the entire perturbation theory series

  12. Landau-Zener-Stueckelberg interferometry with low- and high-frequency driving

    Science.gov (United States)

    Shevchenko, Sergey; Ashhab, Sahel; Nori, Franco

    2010-03-01

    The problem of a periodically driven two-level system cannot be solved exactly. The rotating-wave approximation (RWA) is the most common approximation used to analyze this problem. I will discuss an alternative approximation that applies in the case of very strong driving, where the RWA is generally invalid. The dynamics is approximated by a sequence of Landau-Zener transitions that can interfere constructively or destructively, depending on the Stueckelberg phase accumulated between transitions. It turns out that the resonance conditions are qualitatively different for the cases of low- and high-frequency driving. I will discuss the two respective limits. I will also show that our theoretical results describe recent experiments on Landau-Zener-Stuckelberg interferometry with superconducting qubits [S.N. Shevchenko, S. Ashhab, and F. Nori, arXiv:0911.1917].

  13. Low-frequency Landau-Zener-Stuckelberg interference in dissipative superconducting qubits

    International Nuclear Information System (INIS)

    Du-lingjie; Lan- Dong; Yu-Yang

    2013-01-01

    Landau-Zener-Stuckelberg (LZS) interference of continuously driven superconducting qubits is studied. Going beyond the second order perturbation expansion, we find a time dependent stationary population evolution as well as unsymmetrical microwave driven Landau-Zener transitions, resulting from the nonresonant terms which are neglected in rotating-wave approximation. For the low-frequency driving, the qubit population at equilibrium is a periodical function of time, owing to the contribution of the nonresonant terms. In order to obtain the average population, it is found that the average approximation based on the perturbation approach can be applied to the low-frequency region. For the extremely low frequency which is much smaller than the decoherence rate, we develop noncoherence approximation by dividing the evolution into discrete time steps during which the coherence is lost totally. These approximations present comprehensive analytical descriptions of LZS interference in most of parameter space of frequency and decoherence rate, agreeing well with those of the numerical simulations and providing a simple but integrated understanding to system dynamics. The application of our models to microwave cooling can obtain the minimal frequency to realize effective microwave cooling.

  14. Surface Acoustic Analog of Bloch Oscillations, Wannier-Stark Ladders and Landau-Zener Tunneling

    Science.gov (United States)

    de Lima, M. M.; Kosevich, Yu. A.; Santos, P. V.; Cantarero, A.

    2011-12-01

    In this contribution, we discuss the recent experimental demonstration of Wannier-Stark ladders, Bloch Oscillations and Landau Zener tunneling in a solid by means of surface acoustic waves propagating through perturbed grating structures.

  15. The Simplest Quantum Model Supporting the Kibble-Zurek Mechanism of Topological Defect Production: Landau-Zener Transitions from a New Perspective

    International Nuclear Information System (INIS)

    Damski, Bogdan

    2005-01-01

    It can be shown that the dynamics of the Landau-Zener model can be accurately described in terms of the Kibble-Zurek theory of the topological defect production in nonequilibrium phase transitions. The simplest quantum model exhibiting the Kibble-Zurek mechanism is presented. A new intuitive description of Landau-Zener dynamics is found

  16. Definite evidence of the Landau-Zener transition in nucleus-nucleus collisions

    International Nuclear Information System (INIS)

    Imanishi, B.; Oertzen, W. von; Voit, H.

    1986-05-01

    It is shown that the Landau-Zener transition mechanism due to the formation of molecular orbitals of the active neutron exists in the inelastic scattering 13 C( 12 C, 12 C) 13 C* (3.086 MeV, 1/2 + ). The evidence stems from characteristic changes of the angular distributions observed as function of the incident energy. (author)

  17. Quantum driving protocols for a two-level system: From generalized Landau-Zener sweeps to transitionless control

    DEFF Research Database (Denmark)

    Malossi, Nicola; Bason, Mark George; Viteau, Matthieu

    2013-01-01

    We present experimental results on the preparation of a desired quantum state in a two-level system with the maximum possible fidelity using driving protocols ranging from generalizations of the linear Landau-Zener protocol to transitionless driving protocols that ensure perfect following of the ...

  18. Gyrotropic Zener tunneling and nonlinear IV curves in the zero-energy Landau level of graphene in a strong magnetic field.

    Science.gov (United States)

    Laitinen, Antti; Kumar, Manohar; Hakonen, Pertti; Sonin, Edouard

    2018-01-12

    We have investigated tunneling current through a suspended graphene Corbino disk in high magnetic fields at the Dirac point, i.e. at filling factor ν = 0. At the onset of the dielectric breakdown the current through the disk grows exponentially before ohmic behaviour, but in a manner distinct from thermal activation. We find that Zener tunneling between Landau sublevels dominates, facilitated by tilting of the source-drain bias potential. According to our analytic modelling, the Zener tunneling is strongly affected by the gyrotropic force (Lorentz force) due to the high magnetic field.

  19. Weak coupling polaron and Landau-Zener scenario: Qubits modeling

    Science.gov (United States)

    Jipdi, M. N.; Tchoffo, M.; Fokou, I. F.; Fai, L. C.; Ateuafack, M. E.

    2017-06-01

    The paper presents a weak coupling polaron in a spherical dot with magnetic impurities and investigates conditions for which the system mimics a qubit. Particularly, the work focuses on the Landau-Zener (LZ) scenario undergone by the polaron and derives transition coefficients (transition probabilities) as well as selection rules for polaron's transitions. It is proven that, the magnetic impurities drive the polaron to a two-state superposition leading to a qubit structure. We also showed that the symmetry deficiency induced by the magnetic impurities (strong magnetic field) yields to the banishment of transition coefficients with non-stacking states. However, the transition coefficients revived for large confinement frequency (or weak magnetic field) with the orbital quantum numbers escorting transitions. The polaron is then shown to map a qubit independently of the number of relevant states with the transition coefficients lifted as LZ probabilities and given as a function of the electron-phonon coupling constant (Fröhlich constant).

  20. Nuclear Landau-Zener phenomena and the fusion cross sections in the system 13C + 16O → 12C + 17O

    International Nuclear Information System (INIS)

    Imanishi, B.; Oertzen, W. von.

    1990-07-01

    Reaction mechanism of the system 13 C+ 16 O- 12 C+ 17 O is investigated with the use of the nucleon molecular-orbital model in the framework of the orthogonalized coupled-reaction-channel (OCRC) theory. The adiabatic potentials obtained are quite different from the diagonal potentials of the original OCRC basis. The Landau-Zener radial coupling explains the backward enhancement of measured differential cross sections of the transfer reaction 13 C( 16 O, 17 O) 12 C. In the OCRC calculation the fusion cross sections of the channel 13 C+ 16 O is enhanced at low bombarding energies, in agreement with the experimental data. (author)

  1. Manipulation of the spin in single molecule magnets via Landau-Zener transitions

    Science.gov (United States)

    Palii, Andrew; Tsukerblat, Boris; Clemente-Juan, Juan M.; Gaita-Ariño, Alejandro; Coronado, Eugenio

    2011-11-01

    We theoretically investigate the effects of a magnetic pulse on a single-molecule magnet (SMM) initially magnetized by a dc field along the easy axis of magnetization. In the Landau-Zener (LZ) scheme, it is shown that the final spin state is a function of the shape and duration of the pulse, conditioned by the decoherence time of the SMM. In the case of coherent tunneling, the asymmetric pulses are shown to reverse the direction of the magnetization, while the symmetric pulses can only decrease the value of the initial magnetization. It is also demonstrated that the application of an external variable dc field in the hard plane of magnetization provides the possibility to tune the resulting magnetization due to quantum interference effects. The results and the conditions for the observation of the pulse-triggered LZ transitions are illustrated by the application of the proposed scheme to the well-studied single-molecule magnet Fe8. To put the results into perspective, some potential applications of SMMs experiencing pulse-induced LZ transitions, such as switching devices and qubits, are discussed.

  2. Mean-field dynamics of a Bose-Einstein condensate in a time-dependent triple-well trap: Nonlinear eigenstates, Landau-Zener models, and stimulated Raman adiabatic passage

    International Nuclear Information System (INIS)

    Graefe, E. M.; Korsch, H. J.; Witthaut, D.

    2006-01-01

    We investigate the dynamics of a Bose-Einstein condensate in a triple-well trap in a three-level approximation. The interatomic interactions are taken into account in a mean-field approximation (Gross-Pitaevskii equation), leading to a nonlinear three-level model. Additional eigenstates emerge due to the nonlinearity, depending on the system parameters. Adiabaticity breaks down if such a nonlinear eigenstate disappears when the parameters are varied. The dynamical implications of this loss of adiabaticity are analyzed for two important special cases: A three-level Landau-Zener model and the stimulated Raman adiabatic passage (STIRAP) scheme. We discuss the emergence of looped levels for an equal-slope Landau-Zener model. The Zener tunneling probability does not tend to zero in the adiabatic limit and shows pronounced oscillations as a function of the velocity of the parameter variation. Furthermore we generalize the STIRAP scheme for adiabatic coherent population transfer between atomic states to the nonlinear case. It is shown that STIRAP breaks down if the nonlinearity exceeds the detuning

  3. Inverse Landau-Zener-Stuckelberg interferometry for the measurement of a resonator's state using a qubit

    Science.gov (United States)

    Shevchenko, Sergey; Ashhab, Sahel; Nori, Franco

    2013-03-01

    We consider theoretically a superconducting qubit - nanomechanical resonator system, which was realized recently by LaHaye et al. [Nature 459, 960 (2009)]. We formulate and solve the inverse Landau-Zener-Stuckelberg problem, where we assume the driven qubit's state to be known (i.e. measured by some other device) and aim to find the parameters of the qubit's Hamiltonian. In particular, for our system the qubit's bias is defined by the nanomechanical resonator's displacement. This may provide a tool for monitoring the nanomechanical resonator 's position. [S. N. Shevchenko, S. Ashhab, and F. Nori, Phys. Rev. B 85, 094502 (2012).

  4. Landau and modern physics

    International Nuclear Information System (INIS)

    Pokrovsky, Valery L

    2009-01-01

    This article describes the history of the creation and further development of Landau's famous works on phase transitions, diamagnetism of electron gas (Landau levels), and quantum transitions at a level crossing (the Landau-Zener phenomenon), and its role in modern physics. (methodological notes)

  5. Landau-Zener evolution under weak measurement: manifestation of the Zeno effect under diabatic and adiabatic measurement protocols

    Science.gov (United States)

    Novelli, Anna; Belzig, Wolfgang; Nitzan, Abraham

    2015-01-01

    The time evolution and the asymptotic outcome of a Landau-Zener-Stueckelberg-Majorana (LZ) process under continuous weak non-selective measurement is analyzed. We compare two measurement protocols in which the populations of either the adiabatic or the non-adiabatic levels are (continuously and weakly) monitored. The weak measurement formalism, described using a Gaussian Kraus operator, leads to a time evolution characterized by a Markovian dephasing process, which, in the non-adiabatic measurement protocol is similar to earlier studies of LZ dynamics in a dephasing environment. Casting the problem in the language of measurement theory makes it possible for us to compare diabatic and adiabatic measurement scenarios, to consider engineered dephasing as a control device and to examine the manifestation of the Zeno effect under the different measurement protocols. In particular, under measurement of the non-adiabatic populations, the Zeno effect is manifested not as a freezing of the measured system in its initial state, but rather as an approach to equal asymptotic populations of the two diabatic states. This behavior can be traced to the way by which the weak measurement formalism behaves in the strong measurement limit, with a built-in relationship between measurement time and strength.

  6. Time-dependent occupation numbers in reduced-density-matrix-functional theory: Application to an interacting Landau-Zener model

    International Nuclear Information System (INIS)

    Requist, Ryan; Pankratov, Oleg

    2011-01-01

    We prove that if the two-body terms in the equation of motion for the one-body reduced density matrix are approximated by ground-state functionals, the eigenvalues of the one-body reduced density matrix (occupation numbers) remain constant in time. This deficiency is related to the inability of such an approximation to account for relative phases in the two-body reduced density matrix. We derive an exact differential equation giving the functional dependence of these phases in an interacting Landau-Zener model and study their behavior in short- and long-time regimes. The phases undergo resonances whenever the occupation numbers approach the boundaries of the interval [0,1]. In the long-time regime, the occupation numbers display correlation-induced oscillations and the memory dependence of the functionals assumes a simple form.

  7. Selective-field-ionization dynamics of a lithium m=2 Rydberg state: Landau-Zener model versus quantal approach

    International Nuclear Information System (INIS)

    Foerre, M.; Hansen, J.P.

    2003-01-01

    The selective-field-ionization (SFI) dynamics of a Rydberg state of lithium with magnetic quantum number m=2 is studied in detail based on two different theoretical models: (1) a close coupling integration of the Schroedinger equation and (2) the multichannel (incoherent) Landau-Zener (MLZ) model. The m=2 states are particularly interesting, since they define a border zone between fully adiabatic (m=0,1) and fully diabatic (m>2) ionization dynamics. Both sets of calculations are performed up to, and above, the classical ionization limit. It is found that the MLZ model is excellent in the description of the fully diabatic dynamics while certain discrepancies between the time dependent quantal amplitudes appear when the dynamics become involved. Thus, in this region, the analysis of experimental SFI spectra should be performed with care

  8. Landau parameters for finite range density dependent nuclear interactions

    International Nuclear Information System (INIS)

    Farine, M.

    1997-01-01

    The Landau parameters represent the effective particle-hole interaction at Fermi level. Since between the physical observables and the Landau parameters there is a direct relation their derivation from an effective interaction is of great interest. The parameter F 0 determines the incompressibility K of the system. The parameter F 1 determines the effective mass (which controls the level density at the Fermi level). In addition, F 0 ' determines the symmetry energy, G 0 the magnetic susceptibility, and G 0 ' the pion condensation threshold in nuclear matter. This paper is devoted to a general derivation of Landau parameters for an interaction with density dependent finite range terms. Particular carefulness is devoted to the inclusion of rearrangement terms. This report is part of a larger project which aims at defining a new nuclear interaction improving the well-known D1 force of Gogny et al. for describing the average nuclear properties and exotic nuclei and satisfying, in addition, the sum rules

  9. Application of the Landau-Zener-Stückelberg-Majorana dynamics to the electrically driven flip of a hole spin

    Science.gov (United States)

    Pasek, W. J.; Maialle, M. Z.; Degani, M. H.

    2018-03-01

    An idea of employing the Landau-Zener-Stückelberg-Majorana dynamics to flip a spin of a single ground state hole is introduced and explored by a time-dependent simulation. This configuration interaction study considers a hole confined in a quantum molecule formed in an InSb 〈111 〉 quantum wire by application of an electrostatic potential. An up-down spin-mixing avoided crossing is formed by nonaxial terms in the Kohn-Luttinger Hamiltonian and the Dresselhaus spin-orbit one. Manipulation of the system is possible by the dynamic change of an external vertical electric field, which enables the consecutive driving of the hole through two anticrossings. Moreover, a simple model of the power-law-type noise that impedes precise electric control of the system is included in the form of random telegraph noise to estimate the limitations of the working conditions. We show that in principle the process is possible, but it requires precise control of the parameters of the driving impulse.

  10. Landau-Zener tunneling in the presence of weak intermolecular interactions in a crystal of Mn4 single-molecule magnets

    Science.gov (United States)

    Wernsdorfer, W.; Bhaduri, S.; Vinslava, A.; Christou, G.

    2005-12-01

    A Mn4 single-molecule magnet (SMM), with a well-isolated spin ground state of S=9/2 , is used as a model system to study Landau-Zener (LZ) tunneling in the presence of weak intermolecular dipolar and exchange interactions. The anisotropy constants D and B are measured with minor hysteresis loops. A transverse field is used to tune the tunnel splitting over a large range. Using the LZ and inverse LZ method, it is shown that these interactions play an important role in the tunnel rates. Three regions are identified: (i) at small transverse fields, tunneling is dominated by single tunnel transitions, (ii) at intermediate transverse fields, the measured tunnel rates are governed by reshuffling of internal fields, and (iii) at larger transverse fields, the magnetization reversal starts to be influenced by the direct relaxation process, and many-body tunnel events may occur. The hole digging method is used to study the next-nearest-neighbor interactions. At small external fields, it is shown that magnetic ordering occurs which does not quench tunneling. An applied transverse field can increase the ordering rate. Spin-spin cross-relaxations, mediated by dipolar and weak exchange interactions, are proposed to explain additional quantum steps.

  11. Quantum system driven by incoherent a.c fields: Multi-crossing Landau Zener dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Jipdi, M.N., E-mail: jmichaelnicky@yahoo.fr; Fai, L.C.; Tchoffo, M.

    2016-10-23

    The paper investigates the multi-crossing dynamics of a Landau–Zener (LZ) system driven by two sinusoidal a.c fields applying the Dynamic Matrix approach (DMA). The system is shown to follow one-crossing and multi-crossing dynamics for low and high frequency regime respectively. It is shown that in low frequency regime, the resonance phenomenon occurs and leads to the decoupling of basis states; the effective gap vanishes and then the complete blockage of the system. For high frequency, the system achieves multi-crossing dynamics with two fictitious crossings; the system models a Landau–Zener–Stückelberg (LZS) interferometer with critical parameters that tailor probabilities. The system is then shown to depend only on the phase that permits the easiest control with possible application in implementing logic gates.

  12. Dynamic nuclear polarization at high Landau levels in a quantum point contact

    Science.gov (United States)

    Fauzi, M. H.; Noorhidayati, A.; Sahdan, M. F.; Sato, K.; Nagase, K.; Hirayama, Y.

    2018-05-01

    We demonstrate a way to polarize and detect nuclear spin in a gate-defined quantum point contact operating at high Landau levels. Resistively detected nuclear magnetic resonance (RDNMR) can be achieved up to the fifth Landau level and at a magnetic field lower than 1 T. We are able to retain the RDNMR signals in a condition where the spin degeneracy of the first one-dimensional (1D) subband is still preserved. Furthermore, the effects of orbital motion on the first 1D subband can be made smaller than those due to electrostatic confinement. This developed RDNMR technique is a promising means to study electronic states in a quantum point contact near zero magnetic field.

  13. Isoscalar giant resonances and Landau parameters with density-dependent effective interactions

    International Nuclear Information System (INIS)

    Kohno, Michio; Ando, Kazuhiko

    1979-01-01

    Discussion is given on the relations between the Landau parameters and the isoscalar giant (quadrupole- and monopole-) resonance energies by using general density-dependent interactions. In the limit of infinite nuclear matter, the isoscalar giant quadrupole energy is shown to depend not only on the effective mass but also on the Landau parameter F 2 . Collective energies of the isoscalar giant resonances are calculated for 16 O and 40 Ca with four different effective interactions, G-0, B1, SII and SV, by using the scaling- and constrained Hartree-Fock-methods. It is shown that the dependence of the collective energies on the effective interactions is essentially determined by the Landau parameters. The G-0 force is found to be most successful in reproducing the giant resonance energies. Validity of the RPA-moment theorems is examined for the case of local density-dependent interactions. (author)

  14. Nuclear spin bath effects in molecular nanomagnets: Direct quantum mechanical simulations

    Science.gov (United States)

    Sinitsyn, N. A.; Dobrovitski, V. V.

    2004-11-01

    We investigate the influence of nuclear spins on the electronic spin tunneling in magnetic molecules such as Fe8 , focusing on the role of the spin diffusion in the nuclear spin bath. We simulate the quantum spin dynamics by numerically solving the time-dependent Schrödinger equation for the compound system (the electronic spin plus the bath spins). Our results demonstrate that the effect of the spin bath cannot always be modeled as a randomly varying magnetic field acting on the electronic spin. We consider two dynamical regimes: the spin relaxation in a constant magnetic field, and the spin tunneling in the linearly varying magnetic field passing the avoided level crossing, so-called Landau-Zener-Stückelberg (LZS) transition. For the first regime, we confirmed that the hole in the magnetization distribution has the width of the hyperfine fields distribution. For the second regime, we found that the transition probability for moderately slow sweeps deviates from the standard LZS prediction, while for the fast sweeps the deviation is negligible.

  15. Theory for cross effect dynamic nuclear polarization under magic-angle spinning in solid state nuclear magnetic resonance: the importance of level crossings.

    Science.gov (United States)

    Thurber, Kent R; Tycko, Robert

    2012-08-28

    We present theoretical calculations of dynamic nuclear polarization (DNP) due to the cross effect in nuclear magnetic resonance under magic-angle spinning (MAS). Using a three-spin model (two electrons and one nucleus), cross effect DNP with MAS for electron spins with a large g-anisotropy can be seen as a series of spin transitions at avoided crossings of the energy levels, with varying degrees of adiabaticity. If the electron spin-lattice relaxation time T(1e) is large relative to the MAS rotation period, the cross effect can happen as two separate events: (i) partial saturation of one electron spin by the applied microwaves as one electron spin resonance (ESR) frequency crosses the microwave frequency and (ii) flip of all three spins, when the difference of the two ESR frequencies crosses the nuclear frequency, which transfers polarization to the nuclear spin if the two electron spins have different polarizations. In addition, adiabatic level crossings at which the two ESR frequencies become equal serve to maintain non-uniform saturation across the ESR line. We present analytical results based on the Landau-Zener theory of adiabatic transitions, as well as numerical quantum mechanical calculations for the evolution of the time-dependent three-spin system. These calculations provide insight into the dependence of cross effect DNP on various experimental parameters, including MAS frequency, microwave field strength, spin relaxation rates, hyperfine and electron-electron dipole coupling strengths, and the nature of the biradical dopants.

  16. Zener diode controls switching of large direct currents

    Science.gov (United States)

    1965-01-01

    High-current zener diode is connected in series with the positive input terminal of a dc supply to block the flow of direct current until a high-frequency control signal is applied across the zener diode. This circuit controls the switching of large dc signals.

  17. Anti-levitation of Landau levels in vanishing magnetic fields

    Science.gov (United States)

    Pan, W.; Baldwin, K. W.; West, K. W.; Pfeiffer, L. N.; Tsui, D. C.

    Soon after the discovery of the quantum Hall effects in two-dimensional electron systems, the question on the fate of the extended states in a Landau level in vanishing magnetic (B) field arose. Many theoretical models have since been proposed, and experimental results remain inconclusive. In this talk, we report experimental observation of anti-levitation behavior of Landau levels in vanishing B fields (down to as low as B 58 mT) in a high quality heterojunction insulated-gated field-effect transistor (HIGFET). We observed that, in the Landau fan diagram of electron density versus magnetic field, the positions of the magneto-resistance minima at Landau level fillings ν = 4, 5, 6 move below the ``traditional'' Landau level line to lower electron densities. This clearly differs from what was observed in the earlier experiments where in the same Landau fan plot the density moved up. Our result strongly supports the anti-levitation behavior predicted recently. Moreover, the even and odd Landau level filling states show quantitatively different behaviors in anti-levitation, suggesting that the exchange interactions, which are important at odd fillings, may play a role. SNL is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energys National Nuclear Security Administration under contract DE-AC04-94AL85000.

  18. Single-particle effects in fine structure of super-asymmetric fission

    International Nuclear Information System (INIS)

    Mirea, M.

    1999-01-01

    Energy spectrum measurements concerning the 14 C decay from 223 Ra revealed a fine structure with an intense branch on the excited state of the daughter 209 Pb. Apart the great number of microscopic--macroscopic attempts of different authors in describing this behavior (compiled recently), this phenomenon was explained quantitatively using the Landau--Zener effect, i.e., the promotion mechanism of a unpaired nucleon between two levels characterised by the same quantum numbers connected to some symmetries of the nuclear system in the region where an avoided level crossing is exhibited. The adiabatic levels during the super-asymmetric fission process were determined with a new version of the two--centre shell model especially constructed for very large mass--asymmetries. The half--lives are obtained in the framework of the Wentzel--Kramers--Brillouin approximation. The amount of the variation of the barrier height in the excited channels was estimated accounting the specialization energy which can be interpreted as the excess of the energy of a nucleon with a given spin over the energy for the same spin nucleon state of lowest energy. It is evidenced that the fine structure of cluster decay is due to two competitive effects: the Landau--Zener effect which enhances the probability to have an excited daughter in the final channel and the specialization energy which increases the potential barrier and therefore leads to a diminution of the penetrability. This formalism was used for predictions of the fine structure in the case of 14 C decay of 225 Ac and to explain the fine structure of alpha decay. (author)

  19. Dual Ginzburg-Landau theory and quark nuclear physics

    International Nuclear Information System (INIS)

    Toki, H.; Suganuma, H.; Ichie, H.; Monden, H.; Umisedo, S.

    1998-01-01

    In quark nuclear physics (QNP), where hadrons and nuclei are described in terms of quarks and gluons, confinement and chiral symmetry breaking are the most fundamental phenomena. The dual Ginzburg-Landau (DGL) theory, which contains monopole fields as the most essential degrees of freedom and their condensation in the vacuum, is able to describe both phenomena. We discuss also the recovery of the chiral symmetry and the deconfinement phase transition at finite temperature in the DGL theory. As for the connection to QCD, we study the instanton configurations in the abelian gauge a la 't Hooft. We find a close connection between instantons and QCD monopoles. We demonstrate also the signature of confinement as the appearance of long monopole trajectories in the MA gauge for the case of dense instanton configurations. (orig.)

  20. Effects of periodic modulation on the nonlinear Landau–Zener tunneling

    International Nuclear Information System (INIS)

    Li-Hua, Wu; Wen-Shan, Duan

    2009-01-01

    We study the Landau–Zener tunneling of a nonlinear two-level system by applying a periodic modulation on its energy bias. We find that the two levels are splitting at the zero points of the zero order Bessel function for high-frequency modulation. Moreover, we obtain the effective coupling constant between two levels at the zero points of the zero order Bessel function by calculating the final tunneling probability at these points. It seems that the effective coupling constant can be regarded as the approximation of the higher order Bessel function at these points. For the low-frequency modulation, we find that the final tunneling probability is a function of the interaction strength. For the weak inter-level coupling case, we find that the final tunneling probability is more disordered as the interaction strength becomes larger. (general)

  1. Dual Ginzburg-Landau theory and quark nuclear physics

    International Nuclear Information System (INIS)

    Toki, Hiroshi

    1999-01-01

    The elementary building blocks of matter are quarks. Hence, it is fundamental to describe hadrons and nuclei in terms of quarks and gluons, the subject of which is called Quark Nuclear Physics. The quark-dynamics is described by Quantum Chromodynamics (QCD). Our interest is the non-perturbative aspect of QCD as confinement, chiral symmetry breaking, hadronization etc. We introduce the dual Ginzburg-Landau theory (DGL), where the color monopole fields and their condensation is the QCD vacuum, play essential roles in describing these non-perturbative phenomena. We emphasize its connection to QCD through the use of the Abelian gauge. We apply the DGL theory to various observables. We discuss then the connection of the monopole fields with instantons, which are the classical solutions of the non-Abelian gauge theory and connect through the tunneling process QCD vacuum with different winding numbers. (author)

  2. Modulation of periodic field on the atomic current in optical lattices with Landau–Zener tunneling considered

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Jie-Yun, E-mail: jyyan@bupt.edu.cn; Wang, Lan-Yu, E-mail: lan_yu_wang@163.com

    2016-09-01

    We investigate the atomic current in optical lattices under the presence of both constant and periodic external field with Landau–Zener tunneling considered. By simplifying the system to a two-band model, the atomic current is obtained based on the Boltzmann equations. We focus on three situations to discuss the influence of the Landau–Zener tunneling and periodic field on the atomic current. Numerical calculations show the atomic transient current would finally become the stable oscillation, whose amplitude and average value can be further adjusted by the periodic external field. It is concluded that the periodic external field could provide an effective modulation on the atomic current even when the Landau–Zener tunneling probability has almostly become a constant.

  3. Explosions in Landau Vlasov dynamics

    International Nuclear Information System (INIS)

    Suraud, E.; Cussol, D.; Gregoire, C.; Boilley, D.; Pi, M.; Schuck, P.; Remaud, B.; Sebille, F.

    1988-01-01

    A microscopic study of the quasi-fusion/explosion transition is presented in the framework of Landau-Vlasov simulations of intermediate energy heavy-ion collisions (bombarding energies between 10 and 100 MeV/A). A detailed analysis in terms of the Equation of State of the system is performed. In agreement with schematic models we find that the composite nuclear system formed in the collision does explode when it stays long enough in the mechanically unstable region (spinodal region). Quantitative estimates of the explosion threshold are given for central symmetric reactions (Ca+Ca and Ar+Ti). The effect of the nuclear matter compressibility modulus is discussed

  4. A novel method of including Landau level mixing in numerical studies of the quantum Hall effect

    International Nuclear Information System (INIS)

    Wooten, Rachel; Quinn, John; Macek, Joseph

    2013-01-01

    Landau level mixing should influence the quantum Hall effect for all except the strongest applied magnetic fields. We propose a simple method for examining the effects of Landau level mixing by incorporating multiple Landau levels into the Haldane pseudopotentials through exact numerical diagonalization. Some of the resulting pseudopotentials for the lowest and first excited Landau levels will be presented

  5. 75 FR 24747 - SCI, LLC/Zener-Rectifier Operations Division A Wholly Owned Subsidiary of SCI, LLC/ON...

    Science.gov (United States)

    2010-05-05

    ... DEPARTMENT OF LABOR Employment and Training Administration [TA-W-70,235] SCI, LLC/Zener-Rectifier... Adjustment Assistance on October 19, 2009, applicable to workers of SCI LLC/Zener-Rectifier, Operations... Technical Resources were employed on-site at the Phoenix Arizona location of SCI LLC/Zener-Rectifier...

  6. Collisional spin-oriented Sherman function in electron-hole semiconductor plasmas: Landau damping effect

    Science.gov (United States)

    Lee, Myoung-Jae; Jung, Young-Dae

    2018-04-01

    The influence of Landau damping on the spin-oriented collisional asymmetry is investigated in electron-hole semiconductor plasmas. The analytical expressions of the spin-singlet and the spin-triplet scattering amplitudes as well as the spin-oriented asymmetry Sherman function are obtained as functions of the scattering angle, the Landau parameter, the effective Debye length, and the collision energy. It is found that the Landau damping effect enhances the spin-singlet and spin-triplet scattering amplitudes in the forward and back scattering domains, respectively. It is also found that the Sherman function increases with an increase in the Landau parameter. In addition, the spin-singlet scattering process is found to be dominant rather than the spin-triplet scattering process in the high collision energy domain.

  7. Rotating effects on the Landau quantization for an atom with a magnetic quadrupole moment

    Energy Technology Data Exchange (ETDEWEB)

    Fonseca, I. C.; Bakke, K., E-mail: kbakke@fisica.ufpb.br [Departamento de Física, Universidade Federal da Paraíba, Caixa Postal 5008, João Pessoa, PB 58051-970 (Brazil)

    2016-01-07

    Based on the single particle approximation [Dmitriev et al., Phys. Rev. C 50, 2358 (1994) and C.-C. Chen, Phys. Rev. A 51, 2611 (1995)], the Landau quantization associated with an atom with a magnetic quadrupole moment is introduced, and then, rotating effects on this analogue of the Landau quantization is investigated. It is shown that rotating effects can modify the cyclotron frequency and breaks the degeneracy of the analogue of the Landau levels.

  8. Rotating effects on the Landau quantization for an atom with a magnetic quadrupole moment

    Science.gov (United States)

    Fonseca, I. C.; Bakke, K.

    2016-01-01

    Based on the single particle approximation [Dmitriev et al., Phys. Rev. C 50, 2358 (1994) and C.-C. Chen, Phys. Rev. A 51, 2611 (1995)], the Landau quantization associated with an atom with a magnetic quadrupole moment is introduced, and then, rotating effects on this analogue of the Landau quantization is investigated. It is shown that rotating effects can modify the cyclotron frequency and breaks the degeneracy of the analogue of the Landau levels.

  9. Rotating effects on the Landau quantization for an atom with a magnetic quadrupole moment

    International Nuclear Information System (INIS)

    Fonseca, I. C.; Bakke, K.

    2016-01-01

    Based on the single particle approximation [Dmitriev et al., Phys. Rev. C 50, 2358 (1994) and C.-C. Chen, Phys. Rev. A 51, 2611 (1995)], the Landau quantization associated with an atom with a magnetic quadrupole moment is introduced, and then, rotating effects on this analogue of the Landau quantization is investigated. It is shown that rotating effects can modify the cyclotron frequency and breaks the degeneracy of the analogue of the Landau levels

  10. Landau damping effects on collision-induced quantum interference in electron-hole plasmas

    International Nuclear Information System (INIS)

    Hwa-Min, Kim; Young-Dae, Jung

    2007-01-01

    The Landau damping effects on the quantum interference in electron collisions are investigated in a quantum plasma composed of electrons and holes. The Born method and the total spin states are considered to obtain the scattering cross-section by using the effective screened potential model. It is found that the Landau damping effects enhance the scattering cross-section, especially, near the scattering angle θ L = π/4. (authors)

  11. Landau damping effects on collision-induced quantum interference in electron-hole plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Hwa-Min, Kim [Daegu Univ. Catholic, Dept. of Electronics Engineering (Korea, Republic of); Young-Dae, Jung [Hanyang Univ., Dept. of Applied Physics, Seoul (Korea, Republic of)

    2007-07-15

    The Landau damping effects on the quantum interference in electron collisions are investigated in a quantum plasma composed of electrons and holes. The Born method and the total spin states are considered to obtain the scattering cross-section by using the effective screened potential model. It is found that the Landau damping effects enhance the scattering cross-section, especially, near the scattering angle {theta}{sub L} = {pi}/4. (authors)

  12. Feasibility study of using a Zener diode as the selection device for bipolar RRAM and WORM memory arrays

    International Nuclear Information System (INIS)

    Li, Yingtao; Fu, Liping; Tao, Chunlan; Jiang, Xinyu; Sun, Pengxiao

    2014-01-01

    Cross-bar arrays are usually used for the high density application of resistive random access memory (RRAM) devices. However, cross-talk interference limits an increase in the integration density. In this paper, the Zener diode is proposed as a selection device to suppress the sneak current in bipolar RRAM arrays. Measurement results show that the Zener diode can act as a good selection device, and the sneak current can be effectively suppressed. The readout margin is sufficiently improved compared to that obtained without the selection device. Due to the improvement for the reading disturbance, the size of the cross-bar array can be enhanced to more than 10 3  × 10 3 . Furthermore, the possibility of using a write-once-read-many-times (WORM) cross-bar array is also demonstrated by connecting the Zener diode and the bipolar RRAM in series. These results strongly suggest that using a Zener diode as a selection device opens up great opportunities to realize high density bipolar RRAM arrays. (paper)

  13. Polarization-induced Zener tunnel diodes in GaN/InGaN/GaN heterojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Xiaodong; Li, Wenjun; Islam, S. M.; Pourang, Kasra; Fay, Patrick [Department of Electrical Engineering, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Xing, Huili; Jena, Debdeep, E-mail: djena@cornell.edu [Department of Electrical Engineering, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Departments of ECE and MSE, Cornell University, Ithaca, New York 14853 (United States)

    2015-10-19

    By the insertion of thin In{sub x}Ga{sub 1−x}N layers into Nitrogen-polar GaN p-n junctions, polarization-induced Zener tunnel junctions are studied. The reverse-bias interband Zener tunneling current is found to be weakly temperature dependent, as opposed to the strongly temperature-dependent forward bias current. This indicates tunneling as the primary reverse-bias current transport mechanism. The Indium composition in the InGaN layer is systematically varied to demonstrate the increase in the interband tunneling current. Comparing the experimentally measured tunneling currents to a model helps identify the specific challenges in potentially taking such junctions towards nitride-based polarization-induced tunneling field-effect transistors.

  14. Polarization-induced Zener tunnel diodes in GaN/InGaN/GaN heterojunctions

    International Nuclear Information System (INIS)

    Yan, Xiaodong; Li, Wenjun; Islam, S. M.; Pourang, Kasra; Fay, Patrick; Xing, Huili; Jena, Debdeep

    2015-01-01

    By the insertion of thin In x Ga 1−x N layers into Nitrogen-polar GaN p-n junctions, polarization-induced Zener tunnel junctions are studied. The reverse-bias interband Zener tunneling current is found to be weakly temperature dependent, as opposed to the strongly temperature-dependent forward bias current. This indicates tunneling as the primary reverse-bias current transport mechanism. The Indium composition in the InGaN layer is systematically varied to demonstrate the increase in the interband tunneling current. Comparing the experimentally measured tunneling currents to a model helps identify the specific challenges in potentially taking such junctions towards nitride-based polarization-induced tunneling field-effect transistors

  15. Impact of Many-Body Effects on Landau Levels in Graphene

    Science.gov (United States)

    Sonntag, J.; Reichardt, S.; Wirtz, L.; Beschoten, B.; Katsnelson, M. I.; Libisch, F.; Stampfer, C.

    2018-05-01

    We present magneto-Raman spectroscopy measurements on suspended graphene to investigate the charge carrier density-dependent electron-electron interaction in the presence of Landau levels. Utilizing gate-tunable magnetophonon resonances, we extract the charge carrier density dependence of the Landau level transition energies and the associated effective Fermi velocity vF. In contrast to the logarithmic divergence of vF at zero magnetic field, we find a piecewise linear scaling of vF as a function of the charge carrier density, due to a magnetic-field-induced suppression of the long-range Coulomb interaction. We quantitatively confirm our experimental findings by performing tight-binding calculations on the level of the Hartree-Fock approximation, which also allow us to estimate an excitonic binding energy of ≈6 meV contained in the experimentally extracted Landau level transitions energies.

  16. Superradiance from crystals of molecular nanomagnets.

    Science.gov (United States)

    Chudnovsky, E M; Garanin, D A

    2002-10-07

    We show that crystals of molecular nanomagnets can exhibit giant magnetic relaxation due to the Dicke superradiance of electromagnetic waves. Rigorous theory is presented that combines superradiance with the Landau-Zener effect.

  17. Dynamical control of matter-wave splitting using time-dependent optical lattices

    DEFF Research Database (Denmark)

    Park, Sung Jong; Andersen, Henrik Kjær; Mai, Sune

    2012-01-01

    We report on measurements of splitting Bose-Einstein condensates (BEC) by using a time-dependent optical lattice potential. First, we demonstrate the division of a BEC into a set of equally populated components by means of time-dependent control of Landau-Zener tunneling in a vertical lattice....... Finally, a combination of multiple Bragg reflections and Landau-Zener tunneling allows for the generation of macroscopic arrays of condensates with potential applications in atom optics and atom interferometry....

  18. SHORT COMMUNICATION: Transportable Zener-diode Voltage Standard

    Science.gov (United States)

    Karpov, O. V.; Shulga, V. M.; Shakirzyanova, F. R.; Sarandi, A. E.

    1994-01-01

    Five transportable Zener-diode dc voltage standards have been developed, fabricated and investigated at the NPO VNIIFTRI. The standards were designed to transfer the unit of electromotive force (emf) from Josephson reference standards to measuring instruments. Following the results of these investigations, standard N 02 has been used for intercomparison of the Russian Josephson reference standards.

  19. Effective Ginzburg–Landau free energy functional for multi-band isotropic superconductors

    International Nuclear Information System (INIS)

    Grigorishin, Konstantin V.

    2016-01-01

    Highlights: • The intergradient coupling of order parameters in a two-band superconductor plays important role and cannot be neglected. • A two-band superconductor must be characterized with a single coherence length and a single Ginzburg–Landau parameter. • Type-1.5 superconductors are impossible. • The free energy functional for a multi-band superconductor can be reduced to the effective single-band Ginzburg–Landau functional. - Abstract: It has been shown that interband mixing of gradients of two order parameters (drag effect) in an isotropic bulk two-band superconductor plays important role – such a quantity of the intergradients coupling exists that the two-band superconductor is characterized with a single coherence length and a single Ginzburg–Landau (GL) parameter. Other quantities or neglecting of the drag effect lead to existence of two coherence lengths and dynamical instability due to violation of the phase relations between the order parameters. Thus so-called type-1.5 superconductors are impossible. An approximate method for solving of set of GL equations for a multi-band superconductor has been developed: using the result about the drag effect it has been shown that the free-energy functional for a multi-band superconductor can be reduced to the GL functional for an effective single-band superconductor.

  20. Charge qubit coupled to an intense microwave electromagnetic field in a superconducting Nb device: evidence for photon-assisted quasiparticle tunneling.

    Science.gov (United States)

    de Graaf, S E; Leppäkangas, J; Adamyan, A; Danilov, A V; Lindström, T; Fogelström, M; Bauch, T; Johansson, G; Kubatkin, S E

    2013-09-27

    We study a superconducting charge qubit coupled to an intensive electromagnetic field and probe changes in the resonance frequency of the formed dressed states. At large driving strengths, exceeding the qubit energy-level splitting, this reveals the well known Landau-Zener-Stückelberg interference structure of a longitudinally driven two-level system. For even stronger drives, we observe a significant change in the Landau-Zener-Stückelberg pattern and contrast. We attribute this to photon-assisted quasiparticle tunneling in the qubit. This results in the recovery of the qubit parity, eliminating effects of quasiparticle poisoning, and leads to an enhanced interferometric response. The interference pattern becomes robust to quasiparticle poisoning and has a good potential for accurate charge sensing.

  1. Robust techniques for polarization and detection of nuclear spin ensembles

    Science.gov (United States)

    Scheuer, Jochen; Schwartz, Ilai; Müller, Samuel; Chen, Qiong; Dhand, Ish; Plenio, Martin B.; Naydenov, Boris; Jelezko, Fedor

    2017-11-01

    Highly sensitive nuclear spin detection is crucial in many scientific areas including nuclear magnetic resonance spectroscopy, magnetic resonance imaging (MRI), and quantum computing. The tiny thermal nuclear spin polarization represents a major obstacle towards this goal which may be overcome by dynamic nuclear spin polarization (DNP) methods. The latter often rely on the transfer of the thermally polarized electron spins to nearby nuclear spins, which is limited by the Boltzmann distribution of the former. Here we utilize microwave dressed states to transfer the high (>92 % ) nonequilibrium electron spin polarization of a single nitrogen-vacancy center (NV) induced by short laser pulses to the surrounding 13C carbon nuclear spins. The NV is repeatedly repolarized optically, thus providing an effectively infinite polarization reservoir. A saturation of the polarization of the nearby nuclear spins is achieved, which is confirmed by the decay of the polarization transfer signal and shows an excellent agreement with theoretical simulations. Hereby we introduce the polarization readout by polarization inversion method as a quantitative magnetization measure of the nuclear spin bath, which allows us to observe by ensemble averaging macroscopically hidden polarization dynamics like Landau-Zener-Stückelberg oscillations. Moreover, we show that using the integrated solid effect both for single- and double-quantum transitions nuclear spin polarization can be achieved even when the static magnetic field is not aligned along the NV's crystal axis. This opens a path for the application of our DNP technique to spins in and outside of nanodiamonds, enabling their application as MRI tracers. Furthermore, the methods reported here can be applied to other solid state systems where a central electron spin is coupled to a nuclear spin bath, e.g., phosphor donors in silicon and color centers in silicon carbide.

  2. Excellent nonlinearity of a selection device based on anti-series connected Zener diodes for ultrahigh-density bipolar RRAM arrays

    International Nuclear Information System (INIS)

    Li, Yingtao; Li, Rongrong; Wang, Yang; Tao, Chunlan; Fu, Liping; Gao, Xiaoping

    2015-01-01

    A crossbar array is usually used for the high-density application of a resistive random access memory (RRAM) device. However, the cross-talk interference limits the increase in the integration density. In this paper, anti-series connected Zener diodes as a selection device are proposed for bipolar RRAM arrays. Simulation results show that, by using the anti-series connected Zener diodes as a selection device, the readout margin is sufficiently improved compared to that obtained without a selection device or with anti-parallel connected diodes as the selection device. The maximum size of the crossbar arrays with anti-series connected Zener diodes as a selection device over 1 TB is estimated by theoretical simulation. In addition, the feasibility of using the anti-series connected Zener diodes as a selection device for bipolar RRAM is demonstrated experimentally. These results indicate that anti-series connected Zener diodes as a selection device opens up great opportunities to realize ultrahigh-density bipolar RRAM arrays. (paper)

  3. Zener Diode Compact Model Parameter Extraction Using Xyce-Dakota Optimization.

    Energy Technology Data Exchange (ETDEWEB)

    Buchheit, Thomas E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wilcox, Ian Zachary [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sandoval, Andrew J [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Reza, Shahed [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-12-01

    This report presents a detailed process for compact model parameter extraction for DC circuit Zener diodes. Following the traditional approach of Zener diode parameter extraction, circuit model representation is defined and then used to capture the different operational regions of a real diode's electrical behavior. The circuit model contains 9 parameters represented by resistors and characteristic diodes as circuit model elements. The process of initial parameter extraction, the identification of parameter values for the circuit model elements, is presented in a way that isolates the dependencies between certain electrical parameters and highlights both the empirical nature of the extraction and portions of the real diode physical behavior which of the parameters are intended to represent. Optimization of the parameters, a necessary part of a robost parameter extraction process, is demonstrated using a 'Xyce-Dakota' workflow, discussed in more detail in the report. Among other realizations during this systematic approach of electrical model parameter extraction, non-physical solutions are possible and can be difficult to avoid because of the interdependencies between the different parameters. The process steps described are fairly general and can be leveraged for other types of semiconductor device model extractions. Also included in the report are recommendations for experiment setups for generating optimum dataset for model extraction and the Parameter Identification and Ranking Table (PIRT) for Zener diodes.

  4. Zener solutions for particle growth in multi-component alloys

    NARCIS (Netherlands)

    Vermolen, F.J.

    2006-01-01

    In this paper the Zener theory on precipitate growth in supersaturated alloys for planar, cylindrical and spherical geometries is extended to multi-component alloys. The obtained solutions can be used to check the results from numerical simulations under simplified conditions. Further, the

  5. Nuclear magnetism of liquid 3He: new determination of the Landau parameter F0a

    International Nuclear Information System (INIS)

    Goudon, V.

    2006-10-01

    He 3 is a liquid Fermi model, isotropic, with an attainable Fermi temperature and the interaction between atoms can be controlled by changing the pressure of the liquid. In this document, we present accurate NMR measurements of the nuclear magnetic susceptibility of liquid He 3 as a function of temperature and pressure. The emphasis has been placed on reliable thermometry and on He 3 pressure measurements directly in the cell to increase the measuring range until solidification, and an accurate characterization of the NMR spectrometer. Our measurements give an effective Fermi temperature 5% lower than former results. The Landau parameter F 0 a depends on the effective mass, which is determined by specific heat measurements, and consequently on the temperature scale. The re-analysis of the specific heat measurements with the PLTS-2000 temperature scale yields an effective mass increase of 4.5%. In this document, F 0 a is determined for 2 temperature scales (PLTS-2000 and Greywall). Contrarily to former measurements, the F 0 a density dependence does not show any saturation at high pressures. (author)

  6. Adiabatically modeling quantum gates with two-site Heisenberg spins chain: Noise vs interferometry

    Science.gov (United States)

    Jipdi, M. N.; Tchoffo, M.; Fai, L. C.

    2018-02-01

    We study the Landau Zener (LZ) dynamics of a two-site Heisenberg spin chain assisted with noise and focus on the implementation of logic gates via the resulting quantum interference. We present the evidence of the quantum interference phenomenon in triplet spin states and confirm that, three-level systems mimic Landau-Zener-Stückelberg (LZS) interferometers with occupancies dependent on the effective phase. It emerges that, the critical parameters tailoring the system are obtained for constructive interferences where the two sets of the chain are found to be maximally entangled. Our findings demonstrate that the enhancement of the magnetic field strength suppresses noise effects; consequently, the noise severely impacts the occurrence of quantum interference for weak magnetic fields while for strong fields, quantum interference subsists and allows the modeling of universal sets of quantum gates.

  7. Decoherence and Landau-Damping

    Energy Technology Data Exchange (ETDEWEB)

    Ng, K.Y.; /Fermilab

    2005-12-01

    The terminologies, decoherence and Landau damping, are often used concerning the damping of a collective instability. This article revisits the difference and relation between decoherence and Landau damping. A model is given to demonstrate how Landau damping affects the rate of damping coming from decoherence.

  8. Quantum effects on curve crossing in a Bose-Einstein condensate

    International Nuclear Information System (INIS)

    Yurovsky, V.A.; Ben-Reuven, A.; Julienne, P.S.

    2002-01-01

    Formation of atomic pairs by the dissociation of a molecular condensate or by inelastic collisions in an atomic condensate due to a time-dependent curve crossing process is studied beyond the mean-field approximation. The number of atoms formed by the spontaneous process is described by a Landau-Zener formula multiplied by an exponential amplification factor due to quantum many-body effects. Correlated atomic pairs are formed in squeezed states. The rate of stimulated processes depends on the relative phase of the two fields

  9. From the atomic bomb to the Landau Institute autobiography top non-secret

    CERN Document Server

    Khalatnikov, Isaak M

    2012-01-01

    The book is an expanded autobiography of the famous theoretical physicist Isaak Khalatnikov. He worked together with L.D. Landau at the Institute for Physical Problems lead by P.L. Kapitza. He is the co-author of L.D. Landau in a number of important works. They worked together in the frame of the so-called Nuclear Bomb Project. After the death of L.D. Landau, I.M. Khalatnikov initiated the establishment of the Institute for Theoretical Physics, named in honour of L.D. Landau, within the USSR Academy of Sciences. He headed this institute from the beginning as its Director. The institute inherited almost all traditions of the Landau scientific school and played a prominent role in the development of theoretical physics. So, this is a story about how the institute was created, how it worked, and about the life of the physicists in the "golden age" of the Soviet science. A separate chapter is devoted to today´s life of the institute and the young generation of physicists working now in science. It is an historic...

  10. Isospin effects on collective nuclear dynamics

    CERN Document Server

    Di Toro, M; Baran, V; Larionov, A B

    1999-01-01

    We suggest several ways to study properties of the symmetry term in the nuclear equation of state, EOS, from collective modes in beta-unstable nuclei. After a general discussion on compressibility and saturation density in asymmetric nuclear matter we show some predictions on the collective response based on the solution of generalized Landau dispersion relations. Isoscalar-isovector coupling, disappearance of collectivity and possibility of new instabilities in low and high density regions are discussed with accent on their relation to the symmetry term of effective forces. The onset of chemical plus mechanical instabilities in a dilute asymmetric nuclear matter is discussed with reference to new features in fragmentation reactions.

  11. Tunneling magnetoresistance dependence on the temperature in a ferromagnetic Zener diode

    Energy Technology Data Exchange (ETDEWEB)

    Comesana, E; Aldegunde, M; GarcIa-Loureiro, A, E-mail: enrique.comesana@usc.e [Departamento de Electronica e Computacion, Universidade de Santiago de Compostela, 15782 Santiago de Compostela (Spain)

    2009-11-15

    In the present work we focus on the study of the temperature dependence of the tunnelling current in a ferromagnetic Zener diode. We predict the tunneling magnetoresistance dependence on the temperature. Large doping concentrations lead to magnetic semiconductors with Curie temperature T{sub C} near or over room temperature and this will facilitate the introduction of new devices that make use of the ferromagnetism effects. According to our calculations the tunneling magnetoresistance has the form TMR {proportional_to} (T{sup n}{sub C}-T{sup n}).

  12. Molecular (Feshbach) treatment of charge exchange Li3++He collisions. II. Cross sections

    International Nuclear Information System (INIS)

    Errea, L.F.; Martin, F.; Mendez, L.; Riera, A.; Yanez, M.

    1986-01-01

    Using the wave functions calculated in the preceding article, and a common translation factor, the charge exchange cross section for the Li 3+ +He(1s 2 ) reaction is calculated, and the mechanism of the process discussed. We show how small deviations from the Landau--Zener model, which are unrelated to Nikitin's conditions for its validity, lead to a minimum of the cross section at an impact energy Eapprox. =1 keV, and to larger values of sigma at intermediate nuclear velocities

  13. Effect of Landau damping on kinetic Alfven and ion-acoustic solitary waves in a magnetized nonthermal plasma with warm ions

    International Nuclear Information System (INIS)

    Bandyopadhyay, Anup; Das, K.P.

    2002-01-01

    The evolution equations describing both kinetic Alfven wave and ion-acoustic wave in a nonthermal magnetized plasma with warm ions including weak nonlinearity and weak dispersion with the effect of Landau damping have been derived. These equations reduce to two coupled equations constituting the KdV-ZK (Korteweg-de Vries-Zakharov-Kuznetsov) equation for both kinetic Alfven wave and ion-acoustic wave, including an extra term accounting for the effect of Landau damping. When the coefficient of the nonlinear term of the evolution equation for ion-acoustic wave vanishes, the nonlinear behavior of ion-acoustic wave, including the effect of Landau damping, is described by two coupled equations constituting the modified KdV-ZK (MKdV-ZK) equation, including an extra term accounting for the effect of Landau damping. It is found that there is no effect of Landau damping on the solitary structures of the kinetic Alfven wave. Both the macroscopic evolution equations for the ion-acoustic wave admits solitary wave solutions, the former having a sech 2 profile and the latter having a sech profile. In either case, it is found that the amplitude of the ion-acoustic solitary wave decreases slowly with time

  14. Exploring the mechanical behavior of degrading swine neural tissue at low strain rates via the fractional Zener constitutive model.

    Science.gov (United States)

    Bentil, Sarah A; Dupaix, Rebecca B

    2014-02-01

    The ability of the fractional Zener constitutive model to predict the behavior of postmortem swine brain tissue was examined in this work. Understanding tissue behavior attributed to degradation is invaluable in many fields such as the forensic sciences or cases where only cadaveric tissue is available. To understand how material properties change with postmortem age, the fractional Zener model was considered as it includes parameters to describe brain stiffness and also the parameter α, which quantifies the viscoelasticity of a material. The relationship between the viscoelasticity described by α and tissue degradation was examined by fitting the model to data collected in a previous study (Bentil, 2013). This previous study subjected swine neural tissue to in vitro unconfined compression tests using four postmortem age groups (week). All samples were compressed to a strain level of 10% using two compressive rates: 1mm/min and 5mm/min. Statistical analysis was used as a tool to study the influence of the fractional Zener constants on factors such as tissue degradation and compressive rate. Application of the fractional Zener constitutive model to the experimental data showed that swine neural tissue becomes less stiff with increased postmortem age. The fractional Zener model was also able to capture the nonlinear viscoelastic features of the brain tissue at low strain rates. The results showed that the parameter α was better correlated with compressive rate than with postmortem age. © 2013 Published by Elsevier Ltd.

  15. Modulated Langmuir waves and nonlinear Landau damping

    International Nuclear Information System (INIS)

    Yajima, Nobuo; Oikawa, Masayuki; Satsuma, Junkichi; Namba, Chusei.

    1975-01-01

    The nonlinear Schroedinger euqation with an integral term, iusub(t)+P/2.usub(xx)+Q/u/ 2 u+RP∫sub(-infinity)sup(infinity)[/u(x',t)/ 2 /(x-x')]dx'u=0, which describes modulated Langmuir waves with the nonlinear Landau damping effect, is solved by numerical calculations. Especially, the effects of nonlinear Landau damping on solitary wave solutions are studied. For both cases, PQ>0 and PQ<0, the results show that the solitary waves deform in an asymmetric way changing its velocity. (auth.)

  16. Molecular (Feshbach) treatment of charge exchange Li/sup 3 +/+He collisions. II. Cross sections

    Energy Technology Data Exchange (ETDEWEB)

    Errea, L.F.; Martin, F.; Mendez, L.; Riera, A.; Yanez, M.

    1986-05-15

    Using the wave functions calculated in the preceding article, and a common translation factor, the charge exchange cross section for the Li/sup 3 +/+He(1s/sup 2/) reaction is calculated, and the mechanism of the process discussed. We show how small deviations from the Landau--Zener model, which are unrelated to Nikitin's conditions for its validity, lead to a minimum of the cross section at an impact energy Eapprox. =1 keV, and to larger values of sigma at intermediate nuclear velocities.

