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Sample records for landau der wintershall

  1. Landau damping

    SciTech Connect

    Ng, K.Y.; /Fermilab

    2010-10-01

    Section 2.5.8 of the Handbook of Accelerator Physics and Engineering on Landau damping is rewritten. An solvable example is first given to demonstrate the interplay between Landau damping and decoherence. This example is an actual one when the beam oscillatory motion is driven by a wake force. The dispersion relation is derived and its implication on Landau damping is illustrated. The rest of the article touches on the Landau damping of transverse and longitudinal beam oscillations. The stability criteria are given for a bunched beam and the changes of the criteria when the beam is lengthened and becomes unbunched.

  2. Decoherence and Landau-Damping

    SciTech Connect

    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.

  3. New squeezed landau states

    NASA Technical Reports Server (NTRS)

    Aragone, C.

    1993-01-01

    We introduce a new set of squeezed states through the coupled two-mode squeezed operator. It is shown that their behavior is simpler than the correlated coherent states introduced by Dodonov, Kurmyshev, and Man'ko in order to quantum mechanically describe the Landau system, i.e., a planar charged particle in a uniform magnetic field. We compare results for both sets of squeezed states.

  4. Universal Landau pole.

    PubMed

    Andrianov, A A; Espriu, D; Kurkov, M A; Lizzi, F

    2013-07-01

    Our understanding of quantum gravity suggests that at the Planck scale the usual geometry loses its meaning. If so, the quest for grand unification in a large non-Abelian group naturally endowed with the property of asymptotic freedom may also lose its motivation. Instead, we propose a unification of all fundamental interactions at the Planck scale in the form of a universal Landau pole, at which all gauge couplings diverge. The Higgs quartic coupling also diverges while the Yukawa couplings vanish. The unification is achieved with the addition of fermions with vector gauge couplings coming in multiplets and with hypercharges identical to those of the standard model. The presence of these particles also prevents the Higgs quartic coupling from becoming negative, thus avoiding the instability (or metastability) of the standard model vacuum. PMID:23862991

  5. Landau's Nobel Prize in Physics

    NASA Astrophysics Data System (ADS)

    Larsson, M.; Balatsky, A. V.

    2016-06-01

    Work of Lev Landau had a profound impact on the physics in 20th century. Landau had created the paradigms that had framed the conversations on the outstanding problems in physics for decades. He had laid foundations for our understanding of quantum matter like superfluidity, superconductivity and the theory of Fermi liquid. Here we present some Nobel Archive data on the winning nomination that led to the Nobel Prize in Physics in 1962.

  6. Linear collisionless Landau damping in Hilbert space

    NASA Astrophysics Data System (ADS)

    Zocco, Alessandro

    2015-08-01

    The equivalence between the Laplace transform (Landau, J. Phys. USSR 10 (1946), 25) and Hermite transform (Zocco and Schekochihin, Phys. Plasmas 18, 102309 (2011)) solutions of the linear collisionless Landau damping problem is proven.

  7. Landau damping of auroral hiss

    NASA Technical Reports Server (NTRS)

    Morgan, D. D.; Gurnett, D. A.; Menietti, J. D.; Winningham, J. D.; Burch, J. L.

    1994-01-01

    Auroral hiss is observed to propagate over distances comparable to an Earth radius from its source in the auroral oval. The role of Landau damping is investigated for upward propagating auroral hiss. By using a ray tracing code and a simplified model of the distribution function, the effect of Landau damping is calculated for auroral hiss propagation through the environment around the auroral oval. Landau damping is found to be the likely mechanism for explaining some of the one-sided auroral hiss funnels observed by Dynamics Explorer 1. It is also found that Landau damping puts a lower limit on the wavelength of auroral hiss. Poleward of the auroral oval, Landau damping is found in a typical case to limit omega/k(sub parallel) to values of 3.4 x 10(exp 4) km/s or greater, corresponding to resonance energies of 3.2 keV or greater and wavelengths of 2 km or greater. For equatorward propagation, omega/k(sub parallel) is limited to values greater than 6.8 x 10(exp 4) km/s, corresponding to resonance energies greater than 13 keV and wavelengths greater than 3 km. Independent estimates based on measured ratios of the magnetic to electric field intensity also show that omega/k(sub parallel) corresponds to resonance energies greater than 1 keV and wavelengths greater than 1 km. These results lead to the difficulty that upgoing electron beams sufficiently energetic to directly generate auroral hiss of the inferred wavelength are not usually observed. A partial transmission mechanism utilizing density discontinuities oblique to the magnetic field is proposed for converting auroral hiss to wavelengths long enough to avoid damping of the wave over long distances. Numerous reflections of the wave in an upwardly flared density cavity could convert waves to significantly increased wavelengths and resonance velocities.

  8. Landau damping of auroral hiss

    SciTech Connect

    Morgan, D.D.; Gurnett, D.A.; Menietti, J.D.; Winningham, J.D.; Burch, J.L.

    1994-02-01

    Auroral hiss is observed to propagate over distances comparable to an Earth radius from its source in the auroral oval. The role of Landau damping is investigated for upward propagating auroral hiss. By using a ray tracing code and a simplified model of the distribution function, the effect of Landau damping is calculated for auroral hiss propagation through the environment around the auroral oval. Landau damping is found to be the likely mechanism for explaining some of the one-sided auroral hiss funnels observed by Dynamics Explorer 1. It is also found that Landau damping puts a lower limit on the wavelength of auroral hiss. Poleward of the auroral oval, Landau damping is found in a typical case to limit {omega}/k{parallel} to values of 3.4 x 10{sup 4} km/s or greater, corresponding to resonance energies of 3.2 keV or greater and wavelengths of 2 km or greater. For equatorward propagation, {omega}/k{parallel} is limited to values greater than 6.8 x 10{sup 4} km/s, corresponding to resonance energies greater than 13 keV and wavelengths greater than 3 km. Independent estimates based on measured ratios of the magnetic to electric field intensity also show that {omega}/k{parallel} corresponds to resonance energies greater than 1 keV and wavelengths greater than 1 km. These results lead to the difficulty that upgoing electron beams sufficiently energetic to directly generate auroral hiss of the inferred wavelength are not usually observed. A partial transmission mechanism utilizing density discontinuities oblique to the magnetic field is proposed for converting auroral hiss to wavelengths long enough to avoid damping of the wave over long distances. Numerous reflections of the wave in an upwardly flared density cavity could convert waves to significantly increased wavelengths and resonance velocities. 36 refs., 12 figs., 4 tabs.

  9. Hydrodynamics from Landau initial conditions

    SciTech Connect

    Sen, Abhisek; Gerhard, Jochen; Torrieri, Giorgio; Read jr, Kenneth F.; Wong, Cheuk-Yin

    2015-01-01

    We investigate ideal hydrodynamic evolution, with Landau initial conditions, both in a semi-analytical 1+1D approach and in a numerical code incorporating event-by-event variation with many events and transverse density inhomogeneities. The object of the calculation is to test how fast would a Landau initial condition transition to a commonly used boost-invariant expansion. We show that the transition to boost-invariant flow occurs too late for realistic setups, with corrections of O (20 - 30%) expected at freezeout for most scenarios. Moreover, the deviation from boost-invariance is correlated with both transverse flow and elliptic flow, with the more highly transversely flowing regions also showing the most violation of boost invariance. Therefore, if longitudinal flow is not fully developed at the early stages of heavy ion collisions, 2+1 dimensional hydrodynamics is inadequate to extract transport coefficients of the quark-gluon plasma. Based on [1, 2

  10. Geometric Landau-Zener interferometry.

    PubMed

    Gasparinetti, S; Solinas, P; Pekola, J P

    2011-11-11

    We propose a new type of interferometry, based on geometric phases accumulated by a periodically driven two-level system undergoing multiple Landau-Zener transitions. As a specific example, we study its implementation in a superconducting charge pump. We find that interference patterns appear as a function of the pumping frequency and the phase bias, and clearly manifest themselves in the pumped charge. We also show that the effects described should persist in the presence of realistic decoherence. PMID:22181761

  11. Wang-Landau Without Binning

    NASA Astrophysics Data System (ADS)

    Brown, G.; Nicholson, D.; Odbadrakh, Kh.; Eisenbach, M.; Rusanu, A.

    2012-02-01

    Results are presented for Wang-Landau calculations on a Heisenberg model of BCC Fe that describe the density of states as function defined for all accessible energies instead of a function tabulated at discrete values of the energy. The density of states function described here is an analytic result valid near the ground state supplemented by a polynomial expansion. The probability density of Wang-Landau random walkers is sampled for a fixed density of states, and that probability density can be used to improve the estimated density of states. Methods for evaluating the convergence of the density of states are discussed along with the diffusion behavior of the random walkers. This work was performed at the Oak Ridge National Laboratory, which is managed by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725, and sponsored by the Laboratory Directed Research and Development Program (ORNL), by the Mathematical, Information, and Computational Sciences Division; Office of Advanced Scientific Computing Research (US DOE), and by the Division of Materials Sciences and Engineering; Office of Basic Energy Sciences (US DOE). Computer resources provided by Florida State University.

  12. Photonic Landau levels on cones

    NASA Astrophysics Data System (ADS)

    Schine, Nathan; Ryou, Albert; Gromov, Andrey; Sommer, Ariel; Simon, Jonathan

    2016-05-01

    We present the first experimental realization of a bulk magnetic field for optical photons. By using a non-planar ring resonator, we induce an image rotation on each round trip through the resonator. This results in a Coriolis/Lorentz force and a centrifugal anticonfining force, the latter of which is cancelled by mirror curvature. Using a digital micromirror device to control both amplitude and phase, we inject arbitrary optical modes into our resonator. Spatial- and energy- resolved spectroscopy tracks photonic eigenstates as residual trapping is reduced, and we observe photonic Landau levels as the eigenstates become degenerate. We show that there is a conical geometry of the resulting manifold for photon dynamics and present a measurement of the local density of states that is consistent with Landau levels on a cone. While our work already demonstrates an integer quantum Hall material composed of photons, we have ensured compatibility with strong photon-photon interactions, which will allow quantum optical studies of entanglement and correlation in manybody systems including fractional quantum Hall fluids.

  13. A Landau-Squire nanojet

    PubMed Central

    Laohakunakorn, Nadanai; Gollnick, Benjamin; Moreno-Herrero, Fernando; Aarts, Dirk G. A. L.; Dullens, Roel P. A.; Ghosal, Sandip

    2013-01-01

    Fluid jets are found in nature at all length scales – microscopic to cosmological. Here we report on an electroosmotically driven jet from a single glass nanopore about 75 nm in radius with a maximum flow rate ~ 30 pL/s. A novel anemometry technique allows us to map out the vorticity and velocity fields which show excellent agreement with the classical Landau-Squire solution of the Navier Stokes equations for a point jet. We observe a phenomenon that we call flow rectification: an asymmetry in the flow rate with respect to voltage reversal. Such a nanojet could potentially find applications in micro manipulation, nano patterning, and as a diode in microfluidic circuits. PMID:24124664

  14. Interaction-induced Landau-Zener transitions

    NASA Astrophysics Data System (ADS)

    Larson, Jonas

    2014-08-01

    By considering a quantum-critical Lipkin-Meshkov-Glick model we analyze a new type of Landau-Zener transitions where the population transfer is mediated by interaction rather than from a direct diabatic coupling. For this scenario, at a mean-field level the dynamics is greatly influenced by quantum interferences. In particular, regardless of how slow the Landau-Zener sweep is, for certain parameters almost no population transfer occurs, which is in stark contrast to the regular Landau-Zener model. For moderate system sizes, this counterintuitive mean-field behaviour is not duplicated in the quantum case. This can be attributed to quantum fluctuations and to the fact that multi-level Landau-Zener-Stückelberg interferences have a “dephasing” effect on the above-mentioned phenomenon. We also find a discrepancy between the quantum and mean-field models in terms of how the transfer probabilities scale with the sweep velocity.

  15. Simplified Model of Nonlinear Landau Damping

    SciTech Connect

    N. A. Yampolsky and N. J. Fisch

    2009-07-16

    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. Synthetic Landau levels for photons

    NASA Astrophysics Data System (ADS)

    Schine, Nathan; Ryou, Albert; Gromov, Andrey; Sommer, Ariel; Simon, Jonathan

    2016-06-01

    Synthetic photonic materials are an emerging platform for exploring the interface between microscopic quantum dynamics and macroscopic material properties. Photons experiencing a Lorentz force develop handedness, providing opportunities to study quantum Hall physics and topological quantum science. Here we present an experimental realization of a magnetic field for continuum photons. We trap optical photons in a multimode ring resonator to make a two-dimensional gas of massive bosons, and then employ a non-planar geometry to induce an image rotation on each round-trip. This results in photonic Coriolis/Lorentz and centrifugal forces and so realizes the Fock–Darwin Hamiltonian for photons in a magnetic field and harmonic trap. Using spatial- and energy-resolved spectroscopy, we track the resulting photonic eigenstates as radial trapping is reduced, finally observing a photonic Landau level at degeneracy. To circumvent the challenge of trap instability at the centrifugal limit, we constrain the photons to move on a cone. Spectroscopic probes demonstrate flat space (zero curvature) away from the cone tip. At the cone tip, we observe that spatial curvature increases the local density of states, and we measure fractional state number excess consistent with the Wen–Zee theory, providing an experimental test of this theory of electrons in both a magnetic field and curved space. This work opens the door to exploration of the interplay of geometry and topology, and in conjunction with Rydberg electromagnetically induced transparency, enables studies of photonic fractional quantum Hall fluids and direct detection of anyons.

  17. Synthetic Landau levels for photons.

    PubMed

    Schine, Nathan; Ryou, Albert; Gromov, Andrey; Sommer, Ariel; Simon, Jonathan

    2016-06-30

    Synthetic photonic materials are an emerging platform for exploring the interface between microscopic quantum dynamics and macroscopic material properties. Photons experiencing a Lorentz force develop handedness, providing opportunities to study quantum Hall physics and topological quantum science. Here we present an experimental realization of a magnetic field for continuum photons. We trap optical photons in a multimode ring resonator to make a two-dimensional gas of massive bosons, and then employ a non-planar geometry to induce an image rotation on each round-trip. This results in photonic Coriolis/Lorentz and centrifugal forces and so realizes the Fock–Darwin Hamiltonian for photons in a magnetic field and harmonic trap. Using spatial- and energy-resolved spectroscopy, we track the resulting photonic eigenstates as radial trapping is reduced, finally observing a photonic Landau level at degeneracy. To circumvent the challenge of trap instability at the centrifugal limit, we constrain the photons to move on a cone. Spectroscopic probes demonstrate flat space (zero curvature) away from the cone tip. At the cone tip, we observe that spatial curvature increases the local density of states, and we measure fractional state number excess consistent with the Wen–Zee theory, providing an experimental test of this theory of electrons in both a magnetic field and curved space. This work opens the door to exploration of the interplay of geometry and topology, and in conjunction with Rydberg electromagnetically induced transparency, enables studies of photonic fractional quantum Hall fluids and direct detection of anyons. PMID:27281214

  18. Landau damping in relativistic plasmas

    NASA Astrophysics Data System (ADS)

    Young, Brent

    2016-02-01

    We examine the phenomenon of Landau damping in relativistic plasmas via a study of the relativistic Vlasov-Poisson (rVP) system on the torus for initial data sufficiently close to a spatially uniform steady state. We find that if the steady state is regular enough (essentially in a Gevrey class of degree in a specified range) and if the deviation of the initial data from this steady state is small enough in a certain norm, the evolution of the system is such that its spatial density approaches a uniform constant value quasi-exponentially fast (i.e., like exp ( - C |" separators=" t | ν ¯ ) for ν ¯ ∈ ( 0 , 1 ) ). We take as a priori assumptions that solutions launched by such initial data exist for all times (by no means guaranteed with rVP, but a reasonable assumption since we are close to a spatially uniform state) and that the various norms in question are continuous in time (which should be a consequence of an abstract version of the Cauchy-Kovalevskaya theorem). In addition, we must assume a kind of "reverse Poincaré inequality" on the Fourier transform of the solution. In spirit, this assumption amounts to the requirement that there exists 0 < ϰ < 1 so that the mass in the annulus ϰ ≤ |" separators=" v | < 1 for the solution launched by the initial data is uniformly small for all t. Typical velocity bounds for solutions to rVP launched by small initial data (at least on ℝ6) imply this bound. We note that none of our results require spherical symmetry (a crucial assumption for many current results on rVP).

  19. Second Landau level fractional quantum Hall effects in the Corbino geometry

    NASA Astrophysics Data System (ADS)

    Schmidt, B. A.; Bennaceur, K.; Bilodeau, S.; Gervais, G.; Pfeiffer, L. N.; West, K. W.

    2015-09-01

    For certain measurements, the Corbino geometry has a distinct advantage over the Hall and van der Pauw geometries, in that it provides a direct probe of the bulk 2DEG without complications due to edge effects. This may be important in enabling detection of the non-Abelian entropy of the 5/2 fractional quantum Hall state via bulk thermodynamic measurements. We report the successful fabrication and measurement of a Corbino-geometry sample in an ultra-high mobility GaAs heterostructure, with a focus on transport in the second and higher Landau levels. In particular, we report activation energy gaps of fractional quantum Hall states, with all edge effects ruled out, and extrapolate σ0 from the Arrhenius fits. Our results show that activated transport in the second Landau level remains poorly understood. The development of this Corbino device opens the possibility to study the bulk of the 5/2 state using techniques not possible in other geometries.

  20. The Wave-Kinetic Landau Fluid

    NASA Astrophysics Data System (ADS)

    Joseph, Ilon; Dimits, Andris

    2014-10-01

    Efficient representation of kinetic effects such as Landau damping and particle trapping is crucial for the accuracy of reduced fluid models used to describe collisionless plasma turbulence. A new method for representing nonlinear resonance effects has been developed for Landau fluid models. Wave-kinetic basis functions that focus velocity space resolution on wave-particle resonances naturally generate correct linear and nonlinear Landau damping amplitudes. Perhaps surprisingly, closely spaced resonances are accurately treated using ``inverse'' or ``pseudo'' moments in velocity space. The closure for the fluid moment system is equivalent to the choice of a companion matrix that determines the linear response. This freedom can be used to generate multiple families of closures that generate the same Padé approximation to the linear response, but have different nonlinear behavior. Results have been formally generalized to include trapped particle effects and collisions. LLNL-ABS-656910 prepared for US DOE under Contract DE-AC52-07NA27344.

  1. Particle systems and nonlinear Landau damping

    SciTech Connect

    Villani, Cédric

    2014-03-15

    Some works dealing with the long-time behavior of interacting particle systems are reviewed and put into perspective, with focus on the classical Kolmogorov–Arnold–Moser theory and recent results of Landau damping in the nonlinear perturbative regime, obtained in collaboration with Clément Mouhot. Analogies are discussed, as well as new qualitative insights in the theory. Finally, the connection with a more recent work on the inviscid Landau damping near the Couette shear flow, by Bedrossian and Masmoudi, is briefly discussed.

  2. Landau problem in noncommutative quantum mechanics

    NASA Astrophysics Data System (ADS)

    Sayipjamal, Dulat; Li, Kang

    2008-02-01

    The Landau problem in non-commutative quantum mechanics (NCQM) is studied. First by solving the Schrödinger equations on noncommutative (NC) space we obtain the Landau energy levels and the energy correction that is caused by space-space noncommutativity. Then we discuss the noncommutative phase space case, namely, space-space and momentum-momentum non-commutative case, and we get the explicit expression of the Hamiltonian as well as the corresponding eigenfunctions and eigenvalues. Supported by National Natural Science Foundation of China (10465004, 10665001, 10575026) and Abdus Salam ICTP, Trieste, Italy

  3. Erika Landau: A Lifetime of Creativity

    ERIC Educational Resources Information Center

    Vidergor, Hava

    2014-01-01

    This article unfolds the personal creative characteristics of an educator in the field of gifted education, and examines creativity as expressed in childhood and its transformation into adulthood. Dr. Erika Landau is a pioneer of gifted education in Israel, an internationally renowned scholar and educator, and the founder of the Young…

  4. Further generalization of Landau-Zener calculation

    SciTech Connect

    Carroll, C.E.; Hioe, F.T.

    1985-08-01

    A three-level model is used for an atom driven by laser beams of constant amplitude; their detunings are proportional to the time. Simple formulas for the resulting transition probabilities are derived analytically. Special cases of these results are the Landau-Zener result for a two-level model and our earlier result for a symmetrical three-level model.

  5. Landau-Zener problem for trilinear systems

    SciTech Connect

    Ishkhanyan, Artur; Mackie, Matt; Carmichael, Andrew; Gould, Phillip L.; Javanainen, Juha

    2004-04-01

    We consider a nonlinear version of the Landau-Zener problem, focusing on photoassociation of a Bose-Einstein condensate as a specific example. Contrary to the exponential rate dependence obtained for the linear problem, when the resonance is crossed slowly the no-transition probability is directly proportional to the rate at which the resonance is crossed.

  6. Wigner-crystallization of Rydberg-Polaritons in the lowest Landau level

    NASA Astrophysics Data System (ADS)

    Grusdt, Fabian; Fleischhauer, Michael

    2012-02-01

    For electrons and dipolar fermions in the lowest Landau level the critical filling for Wigner-crystallization was shown to be νc 1/7 [Baranov et. al., Phys. Rev. Lett. 100 (2008)]. We investigate the fractional quantum Hall effect for Van-der-Waals interacting bosons as realized e.g. by stationary-light polaritons in a Rydberg gas and find no transition to the Wigner crystal (WC). Our numerical studies suggest a crystalline groundstate below ν=1/6 which is expected to be described by a correlated WC of composite quasiparticles. Taking into account a cut-off in the Van-der-Waals interaction we find the WC to be favorable for large cut-offs. Numerical results for different geometries are presented and realistic implementations are discussed.

  7. Hydrodynamics on the lowest Landau level

    NASA Astrophysics Data System (ADS)

    Geracie, Michael; Son, Dam Thanh

    2015-06-01

    Using the recently developed approach to quantum Hall physics based on Newton-Cartan geometry, we consider the hydrodynamics of an interacting system on the lowest Landau level. We rephrase the non-relativistic fluid equations of motion in a manner that manifests the spacetime diffeomorphism invariance of the underlying theory. In the massless (or lowest Landau level) limit, the fluid obeys a force-free constraint which fixes the charge current. An entropy current analysis further constrains the energy response, determining four transverse response functions in terms of only two: an energy magnetization and a thermal Hall conductivity. Kubo formulas are presented for all transport coefficients and constraints from Weyl invariance derived. We also present a number of Středa-type formulas for the equilibrium response to external electric, magnetic and gravitational fields.

  8. Landau Levels in Strained Optical Lattices

    NASA Astrophysics Data System (ADS)

    Tian, Binbin; Endres, Manuel; Pekker, David

    2015-12-01

    We propose a hexagonal optical lattice system with spatial variations in the hopping matrix elements. Just like in the valley Hall effect in strained graphene, for atoms near the Dirac points the variations in the hopping matrix elements can be described by a pseudomagnetic field and result in the formation of Landau levels. We show that the pseudomagnetic field leads to measurable experimental signatures in momentum resolved Bragg spectroscopy, Bloch oscillations, cyclotron motion, and quantization of in situ densities. Our proposal can be realized by a slight modification of existing experiments. In contrast to previous methods, pseudomagnetic fields are realized in a completely static system avoiding common heating effects and therefore opening the door to studying interaction effects in Landau levels with cold atoms.

  9. Landau-like states in neutral particles

    NASA Astrophysics Data System (ADS)

    Banerjee, Saikat; Ågren, Hans; Balatsky, A. V.

    2016-06-01

    We show the emergence of a new type of dispersion relation for neutral atoms with an interesting similarity to the spectrum of two-dimensional electrons in an applied perpendicular constant magnetic field. These neutral atoms can be confined in toroidal optical traps and give quasi-Landau spectra. In strong contrast to the equidistant infinitely degenerate Landau levels for charged particles, the spectral gap for such two-dimensional neutral particles increases in particular electric-field configurations. The idea in the paper is motivated by the development in cold atom experiments and builds on the seminal paper of Aharonov and Casher [Phys. Rev. Lett. 53, 319 (1984), 10.1103/PhysRevLett.53.319].

  10. Nonlinear Landau damping in the ionosphere

    NASA Technical Reports Server (NTRS)

    Kiwamoto, Y.; Benson, R. F.

    1978-01-01

    A model is presented to explain the non-resonant waves which give rise to the diffuse resonance observed near 3/2 f sub H by the Alouette and ISIS topside sounders, where f sub H is the ambient electron cyclotron frequency. In a strictly linear analysis, these instability driven waves will decay due to Landau damping on a time scale much shorter than the observed time duration of the diffuse resonance. Calculations of the nonlinear wave particle coupling coefficients, however, indicate that the diffuse resonance wave can be maintained by the nonlinear Landau damping of the sounder stimulated 2f sub H wave. The time duration of the diffuse resonance is determined by the transit time of the instability generated and nonlinearly maintained diffuse resonance wave from the remote short lived hot region back to the antenna. The model is consistent with the Alouette/ISIS observations, and clearly demonstrates the existence of nonlinear wave-particle interactions in the ionosphere.

  11. Landau damping in a turbulent setting

    SciTech Connect

    Plunk, G. G.

    2013-03-15

    To address the problem of Landau damping in kinetic turbulence, we consider the forcing of the linearized Vlasov equation by a stationary random source. It is found that the time-asymptotic density response is dominated by resonant particle interactions that are synchronized with the source. The energy consumption of this response is calculated, implying an effective damping rate, which is the main result of this paper. Evaluating several cases, it is found that the effective damping rate can differ from the Landau damping rate in magnitude and also, remarkably, in sign. A limit is demonstrated in which the density and current become phase-locked, which causes the effective damping to be negligible; this result offers a fresh perspective from which to reconsider recent observations of kinetic turbulence satisfying critical balance.

  12. Mesoscopic Superposition States in Relativistic Landau Levels

    SciTech Connect

    Bermudez, A.; Martin-Delgado, M. A.; Solano, E.

    2007-09-21

    We show that a linear superposition of mesoscopic states in relativistic Landau levels can be built when an external magnetic field couples to a relativistic spin 1/2 charged particle. Under suitable initial conditions, the associated Dirac equation produces unitarily superpositions of coherent states involving the particle orbital quanta in a well-defined mesoscopic regime. We demonstrate that these mesoscopic superpositions have a purely relativistic origin and disappear in the nonrelativistic limit.

  13. Landau Fluid Models for Magnetized Plasmas

    SciTech Connect

    Sulem, P. L.; Passot, T.; Marradi, L.

    2008-10-15

    A Landau fluid model for a magnetized plasma, that retains a linear description of low-frequency kinetic effects involving transverse scales significantly smaller than the ion Larmor radius, is discussed and validated in the context of nonlinear wave dynamics. Preliminary simulations of the turbulent regime are presented in one space dimension, as a first step towards more realistic three-dimensional computations, aimed to analyze the combined effect of dispersion and collisionless dissipation on the energy cascade.

  14. Our Understanding on Landau-Raychaudhuri Cosmology

    NASA Astrophysics Data System (ADS)

    Magied Diab, Abdel; Nasser Tawfik, Abdel

    2016-01-01

    Recent developments to the generalized uncertainty principles (GUPs) and the modified dispersion relations (MDRs) play an important role in estimating the quantum corrections to the cosmic line element. We first apply both approaches to de Sitter-Schwarzschild and Reissner-Nordstrom black holes. Then from the fixed point method, the modified Landau- Raychaudhuri equations are derived in emergent cosmic space. We conclude that (non-)singular big bang solutions are obviously model dependent.

  15. Bounce harmonic Landau damping of plasma waves

    NASA Astrophysics Data System (ADS)

    Anderegg, F.; Affolter, M.; Kabantsev, A. A.; Dubin, D. H. E.; Ashourvan, A.; Driscoll, C. F.

    2016-05-01

    We present measurements of bounce harmonic Landau damping due to z-variations in the plasma potential, created by an azimuthally symmetric "squeeze" voltage Vs applied to the cylindrical wall. Traditional Landau damping on spatially uniform plasma is weak in regimes where the wave phase velocity vp h≡ω/k is large compared to the thermal velocity. However, z-variations in plasma density and potential create higher spatial harmonics, which enable resonant wave damping by particles with bounce-averaged velocities vp h/n , where n is an integer. In our geometry, the applied squeeze predominantly generates a resonance at vp h/3 . Wave-coherent laser induced fluorescence measurements of particle velocities show a distinctive Landau damping signature at vp h/3 , with amplitude proportional to the applied Vs. The measured (small amplitude) wave damping is then proportional to Vs2 , in quantitative agreement with theory over a range of 20 in temperature. Significant questions remain regarding "background" bounce harmonic damping due to ubiquitous confinement fields and regarding the saturation of this damping at large wave amplitudes.

  16. New physics in the second Landau Level

    NASA Astrophysics Data System (ADS)

    Csathy, Gabor

    2006-03-01

    Clean two-dimensional electron systems subjected to perpendicular magnetic fields have a long history of revealing exotic ground states. A large number of these states are only possible in the presence of electron-electron interactions. Two notable examples of such collective ground states are the fractional quantum Hall liquids of the first two Landau levels and the electronic solids called the stripe and bubble phases forming beyond the first Landau level. These two classes of phases are simultaneously present and hence compete in the second Landau level. This talk will highlight our latest results on the evolution of the states of the second Landau level as the magnetic field is tilted away from the direction perpendicular to the sample. The challenging task of cooling to millidegree temperatures and in-situ tilting in this low temperature environment is achieved with a hydraulically driven rotator equipped with sintered Silver heat exchangers mounted onto the nuclear demagnetization stage of a dilution refrigerator. We found that the bubble states are rapidly destroyed with tilt and argue that such a behavior is consistent with the formation of an electronic solid. Furthermore, the well developed ν = 2+1/5 and 2+4/5 liquids are found to be driven insulating while the 2+1/3 and 2+2/3 states survive to the largest tilt angles accessible. The simplest interpretation of the rapid evolution of these states is that bubble phases melt into a classical Hall gas and the ν = 2+1/5 and 2+4/5 liquids solidify with tilt. Our data suggest that spin interaction plays an important role in the formation of these phases. In particular, we surmise that the bubble phases are not fully spin-polarized but most likely have a substantial antiferromagnetic order. These bubble phases could be first examples of antiferromagnetically ordered solids in a single layer two-dimensional electron system. This work was done in collaboration with J.S. Xia, C.L. Vicente, E.D. Adams, N

  17. Landau theory for helical nematic phases

    NASA Astrophysics Data System (ADS)

    Kats, E. I.; Lebedev, V. V.

    2014-09-01

    We propose Landau phenomenology for the phase transition from the conventional nematic into the conical helical orientationally non-uniform structure recently identified in liquid crystals formed by "banana"-shaped molecules. The mean field predictions are mostly in agreement with experimental data. Based on the analogy with de Gennes model, we argue that fluctuations of the order parameter turn the transition to the first order phase transition rather than continuous one predicted by the mean-field theory. This conclusion is in agreement with experimental observations. We discuss the new Goldstone mode to be observed in the low-temperature phase.

  18. SU(3) Landau-Zener interferometry

    NASA Astrophysics Data System (ADS)

    Kiselev, M. N.; Kikoin, K.; Kenmoe, M. B.

    2013-12-01

    We propose a universal approach to the Landau-Zener problem in a three-level system. The problem is formulated in terms of Gell-Mann operators which generate SU(3) algebra and map the Hamiltonian on the effective anisotropic pseudospin 1 model. The vector Bloch equation for the density matrix describing the temporal evolution of the three-level crossing problem is also derived and solved analytically for the case where the diabatic states of the SU(3) Hamiltonian form a triangle. This analytic solution is in excellent quantitative agreement with the numerical solution of the Schrödinger equation for a 3-level crossing problem. The model demonstrates oscillation patterns which radically differ from the standard patterns for the two-level Landau-Zener problem. The triangle works as an interferometer and the interplay between two paths results in formation of “beats” and “steps” pattern in the time-dependent transition probability. The characteristic time scales describing the “beats” and “steps” depend on a dwell time in the triangle. These scales are related to the geometric size of the interferometer. The possibilities of the experimental realization of this effect in triple quantum dots and in two-well traps for cold gases are discussed.

  19. Relativistic Landau models and generation of fuzzy spheres

    NASA Astrophysics Data System (ADS)

    Hasebe, Kazuki

    2016-07-01

    Noncommutative geometry naturally emerges in low energy physics of Landau models as a consequence of level projection. In this work, we proactively utilize the level projection as an effective tool to generate fuzzy geometry. The level projection is specifically applied to the relativistic Landau models. In the first half of the paper, a detail analysis of the relativistic Landau problems on a sphere is presented, where a concise expression of the Dirac-Landau operator eigenstates is obtained based on algebraic methods. We establish SU(2) “gauge” transformation between the relativistic Landau model and the Pauli-Schrödinger nonrelativistic quantum mechanics. After the SU(2) transformation, the Dirac operator and the angular momentum operators are found to satisfy the SO(3, 1) algebra. In the second half, the fuzzy geometries generated from the relativistic Landau levels are elucidated, where unique properties of the relativistic fuzzy geometries are clarified. We consider mass deformation of the relativistic Landau models and demonstrate its geometrical effects to fuzzy geometry. Super fuzzy geometry is also constructed from a supersymmetric quantum mechanics as the square of the Dirac-Landau operator. Finally, we apply the level projection method to real graphene system to generate valley fuzzy spheres.

  20. Landau-Zener approximations for resonant neutrino oscillations

    SciTech Connect

    Whisnant, K.

    1988-07-15

    A simple method for calculating the effects of resonant neutrino oscillations using Landau-Zener approximations is presented. For any given set of oscillation parameters, the method is to use the Landau-Zener approximation which works best in that region.

  1. Landau-Lifshitz theory of thermomagnonic torque

    NASA Astrophysics Data System (ADS)

    Kim, Se Kwon; Tserkovnyak, Yaroslav

    2015-07-01

    We derive the thermomagnonic torque associated with smooth magnetic textures subjected to a temperature gradient in the framework of the stochastic Landau-Lifshitz-Gilbert equation. Our approach captures on equal footing two distinct contributions: (i) a local entropic torque that is caused by a temperature dependence of the effective exchange field, the existence of which had been previously suggested based on numerics, and (ii) the well-known spin-transfer torque induced by thermally induced magnon flow. The dissipative components of two torques have the same structure, following a common phenomenology, but opposite signs, with the twice as large entropic torque leading to a domain-wall motion toward the hotter region. We compare the efficiency of the torque-driven domain-wall motion with the recently proposed Brownian thermophoresis.

  2. Magnetic Flux Quantization of the Landau Problem

    NASA Astrophysics Data System (ADS)

    Wang, Jianhua; Li, Kang; Long, Shuming; Yuan, Yi

    2014-08-01

    Landau problem has a very important application in modern physics, in which two-dimensional electron gas system and quantum Hall effect are outstanding. In this paper, first we review the solution of the Pauli equation, then using the single electron wave function, we calculate moving area expectations of the ideal 2-dimensional electron gas system and the per unit area's degeneracy of the electron gas system. As a result, how to calculate the magnetic flux of the electron gas system is given. It shows that the magnetic flux of 2-dimensional electron gas system in magnetic field is quantized, and magnetic flux quantization results from the quantization of the moving area expectations of electron gas system.

  3. Universal Landau Pole at the Planck scale

    SciTech Connect

    Andrianov, Alexander A.; Espriu, Domenec; Kurkov, Maxim A.; Lizzi, Fedele

    2014-07-23

    The concept of quantum gravity entails that the usual geometry loses its meaning at very small distances and therefore the grand unification of all gauge interactions with the property of asymptotic freedom happens to be questionable. We propose an unification of all gauge interactions in the form of an “Universal Landau Pole” (ULP), at which all gauge couplings diverge (or, better to say, become very strong). We show that the Higgs quartic coupling also substantially increases whereas the Yukawa couplings tend to zero. Such a singular (or strong coupling) unification is obtained after adding to the Standard Model matter more fermions with vector gauge couplings and hypercharges identical to the SM fermions. The influence of new particles also may prevent the Higgs quartic coupling from crossing zero, thus avoiding the instability (or metastability) of the SM vacuum. As well this fermion pattern opens a way to partially solve the hierarchy problem between masses of quarks and leptons.

  4. Coarse-graining Landau-Lifshitz damping

    NASA Astrophysics Data System (ADS)

    Feng, Xuebing; Visscher, P. B.

    2001-06-01

    High speed switching in magnetic materials is usually studied with the Landau-Lifshitz (LL) equation, which describes damping through a phenomenological coefficient. The results of micromagnetic calculations based on the LL equation have been observed to depend strongly on the cell size. We take a coarse-graining or renormalization-group approach to this cell size dependence: from a simulation using cell size L, we look at the dynamics of a cell of size 2L and determine an effective damping coefficient that describes the larger-scale dynamics. This can be thought of as a Green-Kubo calculation of the effective damping coefficient. In principle, this makes it possible to coarse grain from the atomic scale to determine the micromagnetic damping coefficient.

  5. Vortex distribution in the lowest Landau level

    NASA Astrophysics Data System (ADS)

    Aftalion, Amandine; Blanc, Xavier; Nier, Francis

    2006-01-01

    We study the vortex distribution of the wave functions minimizing the Gross-Pitaevskii energy for a fast rotating condensate in the lowest Landau level (LLL): we prove that the minimizer cannot have a finite number of zeroes, thus the lattice is infinite, but not uniform. This uses the explicit expression of the projector onto the LLL. We also show that any slow varying envelope function can be approximated in the LLL by distorting the lattice. This is used in particular to approximate the inverted parabola and understand the role of “invisible” vortices: the distortion of the lattice is very small in the Thomas-Fermi region but quite large outside, where the “invisible” vortices lie.

  6. Universality in dissipative Landau-Zener transitions

    SciTech Connect

    Orth, Peter P.; Le Hur, Karyn; Imambekov, Adilet

    2010-09-15

    We introduce a random-variable approach to investigate the dynamics of a dissipative two-state system. Based on an exact functional integral description, our method reformulates the problem as that of the time evolution of a quantum state vector subject to a Hamiltonian containing random noise fields. This numerically exact, nonperturbative formalism is particularly well suited in the context of time-dependent Hamiltonians, at both zero and finite temperature. As an important example, we consider the renowned Landau-Zener problem in the presence of an Ohmic environment with a large cutoff frequency at finite temperature. We investigate the ''scaling'' limit of the problem at intermediate times, where the decay of the upper-spin-state population is universal. Such a dissipative situation may be implemented using a cold-atom bosonic setup.

  7. Landau-Zener type surface hopping algorithms.

    PubMed

    Belyaev, Andrey K; Lasser, Caroline; Trigila, Giulio

    2014-06-14

    A class of surface hopping algorithms is studied comparing two recent Landau-Zener (LZ) formulas for the probability of nonadiabatic transitions. One of the formulas requires a diabatic representation of the potential matrix while the other one depends only on the adiabatic potential energy surfaces. For each classical trajectory, the nonadiabatic transitions take place only when the surface gap attains a local minimum. Numerical experiments are performed with deterministically branching trajectories and with probabilistic surface hopping. The deterministic and the probabilistic approach confirm the affinity of both the LZ probabilities, as well as the good approximation of the reference solution computed by solving the Schrödinger equation via a grid based pseudo-spectral method. Visualizations of position expectations and superimposed surface hopping trajectories with reference position densities illustrate the effective dynamics of the investigated algorithms. PMID:24929375

  8. Landau-Zener effect in fission

    SciTech Connect

    Mirea, M.; Tassan-Got, L.; Stephan, C.; Bacri, C. O.; Bobulescu, R. C.

    2007-12-15

    A model that takes into account the Landau-Zener promotion mechanism during fission was developed recently. The structures observed in the subthreshold neutron-induced fission of {sup 232}Th are investigated employing this model. Theoretical single-particle excitations of a phenomenological two-humped barrier are determined by solving a system of coupled differential equations for the motion along the optimal fission path. A rather good agreement with experimental data is obtained using a small number of independent parameters. It is predicted that the structure at 1.4 and 1.6 MeV is mainly dominated by a spin 3/2 partial cross section with a small admixture of spin 1/2, while the structure at 1.7 MeV is given by a large partial cross section of spin 5/2.

  9. The Landau-Kleffner syndrome: increased understanding.

    PubMed

    Gordon, N

    1997-07-01

    The Landau-Kleffner and the continuous spike and wave discharges during slow sleep (CSWS) syndromes are described and possible links between the two are discussed. They certainly overlap, with clinical and electroencephalographic features in common. Potential causes are discussed. There is seldom a definite reason for the seizures but it way well be that the spike and wave discharges seen in the EEG, whatever their origin, may disrupt the development of language and cognitive function at a critical stage. If neurons and axons are involved in this disorganized activity they surely cannot perform normally. The evidence that these discharges in the Landau-Kleffner syndrome can have a focal origin in areas important for language supports this hypothesis. Certain variations among studies quoted may be due to factors such as age of onset, the duration of the paroxysmal activity, its intensity and especially its localization. Also, if development has been distorted subsequent progress is likely to be disturbed after the primary condition has ceased to exist. The diagnosis can sometimes present difficulties, for example from deafness, psychiatric condition, post-ical dysphasia and from progressive degenerative neurological disorders. If the possible role of the epileptic activity is accepted, there are strong reasons for advocating anti-epileptic treatment, even if overt seizures are rare. The response to drugs is varied. Fits will usually stop, but not so often the spike and wave discharges, and it is justifiable to try various regimes. Subpial resection has been reported to be successful, possibly by preventing the cortex generating seizures, and their spread. PMID:9253482

  10. Umsetzung der Unternehmensstrategie mit der Balanced Scorecard

    NASA Astrophysics Data System (ADS)

    Crespo, Isabel; Bergmann, Lars; Portmann, Stefan; Lacker, Thomas; Lacker, Michael; Fleischmann, Jürgen; Kozó, Hans

    Die Balanced Scorecard (BSC) ist ein Ansatz zum strategischen Management, der neben der Ausrichtung des Unternehmens auf finanzielle Zielwerte ebenso großes Gewicht auf so genannte weiche Faktoren legt, die den wirtschaftlichen Erfolg eines Unternehmens erst ermöglichen. Das entscheidende Merkmal der Balanced Scorecard ist dabei, dass sie ein ausgewogenes System strategischer Ziele herstellt, welches das Unternehmen hinsichtlich der vier Perspektiven Finanzen, Kunden, interne Prozesse und Mitarbeiter und Potenziale strategisch ausrichtet (Kaplan u. Norton 1997).

  11. Cavity-mediated entanglement generation via Landau-Zener interferometry.

    PubMed

    Quintana, C M; Petersson, K D; McFaul, L W; Srinivasan, S J; Houck, A A; Petta, J R

    2013-04-26

    We demonstrate quantum control and entanglement generation using a Landau-Zener beam splitter formed by coupling two transmon qubits to a superconducting cavity. Single passage through the cavity-mediated qubit-qubit avoided crossing provides a direct test of the Landau-Zener transition formula. Consecutive sweeps result in Landau-Zener-Stückelberg interference patterns, with a visibility that can be sensitively tuned by adjusting the level velocity through both the nonadiabatic and adiabatic regimes. Two-qubit state tomography indicates that a Bell state can be generated via a single passage, with a fidelity of 78% limited by qubit relaxation. PMID:23679727

  12. The minimum-uncertainty coherent states for Landau levels

    SciTech Connect

    Dehghani, A.; Fakhri, H.; Mojaveri, B.