  17. Viscosity effect in Landau's hydrodynamical model

    International Nuclear Information System (INIS)

    Hoang, T.F.; Phua, K.K.; Nanyang Univ., Singapore

    1979-01-01

    The Bose-Einstein distribution is used to investigate Landau's hydrodynamical model with viscosity. In case the viscosity dependence on the temperature is T 3 , the correction to the multiplicity behaves like I/E and is found to be negligible for the pp data. A discussion is presented on a possibility of reconciling E 1 / 2 and logE dependence of the multiplicity law. (orig.)

  18. Chiral correlators in Landau-Ginsburg theories and N=2 superconformal models

    International Nuclear Information System (INIS)

    Howe, P.S.; West, P.C.

    1989-01-01

    Chiral correlation functions are computed in N=2 Landau-Ginsburg models using the ε-expansion and the superconformal Ward identities for the Landau-Ginsburg effective action. They are also computed directly using superconformal model techniques. The same results are obtained yielding further confirmation of the identification of superconformal minimal models with Landau-Ginsburg models evaluated at their fixed points. The formulae for the chiral commutators that we compute are extremely simple when expressed in terms of effective actions. (orig.)

  19. Shell effects in the superasymmetric fission

    CERN Document Server

    Mirea, M

    2002-01-01

    A new formalism based on the Landau-Zener promotion mechanism intends to explain the fine structure of alpha and cluster decay. The analysis of this phenomenon is accomplished by following the modality in which the shells are reorganized during the decay process beginning with the initial ground state of the parent towards the final configuration of two separated nuclei. A realistic level scheme is obtained in the framework of the superasymmetric two-center shell model. (author)

  20. Quantum driving of a two level system: quantum speed limit and superadiabatic protocols – an experimental investigation

    International Nuclear Information System (INIS)

    Malossi, N; Arimondo, E; Ciampini, D; Mannella, R; Bason, M G; Viteau, M; Morsch, O

    2013-01-01

    A fundamental requirement in quantum information processing and in many other areas of science is the capability of precisely controlling a quantum system by preparing a quantum state with the highest fidelity and/or in the fastest possible way. Here we present an experimental investigation of a two level system, characterized by a time-dependent Landau-Zener Hamiltonian, aiming to test general and optimal high-fidelity control protocols. The experiment is based on a Bose-Einstein condensate (BEC) loaded into an optical lattice, then accelerated, which provides a high degree of control over the experimental parameters. We implement generalized Landau-Zener sweeps, comparing them with the well-known linear Landau-Zener sweep. We drive the system from an initial state to a final state with fidelity close to unity in the shortest possible time (quantum brachistochrone), thus reaching the ultimate speed limit imposed by quantum mechanics. On the opposite extreme of the quantum control spectrum, the aim is not to minimize the total transition time but to maximize the adiabaticity during the time-evolution, the system being constrained to the adiabatic ground state at any time. We implement such transitionless superadiabatic protocols by an appropriate transformation of the Hamiltonian parameters. This transformation is general and independent of the physical system.

  1. Ginzburg-Landau vortices driven by the Landau-Lifshitz-Gilbert equation

    Energy Technology Data Exchange (ETDEWEB)

    Kurzke, Matthias; Melcher, Christof; Moser, Roger; Spirn, Daniel

    2009-06-15

    A simplified model for the energy of the magnetization of a thin ferromagnetic film gives rise to a version of the theory of Ginzburg-Landau vortices for sphere-valued maps. In particular we have the development of vortices as a certain parameter tends to 0. The dynamics of the magnetization is ruled by the Landau-Lifshitz-Gilbert equation, which combines characteristic properties of a nonlinear Schroedinger equation and a gradient flow. This paper studies the motion of the vortex centers under this evolution equation. (orig.)

  2. Ginzburg-Landau vortices driven by the Landau-Lifshitz-Gilbert equation

    International Nuclear Information System (INIS)

    Kurzke, Matthias; Melcher, Christof; Moser, Roger; Spirn, Daniel

    2009-01-01

    A simplified model for the energy of the magnetization of a thin ferromagnetic film gives rise to a version of the theory of Ginzburg-Landau vortices for sphere-valued maps. In particular we have the development of vortices as a certain parameter tends to 0. The dynamics of the magnetization is ruled by the Landau-Lifshitz-Gilbert equation, which combines characteristic properties of a nonlinear Schroedinger equation and a gradient flow. This paper studies the motion of the vortex centers under this evolution equation. (orig.)

  3. Ginzburg-Landau-type theory of nonpolarized spin superconductivity

    Science.gov (United States)

    Lv, Peng; Bao, Zhi-qiang; Guo, Ai-Min; Xie, X. C.; Sun, Qing-Feng

    2017-01-01

    Since the concept of spin superconductor was proposed, all the related studies concentrate on the spin-polarized case. Here, we generalize the study to the spin-non-polarized case. The free energy of nonpolarized spin superconductor is obtained, and Ginzburg-Landau-type equations are derived by using the variational method. These Ginzburg-Landau-type equations can be reduced to the spin-polarized case when the spin direction is fixed. Moreover, the expressions of super linear and angular spin currents inside the superconductor are derived. We demonstrate that the electric field induced by the super spin current is equal to the one induced by an equivalent charge obtained from the second Ginzburg-Landau-type equation, which shows self-consistency of our theory. By applying these Ginzburg-Landau-type equations, the effect of electric field on the superconductor is also studied. These results will help us get a better understanding of the spin superconductor and related topics such as the Bose-Einstein condensate of magnons and spin superfluidity.

  4. Landau damping due to tune spreads in betatron amplitude and momentum

    International Nuclear Information System (INIS)

    Lee, S.Y.; Tran, P.; Weng, W.T.

    1989-01-01

    Due to the large space charge transverse impedance in a low energy synchrotron, the coherent tune shift causes the Landau damping to be ineffective in damping the transverse coherent motion. We analyze the effect of Landau damping that is caused by the tune spreads of the betatron amplitude (space charge and/or octupole) and momentum. We find that the Landau damping becomes more significant in our two dimensional analysis. 5 refs

  5. Landau retardation on the occurrence scattering time in quantum electron–hole plasmas

    International Nuclear Information System (INIS)

    Hong, Woo-Pyo; Jung, Young-Dae

    2016-01-01

    The Landau damping effects on the occurrence scattering time in electron collisions are investigated in a quantum plasma composed of electrons and holes. The Shukla–Stenflo–Bingham effective potential model is employed to obtain the occurrence scattering time in a quantum electron–hole plasma. The result shows that the influence of Landau damping produces the imaginary term in the scattering amplitude. It is then found that the Landau damping generates the retardation effect on the occurrence scattering time. It is found that the occurrence scattering time increases in forward scattering domains and decreases in backward scattering domains with an increase of the Landau parameter. It is also found that the occurrence scattering time decreases with increasing collision energy. In addition, it is found that the quantum shielding effect enhances the occurrence scattering time in the forward scattering and, however, suppresses the occurrence scattering time in the backward scattering. - Highlights: • The Landau damping effects on the occurrence scattering time are investigated in a quantum electron–hole plasma. • The Shukla–Stenflo–Bingham potential model is employed to obtain the occurrence scattering time in quantum plasmas. • The influence of quantum shielding on the occurrence scattering time is discussed.

  6. Landau damping of dust acoustic solitary waves in nonthermal plasmas

    Science.gov (United States)

    Ghai, Yashika; Saini, N. S.; Eliasson, B.

    2018-01-01

    Dust acoustic (DA) solitary and shock structures have been investigated under the influence of Landau damping in a dusty plasma containing two temperature nonthermal ions. Motivated by the observations of Geotail spacecraft that reported two-temperature ion population in the Earth's magnetosphere, we have investigated the effect of resonant wave-particle interactions on DA nonlinear structures. The Korteweg-de Vries (KdV) equation with an additional Landau damping term is derived and its analytical solution is presented. The solution has the form of a soliton whose amplitude decreases with time. Further, we have illustrated the influence of Landau damping and nonthermality of the ions on DA shock structures by a numerical solution of the Landau damping modified KdV equation. The study of the time evolution of shock waves suggests that an initial shock-like pulse forms an oscillatory shock at later times due to the balance of nonlinearity, dispersion, and dissipation due to Landau damping. The findings of the present investigation may be useful in understanding the properties of nonlinear structures in the presence of Landau damping in dusty plasmas containing two temperature ions obeying nonthermal distribution such as in the Earth's magnetotail.

  7. Landau Damping Revisited

    International Nuclear Information System (INIS)

    Rees, John; Chao, Alexander

    2008-01-01

    Landau damping, as the term is used in accelerator science, is a physical process in which an ensemble of harmonic oscillators--an accelerator beam, for example--that would otherwise be unstable is stabilized by a spread in the natural frequencies of the oscillators. This is a study of the most basic aspects of that process. It has two main goals: to gain a deeper insight into the mechanism of Landau damping and to find the coherent motion of the ensemble and thus the dependence of the total damping rate on the frequency spread

  8. Energy spread in SLC linac with Landau damping

    International Nuclear Information System (INIS)

    Seeman, J.

    1984-01-01

    The possibility of using Landau damping to reduce the growth of the beam size due to transverse wake fields has been known for some time. Recently K. Bane has calculated the effects of Landau damping for the SLC. The energy spread is then slowly removed so that at the end of the linac it has returned to the SLC specification of less than +0.5%. The purpose of the energy spread is to reduce the resonant driving of the tail of the bunch by the head. In this note the expected energy spreads within the beam are tabulated at various positions along the linac for use by those people designing momentum dependent equipment and for those interested in Landau damping

  9. The lowest Landau level in QCD

    Directory of Open Access Journals (Sweden)

    Bruckmann Falk

    2017-01-01

    Full Text Available The thermodynamics of Quantum Chromodynamics (QCD in external (electro-magnetic fields shows some unexpected features like inverse magnetic catalysis, which have been revealed mainly through lattice studies. Many effective descriptions, on the other hand, use Landau levels or approximate the system by just the lowest Landau level (LLL. Analyzing lattice configurations we ask whether such a picture is justified. We find the LLL to be separated from the rest by a spectral gap in the two-dimensional Dirac operator and analyze the corresponding LLL signature in four dimensions. We determine to what extent the quark condensate is LLL dominated at strong magnetic fields.

  10. Discretisation errors in Landau gauge on the lattice

    International Nuclear Information System (INIS)

    Bonnet DR, Frederic; Bowman O, Patrick; Leinweber B, Derek; Williams G, Anthony; Richards G, David G.

    1999-01-01

    Lattice discretization errors in the Landau gauge condition are examined. An improved gauge fixing algorithm in which O(a 2 ) errors are removed is presented. O(a 2 ) improvement of the gauge fixing condition improves comparison with continuum Landau gauge in two ways: (1) through the elimination of O(a 2 ) errors and (2) through a secondary effect of reducing the size of higher-order errors. These results emphasize the importance of implementing an improved gauge fixing condition

  11. Discretisation errors in Landau gauge on the lattice

    International Nuclear Information System (INIS)

    Bonnet, F.D.R.; Bowmen, P.O.; Leinweber, D.B.

    1999-01-01

    Lattice discretisation errors in the Landau gauge condition are examined. An improved gauge fixing algorithm in which O(a 2 ) errors are removed is presented. O(a 2 ) improvement of the gauge fixing condition improves comparison with the continuum Landau gauge in two ways: (1) through the elimination of O(a 2 ) errors and (2) through a secondary effect of reducing the size of higher-order errors. These results emphasise the importance of implementing an improved gauge fixing condition. Copyright (1999) CSIRO Australia

  12. The Landau theory of phase transitions

    Indian Academy of Sciences (India)

    2 Department of Computer Sci- ence, Indian ... in plasma physics, the Landau pole in quantum electro-. Keywords ... with Vitalyn Ginzburg, Landau made a milestone con- tribution to ..... This work was supported by the Physics Olympiad Pro-.

  13. Sum rules for nuclear excitations with the Skyrme-Landau interaction

    International Nuclear Information System (INIS)

    Liu Kehfei; Luo Hongde; Ma Zhongyu; Feng Man; Shen Qingbiao

    1991-01-01

    The energy-weighted sum rules for electric, magnetic, Fermi and Gamow-Teller transitions with the Skyrme-Landau interaction are derived from the double commutators and numerically calculated in a HF + RPA formalism. As a numerical check of the Thouless theorem, our self-consistent calculations show that the calculated RPA strengths exhaust more than 85% of the sum rules in most cases. The well known non-energy-weighted sum rules for Fermi and Gamow-Teller transitions are also checked numerically. The sum rules are exhausted by more than 94% in these cases. (orig.)

  14. Tuning of graphene nanoribbon Landau levels by a nanotube

    International Nuclear Information System (INIS)

    Li, T S; Chang, S C; Lin, M F

    2009-01-01

    We investigate theoretically the effects of a nanotube on the graphene nanoribbon Landau level spectrum utilizing the tight-binding model. The addition of a nanotube changes the original dispersionless Landau subbands into distorted parabolic ones, creates additional band-edge states, and modifies the subband spacings. Moreover, the dispersion relations rely sensitively on the nanotube location. The nanotube-ribbon couplings disrupt the Landau wavefunctions and lift their spatial symmetry, which will change the selection rule of optical transitions. The numbers, frequencies and heights of the density of states (DOS) peaks are found to be strongly dependent on the magnetic flux density and the nanotube location. The evolution of the DOS peak with the magnetic flux density is explored. The graphene nanoribbon Landau levels are shown to be modified in an unexpected fashion by the nanotube-ribbon interactions. These predictions can be validated by measuring the spectra of scanning tunneling experiments or magneto-optical experiments, and they are most observable by placing the nanotube at the electron wavefunction localization sites.

  15. Simplified Model of Nonlinear Landau Damping

    International Nuclear Information System (INIS)

    Yampolsky, N.A.; Fisch, N.J.

    2009-01-01

    The nonlinear interaction of a plasma wave with resonant electrons results in a plateau in the electron distribution function close to the phase velocity of the plasma wave. As a result, Landau damping of the plasma wave vanishes and the resonant frequency of the plasma wave downshifts. However, this simple picture is invalid when the external driving force changes the plasma wave fast enough so that the plateau cannot be fully developed. A new model to describe amplification of the plasma wave including the saturation of Landau damping and the nonlinear frequency shift is proposed. The proposed model takes into account the change of the plasma wave amplitude and describes saturation of the Landau damping rate in terms of a single fluid equation, which simplifies the description of the inherently kinetic nature of Landau damping. A proposed fluid model, incorporating these simplifications, is verified numerically using a kinetic Vlasov code.

  16. On the quantum Landau collision operator and electron collisions in dense plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Daligault, Jérôme, E-mail: daligaul@lanl.gov [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2016-03-15

    The quantum Landau collision operator, which extends the widely used Landau/Fokker-Planck collision operator to include quantum statistical effects, is discussed. The quantum extension can serve as a reference model for including electron collisions in non-equilibrium dense plasmas, in which the quantum nature of electrons cannot be neglected. In this paper, the properties of the Landau collision operator that have been useful in traditional plasma kinetic theory and plasma transport theory are extended to the quantum case. We outline basic properties in connection with the conservation laws, the H-theorem, and the global and local equilibrium distributions. We discuss the Fokker-Planck form of the operator in terms of three potentials that extend the usual two Rosenbluth potentials. We establish practical closed-form expressions for these potentials under local thermal equilibrium conditions in terms of Fermi-Dirac and Bose-Einstein integrals. We study the properties of linearized quantum Landau operator, and extend two popular approximations used in plasma physics to include collisions in kinetic simulations. We apply the quantum Landau operator to the classic test-particle problem to illustrate the physical effects embodied in the quantum extension. We present useful closed-form expressions for the electron-ion momentum and energy transfer rates. Throughout the paper, similarities and differences between the quantum and classical Landau collision operators are emphasized.

  17. On the quantum Landau collision operator and electron collisions in dense plasmas

    Science.gov (United States)

    Daligault, Jérôme

    2016-03-01

    The quantum Landau collision operator, which extends the widely used Landau/Fokker-Planck collision operator to include quantum statistical effects, is discussed. The quantum extension can serve as a reference model for including electron collisions in non-equilibrium dense plasmas, in which the quantum nature of electrons cannot be neglected. In this paper, the properties of the Landau collision operator that have been useful in traditional plasma kinetic theory and plasma transport theory are extended to the quantum case. We outline basic properties in connection with the conservation laws, the H-theorem, and the global and local equilibrium distributions. We discuss the Fokker-Planck form of the operator in terms of three potentials that extend the usual two Rosenbluth potentials. We establish practical closed-form expressions for these potentials under local thermal equilibrium conditions in terms of Fermi-Dirac and Bose-Einstein integrals. We study the properties of linearized quantum Landau operator, and extend two popular approximations used in plasma physics to include collisions in kinetic simulations. We apply the quantum Landau operator to the classic test-particle problem to illustrate the physical effects embodied in the quantum extension. We present useful closed-form expressions for the electron-ion momentum and energy transfer rates. Throughout the paper, similarities and differences between the quantum and classical Landau collision operators are emphasized.

  18. Landau-Ginzburg skeletons

    Energy Technology Data Exchange (ETDEWEB)

    Davenport, Ian C.; Melnikov, Ilarion V. [Department of Physics and Astronomy, James Madison University,Harrisonburg, VA 22807 (United States)

    2017-05-10

    We study the class of indecomposable two-dimensional Landau-Ginzburg theories with (2,2) supersymmetry and central charge c < 6 with the aim of classifying all such theories up to marginal deformations. Our results include cases overlooked in previous classifications. The results are rigorous for three or fewer fields and more generally are rigorous if we assume an extra bound. Numerics suggest that we have the complete set of indecomposable Landau-Ginzburg families with c < 6. This set consists of 38 infinite families and a finite list of 418 sporadic cases. The basic tools are classic results of Kreuzer and Skarke on quasi-homogeneous isolated singularities and solutions to certain feasibility integer programming problems.

  19. Landau quantization of Dirac fermions in graphene and its multilayers

    Science.gov (United States)

    Yin, Long-Jing; Bai, Ke-Ke; Wang, Wen-Xiao; Li, Si-Yu; Zhang, Yu; He, Lin

    2017-08-01

    When electrons are confined in a two-dimensional (2D) system, typical quantum-mechanical phenomena such as Landau quantization can be detected. Graphene systems, including the single atomic layer and few-layer stacked crystals, are ideal 2D materials for studying a variety of quantum-mechanical problems. In this article, we review the experimental progress in the unusual Landau quantized behaviors of Dirac fermions in monolayer and multilayer graphene by using scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). Through STS measurement of the strong magnetic fields, distinct Landau-level spectra and rich level-splitting phenomena are observed in different graphene layers. These unique properties provide an effective method for identifying the number of layers, as well as the stacking orders, and investigating the fundamentally physical phenomena of graphene. Moreover, in the presence of a strain and charged defects, the Landau quantization of graphene can be significantly modified, leading to unusual spectroscopic and electronic properties.

  20. Revisiting the Landau fluid closure.

    Science.gov (United States)

    Hunana, P.; Zank, G. P.; Webb, G. M.; Adhikari, L.

    2017-12-01

    Advanced fluid models that are much closer to the full kinetic description than the usual magnetohydrodynamic description are a very useful tool for studying astrophysical plasmas and for interpreting solar wind observational data. The development of advanced fluid models that contain certain kinetic effects is complicated and has attracted much attention over the past years. Here we focus on fluid models that incorporate the simplest possible forms of Landau damping, derived from linear kinetic theory expanded about a leading-order (gyrotropic) bi-Maxwellian distribution function f_0, under the approximation that the perturbed distribution function f_1 is gyrotropic as well. Specifically, we focus on various Pade approximants to the usual plasma response function (and to the plasma dispersion function) and examine possibilities that lead to a closure of the linear kinetic hierarchy of fluid moments. We present re-examination of the simplest Landau fluid closures.

  1. Landau damping dynamic aperture and octupole in LHC

    CERN Document Server

    Gareyte, Jacques; Ruggiero, F

    1997-01-01

    Maximization of the dynamic aperture and Landau damping of the collective instabilities are partly conflicting requirements. On the one hand, the non-linearities of the lattice must be minimized at large oscillation amplitude to guarantee the stability of the single particle motion. On the other hand, a spread of the betatron frequencies is necessary to guarantee the stability of the collective motion of bunches of particles; this requires the introduction of non-linearities effective at small amplitudes. We show in this note that the `natural' spread of betatron tunes due to the field imperfections is inadequate or Landau damping. An octupole scheme is required to provide collective stability at high energy. At low energy it may be used to find the optimum between the correction of the octupolar field imperfections and Landau damping. The solution of the stability problem taking into account the two degrees of freedom of the transverse motion allows a significant saving in octupole strength: 144 octupoles wi...

  2. Landau-Kleffner syndrome: study of four cases Síndrome de Landau-Kleffner: estudo de quatro casos

    Directory of Open Access Journals (Sweden)

    Lúcia H. Coutinho dos Santos

    2002-06-01

    Full Text Available We describe four patients with clinical features of Landau-Kleffner syndrome and discuss electroencephalographic features, treatment and prognosis. Anticonvulsants and prednisone were used for treatment with good control of seizures in all cases and a less effect response in acquired aphasia. Further studies are necessary to elucidate the causes and management of this syndrome.Descrevemos quatro pacientes com achados clínicos de síndrome de Landau Kleffner . São discutidos os aspectos relacionados aos achados eletrencefalográficos, tratamento e prognóstico. Anticonvulsivantes e prednisona foram os principais métodos terapêuticos utilizados com controle das crises convulsivas em todos os casos e resposta variável quanto a afasia adquirida. Mais estudos são necessários para elucidar as causas e o manejo desta síndrome

  3. Dynamical Monte Carlo investigation of spin reversals and nonequilibrium magnetization of single-molecule magnets

    OpenAIRE

    Liu, Gui-Bin; Liu, Bang-Gui

    2010-01-01

    In this paper, we combine thermal effects with Landau-Zener (LZ) quantum tunneling effects in a dynamical Monte Carlo (DMC) framework to produce satisfactory magnetization curves of single-molecule magnet (SMM) systems. We use the giant spin approximation for SMM spins and consider regular lattices of SMMs with magnetic dipolar interactions (MDI). We calculate spin reversal probabilities from thermal-activated barrier hurdling, direct LZ tunneling, and thermal-assisted LZ tunnelings in the pr...

  4. Studies of electron correlation effects in multicharged ion atom collisions involving double capture

    International Nuclear Information System (INIS)

    Stolterfoht, N.; Sommer, K.; Griffin, D.C.; Havener, C.C.; Huq, M.S.; Phaneuf, R.A.; Swenson, J.K.; Meyer, F.W.

    1988-01-01

    We review measurements of L-Coster Kronig and Auger electron production in slow, multicharged collision systems to study electron correlation effects in the process of double electron capture. The n/sup /minus/3/ law was confirmed for the production of the Coster-Kronig configurations 1s 2 2pn/ell/ (n ≥ 6) in O 6+ + He collisions. Enhancement of high angular momentum /ell/ in specific 1s 2 2pn/ell/ configurations was observed by means of high-resolution measurements of the Coster-Kronig lines. The importance of electron correlation effects in couplings of potential energy curves leading to the 1s 2 2pn/ell/ configurations is verified by means of Landau-Zener model calculations. 32 refs., 4 figs

  5. Competing Quantum Hall Phases in the Second Landau Level in Low Density Limit

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Wei [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Serafin, A. [Univ. of Florida, Gainesville, FL (United States). National High Magnetic Field Lab. (MagLab); Xia, J. S. [Univ. of Florida, Gainesville, FL (United States). National High Magnetic Field Lab. (MagLab); Liang, Y. [Univ. of Florida, Gainesville, FL (United States). National High Magnetic Field Lab. (MagLab); Sullivan, N. S. [Univ. of Florida, Gainesville, FL (United States). National High Magnetic Field Lab. (MagLab); Baldwin, K. W. [Princeton Univ., NJ (United States); West, K. W. [Princeton Univ., NJ (United States); Pfeiffer, L. N. [Princeton Univ., NJ (United States); Tsui, D. C. [Princeton Univ., NJ (United States)

    2015-01-01

    Up to date, studies of the fractional quantum Hall effect (FQHE) states in the second Landau level have mainly been carried out in the high electron density regime, where the electron mobility is the highest. Only recently, with the advance of high quality low density MBE growth, experiments have been pushed to the low density regime [1], where the electron-electron interactions are strong and the Landau level mixing parameter, defined by κ = e2/εIB/ℏωe, is large. Here, lB = (ℏe/B)1/2 is the magnetic length and ωc = eB/m the cyclotron frequency. All other parameters have their normal meanings. It has been shown that a large Landau level mixing effect strongly affects the electron physics in the second Landau level [2].

  6. Electrically pumped graphene-based Landau-level laser

    Science.gov (United States)

    Brem, Samuel; Wendler, Florian; Winnerl, Stephan; Malic, Ermin

    2018-03-01

    Graphene exhibits a nonequidistant Landau quantization with tunable Landau-level (LL) transitions in the technologically desired terahertz spectral range. Here, we present a strategy for an electrically driven terahertz laser based on Landau-quantized graphene as the gain medium. Performing microscopic modeling of the coupled electron, phonon, and photon dynamics in such a laser, we reveal that an inter-LL population inversion can be achieved resulting in the emission of coherent terahertz radiation. The presented paper provides a concrete recipe for the experimental realization of tunable graphene-based terahertz laser systems.

  7. Tuning the effects of Landau level mixing on anisotropic transport in quantum Hall systems

    International Nuclear Information System (INIS)

    Smith, Peter M; Kennett, Malcolm P

    2012-01-01

    Electron-electron interactions in half-filled high Landau levels in two-dimensional electron gases in a strong perpendicular magnetic field can lead to states with anisotropic longitudinal resistance. This longitudinal resistance is generally believed to arise from broken rotational invariance, which is indicated by charge density wave order in Hartree-Fock calculations. We use the Hartree-Fock approximation to study the influence of externally tuned Landau level mixing on the formation of interaction-induced states that break rotational invariance in two-dimensional electron and hole systems. We focus on the situation when there are two non-interacting states in the vicinity of the Fermi level and construct a Landau theory to study coupled charge density wave order that can occur as interactions are tuned and the filling or mixing are varied. We consider numerically a specific example where mixing is tuned externally through Rashba spin-orbit coupling. We calculate the phase diagram and find the possibility of ordering involving coupled striped or triangular charge density waves in the two levels. Our results may be relevant to recent transport experiments on quantum Hall nematics in which Landau level mixing plays an important role. (paper)

  8. Landau fluid model for weakly nonlinear dispersive magnetohydrodynamics

    International Nuclear Information System (INIS)

    Passot, T.; Sulem, P. L.

    2005-01-01

    In may astrophysical plasmas such as the solar wind, the terrestrial magnetosphere, or in the interstellar medium at small enough scales, collisions are negligible. When interested in the large-scale dynamics, a hydrodynamic approach is advantageous not only because its numerical simulations is easier than of the full Vlasov-Maxwell equations, but also because it provides a deep understanding of cross-scale nonlinear couplings. It is thus of great interest to construct fluid models that extended the classical magnetohydrodynamic (MHD) equations to collisionless situations. Two ingredients need to be included in such a model to capture the main kinetic effects: finite Larmor radius (FLR) corrections and Landau damping, the only fluid-particle resonance that can affect large scales and can be modeled in a relatively simple way. The Modelization of Landau damping in a fluid formalism is hardly possible in the framework of a systematic asymptotic expansion and was addressed mainly by means of parameter fitting in a linearized setting. We introduced a similar Landau fluid model but, that has the advantage of taking dispersive effects into account. This model properly describes dispersive MHD waves in quasi-parallel propagation. Since, by construction, the system correctly reproduces their linear dynamics, appropriate tests should address the nonlinear regime. In a first case, we show analytically that the weakly nonlinear modulational dynamics of quasi-parallel propagating Alfven waves is well captured. As a second test we consider the parametric decay instability of parallel Alfven waves and show that numerical simulations of the dispersive Landau fluid model lead to results that closely match the outcome of hybrid simulations. (Author)

  9. Lev Landau and the concept of neutron stars

    International Nuclear Information System (INIS)

    Yakovlev, Dmitrii G; Haensel, Pawel; Baym, Gordon; Pethick, Christopher

    2013-01-01

    We review Lev Landau's role in the history of neutron star physics in the 1930s. According to the recollections of Rosenfeld (Proc. 16th Solvay Conference on Physics, 1974, p. 174), Landau improvised the concept of neutron stars in a discussion with Bohr and Rosenfeld just after the news of the discovery of the neutron reached Copenhagen in February 1932. We present arguments that the discussion must have taken place in March 1931, before the discovery of the neutron, and that they, in fact, discussed the paper written by Landau in Zurich in February 1931 but not published until February 1932 (Phys. Z. Sowjetunion 1, 285). In this paper, Landau mentioned the possible existence of dense stars that look like one giant nucleus; this could be regarded as an early theoretical prediction or anticipation of neutron stars, albeit prior to the discovery of the neutron. The coincidence of the dates of the neutron discovery and the publication of the paper has led to an erroneous association of Landau's paper with the discovery of the neutron. In passing, we outline Landau's contribution to the theory of white dwarfs and to the hypothesis of stars with neutron cores. (from the history of physics)

  10. β-Ga2O3 solar-blind deep-ultraviolet photodetector based on a four-terminal structure with or without Zener diodes

    Directory of Open Access Journals (Sweden)

    L. X. Qian

    2016-04-01

    Full Text Available A four-terminal photodetector was fabricated on the ( 2 ¯ 01 -dominant β-Ga2O3 thin film which was deposited in a plasma-assisted molecular beam epitaxy system. The suitability of this film for solar-blind DUV detection was proved by its transmission spectra. Moreover, the device operating in a specific voltage-current mode can accurately detect the DUV radiation both qualitatively and quantitatively. Accordingly, a dark/photo voltage ratio of 15 was achieved, which is comparable to that of previously-reported β-Ga2O3 interdigital metal-semiconductor-metal photoconductor. More importantly, the aperture ratio of our proposed device exceeds 80%, nearly doubling that of the conventional interdigital metal-semiconductor-metal devices including photoconductor and Schottky-type photodiode, which can intensively benefit the detection efficiency. Furthermore, it was found the dark/photo voltage ratio was nearly trebled with the assistance of two Zener diodes, and further enhancement can be expected by increasing the operating current and/or adopting Zener diodes with smaller Zener voltage. Therefore, this work provides a promising alternative for solar-blind DUV detection.

  11. Research in theoretical nuclear physics

    International Nuclear Information System (INIS)

    Liu, Keh-Fei.

    1989-01-01

    This paper discusses: the role of nuclear binding in EMC effect; skyrmion quantization and phenomenology; lattice gauge Monte Carlo calculations; identification of tensor glueball; evidence of mesoniums in bar pm annihilation and γγ reactions; Skyrme-Landau parameterization of effective NN interactions; and quark-gluon plamsa

  12. An in situ study of the enhancement of atomic mobility under neutron irradiation in a Ag-30at%Zn alloy, using the Zener relaxation

    International Nuclear Information System (INIS)

    Halbwachs, M.; Hillairet, J.; Gonzalez, H.; Cost, J.

    1975-01-01

    An application of the Zener relaxation to the study of fast neutron effects on a Ag-Zn alloy is presented. The temperature dependence of the relaxation time is shown. It can be seen that the measured relaxation time at a given temperature increases with the irradiation doses [fr

  13. Parametric Landau damping of space charge modes

    Energy Technology Data Exchange (ETDEWEB)

    Macridin, Alexandru [Fermilab; Burov, Alexey [Fermilab; Stern, Eric [Fermilab; Amundson, James [Fermilab; Spentzouris, Panagiotis [Fermilab

    2016-09-23

    Landau damping is the mechanism of plasma and beam stabilization; it arises through energy transfer from collective modes to the incoherent motion of resonant particles. Normally this resonance requires the resonant particle's frequency to match the collective mode frequency. We have identified an important new damping mechanism, parametric Landau damping, which is driven by the modulation of the mode-particle interaction. This opens new possibilities for stability control through manipulation of both particle and mode-particle coupling spectra. We demonstrate the existence of parametric Landau damping in a simulation of transverse coherent modes of bunched accelerator beams with space charge.

  14. Microscopic Derivation of the Ginzburg-Landau Model

    DEFF Research Database (Denmark)

    Frank, Rupert; Hainzl, Christian; Seiringer, Robert

    2014-01-01

    We present a summary of our recent rigorous derivation of the celebrated Ginzburg-Landau (GL) theory, starting from the microscopic Bardeen-Cooper-Schrieffer (BCS) model. Close to the critical temperature, GL arises as an effective theory on the macroscopic scale. The relevant scaling limit...

  15. Nuclear magnetism of liquid {sup 3}He: new determination of the Landau parameter F{sub 0}{sup a}; Magnetisme nucleaire de l'{sup 3}He liquide: nouvelle determination du parametre de Landau F{sup a}{sub 0}

    Energy Technology Data Exchange (ETDEWEB)

    Goudon, V

    2006-10-15

    He{sup 3} is a liquid Fermi model, isotropic, with an attainable Fermi temperature and the interaction between atoms can be controlled by changing the pressure of the liquid. In this document, we present accurate NMR measurements of the nuclear magnetic susceptibility of liquid He{sup 3} as a function of temperature and pressure. The emphasis has been placed on reliable thermometry and on He{sup 3} pressure measurements directly in the cell to increase the measuring range until solidification, and an accurate characterization of the NMR spectrometer. Our measurements give an effective Fermi temperature 5% lower than former results. The Landau parameter F{sub 0}{sup a} depends on the effective mass, which is determined by specific heat measurements, and consequently on the temperature scale. The re-analysis of the specific heat measurements with the PLTS-2000 temperature scale yields an effective mass increase of 4.5%. In this document, F{sub 0}{sup a} is determined for 2 temperature scales (PLTS-2000 and Greywall). Contrarily to former measurements, the F{sub 0}{sup a} density dependence does not show any saturation at high pressures. (author)

  16. Aspects of Landau condensation in atomic physics

    International Nuclear Information System (INIS)

    Gay, J.C.

    1980-01-01

    Some aspects of Landau condensation in atomic physics are reviewed both as regards current work on Rydberg states under laboratory conditions and from the viewpoint of the prospects of spontaneous decay of neutral vacuum with superheavy elements. The characteristics of the hydrogen-atom spectrum in a strong magnetic field are presented and discussed using essentially semiclassical arguments. Some schematic attempt at a global interpretation of the Rydberg spectrum near the ionization limit is also given. Then the action of an electric field on the quasi-Landau spectrum is discussed. The conditions for spontaneous production of positrons from neutral vacuum decay with superheavy elements are reconsidered for the case when the system experiences ultrastrong magnetic fields, as in pulsars and white dwarfs. It is shown that spontaneous decay of neutral vacuum may occur at lower Z values than 169. The possible importance of such effects during heavy-ion collisions is briefly discussed. We deal with some qualitative trends of the problem of an atom in a magnetic field with particular emphasis on diamagnetic effects. In the last few years, we have had the capability of making accurate experimental investigations of Rydberg atoms, and perhaps in the future we will develop fundamentally new means of studying heavy-ion collisions. Accordingly it seems of interest to make qualitative remarks regarding the present state of the problem and the possible importance of Landau condensation in various domains of atomic physics now under active development. (author)

  17. Phase Diagram of the ν=5/2 Fractional Quantum Hall Effect: Effects of Landau-Level Mixing and Nonzero Width

    Directory of Open Access Journals (Sweden)

    Kiryl Pakrouski

    2015-04-01

    Full Text Available Interesting non-Abelian states, e.g., the Moore-Read Pfaffian and the anti-Pfaffian, offer candidate descriptions of the ν=5/2 fractional quantum Hall state. But, the significant controversy surrounding the nature of the ν=5/2 state has been hampered by the fact that the competition between these and other states is affected by small parameter changes. To study the phase diagram of the ν=5/2 state, we numerically diagonalize a comprehensive effective Hamiltonian describing the fractional quantum Hall effect of electrons under realistic conditions in GaAs semiconductors. The effective Hamiltonian takes Landau-level mixing into account to lowest order perturbatively in κ, the ratio of the Coulomb energy scale to the cyclotron gap. We also incorporate the nonzero width w of the quantum-well and subband mixing. We find the ground state in both the torus and spherical geometries as a function of κ and w. To sort out the nontrivial competition between candidate ground states, we analyze the following four criteria: its overlap with trial wave functions, the magnitude of energy gaps, the sign of the expectation value of an order parameter for particle-hole symmetry breaking, and the entanglement spectrum. We conclude that the ground state is in the universality class of the Moore-Read Pfaffian state, rather than the anti-Pfaffian, for κ<κ_{c}(w, where κ_{c}(w is a w-dependent critical value 0.6≲κ_{c}(w≲1. We observe that both Landau-level mixing and nonzero width suppress the excitation gap, but Landau-level mixing has a larger effect in this regard. Our findings have important implications for the identification of non-Abelian fractional quantum Hall states.

  18. A Landau fluid model for dissipative trapped electron modes

    International Nuclear Information System (INIS)

    Hedrick, C.L.; Leboeuf, J.N.; Sidikman, K.L.

    1995-09-01

    A Landau fluid model for dissipative trapped electron modes is developed which focuses on an improved description of the ion dynamics. The model is simple enough to allow nonlinear calculations with many harmonics for the times necessary to reach saturation. The model is motivated by a discussion that starts with the gyro-kinetic equation and emphasizes the importance of simultaneously including particular features of magnetic drift resonance, shear, and Landau effects. To ensure that these features are simultaneously incorporated in a Landau fluid model with only two evolution equations, a new approach to determining the closure coefficients is employed. The effect of this technique is to reduce the matching of fluid and kinetic responses to a single variable, rather than two, and to allow focusing on essential features of the fluctuations in question, rather than features that are only important for other types of fluctuations. Radially resolved nonlinear calculations of this model, advanced in time to reach saturation, are presented to partially illustrate its intended use. These calculations have a large number of poloidal and toroidal harmonics to represent the nonlinear dynamics in a converged steady state which includes cascading of energy to both short and long wavelengths

  19. Gyrokinetic linearized Landau collision operator

    DEFF Research Database (Denmark)

    Madsen, Jens

    2013-01-01

    , which is important in multiple ion-species plasmas. Second, the equilibrium operator describes drag and diffusion of the magnetic field aligned component of the vorticity associated with the E×B drift. Therefore, a correct description of collisional effects in turbulent plasmas requires the equilibrium......The full gyrokinetic electrostatic linearized Landau collision operator is calculated including the equilibrium operator, which represents the effect of collisions between gyrokinetic Maxwellian particles. First, the equilibrium operator describes energy exchange between different plasma species...... operator, even for like-particle collisions....

  20. Generalized Landau-Pollak uncertainty relation

    International Nuclear Information System (INIS)

    Miyadera, Takayuki; Imai, Hideki

    2007-01-01

    The Landau-Pollak uncertainty relation treats a pair of rank one projection valued measures and imposes a restriction on their probability distributions. It gives a nontrivial bound for summation of their maximum values. We give a generalization of this bound (weak version of the Landau-Pollak uncertainty relation). Our generalization covers a pair of positive operator valued measures. A nontrivial but slightly weak inequality that can treat an arbitrary number of positive operator valued measures is also presented. A possible application to the problem of separability criterion is also suggested

  1. Critical opalescence in fluids: 1.5-Scattering effects and the Landau-Placzek ratio

    OpenAIRE

    Sushko, M. Ya.

    2010-01-01

    We adduce new arguments for the significance of so-called 1.5- (or sesquialteral) molecular light scattering in one-component fluids. For this purpose, we analyze its effect on the Landau-Placzek ratio for the critical opalescence spectrum. The results obtained are used to reveal experimental data which can be interpreted as evidence for its existence and to evaluate both the relative magnitude and the sign of the 1.5-scattering contribution.

  2. Conformational landscape of an amyloid intra-cellular domain and Landau-Ginzburg-Wilson paradigm in protein dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Jin; He, Jianfeng, E-mail: Antti.Niemi@physics.uu.se, E-mail: hjf@bit.edu.cn [School of Physics, Beijing Institute of Technology, Beijing 100081 (China); Niemi, Antti J., E-mail: Antti.Niemi@physics.uu.se, E-mail: hjf@bit.edu.cn [School of Physics, Beijing Institute of Technology, Beijing 100081 (China); Department of Physics and Astronomy, Uppsala University, P.O. Box 803, S-75108 Uppsala (Sweden); Laboratoire de Mathematiques et Physique Theorique CNRS UMR 6083, Fédération Denis Poisson, Université de Tours, Parc de Grandmont, F37200 Tours (France)

    2016-07-28

    The Landau-Ginzburg-Wilson paradigm is proposed as a framework, to investigate the conformational landscape of intrinsically unstructured proteins. A universal Cα-trace Landau free energy is deduced from general symmetry considerations, with the ensuing all-atom structure modeled using publicly available reconstruction programs Pulchra and Scwrl. As an example, the conformational stability of an amyloid precursor protein intra-cellular domain (AICD) is inspected; the reference conformation is the crystallographic structure with code 3DXC in Protein Data Bank (PDB) that describes a heterodimer of AICD and a nuclear multi-domain adaptor protein Fe65. Those conformations of AICD that correspond to local or near-local minima of the Landau free energy are identified. For this, the response of the original 3DXC conformation to variations in the ambient temperature is investigated, using the Glauber algorithm. The conclusion is that in isolation the AICD conformation in 3DXC must be unstable. A family of degenerate conformations that minimise the Landau free energy is identified, and it is proposed that the native state of an isolated AICD is a superposition of these conformations. The results are fully in line with the presumed intrinsically unstructured character of isolated AICD and should provide a basis for a systematic analysis of AICD structure in future NMR experiments.

  3. Conformational landscape of an amyloid intra-cellular domain and Landau-Ginzburg-Wilson paradigm in protein dynamics

    International Nuclear Information System (INIS)

    Dai, Jin; He, Jianfeng; Niemi, Antti J.

    2016-01-01

    The Landau-Ginzburg-Wilson paradigm is proposed as a framework, to investigate the conformational landscape of intrinsically unstructured proteins. A universal Cα-trace Landau free energy is deduced from general symmetry considerations, with the ensuing all-atom structure modeled using publicly available reconstruction programs Pulchra and Scwrl. As an example, the conformational stability of an amyloid precursor protein intra-cellular domain (AICD) is inspected; the reference conformation is the crystallographic structure with code 3DXC in Protein Data Bank (PDB) that describes a heterodimer of AICD and a nuclear multi-domain adaptor protein Fe65. Those conformations of AICD that correspond to local or near-local minima of the Landau free energy are identified. For this, the response of the original 3DXC conformation to variations in the ambient temperature is investigated, using the Glauber algorithm. The conclusion is that in isolation the AICD conformation in 3DXC must be unstable. A family of degenerate conformations that minimise the Landau free energy is identified, and it is proposed that the native state of an isolated AICD is a superposition of these conformations. The results are fully in line with the presumed intrinsically unstructured character of isolated AICD and should provide a basis for a systematic analysis of AICD structure in future NMR experiments.

  4. Studies of electron correlation effects in multicharged ion atom collisions involving double capture

    Energy Technology Data Exchange (ETDEWEB)

    Stolterfoht, N.; Sommer, K.; Griffin, D.C.; Havener, C.C.; Huq, M.S.; Phaneuf, R.A.; Swenson, J.K.; Meyer, F.W.

    1988-01-01

    We review measurements of L-Coster Kronig and Auger electron production in slow, multicharged collision systems to study electron correlation effects in the process of double electron capture. The n/sup /minus/3/ law was confirmed for the production of the Coster-Kronig configurations 1s/sup 2/2pn/ell/ (n greater than or equal to 6) in O/sup 6 +/ + He collisions. Enhancement of high angular momentum /ell/ in specific 1s/sup 2/2pn/ell/ configurations was observed by means of high-resolution measurements of the Coster-Kronig lines. The importance of electron correlation effects in couplings of potential energy curves leading to the 1s/sup 2/2pn/ell/ configurations is verified by means of Landau-Zener model calculations. 32 refs., 4 figs.

  5. A ductile fracture criterion with Zener-Hollomon parameter of pure molybdenum sheet in thermal forming

    Directory of Open Access Journals (Sweden)

    Wang Chu

    2015-01-01

    Full Text Available Formability of pure molybdenum in thermal forming process has been greatly improved, but it is still hard to avoid the generation of rupture and other quality defects. In this paper, a ductile fracture criterion of pure molybdenum sheet in thermal forming was established by considering the plastic deformation capacity of material and stress states, which can be used to describe fracture behaviour and critical rupture prediction of pure molybdenum sheet during hot forming process. Based on the isothermal uniaxial tensile tests which performed at 993 to 1143 K with strain rate range from 0.0005 to 0.2 s−1, the material parameters are calculated by the combination method of experiment with FEsimulation. Based on the observation, new fracture criteria can be expressed as a function of Zener-Hollomon parameter. The critical fracture value that calculated by Oyane-Sato criterion increases with increasing temperature and decreasing strain rate. The ductile fracture criterion with Zener-Hollomon parameter of pure molybdenum in thermal forming is proposed.

  6. Landau-Zener tunneling with many-body quantum effects in crystals of molecular magnets

    OpenAIRE

    Fu, Li-Bin; Chen, Shi-Gang; Hu, Bambi

    2004-01-01

    We present a quantum interpretation of the heights in hysteresis of $Fe_{8}$ molecule at lower temperatures by treating the crystal as an Ising spin system with the dipolar interaction between spins. Then we apply it to two limit cases : rapid and adiabatic regions. Our theoretical analysis is in agreement with the experimental observation in these regions, which indicates that the steps in hysteresis loops of magnetization of Fe$_{8}$ at lower temperatures show a pure quantum process.

  7. Landau levels on a torus

    OpenAIRE

    Enrico OnofriDipartimento di Fisica, Universita` di Parma, and INFN, Gruppo Collegato di Parma, Parma, Italy

    2015-01-01

    Landau levels have represented a very rich field of research, which has gained widespread attention after their application to quantum Hall effect. In a particular gauge, the holomorphic gauge, they give a physical implementation of Bargmann's Hilbert space of entire functions. They have also been recognized as a natural bridge between Feynman's path integral and Geometric Quantization. We discuss here some mathematical subtleties involved in the formulation of the problem when one tries to s...

  8. Study of the heavy ions (Au+Au at 150 AMeV) collisions with the FOPI detector. Comparison with the Landau-Vlasov model; Etude des collisions d`ions lourds AU+AU a 150 A.MeV avec le detecteur FOPI. Comparaison avec le modele de Landau-Vlasov

    Energy Technology Data Exchange (ETDEWEB)

    Boussange, S

    1995-09-15

    In this thesis, heavy ions (Au+Au) collisions experiments are made at 150 AMeV.In the first part, a general study of the nuclear matter equation is presented. Then the used Landau-Vlasov theoretical model is describe. The third part presents the FOPI experience and the details of how to obtain this theoretical predictions (filter, cuts, corrections, possible centrality selections).At the end, experimental results and comparisons with the Landau-Vlasov model are presented. (TEC). 105 refs., 96 figs., 14 tabs.

  9. Dispersion relation and Landau damping of waves in high-energy density plasmas

    International Nuclear Information System (INIS)

    Zhu Jun; Ji Peiyong

    2012-01-01

    We present a theoretical investigation on the propagation of electromagnetic waves and electron plasma waves in high energy density plasmas using the covariant Wigner function approach. Based on the covariant Wigner function and Dirac equation, a relativistic quantum kinetic model is established to describe the physical processes in high-energy density plasmas. With the zero-temperature Fermi–Dirac distribution, the dispersion relation and Landau damping of waves containing the relativistic quantum corrected terms are derived. The relativistic quantum corrections to the dispersion relation and Landau damping are analyzed by comparing our results with those obtained in classical and non-relativistic quantum plasmas. We provide a detailed discussion on the Landau damping obtained in classical plasmas, non-relativistic Fermi plasmas and relativistic Fermi plasmas. The contributions of the Bohm potential, the Fermi statistics pressure and relativistic effects to the dispersion relation and Landau damping of waves are quantitatively calculated with real plasma parameters. (paper)

  10. Fermi liquid, clustering, and structure factor in dilute warm nuclear matter

    Science.gov (United States)

    Röpke, G.; Voskresensky, D. N.; Kryukov, I. A.; Blaschke, D.

    2018-02-01

    Properties of nuclear systems at subsaturation densities can be obtained from different approaches. We demonstrate the use of the density autocorrelation function which is related to the isothermal compressibility and, after integration, to the equation of state. This way we connect the Landau Fermi liquid theory well elaborated in nuclear physics with the approaches to dilute nuclear matter describing cluster formation. A quantum statistical approach is presented, based on the cluster decomposition of the polarization function. The fundamental quantity to be calculated is the dynamic structure factor. Comparing with the Landau Fermi liquid theory which is reproduced in lowest approximation, the account of bound state formation and continuum correlations gives the correct low-density result as described by the second virial coefficient and by the mass action law (nuclear statistical equilibrium). Going to higher densities, the inclusion of medium effects is more involved compared with other quantum statistical approaches, but the relation to the Landau Fermi liquid theory gives a promising approach to describe not only thermodynamic but also collective excitations and non-equilibrium properties of nuclear systems in a wide region of the phase diagram.

  11. On Landau damping

    KAUST Repository

    Mouhot, Clément

    2011-09-01

    Going beyond the linearized study has been a longstanding problem in the theory of Landau damping. In this paper we establish exponential Landau damping in analytic regularity. The damping phenomenon is reinterpreted in terms of transfer of regularity between kinetic and spatial variables, rather than exchanges of energy; phase mixing is the driving mechanism. The analysis involves new families of analytic norms, measuring regularity by comparison with solutions of the free transport equation; new functional inequalities; a control of non-linear echoes; sharp "deflection" estimates; and a Newton approximation scheme. Our results hold for any potential no more singular than Coulomb or Newton interaction; the limit cases are included with specific technical effort. As a side result, the stability of homogeneous equilibria of the non-linear Vlasov equation is established under sharp assumptions. We point out the strong analogy with the KAM theory, and discuss physical implications. Finally, we extend these results to some Gevrey (non-analytic) distribution functions. © 2011 Institut Mittag-Leffler.

  12. Identifying Mechanical Properties of Viscoelastic Materials in Time Domain Using the Fractional Zener Model

    Directory of Open Access Journals (Sweden)

    Ana Paula Delowski Ciniello

    Full Text Available Abstract The present paper aims at presenting a methodology for characterizing viscoelastic materials in time domain, taking into account the fractional Zener constitutive model and the influence of temperature through Williams, Landel, and Ferry’s model. To that effect, a set of points obtained experimentally through uniaxial tensile tests with different constant strain rates is considered. The approach is based on the minimization of the quadratic relative distance between the experimental stress-strain curves and the corresponding ones given by the theoretical model. In order to avoid the local minima in the process of optimization, a hybrid technique based on genetic algorithms and non-linear programming techniques is used. The methodology is applied in the characterization of two different commercial viscoelastic materials. The results indicate that the proposed methodology is effective in identifying thermorheologically simple viscoelastic materials.

  13. Effects of periodic scattering potential on Landau quantization and ballistic transport of electrons in graphene

    Energy Technology Data Exchange (ETDEWEB)

    Gumbs, Godfrey [Department of Physics and Astronomy, Hunter College, CUNY, 695 Park Avenue, New York, NY 10065, USA and Donostia International Physics Center (DIPC), P de Manuel Lardizabal, 4, 20018 San Sebastian, Basque Country (Spain); Iurov, Andrii [Department of Physics and Astronomy, Hunter College of the City University of New York, 695 Park Avenue, New York, NY 10065 (United States); Huang, Danhong [Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, NM 87117 (United States); Fekete, Paula [West Point Military Academy, West Point, NY (United States); Zhemchuzhna, Liubov [Department of Physics, North Carolina Central University, Durham, North Carolina 27707 (United States)

    2014-03-31

    A two-dimensional periodic array of scatterers has been introduced to a single layer of graphene in the presence of an external magnetic field perpendicular to the graphene layer. The eigenvalue equation for such a system has been solved numerically to display the structure of split Landau subbands as functions of both wave number and magnetic flux. The effects of pseudo-spin coupling and Landau subbands mixing by a strong scattering potential have been demonstrated. Additionally, we investigated the square barrier tunneling problem when magnetic field is present, as well as demonstrate the crucial difference in the modulated band structure between graphene and the two-dimensional electron gas. The low-magnetic field regime is particularly interesting for Dirac fermions and has been discussed. Tunneling of Dirac electrons through a magnetic potential barrier has been investigated to complement the reported results on electrostatic potential scattering in the presence of an ambient magnetic field.

  14. Effects of periodic scattering potential on Landau quantization and ballistic transport of electrons in graphene

    International Nuclear Information System (INIS)

    Gumbs, Godfrey; Iurov, Andrii; Huang, Danhong; Fekete, Paula; Zhemchuzhna, Liubov

    2014-01-01

    A two-dimensional periodic array of scatterers has been introduced to a single layer of graphene in the presence of an external magnetic field perpendicular to the graphene layer. The eigenvalue equation for such a system has been solved numerically to display the structure of split Landau subbands as functions of both wave number and magnetic flux. The effects of pseudo-spin coupling and Landau subbands mixing by a strong scattering potential have been demonstrated. Additionally, we investigated the square barrier tunneling problem when magnetic field is present, as well as demonstrate the crucial difference in the modulated band structure between graphene and the two-dimensional electron gas. The low-magnetic field regime is particularly interesting for Dirac fermions and has been discussed. Tunneling of Dirac electrons through a magnetic potential barrier has been investigated to complement the reported results on electrostatic potential scattering in the presence of an ambient magnetic field

  15. Bargmann representation for Landau levels in two dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Rohringer, Nina [Institute for Theoretical Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, A-1040 Vienna (Austria); Burgdoerfer, Joachim [Institute for Theoretical Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, A-1040 Vienna (Austria); Macris, Nicolas [Institut de Physique Theorique, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland)

    2003-04-11

    We present a formulation of the quantum mechanics of an electron gas confined to two dimensions in a strong magnetic field within the framework of the Hilbert space of analytic functions (Bargmann's space). Our approach extends the representation introduced by Girvin and Jach for the ground state to arbitrary Landau levels and to the regime of coupling between Landau levels. By projecting out the rapid cyclotron motion, the quantum mechanics of the slow guiding centre motion is converted into a system of coupled-channel equations describing the coupling between Landau levels due to the (disorder) potentials. In the limit of strong fields, the coupled-channel equations can be solved perturbatively. For the single-channel case we derive a WKB-like quantization condition for the one-dimensional motion along equipotential lines for arbitrary Landau levels. Two applications of this formalism are discussed: the weak-levitation problem in quantum Hall systems and a two-electron quantum dot in a strong magnetic field.