    2012-12-15

    The Glauber minimum-uncertainty coherent states with two variables for Landau levels, based on the representation of Weyl-Heisenberg algebra by two different modes, have been studied about four decades ago. Here, we introduce new two-variable coherent states with minimum uncertainty relationship for Landau levels in three different methods: the infinite unitary representation of su(1, 1) is realized in two different methods, first, by consecutive levels with the same energy gaps and also with the same value for z-angular momentum quantum number, then, by shifting z-angular momentum mode number by two units while the energy level remaining the same. Besides, for su(2), whether by lowest Landau levels or Landau levels with lowest z-angular momentum, just one finite unitary representation is introduced. Having constructed the generalized Klauder-Perelomov coherent states, for any of the three representations, we obtain their Glauber coherency by displacement operator of Weyl-Heisenberg algebra.

  13. Optical Emission from quantum phases of the second Landau level

    NASA Astrophysics Data System (ADS)

    Levy, Antonio; Wurstbauer, Ursula; Pinczuk, Aron; Watson, John; Mondal, Sumit; Manfra, Michael; West, Ken; Pfeiffer, Loren; Purdue Unviersity Collaboration; Princeton University Collaboration; Columbia University Team

    2014-03-01

    Optical emission across the host semiconductor bandgap has proven a powerful tool in examining the properties fractional quantum Hall sates (fqhs). While the luminescence of fqhs in the first (N =0) Landau Level has been extensively studied, there are significantly fewer studies of the optical emission in the N =1 Landau Level. We report studies of luminescence in the filling factor range 4>nu>2 N =1 Landau level. The marked dependence on filling factor suggests that optical emission is here linked to competing quantum phases. A comparison of luminescence in a range about ν = 7/3 with extensively studied optical emission near ν = 1/3 creates venues to explore the competing quantum phases of the second Landau levels.

  14. The minimum-uncertainty coherent states for Landau levels

    NASA Astrophysics Data System (ADS)

    Dehghani, A.; Fakhri, H.; Mojaveri, B.

    2012-12-01

    The Glauber minimum-uncertainty coherent states with two variables for Landau levels, based on the representation of Weyl-Heisenberg algebra by two different modes, have been studied about four decades ago. Here, we introduce new two-variable coherent states with minimum uncertainty relationship for Landau levels in three different methods: the infinite unitary representation of su(1, 1) is realized in two different methods, first, by consecutive levels with the same energy gaps and also with the same value for z-angular momentum quantum number, then, by shifting z-angular momentum mode number by two units while the energy level remaining the same. Besides, for su(2), whether by lowest Landau levels or Landau levels with lowest z-angular momentum, just one finite unitary representation is introduced. Having constructed the generalized Klauder-Perelomov coherent states, for any of the three representations, we obtain their Glauber coherency by displacement operator of Weyl-Heisenberg algebra.

  15. Spectrum Analysis of the Linearized Relativistic Landau Equation

    NASA Astrophysics Data System (ADS)

    Luo, Lan; Yu, Hongjun

    2016-05-01

    In this work we prove the complete spectrum structure of the linearized relativistic Landau equation in L^2 by using the semigroup theory and the linear operator perturbation theory. Our results include the physical interesting Coulombic interaction.

  16. Neutrino oscillations and the Landau-Zener formula

    SciTech Connect

    Kim, C.W.; Sze, W.K.; Nussinov, S.

    1987-06-15

    We discuss solar-neutrino oscillations and the Landau-Zener probability using a heuristic picture in analogy with an electron spin in a time-dependent magnetic field. The extreme nonadiabatic resonant oscillation is also briefly investigated.

  17. Photon and electron Landau damping in quantum plasmas

    NASA Astrophysics Data System (ADS)

    Mendonça, J. T.; Serbeto, A.

    2016-09-01

    Using a quantum kinetic description, we establish a general expression for the dispersion relation of electron plasma waves in the presence of an arbitrary spectrum of electromagnetic waves. This includes both electron and photon Landau damping. The quantum kinetic description allows us to compare directly these two distinct processes, and to show that they are indeed quite similar. The present work also extends previous results on photon Landau damping onto the quantum domain.

  18. Knot solitons in a modified Ginzburg-Landau model

    SciTech Connect

    Jaeykkae, Juha; Palmu, Joonatan

    2011-05-15

    We study a modified version of the Ginzburg-Landau model suggested by Ward and show that Hopfions exist in it as stable static solutions, for values of the Hopf invariant up to at least 7. We also find that their properties closely follow those of their counterparts in the Faddeev-Skyrme model. Finally, we lend support to Babaev's conjecture that longer core lengths yield more stable solitons and propose a possible mechanism for constructing Hopfions in pure Ginzburg-Landau model.

  19. Index formulas and charge deficiencies on the Landau levels

    NASA Astrophysics Data System (ADS)

    Goffeng, Magnus

    2010-02-01

    The notion of charge deficiency by Avron et al. ["Charge deficiency, charge transport and comparison of dimensions," Commun. Math. Phys. 159, 399 (1994)] is studied from the view of K-theory of operator algebras and is applied to the Landau levels in R2n. We calculate the charge deficiencies at the higher Landau levels in R2n by means of an Atiyah-Singer-type index theorem.

  20. Massively parallel Wang Landau sampling on multiple GPUs

    SciTech Connect

    Yin, Junqi; Landau, D. P.

    2012-01-01

    Wang Landau sampling is implemented on the Graphics Processing Unit (GPU) with the Compute Unified Device Architecture (CUDA). Performances on three different GPU cards, including the new generation Fermi architecture card, are compared with that on a Central Processing Unit (CPU). The parameters for massively parallel Wang Landau sampling are tuned in order to achieve fast convergence. For simulations of the water cluster systems, we obtain an average of over 50 times speedup for a given workload.

  1. Landau-Zener treatments of solar neutrino oscillations

    SciTech Connect

    Bruggen, M. Institute for Nuclear Theory, NK-12, University of Washington, Seattle, Washington 98195 ); Haxton, W.C.; Qian, Y. )

    1995-04-15

    We present a simple derivation of the Landau-Zener formulas for nonadiabatic level crossings for linear and exponential density profiles. The derivation depends on a single assumption that applies somewhat differently to the exponential and linear cases, providing some insight into the relationship between the respective formulas. We note that one exponential Landau-Zener formula in common use is only approximately correct. Comparisons with exact calculations are made.

  2. Fault-tolerant Landau-Zener quantum gates

    SciTech Connect

    Hicke, C.; Santos, L. F.; Dykman, M. I.

    2006-01-15

    We present a method to perform fault-tolerant single-qubit gate operations using Landau-Zener tunneling. In a single Landau-Zener pulse, the qubit transition frequency is varied in time so that it passes through the frequency of the radiation field. We show that a simple three-pulse sequence allows eliminating errors in the gate up to the third order in errors in the qubit energies or the radiation frequency.

  3. Landau-Zener treatments of solar neutrino oscillations

    SciTech Connect

    Bruggen, M. |; Haxton, W.C.; Qian, Y.Z.

    1995-01-01

    The authors present a simple derivation of Landau-Zener formulae for nonadiabatic level crossings for linear and exponential density profiles. The derivation depends on a single assumption that applies somewhat differently to the exponential and linear cases, providing some insight into the relationship between the respective formulae. They note that one exponential Landau-Zener formula in common use is only approximately correct. Comparisons with exact calculations are made.

  4. Pairing in half-filled Landau level

    SciTech Connect

    Wang, Zhiqiang; Mandal, Ipsita; Chung, Suk Bum; Chakravarty, Sudip

    2014-12-15

    Pairing of composite fermions in half-filled Landau level state is reexamined by solving the BCS gap equation with full frequency dependent current–current interactions. Our results show that there can be a continuous transition from the Halperin–Lee–Read state to a chiral odd angular momentum Cooper pair state for short-range contact interaction. This is at odds with the previously established conclusion of first order pairing transition, in which the low frequency effective interaction was assumed for the entire frequency range. We find that even if the low frequency effective interaction is repulsive, it is compensated by the high frequency regime, which is attractive. We construct the phase diagrams and show that ℓ=1 angular momentum channel is quite different from higher angular momenta ℓ≥3. Remarkably, the full frequency dependent analysis applied to the bilayer Hall system with a total filling fraction ν=1/2 +1/2 is quantitatively changed from the previously established results but not qualitatively.

  5. Measurement-assisted Landau-Zener transitions

    NASA Astrophysics Data System (ADS)

    Pechen, Alexander; Trushechkin, Anton

    2015-05-01

    Nonselective quantum measurements, i.e., measurements without reading the results, are often considered as a resource for manipulating quantum systems. In this work, we investigate optimal acceleration of the Landau-Zener (LZ) transitions by nonselective quantum measurements. We use the measurements of a population of a diabatic state of the LZ system at certain time instants as control and find the optimal time instants which maximize the LZ transition. We find surprising nonmonotonic behavior of the maximal transition probability with increase of the coupling parameter when the number of measurements is large. This transition probability gives an optimal approximation to the fundamental quantum Zeno effect (which corresponds to continuous measurements) by a fixed number of discrete measurements. The difficulty for the analysis is that the transition probability as a function of time instants has a huge number of local maxima. We resolve this problem both analytically by asymptotic analysis and numerically by the development of efficient algorithms mainly based on the dynamic programming. The proposed numerical methods can be applied, besides this problem, to a wide class of measurement-based optimal control problems.

  6. Loss of Landau Damping for Bunch Oscillations

    SciTech Connect

    Burov, A.; /Fermilab

    2011-04-11

    Conditions for the existence, uniqueness and stability of self-consistent bunch steady states are considered. For the existence and uniqueness problems, simple algebraic criteria are derived for both the action and Hamiltonian domain distributions. For the stability problem, van Kampen theory is used. The onset of a discrete van Kampen mode means the emergence of a coherent mode without any Landau damping; thus, even a tiny couple-bunch or multi-turn wake is sufficient to drive the instability. The method presented here assumes an arbitrary impedance, RF shape, and beam distribution function. Available areas on the intensity-emittance plane are shown for resistive wall wake and single harmonic, bunch shortening and bunch lengthening RF configurations. Thresholds calculated for the Tevatron parameters and impedance model are in agreement with the observations. These thresholds are found to be extremely sensitive to the small-argument behaviour of the bunch distribution function. Accordingly, a method to increase the LLD threshold is suggested. This article summarizes and extends recent author's publications.

  7. Sign language in Landau-Kleffner syndrome.

    PubMed

    Deonna, Thierry; Prelaz-Girod, Anne-Claude; Mayor-Dubois, Claire; Roulet-Perez, Eliane

    2009-08-01

    This article reviews the history of sign language (SL) and the rationale for its use in children with profound auditory agnosia due to Landau-Kleffner syndrome (LKS), illustrated by studies of children and adults followed for many years and rare cases from the literature. The reasons that SL was successful and brought some children out of isolation while it could not be implemented in others are discussed. The nowadays earlier recognition and treatment of LKS and better awareness of the crucial need to maintain communication have certainly improved the outcome of affected children. Alternatives to oral language, even for less severe cases, are increasingly accepted. SL can be learned at different ages with a clear benefit, but the ambivalence of the patients and their families with the world and culture of the deaf may sometimes explain its refusal or limited acceptance. There are no data to support the fear that SL learning may delay or prevent oral language recovery in children with LKS. On the contrary, SL may even facilitate this recovery by stimulating functionally connected core language networks and by helping speech therapy and auditory training. PMID:19682058

  8. Imaging the dynamics of free-electron Landau states

    PubMed Central

    Schattschneider, P.; Schachinger, Th.; Stöger-Pollach, M.; Löffler, S.; Steiger-Thirsfeld, A.; Bliokh, K. Y.; Nori, Franco

    2014-01-01

    Landau levels and states of electrons in a magnetic field are fundamental quantum entities underlying the quantum Hall and related effects in condensed matter physics. However, the real-space properties and observation of Landau wave functions remain elusive. Here we report the real-space observation of Landau states and the internal rotational dynamics of free electrons. States with different quantum numbers are produced using nanometre-sized electron vortex beams, with a radius chosen to match the waist of the Landau states, in a quasi-uniform magnetic field. Scanning the beams along the propagation direction, we reconstruct the rotational dynamics of the Landau wave functions with angular frequency ~100 GHz. We observe that Landau modes with different azimuthal quantum numbers belong to three classes, which are characterized by rotations with zero, Larmor and cyclotron frequencies, respectively. This is in sharp contrast to the uniform cyclotron rotation of classical electrons, and in perfect agreement with recent theoretical predictions. PMID:25105563

  9. Imaging the dynamics of free-electron Landau states.

    PubMed

    Schattschneider, P; Schachinger, Th; Stöger-Pollach, M; Löffler, S; Steiger-Thirsfeld, A; Bliokh, K Y; Nori, Franco

    2014-01-01

    Landau levels and states of electrons in a magnetic field are fundamental quantum entities underlying the quantum Hall and related effects in condensed matter physics. However, the real-space properties and observation of Landau wave functions remain elusive. Here we report the real-space observation of Landau states and the internal rotational dynamics of free electrons. States with different quantum numbers are produced using nanometre-sized electron vortex beams, with a radius chosen to match the waist of the Landau states, in a quasi-uniform magnetic field. Scanning the beams along the propagation direction, we reconstruct the rotational dynamics of the Landau wave functions with angular frequency ~100 GHz. We observe that Landau modes with different azimuthal quantum numbers belong to three classes, which are characterized by rotations with zero, Larmor and cyclotron frequencies, respectively. This is in sharp contrast to the uniform cyclotron rotation of classical electrons, and in perfect agreement with recent theoretical predictions. PMID:25105563

  10. Studies of the Ginzburg-Landau equation

    SciTech Connect

    Rodriguez, J.D.

    1988-01-01

    The turbulence problem is the motivation for the study of reduction of phase space dimension in the Ginzburg-Landau equation. Chaotic solutions to this equation provide a turbulence analog. A basis set for the chaotic attractor is derived using the orthogonal decomposition of the correlation matrix. This matrix is computed explicitly at the point of maximal Liapunov dimension in the parameter range under study. The basis set is shown to be optimal in a least squares sense. Galerdin projection is then used to obtain a small set of O.D.E.'s. The case of spatially periodic, even initial data is studied first. Three complex O.D.E.'s were sufficient to reproduce the solution of the full system as given by a 16 point pseudo-spectral Fourier method. The case of homogeneous boundary conditions was studied next. Ten complex O.D.E.'s were required versus 128 for the pseudo-spectral solution. Using power spectra and Poincare sections the reduced systems were shown to reproduce the exact behavior over a wide parameter range. Savings in C.P.U. time of an order of magnitude were attained over pseudo-spectral algorithms. New results on the asymptotic behavior of limit cycle solutions were also obtained. Singular solutions, zero almost everywhere, with strong boundary layer character were found in the limit of large domain size. An infinite hierarchy of subharmonic solutions was shown to exist for the spatially periodic case, and a countable number of fixed point solutions was found for both spatially periodic and homogeneous cases.

  11. Lehrbuch der Mathematischen Physik

    NASA Astrophysics Data System (ADS)

    Thirring, Walter

    Aus den Besprechungen der ersten Auflage: "... Das Buch wendet sich nicht nur an Studierende der Physik und Mathematik in höheren Semestern, sondern ist auch für fertige Physiker und Mathematiker äußerst anregend. Ein besonderes Lob möchte ich für die zahlreichen Illustrationen des Stoffes mit relevanten, anwendungsbezogenen Beispielen aussprechen." Zeitschrift für Angewandte Mathematik und Physik#1 "W. Thirring hat mit seinem Lehrbuch für Mathematische Physik das erstemal den Versuch unternommen, eine spezifische Bearbeitung der gesamten mathematischen Physik einzuleiten und damit ein "Lehrbuch" der wissenschaftlichen Fachwelt vorzulegen, das in seiner Art sicher als neuartig zu bezeichnen ist. Es zeigt neben der Klarheit und Übersichtlichkeit aber auch eine tiefe Kenntnis der Pädagogik, um ein so schwieriges und abstraktes Gebiet darzustellen." Acta Physica Austriaca#2 "Der Leser kann hier Mathematische Physik in einer Form kennenlernen, wie sie sich einem in der akutuellen Forschung stehenden theoretischen Physiker darstellt, der andererseits auch mit der Entwicklung der modernen mathematischen Methoden wohlvertraut ist. Trotz der anspruchsvollen mathematischen Fundierung gerät der Verfasser an keiner Stelle des Buches in die Gefahr, Mathematische Physik im Sinne einer rein mathematischen Disziplin zu verfremden ... Wer heute wissen will, was "Mathematische Physik" ist und sein soll, wird an diesem Buch nicht vorbeigehen können und Antwort und Gewinn davontragen..." ZAMM#3

  12. Lehrbuch der Mathematischen Physik

    NASA Astrophysics Data System (ADS)

    Thirring, Walter

    Aus den Besprechungen der ersten Auflage: "...Das Buch wendet sich nicht nur an Studierende der Physik und Mathematik in höheren Semestern, sondern ist auch für fertige Physiker und Mathematiker äußerst anregend. Ein besonderes Lob möchte ich für die zahlreichen Illustrationen des Stoffes mit relevanten, anwendungsbezogenen Beispielen aussprechen." Zeitschrift für Angewandte Mathematik und Physik#1 "...W. Thirring hat mit seinem Lehrbuch für mathematische Physik das erstemal den Versuch unternommen, eine spezifische Bearbeitung der gesamten mathematischen Physik einzuleiten und damit ein 'Lehrbuch' der wissenschaftlichen Fachwelt vorzulegen, das in seiner Art sicher als neuartig zu bezeichnen ist. Es zeigt neben der Klarheit und Übersichtlichkeit aber auch eine tiefe Kenntnis der Pädagogik, um ein so schwieriges und abstraktes Gebiet darzustellen..." Acta Physica Austriaca#2 "... Der Leser kann hier Mathematische Physik in einer Form kennenlernen, wie sie sich einem in der aktuellen Forschung stehenden theoretischen Physiker darstellt, der andererseits auch mit der Entwicklung der modernen mathematischen Methoden wohlvertraut ist. Trotz der anspruchsvollen mathematischen Fundierung gerät der Verfasser an keiner Stelle des Buches in die Gefahr, Mathematische Physik im Sinne einer rein mathematischen Disziplin zu verfremden...Wer heute wissen will, was 'Mathematische Physik'ist und sein soll, wird an diesem Buch nicht vorbeigehen können und Antwort und Gewinn davontragen..." ZAMM#3

  13. Geometry of Landau Level without Galilean or Rotational Symmetry

    NASA Astrophysics Data System (ADS)

    Shen, Yu; Haldane, F. D. M.

    The integer quantum Hall effect is usually modeled using Galilean-invariant or rotationally-invariant Landau levels. However, these are not generic symmetries of electrons moving in a crystalline background. We explicitly break both symmetries by considering a inversion-symmetric Hamiltonian with quartic terms. We carry out exact diagonalization numerically with a truncated Hilbert space, and define an emergent metric gabn for each Landau level as the expectation value of a bilinear form in momentum. With an appropriate choice of the guiding center coherent state, the Landau level wavefunctions are holomorphic functions of z* times a Gaussian (this is distinct from a well-known property of rotationally-invariant lowest-Landau-level wavefunctions). We show that the zeroes of the wavefunction define a ``topological spin sn'', with its original definition as an ``intrinsic angular momentum'' no longer valid without rotational symmetry. This is now related to the number of zeroes n encircled by the classical orbit by sn = n +1/2 . Finally we introduce a mass tensor mabn for each Landau level using a Lagrangian formalism. We conclude that topological and geometric information can be extracted without resort to Galilean or Rotational symmetries. This work is partly supported by DOE Grant No. DE-SC0002140 and the W. M. Keck Foundation.

  14. Pre-acceleration from Landau-Lifshitz series

    NASA Astrophysics Data System (ADS)

    Zhang, Sen

    2013-12-01

    The Landau-Lifshitz equation is considered as an approximation of the Abraham-Lorentz-Dirac equation. It is derived from the Abraham-Lorentz-Dirac equation by treating radiation reaction terms as a perturbation. However, while the Abraham-Lorentz-Dirac equation has pathological solutions of pre-acceleration and runaway, the Landau-Lifshitz equation and its finite higher-order extensions are free of these problems. So it seems mysterious that the properties of the solutions of these two equations are so different. In this paper we show that the problems of pre-acceleration and runaway appear when one considers a series of all-order perturbation which we call the Landau-Lifshitz series. We show that the Landau-Lifshitz series diverges in general. Hence a resummation is necessary to obtain a well-defined solution from the Landau-Lifshitz series. This resummation leads the pre-accelerating and the runaway solutions. The analysis focuses on the non-relativistic case, but we can extend the results obtained here to the relativistic case, at least in one dimension.

  15. Grundlagen der Mechatronik

    NASA Astrophysics Data System (ADS)

    Roddeck, Werner

    Der Begriff Mechatronik ist ein Kunstwort, welches durch Eindeutschung des englischen Wortes "Mechatronics“ entstanden ist. Dieses ist wiederum eine Zusammenziehung der englischen Bezeichnungen für "Mechanics“ (Maschinenbau) und "Electronics“ (Elektrotechnik). Der Begriff wurde durch einen japanischen Ingenieur 1969 geprägt und durch eine japanische Firma bis 1972 als Warenzeichen gehalten.

  16. Der II. Hauptsatz der Wärmelehre

    NASA Astrophysics Data System (ADS)

    Heintze, Joachim

    Wir haben in (4.44) den II. Hauptsatz als empirische Tatsache folgendermaßen formuliert: (i) Wärmeenergie geht von selbst nur von einem wärmeren Körper auf einen kälteren über, niemals in der umgekehrten Richtung. Nun werden wir beweisen, dass sich aus diesem Prinzip folgende äquivalente Formulierungen für den II. Hauptsatz ableiten lassen: (ii) Es ist unmöglich, ein Perpetuum mobile zweiter Art zu bauen, d. h. eine Maschine, die fortlaufend Wärmeenergie vollständig in mechanische Arbeit umsetzen kann. Eine Wärmekraftmaschine, die einen Kreisprozess mit der höchsten Temperatur Tw und der niedrigsten Temperatur Tk durchläuft, hat höchstens den Carnotschen Wirkungsgrad c = (Tw - Tk)/Tw. Wenn in der Maschine nur reversible Prozesse ablaufen, die gesamte Wärmezufuhr bei der Temperatur Tw erfolgt und ausschließlich bei der Temperatur Tw gekühlt wird, ist ihr Wirkungsgrad = C. Es gibt keine Wärmekraftmaschine, die eine bessere Ausnutzung der Wärmeenergie ermöglicht. (iv) In jedem thermodynamischen System existiert die Zustandsgröße Entropie, definiert durch ihr Differential dS = (dQrev)/T . Entropie kann erzeugt, aber nicht vernichtet werden. Bei Zustandsänderungen, die in einem abgeschlossenen System ablaufen, nimmt die Entropie entweder zu (irreversible Prozesse), oder sie bleibt konstant (reversible Prozesse). Im Anschluss an (iii) werden wir zur Definition der thermodynamischen Temperatur und bei der Diskussion von (iv) zu einem tieferen Verständnis der Entropie gelangen. Es zeigt sich, dass die Entropie das eigentliche Bindeglied zwischen Mechanik und Wärmelehre darstellt. Am Ende des Kapitels werden wir einige Anwendungen des II. Hauptsatzes betrachten.

  17. Fermion-induced quantum critical points: beyond Landau criterion

    NASA Astrophysics Data System (ADS)

    Yao, Hong; Li, Zi-Xiang; Jiang, Yi-Fan; Jian, Shao-Kai

    According to Landau criterion, phase transitions must be first-order when cubic terms of order parameters in the Landau-Ginzburg free energy are allowed by symmetry. Here, from both renormalization group analysis and sign-problem-free quantum Monte Carlo simulations, we show that second-order quantum phase transitions can occur at such putatively-first-order quantum phase transitions in strongly-interacting Dirac semimetals in two spatial dimensions. Such type of Landau-criterion-violating quantum critical points are induced by massless fermionic modes at the quantum phase transitions. We call them ``fermion-induced quantum critical points''. From Majorana-quantum-Monte-Carlo simulations and renormalization analysis, we find that the critical exponentials at the kekule valence-bond-solid transition of the Dirac fermions on the honeycomb lattice are highly-nonclassical. We also discuss experimental signatures of the kekule quantum critical point which may be realized in graphene-like systems.

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

    PubMed

    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. PMID:27152821

  19. Landau levels of Majorana fermions in a spin liquid

    NASA Astrophysics Data System (ADS)

    Rachel, Stephan; Fritz, Lars; Vojta, Matthias

    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 pseudo-magnetic field. We show that measuring the dynamic spin susceptibility reveals the Landau-level structure by a remarkable mechanism of probe-induced bound-state formation.

  20. Landau Levels of Majorana Fermions in a Spin Liquid

    NASA Astrophysics Data System (ADS)

    Rachel, Stephan; Fritz, Lars; Vojta, Matthias

    2016-04-01

    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.

  1. Nonlinear Landau damping of transverse electromagnetic waves in dusty plasmas

    SciTech Connect

    Tsintsadze, N. L.; Chaudhary, Rozina; Shah, H. A.; Murtaza, G.

    2009-04-15

    High-frequency transverse electromagnetic waves in a collisionless isotropic dusty plasma damp via nonlinear Landau damping. Taking into account the latter we have obtained a generalized set of Zakharov equations with local and nonlocal terms. Then from this coupled set of Zakharov equations a kinetic nonlinear Schroedinger equation with local and nonlocal nonlinearities is derived for special cases. It is shown that the modulation of the amplitude of the electromagnetic waves leads to the modulation instability through the nonlinear Landau damping term. The maximum growth rate is obtained for the special case when the group velocity of electromagnetic waves is close to the dust acoustic velocity.

  2. Quantal Description of Atomic Diamagnetism: the Quasi-Landau Resonances

    NASA Astrophysics Data System (ADS)

    Wang, Qiaoling

    We describe atomic hydrogen diamagnetism within the framework of nonrelativistic quantum mechanics. Our theoretical studies have used three descriptions: an adiabatic description, a multichannel quantum defect theory (MQDT) description using an ab initio R-matrix approach, and a model description. The analysis has conclusively demonstrated that the diamagnetic spectrum can be viewed as a perturbed Rydberg spectrum. The adiabatic analysis provides a crude but useful picture to see the overall channel structure and the nature of the perturbing configurations, where the quasi-Landau resonances are the lowest states in each Landau channel which will perturb high Rydberg states in lower Landau channels once the nonadiabatic coupling is turned on. The ab initio calculation of the photoionization spectrum in the field range 10^3 -10^4 Tesla shows that the quasi -Landau resonances are broad interlopers which perturb high Rydberg states converging to the Landau thresholds, forming complex resonances. Also in these calculations, a new partial cross section analysis has been performed to predict the relative electron populations in different Landau channels. The population is found to depend on the azimuthal quantum number and the parity of final states. For photoionization from the hydrogen ground state of final states with m = 1, the electron is predicted to escape predominantly in the higher Landau channels. In contrast, for the final states with m = 0, it escapes in the lower channels. This property is reflected in the shape of autoionizing resonances, which are more like peaks for m = 1, but are more like dips (window resonances) for m = 0. In studying the features of the complex resonances, formed by the quasi-Landau resonances perturbing the high Rydberg states, we developed an analytical description using a model based on three interacting Rydberg channels, identifying the key dynamical quantities which control the appearance of a complex resonance and its evolution

  3. Determining nodes for the Ginzburg-Landau equations of superconductivity.

    SciTech Connect

    Kaper, H. G.; Wang, B.; Wang, S.; Mathematics and Computer Science; Tsinghua Univ.; Indiana Univ.

    1998-04-01

    It is shown that a solution of the time-independent Ginsburg-Landau equations of superconductivity is determined completely and exactly by its values at a finite but sufficiently dense set of determining nodes in the domain. If the applied magnetic field is time dependent and asymptotically stationary, the large-time asymptotic behavior of a solution of the time-dependent Ginsburg-Landau equations of superconductivity is determined similarly by its values at a finite set of determining nodes, whose positions may vary with time.

  4. Nielsen-Olesen vortices for large Ginzburg-Landau parameter

    NASA Astrophysics Data System (ADS)

    Burzlaff, Jürgen; Navarro-Lérida, F.

    2010-12-01

    Using analytic and numerical techniques Nielsen-Olesen vortices, which in the context of Ginzburg-Landau theory are known as Abrikosov vortices of type-II superconductors, are studied for large Ginzburg-Landau parameter λ. We show that their energy is equal to (πn2/2)log⁡λ to leading order, where n is the winding number of the vortex, and find that the limit of the gauge field can be expressed in terms of the modified Bessel function K1. The leading terms of the asymptotic expansion of the solution are given, and the different contributions to the energy are analyzed.

  5. On Exact Solutions of Novel Multistate Landau-Zener Problems

    NASA Astrophysics Data System (ADS)

    Patra, Aniket; Yuzbashyan, Emil

    A multistate Landau-Zener (MLZ) Hamiltonian is used to model numerous non-equilibrium experiments involving cold atoms, quantum dots and quantum dot molecules. We recently showed that all the known MLZ problems either reduce to the 2 × 2 Landau Zener problem or belong to a family of mutually commuting Hamiltonians (that are polynomial in time). Based on this classification we identify previously unknown MLZ problems, explicitly obtain their solutions and discuss relevant experimental scenarios. Supported in part by the David and Lucile Packard Foundation.

  6. Landau damping in a multi-component dusty plasma

    SciTech Connect

    Zhang, Heng; Yang, Yang; Zhang, Jie; Hong, Xue-Ren; Lin, Mai-Mai; Qi, Xin E-mail: duanws@nwnu.edu.cn; Duan, Wen-Shan E-mail: duanws@nwnu.edu.cn; Yang, Lei

    2014-11-15

    Effect of the dust size distribution on the landau damping and the wave frequency is studied in the present paper. It is found that wave frequency increases as either the difference between the largest and the smallest dust size increases or the wave number increases. It seems that wave frequency is smaller for dusty plasma whose density of the smaller grains is larger than that of the larger ones, while it is larger in the opposite case. The effect of the dust size distribution can increase the Landau damping in the cases where the temperature of the dust grains is small enough or high enough.

  7. A Simple Approach to the Landau-Zener Formula

    ERIC Educational Resources Information Center

    Vutha, Amar C.

    2010-01-01

    The Landau-Zener formula provides the probability of non-adiabatic transitions occurring when two energy levels are swept through an avoided crossing. The formula is derived here in a simple calculation that emphasizes the physics responsible for non-adiabatic population transfer. (Contains 2 figures.)

  8. The Berry Connection of the Ginzburg-Landau Vortices

    NASA Astrophysics Data System (ADS)

    Nagy, Ákos

    2016-06-01

    We analyze 2-dimensional Ginzburg-Landau vortices at critical coupling, and establish asymptotic formulas for the tangent vectors of the vortex moduli space using theorems of Taubes and Bradlow. We then compute the corresponding Berry curvature and holonomy in the large area limit.

  9. Landau damping effects on solar wind fast streams

    NASA Technical Reports Server (NTRS)

    Dangelo, N.; Joyce, G.; Pesses, M. E.

    1979-01-01

    Recent measurements by the Pioneer 10 and Helios 1 spacecraft show that the leading edge of a corotating structure spreads as it moves from 0.3 AU to the orbit of the earth and steepens again farther out. By including Landau damping effects in the dynamical behavior of the streams, the above qualitative features can be accounted for.

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

    SciTech Connect

    Mukherjee, Abhik; Janaki, M. S.; Bose, Anirban

    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.

  11. Notes on the Landau, Pomeranchuk, Midgel effect: Experiment and theory

    SciTech Connect

    Perl, M.L.

    1994-05-01

    The status of the Landau, Pomeranchuk, Migdal Effect is briefly reviewed. A recent experiment at the Stanford Linear Accelerator Center substantially agrees with the existing theoretical formulation. However, that formulation suffers from an imprecise foundation and a lack of generality. The difficulty of finding a simple, explanatory picture of the 1/{radical}K behavior of the Effect is also noted.

  12. Two-dimensional discrete Ginzburg-Landau solitons

    SciTech Connect

    Efremidis, Nikolaos K.; Christodoulides, Demetrios N.; Hizanidis, Kyriakos

    2007-10-15

    We study the two-dimensional discrete Ginzburg-Landau equation. In the linear limit, the dispersion and gain curves as well as the diffraction pattern are determined analytically. In the nonlinear case, families of two-dimensional discrete solitons are found numerically as well as approximately in the high-confinement limit. The instability dynamics are analyzed by direct simulations.

  13. Nonlinear Landau-Zener tunneling in coupled waveguide arrays

    SciTech Connect

    Khomeriki, Ramaz

    2010-07-15

    The possibility of direct observation of the nonlinear Landau-Zener tunneling effect with a device consisting of two waveguide arrays connected to a tilted reduced refractive index barrier is discussed. Numerical simulations on this realistic setup are interpreted via a simplified double-well system and different asymmetric tunneling scenarios are predicted varying just the injected beam intensity.

  14. Fast quantum noise in the Landau-Zener transition

    SciTech Connect

    Pokrovsky, V. L.; Sun, D.

    2007-07-01

    We show by direct calculation starting from a microscopic model that the two-state system with time-dependent energy levels in the presence of fast quantum noise obeys the master equation. The solution of master equation is found analytically and analyzed in a broad range of parameters. The fast transverse noise affects the transition probability during much longer time (the accumulation time) than the longitudinal one. The action of the fast longitudinal noise is restricted by the shorter Landau-Zener time, the same as in the regular Landau-Zener process. The large ratio of time scales allows solving the Landau-Zener problem with longitudinal noise only, and then solving the same problem with the transverse noise only and matching the two solutions. The correlation of the longitudinal and transverse noise renormalizes the Landau-Zener transition matrix element and can strongly enhance the survival probability, whereas the transverse noise always reduces it. If the noise is fast, its intensity at which the multiquantum processes become essential corresponds to a deeply adiabatic regime. We briefly discuss possible applications of the general theory to the molecular magnets.

  15. Kants Theorie der Sonne: Physikgeschichte

    NASA Astrophysics Data System (ADS)

    Jacobi, Manfred

    2005-01-01

    Im Rahmen seiner Kosmogonie entwickelte der junge Immanuel Kant eine Theorie der Sonne. Sie ist ein einzigartiges Zeugnis seiner intuitiven Vorstellungskraft und beweist auch die Leistungsfähigkeit der damaligen, vorwiegend von Newton geprägten Weltsicht. Entstehung, Aufbau und Dynamik der Sonne werden in Kants Theorie ebenso erklärt wie etwa das Phänomen der Sonnenflecken.

  16. Bounce-harmonic Landau Damping of Plasma Waves

    NASA Astrophysics Data System (ADS)

    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 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.

  17. Commensurability condition and fractional quantum Hall effect hierarchy in higher Landau levels

    NASA Astrophysics Data System (ADS)

    Jacak, J.; Jacak, L.

    2015-07-01

    The odd structure of the fractional filling hierarchy, which is referred to as the fractional quantum Hall effect, is studied in higher Landau levels using the commensurability condition. The hierarchy of fillings that are derived in this manner is consistent with the experimental observations in the first three Landau levels. The relative poverty of the fractional structure in higher Landau levels compared with the lowest Landau level is explained using commensurability topological arguments. The commensurability criterion for correlated states specific for higher Landau levels (with n ≥ 1), including also the paired states at half fillings of the spinsubbands of these levels, is formulated.

  18. Ginzburg-Landau theory for multiband superconductors: Microscopic derivation

    NASA Astrophysics Data System (ADS)

    Orlova, N. V.; Shanenko, A. A.; Milošević, M. V.; Peeters, F. M.; Vagov, A. V.; Axt, V. M.

    2013-04-01

    A procedure to derive the Ginzburg-Landau (GL) theory from the multiband BCS Hamiltonian is developed in a general case with an arbitrary number of bands and arbitrary interaction matrix. It combines the standard Gor'kov truncation and a subsequent reconstruction in order to match accuracies of the obtained terms. This reconstruction recovers the phenomenological GL theory as obtained from the Landau model of phase transitions but offers explicit microscopic expressions for the relevant parameters. Detailed calculations are presented for a three-band system treated as a prototype multiband superconductor. It is demonstrated that the symmetry in the coupling matrix may lead to the chiral ground state with the phase frustration, typical for systems with broken time-reversal symmetry.

  19. Gravitational Landau damping for an isotropic cluster of stars

    NASA Technical Reports Server (NTRS)

    Habib, Salman; Kandrup, Henry E.; Yip, Ping F.

    1986-01-01

    The problem of ascertaining the dynamical stability and the existence of Landau damping in static, isotropic 'collisionless' star clusters is addressed. The second-order formalism of Kandrup and Sygnet (1985) is applied to a homogeneous and isotropic plasma, demonstrating formally that the unperturbed configuration will always be stable and that the modes must be purely oscillatory. The form of these modes is explicitly examined, culminating in an analytic expression for the time evolution of the density induced by an initial perturbation. It is shown how these considerations can be adapted trivially to localized, nonradial disturbances of a self-gravitating system of stars. The possible existence of gravitational Landau damping for more generic perturbations is discussed.

  20. On the nature of the Landau-Levich transition

    NASA Astrophysics Data System (ADS)

    Delon, Giles

    2005-11-01

    A solid plate can be wetted dynamically by a non-wetting liquid when withdrawn from a bath above a threshold velocity. Landau and Levich described long ago the scaling relation giving the thickness of the entrained film. However the nature of the transition from a static meniscus to the Landau-Levich remained unclear. We demonstrate experimentally and theoretically that liquid entrainment occurs due to the nucleation of a solitary wave, well below the critical point corresponding to the disappearance of stationary meniscus solutions. It has been suggested by Golestanian and Raphael that the dynamically forced wetting transition is critical with diverging time scales. This critical behavior is actually avoided by the development of the remarkable ridge-like front that does not trivially match to the liquid reservoir. The macroscopic properties of this ridge are governed by stress balance at molecular scale, and provide a novel, sensitive probe to unravel the singularity at the contact line.

  1. Anticipated synchronization in coupled complex Ginzburg-Landau systems.

    PubMed

    Ciszak, Marzena; Mayol, Catalina; Mirasso, Claudio R; Toral, Raul

    2015-09-01

    We study the occurrence of anticipated synchronization in two complex Ginzburg-Landau systems coupled in a master-slave configuration. Master and slave systems are ruled by the same autonomous function, but the slave system receives the injection from the master and is subject to a negative delayed self-feedback loop. We give evidence that the magnitude of the largest anticipation time, obtained for complex-valued coupling constants, depends on the dynamical regime where the system operates (defect turbulence, phase turbulence, or bichaos) and scales with the linear autocorrelation time of the system. We also provide analytical conditions for the stability of the anticipated synchronization manifold that are in qualitative agreement with those obtained numerically. Finally, we report on the existence of anticipated synchronization in coupled two-dimensional complex Ginzburg-Landau systems. PMID:26465544

  2. Anticipated synchronization in coupled complex Ginzburg-Landau systems

    NASA Astrophysics Data System (ADS)

    Ciszak, Marzena; Mayol, Catalina; Mirasso, Claudio R.; Toral, Raul

    2015-09-01

    We study the occurrence of anticipated synchronization in two complex Ginzburg-Landau systems coupled in a master-slave configuration. Master and slave systems are ruled by the same autonomous function, but the slave system receives the injection from the master and is subject to a negative delayed self-feedback loop. We give evidence that the magnitude of the largest anticipation time, obtained for complex-valued coupling constants, depends on the dynamical regime where the system operates (defect turbulence, phase turbulence, or bichaos) and scales with the linear autocorrelation time of the system. We also provide analytical conditions for the stability of the anticipated synchronization manifold that are in qualitative agreement with those obtained numerically. Finally, we report on the existence of anticipated synchronization in coupled two-dimensional complex Ginzburg-Landau systems.

  3. Comments on Landau damping due to synchrotron frequency spread

    SciTech Connect

    Ng, K.Y.; /Fermilab

    2005-01-01

    An inductive/space-charge impedance shifts the synchrotron frequency downwards above/below transition, but it is often said that the coherent synchrotron frequency of the bunch is not shifted in the rigid-dipole mode. On the other hand, the incoherent synchrotron frequency due to the sinusoidal rf always spreads in the downward direction. This spread will therefore not be able to cover the coherent synchrotron frequency, implying that there will not be any Landau damping no matter how large the frequency spread is. By studying the dispersion relation, it is shown that the above argument is incorrect, and there will be Landau damping if there is sufficient frequency spread. The main reason is that the coherent frequency of the rigid-dipole mode will no longer remain unshifted in the presence of a synchrotron frequency spread.

  4. Generalized chaotic synchronization in coupled Ginzburg-Landau equations

    SciTech Connect

    Koronovskii, A. A. Popov, P. V. Hramov, A. E.

    2006-10-15

    Generalized synchronization is analyzed in unidirectionally coupled oscillatory systems exhibiting spatiotemporal chaotic behavior described by Ginzburg-Landau equations. Several types of coupling between the systems are analyzed. The largest spatial Lyapunov exponent is proposed as a new characteristic of the state of a distributed system, and its calculation is described for a distributed oscillatory system. Partial generalized synchronization is introduced as a new type of chaotic synchronization in spatially nonuniform distributed systems. The physical mechanisms responsible for the onset of generalized chaotic synchronization in spatially distributed oscillatory systems are elucidated. It is shown that the onset of generalized chaotic synchronization is described by a modified Ginzburg-Landau equation with additional dissipation irrespective of the type of coupling. The effect of noise on the onset of a generalized synchronization regime in coupled distributed systems is analyzed.

  5. Landau damping in a collisionless dipolar Bose gas

    NASA Astrophysics Data System (ADS)

    Natu, Stefan S.; Wilson, Ryan M.

    2013-12-01

    We present a theory for the Landau damping of low-energy quasiparticles in a collisionless, quasi-two-dimensional dipolar Bose gas and produce expressions for the damping rate in uniform and nonuniform systems. Using simple energy-momentum conservation arguments, we show that in the homogeneous system, the nature of the low-energy dispersion in a dipolar Bose gas severely inhibits Landau damping of long wavelength excitations. For a gas with contact and dipolar interactions, the damping rate for phonons tends to decrease with increasing dipolar interactions; for strong dipole-dipole interactions, phonons are virtually undamped over a broad range of temperature. The damping rate for maxon-roton excitations is found to be significantly larger than the damping rate for phonons.

  6. Strahlungsfeldbedingungen bei der Ionisationsdosimetrie

    NASA Astrophysics Data System (ADS)

    Krieger, Hanno

    Bei der Dosimetrie von Photonenstrahlungen mit luftgefüllten Ionisationskammern werden in diesem Kapitel zwei Grenzfälle unterschieden. Der eine Fall ist die Bedingung des so genannten Sekundärelektronengleichwichts im Kammervolumen. In diesem Fall bestimmen ausschließlich die Photonen im Messvolumen die dosimetrische Anzeige. Der zweite Grenzfall ist gegeben, wenn das Luftvolumen und die Kammer das Strahlungsfeld im Phantom so wenig stören, dass der Sekundärelektronenfluss unverändert bleibt. Diese Bedingungen nennt man BRAGG-GRAY-Bedingungen. Beide Grenzfälle sind in der Praxis nur näherungsweise zu verwirklichen. Abweichungen müssen durch entsprechende Korrekturen oder Kalibrierungen berücksichtigt werden.

  7. Midpoint numerical technique for stochastic Landau-Lifshitz-Gilbert dynamics

    NASA Astrophysics Data System (ADS)

    D'Aquino, M.; Serpico, C.; Coppola, G.; Mayergoyz, I. D.; Bertotti, G.

    2006-04-01

    The implicit midpoint time-integration technique is applied to the stochastic Landau-Lifshitz-Gilbert (LLG) equation. The numerical scheme converges to the Stratonovich solution in the limit of vanishing time step. It preserves the magnetization magnitude and the main energy balance properties of the LLG equation independently of the time step. The numerical technique is then applied to the study of superparamagnetic state in a small spheroidal particle, and the numerical results are compared with the theory.