  16. Bargmann representation for Landau levels in two dimensions

    International Nuclear Information System (INIS)

    Rohringer, Nina; Burgdoerfer, Joachim; Macris, Nicolas

    2003-01-01

    We present a formulation of the quantum mechanics of an electron gas confined to two dimensions in a strong magnetic field within the framework of the Hilbert space of analytic functions (Bargmann's space). Our approach extends the representation introduced by Girvin and Jach for the ground state to arbitrary Landau levels and to the regime of coupling between Landau levels. By projecting out the rapid cyclotron motion, the quantum mechanics of the slow guiding centre motion is converted into a system of coupled-channel equations describing the coupling between Landau levels due to the (disorder) potentials. In the limit of strong fields, the coupled-channel equations can be solved perturbatively. For the single-channel case we derive a WKB-like quantization condition for the one-dimensional motion along equipotential lines for arbitrary Landau levels. Two applications of this formalism are discussed: the weak-levitation problem in quantum Hall systems and a two-electron quantum dot in a strong magnetic field

  17. Bargmann representation for Landau levels in two dimensions

    CERN Document Server

    Rohringer, N; Macris, N

    2003-01-01

    We present a formulation of the quantum mechanics of an electron gas confined to two dimensions in a strong magnetic field within the framework of the Hilbert space of analytic functions (Bargmann's space). Our approach extends the representation introduced by Girvin and Jach for the ground state to arbitrary Landau levels and to the regime of coupling between Landau levels. By projecting out the rapid cyclotron motion, the quantum mechanics of the slow guiding centre motion is converted into a system of coupled-channel equations describing the coupling between Landau levels due to the (disorder) potentials. In the limit of strong fields, the coupled-channel equations can be solved perturbatively. For the single-channel case we derive a WKB-like quantization condition for the one-dimensional motion along equipotential lines for arbitrary Landau levels. Two applications of this formalism are discussed: the weak-levitation problem in quantum Hall systems and a two-electron quantum dot in a strong magnetic field...

  18. Topological approach to quantum Hall effects and its important applications: higher Landau levels, graphene and its bilayer

    Science.gov (United States)

    Jacak, Janusz; Łydżba, Patrycja; Jacak, Lucjan

    2017-05-01

    In this paper the topological approach to quantum Hall effects is carefully described. Commensurability conditions together with proposed generators of a system braid group are employed to establish the fractional quantum Hall effect hierarchies of conventional semiconductors, monolayer and bilayer graphene structures. Obtained filling factors are compared with experimental data and a very good agreement is achieved. Preliminary constructions of ground-state wave functions in the lowest Landau level are put forward. Furthermore, this work explains why pyramids of fillings from higher bands are not counterparts of the well-known composite-fermion hierarchy - it provides with the cause for an intriguing robustness of ν = 7/3 , 8/3 and 5/2 states (also in graphene). The argumentation why paired states can be developed in two-subband systems (wide quantum wells) only when the Fermi energy lies in the first Landau level is specified. Finally, the paper also clarifies how an additional surface in bilayer systems contributes to an observation of the fractional quantum Hall effect near half-filling, ν = 1/2 .

  19. The effect of boundaries on the asymptotic wavenumber of spiral wave solutions of the complex Ginzburg–Landau equation

    KAUST Repository

    Aguareles, M.

    2014-01-01

    In this paper we consider an oscillatory medium whose dynamics are modeled by the complex Ginzburg-Landau equation. In particular, we focus on n-armed spiral wave solutions of the complex Ginzburg-Landau equation in a disk of radius d

  20. On the effects on a Landau-type system for an atom with no permanent electric dipole moment due to a Coulomb-type potential

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Abinael B.; Bakke, Knut, E-mail: kbakke@fisica.ufpb.br

    2016-02-15

    We analyse the bound states for a Landau-type system for an atom with no permanent electric dipole moment subject to a Coulomb-type potential. By comparing the energy levels for bound states of the system with the Landau quantization for an atom with no permanent electric dipole moment (Furtado et al., 2006), we show that the energy levels of the Landau-type system are modified, where the degeneracy of the energy levels is broken. Another quantum effect investigated is a dependence of the angular frequency of the system on the quantum numbers associated with the radial modes and the angular momentum. As examples, we obtain the angular frequency and the energy levels associated with the ground state and the first excited state of the system.

  1. On the effects on a Landau-type system for an atom with no permanent electric dipole moment due to a Coulomb-type potential

    International Nuclear Information System (INIS)

    Oliveira, Abinael B.; Bakke, Knut

    2016-01-01

    We analyse the bound states for a Landau-type system for an atom with no permanent electric dipole moment subject to a Coulomb-type potential. By comparing the energy levels for bound states of the system with the Landau quantization for an atom with no permanent electric dipole moment (Furtado et al., 2006), we show that the energy levels of the Landau-type system are modified, where the degeneracy of the energy levels is broken. Another quantum effect investigated is a dependence of the angular frequency of the system on the quantum numbers associated with the radial modes and the angular momentum. As examples, we obtain the angular frequency and the energy levels associated with the ground state and the first excited state of the system.

  2. The rubber band revisited: Wang–Landau simulation

    International Nuclear Information System (INIS)

    Ferreira, Lucas S; Caparica, Álvaro A; Neto, Minos A; Galiceanu, Mircea D

    2012-01-01

    In this work we apply Wang–Landau simulations to a simple model which has exact solutions both in the microcanonical and canonical formalisms. The simulations were carried out by using an updated version of the Wang–Landau sampling. We consider a homopolymer chain consisting of N monomers units which may assume any configuration on the two-dimensional lattice. By imposing constraints to the moves of the polymers we obtain three different models. Our results show that updating the density of states only after every N monomer moves leads to a better precision. We obtain the specific heat and the end-to-end distance per monomer and test the precision of our simulations by comparing the location of the maximum of the specific heat with the exact results and conventional Wang–Landau simulations for the three types of walk. (paper)

  3. Nonlinear damping of oblique whistler mode waves through Landau resonance

    Science.gov (United States)

    Hsieh, Y.; Omura, Y.

    2017-12-01

    Nonlinear trapping of electrons through Landau resonance is a characteristic dynamics in oblique whistler-mode wave particle interactions. The resonance velocity of the Landau resonance at quasi-parallel propagation becomes very close to the parallel group velocity of whistler-mode wave at frequency around 0.5 Ωe, causing a long distance of resonant interaction and strong acceleration of resonant electrons [1]. We demonstrate these effective accelerations for electrons with high equatorial pitch angle ( > 60°) by test particle simulations with parameters for the Earth's inner magnetosphere at L=5. In the simulations, we focus on slightly oblique whistler mode waves with wave normal angle 10.1002/2016JA023255.

  4. Bounce-harmonic Landau Damping of Plasma Waves

    Science.gov (United States)

    Anderegg, Francois

    2015-11-01

    We present measurement of plasma wave damping, spanning the temperature regimes of direct Landau damping, bounce-harmonic Landau damping, inter-species drag damping, and viscous damping. Direct Landau damping is dominant at high temperatures, but becomes negligible as v vph / 5 . The measurements are conducted in trapped pure ion plasmas contained in Penning-Malmberg trap, with wave-coherent LIF diagnostics of particle velocities. Our focus is on bounce harmonics damping, controlled by an applied ``squeeze'' potential, which generates harmonics in the wave potential and in the particle dynamics. A particle moving in z experiences a non-sinusoidal mode potential caused by the squeeze, producing high spatial harmonics with lower phase velocity. These harmonics are Landau damped even when the mode phase velocity vph is large compared to the thermal velocity v , since the nth harmonic is resonant with a particle bouncing at velocity vb =vph / n . Here we increase the bounce harmonics through applied squeeze potential; but some harmonics are always present in finite length systems. For our centered squeeze geometry, theory shows that only odd harmonics are generated, and predicts the Landau damping rate from vph / n . Experimentally, the squeeze potential increases the wave damping and reduces its frequency. The frequency shift occurs because the squeeze potential reduces the number of particle where the mode velocity is the largest, therefore reducing the mode frequency. We observe an increase in the damping proportional to Vs2,and a frequency reduction proportional to Vs , in quantitative agreement with theory. Wave-coherent laser induced fluorescence allows direct observation of bounce resonances on the particle distribution, here predominantly at vph / 3 . A clear increase of the bounce harmonics is visible on the particle distribution when the squeeze potential is applied. Supported by NSF Grant PHY-1414570, and DOE Grants DE-SC0002451 and DE-SC0008693.

  5. The effect of boundaries on the asymptotic wavenumber of spiral wave solutions of the complex Ginzburg–Landau equation

    KAUST Repository

    Aguareles, M.

    2014-06-01

    In this paper we consider an oscillatory medium whose dynamics are modeled by the complex Ginzburg-Landau equation. In particular, we focus on n-armed spiral wave solutions of the complex Ginzburg-Landau equation in a disk of radius d with homogeneous Neumann boundary conditions. It is well-known that such solutions exist for small enough values of the twist parameter q and large enough values of d. We investigate the effect of boundaries on the rotational frequency of the spirals, which is an unknown of the problem uniquely determined by the parameters d and q. We show that there is a threshold in the parameter space where the effect of the boundary on the rotational frequency switches from being algebraic to exponentially weak. We use the method of matched asymptotic expansions to obtain explicit expressions for the asymptotic wavenumber as a function of the twist parameter and the domain size for small values of q. © 2014 Elsevier B.V. All rights reserved.

  6. The Rubber Band Revisited: Wang-Landau Simulation

    OpenAIRE

    Ferreira, Lucas S.; Caparica, Alvaro A.; Neto, Minos A.; Galiceanu, Mircea D.

    2012-01-01

    In this work we apply Wang-Landau simulations to a simple model which has exact solutions both in the microcanonical and canonical formalisms. The simulations were carried out by using an updated version of the Wang-Landau sampling. We consider a homopolymer chain consisting of $N$ monomers units which may assume any configuration on the two-dimensional lattice. By imposing constraints to the moves of the polymers we obtain three different models. Our results show that updating the density of...

  7. Possibility of Landau damping of gravitational waves

    International Nuclear Information System (INIS)

    Gayer, S.; Kennel, C.F.

    1979-01-01

    There is considerable uncertainty in the literature concerning whether or not transverse traceless gravitational waves can Landau damp. Physically, the issue is whether particles of nonzero mass can comove with surfaces of constant wave phase, and therefore, loosely, whether gravitational waves can have phase speeds less than that of light. We approach the question of Landau damping in various ways. We consider first the propagation of small-amplitude gravitational waves in an ideal fluid-filled Robertson-Walker universe of zero spatial curvature. We argue that the principle of equivalence requires those modes to be lightlike. We show that a freely moving particle interacting only with the collective fields cannot comove with such waves if it has nonzero mass. The equation for gravitational waves in collisionless kinetic gases differs from that for fluid media only by terms so small that deviations from lightlike propagation are unmeasurable. Thus, we conclude that Landau damping of small-amplitude, transverse traceless gravitational waves is not possible

  8. The effect of exchange interaction on quasiparticle Landau levels in narrow-gap quantum well heterostructures.

    Science.gov (United States)

    Krishtopenko, S S; Gavrilenko, V I; Goiran, M

    2012-04-04

    Using the 'screened' Hartree-Fock approximation based on the eight-band k·p Hamiltonian, we have extended our previous work (Krishtopenko et al 2011 J. Phys.: Condens. Matter 23 385601) on exchange enhancement of the g-factor in narrow-gap quantum well heterostructures by calculating the exchange renormalization of quasiparticle energies, the density of states at the Fermi level and the quasiparticle g-factor for different Landau levels overlapping. We demonstrate that exchange interaction yields more pronounced Zeeman splitting of the density of states at the Fermi level and leads to the appearance of peak-shaped features in the dependence of the Landau level energies on the magnetic field at integer filling factors. We also find that the quasiparticle g-factor does not reach the maximum value at odd filling factors in the presence of large overlapping of spin-split Landau levels. We advance an argument that the behavior of the quasiparticle g-factor in weak magnetic fields is defined by a random potential of impurities in narrow-gap heterostructures. © 2012 IOP Publishing Ltd

  9. Ginzburg-Landau theory of the superheating field anisotropy of layered superconductors

    Science.gov (United States)

    Liarte, Danilo B.; Transtrum, Mark K.; Sethna, James P.

    2016-10-01

    We investigate the effects of material anisotropy on the superheating field of layered superconductors. We provide an intuitive argument both for the existence of a superheating field, and its dependence on anisotropy, for κ =λ /ξ (the ratio of magnetic to superconducting healing lengths) both large and small. On the one hand, the combination of our estimates with published results using a two-gap model for MgB2 suggests high anisotropy of the superheating field near zero temperature. On the other hand, within Ginzburg-Landau theory for a single gap, we see that the superheating field shows significant anisotropy only when the crystal anisotropy is large and the Ginzburg-Landau parameter κ is small. We then conclude that only small anisotropies in the superheating field are expected for typical unconventional superconductors near the critical temperature. Using a generalized form of Ginzburg Landau theory, we do a quantitative calculation for the anisotropic superheating field by mapping the problem to the isotropic case, and present a phase diagram in terms of anisotropy and κ , showing type I, type II, or mixed behavior (within Ginzburg-Landau theory), and regions where each asymptotic solution is expected. We estimate anisotropies for a number of different materials, and discuss the importance of these results for radio-frequency cavities for particle accelerators.

  10. Magnetic field-induced Landau Fermi liquid in high-T{sub c} metals

    Energy Technology Data Exchange (ETDEWEB)

    Amusia, M.Ya.; Shaginyan, V.R

    2003-08-25

    We consider the behavior of strongly correlated electron liquid in high-temperature superconductors within the framework of the fermion condensation model. We show that at low temperatures the normal state recovered by the application of a magnetic field larger than the critical field can be viewed as the Landau Fermi liquid induced by the magnetic field. In this state, the Wiedemann-Franz law and the Korringa law are held and the elementary excitations are the Landau Fermi liquid quasiparticles. Contrary to what might be expected from the Landau theory, the effective mass of quasiparticles depends on the magnetic field. The recent experimental verifications of the Wiedemann-Franz law in heavily hole-overdoped, overdoped and optimally doped cuprates and the verification of the Korringa law in the electron-doped copper oxide superconductor strongly support the existence of fermion condensate in high-T{sub c} metals.

  11. Breaking the hidden symmetry in the Ginzburg-Landau equation

    NARCIS (Netherlands)

    Doelman, A.

    1997-01-01

    In this paper we study localised, traveling, solutions to a Ginzburg-Landau equation to which we have added a small, O ( " ), 0 < "? 1, quintic term. We consider this term as a model for the higher order nonlinearities which appear in the derivation of the Ginzburg-Landau equation. By a combination

  12. Adaptive resummation of Markovian quantum dynamics

    International Nuclear Information System (INIS)

    Lucas, Felix

    2014-01-01

    In this thesis we derive a highly convergent, nonperturbative expansion of Markovian open quantum dynamics. It is based on a splitting of the incoherent dynamics into periods of continuous evolution and abrupt jumps and attains its favorable convergence properties from an adaptive resummation of this so-called jump expansion. By means of the long-standing problems of spatial particle detection and Landau-Zener tunneling in the presence of dephasing, we show that this adaptive resummation technique facilitates new highly accurate analytic approximations of Markovian open systems. The open Landau-Zener model leads us to propose an efficient and robust incoherent control technique for the isomerization reaction of the visual pigment protein rhodopsin. Besides leading to approximate analytic descriptions of Markovian open quantum dynamics, the adaptive resummation of the jump expansion implies an efficient numerical simulation method. We spell out the corresponding numerical algorithm by means of Monte Carlo integration of the relevant terms in the jump expansion and demonstrate it in a set of paradigmatic open quantum systems.

  13. Breaking the hidden symmetry in the Ginzburg-Landau equation

    NARCIS (Netherlands)

    Doelman, A.

    1996-01-01

    In this paper we study localised, traveling, solutions to a Ginzburg-Landau equation to which we have added a small, O(e), 0 < e << 1, quintic term. We consider this term as a model for the higher order nonlinearities which appear in the derivation of the Ginzburg-Landau equation. By a combination

  14. Evolutionary algorithms applied to Landau-gauge fixing

    International Nuclear Information System (INIS)

    Markham, J.F.

    1998-01-01

    Current algorithms used to put a lattice gauge configuration into Landau gauge either suffer from the problem of critical slowing-down or involve an additions computational expense to overcome it. Evolutionary Algorithms (EAs), which have been widely applied to other global optimisation problems, may be of use in gauge fixing. Also, being global, they should not suffer from critical slowing-down as do local gradient based algorithms. We apply EA'S and also a Steepest Descent (SD) based method to the problem of Landau Gauge Fixing and compare their performance. (authors)

  15. Geometric singularities and spectra of Landau-Ginzburg models

    International Nuclear Information System (INIS)

    Greene, B.R.; Roan, S.S.; Yau, S.T.

    1991-01-01

    Some mathematical and physical aspects of superconformal string compactification in weighted projective space are discussed. In particular, we recast the path integral argument establishing the connection between Landau-Ginsburg conformal theories and Calabi-Yau string compactification in a geometric framework. We then prove that the naive expression for the vanishing of the first Chern class for a complete intersection (adopted from the smooth case) is sufficient to ensure that the resulting variety, which is generically singular, can be resolved to a smooth Calabi-Yau space. This justifies much analysis which has recently been expended on the study of Landau-Ginzburg models. Furthermore, we derive some simple formulae for the determination of the Witten index in these theories which are complementary to those derived using semiclassical reasoning by Vafa. Finally, we also comment on the possible geometrical significance of unorbifolded Landau-Ginzburg theories. (orig.)

  16. Towards a generalized Landau theory of quasi-particles for hot dense matter

    International Nuclear Information System (INIS)

    Leermakers, R.

    1985-01-01

    In this thesis it is tried to construct a Landau quasi-particle theory for relativistic systems, using field-theoretical methods. It includes a perturbative calculation of the pressure of a quark-gluon plasma. It reports the existence of a hitherto unnoticed plasmon contribution of the order g 3 due to transverse quasi-gluons. A new and Lorentz covariant formulation of the Landau theory is being developed, for a general relativistic system. A detailed calculation is presented of the observables of a quantum electrodynamical (QED) plasma, in lowest orders of perturbation theory. A transverse plasmon effect is discovered, both analytically and numerically. In addition, the analysis shows quasi-electrons and positrons to be stable excitations at any temperature. This is proven in all orders of perturbation theory. Along with a Landau theory for quark-gluon matter, a linearized kinetic equation is derived for the singlet quark distribution function, with a collision term for soft encounters between quasi-quarks. (Auth.)

  17. Decoherence in a scalable adiabatic quantum computer

    International Nuclear Information System (INIS)

    Ashhab, S.; Johansson, J. R.; Nori, Franco

    2006-01-01

    We consider the effects of decoherence on Landau-Zener crossings encountered in a large-scale adiabatic-quantum-computing setup. We analyze the dependence of the success probability--i.e., the probability for the system to end up in its new ground state--on the noise amplitude and correlation time. We determine the optimal sweep rate that is required to maximize the success probability. We then discuss the scaling of decoherence effects with increasing system size. We find that those effects can be important for large systems, even if they are small for each of the small building blocks

  18. Quantum corrections to nonlinear ion acoustic wave with Landau damping

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, Abhik; Janaki, M. S. [Saha Institute of Nuclear Physics, Calcutta (India); Bose, Anirban [Serampore College, West Bengal (India)

    2014-07-15

    Quantum corrections to nonlinear ion acoustic wave with Landau damping have been computed using Wigner equation approach. The dynamical equation governing the time development of nonlinear ion acoustic wave with semiclassical quantum corrections is shown to have the form of higher KdV equation which has higher order nonlinear terms coming from quantum corrections, with the usual classical and quantum corrected Landau damping integral terms. The conservation of total number of ions is shown from the evolution equation. The decay rate of KdV solitary wave amplitude due to the presence of Landau damping terms has been calculated assuming the Landau damping parameter α{sub 1}=√(m{sub e}/m{sub i}) to be of the same order of the quantum parameter Q=ℏ{sup 2}/(24m{sup 2}c{sub s}{sup 2}L{sup 2}). The amplitude is shown to decay very slowly with time as determined by the quantum factor Q.

  19. Theoretical studies of multistep processes, isospin effects in nuclear scattering, and meson and baryon interactions in nuclear physics: Annual progess report, 1 May 1988--30 April 1989

    International Nuclear Information System (INIS)

    Landau, R.H.; Madsen, V.A.

    1988-01-01

    A progress report is presented for DOE grant FG06-86ER40283 supporting theoretical studies in nuclear and particle physics at Oregon State University. The research was led by Professors Landau and Madsen, and carried out in collaboration with graduate students in Corvallis, and scientists at LLNL-Livermore, TRIUMF, KFA-Juelich, Purdue University, and Florida State University. The studies include meson-exchange-current effects, quark effects, and relativistic (Dirac) effects deduced from spin observables in p- 3 He scattering, atomic and nuclear Gamow states in momentum space of kaons and antiprotons, and charge-symmetry violation in pion scattering. Additional studies include microscopic optical potential calculations, multiple step processes, and differences in neutron and proton multipole matrix elements and transition densities in low lying collective states and in giant resonances. 13 refs

  20. Landau levels and magneto-transport property of monolayer phosphorene

    Science.gov (United States)

    Zhou, X. Y.; Zhang, R.; Sun, J. P.; Zou, Y. L.; Zhang, D.; Lou, W. K.; Cheng, F.; Zhou, G. H.; Zhai, F.; Chang, Kai

    2015-01-01

    We investigate theoretically the Landau levels (LLs) and magneto-transport properties of phosphorene under a perpendicular magnetic field within the framework of the effective k·p Hamiltonian and tight-binding (TB) model. At low field regime, we find that the LLs linearly depend both on the LL index n and magnetic field B, which is similar with that of conventional semiconductor two-dimensional electron gas. The Landau splittings of conduction and valence band are different and the wavefunctions corresponding to the LLs are strongly anisotropic due to the different anisotropic effective masses. An analytical expression for the LLs in low energy regime is obtained via solving the decoupled Hamiltonian, which agrees well with the numerical calculations. At high magnetic regime, a self-similar Hofstadter butterfly (HB) spectrum is obtained by using the TB model. The HB spectrum is consistent with the LL fan calculated from the effective k·p theory in a wide regime of magnetic fields. We find the LLs of phosphorene nanoribbon depend strongly on the ribbon orientation due to the anisotropic hopping parameters. The Hall and the longitudinal conductances (resistances) clearly reveal the structure of LLs. PMID:26159856

  1. Ginzburg-Landau equation and vortex liquid phase of Fermi liquid superconductors

    International Nuclear Information System (INIS)

    Ng, T-K; Tse, W-T

    2007-01-01

    In this paper we study the Ginzburg-Landau (GL) equation for Fermi liquid superconductors with strong Landau interactions F 0s and F 1s . We show that Landau interactions renormalize two parameters entering the GL equation, leading to the renormalization of the compressibility and superfluid density. The renormalization of the superfluid density in turn leads to an unconventional (2D) Berezinskii-Kosterlitz-Thouless (BKT) transition and vortex liquid phase. Application of the GL equation to describe underdoped high-T c cuprates is discussed

  2. Raise and collapse of pseudo Landau levels in graphene

    Science.gov (United States)

    Castro, Eduardo V.; Cazalilla, Miguel A.; Vozmediano, María A. H.

    2017-12-01

    Lattice deformations couple to the low-energy electronic excitations of graphene as vector fields similar to the electromagnetic potential. The observation of strain-induced pseudo Landau levels with scanning tunnel microscopy experiments has been one of the most exciting events in the history of graphene. Nevertheless, the experimental observation presents some ambiguities. Similar strain patterns show different images that are sometimes difficult to interpret. In this Rapid Communication, we show that, for some strain configurations, the deformation potential acts as a parallel electric field able to destabilize the Landau level structure via a mechanism identical to that occurring for real electromagnetic fields. This effect also alters the estimations of the value of the pseudomagnetic field, which can be significantly bigger. The mechanism applies equally if the electric field has an external origin, which opens the door to an electric control of giant pseudomagnetic fields in graphene.

  3. Landau Levels of Majorana Fermions in a Spin Liquid.

    Science.gov (United States)

    Rachel, Stephan; Fritz, Lars; Vojta, Matthias

    2016-04-22

    Majorana fermions, originally proposed as elementary particles acting as their own antiparticles, can be realized in condensed-matter systems as emergent quasiparticles, a situation often accompanied by topological order. Here we propose a physical system which realizes Landau levels-highly degenerate single-particle states usually resulting from an orbital magnetic field acting on charged particles-for Majorana fermions. This is achieved in a variant of a quantum spin system due to Kitaev which is distorted by triaxial strain. This strained Kitaev model displays a spin-liquid phase with charge-neutral Majorana-fermion excitations whose spectrum corresponds to that of Landau levels, here arising from a tailored pseudomagnetic field. We show that measuring the dynamic spin susceptibility reveals the Landau-level structure by a remarkable mechanism of probe-induced bound-state formation.

  4. Tensor Fermi liquid parameters in nuclear matter from chiral effective field theory

    Science.gov (United States)

    Holt, J. W.; Kaiser, N.; Whitehead, T. R.

    2018-05-01

    We compute from chiral two- and three-body forces the complete quasiparticle interaction in symmetric nuclear matter up to twice nuclear matter saturation density. Second-order perturbative contributions that account for Pauli blocking and medium polarization are included, allowing for an exploration of the full set of central and noncentral operator structures permitted by symmetries and the long-wavelength limit. At the Hartree-Fock level, the next-to-next-to-leading order three-nucleon force contributes to all noncentral interactions, and their strengths grow approximately linearly with the nucleon density up to that of saturated nuclear matter. Three-body forces are shown to enhance the already strong proton-neutron effective tensor interaction, while the corresponding like-particle tensor force remains small. We also find a large isovector cross-vector interaction but small center-of-mass tensor interactions in the isoscalar and isovector channels. The convergence of the expansion of the noncentral quasiparticle interaction in Landau parameters and Legendre polynomials is studied in detail.

  5. A graphene Zener-Klein transistor cooled by a hyperbolic substrate

    Science.gov (United States)

    Yang, Wei; Berthou, Simon; Lu, Xiaobo; Wilmart, Quentin; Denis, Anne; Rosticher, Michael; Taniguchi, Takashi; Watanabe, Kenji; Fève, Gwendal; Berroir, Jean-Marc; Zhang, Guangyu; Voisin, Christophe; Baudin, Emmanuel; Plaçais, Bernard

    2018-01-01

    The engineering of cooling mechanisms is a bottleneck in nanoelectronics. Thermal exchanges in diffusive graphene are mostly driven by defect-assisted acoustic phonon scattering, but the case of high-mobility graphene on hexagonal boron nitride (hBN) is radically different, with a prominent contribution of remote phonons from the substrate. Bilayer graphene on a hBN transistor with a local gate is driven in a regime where almost perfect current saturation is achieved by compensation of the decrease in the carrier density and Zener-Klein tunnelling (ZKT) at high bias. Using noise thermometry, we show that the ZKT triggers a new cooling pathway due to the emission of hyperbolic phonon polaritons in hBN by out-of-equilibrium electron-hole pairs beyond the super-Planckian regime. The combination of ZKT transport and hyperbolic phonon polariton cooling renders graphene on BN transistors a valuable nanotechnology for power devices and RF electronics.

  6. Landau quantization effects on hole-acoustic instability in semiconductor plasmas

    Science.gov (United States)

    Sumera, P.; Rasheed, A.; Jamil, M.; Siddique, M.; Areeb, F.

    2017-12-01

    The growth rate of the hole acoustic waves (HAWs) exciting in magnetized semiconductor quantum plasma pumped by the electron beam has been investigated. The instability of the waves contains quantum effects including the exchange and correlation potential, Bohm potential, Fermi-degenerate pressure, and the magnetic quantization of semiconductor plasma species. The effects of various plasma parameters, which include relative concentration of plasma particles, beam electron temperature, beam speed, plasma temperature (temperature of electrons/holes), and Landau electron orbital magnetic quantization parameter η, on the growth rate of HAWs, have been discussed. The numerical study of our model of acoustic waves has been applied, as an example, to the GaAs semiconductor exposed to electron beam in the magnetic field environment. An increment in either the concentration of the semiconductor electrons or the speed of beam electrons, in the presence of magnetic quantization of fermion orbital motion, enhances remarkably the growth rate of the HAWs. Although the growth rate of the waves reduces with a rise in the thermal temperature of plasma species, at a particular temperature, we receive a higher instability due to the contribution of magnetic quantization of fermions to it.

  7. Nucleon molecular orbitals and the transition mechanism between molecular orbitals in nucleus-nucleus collisions

    International Nuclear Information System (INIS)

    Imanishi, B.; Misono, S.; von Oertzen, W.; Voit, H.

    1988-08-01

    The molecular orbitals of the nucleon(s) in nucleus-nucleus collisions are dynamically defined as a linear combination of nucleon single-particle orbits (LCNO) in a rotating frame by using the coupled-reaction-channel (CRC) theory. Nucleon molecular orbitals and the promotions of nucleon, - especially due to the Landau-Zener radial coupling are discussed with the method above mentioned. (author)

  8. Chern-Simons field theory of two-dimensional electrons in the lowest Landau level

    International Nuclear Information System (INIS)

    Zhang, L.

    1996-01-01

    We propose a fermion Chern-Simons field theory describing two-dimensional electrons in the lowest Landau level. This theory is constructed with a complete set of states, and the lowest-Landau-level constraint is enforced through a δ functional described by an auxiliary field λ. Unlike the field theory constructed directly with the states in the lowest Landau level, this theory allows one, utilizing the physical picture of open-quote open-quote composite fermion,close-quote close-quote to study the fractional quantum Hall states by mapping them onto certain integer quantum Hall states; but, unlike its application in the unconstrained theory, such a mapping is sensible only when interactions between electrons are present. An open-quote open-quote effective mass,close-quote close-quote which characterizes the scale of low energy excitations in the fractional quantum Hall systems, emerges naturally from our theory. We study a Gaussian effective theory and interpret physically the dressed stationary point equation for λ as an equation for the open-quote open-quote mass renormalization close-quote close-quote of composite fermions. copyright 1996 The American Physical Society

  9. Strongly enhanced flow effect from Landau-Vlasov versus Vlasov-Uehling-Uhlenbeck approach

    International Nuclear Information System (INIS)

    Gregoire, C.; Remaud, B.; Sebille, F.; Schuck, P.

    1988-01-01

    The simulation of the collision integral in the Landau-Vlasov approach for heavy ion collisions is examined. It turns out that quantities like the nucleon mean free path can be compared with parallel ensemble models. Convergency of results with time step and sampling is clearly established. Quadratic quantities, like the internal pressure, are found to be strongly underestimated in parallel ensemble models

  10. Approximate solution of generalized Ginzburg-Landau-Higgs system via homotopy perturbation method

    Energy Technology Data Exchange (ETDEWEB)

    Lu Juhong [School of Physics and Electromechanical Engineering, Shaoguan Univ., Guangdong (China); Dept. of Information Engineering, Coll. of Lishui Professional Tech., Zhejiang (China); Zheng Chunlong [School of Physics and Electromechanical Engineering, Shaoguan Univ., Guangdong (China); Shanghai Inst. of Applied Mathematics and Mechanics, Shanghai Univ., SH (China)

    2010-04-15

    Using the homotopy perturbation method, a class of nonlinear generalized Ginzburg-Landau-Higgs systems (GGLH) is considered. Firstly, by introducing a homotopic transformation, the nonlinear problem is changed into a system of linear equations. Secondly, by selecting a suitable initial approximation, the approximate solution with arbitrary degree accuracy to the generalized Ginzburg-Landau-Higgs system is derived. Finally, another type of homotopic transformation to the generalized Ginzburg-Landau-Higgs system reported in previous literature is briefly discussed. (orig.)

  11. Solution Theory of Ginzburg-Landau Theory on BCS-BEC Crossover

    Directory of Open Access Journals (Sweden)

    Shuhong Chen

    2014-01-01

    Full Text Available We establish strong solution theory of time-dependent Ginzburg-Landau (TDGL systems on BCS-BEC crossover. By the properties of Besov, Sobolev spaces, and Fourier functions and the method of bootstrapping argument, we deduce that the global existence of strong solutions to time-dependent Ginzburg-Landau systems on BCS-BEC crossover in various spatial dimensions.

  12. Thermodynamic properties of and Nuclei using modified Ginzburg-Landau theory

    Directory of Open Access Journals (Sweden)

    V Dehghani

    2016-09-01

    Full Text Available In this paper, formulation of Modified Ginsberg – Landau theory of second grade phase transitions has been expressed. Using this theory, termodynamic properties, such as heat capacity, energy, entropy and order parameters ofandnuclei has been investigated. In the heat capacity curve, calculated according to tempreture, a smooth peak is observed which is assumed to be a signature of transition from the paired phase to the normal phase of the nuclei. The same pattern is also observed in the experimental data of the heat capacity of the studied nuclei. Calculations of this model shows that, by increasing tempreture, expectation value of the order parameter tends to zero with smoother slip, comparing with Ginsberg – Landau theory. This indicates  that the pairing effect exists between nucleons even at high temperatures. The experimental data obtained confirms the results of the model qualitatively.

  13. Dynamics of a Landau–Zener non-dissipative system with fluctuating energy levels

    Energy Technology Data Exchange (ETDEWEB)

    Fai, L.C. [Mesoscopic and Multilayer Structures Laboratory, Department of Physics, Faculty of Science, University of Dschang, Dschang (Cameroon); Diffo, J.T., E-mail: diffojaures@yahoo.com [Mesoscopic and Multilayer Structures Laboratory, Department of Physics, Faculty of Science, University of Dschang, Dschang (Cameroon); Department of Physics, Higher Teachers’ Training College, The University of Maroua, Maroua (Cameroon); Ateuafack, M.E.; Tchoffo, M.; Fouokeng, G.C. [Mesoscopic and Multilayer Structures Laboratory, Department of Physics, Faculty of Science, University of Dschang, Dschang (Cameroon)

    2014-12-01

    This paper considers a Landau–Zener (two-level) system influenced by a three-dimensional Gaussian and non-Gaussian coloured noise and finds a general form of the time dependent diabatic quantum bit (qubit) flip transition probabilities in the fast, intermediate and slow noise limits. The qubit flip probability is observed to mimic (for low-frequencies noise) that of the standard LZ problem. The qubit flip probability is also observed to be the measure of quantum coherence of states. The transition probability is observed to be tailored by non-Gaussian low-frequency noise and otherwise by Gaussian low-frequency coloured noise. Intermediate and fast noise limits are observed to alter the memory of the system in time and found to improve and control quantum information processing.

  14. Dynamics of a Landau–Zener non-dissipative system with fluctuating energy levels

    International Nuclear Information System (INIS)

    Fai, L.C.; Diffo, J.T.; Ateuafack, M.E.; Tchoffo, M.; Fouokeng, G.C.

    2014-01-01

    This paper considers a Landau–Zener (two-level) system influenced by a three-dimensional Gaussian and non-Gaussian coloured noise and finds a general form of the time dependent diabatic quantum bit (qubit) flip transition probabilities in the fast, intermediate and slow noise limits. The qubit flip probability is observed to mimic (for low-frequencies noise) that of the standard LZ problem. The qubit flip probability is also observed to be the measure of quantum coherence of states. The transition probability is observed to be tailored by non-Gaussian low-frequency noise and otherwise by Gaussian low-frequency coloured noise. Intermediate and fast noise limits are observed to alter the memory of the system in time and found to improve and control quantum information processing

  15. Landau-Pomeranchuk-Migdal Effect for High-Energy Electrons Observed with Emulsion Chambers

    CERN Document Server

    Yoshida, Kenji; Yanagisawa, K; Kobayashi, T; Sato, Y; Nishimura, J

    We have performed high-energy electron observations using balloon-borne emulsion chambers, and derived the cosmic-ray electron spectrum in the energy range from 30 GeV to 3 TeV. For the calibration of the emulsion chambers, we have also carried out beam tests of 50 GeV, 200 GeV, and 250 GeV electrons at CERN-SPS. The Landau-Pomeranchuk-Migdal (LPM) effect predicts the reduction of amplitude for bremsstrahlung photon emission. It affects to the depth of the first electron-positron pair of the electron-induced shower, the so-called shower starting point. In the emulsion chambers, we can measure the shower starting points for high- energy electrons with the position resolution of 1 m m. From the observations of accelerator-beam electrons of 200 GeV and 250 GeV, and cosmic-ray electrons above 400 GeV, we found the direct evidence of suppression of the bremsstrahlung cross sections due to the LPM effect.

  16. New Wang-Landau approach to obtain phase diagrams for multicomponent alloys

    Science.gov (United States)

    Takeuchi, Kazuhito; Tanaka, Ryohei; Yuge, Koretaka

    2017-10-01

    We develop an approach to apply the Wang-Landau algorithm to multicomponent alloys in a semi-grand-canonical ensemble. Although the Wang-Landau algorithm has great advantages over conventional sampling methods, there are few applications to alloys. This is because calculating compositions in a semi-grand-canonical ensemble via the Wang-Landau algorithm requires a multidimensional density of states in terms of total energy and compositions, and constructing it is difficult from the viewpoints of both implementation and computational cost. In this study, we develop a simple approach to calculate the alloy phase diagram based on the Wang-Landau algorithm, and show that a number of one-dimensional densities of states could lead to compositions in a semi-grand-canonical ensemble as a multidimensional density of states could. Finally, we apply the present method to Cu-Au and Pd-Rh alloys and confirm that the present method successfully describes the phase diagram with high efficiency, validity, and accuracy.

  17. Avoidance of a Landau pole by flat contributions in QED

    Energy Technology Data Exchange (ETDEWEB)

    Klaczynski, Lutz, E-mail: lutz.klaczynski@gmx.de [Department of Physics, Humboldt University Berlin, 12489 Berlin (Germany); Kreimer, Dirk, E-mail: kreimer@mathematik.hu-berlin.de [Alexander von Humboldt Chair in Mathematical Physics, Humboldt University, Berlin 12489 (Germany)

    2014-05-15

    We consider massless Quantum Electrodynamics in the momentum scheme and carry forward an approach based on Dyson–Schwinger equations to approximate both the β-function and the renormalized photon self-energy (Yeats, 2011). Starting from the Callan–Symanzik equation, we derive a renormalization group (RG) recursion identity which implies a non-linear ODE for the anomalous dimension and extract a sufficient but not necessary criterion for the existence of a Landau pole. This criterion implies a necessary condition for QED to have no such pole. Solving the differential equation exactly for a toy model case, we integrate the corresponding RG equation for the running coupling and find that even though the β-function entails a Landau pole it exhibits a flat contribution capable of decreasing its growth, in other cases possibly to the extent that such a pole is avoided altogether. Finally, by applying the recursion identity, we compute the photon propagator and investigate the effect of flat contributions on both spacelike and timelike photons. -- Highlights: •We present an approach to approximate both the β-function and the photon self-energy. •We find a sufficient criterion for the self-energy to entail the existence of a Landau pole. •We study non-perturbative ‘flat’ contributions that emerge within the context of our approach. •We discuss a toy model and how it is affected by flat contributions.

  18. Non perturbative analysis of an N=2 Landau-Ginsburg model

    International Nuclear Information System (INIS)

    Leaf Herrmann, W.A.

    1993-01-01

    We analyze the topological sector of an N=2 Landau-Ginsburg model using nonperturbative methods. In particular, we study the renormalization group flow between two superconformal minimal models, numerically compute the correlation functions along this trajectory, and compare the results to semi-classical calculations. We also study some aspects of arbitrary supersymmetric perturbations of the Landau-Ginsburg model. 20 refs, 4 figs

  19. Zero-field magnetic response functions in Landau levels

    Science.gov (United States)

    Gao, Yang; Niu, Qian

    2017-07-01

    We present a fresh perspective on the Landau level quantization rule; that is, by successively including zero-field magnetic response functions at zero temperature, such as zero-field magnetization and susceptibility, the Onsager’s rule can be corrected order by order. Such a perspective is further reinterpreted as a quantization of the semiclassical electron density in solids. Our theory not only reproduces Onsager’s rule at zeroth order and the Berry phase and magnetic moment correction at first order but also explains the nature of higher-order corrections in a universal way. In applications, those higher-order corrections are expected to curve the linear relation between the level index and the inverse of the magnetic field, as already observed in experiments. Our theory then provides a way to extract the correct value of Berry phase as well as the magnetic susceptibility at zero temperature from Landau level fan diagrams in experiments. Moreover, it can be used theoretically to calculate Landau levels up to second-order accuracy for realistic models.

  20. Generalized Landau-Lifshitz models on the interval

    International Nuclear Information System (INIS)

    Doikou, Anastasia; Karaiskos, Nikos

    2011-01-01

    We study the classical generalized gl n Landau-Lifshitz (L-L) model with special boundary conditions that preserve integrability. We explicitly derive the first non-trivial local integral of motion, which corresponds to the boundary Hamiltonian for the sl 2 L-L model. Novel expressions of the modified Lax pairs associated to the integrals of motion are also extracted. The relevant equations of motion with the corresponding boundary conditions are determined. Dynamical integrable boundary conditions are also examined within this spirit. Then the generalized isotropic and anisotropic gl n Landau-Lifshitz models are considered, and novel expressions of the boundary Hamiltonians and the relevant equations of motion and boundary conditions are derived.

  1. Inertia and ion Landau damping of low-frequency magnetohydrodynamical modes in tokamaks

    International Nuclear Information System (INIS)

    Bondeson, A.; Chu, M.S.

    1996-01-01

    The inertia and Landau damping of low-frequency magnetohydrodynamical modes are investigated using the drift-kinetic energy principle for the motion along the magnetic field. Toroidal trapping of the ions decreases the Landau damping and increases the inertia for frequencies below (r/R) 1/2 v thi /qR. The theory is applied to toroidicity-induced Alfvacute en eigenmodes and to resistive wall modes in rotating plasmas. An explanation of the beta-induced Alfvacute en eigenmode is given in terms of the Pfirsch endash Schlueter-like enhancement of inertia at low frequency. The toroidal inertia enhancement also increases the effects of plasma rotation on resistive wall modes. copyright 1996 American Institute of Physics

  2. Coherence in Magnetic Quantum Tunneling

    Science.gov (United States)

    Fernandez, Julio F.

    2001-03-01

    Crystals of single molecule magnets such as Mn_12 and Fe8 behave at low temperatures as a collection of independent spins. Magnetic anisotropy barriers slow down spin-flip processes. Their rate Γ becomes temperature independent at sufficiently low temperature. Quantum tunneling (QT) accounts for this behavior. Currently, spin QT in Mn_12 and Fe8 is assumed to proceed as an incoherent sum of small probability increments that occur whenever a bias field h(t) (arising from hyperfine interactions with nuclear spins) that varies with time t becomes sufficiently small, as in Landau-Zener transitions. Within a two-state model, we study the behavior of a suitably defined coherence time τ_φ and compare it with the correlation time τh for h(t). It turns out that τ_φ >τ_h, when τ_hδ h < hbar, where δ h is the rms deviation of h. We show what effect such coherence has on Γ. Its dependence on a static longitudinal applied field Hz is drastically affected. There is however no effect if the field is swept through resonance.

  3. Propuesta de un método de ordenador para resolver el ajuste a la ecuación de Zener-Hollomon (Garofalo

    Directory of Open Access Journals (Sweden)

    Rieiro, I.

    1996-10-01

    Full Text Available An integrated computational method to solve the Zener-Hollomon equation has been developed by the authors. This method solves the fitting problem of the equation of Zener-Hollomon for wide ranges of applied stress, strain rate and work temperature by means of the progressive application of three kinds of algorithms. In the first place a program, by means of a reiterated linear regression by planes, allows to get some values that will be later the initial values of a second block of algorithms. It permits also to purify the experimental data set. The second block of algorithms carries out a fitting by nonlinear least squares using a variation of the modified Gauss-Newton method. In the third place a group of programs is chained that permit iterate starting by the solution of the previous program approaching (if it is necessary line by line in R2 until the optimum value is reached. All this with a support of statistical analysis for they determine the accuracy of each step, of the data, of the residuals and of the last fitting reached.

    Se presenta un método de ordenador integrado, desarrollado por los autores, para resolver la ecuación de Zener-Hollomon. Este método resuelve el problema del ajuste de la ecuación de Zener-Hollomon para amplios rangos de tensión aplicada, velocidad de deformación y temperatura de trabajo, mediante la aplicación progresiva de tres tipos de algoritmos. En primer lugar, una regresión reiterada multivariante por planos, para obtener unos valores que serán considerados como iniciales para un segundo bloque de algoritmos, además de depurar la base experimental de datos. El segundo bloque de algoritmos realiza un ajuste por mínimos cuadrados no lineales usando una modificación del método de Gauss-Newton modificado. En tercer lugar se encadena un grupo de programas que permiten iterar a partir de la solución del programa no lineal acercándose (si es preciso por líneas en R2

  4. Thirty years of the Landau Institute selected papers

    CERN Document Server

    Khalatnikov, I M

    1996-01-01

    The Landau Institute for Theoretical Physics was created in 1965 by a group of LD Landau's pupils. Very soon, it was widely recognized as one of the world's leading centers in theoretical physics. According to Science Magazine, the Institute in the eighties had the highest citation index among all the scientific organizations in the former Soviet Union. This collection of the best papers of the Institute reflects the development of the many directions in the exact sciences during the last 30 years. The reader can find the original formulations of well-known notions in condensed matter theory,

  5. Landau Damping of the Weak Head-Tail Instability at Tevatron

    CERN Document Server

    Ivanov, Petr M; Annala, Jerry; Lebedev, Valeri; Shiltsev, Vladimir

    2005-01-01

    Landau damping of the head-tail modes in Tevatron beam with the help of octupole-generated betatron tune spreads permits to reduce chromaticity from 15-20 units to zero thus significantly improving the beam lifetime. The octupole strengths have been experimentally optimized at different stages of the Tevatron operation, from proton injection to collision. Predictions of the analytical Landau damping model are compared with the experimental results.

  6. Breakdown of Zero-Energy Quantum Hall State in Graphene in the Light of Current Fluctuations and Shot Noise

    Science.gov (United States)

    Laitinen, Antti; Kumar, Manohar; Elo, Teemu; Liu, Ying; Abhilash, T. S.; Hakonen, Pertti J.

    2018-06-01

    We have investigated the cross-over from Zener tunneling of single charge carriers to avalanche type of bunched electron transport in a suspended graphene Corbino disk in the zeroth Landau level. At low bias, we find a tunneling current that follows the gyrotropic Zener tunneling behavior. At larger bias, we find an avalanche type of transport that sets in at a smaller current the larger the magnetic field is. The low-frequency noise indicates strong bunching of the electrons in the avalanches. On the basis of the measured low-frequency switching noise power, we deduce the characteristic switching rates of the avalanche sequence. The simultaneous microwave shot noise measurement also reveals intrinsic correlations within the avalanche pulses and indicate a decrease in correlations with increasing bias.

  7. Fractional charge and inter-Landau-level states at points of singular curvature.

    Science.gov (United States)

    Biswas, Rudro R; Son, Dam Thanh

    2016-08-02

    The quest for universal properties of topological phases is fundamentally important because these signatures are robust to variations in system-specific details. Aspects of the response of quantum Hall states to smooth spatial curvature are well-studied, but challenging to observe experimentally. Here we go beyond this prevailing paradigm and obtain general results for the response of quantum Hall states to points of singular curvature in real space; such points may be readily experimentally actualized. We find, using continuum analytical methods, that the point of curvature binds an excess fractional charge and sequences of quantum states split away, energetically, from the degenerate bulk Landau levels. Importantly, these inter-Landau-level states are bound to the topological singularity and have energies that are universal functions of bulk parameters and the curvature. Our exact diagonalization of lattice tight-binding models on closed manifolds demonstrates that these results continue to hold even when lattice effects are significant. An important technological implication of these results is that these inter-Landau-level states, being both energetically and spatially isolated quantum states, are promising candidates for constructing qubits for quantum computation.

  8. Fractional generalization of the Ginzburg–Landau equation: an unconventional approach to critical phenomena in complex media

    DEFF Research Database (Denmark)

    Milovanov, A.V.; Juul Rasmussen, J.

    2005-01-01

    Equations built on fractional derivatives prove to be a powerful tool in the description of complex systems when the effects of singularity, fractal supports, and long-range dependence play a role. In this Letter, we advocate an application of the fractional derivative formalism to a fairly general...... class of critical phenomena when the organization of the system near the phase transition point is influenced by a competing nonlocal ordering. Fractional modifications of the free energy functional at criticality and of the widely known Ginzburg-Landau equation central to the classical Landau theory...... of second-type phase transitions are discussed in some detail. An implication of the fractional Ginzburg-Landau equation is a renormalization of the transition temperature owing to the nonlocality present. (c) 2005 Elsevier B.V. All rights reserved....

  9. Landau singularities and symbology: one- and two-loop MHV amplitudes in SYM theory

    Energy Technology Data Exchange (ETDEWEB)

    Dennen, Tristan; Spradlin, Marcus; Volovich, Anastasia [Department of Physics, Brown University,Providence RI 02912 (United States)

    2016-03-14

    We apply the Landau equations, whose solutions parameterize the locus of possible branch points, to the one- and two-loop Feynman integrals relevant to MHV amplitudes in planar N=4 super-Yang-Mills theory. We then identify which of the Landau singularities appear in the symbols of the amplitudes, and which do not. We observe that all of the symbol entries in the two-loop MHV amplitudes are already present as Landau singularities of one-loop pentagon integrals.

  10. Landau singularities and symbology: one- and two-loop MHV amplitudes in SYM theory

    International Nuclear Information System (INIS)

    Dennen, Tristan; Spradlin, Marcus; Volovich, Anastasia

    2016-01-01

    We apply the Landau equations, whose solutions parameterize the locus of possible branch points, to the one- and two-loop Feynman integrals relevant to MHV amplitudes in planar N=4 super-Yang-Mills theory. We then identify which of the Landau singularities appear in the symbols of the amplitudes, and which do not. We observe that all of the symbol entries in the two-loop MHV amplitudes are already present as Landau singularities of one-loop pentagon integrals.

  11. Landau-Ginzburg Orbifolds, Mirror Symmetry and the Elliptic Genus

    OpenAIRE

    Berglund, P.; Henningson, M.

    1994-01-01

    We compute the elliptic genus for arbitrary two dimensional $N=2$ Landau-Ginzburg orbifolds. This is used to search for possible mirror pairs of such models. We show that if two Landau-Ginzburg models are conjugate to each other in a certain sense, then to every orbifold of the first theory corresponds an orbifold of the second theory with the same elliptic genus (up to a sign) and with the roles of the chiral and anti-chiral rings interchanged. These orbifolds thus constitute a possible mirr...

  12. Quenching points of dimeric single-molecule magnets: Exchange interaction effects

    International Nuclear Information System (INIS)

    Florez, J.M.; Nunez, Alvaro S.; Vargas, P.

    2010-01-01

    We study the quenched energy-splitting (Δ E ) of a single-molecule magnet (SMM) conformed by two exchange coupled giant-spins. An assessment of two nontrivial characteristics of this quenching is presented: (i) The quenching-points of a strongly exchange-coupled dimer differ from the ones of their respective giant-spin modeled SMM and such a difference can be well described by using the Solari-Kochetov extra phase; (ii) the dependence on the exchange coupling of the magnetic field values at the quenching-points when Δ E passes from monomeric to dimeric behavior. The physics behind these exchange-modified points, their relation with the Δ E -oscillations experimentally obtained by the Landau-Zener method and with the diabolical-plane of a SMM, is discussed.

  13. Quenching points of dimeric single-molecule magnets: Exchange interaction effects

    Energy Technology Data Exchange (ETDEWEB)

    Florez, J.M., E-mail: juanmanuel.florez@alumnos.usm.c [Departamento de Fisica, Universidad Tecnica Federico Santa Maria, P.O. Box 110-V, Valparaiso (Chile); Nunez, Alvaro S., E-mail: alnunez@dfi.uchile.c [Departamento de Fisica, Facultad de Ciencias Fisicas y Matematicas, Universidad de Chile, Casilla 487-3, Santiago (Chile); Vargas, P., E-mail: patricio.vargas@usm.c [Departamento de Fisica, Universidad Tecnica Federico Santa Maria, P.O. Box 110-V, Valparaiso (Chile)

    2010-11-15

    We study the quenched energy-splitting ({Delta}{sub E}) of a single-molecule magnet (SMM) conformed by two exchange coupled giant-spins. An assessment of two nontrivial characteristics of this quenching is presented: (i) The quenching-points of a strongly exchange-coupled dimer differ from the ones of their respective giant-spin modeled SMM and such a difference can be well described by using the Solari-Kochetov extra phase; (ii) the dependence on the exchange coupling of the magnetic field values at the quenching-points when {Delta}{sub E} passes from monomeric to dimeric behavior. The physics behind these exchange-modified points, their relation with the {Delta}{sub E}-oscillations experimentally obtained by the Landau-Zener method and with the diabolical-plane of a SMM, is discussed.

  14. Numerical Analysis of Ginzburg-Landau Models for Superconductivity.

    Science.gov (United States)

    Coskun, Erhan

    Thin film conventional, as well as High T _{c} superconductors of various geometric shapes placed under both uniform and variable strength magnetic field are studied using the universially accepted macroscopic Ginzburg-Landau model. A series of new theoretical results concerning the properties of solution is presented using the semi -discrete time-dependent Ginzburg-Landau equations, staggered grid setup and natural boundary conditions. Efficient serial algorithms including a novel adaptive algorithm is developed and successfully implemented for solving the governing highly nonlinear parabolic system of equations. Refinement technique used in the adaptive algorithm is based on modified forward Euler method which was also developed by us to ease the restriction on time step size for stability considerations. Stability and convergence properties of forward and modified forward Euler schemes are studied. Numerical simulations of various recent physical experiments of technological importance such as vortes motion and pinning are performed. The numerical code for solving time-dependent Ginzburg-Landau equations is parallelized using BlockComm -Chameleon and PCN. The parallel code was run on the distributed memory multiprocessors intel iPSC/860, IBM-SP1 and cluster of Sun Sparc workstations, all located at Mathematics and Computer Science Division, Argonne National Laboratory.

  15. Critical Landau Velocity in Helium Nanodroplets

    NARCIS (Netherlands)

    Brauer, N.B.; Smolarek, S.; Loginov, E.; Mateo, D.; Hernando, A.; Pi, M.; Barranco, M.; Buma, W.J.; Drabbels, M.

    2013-01-01

    The best-known property of superfluid helium is the vanishing viscosity that objects experience while moving through the liquid with speeds below the so-called critical Landau velocity. This critical velocity is generally considered a macroscopic property as it is related to the collective

  16. Observation of roton density of states in two-dimensional Landau-level excitations

    International Nuclear Information System (INIS)

    Pinczuk, A.; Valladares, J.P.; Heiman, D.; Gossard, A.C.; English, J.H.; Tu, C.W.; Pfeiffer, L.; West, K.

    1988-01-01

    Inelastic light scattering by inter-Landau-level excitations of the 2D electron gas in high-mobility GaAs structures in a perpendicular magnetic field was observed at the energies of the critical points in the mode dispersions. For Landau-level filling factors /nu//ge/, structure in the spectra indicates the excitonic binding and roton behavior predicted by the Hartree-Fock approximation. The large critical-point wave vectors, qapprox. >((h/2/pi/)c/eB)/sup -1/2/approx. >10/sup 6/ cm/sup -1/, are probably accessible in resonant light scattering through the residual disorder that broadens the Landau levels

  17. Frequency dependence of complex moduli of brain tissue using a fractional Zener model

    International Nuclear Information System (INIS)

    Kohandel, M; Sivaloganathan, S; Tenti, G; Darvish, K

    2005-01-01

    Brain tissue exhibits viscoelastic behaviour. If loading times are substantially short, static tests are not sufficient to determine the complete viscoelastic behaviour of the material, and dynamic test methods are more appropriate. The concept of complex modulus of elasticity is a powerful tool for characterizing the frequency domain behaviour of viscoelastic materials. On the other hand, it is well known that classical viscoelastic models can be generalized by means of fractional calculus to describe more complex viscoelastic behaviour of materials. In this paper, the fractional Zener model is investigated in order to describe the dynamic behaviour of brain tissue. The model is fitted to experimental data of oscillatory shear tests of bovine brain tissue to verify its behaviour and to obtain the material parameters

  18. Effects of Gogny type interactions on the nuclear flow

    International Nuclear Information System (INIS)

    Sebille, F.; De La Mota, V.; Jouault, B.; Schuck, P.