  8. Analytic structure of Landau gauge ghost and gluon propagators

    NASA Astrophysics Data System (ADS)

    Strauss, Stefan; Fischer, Christian S.; Kellermann, Christian

    2012-04-01

    We summarize first explicit results for the analytic structure of the ghost and gluon propagators in the complex momentum plane. To this end we work in Landau gauge and use a truncation of the Dyson-Schwinger equations for the propagators which is close to lattice results at real spacelike Euclidean momenta. Our results indicate the absence of singularities in the complex part of the momentum plane contrary to expectations from Gribov-Zwanziger-like effective theories.

  9. N-body description of Debye shielding and Landau damping

    NASA Astrophysics Data System (ADS)

    Escande, D. F.; Doveil, F.; Elskens, Yves

    2016-01-01

    This paper brings further insight into the recently published N-body description of Debye shielding and Landau damping (Escande et al 2014 Plasma Phys. Control. Fusion 57 025017). Its fundamental equation for the electrostatic potential is derived in a simpler and more rigorous way. Various physical consequences of the new approach are discussed, and this approach is compared with the seminal one by Pines and Bohm (1952 Phys. Rev. 85 338-53).

  10. Gauges for the Ginzburg-Landau equations of superconductivity

    SciTech Connect

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

    1995-12-31

    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.

  11. Landau damping of geodesic acoustic mode in toroidally rotating tokamaks

    SciTech Connect

    Ren, Haijun; Cao, Jintao

    2015-06-15

    Geodesic acoustic mode (GAM) is analyzed by using modified gyro-kinetic (MGK) equation applicable to low-frequency microinstabilities in a rotating axisymmetric plasma. Dispersion relation of GAM in the presence of arbitrary toroidal Mach number is analytically derived. The effects of toroidal rotation on the GAM frequency and damping rate do not depend on the orientation of equilibrium flow. It is shown that the toroidal Mach number M increases the GAM frequency and dramatically decreases the Landau damping rate.

  12. Analytical solutions of Landau (1+1)-dimensional hydrodynamics

    DOE PAGESBeta

    Wong, Cheuk-Yin; Sen, Abhisek; Gerhard, Jochen; Torrieri, Giorgio; Read, Kenneth

    2014-12-17

    To help guide our intuition, summarize important features, and point out essential elements, we review the analytical solutions of Landau (1+1)-dimensional hydrodynamics and exhibit the full evolution of the dynamics from the very beginning to subsequent times. Special emphasis is placed on the matching and the interplay between the Khalatnikov solution and the Riemann simple wave solution at the earliest times and in the edge regions at later times.

  13. Bifurcating vortex solutions of the complex Ginzburg-Landau equation.

    SciTech Connect

    Kaper, H. G.; Takac, P.; Mathematics and Computer Science

    1999-10-01

    It is shown that the complex Ginzburg-Landau (CGL) equation on the real line admits nontrivial 2{pi}-periodic vortex solutions that have 2n simple zeros ('vortices') per period. The vortex solutions bifurcate from the trivial solution and inherit their zeros from the solution of the linearized equation. This result rules out the possibility that the vortices are determining nodes for vortex solutions of the CGL equation.

  14. Analytical Solutions of Landau (1+1)-Dimensional Hydrodynamics

    SciTech Connect

    Sen, Abhisek; Gerhard, Jochen; Torrieri, Giorgio; Read, Jr, Kenneth F

    2014-01-01

    To help guide our intuition, summarize important features, and point out essential elements, we review the analytical solutions of Landau (1+1)-dimensional hydrodynamics and exhibit the full evolution of the dynamics from the very beginning to subsequent times. Special emphasis is placed on the matching and the interplay between the Khalatnikov solution and the Riemann simple wave solution at the earliest times and in the edge regions at later times.

  15. Landau damping of space-charge dominated Fermilab Booster beam

    SciTech Connect

    Ng, K.Y.; /Fermilab

    2008-09-01

    The stable region of the Fermilab Booster beam in the complex coherent-tune-shift plane appears to have been shifted far away from the origin by its intense space-charge making Landau damping impossible. However, it is shown that the bunching structure of the beam reduces the mean space-charge tune shift. As a result, the beam can be stabilized by suitable octupole-driven tune spread.

  16. Driven quantum tunneling and pair creation with graphene Landau levels

    NASA Astrophysics Data System (ADS)

    Gagnon, Denis; Fillion-Gourdeau, François; Dumont, Joey; Lefebvre, Catherine; MacLean, Steve

    2016-05-01

    Driven tunneling between graphene Landau levels is theoretically linked to the process of pair creation from vacuum, a prediction of quantum electrodynamics (QED). Landau levels are created by the presence of a strong, constant, quantizing magnetic field perpendicular to a graphene monolayer. Following the formal analogy between QED and the description of low-energy excitations in graphene, solutions of the fully interacting Dirac equation are used to compute electron-hole pair creation driven by a circularly or linearly polarized field. This is achieved via the coupled channel method, a numerical scheme for the solution of the time-dependent Dirac equation in the presence of bound states. The case of a monochromatic driving field is first considered, followed by the more realistic case of a pulsed excitation. We show that the pulse duration yields an experimental control parameter over the maximal pair yield. Orders of magnitude of the pair yield are given for experimentally achievable magnetic fields and laser intensities weak enough to preserve the Landau level structure.

  17. The half-filled Landau level and topological insulator surfaces

    NASA Astrophysics Data System (ADS)

    Senthil, T.

    The metallic state of the half-filled Landau level - described originally in pioneering work by Halperin , Lee, and Read as a liquid of composite fermions - was proposed recently by Son to be described by a particle-hole symmetric effective field theory distinct from that in the prior literature. This talk will develop a simple picture of the particle-hole symmetric composite fermion through a modification of older pictures as electrically neutral ``dipolar'' particles. This picture, and the proposed particle-hole symmetric theory, will be further substantiated through a recently developed deep connection between the half-filled Landau level and correlated surface states of certain three dimensional topological insulators. The phenomenology of composite fermi liquids (with or without particle-hole symmetry) will be revisited. It will be shown that their heat/electrical transport dramatically violates the conventional Wiedemann-Franz law but satisfies a modified one. References: 1. Chong Wang and T. Senthil, ``Half-filled Landau Level, Topological Insulator Surfaces, and Three Dimensional Quantum Spin Liquids,'' cond-mat arXiv:1507.08290 (2015).

  18. Classical analog of quasilinear Landau-Zener tunneling.

    PubMed

    Kovaleva, Agnessa; Manevitch, Leonid I

    2012-01-01

    In this paper we develop an analytical framework to study the effect of nonlinearity on irreversible energy transfer in a system of two weakly coupled oscillators with time-dependent parameters, with special attention to an analogy between classical energy transfer and nonadiabatic quantum tunneling. For preciseness, we suppose that a linear oscillator with constant parameters is excited by an initial impulse but a coupled quasilinear oscillator with slowly varying parameters is initially at rest. It is shown that the equations of the slow passage through resonance in this system are identical to quasilinear equations of nonadiabatic Landau-Zener tunneling. Due to revealed equivalence, a recently found analogy between irreversible energy transfer in a classical linear system and conventional linear Landau-Zener tunneling can be extended to quasilinear systems. An explicit analytical solution of the quasilinear problem is found with the help of an iteration procedure, wherein the linear solution is chosen as an initial approximation. Correctness of the constructed approximations is confirmed by numerical simulations. The results presented in this paper, in addition to providing an analytical framework for understanding the transient dynamics of coupled oscillators, suggest an approximate procedure for solving the quasilinear Landau-Zener equations with arbitrary initial conditions over a finite time interval. PMID:22400638

  19. A Landau fluid model for dissipative trapped electron modes

    SciTech Connect

    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.

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

    SciTech Connect

    Klaczynski, Lutz; Kreimer, Dirk

    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.

  1. Theoretische Konzepte der Physik

    NASA Astrophysics Data System (ADS)

    Longair, Malcolm S.; Simon, B.; Simon, H.

    "Dies ist kein Lehrbuch der theoretischen Physik, auch kein Kompendium der Physikgeschichte ... , vielmehr eine recht anspruchsvolle Sammlung historischer Miniaturen zur Vergangenheit der theoretischen Physik - ihrer "Sternstunden", wenn man so will. Frei vom Zwang, etwas Erschöpfendes vorlegen zu müssen, gelingt dem Autor etwas Seltenes: einen "lebendigen" Zugang zum Ideengebäude der modernen Physik freizulegen, ... zu zeigen, wie Physik in praxi entsteht... Als Vehikel seiner Absichten dienen dem Autor geschichtliche Fallstudien, insgesamt sieben an der Zahl. Aus ihnen extrahiert er das seiner Meinung nach Lehrhafte, dabei bestrebt, mathematische Anachronismen womöglich zu vermeiden... Als Student hätte ich mir diese gescheiten Essays zum Werden unserer heutigen physikalischen Weltsicht gewünscht. Sie sind originell, didaktisch klug und genieren sich auch nicht, von der Faszination zu sprechen, die ... von der Physik ausgeht. Unnötig darauf hinzuweisen, das sie ein gründliches "konventionelles" Studium weder ersetzen wollen noch können, sie vermögen aber, dazu zu ermuntern." #Astronomische Nachrichten (zur englischen Ausgabe)#1

  2. Nomogramme der Sickerwasserprognose

    NASA Astrophysics Data System (ADS)

    Schneider, Wilfried; Stöfen, Heinke

    Kurzfassung Modelle zur Sickerwasserprognose stehen in unterschiedlicher Komplexität zur Verfügung. Komplexe Modelle werden aufgrund der schwierigen Handhabung und des enormen Eingabedatenumfangs in der Praxis kaum angewandt. Grobe Abschätzmethoden sind dagegen nicht ausreichend wissenschaftlich fundiert, um damit justiziable Ergebnisse erzielen zu können. Um die Kluft zwischen komplexer und einfacher, jedoch justiziabler sowie wissenschaftlich fundierter Methode zu schmälern, wurden Nomogramme für Sickerwasserprognosen zur Berücksichtigung der Endlichkeit der Quelle entwickelt. Mithilfe der Nomogramme können ohne Modellierungserfahrung schnell und einfach die zu erwartenden Schadstoffkonzentrationen am Ort der Beurteilung abgeschätzt werden, falls die Endlichkeit der Quelle der hauptsächlich zur Abminderung führende Prozess ist. Die Nomogramme basieren auf analytischen Lösungen der eindimensionalen Advektions-Dispersions-Gleichung. Sie berücksichtigen die Prozesse Advektion, Diffusion in Bodenwasser und -luft, Dispersion, lineare Sorption, Abbau 1. Ordnung innerhalb einer aus mehreren Bodenschichten bestehenden Sickerwasserzone, wobei die Endlichkeit der Schadstoffmasse in der Bodenkontamination einbezogen wird. Die Genauigkeit der Nomogramme wird dargestellt. Models of different complexity are available for groundwater risk assessment. In practice complex models are hardly used, due to their difficult handling and large data requirement. Rough estimation methods are not sufficiently scientifically founded to produce justiciable results. To reduce the gap between complex and easy to use but justiciable and scientifically founded methods we developed nomograms for groundwater risk assessment which take into account the finite mass of contaminant in the source. With the help of the nomograms the expected concentrations at the point of compliance (transition between the unsaturated and saturated zone) can be estimated easily, fast and without any

  3. Geologie der terrestrischen Planeten und Monde.

    NASA Astrophysics Data System (ADS)

    Stöffler, D.

    Contents: 1. Inhalt und Aufgabe der Planetologie. 2. Aufbau des Sonnensystems. 3. Methoden der Exploration und Analyse der Planeten und Monde. 4. Geologische Grundprozesse auf den terrestrischen Planeten und Monden. 5. Geologische Formationen der planetaren Oberflächen. 6. Gesteine und Mineralien der planetaren Krusten. 7. Der innere Aufbau der terrestrischen planetaren Körper. 8. Vergleichende geologische Entwicklungsgeschichte der terrestrischen Planeten und des Mondes. 9. Ursprung und Entstehung der terrestrischen planetaren Körper.

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

    NASA Astrophysics Data System (ADS)

    Dennen, Tristan; Spradlin, Marcus; Volovich, Anastasia

    2016-03-01

    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.

  5. Measurement of Landau damping and the evolution to a BGK equilibrium.

    PubMed

    Danielson, J R; Anderegg, F; Driscoll, C F

    2004-06-18

    Linear Landau damping and nonlinear wave-particle trapping oscillations are observed with standing plasma waves in a trapped pure electron plasma. For low wave amplitudes, the measured linear damping rate agrees quantitatively with linear Landau damping theory. At larger amplitudes, the wave initially damps at the Landau rate, then regrows and oscillates, approaching a steady state, as predicted by O'Neil in 1965 [Phys. Fluids 8, 2255 (1965)

  6. Dissipation in small systems: Landau-Zener approach.

    PubMed

    Barra, Felipe; Esposito, Massimiliano

    2016-06-01

    We establish a stochastic thermodynamics for a Fermionic level driven by a time-dependent force and interacting with initially thermalized levels playing the role of a reservoir. The driving induces consecutive avoided crossings between system and reservoir levels described within Landau-Zener theory. We derive the resulting system dynamics and thermodynamics and identify energy, work, heat, entropy, and dissipation. Our theory perfectly reproduces the numerically exact quantum work statistics obtained using a two point measurements approach of the total energy and provides an explicit expression for the dissipation in terms of diabatic transitions. PMID:27415219

  7. The Landau-Lifshitz equation in atomistic models

    NASA Astrophysics Data System (ADS)

    Ellis, M. O. A.; Evans, R. F. L.; Ostler, T. A.; Barker, J.; Atxitia, U.; Chubykalo-Fesenko, O.; Chantrell, R. W.

    2015-09-01

    The Landau-Lifshitz (LL) equation, originally proposed at the macrospin level, is increasingly used in Atomistic Spin Dynamic (ASD) models. These models are based on a spin Hamiltonian featuring atomic spins of fixed length, with the exchange introduced using the Heisenberg formalism. ASD models are proving a powerful approach to the fundamental understanding of ultrafast magnetization dynamics, including the prediction of the thermally induced magnetization switching phenomenon in which the magnetization is reversed using an ultra-fast laser pulse in the absence of an externally applied field. This paper outlines the ASD model approach and considers the role and limitations of the LL equation in this context.

  8. Realization of geometric Landau-Zener-Stückelberg interferometry

    NASA Astrophysics Data System (ADS)

    Zhang, Junhua; Zhang, Jingning; Zhang, Xiang; Kim, Kihwan

    2014-01-01

    We report an experimental realization of the geometric Landau-Zener-Stückelberg (LZS) interferometry proposed by Gasparinetti et al. [Phys. Rev. Lett. 107, 207002 (2011), 10.1103/PhysRevLett.107.207002] in a single-trapped-ion system. Unlike those in a conventional LZS interferometer, the interference fringes of our geometric interferometer originate solely from a geometric phase. We also observe the robustness of the interference contrast against noise or fluctuations in the experimental parameters. Our scheme can be applied to other complex systems subject to relatively large errors in system control.

  9. Periodic solutions for the Landau-Lifshitz-Gilbert equation

    NASA Astrophysics Data System (ADS)

    Huber, Alexander

    2011-03-01

    Ferromagnetic materials tend to develop very complex magnetization patterns whose time evolution is modeled by the so-called Landau-Lifshitz-Gilbert equation (LLG). In this paper, we construct time-periodic solutions for LLG in the regime of soft and small ferromagnetic particles which satisfy a certain shape condition. Roughly speaking, it is assumed that the length of the particle is greater than its hight and its width. The approach is based on a perturbation argument and the spectral analysis of the corresponding linearized problem as well as the theory of sectorial operators.

  10. Adaptive techniques for Landau-Lifshitz-Gilbert equation with magnetostriction

    NASA Astrophysics Data System (ADS)

    Banas, L'ubomir

    2008-06-01

    In this paper we propose a time-space adaptive method for micromagnetic problems with magnetostriction. The considered model consists of coupled Maxwell's, Landau-Lifshitz-Gilbert (LLG) and elastodynamic equations. The time discretization of Maxwell's equations and the elastodynamic equation is done by backward Euler method, the space discretization is based on Whitney edge elements and linear finite elements, respectively. The fully discrete LLG equation reduces to an ordinary differential equation, which is solved by an explicit method, that conserves the norm of the magnetization.

  11. Hydrodynamic Stability of Liquid-Propellant Combustion: Landau's Problem Revisited

    NASA Technical Reports Server (NTRS)

    Margolis, S. B.

    2001-01-01

    Hydrodynamic, or Landau, instability in combustion is typically associated with the onset of wrinkling of a flame surface, corresponding to the formation of steady cellular structures as the stability threshold is crossed. As its name suggests, it stems from hydrodynamic effects connected with thermal expansion across the reaction region. In the context of liquid-propellant combustion, the classical models that originally predicted this phenomenon have been extended to include the important effects that arise from a dynamic dependence of the burning rate on the local pressure and temperature fields. Thus, the onset of Landau instability has now been shown to occur for sufficiently small negative values of the pressure sensitivity of the burning rate, significantly generalizing previous classical results for this problem that assumed a constant normal burning rate. It has also been shown that the onset of instability occurs for decreasing values of the disturbance wave number as the gravitational-acceleration parameter decreases. Consequently, in an appropriate weak-gravity limit, Landau instability becomes a long-wave phenomena associated with the formation of large cells on the liquid-propellant surface. Additionally, a pulsating form of hydrodynamic instability has been shown to occur as well, corresponding to the onset of temporal oscillations in the location of the liquid/gas interface. This instability occurs for sufficiently large negative values of the pressure sensitivity, and is enhanced by increasing values of the burning-rate temperature sensitivity. It is further shown that for sufficiently small values of this parameter, there exists a stable range of pressure sensitivities for steady, planar burning such that the classical cellular form of hydrodynamic instability and the more recent pulsating form of hydrodynamic instability can each occur as the corresponding stability threshold is crossed. For larger thermal sensitivities, however, the pulsating

  12. Emergence of frustrated antiferromagnet in the lowest Landau level

    NASA Astrophysics Data System (ADS)

    Rhim, Jun Won; Archer, Alexander C.; Jain, Jainendra K.; Park, Kwon; Condensed Matter Theory Collaboration

    2014-03-01

    We investigate the spin structure of the triangular composite fermion crystals (CFCs) in the lowest Landau level (LLL). In contrast to the usual Hund's rule, our Monte-Carlo (MC) calculation finds the spin exchange energy to be antiferromagnetic in certain parameter regimes in the vicinity of ν = 1 / 5 . For further physical intuition, we develop an effective two-body potential between composite fermions in the crystal phase, which provides a reasonable account of the MC results. We discuss the experimental feasibility of this physics.

  13. Ginzburg-Landau functional for three order parameter problem

    NASA Astrophysics Data System (ADS)

    Van Hinh, Nguyen; Lan, Nguyen Tri

    2016-06-01

    A model is presented utilizing a generic Hamiltonian with equal pairings in channels based on quantum field theory and functional integral formalism, to show the correlation among the order parameters which are described in multi-component Ginzburg-Landau functional. In the vicinity of the phase transition, the further perturbative expansions of the functional around the mean-field theory in the auxiliary fields are carried out with the aim of leading to a possible solution for the coexistence of many phases. The work is motivated by the recent theoretical researches and experimental evidences of the coexistence of superconductivity and ferromagnetism in U and Ce compounds.

  14. On the Landau system in noncommutative phase-space

    NASA Astrophysics Data System (ADS)

    Gangopadhyay, Sunandan; Saha, Anirban; Halder, Aslam

    2015-12-01

    We consider the Landau system in a canonically noncommutative phase-space. A set of generalized transformations containing scaling parameters is derived which maps the NC problem to an equivalent commutative problem. The energy spectrum admits NC corrections which are computed using the explicit NC variables as well as the commutative-equivalent variables. Their exact matching solidifies the evidence of the equivalence of the two approaches. We also obtain the magnetic length and level degeneracy, which admit NC corrections. We further study the Aharonov-Bohm effect where the phase-shift is found to alter due to noncommutativity and also depends on the scaling parameters.

  15. Collisional width of giant resonances and interplay with Landau damping

    SciTech Connect

    Bonasera, A.; Burgio, G. F.; Di Toro, M.; Wolter, H. H.

    1989-06-01

    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.

  16. Analytic Structure of the Landau-Gauge Gluon Propagator

    NASA Astrophysics Data System (ADS)

    Strauss, Stefan; Fischer, Christian S.; Kellermann, Christian

    2012-12-01

    The analytic structure of the nonperturbative gluon propagator contains information on the absence of gluons from the physical spectrum of the theory. We study this structure from numerical solutions in the complex momentum plane of the gluon and ghost Dyson-Schwinger equations in Landau gauge Yang-Mills theory. The resulting ghost and gluon propagators are analytic apart from a distinct cut structure on the real, timelike momentum axis. The propagator violates the Osterwalder-Schrader positivity condition, confirming the absence of gluons from the asymptotic spectrum of the theory.

  17. Analytic structure of the Landau-gauge gluon propagator.

    PubMed

    Strauss, Stefan; Fischer, Christian S; Kellermann, Christian

    2012-12-21

    The analytic structure of the nonperturbative gluon propagator contains information on the absence of gluons from the physical spectrum of the theory. We study this structure from numerical solutions in the complex momentum plane of the gluon and ghost Dyson-Schwinger equations in Landau gauge Yang-Mills theory. The resulting ghost and gluon propagators are analytic apart from a distinct cut structure on the real, timelike momentum axis. The propagator violates the Osterwalder-Schrader positivity condition, confirming the absence of gluons from the asymptotic spectrum of the theory. PMID:23368451

  18. Applying modified Ginzburg-Landau theory to nuclei

    NASA Astrophysics Data System (ADS)

    Mohammadi, P.; Dehghani, V.; Mehmandoost-Khajeh-Dad, A. A.

    2014-11-01

    The Ginzburg-Landau theory of phase transitions is modified and used to investigate the heat capacity, energy, entropy, and order parameter of the paired phases of 208Pb,88Sr,48Ca, and 20Ne. We use the Fermi gas model to calculate the thermodynamic properties of the normal phase of the nucleons. Our results show that the total heat capacities of the studied nuclei have an S -shape behavior, which is in accordance with the semi-empirical data, and the order parameter does not approach zero at a specific critical temperature.

  19. Continuous-wave lasing between Landau levels in graphene

    NASA Astrophysics Data System (ADS)

    Wang, Yongrui; Tokman, Mikhail; Belyanin, Alexey

    2015-03-01

    We predict the general feasibility and demonstrate the design of the continuous-wave terahertz laser operating between Landau levels in graphene placed on a polar substrate in a magnetic field of order 1 T. Steady-state population inversion under a continuous-wave optical pumping becomes possible due to surface-phonon-mediated relaxation of carriers. The scheme is scalable to other materials with massless Dirac fermions, for example, surface states in three-dimensional topological insulators such as Bi2Se3 or Bi2Te3 .

  20. The Saga of Landau-Gauge Propagators: Gathering New Ammo

    NASA Astrophysics Data System (ADS)

    Cucchieri, Attilio; Mendes, Tereza

    2011-05-01

    Compelling evidence has recently emerged from lattice simulations in favor of the massive solution of the Schwinger-Dyson equations of Landau-gauge QCD. The main objections to these lattice results are based on possible Gribov-copy effects. We recently installed at IFSC-USP a new GPU cluster dedicated to the study of Green's functions. We present here our point of view on the Saga and the status of our project. We also show data for the 2D case on a 25602 lattice.

  1. su(1, 1)-Barut Girardello coherent states for Landau levels

    NASA Astrophysics Data System (ADS)

    Fakhri, H.

    2004-05-01

    It is shown that the Hilbert space corresponding to all the quantum states of the Landau problem can be split in two different ways: as infinite direct sums of the finite- and infinite-dimensional representation subspaces of the Lie algebras su(2) and su(1,1) with finite- and infinite-fold degeneracies, respectively. For each of the Hilbert representation subspaces of the Lie algebra su(1,1), we construct a suitable linear combination of its bases as the Barut-Girardello coherent states.

  2. Landau-Zener Transitions in Frozen Pairs of Rydberg Atoms

    SciTech Connect

    Saquet, Nicolas; Cournol, Anne; Beugnon, Jerome; Robert, Jacques; Pillet, Pierre; Vanhaecke, Nicolas

    2010-04-02

    We have induced adiabatic transitions in pairs of frozen Rydberg sodium atoms of a supersonic beam. The diatomic ns+ns{yields}np+(n-1)p transition takes place in a time-dependent electric field and originates from the adiabatic change of the internal state of the pair induced by the dipole-dipole interaction. This is experimentally achieved by sweeping an electric field across the energy degeneracy ns ns-np(n-1)p. Our results fully agree with a two-level Landau-Zener model in the diatom system.

  3. Ginzburg-Landau theory of a holographic superconductor

    NASA Astrophysics Data System (ADS)

    Yin, Lei; Hou, Defu; Ren, Hai-cang

    2015-01-01

    The general Ginzburg-Landau (GL) formulation of a holographic superconductor is developed near the transition temperature in the probe limit for two kinds of conformal dimension. elow the transition temperature, T

  4. Semiclassical Landau quantization of spin-orbit coupled systems

    NASA Astrophysics Data System (ADS)

    Li, Tommy; Horovitz, Baruch; Sushkov, Oleg P.

    2016-06-01

    A semiclassical quantization condition is derived for Landau levels in general spin-orbit coupled systems. This generalizes the Onsager quantization condition via a matrix-valued phase which describes spin dynamics along the classical cyclotron trajectory. We discuss measurement of the matrix phase via magnetic oscillations and electron spin resonance, which may be used to probe the spin structure of the precessing wave function. We compare the resulting semiclassical spectrum with exact results which are obtained for a variety of spin-orbit interactions in two-dimensional systems.

  5. Dissipation in small systems: Landau-Zener approach

    NASA Astrophysics Data System (ADS)

    Barra, Felipe; Esposito, Massimiliano

    2016-06-01

    We establish a stochastic thermodynamics for a Fermionic level driven by a time-dependent force and interacting with initially thermalized levels playing the role of a reservoir. The driving induces consecutive avoided crossings between system and reservoir levels described within Landau-Zener theory. We derive the resulting system dynamics and thermodynamics and identify energy, work, heat, entropy, and dissipation. Our theory perfectly reproduces the numerically exact quantum work statistics obtained using a two point measurements approach of the total energy and provides an explicit expression for the dissipation in terms of diabatic transitions.

  6. The Saga of Landau-Gauge Propagators: Gathering New Ammo

    SciTech Connect

    Cucchieri, Attilio; Mendes, Tereza

    2011-05-23

    Compelling evidence has recently emerged from lattice simulations in favor of the massive solution of the Schwinger-Dyson equations of Landau-gauge QCD. The main objections to these lattice results are based on possible Gribov-copy effects. We recently installed at IFSC-USP a new GPU cluster dedicated to the study of Green's functions. We present here our point of view on the Saga and the status of our project. We also show data for the 2D case on a 2560{sup 2} lattice.

  7. Landau damping of Langmuir waves in non-Maxwellian plasmas

    SciTech Connect

    Ouazene, M.; Annou, R.

    2011-11-15

    As free electrons move in the nearest neighbour ion's potential well, the equilibrium velocity departs from Maxwell distribution. The effect of the non-Maxwellian velocity distribution function (NMVDF) on many properties of the plasma such as the transport coefficients, the kinetic energy, and the degree of ionization is found to be noticeable. A correction to the Langmuir wave dispersion relation is proved to arise due to the NMVDF as well [Phys. Plasmas 17, 052105 (2010)]. The study is extended hereafter to include the effect of NMVDF on the Landau damping of Langmuir wave.

  8. Canonically covariant formulation of Landau's Newtonian superfluid dynamics

    NASA Astrophysics Data System (ADS)

    Carter, B.; Khalatnikov, I. M.

    1993-05-01

    The classical Landau theory of perfect (i.e. conservative) two constituent superfluid dynamics in Newton spacetime is radically reformulated in a canonical presentation that helps to reveal symmetries and conservation properties (notably those of the thermal vorticity and helicity) that are obscured in the traditional treatment. This presentation uses a 4-dimensional terminology that is more concise and elegant than the traditional 3+1 description and that simplifies the description of transformation properties under the action of the Milne group (i.e. the nonlinear generalization of the Galilei group).

  9. Canonically Covariant Formulation of Landau's Newtonian Superfluid Dynamics

    NASA Astrophysics Data System (ADS)

    Carter, B.; Khalatnikov, I. M.

    The classical Landau theory of perfect (i.e. conservative) two-constituent superfluid dynamics in Newton space-time is radically reformulated in a canonical presentation that helps to reveal symmetries and conservation properties (notably those of the thermal vorticity and helicity) that are obscured in the traditional treatment. This presentation uses a four-dimensional terminology that is more concise and elegant than the traditional 3 + 1 description and that simplifies the description of transformation properties under the action of the Milne group (i.e. the nonlinear generalization of the Galilei group).

  10. Resonances due to the Landau-Zener transition

    SciTech Connect

    Tazawa, T. ); Abe, Y. )

    1990-01-01

    We have derived a new useful analytic formula for the {ital T} matrix in the quantum-mechanical perturbation approach within the two-state problem with finite-range coupling which is appropriate for the discussion of the Landau-Zener transition. The resonancelike behaviors were predicted by classical or semiclassical approach in which constant coupling between two adiabatic states was assumed. In the quantum-mechanical approach, inclusion of the effect of reasonable finite-range coupling would not destroy the pattern of the resonancelike structures so much, while the magnitude of the calculated cross section is merely about 10% of that calculated by the semiclassical approach.

  11. Resonant Landau-Zener transitions in a helical magnetic field

    NASA Astrophysics Data System (ADS)

    Wójcik, P.; Adamowski, J.; Wołoszyn, M.; Spisak, B. J.

    2015-06-01

    Spin-dependent electron transport has been studied in magnetic semiconductor waveguides (nanowires) in the helical magnetic field. We have shown that—apart from the well-known conductance dip located at the magnetic field equal to the helical-field amplitude Bh—the additional conductance dips (with zero conductance) appear at a magnetic field different from Bh. This effect occurring in the non-adiabatic regime is explained as resulting from the resonant Landau-Zener transitions between the spin-split subbands.

  12. Landau-Zener transitions in frozen pairs of Rydberg atoms.

    PubMed

    Saquet, Nicolas; Cournol, Anne; Beugnon, Jérôme; Robert, Jacques; Pillet, Pierre; Vanhaecke, Nicolas

    2010-04-01

    We have induced adiabatic transitions in pairs of frozen Rydberg sodium atoms of a supersonic beam. The diatomic ns+ns-->np+(n-1)p transition takes place in a time-dependent electric field and originates from the adiabatic change of the internal state of the pair induced by the dipole-dipole interaction. This is experimentally achieved by sweeping an electric field across the energy degeneracy ns ns-np(n-1)p. Our results fully agree with a two-level Landau-Zener model in the diatom system. PMID:20481882

  13. Nonlinear Landau-Zener tunneling in Majorana's stellar representation

    NASA Astrophysics Data System (ADS)

    Guo, Qiuyi; Liu, Haodi; Zhou, Tianji; Chen, Xu-Zong; Wu, Biao

    2016-06-01

    By representing the evolution of a quantum state with the trajectories of the stars on a Bloch sphere, the Majorana's stellar representation provides an intuitive way to understand quantum motion in a high dimensional projective Hilbert space. In this work we show that the Majorana's representation offers a very interesting and intuitive way to understand the nonlinear Landau-Zener tunneling. In particular, the breakdown of adiabaticity in this tunneling phenomenon can be understood as some of the stars never reaching the south pole. We also establish a connection between the Majorana stars in the second quantized model and the single star in the mean field model by using the reduced density matrix.

  14. Fluid moments of the nonlinear Landau collision operator

    NASA Astrophysics Data System (ADS)

    Hirvijoki, E.; Lingam, M.; Pfefferlé, D.; Comisso, L.; Candy, J.; Bhattacharjee, A.

    2016-08-01

    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.

  15. The Nonlinear Landau Damping Rate of a Driven Plasma Wave

    SciTech Connect

    Benisti, D; Strozzi, D J; Gremillet, L; Morice, O

    2009-08-04

    In this Letter, we discuss the concept of the nonlinear Landau damping rate, {nu}, of a driven electron plasma wave, and provide a very simple, practical, analytic formula for {nu} which agrees very well with results inferred from Vlasov simulations of stimulated Raman scattering. {nu} actually is more complicated an operator than a plain damping rate, and it may only be seen as such because it assumes almost constant values before abruptly dropping to 0. The decrease of {nu} to 0 is moreover shown to occur later when the wave amplitude varies in the direction transverse to its propagation.

  16. Novel electric field effects on Landau levels in graphene.

    PubMed

    Lukose, Vinu; Shankar, R; Baskaran, G

    2007-03-16

    A new effect in graphene in the presence of crossed uniform electric and magnetic fields is predicted. Landau levels are shown to be modified in an unexpected fashion by the electric field, leading to a collapse of the spectrum, when the value of electric to magnetic field ratio exceeds a certain critical value. Our theoretical results, strikingly different from the standard 2D electron gas, are explained using a "Lorentz boost," and as an "instability of a relativistic quantum field vacuum." It is a remarkable case of emergent relativistic type phenomena in nonrelativistic graphene. We also discuss few possible experimental consequence. PMID:17501075

  17. Cauchy Problem and Exponential Stability for the Inhomogeneous Landau Equation

    NASA Astrophysics Data System (ADS)

    Carrapatoso, Kleber; Tristani, Isabelle; Wu, Kung-Chien

    2016-07-01

    This work deals with the inhomogeneous Landau equation on the torus in the cases of hard, Maxwellian and moderately soft potentials. We first investigate the linearized equation and we prove exponential decay estimates for the associated semigroup. We then turn to the nonlinear equation and we use the linearized semigroup decay in order to construct solutions in a close-to-equilibrium setting. Finally, we prove an exponential stability for such a solution, with a rate as close as we want to the optimal rate given by the semigroup decay.

  18. The quark-gluon vertex in Landau gauge QCD: Its role in dynamical chiral symmetry breaking and quark confinement

    NASA Astrophysics Data System (ADS)

    Alkofer, Reinhard; Fischer, Christian S.; Llanes-Estrada, Felipe J.; Schwenzer, Kai

    2009-01-01

    The infrared behavior of the quark-gluon vertex of quenched Landau gauge QCD is studied by analyzing its Dyson-Schwinger equation. Building on previously obtained results for Green functions in the Yang-Mills sector, we analytically derive the existence of power-law infrared singularities for this vertex. We establish that dynamical chiral symmetry breaking leads to the self-consistent generation of components of the quark-gluon vertex forbidden when chiral symmetry is forced to stay in the Wigner-Weyl mode. In the latter case the running strong coupling assumes an infrared fixed point. If chiral symmetry is broken, either dynamically or explicitly, the running coupling is infrared divergent. Based on a truncation for the quark-gluon vertex Dyson-Schwinger equation which respects the analytically determined infrared behavior, numerical results for the coupled system of the quark propagator and vertex Dyson-Schwinger equation are presented. The resulting quark mass function as well as the vertex function show only a very weak dependence on the current quark mass in the deep infrared. From this we infer by an analysis of the quark-quark scattering kernel a linearly rising quark potential with an almost mass independent string tension in the case of broken chiral symmetry. Enforcing chiral symmetry does lead to a Coulomb type potential. Therefore, we conclude that chiral symmetry breaking and confinement are closely related. Furthermore, we discuss aspects of confinement as the absence of long-range van der Waals forces and Casimir scaling. An examination of experimental data for quarkonia provides further evidence for the viability of the presented mechanism for quark confinement in the Landau gauge.

  19. Generalization of Calabi-Yau/Landau-Ginzburg correspondence

    NASA Astrophysics Data System (ADS)

    Eguchi, Tohru; Jinzenji, Masao

    2000-02-01

    We discuss a possible generalization of the Calabi-Yau/Landau-Ginzburg correspondence to a more general class of manifolds. Specifically we consider the Fermat type hypersurfaces MNk: ∑i = 1NXik = 0 in Bbb CBbb PN-1 for various values of k and N. When k < {N}, the 1-loop beta function of the sigma model on MNk is negative and we expect the theory to have a mass gap. However, the quantum cohomology relation σN-1 = const.σk-1 suggests that in addition to the massive vacua there exists a remaining massless sector in the theory if k > 2. We assume that this massless sector is described by a Landau-Ginzburg (LG) theory of central charge c = 3N(1-2/k) with N chiral fields with U(1) charge 1/k. We compute the topological invariants (elliptic genera) using LG theory and massive vacua and compare them with the geometrical data. We find that the results agree if and only if k = even and N = even. These are the cases when the hypersurfaces have a spin structure. Thus we find an evidence for the geometry/LG correspondence in the case of spin manifolds.

  20. Landau-Heisenberg Hamiltonian model for FeRh

    NASA Astrophysics Data System (ADS)

    Derlet, P. M.

    2012-05-01

    An empirical model is developed for the FeRh system with the view of gaining further insight into the first-order antiferromagnetic-ferromagnetic (AFM-FM) and volume phase transition known to occur at 370 K. A volume-per-atom dependent minimal nearest neighbor Landau-Heisenberg Hamiltonian is employed in which longitudinal and transverse moment fluctuations are considered for both the Fe and Rh atoms. As a function of volume-per-atom, the corresponding onsite Landau function coefficients and the nearest-neighbor exchange parameters are fitted directly to a wide range of existing colinear and noncolinear density functional theory calculations. Using a developed Monte Carlo strategy the thermal properties of the AFM and FM phases are investigated, as well as the phase transition. It is found that the model is able to describe well the thermal expansion, heat capacities and the associated entropy increase that accompanies the magnetic/volume phase transition. The model suggests an equally important role for the magnetic and volume fluctuations in driving the phase transition.

  1. Landau-Zener in a continuously measured molecular spin

    NASA Astrophysics Data System (ADS)

    Troiani, Filippo; Affronte, Marco; Thiele, Stephan; Godfrin, Clement; Balestro, Franck; Wernsdorfer, Wolfgang; Klyatskaya, Svetlana; Ruben, Mario

    The dynamics of a quantum system driven through an avoided level crossing represernts a relevant problem in many physical contexts. Here we present a joint theoretical and experimental investigation of a single-molecule magnet (namely, a terbium double-decker complex) in a three-terminal geometry. The Tb spin is driven through an avoided level crossing by a time-dependent magnetic field, and its dynamics is monitored through a continuous measurement of the conductance. The dependence of the spin-reversal probability on the field sweeping rate presents clear deviations from the Landau-Zener formula, which applies to the case of closed systems. The comparison between direct and inverse Landau-Zener transitions points at the dominance of dephasing, with respect to inelastic incoherent processes. The spin dynamics is simulated within a master equation approach. The observed behaviors are reproduced by assuming that dephasing takes place in the basis of the time-dependent Hamiltonian eigenstates. The spin dephasing is traced back to the continuous measurement of the electron spin, and a fundamental role is played by the finite time resolution of the conductance measurement.

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

    PubMed Central

    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

  3. Landau, Case, van Kampen and Collisionless Fluid Closures

    NASA Astrophysics Data System (ADS)

    Joseph, Ilon

    2015-11-01

    Landau damping represents a fundamental paradox within plasma physics. The equations of motion of classical particles and fields are symmetric under time-reversal; yet, the open system formed by integration over velocity space is not invariant and damping results from phase-mixing. Here, it is shown that the Case-van Kampen theorem can be extended to magnetized plasmas: the linear eigenfunctions provide a complete representation of the particle distribution function and exponentially damped and growing eigenmodes must appear in pairs. The numerical Case-van Kampen transformation can performed efficiently in Fourier velocity space and allows fast timescales in the evolution of the system to be treated using exponential integration. On the other hand, fluid moments require integration over velocity space, and, thus, representation of Landau damping requires explicit introduction of the arrow of time through a collisionless damping operator. This operator captures linear phenomena at the cost of damping nonlinear phenomena such as the plasma echo. Numerical comparisons of these two rather different representations will be presented. LLNL-ABS-674917 prepared by LLNL under Contract DE-AC52-07NA27344.

  4. Infrared singularities in Landau gauge Yang-Mills theory

    SciTech Connect

    Alkofer, Reinhard; Huber, Markus Q.; Schwenzer, Kai

    2010-05-15

    We present a more detailed picture of the infrared regime of Landau-gauge Yang-Mills theory. This is done within a novel framework that allows one to take into account the influence of finite scales within an infrared power counting analysis. We find that there are two qualitatively different infrared fixed points of the full system of Dyson-Schwinger equations. The first extends the known scaling solution, where the ghost dynamics is dominant and gluon propagation is strongly suppressed. It features in addition to the strong divergences of gluonic vertex functions in the previously considered uniform scaling limit, when all external momenta tend to zero, also weaker kinematic divergences, when only some of the external momenta vanish. The second solution represents the recently proposed decoupling scenario where the gluons become massive and the ghosts remain bare. In this case we find that none of the vertex functions is enhanced, so that the infrared dynamics is entirely suppressed. Our analysis also provides a strict argument why the Landau-gauge gluon dressing function cannot be infrared divergent.

  5. Topological photonics: an observation of Landau levels for optical photons

    NASA Astrophysics Data System (ADS)

    Schine, Nathan; Ryou, Albert; Sommer, Ariel; Simon, Jonathan

    We present the first experimental realization of a bulk magnetic field for optical photons. By using a non-planar ring resonator, we induce an image rotation on each round trip through the resonator. This results in a Coriolis/Lorentz force and a centrifugal anticonfining force, the latter of which is cancelled by mirror curvature. Using a digital micromirror device to control both amplitude and phase, we inject arbitrary optical modes into our resonator. Spatial- and energy- resolved spectroscopy tracks photonic eigenstates as residual trapping is reduced, and we observe photonic Landau levels as the eigenstates become degenerate. We show that there is a conical geometry of the resulting manifold for photon dynamics and present a measurement of the local density of states that is consistent with Landau levels on a cone. While our work already demonstrates an integer quantum Hall material composed of photons, we have ensured compatibility with strong photon-photon interactions, which will allow quantum optical studies of entanglement and correlation in manybody systems including fractional quantum Hall fluids. This work was supported by DOE, DARPA, and AFOSR.

  6. Topological photonics: an observation of Landau levels for optical photons

    NASA Astrophysics Data System (ADS)

    Schine, Nathan; Ryou, Albert; Sommer, Ariel; Simon, Jonathan

    Creating photonic materials with nontrivial topological characteristics has seen burgeoning interest in recent years; however, a major route to topology, a magnetic field for continuum photons, has remained elusive. We present the first experimental realization of a bulk magnetic field for optical photons. By using a non-planar ring resonator, we induce an image rotation on each round trip through the resonator. This results in a Coriolis/Lorentz force and a centrifugal anticonfining force, the latter of which is cancelled by mirror curvature. Spatial- and energy- resolved spectroscopy tracks photonic eigenstates as residual trapping is reduced, and we observe photonic Landau levels as the eigenstates become degenerate. We will discuss the conical geometry of the resulting manifold for photon dynamics and present a measurement of the local density of states that is consistent with Landau levels on a cone. While our work already demonstrates an integer quantum Hall material composed of photons, we have ensured compatibility with strong photon-photon interactions, which will allow quantum optical studies of entanglement and correlation in manybody systems including fractional quantum Hall fluids. This work was supported by DOE, DARPA, and AFOSR.

  7. The healing lengths in two-band superconductors in extended Ginzburg-Landau theory

    NASA Astrophysics Data System (ADS)

    Komendová, L.; Shanenko, A. A.; Milošević, M. V.; Peeters, F. M.

    2012-09-01

    We study the vortex profiles in two-gap superconductors using the extended Ginzburg-Landau theory. The results shed more light on the disparity between the effective length scales in two bands. We compare the behavior expected from the standard Ginzburg-Landau theory with this new approach, and find good qualitative agreement in the case of LiFeAs.