    1995-01-01

    A flow analysis on symmetric and asymmetric reactions from 100 to 400 MeV/n is performed in the framework of the semi-classical Landau-Vlasov approach. In this energy range our results present two different trends. At lower energies it is governed by the momentum dependence of the nuclear optical potential, whereas at higher energies its density dependence plays a crucial role leading to a rather pronounced sensitivity of the incompressibility modulus. The non-locality of the nuclear interaction is relevant for asymmetric colliding systems. With an incompressibility modulus in the vicinity of 200 MeV, an excellent quantitative description of the flow behavior with incident energy and impact parameter or the system mass is provided. (authors)., 26 refs., 6 figs., 3 tabs

  19. The Interplay of Rashba Spin-Orbit Interaction and Landau Level Broadening on a Two-Dimensional Electron Gas Under a Tilted Magnetic Field

    International Nuclear Information System (INIS)

    Gammag, Rayda; Villagonzalo, Cristine

    2012-01-01

    A two-dimensional electron gas in a tilted magnetic field with Rashba spin-orbit interaction (RSOI) was studied. The RSOI is accredited to the asymmetry of the heterostructure where the two-dimensional electron gas is found. The effects of the disorder-attributed Landau level broadening and the RSOI on the spin splitting were identified by simulating the density of states which was assumed to take a Gaussian shape. Increased Landau level broadening obscures the spin splitting and increases the overlap between spin states resulting to stout Gaussian peaks. On the other hand, stronger RSOI amplifies the splitting and lessens the overlap between spin states of the Landau levels. The splitting, however, results to stouter peaks. The similarity in the RSOI and Landau level broadening effects can be explained by recognizing that the asymmetry of the heterostructure is in itself a form of structural disorder.

  20. Theoretical studies in nuclear physics. Three year progress report and final report

    International Nuclear Information System (INIS)

    Landau, R.H.; Madsen, V.A.

    1996-01-01

    In 1995 the DOE grant in Nuclear theory with Professors Rubin H. Landau and Victor A. Madsen as co-principal investigators ended. Their research was carried out in collaboration with graduate students in Corvallis, and with scientists at LLNL-Livermore, Los Alamos, TRIUMF, KFA-Julich, Hamburg University, Melbourne University, The Thinking Machine Corporation and IBM Research. Activities in nuclear and particle physics at Oregon State University (OSU) were diverse and active. Madsen's work concentrated on the relation of reactions to the nuclear structure, and Landau's work concentrated on intermediate energy physics, few-body problems, and computational physics. The Landau group had a weekly meeting of students and visitors. There was a weekly nuclear seminar with experimental and theoretical colleagues, and a weekly departmental colloquium. The DOE support had permitted the group to run Unix workstations networked to other computers in the Physics Department and the University. Since 1990 OSU has been using IBM RISC System 6000/model 530 with console and four X-stations. The equipment was purchased and is maintained with yearly DOE funding of the group

  1. Laser-induced charge transfer in the HeH2+ quasimolecule

    International Nuclear Information System (INIS)

    Errea, L.F.; Mendez, L.; Riera, A.

    1983-01-01

    In a recent publication, the charge transfer cross section for He 2+ +H(ls) collisions through photon-assisted 2psigma--3dsigma transitions was calculated; this calculation, however, contained several errors whose quantitative--even qualitative effect on the results is not obvious. We present a correct evaluation of this laser-induced cross section, which turns out to be larger, and present a maximum for longer wavelengths, than the values previously reported. In addition, we have checked the applicability of perturbation theory, of the stationary phase, uniform and Landau--Zener approximations, and the importance of potentially competitive photon-assisted reactions

  2. Laser-induced charge transfer in the HeH/sup 2 +/ quasimolecule

    Energy Technology Data Exchange (ETDEWEB)

    Errea, L.F.; Mendez, L.; Riera, A.

    1983-11-01

    In a recent publication, the charge transfer cross section for He/sup 2 +/+H(ls) collisions through photon-assisted 2psigma--3dsigma transitions was calculated; this calculation, however, contained several errors whose quantitative--even qualitative effect on the results is not obvious. We present a correct evaluation of this laser-induced cross section, which turns out to be larger, and present a maximum for longer wavelengths, than the values previously reported. In addition, we have checked the applicability of perturbation theory, of the stationary phase, uniform and Landau--Zener approximations, and the importance of potentially competitive photon-assisted reactions.

  3. Spin Singlet Quantum Hall Effect and nonabelian Landau-Ginzburg theory

    International Nuclear Information System (INIS)

    Balatsky, A.

    1991-01-01

    In this paper we present a theory of Singlet Quantum Hall Effect (SQHE). We show that the Halperin-Haldane SQHE wave function can be written in the form of a product of a wave function for charged semions in a magnetic field and a wave function for the Chiral Spin Liquid of neutral spin-1/2 semions. We introduce field-theoretic model in which the electron operators are factorized in terms of charged spinless semions (holons) and neutral spin-1/2 semions (spinons). Broken time reversal symmetry and short ranged spin correlations lead to Su(2) κ=1 Chern-Simons term in Landau-Ginzburg action for SQHE phase. We construct appropriate coherent states for SQHE phase and show the existence of SU(2) valued gauge potential. This potential appears as a result of ''spin rigidity'' of the ground state against any displacements of nodes of wave function from positions of the particles and reflects the nontrivial monodromy in the presence of these displacenmants. We argue that topological structure of Su(2) κ=1 Chern-Simons theory unambiguously dictates semion statistics of spinons. 19 refs

  4. The Landau-Lifshitz equation of the ferromagnetic spin chain and harmonic maps

    International Nuclear Information System (INIS)

    Guo Boling; Hong Minchun.

    1992-05-01

    We prove a global existence of solutions for the Landau-Lifshitz equation of the ferromagnetic spin chain from an m-dimensional manifold M into the unit sphere S 2 of R 3 and establish some new links between harmonic maps and the solutions of the Landau-Lifshitz equation. (author). 25 refs

  5. Relativistic Landau levels in the rotating cosmic string spacetime

    Energy Technology Data Exchange (ETDEWEB)

    Cunha, M.S. [Universidade Estadual do Ceara, Grupo de Fisica Teorica (GFT), Fortaleza, CE (Brazil); Muniz, C.R. [Universidade Estadual do Ceara, Faculdade de Educacao, Ciencias e Letras de Iguatu, Iguatu, CE (Brazil); Christiansen, H.R. [Instituto Federal de Ciencia, Educacao e Tecnologia, IFCE Departamento de Fisica, Sobral (Brazil); Bezerra, V.B. [Universidade Federal da Paraiba-UFPB, Departamento de Fisica, Caixa Postal 5008, Joao Pessoa, PB (Brazil)

    2016-09-15

    In the spacetime induced by a rotating cosmic string we compute the energy levels of a massive spinless particle coupled covariantly to a homogeneous magnetic field parallel to the string. Afterwards, we consider the addition of a scalar potential with a Coulomb-type and a linear confining term and completely solve the Klein-Gordon equations for each configuration. Finally, assuming rigid-wall boundary conditions, we find the Landau levels when the linear defect is itself magnetized. Remarkably, our analysis reveals that the Landau quantization occurs even in the absence of gauge fields provided the string is endowed with spin. (orig.)

  6. Quantum Hall conductivity in a Landau type model with a realistic geometry

    International Nuclear Information System (INIS)

    Chandelier, F.; Georgelin, Y.; Masson, T.; Wallet, J.-C.

    2003-01-01

    In this paper, we revisit some quantum mechanical aspects related to the quantum Hall effect. We consider a Landau type model, paying a special attention to the experimental and geometrical features of quantum Hall experiments. The resulting formalism is then used to compute explicitly the Hall conductivity from a Kubo formula

  7. Periods for Calabi-Yau and Landau-Ginzburg vacua

    CERN Document Server

    Berglund, P; De la Ossa, X C; Font, A; Hübsch, T; Jancic, D; Quevedo, Fernando; Berglund, Per; Candelas, Philip; Ossa, Xenia de la; Font, Anamaria; Hubsch, Tristan; Jancic, Dubravka; Quevedo, Fernando

    1994-01-01

    The complete structure of the moduli space of \\cys\\ and the associated Landau-Ginzburg theories, and hence also of the corresponding low-energy effective theory that results from (2,2) superstring compactification, may be determined in terms of certain holomorphic functions called periods. These periods are shown to be readily calculable for a great many such models. We illustrate this by computing the periods explicitly for a number of classes of \\cys. We also point out that it is possible to read off from the periods certain important information relating to the mirror manifolds.

  8. Real-time relaxation and kinetics in hot scalar QED: Landau damping

    International Nuclear Information System (INIS)

    Boyanovsky, D.; Vega, H.J. de; Holman, R.; Kumar, S.P.; Pisarski, R.D.

    1998-01-01

    The real time evolution of non-equilibrium expectation values with soft length scales ∼k -1 >(eT) -1 is solved in hot scalar electrodynamics, with a view towards understanding relaxational phenomena in the QGP and the electroweak plasma. We find that the gauge invariant non-equilibrium expectation values relax via power laws to asymptotic amplitudes that are determined by the quasiparticle poles. The long time relaxational dynamics and relevant time scales are determined by the behavior of the retarded self-energy not at the small frequencies, but at the Landau damping thresholds. This explains the presence of power laws and not of exponential decay. In the process we rederive the HTL effective action using non-equilibrium field theory. Furthermore we obtain the influence functional, the Langevin equation and the fluctuation-dissipation theorem for the soft modes, identifying the correlators that emerge in the classical limit. We show that a Markovian approximation fails to describe the dynamics both at short and long times. We find that the distribution function for soft quasiparticles relaxes with a power law through Landau damping. We also introduce a novel kinetic approach that goes beyond the standard Boltzmann equation by incorporating off-shell processes and find that the distribution function for soft quasiparticles relaxes with a power law through Landau damping. We find an unusual dressing dynamics of bare particles and anomalous (logarithmic) relaxation of hard quasiparticles. copyright 1998 The American Physical Society

  9. The Wang-Landau Sampling Algorithm

    Science.gov (United States)

    Landau, David P.

    2003-03-01

    Over the past several decades Monte Carlo simulations[1] have evolved into a powerful tool for the study of wide-ranging problems in statistical/condensed matter physics. Standard methods sample the probability distribution for the states of the system, usually in the canonical ensemble, and enormous improvements have been made in performance through the implementation of novel algorithms. Nonetheless, difficulties arise near phase transitions, either due to critical slowing down near 2nd order transitions or to metastability near 1st order transitions, thus limiting the applicability of the method. We shall describe a new and different Monte Carlo approach [2] that uses a random walk in energy space to determine the density of states directly. Once the density of states is estimated, all thermodynamic properties can be calculated at all temperatures. This approach can be extended to multi-dimensional parameter spaces and has already found use in classical models of interacting particles including systems with complex energy landscapes, e.g., spin glasses, protein folding models, etc., as well as for quantum models. 1. A Guide to Monte Carlo Simulations in Statistical Physics, D. P. Landau and K. Binder (Cambridge U. Press, Cambridge, 2000). 2. Fugao Wang and D. P. Landau, Phys. Rev. Lett. 86, 2050 (2001); Phys. Rev. E64, 056101-1 (2001).

  10. Infrared spectroscopy of Landau levels of graphene.

    Science.gov (United States)

    Jiang, Z; Henriksen, E A; Tung, L C; Wang, Y-J; Schwartz, M E; Han, M Y; Kim, P; Stormer, H L

    2007-05-11

    We report infrared studies of the Landau level (LL) transitions in single layer graphene. Our specimens are density tunable and show in situ half-integer quantum Hall plateaus. Infrared transmission is measured in magnetic fields up to B=18 T at selected LL fillings. Resonances between hole LLs and electron LLs, as well as resonances between hole and electron LLs, are resolved. Their transition energies are proportional to sqrt[B], and the deduced band velocity is (-)c approximately equal to 1.1 x 10(6) m/s. The lack of precise scaling between different LL transitions indicates considerable contributions of many-particle effects to the infrared transition energies.

  11. Landau - Great scientist and teacher

    International Nuclear Information System (INIS)

    1968-01-01

    In 1962 a feeling of deep sadness was experienced by the whole scientific world when it was learned that L.D. Landau, one of the most distinguished physicists and teachers of the USSR, has been seriously injured in a road accident. All the resources of his own country and ready assistance from many others combined to save his life, but early this year the long fight to recover his faculties ended with his death. (author)

  12. The Landau-Placzek ratio for multicomponent fluids

    NARCIS (Netherlands)

    Lekkerkerker, H.N.W.; Laidlaw, W.G.

    1972-01-01

    Under the assumption that the coupling between the sound modes and modes associated with heat and mass diffusion can be neglected, an expression for the Landau-Placzek ratio for multicomponent fluids is derived using thermodynamic fluctuation theory. Applications of the general formula to ternary

  13. Symmetry of Uniaxial Global Landau--de Gennes Minimizers in the Theory of Nematic Liquid Crystals

    KAUST Repository

    Henao, Duvan; Majumdar, Apala

    2012-01-01

    We extend the recent radial symmetry results by Pisante [J. Funct. Anal., 260 (2011), pp. 892-905] and Millot and Pisante [J. Eur. Math. Soc. (JEMS), 12 (2010), pp. 1069- 1096] (who show that the equivariant solutions are the only entire solutions of the three-dimensional Ginzburg-Landau equations in superconductivity theory) to the Landau-de Gennes framework in the theory of nematic liquid crystals. In the low temperature limit, we obtain a characterization of global Landau-de Gennes minimizers, in the restricted class of uniaxial tensors, in terms of the well-known radial-hedgehog solution. We use this characterization to prove that global Landau-de Gennes minimizers cannot be purely uniaxial for sufficiently low temperatures. Copyright © by SIAM.

  14. Effect of Noise on the Decoherence of a Central Electron Spin Coupled to an Antiferromagnetic Spin Bath

    Directory of Open Access Journals (Sweden)

    G. C. Fouokeng

    2014-01-01

    Full Text Available We analyze the influence of a two-state autocorrelated noise on the decoherence and on the tunneling Landau-Zener (LZ transitions during a two-level crossing of a central electron spin (CES coupled to a one dimensional anisotropic-antiferomagnetic spin, driven by a time-dependent global external magnetic field. The energy splitting of the coupled spin system is found through an approach that computes the noise-averaged frequency. At low magnetic field intensity, the decoherence (or entangled state of a coupled spin system is dominated by the noise intensity. The effects of the magnetic field pulse and the spin gap antiferromagnetic material used suggest to us that they may be used as tools for the direct observation of the tunneling splitting through the LZ transitions in the sudden limit. We found that the dynamical frequencies display basin-like behavior decay with time, with the birth of entanglement, while the LZ transition probability shows Gaussian shape.

  15. Landau damping in trapped Bose condensed gases

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, B; Zaremba, E [Department of Physics, Queen' s University, Kingston, ON K7L 3N6 (Canada)

    2003-07-01

    We study Landau damping in dilute Bose-Einstein condensed gases in both spherical and prolate ellipsoidal harmonic traps. We solve the Bogoliubov equations for the mode spectrum in both of these cases, and calculate the damping by summing over transitions between excited quasiparticle states. The results for the spherical case are compared to those obtained in the Hartree-Fock (HF) approximation, where the excitations take on a single-particle character, and excellent agreement between the two approaches is found. We have also taken the semiclassical limit of the HF approximation and obtain a novel expression for the Landau damping rate involving the time-dependent self-diffusion function of the thermal cloud. As a final approach, we study the decay of a condensate mode by making use of dynamical simulations in which both the condensate and thermal cloud are evolved explicitly as a function of time. A detailed comparison of all these methods over a wide range of sample sizes and trap geometries is presented.

  16. A fast non-Fourier method for Landau-fluid operators

    Energy Technology Data Exchange (ETDEWEB)

    Dimits, A. M., E-mail: dimits1@llnl.gov; Joseph, I.; Umansky, M. V. [Lawrence Livermore National Laboratory, L-637, P.O. Box 808, Livermore, California 94511-0808 (United States)

    2014-05-15

    An efficient and versatile non-Fourier method for the computation of Landau-fluid (LF) closure operators [Hammett and Perkins, Phys. Rev. Lett. 64, 3019 (1990)] is presented, based on an approximation by a sum of modified-Helmholtz-equation solves (SMHS) in configuration space. This method can yield fast-Fourier-like scaling of the computational time requirements and also provides a very compact data representation of these operators, even for plasmas with large spatial nonuniformity. As a result, the method can give significant savings compared with direct application of “delocalization kernels” [e.g., Schurtz et al., Phys. Plasmas 7, 4238 (2000)], both in terms of computational cost and memory requirements. The method is of interest for the implementation of Landau-fluid models in situations where the spatial nonuniformity, particular geometry, or boundary conditions render a Fourier implementation difficult or impossible. Systematic procedures have been developed to optimize the resulting operators for accuracy and computational cost. The four-moment Landau-fluid model of Hammett and Perkins has been implemented in the BOUT++ code using the SMHS method for LF closure. Excellent agreement has been obtained for the one-dimensional plasma density response function between driven initial-value calculations using this BOUT++ implementation and matrix eigenvalue calculations using both Fourier and SMHS non-Fourier implementations of the LF closures. The SMHS method also forms the basis for the implementation, which has been carried out in the BOUT++ code, of the parallel and toroidal drift-resonance LF closures. The method is a key enabling tool for the extension of gyro-Landau-fluid models [e.g., Beer and Hammett, Phys. Plasmas 3, 4046 (1996)] to codes that treat regions with strong profile variation, such as the tokamak edge and scrapeoff-layer.

  17. A large class of solvable multistate Landau–Zener models and quantum integrability

    Science.gov (United States)

    Chernyak, Vladimir Y.; Sinitsyn, Nikolai A.; Sun, Chen

    2018-06-01

    The concept of quantum integrability has been introduced recently for quantum systems with explicitly time-dependent Hamiltonians (Sinitsyn et al 2018 Phys. Rev. Lett. 120 190402). Within the multistate Landau–Zener (MLZ) theory, however, there has been a successful alternative approach to identify and solve complex time-dependent models (Sinitsyn and Chernyak 2017 J. Phys. A: Math. Theor. 50 255203). Here we compare both methods by applying them to a new class of exactly solvable MLZ models. This class contains systems with an arbitrary number of interacting states and shows quick growth with N number of exact adiabatic energy crossing points, which appear at different moments of time. At each N, transition probabilities in these systems can be found analytically and exactly but complexity and variety of solutions in this class also grow with N quickly. We illustrate how common features of solvable MLZ systems appear from quantum integrability and develop an approach to further classification of solvable MLZ problems.

  18. Validity of the lowest-Landau-level approximation for rotating Bose gases

    International Nuclear Information System (INIS)

    Morris, Alexis G.; Feder, David L.

    2006-01-01

    The energy spectrum for an ultracold rotating Bose gas in a harmonic trap is calculated exactly for small systems, allowing the atoms to occupy several Landau levels. Two vortexlike states and two strongly correlated states (the Pfaffian and Laughlin) are considered in detail. In particular, their critical rotation frequencies and energy gaps are determined as a function of particle number, interaction strength, and the number of Landau levels occupied (up to three). For the vortexlike states, the lowest-Landau-level (LLL) approximation is justified only if the interaction strength decreases with the number of particles; nevertheless, the constant of proportionality increases rapidly with the angular momentum per particle. For the strongly correlated states, however, the interaction strength can increase with particle number without violating the LLL condition. The results suggest that, in large systems, the Pfaffian and Laughlin states might be stabilized at rotation frequencies below the centrifugal limit for sufficiently large interaction strengths, with energy gaps a significant fraction of the trap energy

  19. Splitting of the zero-energy Landau level and universal dissipative conductivity at critical points in disordered graphene.

    Science.gov (United States)

    Ortmann, Frank; Roche, Stephan

    2013-02-22

    We report on robust features of the longitudinal conductivity (σ(xx)) of the graphene zero-energy Landau level in the presence of disorder and varying magnetic fields. By mixing an Anderson disorder potential with a low density of sublattice impurities, the transition from metallic to insulating states is theoretically explored as a function of Landau-level splitting, using highly efficient real-space methods to compute the Kubo conductivities (both σ(xx) and Hall σ(xy)). As long as valley degeneracy is maintained, the obtained critical conductivity σ(xx) =/~ 1.4e(2)/h is robust upon an increase in disorder (by almost 1 order of magnitude) and magnetic fields ranging from about 2 to 200 T. When the sublattice symmetry is broken, σ(xx) eventually vanishes at the Dirac point owing to localization effects, whereas the critical conductivities of pseudospin-split states (dictating the width of a σ(xy) = 0 plateau) change to σ(xx) =/~ e(2)/h, regardless of the splitting strength, superimposed disorder, or magnetic strength. These findings point towards the nondissipative nature of the quantum Hall effect in disordered graphene in the presence of Landau level splitting.

  20. Landau-Lifshitz sigma-models, fermions and the AdS/CFT correspondence

    OpenAIRE

    Stefanski Jr, B.

    2007-01-01

    We define Landau-Lifshitz sigma models on general coset space $G/H$, with $H$ a maximal stability sub-group of $G$. These are non-relativistic models that have $G$-valued N\\"other charges, local $H$ invariance and are classically integrable. Using this definition, we construct the $PSU(2,2|4)/PS(U(2|2)^2)$ Landau-Lifshitz sigma-model. This sigma model describes the thermodynamic limit of the spin-chain Hamiltonian obtained from the complete one-loop dilatation operator of the N=4 super Yang-M...

  1. Multiparticle phenomena and Landau damping

    International Nuclear Information System (INIS)

    Talman, R.

    1987-01-01

    The purpose of this paper is to survey various methods of studying multiparticle phenomena in accelerators. Both experimental and theoretical methods are described. An effort has been made to emphasize the intuitive and qualitative aspects rather than the detailed mathematics. Some of the terms or concepts to be explained are coherent and incoherent tunes, normal modes, Landau damping, beam-transfer functions, and feedback. These are all of daily importance in the interpretation of colliding-beam observations and the control of performance

  2. Investigation of Landau level spin reversal in (110) oriented p-type GaAs quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Isik, Nebile

    2009-09-01

    In this thesis, the Landau level crossing or anticrossing of hole levels has been investigated in p-type GaAs 400 Aa wide quantum wells. In magneto-transport measurements, this is evidenced with the presence of an anomalous peak in the longitudinal resistance measurements at {nu}=1. In the transversal resistance measurements, no signature of this anomalous peak is observed. By increasing the hole density in the quantum well by applying a top gate voltage, the position of the anomalous peak shifts to higher magnetic fields. At very high densities, anomalous peak disappears. By applying a back gate voltage, the electric field in the quantum well is tuned. A consequence is that the geometry of the quantum well is tuned from square to triangular. The anomalous peak position is shown to depend also on the back gate voltage applied. Temperature dependence of the peak height is consistent with thermal activation energy gap ({delta}/2= 135 {mu}eV). The activation energy gap as a function of the magnetic field has a parabolic like dependence, with the minimum of 135 {mu}eV at 4 T. The peak magnitude is observed to decrease with increasing temperature. An additional peak is observed at {nu}=2 minimum. This additional peak at {nu}=2 might be due to the higher Landau level crossing. The p-type quantum wells have been investigated by photoluminescence spectroscopy, as a function of the magnetic field. The polarization of the emitted light has been analyzed in order to distinguish between the transitions related to spin of electron {+-} 1/2 and spin of hole -+ 3/2. The transition energies of the lowest electron Landau levels with spin {+-} 1/2 and hole Landau levels with spin -+ 3/2 versus magnetic field show crossing at 4 T. The heavy hole Landau levels with spins {+-} 3/2 are obtained by the substraction of transition energies from the sum of lowest electron Landau level energy and the energy gap of GaAs. The heavy hole Landau levels show a crossing at 4 T. However, due to the

  3. Research in theoretical nuclear physics. Progress report, August 1, 1982-January 31, 1984

    International Nuclear Information System (INIS)

    Liu, K.F.

    1984-01-01

    The short-range NN deformation potential is calculated in the MIT bag model with several corrections. The color van der Waals force is derived in the coupled channel formalism. The baryon spectrum is studied with the potentials fitted to meson masses. The production of multi-quark hadrons which decay to vector-meson pairs are studied in γγ reactions, hadronic collisions, J/psi radiative decays and relativistic heavy ion collisions. The feasibility of 81 Br as a solar neutrino detector is studied by estimating the solar neutrino capture rate using information from the charge exchange reactions. Landau sum rules are applied to examine the Landau-Migdal parameters. An extended Skyrme-Landau interaction is being developed. Landau damping in the nuclear matter is being calculated. 14 references

  4. Electron Landau damping of ion Bernstein waves in tokamak plasmas

    International Nuclear Information System (INIS)

    Brambilla, M.

    1998-01-01

    Absorption of ion Bernstein (IB) waves by electrons is investigated. These waves are excited by linear mode conversion in tokamak plasmas during fast wave (FW) heating and current drive experiments in the ion cyclotron range of frequencies. Near mode conversion, electromagnetic corrections to the local dispersion relation largely suppress electron Landau damping of these waves, which becomes important again, however, when their wavelength is comparable to the ion Larmor radius or shorter. The small Larmor radius wave equations solved by most numerical codes do not correctly describe the onset of electron Landau damping at very short wavelengths, and these codes, therefore, predict very little damping of IB waves, in contrast to what one would expect from the local dispersion relation. We present a heuristic, but quantitatively accurate, model which allows account to be taken of electron Landau damping of IB waves in such codes, without affecting the damping of the compressional wave or the efficiency of mode conversion. The possibilities and limitations of this approach are discussed on the basis of a few examples, obtained by implementing this model in the toroidal axisymmetric full wave code TORIC. (author)

  5. Theoretical studies of multistep processes, isospin effects in nuclear scattering, and meson and baryon interactions in nuclear physics. Final technical report, 1 September 1979-30 April 1986

    International Nuclear Information System (INIS)

    Madsen, V.A.; Landau, R.H.

    1986-01-01

    Final technical report on a contract supporting theoretical studies in nuclear physics at Oregon State University is presented. The research was led by Professors Landau and Madsen and carried out in collaboration with graduate students in Corvallis and scientists at LLNL-Livermore, KFA-Julich, Purdue University-West Lafayette, University of Oregon-Eugene, Florida State University-Talahasie, and TRIUMF-Vancouver. The studies included meson exchange current effects, quark effects,and relativistic/Dirac effects deduced from spin observables in p- 3 He scattering, coupled bound and continuum eigenstates in momentum space for kaons and antiprotons, and charge symmetry violation in π scattering from trinucleons. Additional studies included microscopic optical potential calculations, multiple step processes, and differences in neutron and proton multipole matrix elements in low lying collective states and in giant resonances. 45 refs

  6. Under the spell of Landau when theoretical physics was shaping destinies

    CERN Document Server

    2013-01-01

    This invaluable collection of memoirs and reviews on scientific activities of the most prominent theoretical physicists belonging to the Landau School - Landau, Anselm, Gribov, Zeldovich, Kirzhnits, Migdal, Ter-Martirosyan and Larkin - are being published in English for the first time. The main goal is to acquaint readers with the life and work of outstanding Soviet physicists who, to a large extent, shaped theoretical physics in the 1950s - 70s. Many intriguing details have remained unknown beyond the "Iron Curtain" which was dismantled only with the fall of the USSR.

  7. Terahertz imaging of Landau levels in HgTe-based topological insulators

    Energy Technology Data Exchange (ETDEWEB)

    Kadykov, Aleksandr M.; Krishtopenko, Sergey S. [Laboratoire Charles Coulomb (L2C), UMR 5221 CNRS–Université de Montpellier, Montpellier (France); Institute for Physics of Microstructures, Russian Academy of Sciences, GSP-105, 603950 Nizhny Novgorod (Russian Federation); Torres, Jeremie [Institut d' Electronique et des Systèmes (IES), UMR 5214 CNRS–Université de Montpellier, Montpellier (France); Consejo, Christophe; Ruffenach, Sandra; Marcinkiewicz, Michal; But, Dmytro; Teppe, Frederic, E-mail: frederic.teppe@umontpellier.fr [Laboratoire Charles Coulomb (L2C), UMR 5221 CNRS–Université de Montpellier, Montpellier (France); Knap, Wojciech [Laboratoire Charles Coulomb (L2C), UMR 5221 CNRS–Université de Montpellier, Montpellier (France); Institute of High Pressure Institute Physics, Polish Academy of Sciences, 01-447 Warsaw (Poland); Morozov, Sergey V.; Gavrilenko, Vladimir I. [Institute for Physics of Microstructures, Russian Academy of Sciences, GSP-105, 603950 Nizhny Novgorod (Russian Federation); Lobachevsky State University of Nizhny Novgorod, 603950 Nizhny Novgorod (Russian Federation); Mikhailov, Nikolai N. [Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, pr. Akademika Lavrent' eva 13, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 630090 Novosibirsk (Russian Federation); Dvoretsky, Sergey A. [Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, pr. Akademika Lavrent' eva 13, 630090 Novosibirsk (Russian Federation)

    2016-06-27

    We report on sub-terahertz photoconductivity under the magnetic field of a two dimensional topological insulator based on HgTe quantum wells. We perform a detailed visualization of Landau levels by means of photoconductivity measured at different gate voltages. This technique allows one to determine a critical magnetic field, corresponding to topological phase transition from inverted to normal band structure, even in almost gapless samples. The comparison with realistic calculations of Landau levels reveals a smaller role of bulk inversion asymmetry in HgTe quantum wells than it was assumed previously.

  8. Landau levels from neutral Bogoliubov particles in two-dimensional nodal superconductors under strain and doping gradients

    Science.gov (United States)

    Nica, Emilian M.; Franz, Marcel

    2018-02-01

    Motivated by recent work on strain-induced pseudomagnetic fields in Dirac and Weyl semimetals, we analyze the possibility of analogous fields in two-dimensional nodal superconductors. We consider the prototypical case of a d -wave superconductor, a representative of the cuprate family, and find that the presence of weak, spatially varying strain leads to pseudomagnetic fields and Landau quantization of Bogoliubov quasiparticles in the low-energy sector. A similar effect is induced by the presence of generic, weak doping gradients. In contrast to genuine magnetic fields in superconductors, the strain- and doping-gradient-induced pseudomagnetic fields couple in a way that preserves time-reversal symmetry and is not subject to the screening associated with the Meissner effect. These effects can be probed by tuning weak applied supercurrents which lead to shifts in the energies of the Landau levels and hence to quantum oscillations in thermodynamic and transport quantities.

  9. Ensemble inequivalence: Landau theory and the ABC model

    International Nuclear Information System (INIS)

    Cohen, O; Mukamel, D

    2012-01-01

    It is well known that systems with long-range interactions may exhibit different phase diagrams when studied within two different ensembles. In many of the previously studied examples of ensemble inequivalence, the phase diagrams differ only when the transition in one of the ensembles is first order. By contrast, in a recent study of a generalized ABC model, the canonical and grand-canonical ensembles of the model were shown to differ even when they both exhibit a continuous transition. Here we show that the order of the transition where ensemble inequivalence may occur is related to the symmetry properties of the order parameter associated with the transition. This is done by analyzing the Landau expansion of a generic model with long-range interactions. The conclusions drawn from the generic analysis are demonstrated for the ABC model by explicit calculation of its Landau expansion. (paper)

  10. Adiabatic evolution, quantum phases, and Landau-Zener transitions in strong radiation fields

    International Nuclear Information System (INIS)

    Breuer, H.P.; Dietz, K.; Holthaus, M.

    1990-07-01

    We develop a method that allows the investigation of adiabatic evolution in periodically driven quantum systems. It is shown how Berry's geometrical phase emerges in quantum optics. We analyse microwave experiments performed on Rydberg atoms and suggest a new, non-perturbative mechanism to produce excited atomic states. (orig.)

  11. Study of supersaturation of defects under neutron irradiation by Zener relaxation

    International Nuclear Information System (INIS)

    Gonzalez, Hector C.; Justus, Francisco J.W.

    2004-01-01

    Vacancy supersaturation in dynamic equilibrium under fast neutron irradiation could be determined by anelastic relaxation. This phenomenon is particularly noticeable in some substitutional binary alloys. Relaxation is due to the reordering of atoms pairs under a stress, being a local reordering at the atomic scale. Relaxation time (τ) is inversely proportional to the vacancy concentration (Cv) and decreases under irradiation because a dynamical equilibrium of vacancy concentration, higher than thermodynamic equilibrium, is established. Theoretical models allow estimating the magnitude of that supersaturation. Determinations of τ at different temperatures, with and without fast neutron irradiations, were made with an 'in situ' device placed in the high temperature loop in the RA1 CAC-CNEA reactor. An alloy Au-30% Ni was used, since it presents an appreciable Zener effect. The measurements were performed in a spring-shaped specimen in order to minimize temperature and flux gradients. An Arrhenius plot of τ was obtained, and it was observed that for temperatures lower than 220 C degrees a vacancy supersaturation exists. The lowest temperature of our experiments was 190 C degrees. A value of τ at this temperature was three times lower under irradiations. A plot of τ vs. fast neutron fluence (φ f t) at the irradiation temperature T= 203 C degrees was obtained. An increase of τ was observed. After an annealing at T = 280 C degrees, the value of τ recovers the value corresponding to the unirradiated case. This fact suggests that the loops produced by irradiation act as defect sinks. (author) [es

  12. Landau-level spectroscopy of massive Dirac fermions in single-crystalline ZrTe5 thin flakes

    Science.gov (United States)

    Jiang, Y.; Dun, Z. L.; Zhou, H. D.; Lu, Z.; Chen, K.-W.; Moon, S.; Besara, T.; Siegrist, T. M.; Baumbach, R. E.; Smirnov, D.; Jiang, Z.

    2017-07-01

    We report infrared magnetospectroscopy studies on thin crystals of an emerging Dirac material ZrTe5 near the intrinsic limit. The observed structure of the Landau-level transitions and zero-field infrared absorption indicate a two-dimensional Dirac-like electronic structure, similar to that in graphene but with a small relativistic mass corresponding to a 9.4-meV energy gap. Measurements with circularly polarized light reveal a significant electron-hole asymmetry, which leads to splitting of the Landau-level transitions at high magnetic fields. Our model, based on the Bernevig-Hughes-Zhang effective Hamiltonian, quantitatively explains all observed transitions, determining the values of the Fermi velocity, Dirac mass (or gap), electron-hole asymmetry, and electron and hole g factors.

  13. I. Nuclear and neutron matter calculations with isobars. II. A model calculation of Fermi liquid parameters for liquid 3He

    International Nuclear Information System (INIS)

    Ainsworth, T.L.

    1983-01-01

    The Δ(1232) plays an important role in determining the properties of nuclear and neutron matter. The effects of the Δ resonance are incorporated explicitly by using a coupled channel formalism. A method for constraining a lowest order variational calculation, appropriate when nucleon internal degrees of freedom are made explicity, is presented. Different N-N potentials were calculated and fit to phase shift data and deuteron properties. The potentials were constructed to test the relative importance of the Δ resonance on nuclear properties. The symmetry energy and incompressibility of nuclear matter are generally reproduced by this calculation. Neutron matter results lead to appealing neutron star models. Fermi liquid parameters for 3 He are calculated with a model that includes both direct and induced terms. A convenient form of the direct interaction is obtained in terms of the parameters. The form of the direct interaction ensures that the forward scattering sum rule (Pauli principle) is obeyed. The parameters are adjusted to fit the experimentally determined F 0 /sup s/, F 0 /sup a/, and F 1 /sup s/ Landau parameters. Higher order Landau parameters are calculated by the self-consistent solution of the equations; comparison to experiment is good. The model also leads to a preferred value for the effective mass of 3 He. Of the three parameters only one shows any dependence on pressure. An exact sum rule is derived relating this parameter to a specific summation of Landau parameters

  14. Ginzburg-Landau equation as a heuristic model for generating rogue waves

    Science.gov (United States)

    Lechuga, Antonio

    2016-04-01

    Envelope equations have many applications in the study of physical systems. Particularly interesting is the case 0f surface water waves. In steady conditions, laboratory experiments are carried out for multiple purposes either for researches or for practical problems. In both cases envelope equations are useful for understanding qualitative and quantitative results. The Ginzburg-Landau equation provides an excellent model for systems of that kind with remarkable patterns. Taking into account the above paragraph the main aim of our work is to generate waves in a water tank with almost a symmetric spectrum according to Akhmediev (2011) and thus, to produce a succession of rogue waves. The envelope of these waves gives us some patterns whose model is a type of Ginzburg-Landau equation, Danilov et al (1988). From a heuristic point of view the link between the experiment and the model is achieved. Further, the next step consists of changing generating parameters on the water tank and also the coefficients of the Ginzburg-Landau equation, Lechuga (2013) in order to reach a sufficient good approach.

  15. Multiple Walkers in the Wang-Landau Algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Brown, G

    2005-12-28

    The mean cost for converging an estimated density of states using the Wang-Landau algorithm is measured for the Ising and Heisenberg models. The cost increases in a power-law fashion with the number of spins, with an exponent near 3 for one-dimensional models, and closer to 2.4 for two-dimensional models. The effect of multiple, simultaneous walkers on the cost is also measured. For the one-dimensional Ising model the cost can increase with the number of walkers for large systems. For both the Ising and Heisenberg models in two-dimensions, no adverse impact on the cost is observed. Thus multiple walkers is a strategy that should scale well in a parallel computing environment for many models of magnetic materials.

  16. Improved Landau gauge fixing and discretisation errors

    International Nuclear Information System (INIS)

    Bonnet, F.D.R.; Bowman, P.O.; Leinweber, D.B.; Richards, D.G.; Williams, A.G.

    2000-01-01

    Lattice discretisation errors in the Landau gauge condition are examined. An improved gauge fixing algorithm in which O(a 2 ) errors are removed is presented. O(a 2 ) improvement of the gauge fixing condition displays the secondary benefit of reducing the size of higher-order errors. These results emphasise the importance of implementing an improved gauge fixing condition

  17. Use of riser tube rotation equipment in the Emlichheim and Landau petroleum mines of Wintershall AG Erdoelwerke; Einsatz von Steigrohrdrehvorrichtungen in den Erdoelfoerderbetrieben Emlichheim und Landau der Wintershall AG Erdoelwerke

    Energy Technology Data Exchange (ETDEWEB)

    Caspari, R. [Wintershall AG Erdoelwerke, Emlichheim (Germany)

    1998-12-31

    Riser tube rotation equipment has been in use in the Emlichheim and Landau petroleum wells since 1994 in order to ensure longer life of the riser tubes. (orig.) [Deutsch] In den von Wintershall operierten Erdoelfoerderbetrieben Emlichheim und Landau werden ca. 90% der Bohrungen mit Gestaengetiefpumpen gefoerdert. Aufgrund der lagerstaettentechnischen Gegebenheiten, der Thermalmassnahmen in Emlichheim und der Infrastruktur der Betriebe koennen andere Foerderhilfsmittel wie Tauchkreiselpumpe, Excenterschneckenpumpe oder Gasliften nur bedingt zum Einsatz kommen. Ein wesentlicher Faktor fuer den wirtschaftlichen Betrieb dieser Bohrungen sind die Aufwaeltigungen zur Beseitigung von Schaeden an der Tiefpumpe, dem Pumpgestaenge und den Steigrohren. Waehrend die Einsatzdauer der Tiefpumpen und des Pumpgestaenges durch hoeherwertige Materialguete und geeignete Optimierungsmassnahmen erhoeht werden konnten, sind die Standzeiten der Steigrohre nahezu unveraendert geblieben. Um diese zu erhoehen, werden in den Erdoelfoerderbetrieben Emlichheim und Landau seit April 1994 Steigrohrdrehvorrichtungen eingesetzt. (orig.)

  18. On the questions of the nuclear level density and the E1 photon strength functions

    International Nuclear Information System (INIS)

    Mughabghab, S.F.; Dunford, C.L.

    1999-01-01

    New results were derived from average level spacings of neutron resonances for the spin dispersion parameter of the nuclear level density, which demonstrated the influence of shell effects, as well as the interplay of nucleon pairing correlations for nuclei in the mass range from 29 Si to 241 Pu. The volume and surface components of the nuclear level density parameter, as well as the shell-damping factor, were determined as, a v = 0.076 ± 0.009 MeV -1 , a s = 0.180 ± 0.047 MeV -1 , and y 0 = 0.047 ± 0.04 MeV±, respectively. The effective nucleon mass at the Fermi surface is derived as m*/m = 1.09 ± 0.13. New evidence is presented for a dipole-quadrupole interaction term in the primary E1 transitions of average resonance capture data. This evidence is obtained by testing a proposed generalized Landau Fermi liquid model for spherical and deformed nuclei, which includes the effect of the dipole-quadrupole interaction. The Landau-Migdal interaction constant and the effective nucleon mass, are determined as F 0 prime = 1.49 ± 0.08, and m*/m=1.04 ± 0.07, respectively

  19. Excited Landau levels, orbital angular momentum and axial anomaly

    International Nuclear Information System (INIS)

    Teryaev, O.V.

    1993-01-01

    The IR cutoff via the exclusion of the high orbital momentum components for the excited Landau levels leads to the physical interpretation of the cancellation between the explicity and anomalous chiral symmetry breaking. 21 refs

  20. Bose-Einstein correlation in Landau's model

    International Nuclear Information System (INIS)

    Hama, Y.; Padula, S.S.

    1986-01-01

    Bose-Einstein correlation is studied by taking an expanding fluid given by Landau's model as the source, where each space-time point is considered as an independent and chaotic emitting center with Planck's spectral distribution. As expected, the correlation depends on the relative angular positions as well as on the overall localization of the measuring system and it turns out that the average dimension of the source increases with the multiplicity N/sub ch/

  1. Dyson-Schwinger equations and N = 4 SYM in Landau gauge

    Energy Technology Data Exchange (ETDEWEB)

    Maas, Axel; Zitz, Stefan [University of Graz, Institute of Physics, NAWI Graz, Graz (Austria)

    2016-03-15

    N = 4 Super Yang-Mills theory is a highly constrained theory, and therefore a valuable tool to test the understanding of less constrained Yang-Mills theories. Our aim is to use it to test our understanding of both the Landau gauge beyond perturbation theory and the truncations of Dyson-Schwinger equations in ordinary Yang-Mills theories. We derive the corresponding equations within the usual one-loop truncation for the propagators after imposing the Landau gauge. We find a conformal solution in this approximation, which surprisingly resembles many aspects of ordinary Yang-Mills theories. We furthermore discuss which role the Gribov-Singer ambiguity in this context could play, should it exist in this theory. (orig.)

  2. The Landau-de Gennes theory of nematic liquid crystals: Uniaxiality versus Biaxiality

    KAUST Repository

    Majumdar, Apala

    2011-12-01

    We study small energy solutions within the Landau-de Gennes theory for nematic liquid crystals, subject to Dirichlet boundary conditions. We consider two-dimensional and three-dimensional domains separately. In the two-dimensional case, we establish the equivalence of the Landau-de Gennes and Ginzburg-Landau theory. In the three-dimensional case, we give a new definition of the defect set based on the normalized energy. In the threedimensional uniaxial case, we demonstrate the equivalence between the defect set and the isotropic set and prove the C 1,α-convergence of uniaxial small energy solutions to a limiting harmonic map, away from the defect set, for some 0 < a < 1, in the vanishing core limit. Generalizations for biaxial small energy solutions are also discussed, which include physically relevant estimates for the solution and its scalar order parameters. This work is motivated by the study of defects in liquid crystalline systems and their applications.

  3. Integrability and structural stability of solutions to the Ginzburg-Landau equation

    Science.gov (United States)

    Keefe, Laurence R.

    1986-01-01

    The integrability of the Ginzburg-Landau equation is studied to investigate if the existence of chaotic solutions found numerically could have been predicted a priori. The equation is shown not to possess the Painleveproperty, except for a special case of the coefficients that corresponds to the integrable, nonlinear Schroedinger (NLS) equation. Regarding the Ginzburg-Landau equation as a dissipative perturbation of the NLS, numerical experiments show all but one of a family of two-tori solutions, possessed by the NLS under particular conditions, to disappear under real perturbations to the NLS coefficients of O(10 to the -6th).

  4. Reversible dissipative processes, conformal motions and Landau damping

    International Nuclear Information System (INIS)

    Herrera, L.; Di Prisco, A.; Ibáñez, J.

    2012-01-01

    The existence of a dissipative flux vector is known to be compatible with reversible processes, provided a timelike conformal Killing vector (CKV) χ α =(V α )/T (where V α and T denote the four-velocity and temperature respectively) is admitted by the spacetime. Here we show that if a constitutive transport equation, either within the context of standard irreversible thermodynamics or the causal Israel–Stewart theory, is adopted, then such a compatibility also requires vanishing dissipative fluxes. Therefore, in this later case the vanishing of entropy production generated by the existence of such CKV is not actually associated to an imperfect fluid, but to a non-dissipative one. We discuss also about Landau damping. -- Highlights: ► We review the problem of compatibility of dissipation with reversibility. ► We show that the additional assumption of a transport equation renders such a compatibility trivial. ► We discuss about Landau damping.

  5. Gyro-Landau fluid model of tokamak core fluctuations

    International Nuclear Information System (INIS)

    Leboeuf, J.N.; Carreras, B.A.; Dominguez, N.; Hedrick, C.L.; Sidikman, K.L.; Lynch, V.E.; Drake, J.B.; Walker, D.W.

    1992-01-01

    Dissipative trapped electron modes (DTEM) may be one of the causes of deterioration of confinement in tokamak and stellatator plasmas. We have implemented a fluid model to study DTEM turbulence in slab geometry. The electron dynamics include in addition to the adiabatic part, a non-adiabatic piece modeled with an i-delta-type response. The ion dynamics include Landau damping and FLR corrections through Landau fluid approximate techniques and Pade approximants for Γ 0 (b)=I 0 (b)e -b . The model follows from the gyrokinetic equation. Evolution equations, which closely resemble those used in standard reduced MHD, are presented since these are better suited to non-linear calculations. The numerical results of radially resolved calculations will be discussed. A recently developed hybrid model, which consists of a gyrokinetic implementation for the ions using particles and the same description for the electron dynamics as in the fluid model, will also be presented

  6. Reversible dissipative processes, conformal motions and Landau damping

    Energy Technology Data Exchange (ETDEWEB)

    Herrera, L., E-mail: laherrera@cantv.net.ve [Departamento de Física Teórica e Historia de la Ciencia, Universidad del País Vasco, Bilbao (Spain); Di Prisco, A., E-mail: adiprisc@fisica.ciens.ucv.ve [Departamento de Física Teórica e Historia de la Ciencia, Universidad del País Vasco, Bilbao (Spain); Ibáñez, J., E-mail: j.ibanez@ehu.es [Departamento de Física Teórica e Historia de la Ciencia, Universidad del País Vasco, Bilbao (Spain)

    2012-02-06

    The existence of a dissipative flux vector is known to be compatible with reversible processes, provided a timelike conformal Killing vector (CKV) χ{sup α}=(V{sup α})/T (where V{sup α} and T denote the four-velocity and temperature respectively) is admitted by the spacetime. Here we show that if a constitutive transport equation, either within the context of standard irreversible thermodynamics or the causal Israel–Stewart theory, is adopted, then such a compatibility also requires vanishing dissipative fluxes. Therefore, in this later case the vanishing of entropy production generated by the existence of such CKV is not actually associated to an imperfect fluid, but to a non-dissipative one. We discuss also about Landau damping. -- Highlights: ► We review the problem of compatibility of dissipation with reversibility. ► We show that the additional assumption of a transport equation renders such a compatibility trivial. ► We discuss about Landau damping.

  7. Estimating the Partition Function Zeros by Using the Wang-Landau Monte Carlo Algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seung-Yeon [Korea National University of Transportation, Chungju (Korea, Republic of)

    2017-03-15

    The concept of the partition function zeros is one of the most efficient methods for investigating the phase transitions and the critical phenomena in various physical systems. Estimating the partition function zeros requires information on the density of states Ω(E) as a function of the energy E. Currently, the Wang-Landau Monte Carlo algorithm is one of the best methods for calculating Ω(E). The partition function zeros in the complex temperature plane of the Ising model on an L × L square lattice (L = 10 ∼ 80) with a periodic boundary condition have been estimated by using the Wang-Landau Monte Carlo algorithm. The efficiency of the Wang-Landau Monte Carlo algorithm and the accuracies of the partition function zeros have been evaluated for three different, 5%, 10%, and 20%, flatness criteria for the histogram H(E).

  8. On translational superfluidity and the Landau criterion for Bose gases in the Gross-Pitaevski limit

    International Nuclear Information System (INIS)

    Wreszinski, Walter F

    2008-01-01

    The two-fluid and Landau criteria for superfluidity are compared for trapped Bose gases. While the two-fluid criterion predicts translational superfluidity, it is suggested, on the basis of the homogeneous Gross-Pitaevski limit, that a necessary part of Landau's criterion, adequate for non-translationally invariant systems, does not hold for trapped Bose gases in the GP limit. As a consequence, if the compressibility is detected to be very large (infinite by experimental standards), the two-fluid criterion is seen to be the relevant one in case the system is a translational superfluid, while the Landau criterion is the relevant one if translational superfluidity is absent. (fast track communication)

  9. Landau-Ginzburg Limit of Black Hole's Quantum Portrait: Self Similarity and Critical Exponent

    CERN Document Server

    Dvali, Gia

    2012-01-01

    Recently we have suggested that the microscopic quantum description of a black hole is an overpacked self-sustained Bose-condensate of N weakly-interacting soft gravitons, which obeys the rules of 't Hooft's large-N physics. In this note we derive an effective Landau-Ginzburg Lagrangian for the condensate and show that it becomes an exact description in a semi-classical limit that serves as the black hole analog of 't Hooft's planar limit. The role of a weakly-coupled Landau-Ginzburg order parameter is played by N. This description consistently reproduces the known properties of black holes in semi-classical limit. Hawking radiation, as the quantum depletion of the condensate, is described by the slow-roll of the field N. In the semiclassical limit, where black holes of arbitrarily small size are allowed, the equation of depletion is self similar leading to a scaling law for the black hole size with critical exponent 1/3.

  10. Episodic epileptic verbal auditory agnosia in Landau Kleffner syndrome treated with combination diazepam and corticosteroids.

    Science.gov (United States)

    Devinsky, Orrin; Goldberg, Rina; Miles, Daniel; Bojko, Aviva; Riviello, James

    2014-10-01

    We report 2 pediatric patients who presented initially with seizures followed by subacute language regression characterized by a verbal auditory agnosia. These previously normal children had no evidence of expressive aphasia during their symptomatic periods. Further, in both cases, auditory agnosia was associated with sleep-activated electroencephalographic (EEG) epileptiform activity, consistent with Landau-Kleffner syndrome. However, both cases are unique since the episodic auditory agnosia and sleep-activated EEG epileptiform activity rapidly responded to combination therapy with pulse benzodiazepine and corticosteroids. Further, in each case, recurrences were characterized by similar symptoms, EEG findings, and beneficial responses to the pulse benzodiazepine and corticosteroid therapy. These observations suggest that pulse combination high-dose corticosteroid and benzodiazepine therapy may be especially effective in Landau-Kleffner syndrome. © The Author(s) 2014.

  11. Exact solutions of generalized Zakharov and Ginzburg-Landau equations

    International Nuclear Information System (INIS)

    Zhang Jinliang; Wang Mingliang; Gao Kequan

    2007-01-01

    By using the homogeneous balance principle, the exact solutions of the generalized Zakharov equations and generalized Ginzburg-Landau equation are obtained with the aid of a set of subsidiary higher-order ordinary differential equations (sub-equations for short)

  12. Non-adiabatic Landau-Zener transitions in low-spin molecular magnet V sub 1 sub 5

    CERN Document Server

    Chiorescu, I; Müller, A; Bögge, H; Barbara, B

    2000-01-01

    The V sub 1 sub 5 polyoxovanadate molecule is made of 15 spins ((1)/(2)) with antiferromagnetic couplings. It belongs to the class of molecules with very large Hilbert space dimension (2 sup 1 sup 5 in V sub 1 sub 5 , 10 sup 8 in Mn sub 1 sub 2 -AC). It is a low spin/large molecule with spin S=((1)/(2)). Contrary to large spins/large molecules of the Mn sub 1 sub 2 -AC type, V sub 1 sub 5 has no energy barrier against spin rotation. Magnetization measurements have been performed and despite the absence of a barrier, magnetic hysteresis is observed over a timescale of several seconds. This new phenomenon characterized by a 'butterfly' hysteresis loop is due to the effect of the environment on the quantum rotation of the entangled 15 spins of the molecule, in which the phonon density of states is not at its equilibrium (phonon bottleneck).

  13. Verifying the Kugo-Ojima Confinement Criterion in Landau Gauge Yang-Mills Theory

    International Nuclear Information System (INIS)

    Watson, Peter; Alkofer, Reinhard

    2001-01-01

    Expanding the Landau gauge gluon and ghost two-point functions in a power series we investigate their infrared behavior. The corresponding powers are constrained through the ghost Dyson-Schwinger equation by exploiting multiplicative renormalizability. Without recourse to any specific truncation we demonstrate that the infrared powers of the gluon and ghost propagators are uniquely related to each other. Constraints for these powers are derived, and the resulting infrared enhancement of the ghost propagator signals that the Kugo-Ojima confinement criterion is fulfilled in Landau gauge Yang-Mills theory

  14. The dispersion-managed Ginzburg–Landau equation and its application to femtosecond lasers

    International Nuclear Information System (INIS)

    Biondini, Gino

    2008-01-01

    The complex Ginzburg–Landau equation has been used extensively to describe various nonequilibrium phenomena. In the context of lasers, it models the dynamics by averaging over the effects that take place inside the cavity. Pulses produced by Ti : sapphire femtosecond lasers, however, undergo significant changes in different parts of the cavity during each round-trip. The dynamics of such pulses is therefore not adequately described by an average model that does not take such changes into account. The purpose of this work is severalfold. We introduce the dispersion-managed Ginzburg–Landau equation (DMGLE) as an average model that describes the long-term dynamics of systems characterized by rapid variations of dispersion, nonlinearity and gain in a general setting, and we study the properties of the equation. We then explain how in particular the DMGLE arises for Ti : sapphire femtosecond lasers and we characterize its solutions. In particular, we show that, for moderate values of the gain/loss parameters, the solutions of the DMGLE are well approximated by those of the dispersion-managed nonlinear Schrödinger equation (DMNLSE), and the main effect of gain and loss dynamics is simply to select one among the one-parameter family of solutions of the DMNLSE

  15. Drift of Spiral Waves in Complex Ginzburg-Landau Equation

    International Nuclear Information System (INIS)

    Yang Junzhong; Zhang Mei

    2006-01-01

    The spontaneous drift of the spiral wave in a finite domain in the complex Ginzburg-Landau equation is investigated numerically. By using the interactions between the spiral wave and its images, we propose a phenomenological theory to explain the observations.

  16. Magneto-transport in the zero-energy Landau level of single-layer and bilayer graphene

    International Nuclear Information System (INIS)

    Zeitler, U; Giesbers, A J M; Elferen, H J van; Kurganova, E V; McCollam, A; Maan, J C

    2011-01-01

    We present recent low-temperature magnetotransport experiments on single-layer and bilayer graphene in high magnetic field up to 33 T. In single layer graphene the fourfold degeneracy of the zero-energy Landau level is lifted by a gap opening at filling factor ν = 0. In bilayer graphene, we observe a partial lifting of the degeneracy of the eightfold degenerate zero-energy Landau level.