  8. An equivalence relation for the Ginzburg-Landau equations of superconductivity.

    SciTech Connect

    Kaper, H. G.; Takac, P.; Mathematics and Computer Science; Univ. Rostock

    1997-01-01

    Gauge invariance is used to establish an equivalence relation between solutions of the time-independent and time-dependent Ginzburg-Landau equations that describe the same physical state of a superconductor. The equivalence relation shows how equilibrium configurations are obtained as large-time asymptotic limits of solutions of the time-dependent Ginzburg-Landau equations.

  9. Random attractors for the stochastic coupled fractional Ginzburg-Landau equation with additive noise

    SciTech Connect

    Shu, Ji E-mail: 530282863@qq.com; Li, Ping E-mail: 530282863@qq.com; Zhang, Jia; Liao, Ou

    2015-10-15

    This paper is concerned with the stochastic coupled fractional Ginzburg-Landau equation with additive noise. We first transform the stochastic coupled fractional Ginzburg-Landau equation into random equations whose solutions generate a random dynamical system. Then we prove the existence of random attractor for random dynamical system.

  10. Landau-Zener transition in quadratic nonlinear two-state systems

    SciTech Connect

    Ishkhanyan, A. M.

    2010-05-15

    A comprehensive theory of the Landau-Zener transition in quadratic nonlinear two-state systems is developed. A compact analytic formula involving elementary functions only is derived for the final transition probability. The formula provides a highly accurate approximation for the whole rage of the variation of the Landau-Zener parameter.

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

    SciTech Connect

    Yan Yue; Wu Biao

    2010-02-15

    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.

  12. Die Zeitung der Zukunft

    NASA Astrophysics Data System (ADS)

    Wieser, Christoph; Schaffert, Sebastian

    Schon lange wird spekuliert, wie wir in Zukunft Zeitung lesen werden. Werden wir am Frühstückstisch wie gewohnt in einer Zeitung aus Papier schmökern oder werden wir die Zeitung als biegsame Folie beschrieben mit elektronischer Tinte in Händen halten? Wird die Zeitung mit anderen Medien wie Radio und Fernsehen verschmelzen? Viele Varianten sind denkbar. Heute lässt sich schon ein Trend ablesen: Immer mehr Leser entdecken die Online-Zeitung als Informationsmedium, eine Voraussetzung für die Nutzung neuer Technologien in der Zeitung der Zukunft. In diesem Kapitel stellen wir Entwicklungsmöglichkeiten der Online-Zeitung dar, wie sie im Social Semantic Web möglich werden.

  13. Nonlinear electron acceleration by oblique whistler waves: Landau resonance vs. cyclotron resonance

    SciTech Connect

    Artemyev, A. V.; Agapitov, O. V.; Krasnoselskikh, V. V.; Mourenas, D.

    2013-12-15

    This paper is devoted to the study of the nonlinear interaction of relativistic electrons and high amplitude strongly oblique whistler waves in the Earth's radiation belts. We consider electron trapping into Landau and fundamental cyclotron resonances in a simplified model of dipolar magnetic field. Trapping into the Landau resonance corresponds to a decrease of electron equatorial pitch-angles, while trapping into the first cyclotron resonance increases electron equatorial pitch-angles. For 100 keV electrons, the energy gained due to trapping is similar for both resonances. For electrons with smaller energy, acceleration is more effective when considering the Landau resonance. Moreover, trapping into the Landau resonance is accessible for a wider range of initial pitch-angles and initial energies in comparison with the fundamental resonance. Thus, we can conclude that for intense and strongly oblique waves propagating in the quasi-electrostatic mode, the Landau resonance is generally more important than the fundamental one.

  14. Nanoscopy of Surface-Induced van der Waals-Zeeman Transitions

    SciTech Connect

    Hamamda, M.; Grucker, J.; Dutier, G.; Perales, F.; Baudon, J.; Ducloy, M.; Bocvarski, V.

    2008-10-22

    van der Waals transitions among magnetic sub-levels of a metastable rare gas atom passing near a surface immersed in a magnetic field, are described. Related transition amplitudes are calculated using both the sudden and the Landau-Zener approximations. Experimental data for Ne*({sup 3}P{sub 2}) atoms traversing a copper grating are presented. For a pair of surfaces (e.g. the opposite edges of a slit) and a sufficiently large coherence width, Fresnel's biprism interference fringes are obtained. From this interference pattern, detailed information about the transition amplitude at a sub-nanometric scale can be derived. The effect of gravity on this pattern is examined.

  15. Pressure in the Landau-Ginzburg functional: Pascal's law, nucleation in fluid mixtures, a meanfield theory of amphiphilic action, and interface wetting in glassy liquids

    NASA Astrophysics Data System (ADS)

    Chan, Ho Yin; Lubchenko, Vassiliy

    2015-09-01

    We set up the problem of finding the transition state for phase nucleation in multi-component fluid mixtures, within the Landau-Ginzburg density functional. We establish an expression for the coordinate-dependent local pressure that applies to mixtures, arbitrary geometries, and certain non-equilibrium configurations. The expression allows one to explicitly evaluate the pressure in spherical geometry, à la van der Waals. Pascal's law is recovered within the Landau-Ginzburg density functional theory, formally analogously to how conservation of energy is recovered in the Lagrangian formulation of mechanics. We establish proper boundary conditions for certain singular functional forms of the bulk free energy density that allow one to obtain droplet solutions with thick walls in essentially closed form. The hydrodynamic modes responsible for mixing near the interface are explicitly identified in the treatment; the composition at the interface is found to depend only weakly on the droplet size. Next we develop a Landau-Ginzburg treatment of the effects of amphiphiles on the surface tension; the amphiphilic action is seen as a violation of Pascal's law. We explicitly obtain the binding potential for the detergent at the interface and the dependence of the down-renormalization of the surface tension on the activity of the detergent. Finally, we argue that the renormalization of the activation barrier for escape from long-lived structures in glassy liquids can be viewed as an action of uniformly seeded, randomly oriented amphiphilic molecules on the interface separating two dissimilar aperiodic structures. This renormalization is also considered as a "wetting" of the interface. The resulting conclusions are consistent with the random first order transition theory.

  16. Pressure in the Landau-Ginzburg functional: Pascal's law, nucleation in fluid mixtures, a meanfield theory of amphiphilic action, and interface wetting in glassy liquids.

    PubMed

    Chan, Ho Yin; Lubchenko, Vassiliy

    2015-09-28

    We set up the problem of finding the transition state for phase nucleation in multi-component fluid mixtures, within the Landau-Ginzburg density functional. We establish an expression for the coordinate-dependent local pressure that applies to mixtures, arbitrary geometries, and certain non-equilibrium configurations. The expression allows one to explicitly evaluate the pressure in spherical geometry, à la van der Waals. Pascal's law is recovered within the Landau-Ginzburg density functional theory, formally analogously to how conservation of energy is recovered in the Lagrangian formulation of mechanics. We establish proper boundary conditions for certain singular functional forms of the bulk free energy density that allow one to obtain droplet solutions with thick walls in essentially closed form. The hydrodynamic modes responsible for mixing near the interface are explicitly identified in the treatment; the composition at the interface is found to depend only weakly on the droplet size. Next we develop a Landau-Ginzburg treatment of the effects of amphiphiles on the surface tension; the amphiphilic action is seen as a violation of Pascal's law. We explicitly obtain the binding potential for the detergent at the interface and the dependence of the down-renormalization of the surface tension on the activity of the detergent. Finally, we argue that the renormalization of the activation barrier for escape from long-lived structures in glassy liquids can be viewed as an action of uniformly seeded, randomly oriented amphiphilic molecules on the interface separating two dissimilar aperiodic structures. This renormalization is also considered as a "wetting" of the interface. The resulting conclusions are consistent with the random first order transition theory. PMID:26429019

  17. Zum Stellenwert der Unterdruck-Instillationstherapie in der Dermatologie.

    PubMed

    Müller, Cornelia Sigrid Lissi; Burgard, Barbara; Zimmerman, Monika; Vogt, Thomas; Pföhler, Claudia

    2016-08-01

    Die Methoden zur Behandlung akuter und chronischer Wunden unterliegen einer steten Weiterentwicklung, Reevaluierung und Anwendung innovativer Therapieformen. Die Vakuumtherapie zur Wundbehandlung gehört zu den etablierten Behandlungsmodalitäten. Ein innovatives Verfahren kombiniert die Vakuumtherapie mit der automatisierten, kontrollierten Zufuhr und Drainage wirkstoffhaltiger Lösungen zur topischen Wundbehandlung im Wundbett und auch wirkstofffrei durch Instillation physiologischer Kochsalzlösung (Unterdruck-Instillationstherapie). Hierdurch können die Effekte der konventionellen Vakuumtherapie mit denen der lokalen Antisepsis kombiniert werden. Hierdurch kommt es zu einer Reduktion der Wundfläche, einer Induktion von Granulationsgewebe sowie einer Reduktion der Keimbesiedelung der Wunden. Bisher publizierte Studien konzentrieren sich auf die Anwendung dieses Therapieverfahrens zur Behandlung orthopädisch-chirurgischer Krankheiten. Die Datenlage bezüglich der Vakuum-Instillationstherapie in der Dermatochirurgie beschränkt sich derzeit auf Fallberichte und Einzelfallerfahrungen. Randomisierte, prospektive Studien zum Vergleich der Vakuum-Instillationstherapie zur Behandlung dermatologischer Krankheitsbilder existieren bislang nicht. Ziele des vorliegenden Artikels sind die Vorstellung der Vakuumtherapie mit Instillation einschließlich ihres Wirkprinzips, deren mögliche Komplikationen, die Diskussion erdenklicher Kontraindikationen sowie eine Übersicht über die aktuell verfügbare Datenlage. Zusammenfassend scheint sich die Evidenz zu verdichten, dass mittels Unterdruck-Instillationstherapie sowohl einfache als auch komplizierte Wunden effizient behandelt werden können, was sich in einer deutlichen Beschleunigung der Wundgranulation mit konsekutiv früher möglichem Defektverschluss äußert. PMID:27509413

  18. Landau-Zener Bloch Oscillations with Perturbed Flat Bands

    NASA Astrophysics Data System (ADS)

    Khomeriki, Ramaz; Flach, Sergej

    2016-06-01

    Sinusoidal Bloch oscillations appear in band structures exposed to external fields. Landau-Zener (LZ) tunneling between different bands is usually a counteracting effect limiting Bloch oscillations. Here we consider a flat band network with two dispersive and one flat band, e.g., for ultracold atoms and optical waveguide networks. Using external synthetic gauge and gravitational fields we obtain a perturbed yet gapless band structure with almost flat parts. The resulting Bloch oscillations consist of two parts—a fast scan through the nonflat part of the dispersion structure, and an almost complete halt for substantial time when the atomic or photonic wave packet is trapped in the original flat band part of the unperturbed spectrum, made possible due to LZ tunneling.

  19. Landau-Zener Bloch Oscillations with Perturbed Flat Bands.

    PubMed

    Khomeriki, Ramaz; Flach, Sergej

    2016-06-17

    Sinusoidal Bloch oscillations appear in band structures exposed to external fields. Landau-Zener (LZ) tunneling between different bands is usually a counteracting effect limiting Bloch oscillations. Here we consider a flat band network with two dispersive and one flat band, e.g., for ultracold atoms and optical waveguide networks. Using external synthetic gauge and gravitational fields we obtain a perturbed yet gapless band structure with almost flat parts. The resulting Bloch oscillations consist of two parts-a fast scan through the nonflat part of the dispersion structure, and an almost complete halt for substantial time when the atomic or photonic wave packet is trapped in the original flat band part of the unperturbed spectrum, made possible due to LZ tunneling. PMID:27367392

  20. Multiple Walkers in the Wang-Landau Algorithm

    SciTech Connect

    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.

  1. Generalized Landau Lifshitz Gilbert equation for uniformly magnetized bodies

    NASA Astrophysics Data System (ADS)

    Serpico, C.; Mayergoyz, I. D.; Bertotti, G.; d'Aquino, M.; Bonin, R.

    2008-02-01

    We consider generalized Landau-Lifshitz-Gilbert (LLG) deterministic dynamics in uniformly magnetized bodies. The dynamics take place on the unit sphere Σ, and are characterized by a vector field v tangential to Σ. By using Helmholtz decomposition on Σ, it is proven that v is uniquely defined by two potentials χ and ψ. Potential χ can be identified with the free energy of the system, while ψ describes non-conservative interactions of the system with the environment. The presence of ψ 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.

  2. Stochastic Landau-Lifshitz-Gilbert Equation with Delayed Feedback Field

    NASA Astrophysics Data System (ADS)

    Tutu, H.; Horita, T.

    2008-08-01

    A time-delayed feedback control to stabilize a swinging motion of magnetic moment in a single-domain magnetic system under AC field is studied. The system has a uniaxial anisotropy, and the AC field is parallel to this. Without control, it prefers the Ising state that is (anti)parallel to the anisotropy axis. The control stabilizes the oscillation across the equatorial plane perpendicular to the anisotropy axis (swinging motion). Employing a stochastic Landau-Lifshitz-Gilbert (LLG) equation, we study the effects of thermal fluctuation on the controlled state. Linear fluctuation, in which variance linearly depends on noise intensity, around the controlled state is analyzed in terms of correlation function and spectral density, and a criterion for the existence of such a linear relationship is obtained. Several technical improvements in the treatment of the stochastic LLG equation and the corresponding Fokker-Planck equation with stereographic coordinate system are also show n.

  3. Landau damping of Langmuir twisted waves with kappa distributed electrons

    SciTech Connect

    Arshad, Kashif Aman-ur-Rehman; Mahmood, Shahzad

    2015-11-15

    The kinetic theory of Landau damping of Langmuir twisted modes is investigated in the presence of orbital angular momentum of the helical (twisted) electric field in plasmas with kappa distributed electrons. The perturbed distribution function and helical electric field are considered to be decomposed by Laguerre-Gaussian mode function defined in cylindrical geometry. The Vlasov-Poisson equation is obtained and solved analytically to obtain the weak damping rates of the Langmuir twisted waves in a nonthermal plasma. The strong damping effects of the Langmuir twisted waves at wavelengths approaching Debye length are also obtained by using an exact numerical method and are illustrated graphically. The damping rates of the planar Langmuir waves are found to be larger than the twisted Langmuir waves in plasmas which shows opposite behavior as depicted in Fig. 3 by J. T. Mendoça [Phys. Plasmas 19, 112113 (2012)].

  4. Landau damping of Langmuir twisted waves with kappa distributed electrons

    NASA Astrophysics Data System (ADS)

    Arshad, Kashif; Aman-ur-Rehman, Mahmood, Shahzad

    2015-11-01

    The kinetic theory of Landau damping of Langmuir twisted modes is investigated in the presence of orbital angular momentum of the helical (twisted) electric field in plasmas with kappa distributed electrons. The perturbed distribution function and helical electric field are considered to be decomposed by Laguerre-Gaussian mode function defined in cylindrical geometry. The Vlasov-Poisson equation is obtained and solved analytically to obtain the weak damping rates of the Langmuir twisted waves in a nonthermal plasma. The strong damping effects of the Langmuir twisted waves at wavelengths approaching Debye length are also obtained by using an exact numerical method and are illustrated graphically. The damping rates of the planar Langmuir waves are found to be larger than the twisted Langmuir waves in plasmas which shows opposite behavior as depicted in Fig. 3 by J. T. Mendoça [Phys. Plasmas 19, 112113 (2012)].

  5. Wang-Landau simulation of Gō model molecules.

    PubMed

    Böker, Arne; Paul, Wolfgang

    2016-01-01

    Gō-like models are one of the oldest protein modeling concepts in computational physics and have proven their value over and over for forty years. The essence of a Gō model is to define a native contact matrix for a well-defined low-energy polymer configuration, e.g., the native state in the case of proteins or peptides. Many different potential shapes and many different cut-off distances in the definition of this native contact matrix have been proposed and applied. We investigate here the physical consequences of the choice for this cut-off distance in the Gō models derived for a square-well tangent sphere homopolymer chain. For this purpose we are performing flat-histogram Monte Carlo simulations of Wang-Landau type, obtaining the thermodynamic and structural properties of such models over the complete temperature range. Differences and similarities with Gō models for proteins and peptides are discussed. PMID:26810395

  6. Dynamics of the Ginzburg-Landau equations of superconductivity

    SciTech Connect

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

    1997-08-01

    This article is concerned with the dynamical properties of solutions of the time-dependent Ginzburg-Landau (TDGL) equations of superconductivity. It is shown that the TDGL equations define a dynamical process when the applied magnetic field varies with time, and a dynamical system when the applied magnetic field is stationary. The dynamical system describes the large-time asymptotic behavior: Every solution of the TDGL equations is attracted to a set of stationary solutions, which are divergence free. These results are obtained in the {open_quotes}{phi} = -{omega}({gradient}{center_dot}A){close_quotes} gauge, which reduces to the standard {close_quotes}{phi} = -{gradient}{center_dot}A{close_quotes} gauge if {omega} = 1 and to the zero-electric potential gauge if {omega} = 0; the treatment captures both in a unified framework. This gauge forces the London gauge, {gradient}{center_dot}A = 0, for any stationary solution of the TDGL equations.

  7. [A special case of 'deafness'; Landau-Kleffner syndrome].

    PubMed

    Stroink, H; Van Dongen, H R; Meulstee, J; Scheltens-de Boer, M; Geesink, H H

    1997-08-16

    A boy aged 5 had displayed from the age of 3 a fluctuating deficit in understanding spoken language. Audiometric testing proved his hearing to be normal. After 18 months, the parents noticed minor attacks of 'absence'. An EEG showed a normal background pattern and frequent spikes and spike waves complexes; CT-scanning of the brain revealed no abnormalities. On the basis of the acquired language disorder, the seizures and the features of the nocturnal EEG, the diagnosis the syndrome of Landau-Kleffner was made. After treatment with ethosuximide a temporary improvement of the aphasia occurred. A permanent improvement however was realized by treatment with prednisone. The boy could attend a primary school. The syndrome runs a fluctuating course; the patient may recover, but he may also undergo general mental deterioration. Antiepileptic agents only may have a brief favorable effect on the aphasia. In case of failure corticosteroids or even subpial cortical transsection are indicated. PMID:9543768

  8. Improving Wang-Landau sampling with adaptive windows

    NASA Astrophysics Data System (ADS)

    Cunha-Netto, A. G.; Caparica, A. A.; Tsai, Shan-Ho; Dickman, Ronald; Landau, D. P.

    2008-11-01

    Wang-Landau sampling (WLS) of large systems requires dividing the energy range into “windows” and joining the results of simulations in each window. The resulting density of states (and associated thermodynamic functions) is shown to suffer from boundary effects in simulations of lattice polymers and the five-state Potts model. Here, we implement WLS using adaptive windows. Instead of defining fixed energy windows (or windows in the energy-magnetization plane for the Potts model), the boundary positions depend on the set of energy values on which the histogram is flat at a given stage of the simulation. Shifting the windows each time the modification factor f is reduced, we eliminate border effects that arise in simulations using fixed windows. Adaptive windows extend significantly the range of system sizes that may be studied reliably using WLS.

  9. Longitudinal hydrodynamics from event-by-event Landau initial conditions

    SciTech Connect

    Sen, Abhisek; Gerhard, Jochen; Torrieri, Giorgio; Read, Kenneth; Wong, Cheuk-Yin

    2015-02-02

    Here we investigate three-dimensional ideal hydrodynamic evolution, with Landau initial conditions, incorporating event-by-event variation with many events and transverse density inhomogeneities. We show that the transition to boost-invariant flow occurs too late for realistic setups, with corrections of θ (20%-30%) expected at freeze-out for most scenarios. Moreover, the deviation from boost invariance is correlated with both transverse flow and elliptic flow, with the more highly transversely flowing regions also showing the most violation of boost invariance. Therefore, if longitudinal flow is not fully developed at the early stages of heavy ion collisions, hydrodynamics where boost invariance holds at midrapidity is inadequate to extract transport coefficients of the quark-gluon plasma. We conclude by arguing that developing experimental probes of boost invariance is necessary, and suggest some promising directions in this regard.

  10. Longitudinal hydrodynamics from event-by-event Landau initial conditions

    DOE PAGESBeta

    Sen, Abhisek; Gerhard, Jochen; Torrieri, Giorgio; Read, Kenneth; Wong, Cheuk-Yin

    2015-02-02

    Here we investigate three-dimensional ideal hydrodynamic evolution, with Landau initial conditions, incorporating event-by-event variation with many events and transverse density inhomogeneities. We show that the transition to boost-invariant flow occurs too late for realistic setups, with corrections of θ (20%-30%) expected at freeze-out for most scenarios. Moreover, the deviation from boost invariance is correlated with both transverse flow and elliptic flow, with the more highly transversely flowing regions also showing the most violation of boost invariance. Therefore, if longitudinal flow is not fully developed at the early stages of heavy ion collisions, hydrodynamics where boost invariance holds at midrapidity ismore » inadequate to extract transport coefficients of the quark-gluon plasma. We conclude by arguing that developing experimental probes of boost invariance is necessary, and suggest some promising directions in this regard.« less

  11. Second-quantized Landau-Zener theory for dynamical instabilities

    SciTech Connect

    Anglin, J.R.

    2003-05-01

    State engineering in nonlinear quantum dynamics sometimes may demand driving the system through a sequence of dynamically unstable intermediate states. This very general scenario is especially relevant to the dilute Bose-Einstein condensates, for which ambitious control schemes have been based on the powerful Gross-Pitaevskii mean-field theory. Since this theory breaks down on logarithmically short time scales in the presence of dynamical instabilities, an interval of instabilities introduces quantum corrections, which may possibly derail a control scheme. To provide a widely applicable theory for such quantum corrections, this paper solves a general problem of time-dependent quantum-mechanical dynamical instability, by modeling it as a second-quantized analog of a Landau-Zener avoided crossing: a 'twisted crossing'.