  17. Exactly soluble two-state quantum models with linear couplings

    International Nuclear Information System (INIS)

    Torosov, B T; Vitanov, N V

    2008-01-01

    A class of exact analytic solutions of the time-dependent Schroedinger equation is presented for a two-state quantum system coherently driven by a nonresonant external field. The coupling is a linear function of time with a finite duration and the detuning is constant. Four special models are considered in detail, namely the shark, double-shark, tent and zigzag models. The exact solution is derived by rotation of the Landau-Zener propagator at an angle of π/4 and is expressed in terms of Weber's parabolic cylinder function. Approximations for the transition probabilities are derived for all four models by using the asymptotics of the Weber function; these approximations demonstrate various effects of physical interest for each model

  18. Holography with a Landau pole

    Energy Technology Data Exchange (ETDEWEB)

    Faedo, Antón F. [Departament de Física Quántica i Astrofísica and Institut de Ciències del Cosmos (ICC), Universitat de Barcelona, Martí i Franquès 1, ES-08028, Barcelona (Spain); Mateos, David [Departament de Física Quántica i Astrofísica and Institut de Ciències del Cosmos (ICC), Universitat de Barcelona, Martí i Franquès 1, ES-08028, Barcelona (Spain); Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig Lluís Companys 23, ES-08010, Barcelona (Spain); Pantelidou, Christiana [Departament de Física Quántica i Astrofísica and Institut de Ciències del Cosmos (ICC), Universitat de Barcelona, Martí i Franquès 1, ES-08028, Barcelona (Spain); Tarrío, Javier [Physique Théorique et Mathématique, Université Libre de Bruxelles (ULB), and International Solvay Institutes, Campus de la Plaine CP 231, B-1050, Brussels (Belgium)

    2017-02-08

    Holography for UV-incomplete gauge theories is important but poorly understood. A paradigmatic example is d=4, N=4 super Yang-Mills coupled to N{sub f} quark flavors, which possesses a Landau pole at a UV scale Λ{sub LP}. The dual gravity solution exhibits a UV singularity at a finite proper distance along the holographic direction. Despite this, holographic renormalization can be fully implemented via analytic continuation to an AdS solution. The presence of a UV cut-off manifests itself in several interesting ways. At energies E≪Λ{sub LP} no pathologies appear, as expected from effective field theory. In contrast, at scales E≲Λ{sub LP} the gravitational potential becomes repulsive, and at temperatures T≲Λ{sub LP} the specific heat becomes negative. Although we focus on N=4 super Yang-Mills with flavor, our qualitative results apply to a much more general class of theories, since they only depend on the fact that the metric near the UV singularity is a hyper-scaling violating metric with exponent θ>d−1.

  19. Holography with a Landau pole

    International Nuclear Information System (INIS)

    Faedo, Antón F.; Mateos, David; Pantelidou, Christiana; Tarrío, Javier

    2017-01-01

    Holography for UV-incomplete gauge theories is important but poorly understood. A paradigmatic example is d=4, N=4 super Yang-Mills coupled to N f quark flavors, which possesses a Landau pole at a UV scale Λ LP . The dual gravity solution exhibits a UV singularity at a finite proper distance along the holographic direction. Despite this, holographic renormalization can be fully implemented via analytic continuation to an AdS solution. The presence of a UV cut-off manifests itself in several interesting ways. At energies E≪Λ LP no pathologies appear, as expected from effective field theory. In contrast, at scales E≲Λ LP the gravitational potential becomes repulsive, and at temperatures T≲Λ LP the specific heat becomes negative. Although we focus on N=4 super Yang-Mills with flavor, our qualitative results apply to a much more general class of theories, since they only depend on the fact that the metric near the UV singularity is a hyper-scaling violating metric with exponent θ>d−1.

  20. Irreducible diagrams in Landau-Ginzburg field theory

    Energy Technology Data Exchange (ETDEWEB)

    Witten, Jr, T A [Michigan Univ., Ann Arbor (USA). Dept. of Psychology

    1981-10-19

    It is shown that the free energy W of a Landau-Ginzburg-Wilson field theory with O(n) symmetry may be written in terms of the generating function V of diagrams irreducible in both propagator and interaction lines. This generalizes and simplifies a recent result of Des Cloizeaux. The functions W and V are related by a type of Legendre transformation on the bare mass variable.

  1. Landau Damping of Beam Instabilities by Electron Lenses

    Energy Technology Data Exchange (ETDEWEB)

    Shiltsev, V. [Fermilab; Alexahin, Yuri; Burov, A. [Fermilab; Valishev, A. [Fermilab

    2017-06-26

    Modern and future particle accelerators employ increasingly higher intensity and brighter beams of charged particles and become operationally limited by coherent beam instabilities. Usual methods to control the instabilities, such as octupole magnets, beam feedback dampers and use of chromatic effects, become less effective and insufficient. We show that, in contrast, Lorentz forces of a low-energy, a magnetically stabilized electron beam, or "electron lens", easily introduces transverse nonlinear focusing sufficient for Landau damping of transverse beam instabilities in accelerators. It is also important that, unlike other nonlinear elements, the electron lens provides the frequency spread mainly at the beam core, thus allowing much higher frequency spread without lifetime degradation. For the parameters of the Future Circular Collider, a single conventional electron lens a few meters long would provide stabilization superior to tens of thousands of superconducting octupole magnets.

  2. Effect of elastic compliances and higher order Landau coefficients on the phase diagram of single domain epitaxial Pb(Zr,TiO3 (PZT thin films

    Directory of Open Access Journals (Sweden)

    M. Mtebwa

    2014-12-01

    Full Text Available We report the qualitative study of the influence of both elastic compliances and higher order terms of Landau free energy potential on the phase diagram of Pb(Zr0.5Ti0.5O3 thin films by using a single domain Landau theory. Although the impact of elastic compliances and higher order terms of the Landau free energy potential on the phase diagram of ferroelectric thin films are known, the sensitivity of the phase diagram of PZT thin film on these parameters have not been reported. It is demonstrated that, while values of elastic compliances affect the positions of the phase boundaries including phase transition temperature of the cubic phase; higher order terms can potentially introduce an a1a2-phase previously predicted in PbTiO3 phase diagram.

  3. Thermal coupling effect on the vortex dynamics of superconducting thin films: time-dependent Ginzburg–Landau simulations

    Science.gov (United States)

    Jing, Ze; Yong, Huadong; Zhou, Youhe

    2018-05-01

    In this paper, vortex dynamics of superconducting thin films are numerically investigated by the generalized time-dependent Ginzburg–Landau (TDGL) theory. Interactions between vortex motion and the motion induced energy dissipation is considered by solving the coupled TDGL equation and the heat diffusion equation. It is found that thermal coupling has significant effects on the vortex dynamics of superconducting thin films. Branching in the vortex penetration path originates from the coupling between vortex motion and the motion induced energy dissipation. In addition, the environment temperature, the magnetic field ramp rate and the geometry of the superconducting film also greatly influence the vortex dynamic behaviors. Our results provide new insights into the dynamics of superconducting vortices, and give a mesoscopic understanding on the channeling and branching of vortex penetration paths during flux avalanches.

  4. On the Ginzburg-Landau critical field in three dimensions

    DEFF Research Database (Denmark)

    Fournais, Søren; Helffer, Bernard

    2009-01-01

    We study the three-dimensional Ginzburg-Landau model of superconductivity. Several natural definitions of the (third) critical field, HC3, governing the transition from the superconducting state to the normal state, are considered. We analyze the relation between these fields and give conditions ...

  5. Three-body interactions and the Landau levels using Nikiforov

    Indian Academy of Sciences (India)

    In this article, the eigenvalues for the three-body interactions on the line and the Landau levels in the presence of topological defects have been regenerated by the Nikiforov–Uvarov (NU) method. Two exhaustive lists of such exactly solvable potentials are given.

  6. Exact solutions to the Mo-Papas and Landau-Lifshitz equations

    Science.gov (United States)

    Rivera, R.; Villarroel, D.

    2002-10-01

    Two exact solutions of the Mo-Papas and Landau-Lifshitz equations for a point charge in classical electrodynamics are presented here. Both equations admit as an exact solution the motion of a charge rotating with constant speed in a circular orbit. These equations also admit as an exact solution the motion of two identical charges rotating with constant speed at the opposite ends of a diameter. These exact solutions allow one to obtain, starting from the equation of motion, a definite formula for the rate of radiation. In both cases the rate of radiation can also be obtained, with independence of the equation of motion, from the well known fields of a point charge, that is, from the Maxwell equations. The rate of radiation obtained from the Mo-Papas equation in the one-charge case coincides with the rate of radiation that comes from the Maxwell equations; but in the two-charge case the results do not coincide. On the other hand, the rate of radiation obtained from the Landau-Lifshitz equation differs from the one that follows from the Maxwell equations in both the one-charge and two-charge cases. This last result does not support a recent statement by Rohrlich in favor of considering the Landau-Lifshitz equation as the correct and exact equation of motion for a point charge in classical electrodynamics.

  7. Exact solutions to the Mo-Papas and Landau-Lifshitz equations

    International Nuclear Information System (INIS)

    Rivera, R.; Villarroel, D.

    2002-01-01

    Two exact solutions of the Mo-Papas and Landau-Lifshitz equations for a point charge in classical electrodynamics are presented here. Both equations admit as an exact solution the motion of a charge rotating with constant speed in a circular orbit. These equations also admit as an exact solution the motion of two identical charges rotating with constant speed at the opposite ends of a diameter. These exact solutions allow one to obtain, starting from the equation of motion, a definite formula for the rate of radiation. In both cases the rate of radiation can also be obtained, with independence of the equation of motion, from the well known fields of a point charge, that is, from the Maxwell equations. The rate of radiation obtained from the Mo-Papas equation in the one-charge case coincides with the rate of radiation that comes from the Maxwell equations; but in the two-charge case the results do not coincide. On the other hand, the rate of radiation obtained from the Landau-Lifshitz equation differs from the one that follows from the Maxwell equations in both the one-charge and two-charge cases. This last result does not support a recent statement by Rohrlich in favor of considering the Landau-Lifshitz equation as the correct and exact equation of motion for a point charge in classical electrodynamics

  8. Construction of the dual Ginzburg-Landau theory from the lattice QCD

    International Nuclear Information System (INIS)

    Suganuma, H.; Amemiya, K.; Ichie, H.; Koma, Y.

    2002-01-01

    We roughly review the QCD physics and then introduce recent topics on the confinement physics. In the maximally abelian (MA) gauge, the low-energy QCD is abelianized owing to the effective off-diagonal gluon mass M off ≅ 1.2 GeV induced by the MA gauge fixing. We demonstrate the construction of the dual Ginzburg-Landau (DGL) theory from the low-energy QCD in the MA gauge in terms of the lattice QCD evidences on infrared abelian dominance and infrared monopole condensation. (author)

  9. Ginsburg-Landau theory of two antagonistic order parameters: magnetism and superconductivity

    International Nuclear Information System (INIS)

    Suhl, H.

    1978-01-01

    An attempt is made to construct a Ginsburg-Landau theory of so-called magnetic superconductors. Two order parameters, the magnetization field and the gap function, are introduced in such a way as to inhibit each others growth. It is found that the non-local character of the superconducting order parameter must be taken into account in any evaluation of effects of the critical magnetic fluctuations. Some predictions are made within the limits of Ornstein-Zoernicke-like fluctuation theory and some comparison is made with available data. (Auth.)

  10. Integrable Time-Dependent Quantum Hamiltonians

    Science.gov (United States)

    Sinitsyn, Nikolai A.; Yuzbashyan, Emil A.; Chernyak, Vladimir Y.; Patra, Aniket; Sun, Chen

    2018-05-01

    We formulate a set of conditions under which the nonstationary Schrödinger equation with a time-dependent Hamiltonian is exactly solvable analytically. The main requirement is the existence of a non-Abelian gauge field with zero curvature in the space of system parameters. Known solvable multistate Landau-Zener models satisfy these conditions. Our method provides a strategy to incorporate time dependence into various quantum integrable models while maintaining their integrability. We also validate some prior conjectures, including the solution of the driven generalized Tavis-Cummings model.

  11. Electron capture in low- and intermediate-energy collisions between completely stripped light ions and metastable H(2s) targets

    International Nuclear Information System (INIS)

    Blanco, S.A.; Falcon, C.A.; Reinhold, C.O.; Casaubon, J.I.; Piacentini, R.D.

    1987-01-01

    Total cross sections for electron capture from H(2s) targets by He 2+ ions have been computed in the impact velocity range 0.05-0.5 au. Calculations were performed using a molecular close-coupling approach with inclusion of electron translation factors. A ten-state molecular basis set was considered. A comparison is made with Landau-Zener results for the same system. Intermediate projectile energy classical Monte Carlo capture cross sections are also presented for H + , He 2+ , Li 3+ and C 6+ projectiles. (author)

  12. Chiral algebras in Landau-Ginzburg models

    Science.gov (United States)

    Dedushenko, Mykola

    2018-03-01

    Chiral algebras in the cohomology of the {\\overline{Q}}+ supercharge of two-dimensional N=(0,2) theories on flat spacetime are discussed. Using the supercurrent multiplet, we show that the answer is renormalization group invariant for theories with an R-symmetry. For N=(0,2) Landau-Ginzburg models, the chiral algebra is determined by the operator equations of motion, which preserve their classical form, and quantum renormalization of composite operators. We study these theories and then specialize to the N=(2,2) models and consider some examples.

  13. Degeneracy of the lowest Landau level and suq(2) on the Poincare half plane

    International Nuclear Information System (INIS)

    Jellal, A.

    2000-01-01

    It is shown that the presence of the quantum group symmetry su q (2) in the quantum Hall effect on the Poincare upper half plane the degeneracy of the lowest Landau level. It is also shown that the relation between the degeneracy and the cyclic representation of su q (2) appears in accordance with q being a kth root of unity. (Authors)

  14. Ginzburg–Landau theory of mesoscopic multi-band Josephson junctions

    Energy Technology Data Exchange (ETDEWEB)

    Romeo, F.; De Luca, R., E-mail: rdeluca@unisa.it

    2017-05-15

    Highlights: • We generalize, in the realm of the Ginzburg–Landau theory, the de Gennes matching-matrix method for the interface order parameters to describe the superconducting properties of multi-band mesoscopic Josephson junctions. • The results are in agreement with a microscopic treatment of nanobridge junctions. • Thermal stability of the nanobridge junction is discussed in connection with recent experiments on iron-based grain-boundary junctions. - Abstract: A Ginzburg–Landau theory for multi-band mesoscopic Josephson junctions has been developed. The theory, obtained by generalizing the de Gennes matching-matrix method for the interface order parameters, allows the study of the phase dynamics of various types of mesoscopic Josephson junctions. As a relevant application, we studied mesoscopic double-band junctions also in the presence of a superconducting nanobridge interstitial layer. The results are in agreement with a microscopic treatment of the same system. Furthermore, thermal stability of the nanobridge junction is discussed in connection with recent experiments on iron-based grain-boundary junctions.

  15. Fractional Quantum Hall Effect in n = 0 Landau Band of Graphene with Chern Number Matrix

    Science.gov (United States)

    Kudo, Koji; Hatsugai, Yasuhiro

    2018-06-01

    Fully taking into account the honeycomb lattice structure, fractional quantum Hall states of graphene are considered by a pseudopotential projected into the n = 0 Landau band. By using chirality as an internal degree of freedom, the Chern number matrices are defined and evaluated numerically. Quantum phase transition induced by changing a range of the interaction is demonstrated that is associated with chirality ferromagnetism. The chirality-unpolarized ground state is consistent with the Halperin 331 state of the bilayer quantum Hall system.

  16. Hc2 of anisotropy two-band superconductors by Ginzburg-Landau approach

    International Nuclear Information System (INIS)

    Udomsamuthirun, P.; Changjan, A.; Kumvongsa, C.; Yoksan, S.

    2006-01-01

    The purpose of this research is to study the upper critical field H c2 of two-band superconductors by two-band Ginzburg-Landau approach. The analytical formula of H c2 included anisotropy of order parameter and anisotropy of effective-mass are found. The parameters of the upper critical field in ab-plane (H c2 - bar ab ) and c-axis (H c2 - bar c ) can be found by fitting to the experimental data. Finally, we can find the ratio of upper critical field that temperature dependent in the range of experimental result

  17. Theoretical studies of multistep processes, isospin effects in nuclear scattering, and meson and baryon interactions in nuclear physics: [Annual] progress report, May 1, 1986 to April 30, 1987

    International Nuclear Information System (INIS)

    Madsen, V.A.; Landau, R.H.

    1987-01-01

    A progress report on a grant from the DOE supporting theoretical studies in nuclear physics at Oregon State University in 1986, 1987 is presented. The research was led by Professors Landau and Madsen and carried out in collaboration with graduate students in Corvallis and scientists at LLNL-Livermore, KFA-Juelich, Purdue University, Florida State University and TRIUMF. The studies included meson exchange current effects deduced from spin observables in p- 3 He scattering, coupled bound and continuum eigenstates in momentum space for kaons and antiprotons, and charge symmetry violation in π scattering from trinucleons. Additional studies included microscopic optical potential calculations, multiple step processes, and differences in neutron and proton multipole matrix elements and transition densities in low lying collective states and in giant resonances

  18. Quantum resonances of Landau damping in the electromagnetic response of metallic nanoslabs.

    Science.gov (United States)

    Castillo-López, S G; Makarov, N M; Pérez-Rodríguez, F

    2018-05-15

    The resonant quantization of Landau damping in far-infrared absorption spectra of metal nano-thin films is predicted within the Kubo formalism. Specifically, it is found that the discretization of the electromagnetic and electron wave numbers inside a metal nanoslab produces quantum nonlocal resonances well-resolved at slab thicknesses smaller than the electromagnetic skin depth. Landau damping manifests itself precisely as such resonances, tracing the spectral curve obtained within the semiclassical Boltzmann approach. For slab thicknesses much greater than the skin depth, the classical regime emerges. Here the results of the quantum model and the Boltzmann approach coincide. Our analytical study is in perfect agreement with corresponding numerical simulations.

  19. Anisotropic harmonic oscillator, non-commutative Landau problem and exotic Newton-Hooke symmetry

    International Nuclear Information System (INIS)

    Alvarez, Pedro D.; Gomis, Joaquim; Kamimura, Kiyoshi; Plyushchay, Mikhail S.

    2008-01-01

    We investigate the planar anisotropic harmonic oscillator with explicit rotational symmetry as a particle model with non-commutative coordinates. It includes the exotic Newton-Hooke particle and the non-commutative Landau problem as special, isotropic and maximally anisotropic, cases. The system is described by the same (2+1)-dimensional exotic Newton-Hooke symmetry as in the isotropic case, and develops three different phases depending on the values of the two central charges. The special cases of the exotic Newton-Hooke particle and non-commutative Landau problem are shown to be characterized by additional, so(3) or so(2,1) Lie symmetry, which reflects their peculiar spectral properties

  20. Three-body interactions and the Landau levels using Nikiforov ...

    Indian Academy of Sciences (India)

    In this article, the eigenvalues for the three-body interactions on the line and the Landau levels in the presence of topological defects have been regenerated by the Nikiforov–Uvarov (NU) method. Two exhaustive lists of such exactly solvable potentials are given. Keywords. Nikiforov–Uvarov (NU) method; three-body ...

  1. The energy density of a Landau damped plasma wave

    NARCIS (Netherlands)

    Best, R. W. B.

    1999-01-01

    In this paper some theories about the energy of a Landau damped plasma wave are discussed and new initial conditions are proposed. Analysis of a wave packet, rather than an infinite wave, gives a clear picture of the energy transport from field to particles. Initial conditions are found which excite

  2. Effect of colored noise on the critical dynamics of the Time-Dependent Landau-Ginzburg Model A

    International Nuclear Information System (INIS)

    Korutcheva, E.; Rubia, J. de la

    1999-08-01

    By using the dynamical renormalization-group method, we show that the introduction of an additive colored noise with weak long-range correlations in the Time-Dependent Landau-Ginzburg Model A, does not give perturbative corrections for the dynamical critical exponent at least up to order O(ε 2 ). This result differs for a system with random quenched impurities, where a similar type of impurity correlation leads to corrections even of order O(ε). (author)

  3. Quantum tunneling of magnetization in molecular nanomagnet Fe8 studied by NMR

    International Nuclear Information System (INIS)

    Maegawa, Satoru; Ueda, Miki

    2003-01-01

    Magnetization and NMR measurements have been performed for single crystals of molecular magnet Fe8. The field and temperature dependences of magnetization below 25 K are well described in terms of the isolated clusters with the total spin S=10. The stepwise recoveries of 1 H-NMR signals at the level crossing fields caused by the resonant quantum tunneling of magnetization were observed below 400 mK. The recovery of the NMR signals are explained by the fluctuation caused by the transition between the energy states of Fe magnetizations governed by Landau-Zener quantum transitions

  4. Nonadiabatic ionic--covalent transitions. Exponential-linear model for the charge exchange and neutralization reactions Na+H arrow-right-left Na++H-

    International Nuclear Information System (INIS)

    Errea, L.F.; Mendez, L.; Mo, O.; Riera, A.

    1986-01-01

    A previous study of charge exchange processes taking place through ionic--covalent transitions is extended to the case of Na+H and Na + +H - collisions. A five-state molecular expansion, with the inclusion of two-electron translation factors, is employed to calculate the charge exchange and neutralization cross sections. Transitions at the first two pseudocrossings between the energy curves, practically determine the cross sections in the energy range 0.16--5 keV amu -1 . We also show that the widely used multichannel Landau--Zener theory is totally inadequate, to treat these transitions

  5. Nonadiabatic production of spinor condensates with a quadrupole-Ioffe-configuration trap

    International Nuclear Information System (INIS)

    Zhang, P.; Xu, Z.; You, L.

    2006-01-01

    Motivated by the recent experimental observation of multicomponent spinor condensates via a time-dependent quadrupole-Ioffe-configuration trap, we provide a general framework for the investigation of nonadiabatic Landau-Zener dynamics of a hyperfine spin, e.g., from an atomic magnetic dipole moment coupled to a weak time-dependent magnetic (B-) field. The spin flipped population distribution, or the so-called Majorona formula, is expressed in terms of system parameters and experimental observables; thus, the distribution provides much needed insight into the underlying mechanism for the production of spinor condensates due to nonadiabatic level crossings

  6. Dynamics of a Landau-Zener transitions in a two-level system driven by a dissipative environment

    Science.gov (United States)

    Ateuafack, M. E.; Diffo, J. T.; Fai, L. C.

    2016-02-01

    The paper investigates the effects of a two-level quantum system coupled to transversal and longitudinal dissipative environment. The time-dependent phase accumulation, LZ transition probability and entropy in the presence of fast-ohmic, sub-ohmic and super-ohmic quantum noise are derived. Analytical results are obtained in terms of temperature, dissipation strength, LZ parameter and bath cutoff frequency. The bath is observed to modify the standard occupation difference by a decaying random phase factor and also produces dephasing during the transfer of population. The dephasing characteristics or the initial non-zero decoherence rate are observed to increase in time with the bath temperature and depend on the system-bath coupling strength and cutoff frequency. These parameters are found to strongly affect the memory and thus tailor the coherence process of the system.

  7. Variations on the planar Landau problem: canonical transformations, a purely linear potential and the half-plane

    International Nuclear Information System (INIS)

    Govaerts, Jan; Hounkonnou, M Norbert; Mweene, Habatwa V

    2009-01-01

    The ordinary Landau problem of a charged particle in a plane subjected to a perpendicular homogeneous and static magnetic field is reconsidered from different points of view. The role of phase space canonical transformations and their relation to a choice of gauge in the solution of the problem is addressed. The Landau problem is then extended to different contexts, in particular the singular situation of a purely linear potential term being added as an interaction, for which a complete purely algebraic solution is presented. This solution is then exploited to solve this same singular Landau problem in the half-plane, with as motivation the potential relevance of such a geometry for quantum Hall measurements in the presence of an electric field or a gravitational quantum well.

  8. Variations on the planar Landau problem: canonical transformations, a purely linear potential and the half-plane

    Energy Technology Data Exchange (ETDEWEB)

    Govaerts, Jan [Center for Particle Physics and Phenomenology (CP3), Institut de Physique Nucleaire, Universite catholique de Louvain (UCL), 2, Chemin du Cyclotron, B-1348 Louvain-la Neuve (Belgium); Hounkonnou, M Norbert [International Chair in Mathematical Physics and Applications (ICMPA-UNESCO Chair), University of Abomey-Calavi, 072 BP 50, Cotonou (Benin); Mweene, Habatwa V [Physics Department, University of Zambia, PO Box 32379, Lusaka (Zambia)], E-mail: Jan.Govaerts@uclouvain.be, E-mail: hounkonnou@yahoo.fr, E-mail: norbert.hounkonnou@cipma.uac.bj, E-mail: habatwamweene@yahoo.com, E-mail: hmweene@unza.zm

    2009-12-04

    The ordinary Landau problem of a charged particle in a plane subjected to a perpendicular homogeneous and static magnetic field is reconsidered from different points of view. The role of phase space canonical transformations and their relation to a choice of gauge in the solution of the problem is addressed. The Landau problem is then extended to different contexts, in particular the singular situation of a purely linear potential term being added as an interaction, for which a complete purely algebraic solution is presented. This solution is then exploited to solve this same singular Landau problem in the half-plane, with as motivation the potential relevance of such a geometry for quantum Hall measurements in the presence of an electric field or a gravitational quantum well.

  9. Two-dimensional quantisation of the quasi-Landau hydrogenic spectrum

    International Nuclear Information System (INIS)

    Gallas, J.A.C.; O'Connell, R.F.

    1982-01-01

    Based on the two-dimensional WKB model, an equation is derived from which the non-relativistic quasi-Landau energy spectrum of hydrogen-like atoms may be easily obtained. In addition, the solution of radial equations in the WKB approximation and its relation with models recently used to fit experimental data are discussed. (author)

  10. Landau quantization and spin-momentum locking in topological Kondo insulators

    Directory of Open Access Journals (Sweden)

    P. Schlottmann

    2016-05-01

    Full Text Available SmB6 has been predicted to be a strong topological Kondo insulator and experimentally it has been confirmed that at low temperatures the electrical conductivity only takes place at the surfaces of the crystal. Quantum oscillations and ARPES measurements revealed several Dirac cones on the (001 and (101 surfaces of the crystal. We considered three types of surface Dirac cones with an additional parabolic dispersion and studied their Landau quantization and the expectation value of the spin of the electrons. The Landau quantization is quite similar in all three cases and would give rise to very similar de Haas-van Alphen oscillations. The spin-momentum locking, on the other hand, differs dramatically. Without the additional parabolic dispersion the spins are locked in the plane of the surface. The parabolic dispersion, however, produces a gradual canting of the spins out of the surface plane.

  11. Relativistic electron beam acceleration by cascading nonlinear Landau damping of electromagnetic waves in a plasma

    International Nuclear Information System (INIS)

    Sugaya, R.; Ue, A.; Maehara, T.; Sugawa, M.

    1996-01-01

    Acceleration and heating of a relativistic electron beam by cascading nonlinear Landau damping involving three or four intense electromagnetic waves in a plasma are studied theoretically based on kinetic wave equations and transport equations derived from relativistic Vlasov endash Maxwell equations. Three or four electromagnetic waves excite successively two or three nonresonant beat-wave-driven relativistic electron plasma waves with a phase velocity near the speed of light [v p =c(1-γ -2 p ) 1/2 , γ p =ω/ω pe ]. Three beat waves interact nonlinearly with the electron beam and accelerate it to a highly relativistic energy γ p m e c 2 more effectively than by the usual nonlinear Landau damping of two electromagnetic waves. It is proved that the electron beam can be accelerated to more highly relativistic energy in the plasma whose electron density decreases temporally with an appropriate rate because of the temporal increase of γ p . copyright 1996 American Institute of Physics

  12. Electron capture in very low energy collisions of multicharged ions with H and D in merged beams

    International Nuclear Information System (INIS)

    Havener, C.C.; Meyer, F.W.; Phaneuf, R.A.

    1991-01-01

    An ion-atom merged-beams technique is being used to measure total absolute electron-capture cross sections for multicharged ions in collisions with H (or D) in the energy range between 0.1 and 1000 eV/amu. Comparison between experiment and theory over such a large energy range constitutes a critical test for both experiment and theory. Total capture cross-section measurements for O 3+ H(D) and O 5+ + H(D) are presented and compared to state selective and differential cross section calculations. Landau-Zener calculations show that for O 5+ the sharp increase in the measured cross section below 1 eV/amu is partly due to trajectory effects arising from the ion-induced dipole interaction between the reactants. 20 refs., 8 figs

  13. Resummed memory kernels in generalized system-bath master equations

    International Nuclear Information System (INIS)

    Mavros, Michael G.; Van Voorhis, Troy

    2014-01-01

    Generalized master equations provide a concise formalism for studying reduced population dynamics. Usually, these master equations require a perturbative expansion of the memory kernels governing the dynamics; in order to prevent divergences, these expansions must be resummed. Resummation techniques of perturbation series are ubiquitous in physics, but they have not been readily studied for the time-dependent memory kernels used in generalized master equations. In this paper, we present a comparison of different resummation techniques for such memory kernels up to fourth order. We study specifically the spin-boson Hamiltonian as a model system bath Hamiltonian, treating the diabatic coupling between the two states as a perturbation. A novel derivation of the fourth-order memory kernel for the spin-boson problem is presented; then, the second- and fourth-order kernels are evaluated numerically for a variety of spin-boson parameter regimes. We find that resumming the kernels through fourth order using a Padé approximant results in divergent populations in the strong electronic coupling regime due to a singularity introduced by the nature of the resummation, and thus recommend a non-divergent exponential resummation (the “Landau-Zener resummation” of previous work). The inclusion of fourth-order effects in a Landau-Zener-resummed kernel is shown to improve both the dephasing rate and the obedience of detailed balance over simpler prescriptions like the non-interacting blip approximation, showing a relatively quick convergence on the exact answer. The results suggest that including higher-order contributions to the memory kernel of a generalized master equation and performing an appropriate resummation can provide a numerically-exact solution to system-bath dynamics for a general spectral density, opening the way to a new class of methods for treating system-bath dynamics

  14. Analysis of generalized negative binomial distributions attached to hyperbolic Landau levels

    International Nuclear Information System (INIS)

    Chhaiba, Hassan; Demni, Nizar; Mouayn, Zouhair

    2016-01-01

    To each hyperbolic Landau level of the Poincaré disc is attached a generalized negative binomial distribution. In this paper, we compute the moment generating function of this distribution and supply its atomic decomposition as a perturbation of the negative binomial distribution by a finitely supported measure. Using the Mandel parameter, we also discuss the nonclassical nature of the associated coherent states. Next, we derive a Lévy-Khintchine-type representation of its characteristic function when the latter does not vanish and deduce that it is quasi-infinitely divisible except for the lowest hyperbolic Landau level corresponding to the negative binomial distribution. By considering the total variation of the obtained quasi-Lévy measure, we introduce a new infinitely divisible distribution for which we derive the characteristic function.

  15. Analysis of generalized negative binomial distributions attached to hyperbolic Landau levels

    Energy Technology Data Exchange (ETDEWEB)

    Chhaiba, Hassan, E-mail: chhaiba.hassan@gmail.com [Department of Mathematics, Faculty of Sciences, Ibn Tofail University, P.O. Box 133, Kénitra (Morocco); Demni, Nizar, E-mail: nizar.demni@univ-rennes1.fr [IRMAR, Université de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex (France); Mouayn, Zouhair, E-mail: mouayn@fstbm.ac.ma [Department of Mathematics, Faculty of Sciences and Technics (M’Ghila), Sultan Moulay Slimane, P.O. Box 523, Béni Mellal (Morocco)

    2016-07-15

    To each hyperbolic Landau level of the Poincaré disc is attached a generalized negative binomial distribution. In this paper, we compute the moment generating function of this distribution and supply its atomic decomposition as a perturbation of the negative binomial distribution by a finitely supported measure. Using the Mandel parameter, we also discuss the nonclassical nature of the associated coherent states. Next, we derive a Lévy-Khintchine-type representation of its characteristic function when the latter does not vanish and deduce that it is quasi-infinitely divisible except for the lowest hyperbolic Landau level corresponding to the negative binomial distribution. By considering the total variation of the obtained quasi-Lévy measure, we introduce a new infinitely divisible distribution for which we derive the characteristic function.

  16. Boundary condition for Ginzburg-Landau theory of superconducting layers

    Czech Academy of Sciences Publication Activity Database

    Koláček, Jan; Lipavský, Pavel; Morawetz, K.; Brandt, E. H.

    2009-01-01

    Roč. 79, č. 17 (2009), 174510/1-174510/6 ISSN 1098-0121 R&D Projects: GA ČR GA202/08/0326; GA AV ČR IAA100100712 Institutional research plan: CEZ:AV0Z10100521 Keywords : superconductivity * Ginzburg-Landau theory Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.475, year: 2009

  17. Ginzburg-Landau vortices

    CERN Document Server

    Bethuel, Fabrice; Helein, Frederic

    2017-01-01

    This book is concerned with the study in two dimensions of stationary solutions of uɛ of a complex valued Ginzburg-Landau equation involving a small parameter ɛ. Such problems are related to questions occurring in physics, e.g., phase transition phenomena in superconductors and superfluids. The parameter ɛ has a dimension of a length which is usually small.  Thus, it is of great interest to study the asymptotics as ɛ tends to zero. One of the main results asserts that the limit u-star of minimizers uɛ exists. Moreover, u-star is smooth except at a finite number of points called defects or vortices in physics. The number of these defects is exactly the Brouwer degree – or winding number – of the boundary condition. Each singularity has degree one – or as physicists would say, vortices are quantized. The singularities have infinite energy, but after removing the core energy we are lead to a concept of finite renormalized energy.  The location of the singularities is completely determined by minimiz...

  18. Landau-Darrieus instability in an ablation front

    International Nuclear Information System (INIS)

    Piriz, A.R.; Portugues, R.F.

    2003-01-01

    An analytical model that shows the conditions for the existence of the Landau-Darrieus instability of an ablation front is presented. The model seems to agree with recently claimed simulation results [L. Masse et al., Proceedings of the 1st International Conference on Inertial Fusion Sciences and Applications (Elsevier, Paris, 2000), p. 220]. The model shows that the ablation front can be unstable in absence of gravity when the thermal flux is inhibited within the supercritical region of the corona

  19. Time-dependent Ginzburg-Landau equations for rotating and accelerating superconductors

    Czech Academy of Sciences Publication Activity Database

    Lipavský, P.; Bok, J.; Koláček, Jan

    2013-01-01

    Roč. 492, Sept (2013), 144-151 ISSN 0921-4534 R&D Projects: GA ČR(CZ) GAP204/11/0015 Institutional support: RVO:68378271 Keywords : superconductivity * Ginzburg-Landau theory * London field Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.110, year: 2013

  20. Effects of strain and quantum confinement in optically pumped nuclear magnetic resonance in GaAs: Interpretation guided by spin-dependent band structure calculations

    Science.gov (United States)

    Wood, R. M.; Saha, D.; McCarthy, L. A.; Tokarski, J. T.; Sanders, G. D.; Kuhns, P. L.; McGill, S. A.; Reyes, A. P.; Reno, J. L.; Stanton, C. J.; Bowers, C. R.

    2014-10-01

    A combined experimental-theoretical study of optically pumped nuclear magnetic resonance (OPNMR) has been performed in a GaAs /A l0.1G a0.9As quantum well film epoxy bonded to a Si substrate with thermally induced biaxial strain. The photon energy dependence of the Ga OPNMR signal was recorded at magnetic fields of 4.9 and 9.4 T at a temperature of 4.8-5.4 K. The data were compared to the nuclear spin polarization calculated from the electronic structure and differential absorption to spin-up and spin-down states of the electron conduction band using a modified k .p model based on the Pidgeon-Brown model. Comparison of theory with experiment facilitated the assignment of features in the OPNMR energy dependence to specific interband Landau level transitions. The results provide insight into how effects of strain and quantum confinement are manifested in optical nuclear polarization in semiconductors.

  1. Strong-coupling study of the Gribov ambiguity in lattice Landau gauge

    International Nuclear Information System (INIS)

    Maas, Axel; Pawlowski, Jan M.; Spielmann, Daniel; Sternbeck, Andre; Smekal, Lorenz von

    2010-01-01

    We study the strong-coupling limit β=0 of lattice SU(2) Landau gauge Yang-Mills theory. In this limit the lattice spacing is infinite, and thus all momenta in physical units are infinitesimally small. Hence, the infrared behavior can be assessed at sufficiently large lattice momenta. Our results show that at the lattice volumes used here, the Gribov ambiguity has an enormous effect on the ghost propagator in all dimensions. This underlines the severity of the Gribov problem and calls for refined studies also at finite β. In turn, the gluon propagator only mildly depends on the Gribov ambiguity. (orig.)

  2. Three-dimensional Ginzburg–Landau simulation of a vortex line ...

    Indian Academy of Sciences (India)

    pp. 295–304. Three-dimensional Ginzburg–Landau simulation of a vortex line displaced by a zigzag of pinning spheres. MAURO M DORIA1,∗, ANTONIO R de C ROMAGUERA1 and WELLES A M MORGADO2. 1Instituto de Fısica, Universidade Federal do Rio de Janeiro, C.P. 68528,. 21941-972, Rio de Janeiro RJ, Brazil.

  3. Calculation of the binding energy per nucleon and the quasi-particle interation in nuclear matter under consideration of relativistic medium effects

    International Nuclear Information System (INIS)

    Hippchen, T.

    1985-12-01

    In a first part, nuclear matter calculations have been performed in the Dirac-Brueckner approach using a) a nucleon-nucleon potential of one-boson-exchange (OBE) type and b) a more realistic interaction in which the fictitious σ-exchange of the OBE-model is replaced by explicit 2π- and πρ-exchange diagrams. Both potential models yield the correct empirical binding energy and saturation density. It turns out that the total sum of relativistic effects caused by the emplicit 2 π- and πρ-exchanges is comparable to those due to σ-exchange. In a second part, the nuclear quasiparticle interaction, i.e. the Landau parameters, have been calculated in the central (F), isospin (F'), spin (G) and spin-isospin (G') channel, in an analogous way. Compared to nonrelativistic calculations (including conventional medium corrections like Pauli and dispersion effects), a strong improvement has been found, especially in the F- and G-channel. Finally, the influence of A 1 -exchange is studied, in NN scattering and in nuclear matter. It turns out that, after a suitable and necessary readjustment of some meson parameters, its role is negligibly small. (orig.)

  4. Landau-Ginsburg models with N=2 supersymmetry as conventional conformal theories

    International Nuclear Information System (INIS)

    Marshakov, A.

    1990-01-01

    The conformal Landau-Ginsburg (LG) models are identified with the Toda-like two-dimensional field theories. At least in the N=2 supersymmetric case they possess a simple free-field representation, related to the Nicolai map. (orig.)

  5. Pulsar kicks with modified Urca and electrons in Landau levels

    International Nuclear Information System (INIS)

    Henley, Ernest M.; Johnson, Mikkel B.; Kisslinger, Leonard S.

    2007-01-01

    We derive the energy asymmetry given the protoneutron star during the time when the neutrino sphere is near the surface of the protoneutron star, using the modified Urca process. The electrons produced with the antineutrinos are in Landau levels due to the strong magnetic field, and this leads to asymmetry in the neutrino momentum, and a pulsar kick. The magnetic field must be strong enough for a large fraction of the electrons to be in the lowest Landau level; however, there is no direct dependence of our pulsar velocity on the strength of the magnetic field. Our main prediction is that the large pulsar kicks start at about 10 s and last for about 10 s, with the corresponding neutrinos correlated with the direction of the magnetic field. We predict a pulsar velocity of 1.03x10 -4 (T/10 10 K) 7 km/s, which reaches 1000 km/s if T≅10 11 K

  6. Fourier acceleration in lattice gauge theories. I. Landau gauge fixing

    International Nuclear Information System (INIS)

    Davies, C.T.H.; Batrouni, G.G.; Katz, G.R.; Kronfeld, A.S.; Lepage, G.P.; Wilson, K.G.; Rossi, P.; Svetitsky, B.

    1988-01-01

    Fourier acceleration is a useful technique which can be applied to many different numerical algorithms in order to alleviate the problem of critical slowing down. Here we describe its application to an optimization problem in the simulation of lattice gauge theories, that of gauge fixing a configuration of link fields to the Landau gauge (partial/sub μ/A/sup μ/ = 0). We find that a steepest-descents method of gauge fixing link fields at β = 5.8 on an 8 4 lattice can be made 5 times faster using Fourier acceleration. This factor will grow as the volume of the lattice is increased. We also discuss other gauges that are useful to lattice-gauge-theory simulations, among them one that is a combination of the axial and Landau gauges. This seems to be the optimal gauge to impose for the Fourier acceleration of two other important algorithms, the inversion of the fermion matrix and the updating of gauge field configurations

  7. STS Observations of Landau Levels at Graphite Surfaces

    OpenAIRE

    Matsui, T.; Kambara, H.; Niimi, Y.; Tagami, K.; Tsukada, M.; Fukuyama, Hiroshi

    2004-01-01

    Scanning tunneling spectroscopy measurements were made on surfaces of two different kinds of graphite samples, Kish graphite and highly oriented pyrolytic graphite (HOPG), at very low temperatures and in high magnetic fields. We observed a series of peaks in the tunnel spectra, which grow with increasing field, both at positive and negative bias voltages. These are associated with Landau quantization of the quasi two-dimensional electrons and holes in graphite in magnetic fields perpendicular...

  8. Gauges for the Ginzburg-Landau equations of superconductivity

    International Nuclear Information System (INIS)

    Fleckinger-Pelle, J.; Kaper, H.G.

    1995-01-01

    This note is concerned with gauge choices for the time-dependent Ginzburg-Landau equations of superconductivity. The requiations model the state of a superconducting sample in a magnetic field near the critical tempeature. Any two solutions related through a ''gauge transformation'' describe the same state and are physically indistinquishable. This ''gauge invariance'' can be exploited for analtyical and numerical purposes. A new gauge is proposed, which reduces the equations to a particularly attractive form

  9. From quantum to semiclassical kinetic equations: Nuclear matter estimates

    International Nuclear Information System (INIS)

    Galetti, D.; Mizrahi, S.S.; Nemes, M.C.; Toledo Piza, A.F.R. de

    1985-01-01

    Starting from the exact microscopic time evolution of the quantum one body density associated with a many fermion system semiclassical approximations are derived to it. In the limit where small momentum transfer two body collisions are dominant we get a Fokker-Planck equation and work out friction and diffusion tensors explicitly for nuclear matter. If arbitrary momentum transfers are considered a Boltzmann equation is derived and used to calculate the viscosity coefficient of nuclear matter. A derivation is given of the collision term used by Landau to describe the damping of zero sound waves at low temperature in Plasmas. Memory effects are essential for this. The damping of zero sound waves in nuclear matter is also calculated and the value so obtained associated with the bulk value of the damping of giant resonances in finite nuclei. The bulk value is estimated to be quite small indicating the importance of the nuclear surface for the damping. (Author) [pt

  10. Avaliação audiológica e eletrofisiológica da audição na síndrome de Landau-Kleffner Audiologic and electrophysiologic evaluation in Landau-Kleffner syndrome

    Directory of Open Access Journals (Sweden)

    Carla Gentile Matas

    2007-06-01

    Full Text Available OBJETIVO: Descrever os resultados obtidos nas avaliações audiológica e eletrofisiológica da audição, verificando a ocorrência de alterações auditivas periféricas e/ou centrais, de indivíduos com síndrome de Landau-Kleffner. MÉTODOS: Foram submetidos à avaliação audiológica (inspeção do meato acústico externo, medidas de imitância acústica, audiometrias tonal e vocal e eletrofisiológica da audição (potenciais evocados auditivos de curta, média e longa latência, quatro indivíduos com diagnóstico de síndrome de Landau-Kleffner, na faixa etária de nove a 19 anos, encaminhados ao Laboratório de Investigação Fonoaudiológica em Potenciais Evocados Auditivos do Curso de Fonoaudiologia da Universidade de São Paulo. RESULTADOS: Os resultados mostraram que 100% dos indivíduos apresentaram alteração em pelo menos uma das avaliações realizadas, sendo que houve uma maior ocorrência de alterações no potencial evocado auditivo de média latência (100% dos indivíduos apresentaram alterações. CONCLUSÕES: Observou-se uma grande ocorrência de alterações nos resultados das avaliações audiológicas e eletrofisiológicas da audição em indivíduos com síndrome de Landau-Kleffner. Enfatiza-se a importância da investigação da função auditiva destes indivíduos a fim de verificar possíveis relações entre os déficits da comunicação e alterações auditivas que possam estar presentes nessa população.PURPOSE: To describe the audiological and electrophysiological results of individuals with Landau-Kleffner syndrome, verifying the occurrence of peripheral and/or central auditory disorders. METHODS: Four individuals with Landau-Kleffner syndrome with ages ranging from nine to 19 years old, referred to the Auditory Evoked Potentials Laboratory of the Speech and Language Pathology and Audiology Course of the University of São Paulo, were submitted to audiologic (otoscopy, immitance measurements, pure tone and

  11. From Landau's hydrodynamical model to field theory model to field theory models of multiparticle production: a tribute to Peter

    International Nuclear Information System (INIS)

    Cooper, F.

    1996-01-01

    We review the assumptions and domain of applicability of Landau's Hydrodynamical Model. By considering two models of particle production, pair production from strong electric fields and particle production in the linear σ model, we demonstrate that many of Landau's ideas are verified in explicit field theory calculations

  12. Stability of zero-mode Landau levels in bilayer graphene against disorder in the presence of the trigonal warping

    International Nuclear Information System (INIS)

    Kawarabayashi, Tohru; Hasugai, Yasuhiro; Aoki, Hideo

    2013-01-01

    The stability of the zero-energy Landau levels in bilayer graphene against the chiral symmetric disorder is examined in the presence of the trigonal warping. Based on the tight-binding lattice model with a bond disorder correlated over several lattice constants, it is shown that among the four Landau levels per spin and per valley, two Landau levels exhibit the anomalous sharpness as in the absence of the trigonal warping, while the other two are broadened, yielding split peaks in the density of states. This can be attributed to the fact that the total chirality in each valley is ±2, which is protected topologically even in the presence of an intra-valley scattering due to disorder

  13. Landau level broadening without disorder, non-integer plateaus without interactions- an alternative model of the quantum Hall effect

    International Nuclear Information System (INIS)

    Kramer, T.

    2006-01-01

    I review some aspects of an alternative model of the quantum Hall effect, which is not based on the presence of disorder potentials. Instead, a quantization of the electronic drift current in the presence of crossed electric and magnetic fields is employed to construct a non-linear transport theory. Another important ingredient of the alternative theory is the coupling of the two-dimensional electron gas to the leads and the applied voltages. By working in a picture where the external voltages fix the chemical potential in the 2D subsystem, the experimentally observed linear relation between the voltage and the location of the quantum Hall plateaus finds an natural explanation. Also, the classical Hall effect emerges as a natural limit of the quantum Hall effect. For low temperatures (or high currents), a non-integer substructure splits higher Landau levels into sublevels. The appearance of substructure and non-integer plateaus in the resistivity is not linked to electron-electron interactions, but caused by the presence of a (linear) electric field. Some of the resulting fractions correspond exactly to half-integer plateaus. (Author)

  14. Quenching oscillating behaviors in fractional coupled Stuart-Landau oscillators

    Science.gov (United States)

    Sun, Zhongkui; Xiao, Rui; Yang, Xiaoli; Xu, Wei

    2018-03-01

    Oscillation quenching has been widely studied during the past several decades in fields ranging from natural sciences to engineering, but investigations have so far been restricted to oscillators with an integer-order derivative. Here, we report the first study of amplitude death (AD) in fractional coupled Stuart-Landau oscillators with partial and/or complete conjugate couplings to explore oscillation quenching patterns and dynamics. It has been found that the fractional-order derivative impacts the AD state crucially. The area of the AD state increases along with the decrease of the fractional-order derivative. Furthermore, by introducing and adjusting a limiting feedback factor in coupling links, the AD state can be well tamed in fractional coupled oscillators. Hence, it provides one an effective approach to analyze and control the oscillating behaviors in fractional coupled oscillators.

  15. Electron Landau damping of lower hybrid waves from a finite length antenna

    International Nuclear Information System (INIS)

    Brambilla, M.

    1977-01-01

    Launching and propagation of Lower Hybrid Waves to heat large plasmas by Electron Landau Damping is discussed. Conditions on the appropriate frequency and on the antenna location in the plasma density profile are derived

  16. Microscopic description of dissipative dynamics of a level-crossing transition

    Energy Technology Data Exchange (ETDEWEB)

    Scala, M.; Militello, B.; Messina, A. [Dipartimento di Fisica dell' Universita di Palermo, Via Archirafi 36, I-90123 Palermo (Italy); Vitanov, N. V. [Department of Physics, Sofia University, 5 James Bourchier Boulevard, BG-1164 Sofia (Bulgaria)

    2011-08-15

    We analyze the effect of a dissipative bosonic environment on the Landau-Zener-Stueckelberg-Majorana (LZSM) level crossing model by using a microscopic approach to derive the relevant master equation. For an environment at zero temperature and weak dissipation, our microscopic approach confirms the independence of the survival probability on the decay rate that has been predicted earlier by the simple phenomenological LZSM model. For strong decay the microscopic approach predicts a notable increase of the survival probability, which signals dynamical decoupling of the initial state. Unlike the phenomenological model, our approach makes it possible to study the dependence of the system dynamics on the temperature of the environment. In the limit of very high temperature we find that the dynamics is characterized by a very strong dynamical decoupling of the initial state--the temperature-induced quantum Zeno effect.

  17. Exact analytic solutions for Mikheyev-Smirnov-Wolfenstein level crossings

    International Nuclear Information System (INIS)

    Noetzold, D.

    1987-01-01

    An exact formula for the transition probability in level-crossing phenomena is derived for a general case, ranging from adiabatic to sudden crossings. This is done in the context of neutrino flavor oscillations for the Mikheyev-Smirnov-Wolfenstein (MSW) effect, where hitherto only numerical or approximate solutions were obtained. The matter density or level splitting is assumed to be governed by a hyperbolic-tangent function which, however, can change arbitrarily fast between two constant values. For example, in context of the MSW effect this furnishes a nice fit to the solar density determining the level crossing of solar neutrinos. In the quasiadiabatic limit the exact Landau-Zener factor can be read off, correcting some expressions obtained so far. Even in the opposite limit of a sudden level crossing a conversion is found, which can have far-reaching consequences for neutrino detection on Earth

  18. Magnetic vortices for a Ginzburg-Landau type energy with discontinuous constraint

    DEFF Research Database (Denmark)

    Kachmar, Ayman

    2010-01-01

    This paper is devoted to an analysis of vortex-nucleation for a Ginzburg-Landau functional with discontinuous constraint. This functional has been proposed as a model for vortex-pinning, and usually accounts for the energy resulting from the interface of two superconductors. The critical applied ...

  19. Fine structure of the lowest Landau level in suspended trilayer graphene

    NARCIS (Netherlands)

    van Elferen, H. J.; Veligura, A.; Tombros, N.; Kurganova, E. V.; van Wees, B. J.; Maan, J. C.; Zeitler, U.

    2013-01-01

    Magnetotransport experiments on ABC-stacked suspended trilayer graphene reveal a complete splitting of the 12-fold degenerated lowest Landau level, and, in particular, the opening of an exchange-driven gap at the charge neutrality point. A quantitative analysis of distinctness of the quantum Hall

  20. Scalar quanta in Fermi liquids: Zero sounds, instabilities, Bose condensation, and a metastable state in dilute nuclear matter

    Energy Technology Data Exchange (ETDEWEB)

    Kolomeitsev, E.E. [Matej Bel University, Banska Bystrica (Slovakia); Voskresensky, D.N. [National Research Nuclear University (MEPhI), Moscow (Russian Federation)

    2016-12-15

    The spectrum of bosonic scalar-mode excitations in a normal Fermi liquid with local scalar interaction is investigated for various values and momentum dependence of the scalar Landau parameter f{sub 0} in the particle-hole channel. For f{sub 0} > 0 the conditions are found when the phase velocity on the spectrum of zero sound acquires a minimum at non-zero momentum. For -1 < f{sub 0} < 0 there are only damped excitations, and for f{sub 0} < -1 the spectrum becomes unstable against the growth of scalar-mode excitations. An effective Lagrangian for the scalar excitation modes is derived after performing a bosonization procedure. We demonstrate that the instability may be tamed by the formation of a static Bose condensate of the scalar modes. The condensation may occur in a homogeneous or inhomogeneous state relying on the momentum dependence of the scalar Landau parameter. We show that in the isospin-symmetric nuclear matter there may appear a metastable state at subsaturation nuclear density owing to the condensate. Then we consider a possibility of the condensation of the zero-sound-like excitations in a state with a non-zero momentum in Fermi liquids moving with overcritical velocities, provided an appropriate momentum dependence of the Landau parameter f{sub 0}(k) > 0. We also argue that in peripheral heavy-ion collisions the Pomeranchuk instability may occur already for f{sub 0} > -1. (orig.)

  1. Partially filled Landau level at even denominators: A vortex metal with a Berry phase

    Science.gov (United States)

    You, Yizhi

    2018-04-01

    We develop a vortex metal theory for a partially filled Landau level at ν =1/2 n whose ground state contains a composite Fermi surface formed by the vortex of electrons. In the projected Landau-level limit, the composite Fermi surface contains a -π/n Berry phase. Such a fractional Berry phase is a consequence of Landau-level projection which produces the Girvin-MacDonald-Platzman [S. M. Girvin, A. H. MacDonald, and P. M. Platzman, Phys. Rev. B 33, 2481 (1986), 10.1103/PhysRevB.33.2481] guiding center algebra and embellishes an anomalous velocity to the equation of motion for the vortex metal. Further, we investigate a particle-hole symmetric bilayer system with ν1=1/2 n and ν2=1 -1/2 n at each layer, and demonstrate that the -π/n Berry phase on the composite Fermi surface leads to the suppression of 2 kf backscattering between the particle-hole partner bilayer, which could be a smoking gun to detect the fractional Berry phase. We also mention various instabilities and competing orders in such bilayer systems, including a Z4 n topological order phase driven by quantum criticality.

  2. Landau fluid models of collisionless magnetohydrodynamics

    International Nuclear Information System (INIS)

    Snyder, P.B.; Hammett, G.W.; Dorland, W.

    1997-01-01

    A closed set of fluid moment equations including models of kinetic Landau damping is developed which describes the evolution of collisionless plasmas in the magnetohydrodynamic parameter regime. The model is fully electromagnetic and describes the dynamics of both compressional and shear Alfven waves, as well as ion acoustic waves. The model allows for separate parallel and perpendicular pressures p parallel and p perpendicular , and, unlike previous models such as Chew-Goldberger-Low theory, correctly predicts the instability threshold for the mirror instability. Both a simple 3 + 1 moment model and a more accurate 4 + 2 moment model are developed, and both could be useful for numerical simulations of astrophysical and fusion plasmas

  3. Nonadiabatic ionic--covalent transitions. Exponential-linear model for the charge exchange and neutralization reactions Na+H arrow-right-left Na/sup +/+H/sup -/

    Energy Technology Data Exchange (ETDEWEB)

    Errea, L.F.; Mendez, L.; Mo, O.; Riera, A.

    1986-01-01

    A previous study of charge exchange processes taking place through ionic--covalent transitions is extended to the case of Na+H and Na/sup +/+H/sup -/ collisions. A five-state molecular expansion, with the inclusion of two-electron translation factors, is employed to calculate the charge exchange and neutralization cross sections. Transitions at the first two pseudocrossings between the energy curves, practically determine the cross sections in the energy range 0.16--5 keV amu/sup -1/. We also show that the widely used multichannel Landau--Zener theory is totally inadequate, to treat these transitions.

  4. Dynamics of a quantum phase transition

    International Nuclear Information System (INIS)

    Zurek, W.H.

    2005-01-01

    We present two approaches to the non-equilibrium dynamics of a quench-induced phase transition in quantum Ising model. First approach retraces steps of the standard calculation to thermodynamic second order phase transitions in the quantum setting. The second calculation is purely quantum, based on the Landau-Zener formula for transition probabilities in processes that involve avoided level crossings. We show that the two approaches yield compatible results for the scaling of the defect density with the quench rate. We exhibit similarities between them, and comment on the insights they give into dynamics of quantum phase transitions. (author)

  5. Inhomogeneous Weyl and Dirac Semimetals: Transport in Axial Magnetic Fields and Fermi Arc Surface States from Pseudo-Landau Levels

    Science.gov (United States)

    Grushin, Adolfo G.; Venderbos, Jörn W. F.; Vishwanath, Ashvin; Ilan, Roni

    2016-10-01

    Topological Dirac and Weyl semimetals have an energy spectrum that hosts Weyl nodes appearing in pairs of opposite chirality. Topological stability is ensured when the nodes are separated in momentum space and unique spectral and transport properties follow. In this work, we study the effect of a space-dependent Weyl node separation, which we interpret as an emergent background axial-vector potential, on the electromagnetic response and the energy spectrum of Weyl and Dirac semimetals. This situation can arise in the solid state either from inhomogeneous strain or nonuniform magnetization and can also be engineered in cold atomic systems. Using a semiclassical approach, we show that the resulting axial magnetic field B5 is observable through an enhancement of the conductivity as σ ˜B52 due to an underlying chiral pseudomagnetic effect. We then use two lattice models to analyze the effect of B5 on the spectral properties of topological semimetals. We describe the emergent pseudo-Landau-level structure for different spatial profiles of B5, revealing that (i) the celebrated surface states of Weyl semimetals, the Fermi arcs, can be reinterpreted as n =0 pseudo-Landau levels resulting from a B5 confined to the surface, (ii) as a consequence of position-momentum locking, a bulk B5 creates pseudo-Landau levels interpolating in real space between Fermi arcs at opposite surfaces, and (iii) there are equilibrium bound currents proportional to B5 that average to zero over the sample, which are the analogs of bound currents in magnetic materials. We conclude by discussing how our findings can be probed experimentally.

  6. Self-consistent Ginzburg-Landau theory for transport currents in superconductors

    DEFF Research Database (Denmark)

    Ögren, Magnus; Sørensen, Mads Peter; Pedersen, Niels Falsig

    2012-01-01

    We elaborate on boundary conditions for Ginzburg-Landau (GL) theory in the case of external currents. We implement a self-consistent theory within the finite element method (FEM) and present numerical results for a two-dimensional rectangular geometry. We emphasize that our approach can in princi...... in principle also be used for general geometries in three-dimensional superconductors....

  7. Charge Transfer in Collisions of S^4+ with He.

    Science.gov (United States)

    Wang, J. G.; Stancil, P. C.; Turner, A. R.; Cooper, D. L.; Schultz, D. R.; Rakovic, M. J.; Fritsch, W.; Zygelman, B.

    2001-05-01

    Charge transfer processes due to collisions of ground state S^4+ ions with atomic helium were investigated for energies between 0.1 meV/u and 10 MeV/u. Total and state-selective cross sections and rate coefficients were obtained utilizing the quantum-mechanical molecular-orbital close-coupling (MOCC), atomic-orbital close-coupling, classical trajectory Monte Carlo (CTMC), and continuum distorted wave methods. The MOCC calculations utilized ab initio adiabatic potentials and nonadiabatic radial coupling matrix elements obtained with the spin-coupled valence-bond approach. A number of variants of the CTMC approach were also explored. Previous data are limited to an earlier Landau-Zener calculation of the total rate coefficient for which our results are two orders of magnitude larger. An observed multichannel interference effect in the MOCC results will also be discussed.

  8. MD 2722: Investigation of Landau damping by means of BTF measurements

    CERN Document Server

    Tambasco, Claudia; Barranco Garcia, Javier; Boccardi, Andrea; Buffat, Xavier; Bruce, Roderik; Gasior, Marek; Hostettler, Michi; Lefevre, Thibaut; Levens, Tom; Louro Alves, Diogo Miguel; Metral, Elias; Pieloni, Tatiana; Pojer, Mirko; Salvachua Ferrando, Belen Maria; Solfaroli Camillocci, Matteo; CERN. Geneva. ATS Department

    2018-01-01

    Stability diagrams quantify the LHC stability thresholds due to the beam coupling impedance. Beam Transfer Function (BTF) measurements are a direct measurements of the stability diagram and therefore of the Landau damping of proton beams. Some coherent instabilities at the LHC are still not fully understood, especially when in the presence of beam-beam long range interactions at the end of the betatron squeeze. The beam-beam excited resonances can cause diffusive mechanisms and particle distribution changes that can lead to a different stability w.r.t. expectations for a Gaussian particle distribution. To investigate limitations of the models, a BTF system has been installed in the LHC in the 2015 in order to measure the Landau damping. During past MDs several configurations have been investigated: tune shifts and tune spread of the beams have been measured as a function of the octupole currents, tunes and beam-beam long range interactions. Some measurements artifacts were observed and mitigated, however the...

  9. ABOUT SOME APPROXIMATIONS TO THE CLOSED SET OF NOT TRIVIAL SOLUTIONS OF THE EQUATIONS OF GINZBURG - LANDAU

    Directory of Open Access Journals (Sweden)

    A. A. Fonarev

    2014-01-01

    Full Text Available Possibility of use of a projective iterative method for search of approximations to the closed set of not trivial generalised solutions of a boundary value problem for Ginzburg - Landau's equations of the phenomenological theory of superconduction is investigated. The projective iterative method combines a projective method and iterative process. The generalised solutions of a boundary value problem for Ginzburg - Landau's equations are critical points of a functional of a superconductor free energy.

  10. Magnetization plateaus of the frustrated Ising Shastry–Sutherland system: Wang–Landau simulation

    International Nuclear Information System (INIS)

    Lin, W.S.; Yang, T.H.; Wang, Y.; Qin, M.H.; Liu, J.-M.; Ren, Zhifeng

    2014-01-01

    The Wang–Landau algorithm is used to study the magnetic properties of the Ising model on the Shastry–Sutherland lattice in order to understand the interesting magnetization plateaus observed in TmB 4 . The simulated results demonstrate that the equilibrium state of the model produces only the 1/3 and 1/2 magnetization plateaus at low temperatures even when the random-exchange term or the long-range interactions are taken into account. This confirms our earlier conclusion (Huang et al., 2013) [20] that those fractional plateaus observed in experiments may be due to the magnetization dynamics. - Highlights: • The magnetic behaviors of TmB 4 are investigated using the Wang–Landau method. • The equilibrium state only produces the 1/3 and 1/2 magnetization plateaus. • Those fractional plateaus must arise from the non-equilibrium magnetization

  11. Magnetization plateaus of the frustrated Ising Shastry–Sutherland system: Wang–Landau simulation

    Energy Technology Data Exchange (ETDEWEB)

    Lin, W.S.; Yang, T.H.; Wang, Y. [Institute for Advanced Materials and Laboratory of Quantum Engineering and Quantum Materials, South China Normal University, Guangzhou 510006 (China); Qin, M.H., E-mail: qinmh@scnu.edu.cn [Institute for Advanced Materials and Laboratory of Quantum Engineering and Quantum Materials, South China Normal University, Guangzhou 510006 (China); Department of Physics and TcSUH, University of Houston, Houston, TX 77204 (United States); Liu, J.-M. [Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Ren, Zhifeng, E-mail: zren@uh.edu [Department of Physics and TcSUH, University of Houston, Houston, TX 77204 (United States)

    2014-07-04

    The Wang–Landau algorithm is used to study the magnetic properties of the Ising model on the Shastry–Sutherland lattice in order to understand the interesting magnetization plateaus observed in TmB{sub 4}. The simulated results demonstrate that the equilibrium state of the model produces only the 1/3 and 1/2 magnetization plateaus at low temperatures even when the random-exchange term or the long-range interactions are taken into account. This confirms our earlier conclusion (Huang et al., 2013) [20] that those fractional plateaus observed in experiments may be due to the magnetization dynamics. - Highlights: • The magnetic behaviors of TmB{sub 4} are investigated using the Wang–Landau method. • The equilibrium state only produces the 1/3 and 1/2 magnetization plateaus. • Those fractional plateaus must arise from the non-equilibrium magnetization.

  12. Nuclear chiral dynamics and thermodynamics

    Science.gov (United States)

    Holt, Jeremy W.; Kaiser, Norbert; Weise, Wolfram

    2013-11-01

    This presentation reviews an approach to nuclear many-body systems based on the spontaneously broken chiral symmetry of low-energy QCD. In the low-energy limit, for energies and momenta small compared to a characteristic symmetry breaking scale of order 1 GeV, QCD is realized as an effective field theory of Goldstone bosons (pions) coupled to heavy fermionic sources (nucleons). Nuclear forces at long and intermediate distance scales result from a systematic hierarchy of one- and two-pion exchange processes in combination with Pauli blocking effects in the nuclear medium. Short distance dynamics, not resolved at the wavelengths corresponding to typical nuclear Fermi momenta, are introduced as contact interactions between nucleons. Apart from a set of low-energy constants associated with these contact terms, the parameters of this theory are entirely determined by pion properties and low-energy pion-nucleon scattering observables. This framework (in-medium chiral perturbation theory) can provide a realistic description of both isospin-symmetric nuclear matter and neutron matter, with emphasis on the isospin-dependence determined by the underlying chiral NN interaction. The importance of three-body forces is emphasized, and the role of explicit Δ(1232)-isobar degrees of freedom is investigated in detail. Nuclear chiral thermodynamics is developed and a calculation of the nuclear phase diagram is performed. This includes a successful description of the first-order phase transition from a nuclear Fermi liquid to an interacting Fermi gas and the coexistence of these phases below a critical temperature Tc. Density functional methods for finite nuclei based on this approach are also discussed. Effective interactions, their density dependence and connections to Landau Fermi liquid theory are outlined. Finally, the density and temperature dependences of the chiral (quark) condensate are investigated.

  13. Size effect on the dielectric properties of BaTiO3 nanoceramics in a modified Ginsburg-Landau-Devonshire thermodynamic theory

    Science.gov (United States)

    Lin, Shan; Lü, Tianquan; Jin, Changqing; Wang, Xiaohui

    2006-10-01

    Grain size effects on the dielectric properties of BaTiO3 nanoceramics have been studied by using the modified Ginsburg-Landau-Devonshire (GLD) thermodynamic theory. Considering the existence of internal stresses, it is found that with decreasing grain size the transition temperature of cubic-tetragonal phase decreases, while those of tetragonal-orthorhombic and orthorhombic-rhombohedral phases increase. With further reducing grain size, our model predicts that the two ferroelectric structures of orthorhombic and tetragonal phases will become unstable and disappear at a critical size, leaving only one stable ferroelectric phase of rhombohedral structure. Consequently, a theoretical phase diagram of the transition temperature versus grain size is established wherein two triple points and a reentrance behavior are indicated. The results are compared with experimental data.

  14. Quantum transport in graphene in presence of strain-induced pseudo-Landau levels

    DEFF Research Database (Denmark)

    Settnes, Mikkel; Leconte, Nicolas; Barrios-Vargas, Jose E.

    2016-01-01

    We report on mesoscopic transport fingerprints in disordered graphene caused by strain-field induced pseudomagnetic Landau levels (pLLs). Efficient numerical real space calculations of the Kubo formula are performed for an ordered network of nanobubbles in graphene, creating pseudomagnetic fields...

  15. Nonlinear nuclear magnetic resonance in ferromagnets

    International Nuclear Information System (INIS)

    Nurgaliev, T.

    1988-01-01

    The properties of nonlinear nuclear magnetic resonance (NMR) have been studied theoretically by taking into account the interaction between NMR and FMR in the ferromagnets. The Landau-Lifshitz-Bloch equations, describing the electron and nuclear magnetization behaviour in ferromagnets are presented in an integral form for a weakly excited electronic system. The stationary solution of these equations has been analysed in the case of equal NMR and FMR frequencies: the criteria for the appearance of two stable dynamic states is found and the high-frequency magnetic susceptibility for these systems is investigated. 2 figs., 8 refs

  16. Electrostatic field in superconductors IV: theory of Ginzburg-Landau type

    Czech Academy of Sciences Publication Activity Database

    Lipavský, Pavel; Koláček, Jan

    2009-01-01

    Roč. 23, 20-21 (2009), s. 4505-4511 ISSN 0217-9792 R&D Projects: GA ČR GA202/04/0585; GA ČR GA202/05/0173; GA AV ČR IAA1010312 Institutional research plan: CEZ:AV0Z10100521 Keywords : superconductivity * Ginzburg-Landau theory Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.408, year: 2009

  17. Solutions without phase-slip for the Ginsburg-Landau equation

    International Nuclear Information System (INIS)

    Collet, P.; Eckmann, J.P.

    1992-01-01

    We consider the Ginsburg-Landau equation for a complex scalar field in one dimension and consider initial data which have two different stationary solutions as their limits in space as x→±∞. If these solutions are not very different, then we show that the initial data will evolve to a stationary solution by a 'phase melting' process which avoids 'phase slips,' i.e., which does not go through zero amplitude. (orig.)

  18. Transit-Time Damping, Landau Damping, and Perturbed Orbits

    Science.gov (United States)

    Simon, A.; Short, R. W.

    1997-11-01

    Transit-time damping(G.J. Morales and Y.C. Lee, Phys. Rev. Lett. 33), 1534 (1974).*^,*(P.A. Robinson, Phys. Fluids B 3), 545 (1991).** has traditionally been obtained by calculating the net energy gain of transiting electrons, of velocity v, to order E^2* in the amplitude of a localized electric field. This necessarily requires inclusion of the perturbed orbits in the equation of motion. A similar method has been used by others(D.R. Nicholson, Introduction to Plasma Theory) (Wiley, 1983).*^,*(E.M. Lifshitz and L.P. Pitaevskifi, Physical Kinetics) (Pergamon, 1981).** to obtain a ``physical'' picture of Landau damping in a nonlocalized field. The use of perturbed orbits seems odd since the original derivation of Landau (and that of Dawson) never went beyond a linear picture of the dynamics. We introduce a novel method that takes advantage of the time-reversal invariance of the Vlasov equation and requires only the unperturbed orbits to obtain the result. Obviously, there is much reduction in complexity. Application to finite slab geometry yields a simple expression for the damping rate. Equivalence to much more complicated results^2* is demonstrated. This method allows us to calculate damping in more complicated geometries and more complex electric fields, such as occur in SRS in filaments. See accompanying talk.(R.W. Short and A. Simon, this conference.) This work was supported by the U.S. DOE Office of Inertial Confinement Fusion under Co-op Agreement No. DE-FC03-92SF19460.

  19. Combined study of the gluon and ghost condensates μ2> and abccbcc> in Euclidean SU(2) Yang-Mills theory in the Landau gauge

    International Nuclear Information System (INIS)

    Capri, M.A.L.; Lemes, V.E.R.; Sobreiro, R.F.; Sorella, S.P.; Dudal, D.; Verschelde, H.; Gracey, J.A.

    2006-01-01

    The ghost condensate abc c b c c > is considered together with the gluon condensate μ 2 > in SU(2) Euclidean Yang-Mills theories quantized in the Landau gauge. The vacuum polarization ceases to be transverse due to the nonvanishing condensate abc c b c c >. The gluon propagator itself remains transverse. By polarization effects, this ghost condensate induces then a splitting in the gluon mass parameter, which is dynamically generated through μ 2 >. The obtained effective masses are real when μ 2 > is included in the analysis. In the absence of μ 2 >, the already known result that the ghost condensate induces effective tachyonic masses is recovered. At the one-loop level, we find that the effective diagonal mass becomes smaller than the off-diagonal one. This might serve as an indication for some kind of Abelian dominance in the Landau gauge, similar to what happens in the maximal Abelian gauge

  20. Asymptotic Bethe ansatz S-matrix and Landau-Lifshitz-type effective 2d actions

    International Nuclear Information System (INIS)

    Roiban, R; Tirziu, A; Tseytlin, A A

    2006-01-01

    Motivated by the desire to relate Bethe ansatz equations for anomalous dimensions found on the gauge-theory side of the AdS/CFT correspondence to superstring theory on AdS 5 x S 5 we explore a connection between the asymptotic S-matrix that enters the Bethe ansatz and an effective two-dimensional quantum field theory. The latter generalizes the standard 'non-relativistic' Landau-Lifshitz (LL) model describing low-energy modes of ferromagnetic Heisenberg spin chain and should be related to a limit of superstring effective action. We find the exact form of the quartic interaction terms in the generalized LL-type action whose quantum S-matrix matches the low-energy limit of the asymptotic S-matrix of the spin chain of Beisert, Dippel and Staudacher (BDS). This generalizes to all orders in the 't Hooft coupling λ an earlier computation of Klose and Zarembo of the S-matrix of the standard LL model. We also consider a generalization to the case when the spin-chain S-matrix contains an extra 'string' phase and determine the exact form of the LL 4-vertex corresponding to the low-energy limit of the ansatz of Arutyunov, Frolov and Staudacher (AFS). We explain the relation between the resulting 'non-relativistic' non-local action and the second-derivative string sigma model. We comment on modifications introduced by strong-coupling corrections to the AFS phase. We mostly discuss the SU(2) sector but also present generalizations to the SL(2) and SU(1|1) sectors, confirming universality of the dressing phase contribution by matching the low-energy limit of the AFS-type spin-chain S-matrix with tree-level string-theory S-matrix

  1. Fluid moments of the nonlinear Landau collision operator

    Energy Technology Data Exchange (ETDEWEB)

    Hirvijoki, E.; Pfefferlé, D. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Lingam, M.; Bhattacharjee, A. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544 (United States); Comisso, L. [Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544 (United States); Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Candy, J. [General Atomics, San Diego, California 92186 (United States)

    2016-08-15

    An important problem in plasma physics is the lack of an accurate and complete description of Coulomb collisions in associated fluid models. To shed light on the problem, this Letter introduces an integral identity involving the multivariate Hermite tensor polynomials and presents a method for computing exact expressions for the fluid moments of the nonlinear Landau collision operator. The proposed methodology provides a systematic and rigorous means of extending the validity of fluid models that have an underlying inverse-square force particle dynamics to arbitrary collisionality and flow.

  2. About Ginzburg-Landau, and a bit on others

    International Nuclear Information System (INIS)

    Maksimov, Evgenii G

    2011-01-01

    This note is a brief history of how the theory of Ginzburg and Landau came to be. Early publications on the macroscopic theory of superconductivity are reviewed in detail. Discussions that the two co-authors had with their colleagues and between themselves are described. The 1952 review by V L Ginzburg is discussed, in which a number of well-defined requirements on the yet-to-be-developed microscopic theory of superconductivity were formulated, constituting what J Bardeen called the 'Ginzburg energy gap model'. (from the history of physics)

  3. Nucleation of the lamellar phase from the disordered phase of the renormalized Landau-Brazovskii model

    Science.gov (United States)

    Carilli, Michael F.; Delaney, Kris T.; Fredrickson, Glenn H.

    2018-02-01

    Using the zero-temperature string method, we investigate nucleation of a stable lamellar phase from a metastable disordered phase of the renormalized Landau-Brazovskii model at parameters explicitly connected to those of an experimentally accessible diblock copolymer melt. We find anisotropic critical nuclei in qualitative agreement with previous experimental and analytic predictions; we also find good quantitative agreement with the predictions of a single-mode analysis. We conduct a thorough search for critical nuclei containing various predicted and experimentally observed defect structures. The predictions of the renormalized model are assessed by simulating the bare Landau-Brazovskii model with fluctuations. We find that the renormalized model makes reasonable predictions for several important quantities, including the order-disorder transition (ODT). However, the critical nucleus size depends sharply on proximity to the ODT, so even small errors in the ODT predicted by the renormalized model lead to large errors in the predicted critical nucleus size. We conclude that the renormalized model is a poor tool to study nucleation in the fluctuating Landau-Brazovskii model, and recommend that future studies work with the fluctuating bare model directly, using well-chosen collective variables to investigate kinetic pathways in the disorder → lamellar transition.

  4. Exact solutions of the one-dimensional generalized modified complex Ginzburg-Landau equation

    International Nuclear Information System (INIS)

    Yomba, Emmanuel; Kofane, Timoleon Crepin

    2003-01-01

    The one-dimensional (1D) generalized modified complex Ginzburg-Landau (MCGL) equation for the traveling wave systems is analytically studied. Exact solutions of this equation are obtained using a method which combines the Painleve test for integrability in the formalism of Weiss-Tabor-Carnevale and Hirota technique of bilinearization. We show that pulses, fronts, periodic unbounded waves, sources, sinks and solution as collision between two fronts are the important coherent structures that organize much of the dynamical properties of these traveling wave systems. The degeneracies of the 1D generalized MCGL equation are examined as well as several of their solutions. These degeneracies include two important equations: the 1D generalized modified Schroedinger equation and the 1D generalized real modified Ginzburg-Landau equation. We obtain that the one parameter family of traveling localized source solutions called 'Nozaki-Bekki holes' become a subfamily of the dark soliton solutions in the 1D generalized modified Schroedinger limit

  5. Enhanced atomic mobility due to low dose neutron irradiation as measured in a 30Ag at % Zn alloy by Zener relaxation methods

    International Nuclear Information System (INIS)

    Halbwachs, M.; Hillairet, J.; Gonzalez, H.; Cost, J.

    1975-01-01

    Mean atomic jump rates were measured during and after short-time neutron irradiations of a fcc Ag-30 at. percent Zn alloy by monitoring the rate of the Zener relaxation. Measurements made at 40 0 C immediately after rapid suppression of the flux showed significant enhancement of the atomic mobility for a flux of approximately 10 11 fast n/cm 2 .sec and an irradiation time of only 30 sec. The subsequent decrease of the atomic mobility to the thermal equilibrium value was studied and found to follow simple exponential decay. The results are discussed in terms of the nature and concentration of mobile defects created by cascades, the mechanism for defect annihilation and the concentration of sinks

  6. N=2 superconformal models, Landau-Ginsburg Hamiltonians and the ε expansion

    International Nuclear Information System (INIS)

    Howe, P.S.; West, P.C.

    1989-01-01

    The anomalous dimensions of a class of operators, operator product expansions and the central change, c, are calculated in a family of N=2 supersymmetric two-dimensional Landau-Ginsburg models. The results allow the identification of these theories with N=2 minimal superconformal models. A key role is placed by the N=2 non-renormalization theorem. (orig.)

  7. Statistical mechanics of low-dimensional Ginzburg-Landau fields. Some new results

    International Nuclear Information System (INIS)

    Barsan, V.

    1987-08-01

    The Ginzburg-Landau theory for low-dimensional systems is approached using the transfer matrix method. Analitical formulae for the thermodynamical quantities of interest are obtained in the one-dimensional case. An exact expression for the free energy of of a planar array of linear chains is deduced. A good agrement with numerical and experimental data is found.(authors)

  8. Modeling of superconductors based on the timedependent Ginsburg-Landau equations

    Science.gov (United States)

    Grishakov, K. S.; Degtyarenko, P. N.; Degtyarenko, N. N.; Elesin, V. F.; Kruglov, V. S.

    2009-11-01

    Results of modeling of superconductor magnetization process based on a numerical solution of the timedependent Ginsburg-Landau equations are presented. Methods of grid approximation of the equations and method of finite elements are used. Two-dimensional patterns of changes in the order parameter and supercurrent distribution in superconductors are calculated and visualized. The main results are in agreement with the well-known representations for type I and II superconductors.

  9. ENERGY DISSIPATION AND LANDAU DAMPING IN TWO- AND THREE-DIMENSIONAL PLASMA TURBULENCE

    Energy Technology Data Exchange (ETDEWEB)

    Li, Tak Chu; Howes, Gregory G. [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 (United States); Klein, Kristopher G. [Space Science Center, University of New Hampshire, Durham, NH 03824 (United States); TenBarge, Jason M. [IREAP, University of Maryland, College Park, MD 20742 (United States)

    2016-12-01

    Plasma turbulence is ubiquitous in space and astrophysical plasmas, playing an important role in plasma energization, but the physical mechanisms leading to dissipation of the turbulent energy remain to be definitively identified. Kinetic simulations in two dimensions (2D) have been extensively used to study the dissipation process. How the limitation to 2D affects energy dissipation remains unclear. This work provides a model of comparison between two- and three-dimensional (3D) plasma turbulence using gyrokinetic simulations; it also explores the dynamics of distribution functions during the dissipation process. It is found that both 2D and 3D nonlinear gyrokinetic simulations of a low-beta plasma generate electron velocity-space structures with the same characteristics as that of the linear Landau damping of Alfvén waves in a 3D linear simulation. The continual occurrence of the velocity-space structures throughout the turbulence simulations suggests that the action of Landau damping may be responsible for the turbulent energy transfer to electrons in both 2D and 3D, and makes possible the subsequent irreversible heating of the plasma through collisional smoothing of the velocity-space fluctuations. Although, in the 2D case where variation along the equilibrium magnetic field is absent, it may be expected that Landau damping is not possible, a common trigonometric factor appears in the 2D resonant denominator, leaving the resonance condition unchanged from the 3D case. The evolution of the 2D and 3D cases is qualitatively similar. However, quantitatively, the nonlinear energy cascade and subsequent dissipation is significantly slower in the 2D case.

  10. Geometry of (0,2) Landau-Ginzburg orbifolds

    International Nuclear Information System (INIS)

    Kawai, Toshiya; Mohri, Kenji

    1994-01-01

    Several aspects of (0,2) Landau-Ginzburg orbifolds are investigated. Especially the elliptic genera are computed in general and, for a class of models recently invented by Distler and Kachru, they are compared with the ones from (0,2) sigma models. Our formalism gives an easy way to calculate the generation numbers for lots of Distler-Kachru models even if they are based on singular Calabi-Yau spaces. We also make some general remarks on the Born-Oppenheimer calculation of the ground states elucidating its mathematical meaning in the untwisted sector. For Distler-Kachru models based on non-singular Calabi-Yau spaces we show that there exist ''residue'' type formulas of the elliptic genera as well. ((orig.))

  11. Scaling of the susceptibility vs. magnetic-field sweep rate in Fe8 molecular magnet

    Science.gov (United States)

    Jordi, M.; Hernandez-Mínguez, A.; Hernandez, J. M.; Tejada, J.; Stroobants, S.; Vanacken, J.; Moshchalkov, V. V.

    2004-12-01

    The dependence of the magnetization reversal on the sweep rate of the applied magnetic field has been studied for single crystals of Fe8 magnetic molecules. Our experiments have been conducted at temperatures below 1 K and sweep rates of the magnetic field between 103 T/s to 104 T/s. The systematic shift of the values of the magnetic field at which the magnetization reversal occurs, indicates that this reversal process is not governed by the Landau-Zener transition model. Our data can be explained in terms of the superradiance emission model proposed by Chudnovsky and Garanin (Phys. Rev. Lett. 89 (2002) 157201).

  12. Single-electron capture into Ar+ excited states in Ar2 + Na collision below 12 keV, 2

    International Nuclear Information System (INIS)

    Matsumoto, Atsushi; Tsurubuchi, Seiji; Okuno, Kazuhiko; Ohtani, Shunsuke; Iwai, Tsuruji.

    1979-08-01

    Excitation cross-sections are obtained for each term of the ArII nl-states (nl = 4p, 4p' and 4d) at 4 and 8 keV. The relative population distribution among the terms of a given nl-state can be interpreted in terms of statistics based on the building-up principle of molecule under radial coupling scheme. The relative population distribution among the multiplets in a given term is proportional to their statistical weight; spin-orbit recoupling at large internuclear separations is responsible for the population mechanism. The energy dependence of excitation cross-sections is discussed in connection with the Landau-Zener theory. (author)

  13. The role of spin-orbit coupling in the photolysis of methylcobalamin

    Energy Technology Data Exchange (ETDEWEB)

    Andruniów, Tadeusz [Department of Chemistry, Advanced Materials Engineering and Modelling Group, Wroclaw University of Technology, 50-370 Wroclaw (Poland); Lodowski, Piotr; Jaworska, Maria [Department of Theoretical Chemistry, Institute of Chemistry, University of Silesia, Szkolna 9, PL-40 006 Katowice (Poland); Garabato, Brady D. [Department of Chemistry, University of Louisville, 2320 South Brook Street, Louisville, Kentucky 40292 (United States); Kozlowski, Pawel M., E-mail: pawel@louisville.edu [Department of Chemistry, University of Louisville, 2320 South Brook Street, Louisville, Kentucky 40292 (United States); Department of Food Sciences, Medical University of Gdansk, Al. Gen. J. Hallera 107, 80-416 Gdansk (Poland)

    2016-03-28

    The photolysis of the methylcobalamin cofactor (MeCbl) in its base-off form was investigated by considering the extent of spin-orbit coupling (SOC). Triplet Co–C photodissociation pathways previously invoked at the density functional theory level using Landau-Zener theory were further validated with ab initio calculations that combine SOC based on multi-state second order perturbation theory. It was determined that SOC is feasible between singlet and triplet states at elongated Co–C distances, leading to photodissociation from the state having dominant σ(d{sub z}{sup 2}) character, by either direct coupling with the lowest singlet states or by crossing with SOC mixed triplets.

  14. Evidence for the existence of Gribov copies in Landau gauge lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Marinari, E.; Ricci, R. (Rome-2 Univ. (Italy). Dipt. di Fisica INFN, Rome (Italy)); Parrinello, C. (New York Univ., NY (USA). Physics Dept.)

    1991-09-16

    We unambiguously show the existence of Gribov copies in a pure SU(3) gauge lattice model, with Wilson action. We show that the usual steepest-descent algorithms used for implementing the lattice Landau gauge lead to ambiguities, which are related to the existence of Gribov copies in the model. (orig.).

  15. Variational principles for Ginzburg-Landau equation by He's semi-inverse method

    International Nuclear Information System (INIS)

    Liu, W.Y.; Yu, Y.J.; Chen, L.D.

    2007-01-01

    Via the semi-inverse method of establishing variational principles proposed by He, a generalized variational principle is established for Ginzburg-Landau equation. The present theory provides a quite straightforward tool to the search for various variational principles for physical problems. This paper aims at providing a more complete theoretical basis for applications using finite element and other direct variational methods

  16. A rigorous proof of the Landau-Peierls formula and much more

    DEFF Research Database (Denmark)

    Briet, Philippe; Cornean, Horia; Savoie, Baptiste

    2012-01-01

    We present a rigorous mathematical treatment of the zero-field orbital magnetic susceptibility of a non-interacting Bloch electron gas, at fixed temperature and density, for both metals and semiconductors/insulators. In particular, we obtain the Landau-Peierls formula in the low temperature and d...... and density limit as conjectured by Kjeldaas and Kohn (Phys Rev 105:806–813, 1957)....

  17. Unusual interlayer quantum transport behavior caused by the zeroth Landau level in YbMnBi2.

    Science.gov (United States)

    Liu, J Y; Hu, J; Graf, D; Zou, T; Zhu, M; Shi, Y; Che, S; Radmanesh, S M A; Lau, C N; Spinu, L; Cao, H B; Ke, X; Mao, Z Q

    2017-09-21

    Relativistic fermions in topological quantum materials are characterized by linear energy-momentum dispersion near band crossing points. Under magnetic fields, relativistic fermions acquire Berry phase of π in cyclotron motion, leading to a zeroth Landau level (LL) at the crossing point, a signature unique to relativistic fermions. Here we report the unusual interlayer quantum transport behavior resulting from the zeroth LL mode observed in the time reversal symmetry breaking type II Weyl semimetal YbMnBi 2 . The interlayer magnetoresistivity and Hall conductivity of this material are found to exhibit surprising angular dependences under high fields, which can be well fitted by a model, which considers the interlayer quantum tunneling transport of the zeroth LL's Weyl fermions. Our results shed light on the unusual role of zeroth LLl mode in transport.The transport behavior of the carriers residing in the lowest Landau level is hard to observe in most topological materials. Here, Liu et al. report a surprising angular dependence of the interlayer magnetoresistivity and Hall conductivity arising from the lowest Landau level under high magnetic field in type II Weyl semimetal YbMnBi 2 .

  18. Landau-Kleffner Syndrome: An Exploration of Parent Experience of the Diagnostic Process

    Science.gov (United States)

    Lemard-Reid, Daunette

    2014-01-01

    Landau-Kleffner syndrome (LKS) is a rare childhood disorder that is often misdiagnosed as autism or childhood psychosis because of overlapping symptom presentation. Favorable prognoses in LKS depend on early diagnosis and treatment. While much is known about the clinical basis for LKS diagnosis, little is known about parents' lived experience with…

  19. TDHF and fluid dynamics of nuclear collective motions

    International Nuclear Information System (INIS)

    Di Nardo, M.; Di Toro, M.; Giansiracusa, G.; Lombardo, U.; Russo, G.

    1983-01-01

    The nuclear fluid dynamical equations are derived from a mean field description of the nuclear dynamics. Simple approximate solutions, corresponding to generalized scaling modes, are worked out for rotations and vibrations, with the evaluation of inertial parameters and flow patterns. Giant resonances are shown to be quite well described within an irrotational ansatz, which is equivalent to a lowest multipoles (up to lsub(max)=2) distortion of the momentum distribution. The physical meaning of a higher order truncation of the TDHF-Fluid-Dynamics chain is finally discussed with its implication on low lying states and on some description of the Landau damping. (author)

  20. A Study of the Nonlinear Landau Damping in the Fourier Transformed VelocitySpace

    Czech Academy of Sciences Publication Activity Database

    Sedláček, Zdeněk

    2002-01-01

    Roč. 34, 1-2 (2002), s. 63-87 ISSN 0041-1450 Institutional research plan: CEZ:AV0Z2043910 Keywords : Landau damping * Van Kampen-Case eigenmodes * BGK modes * free streaming Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.453, year: 2002

  1. Domain Walls and Textured Vortices in a Two-Component Ginzburg-Landau Model

    DEFF Research Database (Denmark)

    Madsen, Søren Peder; Gaididei, Yu. B.; Christiansen, Peter Leth

    2005-01-01

    coupling between the two order parameters a ''textured vortex'' is found by analytical and numerical solution of the Ginzburg-Landau equations. With a Josephson type coupling between the two order parameters we find the system to split up in two domains separated by a domain wall, where the order parameter...... is depressed to zero....

  2. Multiphonon generation during photodissociation of slow Landau-Pekar polarons

    International Nuclear Information System (INIS)

    Myasnikov, E. N.; Myasnikova, A. E.; Mastropas, Z. P.

    2006-01-01

    The spectra of the low-temperature photodissociation (photoionization) of Landau-Pekar polarons are calculated using the theory of quantum-coherent states and a new method of variation with respect to the parameters of phonon vacuum deformation. It is shown that the final polaron states upon photodissociation may have different numbers of phonons produced in a single dissociation event and different momenta of charge carriers. The spectrum of optical absorption related to the photodissociation of polarons exhibits a superposition of bands corresponding to various numbers of phonons formed as a result of dissociation of a single polaron. Due to a large width of the energy region corresponding to the final states of charge carriers, the halfwidth of each band is on the order of the energy of polaron coupling and is much greater than the phonon energy. For this reason, the individual phonon bands exhibit strong overlap. The very broad and, probably, structureless band formed as a result of the superposition of all these components begins at an energy equal to the sum of the polaron coupling energy (E p ) and the phonon energy. This band has a maximum at a frequency of about 5.6E p /ℎ and a halfwidth on the order of 5.6E p /ℎ at a unit effective mass (m* = m e ) of band electrons. For an effective charge carrier mass within m* = (1-3)m e , the energy of the polaron band maximum can be estimated as 5E p with an error of about 10%, and the halfwidth falls within 3.4E p 1/2 p . The multiphonon character of this band is related to a decay of the phonon condensate after the escape of charge carrier from a polaron. Such polarons are likely to be observed in the spectra of complex metal oxides, including high-temperature superconductors. Examples of such polaron bands in the reported absorption and photoconductivity spectra of nonstoichiometric cuprates, manganites, nickelates, and titanates are presented. A theory of the formation of Landau-Pekar polarons with the

  3. Nuclear structure of s-d shell nuclei: what is new?

    International Nuclear Information System (INIS)

    Shanmugam, G.

    1995-01-01

    In this paper the shape evolution of the even-even s-d shell nuclei with temperature and spin is studied using Landau theory of phase transitions. The most important thermal fluctuations are incorporated in this study. The ground state pairing is also included in the calculations. Both the summation and Strutinsky methods are used for extracting the Landau constants. Both yield qualitatively similar results. To conclude, Landau theory of phase transitions can be effectively and economically used to study the structure of excited s-d shell nuclei. 10 refs., 2 tabs., 8 figs

  4. Cyclotron Acceleration of Relativistic Electrons through Landau Resonance with Obliquely Propagating Whistler Mode Chorus Emissions

    Science.gov (United States)

    Omura, Y.; Hsieh, Y. K.; Foster, J. C.; Erickson, P. J.; Kletzing, C.; Baker, D. N.

    2017-12-01

    A recent test particle simulation of obliquely propagating whistler mode wave-particle interaction [Hsieh and Omura, 2017] shows that the perpendicular wave electric field can play a significant role in trapping and accelerating relativistic electrons through Landau resonance. A further theoretical and numerical investigation verifies that there occurs nonlinear wave trapping of relativistic electrons by the nonlinear Lorentz force of the perpendicular wave magnetic field. An electron moving with a parallel velocity equal to the parallel phase velocity of an obliquely propagating wave basically see a stationary wave phase. Since the electron position is displaced from its gyrocenter by a distance ρ*sin(φ), where ρ is the gyroradius and φ is the gyrophase, the wave phase is modulated with the gyromotion, and the stationary wave fields as seen by the electron are expanded as series of Bessel functions Jn with phase variations n*φ. The J1 components of the wave electric and magnetic fields rotate in the right-hand direction with the gyrofrequency, and they can be in resonance with the electron undergoing the gyromotion, resulting in effective electron acceleration and pitch angle scattering. We have performed a subpacket analysis of chorus waveforms observed by the Van Allen Probes [Foster et al., 2017], and calculated the energy gain by the cyclotron acceleration through Landau resonance. We compare the efficiencies of accelerations by cyclotron and Landau resonances in typical events of rapid electron acceleration observed by the Van Allen Probes.References:[1] Hsieh, Y.-K., and Y. Omura (2017), Nonlinear dynamics of electrons interacting with oblique whistler mode chorus in the magnetosphere, J. Geophys. Res. Space Physics, 122, 675-694, doi:10.1002/2016JA023255.[2] Foster, J. C., P. J. Erickson, Y. Omura, D. N. Baker, C. A. Kletzing, and S. G. Claudepierre (2017), Van Allen Probes observations of prompt MeV radiation belt electron acceleration in nonlinear

  5. Derivation of Ginzburg-Landau theory for a one-dimensional system with contact interaction

    DEFF Research Database (Denmark)

    Frank, Rupert; Hanizl, Christian; Seiringer, Robert

    2013-01-01

    In a recent paper we give the first rigorous derivation of the celebrated Ginzburg-Landau (GL) theory, starting from the microscopic Bardeen-Cooper-Schrieffer (BCS) model. Here we present our results in the simplified case of a one-dimensional system of particles interacting via a delta-potential....

  6. Direct path from microscopic mechanics to Debye shielding, Landau damping and wave-particle interaction

    International Nuclear Information System (INIS)

    Escande, D F; Elskens, Yves; Doveil, F

    2015-01-01

    The derivation of Debye shielding and Landau damping from the N-body description of plasmas is performed directly by using Newton’s second law for the N-body system. This is done in a few steps with elementary calculations using standard tools of calculus and no probabilistic setting. Unexpectedly, Debye shielding is encountered together with Landau damping. This approach is shown to be justified in the one-dimensional case when the number of particles in a Debye sphere becomes large. The theory is extended to accommodate a correct description of trapping and chaos due to Langmuir waves. On top of their well-known production of collisional transport, the repulsive deflections of electrons are shown to produce shielding, in such a way that each particle is shielded by all other ones, while keeping in uninterrupted motion. (paper)

  7. Landau damping of dust acoustic waves in the presence of hybrid nonthermal nonextensive electrons

    Science.gov (United States)

    El-Taibany, W. F.; Zedan, N. A.; Taha, R. M.

    2018-06-01

    Based on the kinetic theory, Landau damping of dust acoustic waves (DAWs) propagating in a dusty plasma composed of hybrid nonthermal nonextensive distributed electrons, Maxwellian distributed ions and negatively charged dust grains is investigated using Vlasov-Poisson's equations. The characteristics of the DAWs Landau damping are discussed. It is found that the wave frequency increases by decreasing (increasing) the value of nonextensive (nonthermal) parameter, q (α ). It is recognized that α plays a significant role in observing damping or growing DAW oscillations. For small values of α , damping modes have been observed until reaching a certain value of α at which ω i vanishes, then a growing mode appears in the case of superextensive electrons. However, only damping DAW modes are observed in case of subextensive electrons. The present study is useful in the space situations where such distribution exists.

  8. Effects on a Landau-type system for a neutral particle with no permanent electric dipole moment subject to the Kratzer potential in a rotating frame.

    Science.gov (United States)

    Oliveira, Abinael B; Bakke, Knut

    2016-06-01

    The behaviour of a neutral particle (atom, molecule) with an induced electric dipole moment in a region with a uniform effective magnetic field under the influence of the Kratzer potential (Kratzer 1920 Z. Phys. 3 , 289-307. (doi:10.1007/BF01327754)), and rotating effects is analysed. It is shown that the degeneracy of the Landau-type levels is broken and the angular frequency of the system acquires a new contribution that stems from the rotation effects. Moreover, in the search for bound state solutions, it is shown that the possible values of this angular frequency of the system are determined by the quantum numbers associated with the radial modes and the angular momentum, the angular velocity of the rotating frame and by the parameters associated with the Kratzer potential.

  9. Gradient corrections to the time-dependent Ginzburg-Landau eqzation for anisotropic perturbations of quasiparticles

    Czech Academy of Sciences Publication Activity Database

    Lin, P.-J.; Lipavský, Pavel

    2008-01-01

    Roč. 77, č. 14 (2008), 144505/1-144505/16 ISSN 1098-0121 Institutional research plan: CEZ:AV0Z10100521 Keywords : non-equilibrium superconductivity * Ginzburg-Landau theory Subject RIV: BE - Theoretical Physics Impact factor: 3.322, year: 2008

  10. Landau fluid equations for electromagnetic and electrostatic fluctuations

    International Nuclear Information System (INIS)

    Hedrick, C.L.; Leboeuf, J.

    1992-01-01

    Closure relations are developed to allow approximate treatment of Landau damping and growth using fluid equations for both electrostatic and electromagnetic modes. The coefficients in these closure relations are related to approximations of the plasma dispersion function by ratios of polynomials. Thirteen different numerical sets of coefficients are given and explicitly related to previous fits to the plasma dispersion function. The application of the techniques presented in this paper is illustrated with the specific example of resistive g modes. Comparisons of full kinetic and approximate results are made for the solutions to the dispersion relation, radially resolved modes in sheared magnetic geometry, and the plasma dispersion function itself

  11. Design of an rf quadrupole for Landau damping

    Science.gov (United States)

    Papke, K.; Grudiev, A.

    2017-08-01

    The recently proposed superconducting quadrupole resonator for Landau damping in accelerators is subjected to a detailed design study. The optimization process of two different cavity types is presented following the requirements of the High Luminosity Large Hadron Collider (HL-LHC) with the main focus on quadrupolar strength, surface peak fields, and impedance. The lower order and higher order mode (LOM and HOM) spectrum of the optimized cavities is investigated and different approaches for their damping are proposed. On the basis of an example the first two higher order multipole errors are calculated. Likewise on this example the required rf power and optimal external quality factor for the input coupler is derived.

  12. Rapid characterization of microscopic two-level systems using Landau-Zener transitions in a superconducting qubit

    International Nuclear Information System (INIS)

    Tan, Xinsheng; Yu, Haifeng; Yu, Yang; Han, Siyuan

    2015-01-01

    We demonstrate a fast method to detect microscopic two-level systems in a superconducting phase qubit. By monitoring the population leak after sweeping the qubit bias flux, we are able to measure the two-level systems that are coupled with the qubit. Compared with the traditional method that detects two-level systems by energy spectroscopy, our method is faster and more sensitive. This method supplies a useful tool to investigate two-level systems in solid-state qubits

  13. Landau degeneracy and black hole entropy

    International Nuclear Information System (INIS)

    Costa, M.S.; Perry, M.J.

    1998-01-01

    We consider the supergravity solution describing a configuration of intersecting D4-branes with non-vanishing world-volume gauge fields. The entropy of such a black hole is calculated in terms of the D-branes quantised charges. The non-extreme solution is also considered and the corresponding thermodynamical quantities are calculated in terms of a D-brane/anti-D-brane system. To perform the quantum mechanical D-brane analysis we study open strings with their ends on branes with a magnetic condensate. Applying the results to our D-brane system we manage to have a perfect agreement between the D-brane entropy counting and the corresponding semi-classical result. The Landau degeneracy of the open string states describing the excitations of the D-brane system enters in a crucial way. We also derive the near-extreme results which agree with the semi-classical calculations. (orig.)

  14. Metriplectic Gyrokinetics and Discretization Methods for the Landau Collision Integral

    Science.gov (United States)

    Hirvijoki, Eero; Burby, Joshua W.; Kraus, Michael

    2017-10-01

    We present two important results for the kinetic theory and numerical simulation of warm plasmas: 1) We provide a metriplectic formulation of collisional electrostatic gyrokinetics that is fully consistent with the First and Second Laws of Thermodynamics. 2) We provide a metriplectic temporal and velocity-space discretization for the particle phase-space Landau collision integral that satisfies the conservation of energy, momentum, and particle densities to machine precision, as well as guarantees the existence of numerical H-theorem. The properties are demonstrated algebraically. These two result have important implications: 1) Numerical methods addressing the Vlasov-Maxwell-Landau system of equations, or its reduced gyrokinetic versions, should start from a metriplectic formulation to preserve the fundamental physical principles also at the discrete level. 2) The plasma physics community should search for a metriplectic reduction theory that would serve a similar purpose as the existing Lagrangian and Hamiltonian reduction theories do in gyrokinetics. The discovery of metriplectic formulation of collisional electrostatic gyrokinetics is strong evidence in favor of such theory and, if uncovered, the theory would be invaluable in constructing reduced plasma models. Supported by U.S. DOE Contract Nos. DE-AC02-09-CH11466 (EH) and DE-AC05-06OR23100 (JWB) and by European Union's Horizon 2020 research and innovation Grant No. 708124 (MK).

  15. Dynamics of perturbed wavetrain solutions to the Ginzburg-Landau equation

    International Nuclear Information System (INIS)

    Keefe, L.R.

    1984-01-01

    The bifurcation structure of even, spatially periodic solutions to the time-dependent Ginzburg-Landau equation is investigated analytically and numerically. A rich variety of behavior, including limit cycles, two-tori, period-doubling sequences, and strange attractors are found to exist in the phase space of the solutions constructed from spatial Fourier modes. Beginning with unstable perturbations to the spatially homogeneous Stokes solution, changes in solution behavior are examined as the perturbing wavenumber q is varied in the range 0.6 to 1.3. Solution bifurcations as q changes are often found to be associated with symmetry making or breaking changes in the structure of attractors in phase space. Two distinct mirror image attractors are found to coexist for many values of q. Chaotic motion is found for two ranges of q Lyapunov exponents of the solutions and the Lyapunov dimension of the corresponding attractors are calculated for the larger of these regions. Poincare sections of the attractors within this chaotic range are consistent with the dimension calculation and also reveal a bifurcation structure within the chaos which broadly resembles that found in one-dimensional quadratic maps. The integrability of the Ginzburg-Landau equation is also examined. It is demonstrated that the equation does not possess the Painleve property, except for a special case of the coefficients which corresponds to the integrable non-linear Schroedinger (NLS) equation

  16. Laser light triggers increased Raman amplification in the regime of nonlinear Landau damping

    International Nuclear Information System (INIS)

    Depierreux, S.; Goyon, C.; Masson-Laborde, P.E.; Yahia, V.; Loisel, G.; Labaune, C.

    2014-01-01

    Stimulated Raman backscattering (SRS) has many unwanted effects in megajoule-scale inertially confined fusion (ICF) plasmas. Moreover, attempts to harness SRS to amplify short laser pulses through backward Raman amplification have achieved limited success. In high temperature fusion plasmas, SRS usually occurs in a kinetic regime where the nonlinear response of the Langmuir wave to the laser drive and its host of complicating factors make it difficult to predict the degree of amplification that can be achieved under given experimental conditions. Here we present experimental evidence of reduced Landau damping with increasing Langmuir wave amplitude and determine its effects on Raman amplification. The threshold for trapping effects to influence the amplification is shown to be very low. Above threshold, the complex SRS dynamics results in increased amplification factors, which partly explains previous ICF experiments. These insights could aid the development of more efficient backward Raman amplification schemes in this regime. (authors)

  17. Boundary conditions in Ginsburg Landau theory and critical temperature of high-T superconductors

    Science.gov (United States)

    Lykov, A. N.

    2008-06-01

    New mixed boundary conditions to the Ginsburg-Landau equations are found to limit the critical temperature ( T) of high- T superconductors. Moreover, the value of the pseudogap in these superconductors can be explained by using the method. As a result, the macroscopic approach is proposed to increase T of cuprate superconductors.

  18. Landau-de Gennes theory of surface-enhanced ordering in smectic films.

    Science.gov (United States)

    Shalaginov, A N; Sullivan, D E

    2001-03-01

    A Landau theory for surface-enhanced ordering in smectic-A free-standing films is described, based on a generalization of de Gennes' model for a "presmectic" fluid confined between two walls. According to the theory, smectic ordering in free-standing films heated above the bulk smectic melting temperature is due to an intrinsic surface contribution rather than an external field. The theory yields a persistent finite-size effect, in that the film melting temperatures do not tend to the bulk transition temperature in the limit of infinite film thickness. It also predicts that a continuous transition from (N+1)- to N-layer films is impossible without an external field. The theory closely fits existing experimental data on layer-thinning transitions in compounds which exhibit a bulk smectic-A to nematic phase transition. Possible origins of the intrinsic surface contribution are discussed.

  19. Some Recent Progress on Quark Pairings in Dense Quark and Nuclear Matter

    International Nuclear Information System (INIS)

    Pang Jinyi; Wang Jincheng; Wang Qun

    2012-01-01

    In this review article we give a brief overview on some recent progress in quark pairings in dense quark/nuclear matter mostly developed in the past five years. We focus on following aspects in particular: the BCS-BEC crossover in the CSC phase, the baryon formation and dissociation in dense quark/nuclear matter, the Ginzburg-Landau theory for three-flavor dense matter with U A (1) anomaly, and the collective and Nambu-Goldstone modes for the spin-one CSC. (physics of elementary particles and fields)

  20. Efficient solution of 3D Ginzburg-Landau problem for mesoscopic superconductors

    International Nuclear Information System (INIS)

    Pereira, Paulo J; Moshchalkov, Victor V; Chibotaru, Liviu F

    2014-01-01

    The recently proposed approach for the solution of Ginzburg-Landau (GL) problem for 2D samples of arbitrary shape is, in this article, extended over 3D samples having the shape of (i) a prism with arbitrary base and (ii) a solid of revolution with arbitrary profile. Starting from the set of Laplace operator eigenfunctions of a 2D object, we construct an approximation to or the exact eigenfunctions of the Laplace operator of a 3D structure by applying an extrusion or revolution to these solutions. This set of functions is used as the basis to construct the solutions of the linearized GL equation. These solutions are then used as basis for the non-linear GL equation much like the famous LCAO method. To solve the non-linear equation, we used the Newton-Raphson method starting from the solution of the linear equation, i.e., the nucleation distribution of superconducting condensate. The vector potential approximations typically used in 2D cases, i.e., considering it as corresponding to applied constant field, are in the 3D case harder to justify. For that reason, we use a locally corrected Nystrom method to solve the second Ginzburg-Landau equation. The complete solution of GL problem is then achieved by solving self-consistently both equations

  1. A new maser effect in plasma turbulence

    International Nuclear Information System (INIS)

    Nambu, M.

    1983-01-01

    The present state of understanding of a new maser effect is reviewed. The new maser effect, the idea that the resonant electrons in a turbulent plasma can radiate amplified electromagnetic radiation, does not require population inversion of electrons. The new maser effect always coexists with Landau (or cyclotron) damping; thus it is a fundamental effect in plasma turbulence. In nuclear fusion, magnetic confinement will be at a disadvantage due to the enhanced radiation losses in the long wave length region, while inertial confinement will be improved by the laser effect in the X-ray region. (author)

  2. The Quasi-Electron Shell Structure of the Fractional Quantum Hall Effect

    Science.gov (United States)

    Haxton, Wick; Haxton, Daniel

    2015-04-01

    The fractional quantum Hall effect (FQHE) formulated on a sphere resembles the nuclear shell model, with the desired translationally invariant states having total angular momentum zero. This property was exploited by Ginocchio and Haxton (GH) to derive a new set of scalar operators and a first-Landau-level representation of the full set of hierarchy states (fillings 1/3, 2/5, 3/7, etc.), with overlaps identical to those of Jain, who used unphysical higher Landau levels excitations followed by numerical projection. We demonstrate that the GH operators produce an appealing description of the FQHE as shells filled by non-interacting quasi-electrons, or composite fermions. These are explicitly constructed, and their planar forms are also found. The evolution of the shells and their quasi-electrons is quite unusual. The connections with electron correlations and Laughlin's variational arguments are described. We discuss how ``new states'' found experimentally at fillings such as 4/11 and 5/13 fit into this scheme. Work support in part by the US DOE Offices of Nuclear Physics and Basic Energy Sciences.

  3. Design of an rf quadrupole for Landau damping

    Directory of Open Access Journals (Sweden)

    K. Papke

    2017-08-01

    Full Text Available The recently proposed superconducting quadrupole resonator for Landau damping in accelerators is subjected to a detailed design study. The optimization process of two different cavity types is presented following the requirements of the High Luminosity Large Hadron Collider (HL-LHC with the main focus on quadrupolar strength, surface peak fields, and impedance. The lower order and higher order mode (LOM and HOM spectrum of the optimized cavities is investigated and different approaches for their damping are proposed. On the basis of an example the first two higher order multipole errors are calculated. Likewise on this example the required rf power and optimal external quality factor for the input coupler is derived.

  4. The infrared behaviour of the running coupling in Landau gauge QCD

    International Nuclear Information System (INIS)

    Alkofer, R.; Fischer, C.S.; Smekal, L. von.

    2002-01-01

    Approximate solutions for the gluon and ghost propagators as well as the running coupling in Landau gauge Yang-Mills theories are presented. These propagators obtained from the corresponding Dyson-Schwinger equations are in remarkable agreement with those of recent lattice calculations. The resulting running coupling possesses an infrared fixed point, α s (0) = 8.92/N for all gauge SU(N). Above one GeV the running coupling rapidly approaches its perturbative form (Authors)

  5. Nuclear dynamics with the (finite range) Gogny force: flow effects

    International Nuclear Information System (INIS)

    Sebille, F.; Royer, G.; Schuck, P.; Gregoire, C.

    1988-01-01

    We introduce for the first time the effective finite range interaction of Gogny in the semi-classical description of heavy ion reactions based on the Landau-Vlasov equation. The characteristics of the flow for heavy ion collisions are studied as functions of the incident energy, the impact parameter and the mass number. The momentum dependence in the mean field together with the non linearities in the collision kernel decrease the flow in contradiction with other calculations; the origins of this discrepancy are studied in details

  6. Boundary conditions in Ginsburg-Landau theory and critical temperature of high-Tc superconductors

    International Nuclear Information System (INIS)

    Lykov, A.N.

    2008-01-01

    New mixed boundary conditions to the Ginsburg-Landau equations are found to limit the critical temperature (T c ) of high-T c superconductors. Moreover, the value of the pseudogap in these superconductors can be explained by using the method. As a result, the macroscopic approach is proposed to increase T c of cuprate superconductors

  7. A Fokker-Planck-Landau collision equation solver on two-dimensional velocity grid and its application to particle-in-cell simulation

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, E. S.; Chang, C. S., E-mail: cschang@pppl.gov [Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); Korea Advanced Institute of Science and Technology, Yuseong-gu, DaeJeon 305-701 (Korea, Republic of)

    2014-03-15

    An approximate two-dimensional solver of the nonlinear Fokker-Planck-Landau collision operator has been developed using the assumption that the particle probability distribution function is independent of gyroangle in the limit of strong magnetic field. The isotropic one-dimensional scheme developed for nonlinear Fokker-Planck-Landau equation by Buet and Cordier [J. Comput. Phys. 179, 43 (2002)] and for linear Fokker-Planck-Landau equation by Chang and Cooper [J. Comput. Phys. 6, 1 (1970)] have been modified and extended to two-dimensional nonlinear equation. In addition, a method is suggested to apply the new velocity-grid based collision solver to Lagrangian particle-in-cell simulation by adjusting the weights of marker particles and is applied to a five dimensional particle-in-cell code to calculate the neoclassical ion thermal conductivity in a tokamak plasma. Error verifications show practical aspects of the present scheme for both grid-based and particle-based kinetic codes.

  8. Laser-induced charge transfer in the CH6+ quasimolecule

    International Nuclear Information System (INIS)

    Errea, L.F.; Mendez, L.; Riera, A.

    1985-01-01

    The charge transfer cross section is calculated for C 6+ +CH(1s) collisions, through photon assisted 5gsigma--6hsigma, 5gsigma--4fsigma, 5gsigma--4fπ, and 5gsigma--4dsigma transitions. The theory developed by Copeland and Tang, and ourselves, is employed, and the validity of the approximations used is tested. The four processes considered have widely different characteristics with regards to the laser wavelength needed, the collision dynamics and the applicability of back-of-the-envelope estimates based on the Landau--Zener approximation. We point out the relevance of those processes to the impurity diagnostics of magnetically confined fusion plasmas and to the development of short wavelength lasers

  9. Laser-induced charge exchange in ion-atom collisions

    International Nuclear Information System (INIS)

    Riera, A.

    1986-01-01

    The theory of laser-induced charge transfer (LICT) in ion-atom collisions is presented for the range of impact energies in which a quasimolecular description is appropriate. For each relative orientation of the AC field, LICT cross sections can be obtained with trivial modifications of standard programs. Simpler, perturbative expressions for the orientation-averaged cross sections are accurate for I v -1 6 W s cm -3 , and the analytical Landau-Zener perturbative expression often provides good estimates for these cross sections. The practical advantages of the dressed state formalism as an alternative approach are critically examined, and the general characteristics of LICT cross sections in multicharged ion-atom collisions are shown with the help of an example. (Auth.)

  10. Laser-induced charge transfer in the CH/sup 6 +/ quasimolecule

    Energy Technology Data Exchange (ETDEWEB)

    Errea, L.F.; Mendez, L.; Riera, A.

    1985-05-15

    The charge transfer cross section is calculated for C/sup 6 +/+CH(1s) collisions, through photon assisted 5gsigma--6hsigma, 5gsigma--4fsigma, 5gsigma--4f..pi.., and 5gsigma--4dsigma transitions. The theory developed by Copeland and Tang, and ourselves, is employed, and the validity of the approximations used is tested. The four processes considered have widely different characteristics with regards to the laser wavelength needed, the collision dynamics and the applicability of back-of-the-envelope estimates based on the Landau--Zener approximation. We point out the relevance of those processes to the impurity diagnostics of magnetically confined fusion plasmas and to the development of short wavelength lasers.

  11. Dromion-like structures and stability analysis in the variable coefficients complex Ginzburg–Landau equation

    International Nuclear Information System (INIS)

    Wong, Pring; Pang, Li-Hui; Huang, Long-Gang; Li, Yan-Qing; Lei, Ming; Liu, Wen-Jun

    2015-01-01

    The study of the complex Ginzburg–Landau equation, which can describe the fiber laser system, is of significance for ultra-fast laser. In this paper, dromion-like structures for the complex Ginzburg–Landau equation are considered due to their abundant nonlinear dynamics. Via the modified Hirota method and simplified assumption, the analytic dromion-like solution is obtained. The partial asymmetry of structure is particularly discussed, which arises from asymmetry of nonlinear and dispersion terms. Furthermore, the stability of dromion-like structures is analyzed. Oscillation structure emerges to exhibit strong interference when the dispersion loss is perturbed. Through the appropriate modulation of modified exponent parameter, the oscillation structure is transformed into two dromion-like structures. It indicates that the dromion-like structure is unstable, and the coherence intensity is affected by the modified exponent parameter. Results in this paper may be useful in accounting for some nonlinear phenomena in fiber laser systems, and understanding the essential role of modified Hirota method

  12. Wang-Landau Reaction Ensemble Method: Simulation of Weak Polyelectrolytes and General Acid-Base Reactions.

    Science.gov (United States)

    Landsgesell, Jonas; Holm, Christian; Smiatek, Jens

    2017-02-14

    We present a novel method for the study of weak polyelectrolytes and general acid-base reactions in molecular dynamics and Monte Carlo simulations. The approach combines the advantages of the reaction ensemble and the Wang-Landau sampling method. Deprotonation and protonation reactions are simulated explicitly with the help of the reaction ensemble method, while the accurate sampling of the corresponding phase space is achieved by the Wang-Landau approach. The combination of both techniques provides a sufficient statistical accuracy such that meaningful estimates for the density of states and the partition sum can be obtained. With regard to these estimates, several thermodynamic observables like the heat capacity or reaction free energies can be calculated. We demonstrate that the computation times for the calculation of titration curves with a high statistical accuracy can be significantly decreased when compared to the original reaction ensemble method. The applicability of our approach is validated by the study of weak polyelectrolytes and their thermodynamic properties.

  13. Improving nuclear regulatory effectiveness

    International Nuclear Information System (INIS)

    2001-01-01

    Ensuring that nuclear installations are operated and maintained in such a way that their impact on public health and safety is as low as reasonably practicable has been and will continue to be the cornerstone of nuclear regulation. In the past, nuclear incidents provided the main impetus for regulatory change. Today, economic factors, deregulation, technological advancements, government oversight and the general requirements for openness and accountability are leading regulatory bodies to review their effectiveness. In addition, seeking to enhance the present level of nuclear safety by continuously improving the effectiveness of regulatory bodies is seen as one of the ways to strengthen public confidence in the regulatory systems. This report covers the basic concepts underlying nuclear regulatory effectiveness, advances being made and future requirements. The intended audience is primarily nuclear safety regulators, but government authorities, nuclear power plant operators and the general public may also be interested. (author)

  14. Pattern selection and spatio-temporal transition to chaos in Ginzburg-Landau equation

    Energy Technology Data Exchange (ETDEWEB)

    Nozaki, K; Bekki, N

    1983-07-01

    It is shown that a modulationally unstable pattern is selected and propagates into an initially unstable motionless state in the 1-D generalized Ginzburg-Landau equation. A further spatio-temporal transition occurs with a sharp interface from the selected unstable pattern to a stabilized pattern or a chaotic state. The distinct transition makes a coherent structure to coexist with a chaotic state. 12 refs., 4 figs.

  15. Homotopy classification of minimizers of the Ginzburg-Landau energy and the existence of permanent currents

    International Nuclear Information System (INIS)

    Rubinstein, J.

    1996-01-01

    Our objective is to explain the phenomenon of permanent currents within the context of the Ginzburg-Landau model for superconductors. Using variational techniques we make a connection between the formation of permanent currents and the topology of the superconducting sample. (orig.)

  16. Transversal expansion study in the Landau hydrodynamic

    International Nuclear Information System (INIS)

    Pottag, F.W.

    1984-01-01

    The system of equations in the frame of Landau's hydrodynamical model for multiparticle production at high energies is studied. Taking as a first approximation the one-dimensional exact due to Khalatnikov, and a special set of curvilinear coordinates, the radial part is separated from the longitudinal one in the equations of motion, and a system of partial differential equations (non-linear, hyperbolic) is obtained for the radial part. These equations are solved numerically by the method of caracteristics. The hydrodynamical variables are obtained over all the three-dimensional-flow region as well as its variation with the mass of the initially expanding system. Both, the transverse rapidity distribution of the fluid and the inclusive particle distribution at 90 0 in the center of mass system, are calculated. The last one is compared with recent experimental data. (author) [pt

  17. Hamiltonian formalism of Whitham-type hierarchies and topological Landau-Ginsburg models

    International Nuclear Information System (INIS)

    Dubrovin, B.A.

    1992-01-01

    We show that the bi-hamiltonian structure of the averaged Gelfand-Dikii hierarchy is involved in the Landau-Ginsburg topological models (for A n -Series): The Casimirs for the first P.B. give the correct coupling parameters for the perturbed topological minimal model; the correspondence {coupling parameters}→{primary fields} is determined by the second P.B. The partition function (at the tree level) and the chiral algebra for LG minimal models are calculated for any genus g. (orig.)

  18. Spectrum of the linearized operator for the Ginzburg-Landau equation

    Directory of Open Access Journals (Sweden)

    Tai-Chia Lin

    2000-06-01

    Full Text Available We study the spectrum of the linearized operator for the Ginzburg-Landau equation about a symmetric vortex solution with degree one. We show that the smallest eigenvalue of the linearized operator has multiplicity two, and then we describe its behavior as a small parameter approaches zero. We also find a positive lower bound for all the other eigenvalues, and find estimates of the first eigenfunction. Then using these results, we give partial results on the dynamics of vortices in the nonlinear heat and Schrodinger equations.

  19. Collisional width of giant resonances and interplay with Landau damping

    International Nuclear Information System (INIS)

    Bonasera, A.; Burgio, G.F.; Di Toro, M.; Wolter, H.H.

    1989-01-01

    We present a semiclassical method to calculate the widths of giant resonances. We solve a mean-field kinetic equation (Vlasov equation) with collision terms treated within the relaxation time approximation to construct a damped strength distribution for collective motions. The relaxation time is evaluated from the time evolution of distortions in the nucleon momentum distribution using a test-particle approach. The importance of an energy dependent nucleon-nucleon cross section is stressed. Results are shown for isoscalar giant quadrupole and octupole motions. A quite important interplay between self-consistent (Landau) and collisional damping is revealed

  20. Macroscopic dynamics of thermal nuclear excitations

    International Nuclear Information System (INIS)

    Bastrukov, S.I.; Deak, F.; Kiss, A.; Seres, Z.

    1989-11-01

    The concept of kinetic temperature as a local dynamical variable of thermal nuclear collective motion is formulated using long-mean-free-path approach based on the Landau-Vlasov kinetic equation. In the Fermi drop model the thermal fluid dynamics of the spherical nucleus is analyzed. It is shown that in a compressible Fermi liquid the temperature pulses propagate in the form of spherical wave in phase with the acoustic wave. The thermal and compressional excitations are caused by the isotropic harmonic oscillations of the Fermi sphere in momentum space. (author) 25 refs.; 2 figs

  1. Ginsburg-Landau equation around the superconductor-insulator transition

    International Nuclear Information System (INIS)

    Ng, T.K.

    1991-01-01

    Based on the scaling theory of localization, we construct a Ginsburg-Landau (GL) equation for superconductors in an arbitrary strength of disordered potential. Using this GL equation, we reexamine the criteria for the superconductor-insulator transition and find that the transition to a localized superconductor can happen on both sides of the (normal) metal-insulator transition, in contrast to a previous prediction by Ma and Lee [Phys. Rev. B 32, 5658 (1985)] that the transition can only be on the insulator side. Furthermore, by comparing our theory with a recent scaling theory of dirty bosons by Fisher et al. [Phys. Rev. Lett. 64, 587 (1990)], we conclude that nontrivial crossover behavior in transport properties may occur in the vicinity of the superconductor-insulator transition

  2. Molecular orientational re-ordering and the transformation of a Landau second order phase transition to first order in a nematic liquid crystal

    International Nuclear Information System (INIS)

    Ponce, T.C.

    1988-08-01

    We consider the nature of the nematic to isotropic phase transition in terms of the molecular orientational re-ordering, expressed by the variation of the order parameter, s, in the light of Landau's theory of second order phase transition. Then, we show how the de Gennes modification to the Landau thermodynamic potential converts the transition to first order which is in better agreement with the experimental observations. (author). 9 refs, 2 figs, 1 tab

  3. International forum on nuclear and biological decommissioning: Management of global security threats

    International Nuclear Information System (INIS)

    Aslanian, G.; Kouzminov, V.; Martellini, M.; Santesso, R.

    1998-01-01

    The Forum on Nuclear and Biological Decommissioning: Management of Global Security Threats was organized by the Landau Network-Centro Volta (LNCV) with the support of the UNESCO Venice Office, the Italian Ministry of Foreign Affairs, the Italian National Board for Alternative Energy Sources (ENEA), the Lombardy Region and the Municipality of Como. Subjects dealt with at the conference included the reconversion of nuclear and biological military equipment produced in the 50 years of the Cold War period and the effects of radio contamination on the environment and on human life. This conference was the most recent of a number of initiatives on reconversion organized in collaboration with the UNESCO Venice Office. The issues dealt with at the conference will be among the subjects for discussion at the UNESCO International School Science for Peace, which will be set up at the 'A. Volta' Center for Scientific Culture

  4. Macroscopically constrained Wang-Landau method for systems with multiple order parameters and its application to drawing complex phase diagrams

    Science.gov (United States)

    Chan, C. H.; Brown, G.; Rikvold, P. A.

    2017-05-01

    A generalized approach to Wang-Landau simulations, macroscopically constrained Wang-Landau, is proposed to simulate the density of states of a system with multiple macroscopic order parameters. The method breaks a multidimensional random-walk process in phase space into many separate, one-dimensional random-walk processes in well-defined subspaces. Each of these random walks is constrained to a different set of values of the macroscopic order parameters. When the multivariable density of states is obtained for one set of values of fieldlike model parameters, the density of states for any other values of these parameters can be obtained by a simple transformation of the total system energy. All thermodynamic quantities of the system can then be rapidly calculated at any point in the phase diagram. We demonstrate how to use the multivariable density of states to draw the phase diagram, as well as order-parameter probability distributions at specific phase points, for a model spin-crossover material: an antiferromagnetic Ising model with ferromagnetic long-range interactions. The fieldlike parameters in this model are an effective magnetic field and the strength of the long-range interaction.

  5. Vacuum Bloch-Siegert shift in Landau polaritons with ultra-high cooperativity

    Science.gov (United States)

    Li, Xinwei; Bamba, Motoaki; Zhang, Qi; Fallahi, Saeed; Gardner, Geoff C.; Gao, Weilu; Lou, Minhan; Yoshioka, Katsumasa; Manfra, Michael J.; Kono, Junichiro

    2018-06-01

    A two-level system resonantly interacting with an a.c. magnetic or electric field constitutes the physical basis of diverse phenomena and technologies. However, Schrödinger's equation for this seemingly simple system can be solved exactly only under the rotating-wave approximation, which neglects the counter-rotating field component. When the a.c. field is sufficiently strong, this approximation fails, leading to a resonance-frequency shift known as the Bloch-Siegert shift. Here, we report the vacuum Bloch-Siegert shift, which is induced by the ultra-strong coupling of matter with the counter-rotating component of the vacuum fluctuation field in a cavity. Specifically, an ultra-high-mobility two-dimensional electron gas inside a high-Q terahertz cavity in a quantizing magnetic field revealed ultra-narrow Landau polaritons, which exhibited a vacuum Bloch-Siegert shift up to 40 GHz. This shift, clearly distinguishable from the photon-field self-interaction effect, represents a unique manifestation of a strong-field phenomenon without a strong field.

  6. Infrared exponents and the strong-coupling limit in lattice Landau gauge

    International Nuclear Information System (INIS)

    Sternbeck, Andre; Smekal, Lorenz von

    2010-01-01

    We study the gluon and ghost propagators of lattice Landau gauge in the strong-coupling limit β=0 in pure SU(2) lattice gauge theory to find evidence of the conformal infrared behavior of these propagators as predicted by a variety of functional continuum methods for asymptotically small momenta q 2 QCD 2 . In the strong-coupling limit, this same behavior is obtained for the larger values of a 2 q 2 (in units of the lattice spacing a), where it is otherwise swamped by the gauge-field dynamics. Deviations for a 2 q 2 <1 are well parameterized by a transverse gluon mass ∝1/a. Perhaps unexpectedly, these deviations are thus no finite-volume effect but persist in the infinite-volume limit. They furthermore depend on the definition of gauge fields on the lattice, while the asymptotic conformal behavior does not. We also comment on a misinterpretation of our results by Cucchieri and Mendes (Phys. Rev. D 81:016005, 2010). (orig.)

  7. Spin effects in high- and low-field magnetotransport experiments in semimagnetic Cd1-xMnxTe heterostructures

    International Nuclear Information System (INIS)

    Betthausen, Christian

    2012-01-01

    Within the framework of this PhD we report on the very first observation of the fractional Quantum Hall Effect (FQHE) in both, a non-magnetic CdTe and a semimagnetic Cd 1-x Mn x Te quantum well device. To our knowledge, this constitutes the first demonstration of this effect in the II-VI material family. Furthermore, our results reveal that the formation of fractional Quantum Hall states is not inhibited by the presence of magnetic impurities in a quantum structure. The second part of this thesis addresses an alternative route to realize efficient spin transistor action. Typically, spin transistor designs relying on spin-orbit interaction principally suffer from low signal levels due to limitations in spin injection efficiency and fast spin decay. Here we present an approach to realize spin transistor action in systems where spin information is protected by propagating it adiabatically. This is achieved by inducing tunable diabatic Landau-Zener transitions that lead to a backscattering of spins and hence allow controlling the transmission of spin-polarized charge carriers through the device, i.e. switching between 'on' and 'off' states. We demonstrate the validity of our approach in a Cd 1-x Mn x Te diluted magnetic semiconductor quantum well structure where efficient spin transport is observed over device distances of 50 μm. In contrast to other spin transistor designs we find that our concept is exceptionally tolerant against disorder.

  8. Landau-Placzek ratio for heat density dynamics and its application to heat capacity of liquids.

    Science.gov (United States)

    Bryk, Taras; Ruocco, Giancarlo; Scopigno, Tullio

    2013-01-21

    Exact relation for contributions to heat capacity of liquids is obtained from hydrodynamic theory. It is shown from analysis of the long-wavelength limit of heat density autocorrelation functions that the heat capacity of simple liquids is represented as a sum of two contributions due to "phonon-like" collective excitations and heat relaxation. The ratio of both contributions being the analogy of Landau-Placzek ratio for heat processes depends on the specific heats ratio. The theory of heat density autocorrelation functions in liquids is verified by computer simulations. Molecular dynamics simulations for six liquids having the ratio of specific heats γ in the range 1.1-2.3, were used for evaluation of the heat density autocorrelation functions and predicted Landau-Placzek ratio for heat processes. The dependence of contributions from collective excitations and heat relaxation process to specific heat on γ is shown to be in excellent agreement with the theory.

  9. Electron collisions in the trapped gyro-Landau fluid transport model

    International Nuclear Information System (INIS)

    Staebler, G. M.; Kinsey, J. E.

    2010-01-01

    Accurately modeling electron collisions in the trapped gyro-Landau fluid (TGLF) equations has been a major challenge. Insights gained from numerically solving the gyrokinetic equation have lead to a significant improvement of the low order TGLF model. The theoretical motivation and verification of this model with the velocity-space gyrokinetic code GYRO[J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)] will be presented. The improvement in the fidelity of TGLF to GYRO is shown to also lead to better prediction of experimental temperature profiles by TGLF for a dedicated collision frequency scan.

  10. Landau-Devonshire Parameters for the Tunable Paraelectric Material BaTi.9(Sc,Ta).05O3

    National Research Council Canada - National Science Library

    Miller, Virginia; Crowne, Frank

    2008-01-01

    ...).05O3 are used to deduce the thermodynamic Landau-Devonshire parameters of the material, which are found to differ strongly from those of the parent material BaTiO3, despite the small amount of added Sc and Ta...

  11. In memory of Alois Apfelbeck: An Interconnection between Cayley-Eisenstein-Pólya and Landau Probability Distributions

    Directory of Open Access Journals (Sweden)

    Vladimír Vojta

    2013-01-01

    Full Text Available The interconnection between the Cayley-Eisenstein-Pólya distribution and the Landau distribution is studied, and possibly new transform pairs for the Laplace and Mellin transform and integral expressions for the Lambert W function have been found.

  12. Specific heat of Ginzburg-Landau fields in the n-1 expansion

    International Nuclear Information System (INIS)

    Bray, A.J.

    1975-01-01

    The n -1 expansion for the specific heat C/subv/ of the n-component Ginzburg-Landau model is discussed in terms of an n -1 expansion for the irreducible polarization. In the low-temperature limit, each successive term of the latter expansion diverges more strongly than the last, invalidating a truncation of this series at any finite order in 1/n. The most divergent terms in each order are identified and summed. The results provide justification for the usual truncated expansions for C/subv/

  13. The finite dimensional behaviour of the global attractors for the generalized Landau-Lifshitz equation on compact manifolds

    International Nuclear Information System (INIS)

    Guo Boling

    1994-01-01

    We prove the existence of the global attractors for the generalized Landau-Lifshitz equation on compact manifold M, and give the upper and lower estimates of their Hausdorff and fractal dimensions. (author). 18 refs

  14. The constraint for the lowest Landau level and the effective field theory approach for the fractional quantum hall system

    International Nuclear Information System (INIS)

    Ma Zhongshui; Su Zhaobin.

    1992-09-01

    By applying the Dirac quantization method, we build the constraint that all electrons are in the lowest Landau level into the Chern-Simons field theory approach for the fractional quantum Hall system and show that the constraint can be transmuted from hierarchy to hierarchy. For a finite system, we derive that the action for each hierarchy can be split into two parts: a surface part provides the action for the edge excitations while the remaining part is precisely the bulk action for the next hierarchy. An the action for the edge could be decoupled from the bulk only at the hierarchy filling. (author). 16 refs

  15. Global a priori estimates for the inhomogeneous Landau equation with moderately soft potentials

    Science.gov (United States)

    Cameron, Stephen; Silvestre, Luis; Snelson, Stanley

    2018-05-01

    We establish a priori upper bounds for solutions to the spatially inhomogeneous Landau equation in the case of moderately soft potentials, with arbitrary initial data, under the assumption that mass, energy and entropy densities stay under control. Our pointwise estimates decay polynomially in the velocity variable. We also show that if the initial data satisfies a Gaussian upper bound, this bound is propagated for all positive times.

  16. Generalized Landau-Lifshitz-Gilbert equation for uniformly magnetized bodies

    Energy Technology Data Exchange (ETDEWEB)

    Serpico, C. [Dipartimento di Ingegneria Elettrica, Universita di Napoli ' FedericoII' , Via Claudio 21, I-80125 Naples (Italy)], E-mail: serpico@unina.it; Mayergoyz, I.D. [ECE Department and UMIACS, University of Maryland, College Park, MD 20742 (United States); Bertotti, G. [Istituto Nazionale di Ricerca Metrologica (INRiM), I-10135 Turin (Italy); D' Aquino, M. [Dipartimento per le Tecnologie, University of Napoli ' Parthenope' , I-80133 Naples (Italy); Bonin, R. [Istituto Nazionale di Ricerca Metrologica (INRiM), I-10135 Turin (Italy)

    2008-02-01

    We consider generalized Landau-Lifshitz-Gilbert (LLG) deterministic dynamics in uniformly magnetized bodies. The dynamics take place on the unit sphere {sigma}, and are characterized by a vector field v tangential to {sigma}. By using Helmholtz decomposition on {sigma}, it is proven that v is uniquely defined by two potentials {chi} and {psi}. Potential {chi} can be identified with the free energy of the system, while {psi} describes non-conservative interactions of the system with the environment. The presence of {psi} modifies the usual energy balance of LLG dynamics. Instead of purely relaxation dynamics we may have steady injection of energy through non-conservative interactions. The implications of the new form of the energy balance are discussed in detail.

  17. Remarks on the Landau-Ginzburg potential and RG-flow for SU(2)-coset models

    International Nuclear Information System (INIS)

    Marzban, C.

    1989-09-01

    The existence of a Landau-Ginzburg (LG)-field for the SU(2)-coset models is motivated and conjectured. The general form of the LG potential for the A-series is found, and the RG-flow pattern suggested by this is shown to agree with that found by other authors, thereby further supporting the conjecture. (author). 17 refs

  18. Frictional lubricity enhanced by quantum mechanics.

    Science.gov (United States)

    Zanca, Tommaso; Pellegrini, Franco; Santoro, Giuseppe E; Tosatti, Erio

    2018-04-03

    The quantum motion of nuclei, generally ignored in the physics of sliding friction, can affect in an important manner the frictional dissipation of a light particle forced to slide in an optical lattice. The density matrix-calculated evolution of the quantum version of the basic Prandtl-Tomlinson model, describing the dragging by an external force of a point particle in a periodic potential, shows that purely classical friction predictions can be very wrong. The strongest quantum effect occurs not for weak but for strong periodic potentials, where barriers are high but energy levels in each well are discrete, and resonant Rabi or Landau-Zener tunneling to states in the nearest well can preempt classical stick-slip with nonnegligible efficiency, depending on the forcing speed. The resulting permeation of otherwise unsurmountable barriers is predicted to cause quantum lubricity, a phenomenon which we expect should be observable in the recently implemented sliding cold ion experiments.

  19. Observing pure effects of counter-rotating terms without ultrastrong coupling: A single photon can simultaneously excite two qubits

    Science.gov (United States)

    Wang, Xin; Miranowicz, Adam; Li, Hong-Rong; Nori, Franco

    2017-12-01

    The coherent process that a single photon simultaneously excites two qubits has recently been theoretically predicted by Garziano et al. [L. Garziano, V. Macrì, R. Stassi, O. Di Stefano, F. Nori, and S. Savasta, One Photon Can Simultaneously Excite two or More Atoms, Phys. Rev. Lett. 117, 043601 (2016), 10.1103/PhysRevLett.117.043601]. We propose a different approach to observe a similar dynamical process based on a superconducting quantum circuit, where two coupled flux qubits longitudinally interact with the same resonator. We show that this simultaneous excitation of two qubits (assuming that the sum of their transition frequencies is close to the cavity frequency) is related to the counter-rotating terms in the dipole-dipole coupling between two qubits, and the standard rotating-wave approximation is not valid here. By numerically simulating the adiabatic Landau-Zener transition and Rabi-oscillation effects, we clearly verify that the energy of a single photon can excite two qubits via higher-order transitions induced by the longitudinal couplings and the counter-rotating terms. Compared with previous studies, the coherent dynamics in our system only involves one intermediate state and, thus, exhibits a much faster rate. We also find transition paths which can interfere. Finally, by discussing how to control the two longitudinal-coupling strengths, we find a method to observe both constructive and destructive interference phenomena in our system.

  20. Dirac mechanics and Landau two-fluid model in /sup 4/HeII

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Gomez, J [Instituto Universitario Pedagogico de Caracas (Venezuela). Dept. de Matematica y Fisica

    1980-07-01

    This paper is devoted to the development of the Dirac formalism for singular systems when applied to the Landau two-fluid model in superfluid helium. Notably, the Hamiltonian density is weakly zero (in the sense of Dirac). We obtain the physical and gauge variables and show that all the constraints are of first class and hence that the Dirac bracket coincides with the Poisson bracket. The quantization of this system is left for a future paper.

  1. Propagation of neutrinos in nuclear matter; Effets du milieu sur la propagation des neutrinos dans la matiere nucleaire

    Energy Technology Data Exchange (ETDEWEB)

    Margueron, J

    2001-07-01

    We study the elementary interactions between neutrinos and dense matter in a proto-neutron star. Equations of state obtained with different nuclear effective interactions (Skyrme, Gogny, Relativistic Lagrangians) are first discussed. Then, we characterize their stability in spin and isospin. We derive magnetic susceptibilities for all isospin asymmetry values as a function of Landau parameters G{sup {pi}}{sup {pi}}{sup '}{sub 0} (where {pi}, {pi}' = proton or neutron). From this work, we select a parametrization for each of the 3 effective forces: Sly230b,D1P,NL3. We calculate the pure neutron matter and asymmetric nuclear matter response functions with and without charge exchange, describing nuclear correlations in both approaches: non-relativistic (Hartree-Fock with Skyrme forces, then complete RPA) and relativistic (in the Hartree approximation). At the end, we calculate neutrino mean free paths neutral current and charged current reactions. Comparisons between relativistic and non-relativistic approaches allow us to identify relativistic effects in nuclear matter at densities as low as twice the saturation density. RPA correlations make the medium more transparent to neutrinos compared to free Fermi gas. The importance of the effective mass in mean free path calculations is also shown. (author)

  2. Light-field-driven currents in graphene

    Science.gov (United States)

    Higuchi, Takuya; Heide, Christian; Ullmann, Konrad; Weber, Heiko B.; Hommelhoff, Peter

    2017-10-01

    The ability to steer electrons using the strong electromagnetic field of light has opened up the possibility of controlling electron dynamics on the sub-femtosecond (less than 10-15 seconds) timescale. In dielectrics and semiconductors, various light-field-driven effects have been explored, including high-harmonic generation, sub-optical-cycle interband population transfer and the non-perturbative change of the transient polarizability. In contrast, much less is known about light-field-driven electron dynamics in narrow-bandgap systems or in conductors, in which screening due to free carriers or light absorption hinders the application of strong optical fields. Graphene is a promising platform with which to achieve light-field-driven control of electrons in a conducting material, because of its broadband and ultrafast optical response, weak screening and high damage threshold. Here we show that a current induced in monolayer graphene by two-cycle laser pulses is sensitive to the electric-field waveform, that is, to the exact shape of the optical carrier field of the pulse, which is controlled by the carrier-envelope phase, with a precision on the attosecond (10-18 seconds) timescale. Such a current, dependent on the carrier-envelope phase, shows a striking reversal of the direction of the current as a function of the driving field amplitude at about two volts per nanometre. This reversal indicates a transition of light-matter interaction from the weak-field (photon-driven) regime to the strong-field (light-field-driven) regime, where the intraband dynamics influence interband transitions. We show that in this strong-field regime the electron dynamics are governed by sub-optical-cycle Landau-Zener-Stückelberg interference, composed of coherent repeated Landau-Zener transitions on the femtosecond timescale. Furthermore, the influence of this sub-optical-cycle interference can be controlled with the laser polarization state. These coherent electron dynamics in

  3. Threshold behavior in electron-atom scattering

    International Nuclear Information System (INIS)

    Sadeghpour, H.R.; Greene, C.H.

    1996-01-01

    Ever since the classic work of Wannier in 1953, the process of treating two threshold electrons in the continuum of a positively charged ion has been an active field of study. The authors have developed a treatment motivated by the physics below the double ionization threshold. By modeling the double ionization as a series of Landau-Zener transitions, they obtain an analytical formulation of the absolute threshold probability which has a leading power law behavior, akin to Wannier's law. Some of the noteworthy aspects of this derivation are that the derivation can be conveniently continued below threshold giving rise to a open-quotes cuspclose quotes at threshold, and that on both sides of the threshold, absolute values of the cross sections are obtained

  4. Single-electron capture in low-energy Ar6+-He collisions

    International Nuclear Information System (INIS)

    Akguengoer, K.; Kamber, E.Y.; Ferguson, S.M.

    1997-01-01

    Double differential cross sections for state-selective single-electron capture processes in Ar 6+ -He collisions have been measured at laboratory energies between 75 and 900 eV and scattering angles between 0 and 8 . At the lowest energy, the zero-angle spectrum shows capture into Ar 5+ (4p) to be the most important channel. However, as the scattering angle is increased, a second peak appears at angles ≥2 and becomes more pronounced relative to the 4p capture channel. The energy spectra are interpreted qualitatively in terms of the reaction windows, which are calculated using the single-crossing Landau-Zener model. Total and differential cross sections are also measured and compared with available measurements and calculations. (orig.)

  5. Microwave ionization and excitation of Ba Rydberg atoms

    International Nuclear Information System (INIS)

    Eichmann, U.; Dexter, J.L.; Xu, E.Y.; Gallagher, T.F.

    1989-01-01

    We have investigated ionization and excitation of the Ba 6sn s 1 S 0 and 6snd 1,3 D 2 series in strong microwave fields. The observed microwave ionization threshold fields, scaling as 0.28 n -5 , and the state mixing fields cannot be completely explained in terms of a single cycle Landau-Zener model. However, by taking into account multiphoton resonant transitions driven by many cycles of the microwave field we have been able to interpret the data. In particular multi-photon transitions have been found to be responsible for apparent resonance structures and for the unexpectedly low mixing fields. Not surprisingly, doubly excited valence states introduce irregularities into both the microwave ionization and the state mixing field values. (orig.)

  6. Nuclear famine: The indirect effects of nuclear war

    International Nuclear Information System (INIS)

    Harwell, M.A.; Harwell, C.C.

    1986-01-01

    The indirect effects of a nuclear war, especially as mediated by disruption in food availability, could be much more extensive than the direct effects. Furthermore, this risk is especially severe for noncombatant countries - for the 4 billion or so humans expected to survive the immediate period after a nuclear war relatively physically unharmed. Thus, a fundamentally different picture of the post-nuclear-war world results, where a large-scale nuclear war between the United States and the Soviet Union would probably result in more eventual fatalities in India than in the United States and the Soviet Union combined, and more people would die on the African continent than in all of Europe. Rather than reflecting images of Hiroshima and Nagasaki, a modern nuclear war would, for most of the people of the world, much more resemble current images of Ethiopia and the Sudan

  7. Spin effects in high- and low-field magnetotransport experiments in semimagnetic Cd{sub 1-x}Mn{sub x}Te heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Betthausen, Christian

    2012-07-09

    Within the framework of this PhD we report on the very first observation of the fractional Quantum Hall Effect (FQHE) in both, a non-magnetic CdTe and a semimagnetic Cd{sub 1-x}Mn{sub x}Te quantum well device. To our knowledge, this constitutes the first demonstration of this effect in the II-VI material family. Furthermore, our results reveal that the formation of fractional Quantum Hall states is not inhibited by the presence of magnetic impurities in a quantum structure. The second part of this thesis addresses an alternative route to realize efficient spin transistor action. Typically, spin transistor designs relying on spin-orbit interaction principally suffer from low signal levels due to limitations in spin injection efficiency and fast spin decay. Here we present an approach to realize spin transistor action in systems where spin information is protected by propagating it adiabatically. This is achieved by inducing tunable diabatic Landau-Zener transitions that lead to a backscattering of spins and hence allow controlling the transmission of spin-polarized charge carriers through the device, i.e. switching between 'on' and 'off' states. We demonstrate the validity of our approach in a Cd{sub 1-x}Mn{sub x}Te diluted magnetic semiconductor quantum well structure where efficient spin transport is observed over device distances of 50 {mu}m. In contrast to other spin transistor designs we find that our concept is exceptionally tolerant against disorder.

  8. Asymmetric Landau bands due to spin–orbit coupling

    International Nuclear Information System (INIS)

    Erlingsson, Sigurdur I; Manolescu, Andrei; Marinescu, D C

    2015-01-01

    We show that the Landau bands obtained in a two-dimensional lateral semiconductor superlattice with spin–orbit coupling (SOC) of the Rashba/Dresselhaus type, linear in the electron momentum, placed in a tilted magnetic field, do not follow the symmetry of the spatial modulation. Moreover, this phenomenology is found to depend on the relative tilt of magnetic field and on the SOC type: (a) when only Rashba SOC exists and the magnetic field is tilted in the direction of the superlattice (b) Dresselhaus SOC exists and the magnetic field is tilted in the direction perpendicular to the superlattice. Consequently, measurable properties of the modulated system become anisotropic in a tilted magnetic field when the field is conically rotated around the z axis, at a fixed polar angle, as we demonstrate by calculating the resistivity and the magnetization. (paper)

  9. Berry phases for Landau Hamiltonians on deformed tori

    Science.gov (United States)

    Lévay, Péter

    1995-06-01

    Parametrized families of Landau Hamiltonians are introduced, where the parameter space is the Teichmüller space (topologically the complex upper half plane) corresponding to deformations of tori. The underlying SO(2,1) symmetry of the families enables an explicit calculation of the Berry phases picked up by the eigenstates when the torus is slowly deformed. It is also shown that apart from these phases that are local in origin, there are global non-Abelian ones too, related to the hidden discrete symmetry group Γϑ (the theta group, which is a subgroup of the modular group) of the families. The induced Riemannian structure on the parameter space is the usual Poincare metric on the upper half plane of constant negative curvature. Due to the discrete symmetry Γϑ the geodesic motion restricted to the fundamental domain of this group is chaotic.

  10. Energie du type Ginzburg-Landau avec un terme de chevillage

    OpenAIRE

    AMARI, Nassima

    2010-01-01

    L’objectif de ce travail est l’étude d’un modèle bidimensionnel de Ginzburg-Landau avec un problème de l’ancrage (pinning) des vortex. La principale difficulté en réitérant l’approche faite par F. Béthuel, H. Brézis et F. Hélein, résulte du fait que la construction de mauvais disques ne soit pas évidente. Pour surmonter cette difficulté,on remplace le minimiseur u epsilon par v epsilon U epsilon. Cette substitution nous conduit à l'étude d'une énergie classique (qui correspond à p=1). ...

  11. Some aspects of nuclear dynamics

    International Nuclear Information System (INIS)

    Gregoire, C.

    1987-01-01

    First the BBGKY hierarchy of equations is presented; the method developed here lies on a reduction procedure of a many body density distribution function. From the equations, Hartree and Hartree-Fock approximations are deduced, and time dependent Hartree-Fock equation. Then two derivations of a nuclear reaction kinetic equation are presented: the Woldmann-Snider equation and the Botermans-Malfliet equation. The Wigner transformation is used and the Landau-Vlasov equation is studied. (Or Vlasov-Uehling-Uhlenbeck or Boltzmann-Uehling-Uhlenbeck equation). Keypoints of approximate solutions are mentioned. Simulation calculations of phenomenological collisions are shown. Then dynamics of heavy ion reactions is studied from results presented

  12. Superradiance From Molecular Nanomagnets

    Science.gov (United States)

    Chudnovsky, Eugene M.

    2003-03-01

    Magnetic dipolar transitions in individual magnetic molecules occur with a very low probability. However, typical wavelengths of the corresponding electromagnetic radiation are in the millimeter range, that is, comparable to the crystal size. This may result in the superradiance: The coherent emission of the electromagnetic radiation by the entire crystal, with the rate increased by the total number of molecules as compared to the rate of the individual emission. Rigorous theory of the superradiant resonant magnetic relaxation will be presented, that generalizes the Landau-Zener effect for the case of a macroscopic number of magnetic molecules coupled through the electromagnetic radiation [1]. Possible evidence of coherent electromagnetic effects in crystals of molecular nanomagnets placed inside a resonant cavity will be reported [2]. (This work has been supported by the NSF grant No. DMR-9978882.) [1] E. M. Chudnovsky and D. A. Garanin, Phys. Rev. Lett. 89, 157201 (7 Oct 2002). [2] J. Tejada, E. M. Chudnovsky, R. Amigo, and J. M. Hernandez, cond-mat/0210340 (16 Oct 2002).

  13. On the Aharonov-Casher system and the Landau-Aharonov-Casher system confined to a two-dimensional quantum ring

    International Nuclear Information System (INIS)

    Bakke, K.; Furtado, C.

    2012-01-01

    We study the quantum dynamics of a neutral particle in the Aharonov-Casher system and in the Landau-Aharonov-Casher system confined to a two-dimensional quantum ring, a quantum dot, and a quantum anti-dot potentials described by the Tan-Inkson model [W.-C. Tan and J. C. Inkson, Semicond. Sci. Technol. 11, 1635 (1996)]. We show, in the Aharonov-Casher system, that bound states can be achieved when the neutral particle is confined to the two-dimensional quantum ring and the quantum dot and discuss the appearance of persistent currents. In the Landau-Aharonov-Casher system, we show that bound states can be achieved when the neutral particle is confined to the quantum anti-dot, quantum dot, and the two-dimensional quantum ring, but there are no persistent currents.

  14. Renormalization group equations and the Lifshitz point in noncommutative Landau-Ginsburg theory

    International Nuclear Information System (INIS)

    Chen, G.-H.; Wu, Y.-S.

    2002-01-01

    A one-loop renormalization group (RG) analysis is performed for noncommutative Landau-Ginsburg theory in an arbitrary dimension. We adopt a modern version of the Wilsonian RG approach, in which a shell integration in momentum space bypasses the potential IR singularities due to UV-IR mixing. The momentum-dependent trigonometric factors in interaction vertices, characteristic of noncommutative geometry, are marginal under RG transformations, and their marginality is preserved at one loop. A negative Θ-dependent anomalous dimension is discovered as a novel effect of the UV-IR mixing. We also found a noncommutative Wilson-Fisher (NCWF) fixed point in less than four dimensions. At large noncommutativity, a momentum space instability is induced by quantum fluctuations, and a consequential first-order phase transition is identified together with a Lifshitz point in the phase diagram. In the vicinity of the Lifshitz point, we introduce two critical exponents ν m and β k , whose values are determined to be 1/4 and 1/2, respectively, at mean-field level

  15. Finding equilibrium in the spatiotemporal chaos of the complex Ginzburg-Landau equation

    Science.gov (United States)

    Ballard, Christopher C.; Esty, C. Clark; Egolf, David A.

    2016-11-01

    Equilibrium statistical mechanics allows the prediction of collective behaviors of large numbers of interacting objects from just a few system-wide properties; however, a similar theory does not exist for far-from-equilibrium systems exhibiting complex spatial and temporal behavior. We propose a method for predicting behaviors in a broad class of such systems and apply these ideas to an archetypal example, the spatiotemporal chaotic 1D complex Ginzburg-Landau equation in the defect chaos regime. Building on the ideas of Ruelle and of Cross and Hohenberg that a spatiotemporal chaotic system can be considered a collection of weakly interacting dynamical units of a characteristic size, the chaotic length scale, we identify underlying, mesoscale, chaotic units and effective interaction potentials between them. We find that the resulting equilibrium Takahashi model accurately predicts distributions of particle numbers. These results suggest the intriguing possibility that a class of far-from-equilibrium systems may be well described at coarse-grained scales by the well-established theory of equilibrium statistical mechanics.

  16. Nonlinear mean field theory for nuclear matter and surface properties

    International Nuclear Information System (INIS)

    Boguta, J.; Moszkowski, S.A.

    1983-01-01

    Nuclear matter properties are studied in a nonlinear relativistic mean field theory. We determine the parameters of the model from bulk properties of symmetric nuclear matter and a reasonable value of the effective mass. In this work, we stress the nonrelativistic limit of the theory which is essentially equivalent to a Skyrme hamiltonian, and we show that most of the results can be obtained, to a good approximation, analytically. The strength of the required parameters is determined from the binding energy and density of nuclear matter and the effective nucleon mass. For realistic values of the parameters, the nonrelativistic approximation turns out to be quite satisfactory. Using reasonable values of the parameters, we can account for other key properties of nuclei, such as the spin-orbit coupling, surface energy, and diffuseness of the nuclear surface. Also the energy dependence of the nucleon-nucleus optical model is accounted for reasonably well except near the Fermi surface. It is found, in agreement with empirical results, that the Landau parameter F 0 is quite small in normal nuclear matter. Both density dependence and momentum dependence of the NN interaction, but especially the former, are important for nuclear saturation. The required scalar and vector coupling constants agree fairly well with those obtained from analyses of NN scattering phase shifts with one-boson-exchange models. The mean field theory provides a semiquantitative justification for the weak Skyrme interaction in odd states. The strength of the required nonlinear term is roughly consistent with that derived using a new version of the chiral mean field theory in which the vector mass as well as the nucleon mass is generated by the sigma-field. (orig.)

  17. Landau-Kleffner Syndrome, Electrical Status Epilepticus in Slow Wave Sleep, and Language Regression in Children

    Science.gov (United States)

    McVicar, Kathryn A.; Shinnar, Shlomo

    2004-01-01

    The Landau-Kleffner syndrome (LKS) and electrical status epilepticus in slow wave sleep (ESES) are rare childhood-onset epileptic encephalopathies in which loss of language skills occurs in the context of an epileptiform EEG activated in sleep. Although in LKS the loss of function is limited to language, in ESES there is a wider spectrum of…

  18. Infrared Behavior of Gluon and Ghost Propagators in Landau Gauge QCD

    International Nuclear Information System (INIS)

    von Smekal, L.; Hauck, A.; Alkofer, R.

    1997-01-01

    A truncation scheme for the Dyson-Schwinger equations of Euclidean QCD in Landau gauge is presented. It implements the Slavnov-Taylor identities for the three-gluon and ghost-gluon vertices, whereas irreducible four-gluon couplings as well as the gluon-ghost and ghost-ghost scattering kernels are neglected. The infrared behavior of gluon and ghost propagators is obtained analytically: The gluon propagator vanishes for small momenta, whereas the ghost propagator diverges strongly. The numerical solutions are compared with recent lattice results. The running coupling approaches a fixed point, α c ≅9.5 , in the infrared. copyright 1997 The American Physical Society

  19. Theory of a condensed charged-Bose, charged Fermi gas and Ginzburg--Landau studies of superfluid 3He

    International Nuclear Information System (INIS)

    Dahl, D.A.

    1976-01-01

    Two independent topics in the field of condensed matter physics are examined: the condensed charged-Bose, charged Fermi gas and superfluid 3 He. Green's function (field theoretic) methods are used to derive the low-temperature properties of a dense, neutral gas of condensed charged bosons and degenerate charged fermions. Restriction is made to the case where the fermion mass is much lighter than the boson mass. Linear response and the density-density correlation function are examined and shown to exhibit two collective modes: a plasmon branch and a phonon branch with speed equal to that of ionic sound in solids. Comparison with a possible astrophysical application (white dwarf stars) is made. The behavior near the superfluid transition temperature (Ginzburg--Landau regime) of 3 He is then studied. Gorkov equations are derived and studied in the weak-coupling limit. In this way the form and order of magnitude estimates of coefficients appearing in the Ginzburg--Landau theory are obtained. Weak-coupling particle and spin currents are derived. Various perturbations break the large degeneracy of the states and have experimental implications. The electric contribution to the Ginzburg--Landau free energy is studied for the proposed A and B phases. Imposition of an electric field orients the axial state, but does not give rise to shifts in the NMR resonances. Shifts and discontinuous jumps in the longitudinal and transverse signals are predicted for the Balian--Werthamer state, the details depending on the relative strengths of the fields, as well as the angle between them

  20. Nuclear energy and greenhouse effect

    International Nuclear Information System (INIS)

    Strub, R.A.

    1991-01-01

    The contribution of nuclear power plants against the greenhouse effects is evaluated, not only nuclear energy is unable to fight greenhouse effect increase but long life wastes endanger environment. 8 refs

  1. Fine structure of the isoscalar giant quadrupole resonance in 40Ca due to Landau damping?

    International Nuclear Information System (INIS)

    Usman, I.; Buthelezi, Z.; Carter, J.; Cooper, G.R.J.; Fearick, R.W.; Foertsch, S.V.; Fujita, H.; Fujita, Y.; Kalmykov, Y.; Neumann-Cosel, P. von; Neveling, R.; Papakonstantinou, P.; Richter, A.; Roth, R.; Shevchenko, A.; Sideras-Haddad, E.; Smit, F.D.

    2011-01-01

    The fragmentation of the Isoscalar Giant Quadrupole Resonance (ISGQR) in 40 Ca has been investigated in high energy-resolution experiments using proton inelastic scattering at E p =200 MeV. Fine structure is observed in the region of the ISGQR and its characteristic energy scales are extracted from the experimental data by means of a wavelet analysis. The experimental scales are well described by Random Phase Approximation (RPA) and second-RPA calculations with an effective interaction derived from a realistic nucleon-nucleon interaction by the Unitary Correlation Operator Method (UCOM). In these results characteristic scales are already present at the mean-field level pointing to their origination in Landau damping, in contrast to the findings in heavier nuclei and also to SRPA calculations for 40 Ca based on phenomenological effective interactions, where fine structure is explained by the coupling to two-particle-two-hole (2p-2h) states.

  2. First-principles-based Landau-Devonshire potential for BiFeO.sub.3./sub.

    Czech Academy of Sciences Publication Activity Database

    Márton, Pavel; Klíč, Antonín; Pasciak, Marek; Hlinka, Jiří

    2017-01-01

    Roč. 96, č. 17 (2017), s. 1-5, č. článku 174110. ISSN 2469-9950 R&D Projects: GA ČR GA15-04121S Grant - others:GA MŠk(CZ) LM2015042 Institutional support: RVO:68378271 Keywords : Landau-Devonshire potential * first-principles calculations * BiFeO3 * Energy-sampling technique Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 3.836, year: 2016

  3. MD 2197: Experimental studies of Landau damping by means of Beam Transfer Function measurements in the presence of beam-beam interactions and diffusive mechanisms

    CERN Document Server

    Tambasco, Claudia; Barranco Garcia, Javier; Boccardi, Andrea; Buffat, Xavier; Bruce, Roderik; Gasior, Marek; Hostettler, Michi; Lefevre, Thibaut; Louro Alves, Diogo Miguel; Metral, Elias; Persson, Tobias Hakan Bjorn; Pieloni, Tatiana; Pojer, Mirko; Salvachua Ferrando, Belen Maria; Solfaroli Camillocci, Matteo; CERN. Geneva. ATS Department

    2018-01-01

    Beam Transfer Function (BTF) measurements are direct measurement of the stability diagrams that define the stability threshold of coherent beam instabilities driven by the impedance. At the LHC, some coherent instabilities at flat top energy are still not fully understood and the BTF measurements provide a method to experimentally probe the Landau damping of the proton beams. The BTF response is sensitive to the particle distribution changes and contain information about the transverse tune spread in the beams. The BTF system has been installed in the LHC in the 2015 in order to investigate the Landau damping at different stages of the operational cycle, machine configurations (different octupole currents, crossing angles, tunes etc...) and in presence of beam-beam excited resonances that may provoke diffusion mechanisms with a consequence change of Landau damping. Past MDs showed some difficulties for the reconstruction of the stability diagram from BTF measurements and several improvements on the BTF sy...

  4. El síndrome de Landau-Kleffner: Presentación de dos casos Landau-Kleffner's syndrome: Reports of two cases

    Directory of Open Access Journals (Sweden)

    Albia J. Pozo Alonso

    2005-06-01

    Full Text Available Se presentan dos niños que reúnen los criterios clínicos y electroencefalográficos del síndrome de Landau-Kleffner. En uno de los pacientes las dificultades para comprender el lenguaje y para la expresión oral espontánea comenzaron a manifestarse a los 6 años, y en el otro caso a los 6 años y 9 meses. Uno de los niños no ha presentado crisis epilépticas hasta el momento actual. En este paciente la tomografía computadorizada por emisión de positrón único (SPECT cerebral mostró una ligera hipoperfusión temporoparietal posterior bilateral. En el niño que presenta crisis epilépticas; éstas se iniciaron a la edad de 2 años y 6 meses y eran focales simples motoras que se generalizaron secundariamente. Desde hace un año no presenta crisis. Desde el punto de vista clínico y electroencefalográfico, ambos pacientes tuvieron una respuesta favorable al tratamiento con prednisona. En un niño, aunque ha mejorado, persisten las dificultades para la comprensión y la expresión orales. Se concluye que son muy importantes para el diagnóstico de este síndrome la existencia de una afasia adquirida y las descargas observadas en el electroencefalogramaTwo children with the clinical and electroencephalographic criteria of Landau-Kleffner's syndrome are presented. In one of the patients, the difficulties for understanding the language and for the spontaneous oral expression started at 6 years old. In the other case, they were manifested at 6 years and 9 months old. One of the children has not had epileptic seizures so far. In this patient, the single positron emission computerized tomography (brain SPECT showed a mild bilateral posterior temporoparietal hypoperfusion. The epileptic seizures in the other child started when he was 2 years and 6 months old and were focal , simple, motor and secondarily generalized. He has not had seizures for a year. Both patients had a favorable response to prednisone from the clinical and

  5. Critical initial-slip scaling for the noisy complex Ginzburg–Landau equation

    International Nuclear Information System (INIS)

    Liu, Weigang; Täuber, Uwe C

    2016-01-01

    We employ the perturbative fieldtheoretic renormalization group method to investigate the universal critical behavior near the continuous non-equilibrium phase transition in the complex Ginzburg–Landau equation with additive white noise. This stochastic partial differential describes a remarkably wide range of physical systems: coupled nonlinear oscillators subject to external noise near a Hopf bifurcation instability; spontaneous structure formation in non-equilibrium systems, e.g., in cyclically competing populations; and driven-dissipative Bose–Einstein condensation, realized in open systems on the interface of quantum optics and many-body physics, such as cold atomic gases and exciton-polaritons in pumped semiconductor quantum wells in optical cavities. Our starting point is a noisy, dissipative Gross–Pitaevski or nonlinear Schrödinger equation, or equivalently purely relaxational kinetics originating from a complex-valued Landau–Ginzburg functional, which generalizes the standard equilibrium model A critical dynamics of a non-conserved complex order parameter field. We study the universal critical behavior of this system in the early stages of its relaxation from a Gaussian-weighted fully randomized initial state. In this critical aging regime, time translation invariance is broken, and the dynamics is characterized by the stationary static and dynamic critical exponents, as well as an independent ‘initial-slip’ exponent. We show that to first order in the dimensional expansion about the upper critical dimension, this initial-slip exponent in the complex Ginzburg–Landau equation is identical to its equilibrium model A counterpart. We furthermore employ the renormalization group flow equations as well as construct a suitable complex spherical model extension to argue that this conclusion likely remains true to all orders in the perturbation expansion. (paper)

  6. On Landau Scenario of Chaotization for Beam Distribution

    International Nuclear Information System (INIS)

    Parsa, Z.; Zadorozhny, V.

    1999-01-01

    We examine a problem in nonlinear dynamics in which both regular and chaotic motions are possible. Thus we deal with some of the fundamental theoretical problem of accelerator physics, mathematics theory of dynamical systems, and other fields of physics. The focus is on the appearance of chaos in a beam distribution. A study of the problem is based on two observations. The First observation is that using Lyapunov method and its extension we obtain solutions of partial differential equations. Using this approach we discuss the problem of finding a solution of Vlasov-Poisson equation, i.e., some stationary solution where we consider magnetic field as some disturbance with a small parameter. Thus the solution of Vlasov equation yields an asymptotic series such that the solution of Vlasov-Poisson equation is the basis solution for one. The second observation is that physical chaos is weakly limit of, well known, the Landau bifurcation's. This fact we have proved using ideas on the Nature of Turbulence

  7. Electric-field induced spin accumulation in the Landau level states of topological insulator thin films

    Science.gov (United States)

    Siu, Zhuo Bin; Chowdhury, Debashree; Basu, Banasri; Jalil, Mansoor B. A.

    2017-08-01

    A topological insulator (TI) thin film differs from the more typically studied thick TI system in that the former has both a top and a bottom surface where the states localized at both surfaces can couple to one other across the finite thickness. An out-of-plane magnetic field leads to the formation of discrete Landau level states in the system, whereas an in-plane magnetization breaks the angular momentum symmetry of the system. In this work, we study the spin accumulation induced by the application of an in-plane electric field to the TI thin film system where the Landau level states and inter-surface coupling are simultaneously present. We show, via Kubo formula calculations, that the in-plane spin accumulation perpendicular to the magnetization due to the electric field vanishes for a TI thin film with symmetric top and bottom surfaces. A finite in-plane spin accumulation perpendicular to both the electric field and magnetization emerges upon applying either a differential magnetization coupling or a potential difference between the two film surfaces. This spin accumulation results from the breaking of the antisymmetry of the spin accumulation around the k-space equal-energy contours.

  8. Solutions of the two-level problem in terms of biconfluent Heun functions

    Energy Technology Data Exchange (ETDEWEB)

    Ishkhanyan, Artur [Engineering Center of Armenian National Academy of Sciences, Ashtarak (Armenia)]. E-mail: artur@ec.sci.am; Suominen, Kalle-Antti [Helsinki Institute of Physics, Helsinki (Finland); Department of Applied Physics, University of Turku, Turku (Finland)

    2001-08-17

    Five four-parametric classes of quantum mechanical two-level models permitting solutions in terms of the biconfluent Heun function are derived. Three of these classes are generalizations of the well known classes of Landau-Zener, Nikitin and Crothers. It is shown that two other classes describe super- and sublinear and essentially nonlinear level crossings, as well as processes with three crossing points. In particular, these classes include two-level models where the field amplitude is constant and the detuning varies as {delta}{sub 0}t+{delta}{sub 2}t{sup 3} or {approx}t{sup 1/3}. For the essentially nonlinear cubic-crossing model, {delta}{sub t}{approx}{delta}{sub 2}t{sup 3}, the general solution of the two-level problem is shown to be expressed as series of confluent hypergeometric functions. (author)

  9. Electron capture by multicharged ions at eV energies

    International Nuclear Information System (INIS)

    Havener, C.C.; Huq, M.S.; Meyer, F.W.; Phaneuf, R.A.

    1988-01-01

    A multicharged ion-atom merged-beams apparatus has been used in conjunction with the ORNL-ECR ion source to measure accurate absolute electron-capture cross sections in the energy range from below 1 eV/amu to 1500 eV/amu. Measurements for N/sup 3+,4+,5+/ /plus/ H(D) collisions indicate good agreement with available theoretical calculations. However, measurements with O 5+ /plus/ H(D) show an unexpected low-energy behavior which may be attributable to the ion-induced-dipole attraction between the reactants. Scaled Landau-Zener calculations presented here identify a transfer plus excitation channel which has the correct energy dependence at low energies. This finding suggest the need for a comprehensive coupled channel calculation which would include such product states. 25 refs., 8 figs

  10. Nuclear explosions and their effects

    Energy Technology Data Exchange (ETDEWEB)

    1958-01-01

    A brief historical background is given of the development of the atomic bomb. Also included is an account of the Hiroshima-Nagasaki bombing, plus some information on the testing and production of nuclear weapons by the United States, United Kingdom, and Russia. More detailed consideration is given to the following: the scientific principles of fission and fusion explosions; the energy released in fission and the radioactivity of fission products; blast, thermal, and radiologicalal effects of nuclear explosions; long-term radiological hazards from fall-out; and genetic effects of nuclear explosions. A brief account is given of the fission chain process, the concept of critical size, and the principles of implosion as applied to nuclear explosions. Limited information is presented on the controlled release of thermonuclear energy and catalyzed fusion reaction. Discussions are included on dose rates from radiation sources inside and outside the body, the effect of nuclear explosions on the weather, and the contamination of fish and marine organisms.

  11. Probing bulk physics in the 5/2 fractional quantum Hall effect using the Corbino geometry

    Science.gov (United States)

    Schmidt, Benjamin; Bennaceur, Keyan; Bilodeau, Simon; Gaucher, Samuel; Lilly, Michael; Reno, John; Pfeiffer, Loren; West, Ken; Reulet, Bertrand; Gervais, Guillaume

    We present two- and four-point Corbino geometry transport measurements in the second Landau level in GaAs/AlGaAs heterostructures. By avoiding edge transport, we are able to directly probe the physics of the bulk quasiparticles in fractional quantum Hall (FQH) states including 5/2. Our highest-quality sample shows stripe and bubble phases in high Landau levels, and most importantly well-resolved FQH minima in the second Landau level. We report Arrhenius-type fits to the activated conductance, and find that σ0 agrees well with theory and existing Hall geometry data in the first Landau level, but not in the second Landau level. We will discuss the advantages the Corbino geometry could bring to various experiments designed to detect the non-Abelian entropy at 5/2, and our progress towards realizing those schemes. The results of these experiments could complement interferometry and other edge-based measurements by providing direct evidence for non-Abelian behaviour of the bulk quasiparticles. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL8500.

  12. Robust control problems of vortex dynamics in superconducting films with Ginzburg-Landau complex systems

    OpenAIRE

    Belmiloudi, Aziz

    2006-01-01

    We formulate and study robust control problems for a two-dimensional time-dependent Ginzburg-Landau model with Robin boundary conditions on phase-field parameter, which describes the phase transitions taking place in superconductor films with variable thickness. The objective of such study is to control the motion of vortices in the superconductor films by taking into account the influence of noises in data. Firstly, we introduce the perturbation problem of the nonlinear ...

  13. Need for reaction coordinates to ensure a complete basis set in an adiabatic representation of ion-atom collisions

    Science.gov (United States)

    Rabli, Djamal; McCarroll, Ronald

    2018-02-01

    This review surveys the different theoretical approaches, used to describe inelastic and rearrangement processes in collisions involving atoms and ions. For a range of energies from a few meV up to about 1 keV, the adiabatic representation is expected to be valid and under these conditions, inelastic and rearrangement processes take place via a network of avoided crossings of the potential energy curves of the collision system. In general, such avoided crossings are finite in number. The non-adiabatic coupling, due to the breakdown of the Born-Oppenheimer separation of the electronic and nuclear variables, depends on the ratio of the electron mass to the nuclear mass terms in the total Hamiltonian. By limiting terms in the total Hamiltonian correct to first order in the electron to nuclear mass ratio, a system of reaction coordinates is found which allows for a correct description of both inelastic channels. The connection between the use of reaction coordinates in the quantum description and the electron translation factors of the impact parameter approach is established. A major result is that only when reaction coordinates are used, is it possible to introduce the notion of a minimal basis set. Such a set must include all avoided crossings including both radial coupling and long range Coriolis coupling. But, only when reactive coordinates are used, can such a basis set be considered as complete. In particular when the centre of nuclear mass is used as centre of coordinates, rather than the correct reaction coordinates, it is shown that erroneous results are obtained. A few results to illustrate this important point are presented: one concerning a simple two-state Landau-Zener type avoided crossing, the other concerning a network of multiple crossings in a typical electron capture process involving a highly charged ion with a neutral atom.

  14. The Effects of Nuclear Weapons. Third edition

    Energy Technology Data Exchange (ETDEWEB)

    Glasstone, S; Dolan, P J

    1977-01-01

    Since the last edition of ''The Effects of Nuclear Weapons'' in 1962 much new information has become available concerning nuclear weapon effects. This has come in part from the series of atmospheric tests, including several at very high altitudes, conducted in the Pacific Ocean area in 1962. In addition, laboratory studies, theoretical calculations, and computer simulations have provided a better understanding of the various effects. A new chapter has been added on the electromagnetic pulse. The chapter titles are as follows: general principles of nuclear explosions; descriptions of nuclear explosions; air blast phenomena in air and surface bursts; air blast loading; structural damage from air blast; shock effects of surface and subsurface bursts; thermal radiation and its effects; initial nuclear radiation; residual nuclear radiation and fallout; radio and radar effects; the electromagnetic pulse and its effects; and biological effects. (LTN)

  15. Noise-sustained structure, Intermittency, and the Ginzburg--Landau equation

    International Nuclear Information System (INIS)

    Deissler, R.J.

    1985-01-01

    The time-dependent generalized Ginzburg--Landau equation is an equation that is related to many physical systems. Solutions of this equation in the presence of low-level external noise are studied. Numerical solutions of this equation in the stationary frame of refernce and with nonzero group velocity that is greater than a critical velocity exhibit a selective spatial amplification of noise resulting in spatially growing waves. These waves in turn result in the formation of a dynamic structure. It is found that the microscopic noise plays an importuant role in the macroscopic dynamics of the system. For certain parameter values the system exhibits intermittent turbulent behavior in which the random nature of the external noise plays a crucial role. A mechanism which may be responsible for the intermittent turbulence occurring in some fluid systems is suggested

  16. Composite Fermi surface in the half-filled Landau level with anisotropic electron mass

    Science.gov (United States)

    Ippoliti, Matteo; Geraedts, Scott; Bhatt, Ravindra

    We study the problem of interacting electrons in the lowest Landau level at half filling in the quantum Hall regime, when the electron dispersion is given by an anisotropic mass tensor. Based on experimental observations and theoretical arguments, the ground state of the system is expected to consist of composite Fermions filling an elliptical Fermi sea, with the anisotropy of the ellipse determined by the competing effects of the isotropic Coulomb interaction and anisotropic electron mass tensor. We test this idea quantitatively by using a numerical density matrix renormalization group method for quantum Hall systems on an infinitely long cylinder. Singularities in the structure factor allow us to map the Fermi surface of the composite Fermions. We compute the composite Fermi surface anisotropy for several values of the electron mass anisotropy which allow us to deduce the functional dependence of the former on the latter. This research was supported by Department of Energy Office of Basic Energy Sciences through Grant No. DE-SC0002140.

  17. Topological Landau-Ginzburg theory with a rational potential and the dispersionless KP hierarchy

    International Nuclear Information System (INIS)

    Aoyama, S.; Kodama, Y.

    1996-01-01

    Based on the dispersionless KP (dKP) theory, we study a topological Landau-Ginzburg (LG) theory characterized by a rational potential. Writing the dKP hierarchy in a general form treating all the primaries in an equal basis, we find that the hierarchy naturally includes the dispersionless (continuous) limit of Toda hierarchy and its generalizations having a finite number of primaries. Several flat solutions of the topological LG theory are obtained in this formulation, and are identified with those discussed by Dubrovin. We explicitly construct gravitational descendants for all the primary fields. Giving a residue formula for the 3-point functions of the fields, we show that these 3-point functions satisfy the topological recursion relation. The string equation is obtained as the generalized hodograph solutions of the dKP hierarchy, which show that all the gravitational effects to the constitutive equations (2-point functions) can be renormalized into the coupling constants in the small phase space. (orig.)

  18. Psychological effects of nuclear warfare

    International Nuclear Information System (INIS)

    Mickley, G.A.

    1987-01-01

    This report is divided into five parts. (1) Discussion of the psychological milieu before a nuclear confrontation. (2) Acute psychological reactions to nuclear warfare (some of which may reflect, in part, direct radiogenic alteration of nervous system functions). (3) Chronic psychological effects of a nuclear confrontation. (4) Issues concerning treatment of these psychological changes. (5) Prevention of adverse psychological reactions to nuclear warfare

  19. Spatially Localized Particle Energization by Landau Damping in Current Sheets

    Science.gov (United States)

    Howes, G. G.; Klein, K. G.; McCubbin, A. J.

    2017-12-01

    Understanding the mechanisms of particle energization through the removal of energy from turbulent fluctuations in heliospheric plasmas is a grand challenge problem in heliophysics. Under the weakly collisional conditions typical of heliospheric plasma, kinetic mechanisms must be responsible for this energization, but the nature of those mechanisms remains elusive. In recent years, the spatial localization of plasma heating near current sheets in the solar wind and numerical simulations has gained much attention. Here we show, using the innovative and new field-particle correlation technique, that the spatially localized particle energization occurring in a nonlinear gyrokinetic simulation has the velocity space signature of Landau damping, suggesting that this well-known collisionless damping mechanism indeed actively leads to spatially localized heating in the vicinity of current sheets.

  20. Evidence of tensor correlations in the nuclear many-body system using a modern NN potential

    International Nuclear Information System (INIS)

    Fiase, J.O.; Nkoma, J.S.; Sharmaand, L.K.; Hosaka, A.

    2003-01-01

    In this paper we show evidence of the importance of tensor correlations in the nuclear many-body system by calculating the effective two-body nuclear matrix elements in the frame work of the Lowest-Order Constrained Variational (LOCV) technique with two-body correlation functions using the Reid93 potential. We have achieved this by switching on and off the strength of the tensor correlations, α k . We have found that in order to obtain reasonable agreement with earlier calculations based on the G-matrix theory, we must turn on the strength of the tensor correlations especially in the triplet even (TE) and tensor even (TNE) channels to take the value of approximately, 0.05. As an application, we have estimated the value of the Landau - Migdal parameter, g' NN which we found to be g' NN = 0.65. This compares favorably with the G-matrix calculated value of g' NN = 0.54. (author)

  1. The nuclear flow and the mass number dependence of the balance point

    International Nuclear Information System (INIS)

    Sebille, F.; de la Mota, V.; Remaud, B.; Schuck, P.

    1990-01-01

    The nuclear flow is studied theoretically with the Landau Vlasov equation in the E/A = 50 to 150 MeV energy domain using the finite range Gogny force. For comparison also other equations of states based on velocity independent mean fields are used. In this paper the mass number dependence of the balance point is investigated. A sensitivity of the flow on the equation of state as a function of mass and energies around and above the balance point can tentatively be advanced

  2. Landau levels in biased graphene structures with monolayer-bilayer interfaces

    Science.gov (United States)

    Mirzakhani, M.; Zarenia, M.; Vasilopoulos, P.; Ketabi, S. A.; Peeters, F. M.

    2017-09-01

    The electron energy spectrum in monolayer-bilayer-monolayer and in bilayer-monolayer-bilayer graphene structures is investigated and the effects of a perpendicular magnetic field and electric bias are studied. Different types of monolayer-bilayer interfaces are considered as zigzag (ZZ) or armchair (AC) junctions which modify considerably the bulk Landau levels (LLs) when the spectra are plotted as a function of the center coordinate of the cyclotron orbit. Far away from the two interfaces, one obtains the well-known LLs for extended monolayer or bilayer graphene. The LL structure changes significantly at the two interfaces or junctions where the valley degeneracy is lifted for both types of junctions, especially when the distance between them is approximately equal to the magnetic length. Varying the nonuniform bias and the width of this junction-to-junction region in either structure strongly influence the resulting spectra. Significant differences exist between ZZ and AC junctions in both structures. The densities of states (DOSs) for unbiased structures are symmetric in energy whereas those for biased structures are asymmetric. An external bias creates interface LLs in the gaps between the LLs of the unbiased system in which the DOS can be quite small. Such a pattern of LLs can be probed by scanning tunneling microscopy.

  3. Advances in the simulation of toroidal gyro Landau fluid model turbulence

    International Nuclear Information System (INIS)

    Waltz, R.E.; Kerbel, G.D.; Milovich, J.; Hammett, G.W.

    1994-12-01

    The gyro-Landau fluid (GLF) model equations for toroidal geometry have been recently applied to the study ion temperature gradient (ITG) mode turbulence using the 3D nonlinear ballooning mode representation (BMR). The present paper extends this work by treating some unresolved issues conceming ITG turbulence with adiabatic electrons. Although eddies are highly elongated in the radial direction long time radial correlation lengths are short and comparable to poloidal lengths. Although transport at vanishing shear is not particularly large, transport at reverse global shear, is significantly less. Electrostatic transport at moderate shear is not much effected by inclusion of local shear and average favorable curvature. Transport is suppressed when critical ExB rotational shear is comparable to the maximum linear growth rate with only a weak dependence on magnetic shear. Self consistent turbulent transport of toroidal momentum can result in a transport bifurcation at suffciently large r/(Rq). However the main thrust of the new formulation in the paper deals with advances in the development of finite beta GLF models with trapped electron and BMR numerical methods for treating the fast parallel field motion of the untrapped electrons

  4. Biological effects of nuclear weapons

    International Nuclear Information System (INIS)

    Frischauf, H.

    1983-01-01

    Prompt and delayed biological effects of nuclear weapons are discussed. The response to excess pressure on man is estimated, the acute radiation syndrome caused by different radiation doses and cancerogenous and genetic effects are described. Medical care after a nuclear explosion would be difficult and imperfect. (M.J.)

  5. Effect of the Fukushima nuclear disaster on global public acceptance of nuclear energy

    International Nuclear Information System (INIS)

    Kim, Younghwan; Kim, Minki; Kim, Wonjoon

    2013-01-01

    The Fukushima nuclear disaster has significantly changed public attitudes toward nuclear energy. It is important to understand how this change has occurred in different countries before the global community revises existing nuclear policies. This study examines the effect of the Fukushima disaster on public acceptance of nuclear energy in 42 countries. We find that the operational experience of nuclear power generation which has significantly affected positive public opinion about nuclear energy became considerably negative after the disaster, suggesting fundamental changes in public acceptance regardless of the level of acceptance before the disaster. In addition, contrary to our expectation, the proportion of nuclear power generation is positively and significantly related to public acceptance of nuclear energy after the Fukushima accident and government pressure on media content led to a greater decrease in the level of public acceptance after the accident. Nuclear energy policymakers should consider the varied factors affecting public acceptance of nuclear energy in each country depending on its historical, environmental, and geographical circumstances before they revise nuclear policy in response to the Fukushima accident. - Highlights: • Fukushima accident has negatively changed public attitudes toward nuclear energy. • Effect of operational experience became considerably negative after the accident. • Effect of proportion of nuclear power generation is positive after the accident. • Effect of government pressure on media content became negative after the accident. • Country specific policy responses on nuclear public acceptance are required

  6. Symmetry breaking in Landau gauge. A comment to a paper by T. Kennedy and C. King

    International Nuclear Information System (INIS)

    Borgs, C.; Nill, F.

    1986-01-01

    The authors generalize the result of T. Kennedy and C. King (Princeton preprint, 1985) on the non-compact abelian lattice Higgs model in Landau gauge in order to show that there are states parameterized by an angle such that the expectation value of the Higgs field is described by a phase factor and a value which is uniformly bounded away from zero. (HSI)

  7. Large spin limits of AdS/CFT and generalized Landau-Lifshitz equations

    International Nuclear Information System (INIS)

    Stefanski, B. Jr.; Tseytlin, A.A.

    2004-01-01

    We consider AdS 5 x S 5 string states with several large angular momenta along AdS 5 and S 5 directions which are dual to single-trace Super-Yang-Mills (SYM) operators built out of chiral combinations of scalars and covariant derivatives. In particular, we focus on the SU(3) sector (with three spins in S 5 ) and the SL(2) sector (with one spin in AdS 5 and one in S 5 ), generalizing recent work hep-th/0311203 and hep-th/0403120 on the SU(2) sector with two spins in S 5 . We show that, in the large spin limit and at the leading order in the effective coupling expansion, the string sigma model equations of motion reduce to matrix Landau-Lifshitz equations. We then demonstrate that the coherent-state expectation value of the one-loop SYM dilatation operator restricted to the corresponding sector of single trace operators is also effectively described by the same equations. This implies a universal leading order equivalence between string energies and SYM anomalous dimensions, as well as a matching of integrable structures. We also discuss the more general 5-spin sector and comment on SO(6) states dual to non-chiral scalar operators. (author)

  8. Martensitic phase transformations in Ni–Ti-based shape memory alloys: The Landau theory

    International Nuclear Information System (INIS)

    Shchyglo, Oleg; Salman, Umut; Finel, Alphonse

    2012-01-01

    We present a simple Landau free energy functional for cubic-to-orthorhombic and cubic-to-monoclinic martensitic phase transformations. The functional is derived following group–subgroup relations between different martensitic phases – tetragonal, trigonal, orthorhombic and monoclinic – in order to fully capture the symmetry properties of the free energy of the austenite and martensite phases. The derived free energy functional is fitted to the elastic and thermodynamic properties of NiTi and NiTiCu shape memory alloys which exhibit cubic-to-monoclinic and cubic-to-orthorhombic martensitic phase transformations, respectively.

  9. Landau quantized dynamics and spectra for group-VI dichalcogenides, including a model quantum wire

    Science.gov (United States)

    Horing, Norman J. M.

    2017-06-01

    This work is concerned with the derivation of the Green's function for Landau-quantized carriers in the Group-VI dichalcogenides. In the spatially homogeneous case, the Green's function is separated into a Peierls phase factor and a translationally invariant part which is determined in a closed form integral representation involving only elementary functions. The latter is expanded in an eigenfunction series of Laguerre polynomials. These results for the retarded Green's function are presented in both position and momentum representations, and yet another closed form representation is derived in circular coordinates in terms of the Bessel wave function of the second kind (not to be confused with the Bessel function). The case of a quantum wire is also addressed, representing the quantum wire in terms of a model one-dimensional δ (x ) -potential profile. This retarded Green's function for propagation directly along the wire is determined exactly in terms of the corresponding Green's function for the system without the δ (x ) -potential, and the Landau quantized eigenenergy dispersion relation is examined. The thermodynamic Green's function for the dichalcogenide carriers in a normal magnetic field is formulated here in terms of its spectral weight, and its solution is presented in a momentum/integral representation involving only elementary functions, which is subsequently expanded in Laguerre eigenfunctions and presented in both momentum and position representations.

  10. Landau quantized dynamics and spectra for group-VI dichalcogenides, including a model quantum wire

    Directory of Open Access Journals (Sweden)

    Norman J. M. Horing

    2017-06-01

    Full Text Available This work is concerned with the derivation of the Green’s function for Landau-quantized carriers in the Group-VI dichalcogenides. In the spatially homogeneous case, the Green’s function is separated into a Peierls phase factor and a translationally invariant part which is determined in a closed form integral representation involving only elementary functions. The latter is expanded in an eigenfunction series of Laguerre polynomials. These results for the retarded Green’s function are presented in both position and momentum representations, and yet another closed form representation is derived in circular coordinates in terms of the Bessel wave function of the second kind (not to be confused with the Bessel function. The case of a quantum wire is also addressed, representing the quantum wire in terms of a model one-dimensional δ(x-potential profile. This retarded Green’s function for propagation directly along the wire is determined exactly in terms of the corresponding Green’s function for the system without the δ(x-potential, and the Landau quantized eigenenergy dispersion relation is examined. The thermodynamic Green’s function for the dichalcogenide carriers in a normal magnetic field is formulated here in terms of its spectral weight, and its solution is presented in a momentum/integral representation involving only elementary functions, which is subsequently expanded in Laguerre eigenfunctions and presented in both momentum and position representations.

  11. Nuclear threshold effects and neutron strength function

    International Nuclear Information System (INIS)

    Hategan, Cornel; Comisel, Horia

    2003-01-01

    One proves that a Nuclear Threshold Effect is dependent, via Neutron Strength Function, on Spectroscopy of Ancestral Neutron Threshold State. The magnitude of the Nuclear Threshold Effect is proportional to the Neutron Strength Function. Evidence for relation of Nuclear Threshold Effects to Neutron Strength Functions is obtained from Isotopic Threshold Effect and Deuteron Stripping Threshold Anomaly. The empirical and computational analysis of the Isotopic Threshold Effect and of the Deuteron Stripping Threshold Anomaly demonstrate their close relationship to Neutron Strength Functions. It was established that the Nuclear Threshold Effects depend, in addition to genuine Nuclear Reaction Mechanisms, on Spectroscopy of (Ancestral) Neutron Threshold State. The magnitude of the effect is proportional to the Neutron Strength Function, in their dependence on mass number. This result constitutes also a proof that the origins of these threshold effects are Neutron Single Particle States at zero energy. (author)

  12. Disordered λ φ4+ρ φ6 Landau-Ginzburg model

    Science.gov (United States)

    Diaz, R. Acosta; Svaiter, N. F.; Krein, G.; Zarro, C. A. D.

    2018-03-01

    We discuss a disordered λ φ4+ρ φ6 Landau-Ginzburg model defined in a d -dimensional space. First we adopt the standard procedure of averaging the disorder-dependent free energy of the model. The dominant contribution to this quantity is represented by a series of the replica partition functions of the system. Next, using the replica-symmetry ansatz in the saddle-point equations, we prove that the average free energy represents a system with multiple ground states with different order parameters. For low temperatures we show the presence of metastable equilibrium states for some replica fields for a range of values of the physical parameters. Finally, going beyond the mean-field approximation, the one-loop renormalization of this model is performed, in the leading-order replica partition function.

  13. Quasi-linear landau kinetic equations for magnetized plasmas: compact propagator formalism, rotation matrices and interaction

    International Nuclear Information System (INIS)

    Misguich, J.H.

    2004-04-01

    As a first step toward a nonlinear renormalized description of turbulence phenomena in magnetized plasmas, the lowest order quasi-linear description is presented here from a unified point of view for collisionless as well as for collisional plasmas in a constant magnetic field. The quasi-linear approximation is applied to a general kinetic equation obtained previously from the Klimontovich exact equation, by means of a generalised Dupree-Weinstock method. The so-obtained quasi-linear description of electromagnetic turbulence in a magnetoplasma is applied to three separate physical cases: -) weak electrostatic turbulence, -) purely magnetic field fluctuations (the classical quasi-linear results are obtained for cosmic ray diffusion in the 'slab model' of magnetostatic turbulence in the solar wind), and -) collisional kinetic equations of magnetized plasmas. This mathematical technique has allowed us to derive basic kinetic equations for turbulent plasmas and collisional plasmas, respectively in the quasi-linear and Landau approximation. In presence of a magnetic field we have shown that the systematic use of rotation matrices describing the helical particle motion allows for a much more compact derivation than usually performed. Moreover, from the formal analogy between turbulent and collisional plasmas, the results derived here in detail for the turbulent plasmas, can be immediately translated to obtain explicit results for the Landau kinetic equation

  14. Quasi-linear landau kinetic equations for magnetized plasmas: compact propagator formalism, rotation matrices and interaction

    Energy Technology Data Exchange (ETDEWEB)

    Misguich, J.H

    2004-04-01

    As a first step toward a nonlinear renormalized description of turbulence phenomena in magnetized plasmas, the lowest order quasi-linear description is presented here from a unified point of view for collisionless as well as for collisional plasmas in a constant magnetic field. The quasi-linear approximation is applied to a general kinetic equation obtained previously from the Klimontovich exact equation, by means of a generalised Dupree-Weinstock method. The so-obtained quasi-linear description of electromagnetic turbulence in a magnetoplasma is applied to three separate physical cases: -) weak electrostatic turbulence, -) purely magnetic field fluctuations (the classical quasi-linear results are obtained for cosmic ray diffusion in the 'slab model' of magnetostatic turbulence in the solar wind), and -) collisional kinetic equations of magnetized plasmas. This mathematical technique has allowed us to derive basic kinetic equations for turbulent plasmas and collisional plasmas, respectively in the quasi-linear and Landau approximation. In presence of a magnetic field we have shown that the systematic use of rotation matrices describing the helical particle motion allows for a much more compact derivation than usually performed. Moreover, from the formal analogy between turbulent and collisional plasmas, the results derived here in detail for the turbulent plasmas, can be immediately translated to obtain explicit results for the Landau kinetic equation.

  15. Analytic treatments of matter-enhanced solar-neutrino oscillations

    International Nuclear Information System (INIS)

    Haxton, W.C.

    1987-01-01

    Mikheyev and Smirnov have pointed out that flavor oscillations of solar neutrinos could be greatly enhanced. The Mikheyev-Smirnov-Wolfenstein mechanism depends on the effective electron neutrino mass that arises from charged-current scattering off solar electrons, a phenomenon first discussed by Wolfenstein. Two analytic treatments, the adiabatic approximation and Landau-Zener (LZ) approximation, have been used in studies of this mechanism. I discuss a simple extension of the LZ approximation that merges naturally with the adiabatic approximation and is free of certain troublesome pathologies that arise in the conventional treatment. In this extension the solar density is approximated as in the conventional treatment, except that the starting and ending densities are the physical ones. Results of this finite LZ approximation are compared to those from the standard LZ approximation, the adiabatic approximation, and ''exact'' numerical integrations. The new approximation is virtually exact regardless of the point of origin of the neutrino in the solar core. This approximation is used to efficiently calculate the solar-neutrino capture rates for /sup 37/Cl, /sup 71/Ga, and /sup 98/Mo. The spatial extent of the solar core, the contributions of minor neutrino species, and the effects of 8 B neutrino capture to excited nuclear states are treated with care. Limits imposed on δm 2 and sin 2 2theta/sub v/ by the nonzero /sup 37/Cl capture rate are derived by considering the expected uncertainties in standard-solar-model flux estimates. Those oscillation parameters are determined that could account for the /sup 37/Cl puzzle and yet lead to a /sup 71/Ga counting rate above the minimum astronomical value

  16. The nuclear response function

    International Nuclear Information System (INIS)

    Bertsch, G.F.

    1983-01-01

    These lectures present the theory of the nuclear response in the Random Phase Approximation (RPA). In the first lecture, various relations are derived between densities and currents which give rise to the well-known sum rules. Then RPA is derived via the time-dependent Hartree theory. The various formulations of RPA are shown: the configuration space representation, the coordinate space representation, the Landau theory of infinite systems and the RPA for separable interactions constrained by consistency. The remarkable success of RPA in describing the collective density oscillations of closed shell nuclei is illustrated with a few examples. In the final lecture, the σtau response is discussed with the application of simple theoretical considerations to the empirical data. Finally, we point out several problems which remain in the response theory. (author)

  17. The Characteristics of an Effective Nuclear Regulator

    International Nuclear Information System (INIS)

    Cheok, Michael; Wertelaers, An; Lojk, Robert; Santini, Miguel; Alm-Lytz, Kirsi; Rigail, Anne-Cecile; Weidenbruck, Kai-Jochen; Stoppa, Gisela; Rainieri, Roberto; Aoki, Masahiro; Gonzalez-Mercado; Miroshnichenko, Mikhail; Kuznetsov, Nikolay; Kudryavtsev, Evgeny; Cid, Rafael; Franzen, Anna; Skanberg, Lars; Gibson, Steve; Golshan, Mina; Cheok, Michael; Nicic, Adriana; Salgado, Nancy; Creswell, Len

    2014-01-01

    Both national and international organisations agree that the fundamental objective of all nuclear safety regulatory bodies - the regulator's prime purpose - is to ensure that nuclear licensees operate their facilities at all times in a safe manner. Much has been written about ways to improve regulatory processes or to improve the effectiveness of a regulatory body, including in previous OECD/NEA regulatory guidance booklets. But until now, none have focused on the characteristics of an effective nuclear safety regulator. Effective organisations are those that have good leadership and are able to transform strategic direction into operational programmes. Effectiveness is about how well the organisation is achieving its fundamental purpose - in the case of a nuclear safety regulator, ensuring that licensees operate their facilities and discharge their obligations in a safe manner. This regulatory guidance booklet describes the characteristics of an effective nuclear safety regulator in terms of roles and responsibilities, principles and attributes. Each of the characteristics discussed in this report is a necessary feature of an effective nuclear safety regulator but no one characteristic is sufficient on its own. It is the combination of these characteristics that leads to the effectiveness of a nuclear regulatory body. The report provides a unique resource to countries with existing, mature regulators and can be used for benchmarking as well as training and developing staff. It will also be useful for new entrant countries in the process of developing and maintaining an effective nuclear safety regulator. (authors)

  18. Thermoelectric Transport Signatures of Dirac Composite Fermions in the Half-Filled Landau Level

    Science.gov (United States)

    Potter, Andrew C.; Serbyn, Maksym; Vishwanath, Ashvin

    2016-07-01

    The half-filled Landau level is expected to be approximately particle-hole symmetric, which requires an extension of the Halperin-Lee-Read (HLR) theory of the compressible state observed at this filling. Recent work indicates that, when particle-hole symmetry is preserved, the composite fermions experience a quantized π -Berry phase upon winding around the composite Fermi surface, analogous to Dirac fermions at the surface of a 3D topological insulator. In contrast, the effective low-energy theory of the composite fermion liquid originally proposed by HLR lacks particle-hole symmetry and has vanishing Berry phase. In this paper, we explain how thermoelectric transport measurements can be used to test the Dirac nature of the composite fermions by quantitatively extracting this Berry phase. First, we point out that longitudinal thermopower (Seebeck effect) is nonvanishing because of the unusual nature of particle-hole symmetry in this context and is not sensitive to the Berry phase. In contrast, we find that off-diagonal thermopower (Nernst effect) is directly related to the topological structure of the composite Fermi surface, vanishing for zero Berry phase and taking its maximal value for π Berry phase. In contrast, in purely electrical transport signatures, the Berry phase contributions appear as small corrections to a large background signal, making the Nernst effect a promising diagnostic of the Dirac nature of composite fermions.

  19. Quark effects in nuclear physics

    International Nuclear Information System (INIS)

    Miller, G.A.

    1983-01-01

    A phenomenological approach which enables the size of quark effects in various nuclear processes is discussed. The principle of conservation of probability provides significant constraints on six quark wave functions. Using this approach, it is found that the low-energy proton-proton weak interaction can be explained in terms of W and Z boson exchanges between quarks. That the value of the asymptotic ratio of D to S state wave functions is influenced (at the 5% level) by quark effects, is another result of our approach. We have not discovered a nuclear effect that can be uniquely explained by quark-quark interactions. However it does seem that quark physics is very relevant for nuclear physics. 52 references

  20. Convergence of high order memory kernels in the Nakajima-Zwanzig generalized master equation and rate constants: Case study of the spin-boson model

    Science.gov (United States)

    Xu, Meng; Yan, Yaming; Liu, Yanying; Shi, Qiang

    2018-04-01

    The Nakajima-Zwanzig generalized master equation provides a formally exact framework to simulate quantum dynamics in condensed phases. Yet, the exact memory kernel is hard to obtain and calculations based on perturbative expansions are often employed. By using the spin-boson model as an example, we assess the convergence of high order memory kernels in the Nakajima-Zwanzig generalized master equation. The exact memory kernels are calculated by combining the hierarchical equation of motion approach and the Dyson expansion of the exact memory kernel. High order expansions of the memory kernels are obtained by extending our previous work to calculate perturbative expansions of open system quantum dynamics [M. Xu et al., J. Chem. Phys. 146, 064102 (2017)]. It is found that the high order expansions do not necessarily converge in certain parameter regimes where the exact kernel show a long memory time, especially in cases of slow bath, weak system-bath coupling, and low temperature. Effectiveness of the Padé and Landau-Zener resummation approaches is tested, and the convergence of higher order rate constants beyond Fermi's golden rule is investigated.

  1. Phase-field model of insulator-to-metal transition in VO2 under an electric field

    Science.gov (United States)

    Shi, Yin; Chen, Long-Qing

    2018-05-01

    The roles of an electric field and electronic doping in insulator-to-metal transitions are still not well understood. Here we formulated a phase-field model of insulator-to-metal transitions by taking into account both structural and electronic instabilities as well as free electrons and holes in VO2, a strongly correlated transition-metal oxide. Our phase-field simulations demonstrate that in a VO2 slab under a uniform electric field, an abrupt universal resistive transition occurs inside the supercooling region, in sharp contrast to the conventional Landau-Zener smooth electric breakdown. We also show that hole doping may decouple the structural and electronic phase transitions in VO2, leading to a metastable metallic monoclinic phase which could be stabilized through a geometrical confinement and the size effect. This work provides a general mesoscale thermodynamic framework for understanding the influences of electric field, electronic doping, and stress and strain on insulator-to-metal transitions and the corresponding mesoscale domain structure evolution in VO2 and related strongly correlated systems.

  2. Strengthened International Nuclear Safeguards; burdens and Effects on Nuclear Technology Development

    International Nuclear Information System (INIS)

    Badawy, I.

    2000-01-01

    The present paper deals with the recent direction of strengthening the international nuclear safeguards and the effects on the development of nuclear technology for peaceful applications. The new basic principles for strengthening the international nuclear control in the direction of undeclared nuclear activities are elaborated, and the national obligations are indicated. The burdens on the development of nuclear technology are discussed. Approaches are proposed in this work for coping with the present and future situations

  3. Axion production from Landau quantization in the strong magnetic field of magnetars

    Science.gov (United States)

    Maruyama, Tomoyuki; Balantekin, A. Baha; Cheoun, Myung-Ki; Kajino, Toshitaka; Mathews, Grant J.

    2018-04-01

    We utilize an exact quantum calculation to explore axion emission from electrons and protons in the presence of the strong magnetic field of magnetars. The axion is emitted via transitions between the Landau levels generated by the strong magnetic field. The luminosity of axions emitted by protons is shown to be much larger than that of electrons and becomes stronger with increasing matter density. Cooling by axion emission is shown to be much larger than neutrino cooling by the Urca processes. Consequently, axion emission in the crust may significantly contribute to the cooling of magnetars. In the high-density core, however, it may cause heating of the magnetar.

  4. Skyrme interaction to second order in nuclear matter

    Science.gov (United States)

    Kaiser, N.

    2015-09-01

    Based on the phenomenological Skyrme interaction various density-dependent nuclear matter quantities are calculated up to second order in many-body perturbation theory. The spin-orbit term as well as two tensor terms contribute at second order to the energy per particle. The simultaneous calculation of the isotropic Fermi-liquid parameters provides a rigorous check through the validity of the Landau relations. It is found that published results for these second order contributions are incorrect in most cases. In particular, interference terms between s-wave and p-wave components of the interaction can contribute only to (isospin or spin) asymmetry energies. Even with nine adjustable parameters, one does not obtain a good description of the empirical nuclear matter saturation curve in the low density region 0\\lt ρ \\lt 2{ρ }0. The reason for this feature is the too strong density-dependence {ρ }8/3 of several second-order contributions. The inclusion of the density-dependent term \\frac{1}{6}{t}3{ρ }1/6 is therefore indispensable for a realistic description of nuclear matter in the Skyrme framework.

  5. The Effects of Nuclear Weapons

    Energy Technology Data Exchange (ETDEWEB)

    Glasstone, Samuel

    1964-02-01

    This book is a revision of "The Effects of Nuclear Weapons" which was issued in 1957. It was prepared by the Defense Atomic Support Agency of the Department of Defense in coordination with other cognizant governmental agencies and was published by the U.S. Atomc Energy Commission. Although the complex nature of nuclear weapons effects does not always allow exact evaluation, the conclusions reached herein represent the combined judgment of a number of the most competent scientists working the problem. There is a need for widespread public understanding of the best information available on the effects of nuclear weapons. The purpose of this book is to present as accurately as possible, within the limits of national security, a comprehensive summary of this information.

  6. Nuclear energy: biological effects and environmental impact

    International Nuclear Information System (INIS)

    Boonefaes, M.

    1987-01-01

    This thesis is concerned with the large development of nuclear power plants and the recent nuclear catastrophe which has made clear how the hazards resulting from radioactivity affect public health and the environment. Environmental effects of nuclear power plants operating in normal conditions are small, but to obtain nuclear power plants of reduced radioactivity, optimization of their design, construction, operation and waste processing plays a decisive role. Biological effects of ionizing radiations and environmental impacts of Nuclear Power plants are developed [fr

  7. Generalized shortcuts to adiabaticity and enhanced robustness against decoherence

    Science.gov (United States)

    Santos, Alan C.; Sarandy, Marcelo S.

    2018-01-01

    Shortcuts to adiabaticity provide a general approach to mimic adiabatic quantum processes via arbitrarily fast evolutions in Hilbert space. For these counter-diabatic evolutions, higher speed comes at higher energy cost. Here, the counter-diabatic theory is employed as a minimal energy demanding scheme for speeding up adiabatic tasks. As a by-product, we show that this approach can be used to obtain infinite classes of transitionless models, including time-independent Hamiltonians under certain conditions over the eigenstates of the original Hamiltonian. We apply these results to investigate shortcuts to adiabaticity in decohering environments by introducing the requirement of a fixed energy resource. In this scenario, we show that generalized transitionless evolutions can be more robust against decoherence than their adiabatic counterparts. We illustrate this enhanced robustness both for the Landau-Zener model and for quantum gate Hamiltonians.

  8. Low energy electron capture in collisions of C3+ with He

    International Nuclear Information System (INIS)

    Wu, Y.; Qi, Y.Y.; Yan, J.; Wang, J.G.; Li, Y.; Buenker, R.J.; Kato, D.

    2009-06-01

    Charge transfer processes due to collisions of ground state C 3+ (1s 2 2s 2 S) ions with He atom are investigated using the quantum-mechanical molecular-orbital close-coupling (QMOCC) method for energies between 10 -4 eV/u and 10 3 eV/u. The ab initio adiabatic potential and radial coupling utilized in the QMOCC calculations are obtained from the multi-reference single- and double-excitation configuration interaction (MRD-CI) approach. Total and state-selective single electron capture (SEC) cross sections and rate coefficients are obtained and compared with the available experimental and theoretical data. Good agreement between the measured SEC cross sections and the present calculation is found, but the previous calculation of total rate coefficient using the Landau-Zener model is one or two orders of magnitude smaller than the present result. (author)

  9. Endoergic chemi-ionization in N-O collisions

    International Nuclear Information System (INIS)

    Nielsen, S.E.; Dahler, J.S.

    1979-01-01

    A semiclassical theory of endoergic chemi-ionization is developed and applied to the ionizing events that occur when ground state oxygen atoms collide with nitrogen atoms in the ground and first excited states. The approach used is an adaptation and extension of earlier theories due to Bardsley, Nakamura, and Miller. The theory relates the experimental associative (AI) and Penning ionization (PI) cross sections to the following events: formation of a stable diatomic ion (AI), neutral and ionized atomic fragments (PI), or of a metastable diatomic rotational resonance (DI, delayed ionization). The heavy particle motions are treated classically in terms of adiabatic potential energy functions, while localized nonadiabatic transitions also are taken into account by using the Landau-Zener approximation. Finally, the theoretical predictions compare well with the results of Ringer and Gentry's (1978) merged beam experiments

  10. Nanostructured Fe-Cr Alloys for Advanced Nuclear Energy Applications

    Energy Technology Data Exchange (ETDEWEB)

    Scattergood, Ronald O. [North Carolina State Univ., Raleigh, NC (United States)

    2016-04-26

    We have completed research on the grain-size stabilization of model nanostructured Fe14Cr base alloys at high temperatures by the addition of non-equilibrium solutes. Fe14Cr base alloys are representative for nuclear reactor applications. The neutron flux in a nuclear reactor will generate He atoms that coalesce to form He bubbles. These can lead to premature failure of the reactor components, limiting their lifetime and increasing the cost and capacity for power generation. In order to mitigate such failures, Fe14Cr base alloys have been processed to contain very small nano-size oxide particles (less than 10 nm in size) that trap He atoms and reduce bubble formation. Theoretical and experimental results indicate that the grain boundaries can also be very effective traps for He atoms and bubble formation. An optimum grain size will be less than 100 nm, ie., nanocrystalline alloys must be used. Powder metallurgy methods based on high-energy ball milling can produce Fe-Cr base nanocrystalline alloys that are suitable for nuclear energy applications. The problem with nanocrystalline alloys is that excess grain-boundary energy will cause grains to grow at higher temperatures and their propensity for He trapping will be lost. The nano-size oxide particles in current generation nuclear alloys provide some grain size stabilization by reducing grain-boundary mobility (Zener pinning – a kinetic effect). However the current mitigation strategy minimizing bubble formation is based primarily on He trapping by nano-size oxide particles. An alternate approach to nanoscale grain size stabilization has been proposed. This is based on the addition of small amounts of atoms that are large compared to the base alloy. At higher temperatures these will diffuse to the grain boundaries and will produce an equilibrium state for the grain size at higher temperatures (thermodynamic stabilization – an equilibrium effect). This would be preferred compared to a kinetic effect, which is not

  11. Framework for understanding LENR processes, using conventional condensed matter physics

    International Nuclear Information System (INIS)

    Chubb, Scott R.

    2006-01-01

    Conventional condensed matter physics provides a unifying framework for understanding low-energy nuclear reactions (LENRs) in solids. In the paper, standard many-body physics techniques are used to illustrate this fact. Specifically, the paper shows that formally the theories by Schwinger, Hagelstein, and Chubb and Chubb (C and C), all can be related to a common set of equations, associated with reaction rate and energy transfer, through a standard many-body physics procedure (R-matrix theory). In each case, particular forms of coherence are used that, implicitly provide a mechanism for understanding how LENRs can proceed without. the emission of high-energy particles. In addition, additional ideas, associated with Conventional Condensed Matter physics, are used to extend the earlier ion band state (IBS) model by C and C. The general model clarifies the origin of coherent. processes that initiate LENRs, through the onset of ion conduction that can occur through ionic fluctuations in nano-scale crystals. In the case of PdD x , these fluctuations begin to occur as x → 1 in sub-lattice structures with characteristic dimensions of 60 nm. The resulting LENRs are triggered by the polarization between injected d's and electrons (immediately above the Fermi energy) that takes place in finite-size PdD crystals. During the prolonged charging of PdD x the applied, external electric field induces these fluctuations through a form of Zener tunneling that mimics the kind of tunneling, predicted by Zener, that is responsible for possible conduction (referred to as Zener-electric breakdown) in insulators. But because the fluctuations are ionic and they occur in PdD, nano-scale structures, a more appropriate characterization is Zener-ionic breakdown in nano-crystalline PdD. Using the underlying dynamics, it is possible to relate triggering times that are required for the initiation of the effect, to crystal size and externally applied fields. (authors)

  12. Nuclear stopping in transmission experiments

    International Nuclear Information System (INIS)

    Glazov, Lev G.; Sigmund, Peter

    2003-01-01

    Energy-loss spectra, mean and peak energy loss, and straggling due to elastic nuclear scattering have been studied theoretically as a function of target thickness and deflection angle of an initially monochromatic and well-collimated ion beam. The goal of this work has been to provide a generally valid scheme for nuclear-stopping corrections, allowing to determine electronic-stopping forces from energy-loss spectra measured in transmission geometry. Calculations have been based on the generalized Bothe-Landau theory of energy loss and multiple scattering. Our peak energy losses at zero emergence angle show close (∼10%) agreement with predictions of Fastrup et al. on the basis of the Bohr-Williams theory. However, predicted mean and peak energy losses are found to more sensitively depend on the underlying interatomic potential than unrestricted, i.e. angle-integrated mean or peak energy losses. Both elastic energy loss and multiple scattering are known to obey scaling laws involving only two combinations of the pertinent variables and atomic parameters. The dependence on deflection angle and foil thickness of mean and peak energy loss obeys a simple combination of these scaling laws. Comments are made on potential errors due to uncertainties in the nuclear-stopping correction applied in the literature with specific reference to central papers in low-velocity stopping

  13. Study of Landau spectrum for a two-dimensional random magnetic field; Etude du spectre de Landau pour un champ magnetique aleatoire en dimension deux

    Energy Technology Data Exchange (ETDEWEB)

    Furtlehner, C. [Paris-6 Univ., 75 (France)

    1997-09-24

    This thesis deals with the two-dimensional problem of a charged particle coupled to a random magnetic field. Various situations are considered, according to the relative importance of the mean value of field and random component. The last one is conceived as a distribution of magnetic impurities (punctual vortex), having various statistical properties (local or non-local correlations, Poisson distribution, etc). The study of this system has led to two distinct situations: - the case of the charged particle feeling the influence of mean field that manifests its presence in the spectrum of broadened Landau levels; - the disordered situation in which the spectrum can be distinguished from the free one only by a low energy Lifshits behaviour. Additional properties are occurring in the limit of `strong` mean field, namely a non-conventional low energy behaviour (in contrast to Lifshits behaviour) which was interpreted in terms of localized states. (author) 78 refs.

  14. Adolescents' knowledge of nuclear issues and the effects of nuclear war

    International Nuclear Information System (INIS)

    Roscoe, B.; Goodwin, M.P.

    1987-01-01

    Three hundred fifty-seven college students were surveyed to assess later adolescents' awareness of the status of nuclear arms development and possible effects of a nuclear war on people and the environment. Chi-square analyses were performed to determine whether the frequency of correct responses differed with regard to participants' sex, political orientation, and position toward the United States' possession of nuclear weapons. Results suggest that later adolescents are extremely uninformed regarding the current status of nuclear issues and the consequences of a nuclear war. These data, coupled with findings from previous studies reporting children's and adolescents' concerns and fears about nuclear war, indicate that there is a strong need to educate young people concerning nuclear issues

  15. Radiation Effects in Nuclear Waste Materials

    International Nuclear Information System (INIS)

    Weber, William J.; Wang, Lumin; Hess, Nancy J.; Icenhower, Jonathan P.; Thevuthasan, Suntharampillai

    2003-01-01

    The objective of this project is to develop a fundamental understanding of radiation effects in glasses and ceramics, as well as the influence of solid-state radiation effects on aqueous dissolution kinetics, which may impact the performance of nuclear waste forms and stabilized nuclear materials. This work provides the underpinning science to develop improved glass and ceramic waste forms for the immobilization and disposition of high-level tank waste, excess plutonium, plutonium residues and scrap, other actinides, and other nuclear waste streams. Furthermore, this work is developing develop predictive models for the performance of nuclear waste forms and stabilized nuclear materials. Thus, the research performed under this project has significant implications for the immobilization of High-Level Waste (HLW) and Nuclear Materials, two mission areas within the Office of Environmental Management (EM). With regard to the HLW mission, this research will lead to improved understanding of radiation-induced degradation mechanisms and their effects on dissolution kinetics, as well as development of predictive models for waste form performance. In the Nuclear Materials mission, this research will lead to improvements in the understanding of radiation effects on the chemical and structural properties of materials for the stabilization and long-term storage of plutonium, highly-enriched uranium, and other actinides. The research uses plutonium incorporation, ion-beam irradiation, and electron-beam irradiation to simulate the effects of alpha decay and beta decay on relevant glasses and ceramics. The research under this project has the potential to result in improved glass and ceramic materials for the stabilization and immobilization of high-level tank waste, plutonium residues and scraps, surplus weapons plutonium, highly-enriched uranium, other actinides, and other radioactive materials

  16. Radiation Effects in Nuclear Waste Materials

    International Nuclear Information System (INIS)

    Weber, William J.

    2005-01-01

    The objective of this project is to develop a fundamental understanding of radiation effects in glasses and ceramics, as well as the influence of solid-state radiation effects on aqueous dissolution kinetics, which may impact the performance of nuclear waste forms and stabilized nuclear materials. This work provides the underpinning science to develop improved glass and ceramic waste forms for the immobilization and disposition of high-level tank waste, excess plutonium, plutonium residues and scrap, other actinides, and other nuclear waste streams. Furthermore, this work is developing develop predictive models for the performance of nuclear waste forms and stabilized nuclear materials. Thus, the research performed under this project has significant implications for the immobilization of High-Level Waste (HLW) and Nuclear Materials, two mission areas within the Office of Environmental Management (EM). With regard to the HLW mission, this research will lead to improved understanding of radiation-induced degradation mechanisms and their effects on dissolution kinetics, as well as development of predictive models for waste form performance. In the Nuclear Materials mission, this research will lead to improvements in the understanding of radiation effects on the chemical and structural properties of materials for the stabilization and long-term storage of plutonium, highly-enriched uranium, and other actinides. The research uses plutonium incorporation, ion-beam irradiation, and electron-beam irradiation to simulate the effects of alpha decay and beta decay on relevant glasses and ceramics. The research under this project has the potential to result in improved glass and ceramic materials for the stabilization and immobilization of high-level tank waste, plutonium residues and scraps, surplus weapons plutonium, highly-enriched uranium, other actinides, and other radioactive materials

  17. Unconventional fractional quantum Hall effect in monolayer and bilayer graphene

    Science.gov (United States)

    Jacak, Janusz; Jacak, Lucjan

    2016-01-01

    The commensurability condition is applied to determine the hierarchy of fractional fillings of Landau levels in monolayer and in bilayer graphene. The filling rates for fractional quantum Hall effect (FQHE) in graphene are found in the first three Landau levels in one-to-one agreement with the experimental data. The presence of even denominator filling fractions in the hierarchy for FQHE in bilayer graphene is explained. Experimentally observed hierarchy of FQHE in the first and second Landau levels in monolayer graphene and in the zeroth Landau level in bilayer graphene is beyond the conventional composite fermion interpretation but fits to the presented nonlocal topology commensurability condition. PMID:27877866

  18. AC relaxation in the iron(8) molecular magnet

    Science.gov (United States)

    Rose, Geordie

    2000-11-01

    We investigate the low energy magnetic relaxation characteristics of the ``iron eight'' (Fe8) molecular magnet. Each molecule in this material contains a cluster of eight Fe 3+ ions surrounded by organic ligands. The molecules arrange themselves into a regular lattice with triclinic symmetry. At sufficiently low energies, the electronic spins of the Fe3+ ions lock together into a ``quantum rotator'' with spin S = 10. We derive a low energy effective Hamiltonian for this system, valid for temperatures less than Tc ~ 360 mK , where Tc is the temperature at which the Fe8 system crosses over into a ``quantum regime'' where relaxation characteristics become temperature independent. We show that in this regime the dominant environmental coupling is to the environmental spin bath in the molecule. We show how to explicitly calculate these couplings, given crystallographic information about the molecule, and do this for Fe8. We use this information to calculate the linewidth, topological decoherence and orthogonality blocking parameters. All of these quantities are shown to exhibit an isotope effect. We demonstrate that orthogonality blocking in Fe8 is significant and suppresses coherent tunneling. We then use our low energy effective Hamiltonian to calculate the single-molecule relaxation rate in the presence of an external magnetic field with both AC and DC components by solving the Landau-Zener problem in the presence of a nuclear spin bath. Both sawtooth and sinusoidal AC fields are analyzed. This single-molecule relaxation rate is then used as input into a master equation in order to take into account the many-molecule nature of the full system. Our results are then compared to quantum regime relaxation experiments performed on the Fe8 system.

  19. Systematic study of the giant monopolar resonance via inelastic scattering of 108.5 MeV 3He. Measurement of the nuclear compressibility

    International Nuclear Information System (INIS)

    Lebrun, Didier.

    1981-09-01

    The giant monopole resonance has been studied via inelastic scattering of 108.5 MeV 3 He at very small angles (including 0 0 ) on approximately 50 nuclei. Its angular distribution reaches its maximum in this region and leads to clear separation with GQR. DWBA analysis shows a smooth increase of the strength from few per cent of the sum rule in light nuclei up to 100% in heavier ones. The excitation energy analysis shows a crossing effect of the monopole and quadrupole frequencies in A = 40-50 region, a coupling effect between the two modes in deformed nuclei, an asymmetry effect in several series of isotopes. Compressibility moduli of nuclear matter Ksub(infinity), surface Ksub(s) and asymmetry Ksub(tau) have seen extracted, as well as the Landau parameter F 0 at saturation [fr

  20. The "Forgotten" Pseudomomenta and Gauge Changes in Generalized Landau Level Problems: Spatially Nonuniform Magnetic and Temporally Varying Electric Fields

    Science.gov (United States)

    Konstantinou, Georgios; Moulopoulos, Konstantinos

    2017-05-01

    By perceiving gauge invariance as an analytical tool in order to get insight into the states of the "generalized Landau problem" (a charged quantum particle moving inside a magnetic, and possibly electric field), and motivated by an early article that correctly warns against a naive use of gauge transformation procedures in the usual Landau problem (i.e. with the magnetic field being static and uniform), we first show how to bypass the complications pointed out in that article by solving the problem in full generality through gauge transformation techniques in a more appropriate manner. Our solution provides in simple and closed analytical forms all Landau Level-wavefunctions without the need to specify a particular vector potential. This we do by proper handling of the so-called pseudomomentum ěc {{K}} (or of a quantity that we term pseudo-angular momentum L z ), a method that is crucially different from the old warning argument, but also from standard treatments in textbooks and in research literature (where the usual Landau-wavefunctions are employed - labeled with canonical momenta quantum numbers). Most importantly, we go further by showing that a similar procedure can be followed in the more difficult case of spatially-nonuniform magnetic fields: in such case we define ěc {{K}} and L z as plausible generalizations of the previous ordinary case, namely as appropriate line integrals of the inhomogeneous magnetic field - our method providing closed analytical expressions for all stationary state wavefunctions in an easy manner and in a broad set of geometries and gauges. It can thus be viewed as complementary to the few existing works on inhomogeneous magnetic fields, that have so far mostly focused on determining the energy eigenvalues rather than the corresponding eigenkets (on which they have claimed that, even in the simplest cases, it is not possible to obtain in closed form the associated wavefunctions). The analytical forms derived here for these