  12. Spin-transistor action via tunable Landau-Zener transitions.

    PubMed

    Betthausen, C; Dollinger, T; Saarikoski, H; Kolkovsky, V; Karczewski, G; Wojtowicz, T; Richter, K; Weiss, D

    2012-07-20

    Spin-transistor designs relying on spin-orbit interaction suffer from low signal levels resulting from low spin-injection efficiency and fast spin decay. Here, we present an alternative approach in which spin information is protected by propagating this information adiabatically. We demonstrate the validity of our approach in a cadmium manganese telluride diluted magnetic semiconductor quantum well structure in which efficient spin transport is observed over device distances of 50 micrometers. The device is turned "off" by introducing diabatic Landau-Zener transitions that lead to a backscattering of spins, which are controlled by a combination of a helical and a homogeneous magnetic field. In contrast to other spin-transistor designs, we find that our concept is tolerant against disorder. PMID:22822145

  13. Landau-Khalatnikov-Fradkin transformations in reduced quantum electrodynamics

    NASA Astrophysics Data System (ADS)

    Ahmad, A.; Cobos-Martínez, J. J.; Concha-Sánchez, Y.; Raya, A.

    2016-05-01

    We derive the Landau-Khalatnikov-Frandkin transformation (LKFT) for the fermion propagator in quantum electrodynamics (QED) described within a brane-world inspired framework where photons are allowed to move in dγ space-time (bulk) dimensions, while electrons remain confined to a de -dimensional brane, with de

  14. Topological Entanglement Entropy in the Second Landau Level

    NASA Astrophysics Data System (ADS)

    Friedman, B. A.; Levine, G. C.

    The entanglement entropy of the incompressible states of a realistic quantum Hall system in the second Landau level is studied by direct diagonalization. The subdominant term of the area law, the topological entanglement entropy, which is believed to carry information about topological order in the ground state, was extracted for filling factors ν = 12/5 and ν = 7/3. While it is difficult to make strong conclusions about ν = 12/5, the ν = 7/3 state appears to be very consistent with the topological entanglement entropy for the k = 4 Read-Rezayi state. The effect of finite thickness corrections to the Coulomb potential used in the direct diagonalization is also systematically studied.

  15. Thermodynamics of RNA structures by Wang–Landau sampling

    PubMed Central

    Lou, Feng; Clote, Peter

    2010-01-01

    Motivation: Thermodynamics-based dynamic programming RNA secondary structure algorithms have been of immense importance in molecular biology, where applications range from the detection of novel selenoproteins using expressed sequence tag (EST) data, to the determination of microRNA genes and their targets. Dynamic programming algorithms have been developed to compute the minimum free energy secondary structure and partition function of a given RNA sequence, the minimum free-energy and partition function for the hybridization of two RNA molecules, etc. However, the applicability of dynamic programming methods depends on disallowing certain types of interactions (pseudoknots, zig-zags, etc.), as their inclusion renders structure prediction an nondeterministic polynomial time (NP)-complete problem. Nevertheless, such interactions have been observed in X-ray structures. Results: A non-Boltzmannian Monte Carlo algorithm was designed by Wang and Landau to estimate the density of states for complex systems, such as the Ising model, that exhibit a phase transition. In this article, we apply the Wang-Landau (WL) method to compute the density of states for secondary structures of a given RNA sequence, and for hybridizations of two RNA sequences. Our method is shown to be much faster than existent software, such as RNAsubopt. From density of states, we compute the partition function over all secondary structures and over all pseudoknot-free hybridizations. The advantage of the WL method is that by adding a function to evaluate the free energy of arbitary pseudoknotted structures and of arbitrary hybridizations, we can estimate thermodynamic parameters for situations known to be NP-complete. This extension to pseudoknots will be made in the sequel to this article; in contrast, the current article describes the WL algorithm applied to pseudoknot-free secondary structures and hybridizations. Availability: The WL RNA hybridization web server is under construction at http

  16. Van der Waals Forces

    NASA Astrophysics Data System (ADS)

    Parsegian, V. Adrian

    2006-03-01

    This should prove to be the definitive work explaining van der Waals forces, how to calculate them and take account of their impact under any circumstances and conditions. These weak intermolecular forces are of truly pervasive impact, and biologists, chemists, physicists and engineers will profit greatly from the thorough grounding in these fundamental forces that this book offers. Parsegian has organized his book at three successive levels of mathematical sophistication, to satisfy the needs and interests of readers at all levels of preparation. The Prelude and Level 1 are intended to give everyone an overview in words and pictures of the modern theory of van der Waals forces. Level 2 gives the formulae and a wide range of algorithms to let readers compute the van der Waals forces under virtually any physical or physiological conditions. Level 3 offers a rigorous basic formulation of the theory. Author is among the most highly respected biophysicists Van der Waals forces are significant for a wide range of questions and problems in the life sciences, chemistry, physics, and engineering, ranging up to the macro level No other book that develops the subject vigorously, and this book also makes the subject intuitively accessible to students who had not previously been mathematically sophisticated enough to calculate them

  17. Das mechatronische Fahrwerk der Zukunft

    NASA Astrophysics Data System (ADS)

    Rieth, Peter

    Technologiesprünge gab es immer wieder in der Geschichte der Automobiltechnologie, so auch in der Kraftfahrzeugbremse, die seit ihren Anfängen eine stete Weiterentwicklung erfahren hat (Bild 40-1). So erlangten schon mechanische Bremsen durchaus ein hohes Niveau, ehe die Hydraulik Mitte der zwanziger Jahre für Komfort und Sicherheit vollkommen neue Perspektiven eröffnete, welche durch Einführung der Hilfskraft(servo)bremsanlagen Mitte des letzten Jahrhunderts noch erweitert wurden. Den wichtigsten Technologiesprung, den der Kunde als Fortschritt erkennt und dementsprechend honoriert, ermöglichte die Elektronik Mitte der siebziger Jahre. ABS, ASR, EBV und nicht zuletzt ESC wären ohne sie nicht vorstellbar.

  18. Demonstration of Geometric Landau-Zener Interferometry in a Superconducting Qubit

    NASA Astrophysics Data System (ADS)

    Tan, Xinsheng; Zhang, Dan-Wei; Zhang, Zhentao; Yu, Yang; Han, Siyuan; Zhu, Shi-Liang

    2014-01-01

    Geometric quantum manipulation and Landau-Zener interferometry have been separately explored in many quantum systems. In this Letter, we combine these two approaches to study the dynamics of a superconducting phase qubit. We experimentally demonstrate Landau-Zener interferometry based on the pure geometric phases in this solid-state qubit. We observe the interference caused by a pure geometric phase accumulated in the evolution between two consecutive Landau-Zener transitions, while the dynamical phase is canceled out by a spin-echo pulse. The full controllability of the qubit state as a function of the intrinsically robust geometric phase provides a promising approach for quantum state manipulation.

  19. Reorientation of quantum Hall stripes within a partially filled Landau level

    NASA Astrophysics Data System (ADS)

    Shi, Q.; Zudov, M. A.; Watson, J. D.; Gardner, G. C.; Manfra, M. J.

    We investigate the effect of the filling factor on transport anisotropies, known as stripes, in high Landau levels of a two-dimensional electron gas. We find that at certain in-plane magnetic fields, the stripes orientation is sensitive to the filling factor within a given Landau level. This sensitivity gives rise to the emergence of stripes away from half-filling while orthogonally-oriented, native stripes reside at half-filling. We attribute this switching of the anisotropy axes within a single Landau level to a strong dependence of the native symmetry breaking potential on the filling factor.

  20. Reorientation of quantum Hall stripes within a partially filled Landau level

    NASA Astrophysics Data System (ADS)

    Shi, Q.; Zudov, M. A.; Watson, J. D.; Gardner, G. C.; Manfra, M. J.

    2016-03-01

    We investigate the effect of the filling factor on transport anisotropies, known as stripes, in high Landau levels of a two-dimensional electron gas. We find that at certain in-plane magnetic fields, the stripes orientation is sensitive to the filling factor within a given Landau level. This sensitivity gives rise to the emergence of stripes away from half-filling while orthogonally oriented, native stripes reside at half-filling. This switching of the anisotropy axes within a single Landau level can be attributed to a strong dependence of the native symmetry-breaking potential on the filling factor.

  1. Landau damping of the weak head-tail instability at Tevatron

    SciTech Connect

    Ivanov, P.M.; Alexahin, Y.; Annala, J.; Lebedev, V.A.; Shiltsev, V.; /Fermilab

    2005-05-01

    Two-step improvement of transverse beam stability has been done at the Tevatron. First, shielding of the laminated Lambertson magnets significantly reduced the transverse impedance. Second, Landau damping induced by the octupoles allowed machine operation with zero chromaticity at injection. That has resulted in a dynamic aperture increase and weakening of long-range beam-beam effects due to smaller chromatic tune modulation. At collisions, the coherent tunes and incoherent tune continuum are separated due to the head-on collisions. That leads to Landau damping loss at small chromaticities. Predictions of the analytical Landau damping model are compared with experiments.

  2. Landau damping in space plasmas with generalized (r,q) distribution function

    SciTech Connect

    Qureshi, M.N.S.; Shi, J.K.; Ma, S.Z.

    2005-12-15

    Space plasmas possessing non-Maxwellian particle distribution functions with an enhanced high-energy tail and shoulder in the profile of distribution function take an important role to the wave particle interaction. In the present paper Landau damping of electron plasma (Langmuir) waves and ion-acoustic waves in a hot, isotropic, unmagnetized plasma is studied with the generalized (r,q) distribution function. The results show that for the Langmuir oscillations Landau damping becomes severe as the spectral index r or q reduces. However, for the ion-acoustic waves Landau damping is more sensitive to the ion temperature than the spectral indices.

  3. Demonstration of geometric Landau-Zener interferometry in a superconducting qubit.

    PubMed

    Tan, Xinsheng; Zhang, Dan-Wei; Zhang, Zhentao; Yu, Yang; Han, Siyuan; Zhu, Shi-Liang

    2014-01-17

    Geometric quantum manipulation and Landau-Zener interferometry have been separately explored in many quantum systems. In this Letter, we combine these two approaches to study the dynamics of a superconducting phase qubit. We experimentally demonstrate Landau-Zener interferometry based on the pure geometric phases in this solid-state qubit. We observe the interference caused by a pure geometric phase accumulated in the evolution between two consecutive Landau-Zener transitions, while the dynamical phase is canceled out by a spin-echo pulse. The full controllability of the qubit state as a function of the intrinsically robust geometric phase provides a promising approach for quantum state manipulation. PMID:24484040

  4. Gauging a Quantum Heat Bath with Dissipative Landau-Zener Transitions

    SciTech Connect

    Wubs, Martijn; Kohler, Sigmund; Haenggi, Peter; Saito, Keiji; Kayanuma, Yosuke

    2006-11-17

    We calculate the exact Landau-Zener transition probabilities for a qubit with an arbitrary linear coupling to a bath at zero temperature. The final quantum state exhibits a peculiar entanglement between the qubit and the bath. In the special case of diagonal coupling, the bath does not influence the transition probability, whatever the speed of the Landau-Zener sweep. It is proposed to use Landau-Zener transitions to determine both the reorganization energy and the integrated spectral density of the bath. Possible applications include circuit QED and molecular nanomagnets.

  5. Multi-particle and multi-state Landau-Zener model: Dynamic matrix approach

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    The paper presents the multi-particle and multi-state Landau-Zener problem and focuses on indistinguishable particles with degenerate states applying the Dynamics matrix approach. It is observed that the probabilities are described by the Binomial law with the limiting values that achieved exact results for spin and Landau-Zener problems. The derivation of the generalized multi-particle probability function is observed to be equivalent to solving a Landau-Zener problem for particle number equal to twice the spin.

  6. Evaluation der zentralen TUM-Lernplattform

    NASA Astrophysics Data System (ADS)

    Schulze, Elvira; Baume, Matthias; Graf, Stephan; Gergintchev, Ivan

    Die Notwendigkeit der Qualitätssicherung und -kontrolle für innovative universitäre Lehr-/Lernszenarien ist in der Praxis unbestritten. Die Wirksamkeit der Einführung der zentralen Lernplattform CLIX Campus der imc AG an der TUM wurde mittels quantitativer und qualitativer Evaluation überprüft. Als statistische Bewertungsgrundlage wurde der Erreichungsgrad bestimmter Projektziele herangezogen. Aufbauend auf den theoretischen Grundlagen der Evaluation von Bildungsangeboten gibt diese Studie Aufschluss über die Ergebnisse der Datenerhebungen sowie die Einschätzung der Plattform aus Nutzersicht und belegt die wesentliche Bedeutung der durchgängigen IT-Infrastruktur und speziell der einheitlichen Verfügbarkeit der eLearning Angebote.

  7. Haftung in der Medizintechnik

    NASA Astrophysics Data System (ADS)

    Müller, Ute; Lücker, Volker

    Die Unversehrtheit von Leib und Leben ist das größte Rechtsgut unserer Gesellschaft. Dies macht schon das Grundgesetz in Art. 2 Abs. Satz 1 GG deutlich. Die Öffentlichkeit zeigt daher größtes Interesse an Produkten, welche der Gesundheit dienen und Leben retten oder erhalten. Dieses Interesse gilt einerseits der Entwicklung und Bereitstellung leistungsfähiger Medizinprodukte, andererseits zielt es auf deren Sicherheit. Um vor allem letztere zu gewährleisten, nimmt der Gesetzgeber alle Beteiligten in die Pflicht, die auftretenden Risiken auf das geringstmögliche Maß zu begrenzen. Dies spiegelt sich in den rechtlichen Vorgaben ebenso wie in den Haftungsfolgen, die bei Verletzung dieser Vorgaben greifen, wieder. Diese Folgen können dementsprechend gravierend ausfallen, von Geldstrafen bis zu Freiheitsstrafen, von Bußgeldzahlungen bis zum Schadenersatzansprüchen, die schnell ein wirtschaftliches Aus bedeuten können. Den Beteiligten, allen voran den Herstellern, muss deshalb daran gelegen sein, nicht nur die Produkte, sondern auch deren Sicherheit stetig weiter zu entwickeln.

  8. Landau retardation on the occurrence scattering time in quantum electron-hole plasmas

    NASA Astrophysics Data System (ADS)

    Hong, Woo-Pyo; Jung, Young-Dae

    2016-03-01

    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.

  9. Towards the continuum limit of the lattice Landau gauge gluon propagator

    SciTech Connect

    Oliveira, O.; Silva, P. J.

    2011-05-23

    The infrared behaviour of the lattice Landau gauge gluon propagator is discussed, combining results from simulations with different volumes and lattice spacings. In particular, the Cucchieri-Mendes bounds are computed and their implications for D(0) discussed.

  10. Anomalous coincidences between valley split Landau levels in a Si/SiGe heterostructure

    NASA Astrophysics Data System (ADS)

    Schumacher, H. W.; Nauen, A.; Zeitler, U.; Haug, R. J.; Weitz, P.; Jansen, A. G. M.; Schäffler, F.

    1998-12-01

    We have performed magneto-transport experiments on a high mobility 2DEG in a Si/SiGe heterojunction in tilted magnetic fields up to 26 T at temperatures down to 450 mK. When tilting the sample in the magnetic field the value of the spin splitting increases with respect to the Landau level splitting leading to an overlap of spin-split sub-levels of different Landau levels, the so-called coincidences. Coincidences between up to five neighbouring Landau levels are found. From their positions we deduce a Landé factor g ∗≈3.4 . Coincidences between the lowest Landau levels with fully resolved individual valley states show extremely high SdH peaks compared to the individual SdH maxima outside the coincidence suggesting strong exchange enhancement effects in the occurrence of the coincidence.

  11. REDUCTION OF COMPRESSIBILITY AND PARALLEL TRANSFER BY LANDAU DAMPING IN TURBULENT MAGNETIZED PLASMAS

    SciTech Connect

    Hunana, P.; Laveder, D.; Passot, T.; Sulem, P. L.; Borgogno, D.

    2011-12-20

    Three-dimensional numerical simulations of decaying turbulence in a magnetized plasma are performed using a so-called finite Larmor radius (FLR)-Landau fluid model which incorporates linear Landau damping and FLR corrections. It is shown that compared to simulations of compressible Hall-MHD, linear Landau damping is responsible for significant damping of magnetosonic waves, which is consistent with the linear kinetic theory. Compressibility of the fluid and parallel energy cascade along the ambient magnetic field are also significantly inhibited when the beta parameter is not too small. In contrast with Hall-MHD, the FLR-Landau fluid model can therefore correctly describe turbulence in collisionless plasmas such as solar wind, providing an interpretation for its nearly incompressible behavior.

  12. Combined topological and Landau order from strong correlations in Chern bands

    NASA Astrophysics Data System (ADS)

    Daghofer, Maria; Kourtis, Stefanos

    2014-03-01

    In recent years, topologically nontrivial and nearly dispersionless bands have attracted attention as hosts for states analogous to fractional quantum-Hall states, but without a magnetic field. Indeed, such fractional Chern insulators were found and connections to fractional quantum-Hall states in Landau levels were established. We discuss here aspects where fractional Chern insulators differ from Landau levels. In particular, we present a class of states where both topological order and symmetry breaking arise spontaneously: the states show both fractional Hall conductivity and charge order. This coexistence of topological and conventional Landau order relies on the geometric frustration of the underlying lattice and consequently goes qualitatively beyond physics found in continuous Landau levels with their weak lattice. Supported by the Emmy-Noether program of the Deutsche Forschungsgemeinschaft (DFG).

  13. Nonlinear wave-particle resonant interaction in the radiation belts: Landau resonance vs. fundamental cyclotron resonance

    NASA Astrophysics Data System (ADS)

    Krasnoselskikh, V.; Artemyev, A.; Agapitov, O. V.; Mourenas, D.

    2013-12-01

    We present selected THEMIS observations of highly-oblique and large amplitude chorus waves at medium latitudes. The major part of observed waves propagates at nearly-electrostatic mode with normal angles close to resonance cone. We use test particle simulations and analytical theory to estimate efficiency of nonlinear particle acceleration by these waves via Landau and fundamental cyclotron resonances. We show that trapping into the Landau resonance corresponds to a decrease of electron equatorial pitch-angles, while trapping into the first cyclotron resonance increases electron equatorial pitch-angles. For 100 keV electrons, the energy gain is larger for the trapping due to Landau resonance. Moreover, trapping into the Landau resonance is accessible for a wider range of initial pitch-angles in comparison with the fundamental resonance.

  14. Ginzburg-Landau theory of a trapped Fermi gas with a BEC-BCS crossover

    SciTech Connect

    Huang Kun; Yu Zengqiang; Yin Lan

    2009-05-15

    The Ginzburg-Landau theory of a trapped Fermi gas with a BEC-BCS crossover is derived by the path-integral method. In addition to the standard Ginzburg-Landau equation, a second equation describing the total atom density is obtained. These two coupled equations are necessary to describe both homogeneous and inhomogeneous systems. The Ginzburg-Landau theory is valid near the transition temperature T{sub c} on both sides of the crossover. In the weakly interacting BEC region, it is also accurate at zero temperature where the Ginzburg-Landau equation can be mapped onto the Gross-Pitaevskii (GP) equation. The applicability of GP equation at finite temperature is discussed. On the BEC side, the fluctuation of the order parameter is studied and the renormalization to the molecule coupling constant is obtained.

  15. Toward the Landau-Lifshitz version of the Thomson electrostatics theorem

    NASA Astrophysics Data System (ADS)

    Grinfeld, Michael; Grinfeld, Pavel

    In the classical textbook (Landau and Lifshitz, 1963), Landau and Lifshtz suggested their version of the famous Thomson variational principle (a.k.a Thomson theorem.) So far, their version has not gained the interest it deserves, either among physicists or among applied mathematicians. Partially, the lack of interest can be explained because of the quality of the suggested proof of the principle. It is considerably lower than the standards accepted in classical electrostatics and mathematical physics. Even more importantly, Landau and Lifshitz did not demostrate the minimum property of the electrostatic energy at equilibrium. In this note, we, first, modify and specify the Landau-Lifshitz formulation of the principle presenting it as the isoperimetric variational problem. Then, for this isoperimetric problem we calculate the first and second variations, and we prove that the first variation vanishes, whereas the second variation appears to be positive.

  16. Experimental evidence and the Landau-Zener promotion in nucleus-nucleus collisions

    SciTech Connect

    Cindro, N.; Freeman, R.M.; Haas, F.

    1986-04-01

    Recent data from C+O collisions are analyzed in terms of the Landau-Zener promotion in nuclei. Evidence for the presence of this mechanism in nuclear collisions is of considerable interest, since it provides a signature of single-particle orbitals in molecular-type potentials and, at the same time, paves the way to a microscopic understanding of the collision dynamics, in particular of the energy dissipation rate. The analyzed data are of two types: integrated cross sections and angular distributions of inelastically scattered particles. The first set of data shows structure qualitatively consistent with recent calculations of the Landau-Zener effect; for this set of data no other reasonable explanation is presently available. The second set of data, while consistent with the presence of the Landau-Zener promotion, is examined in terms of other possible explanations too. The combined data show evidence favoring the presence of the Landau-Zener promotion in nucleus-nucleus collisions.

  17. Der Forsch-Frosch Fred

    NASA Astrophysics Data System (ADS)

    Kaibel, Volker

    Bewegt man sich auf der Suche nach Informationen zu einem bestimmten Thema immer neuen Links folgend durch das World-Wide-Web, so stellt man in der Regel nach einer gewissen Zeit fest, dass man auf manchen Seiten immer wieder gelandet ist. Diese Seiten stellen sich oft als wichtig heraus. Suchmaschinen wie Google machen sich dieses Phänomen zu Nutze, um die Wichtigkeit einzelner Web-Seiten zu bewerten. Dazu lassen sie auf einer beliebigen Web-Seite einen imaginären Surfer starten, der immer zufällig einen der auf seiner aktuell besuchten Seite vorgefundenen Links verfolgt. Der Surfer vollführt einen Random Walk im Netzwerk der Web-Seiten.

  18. Description of a dissipative quantum spin dynamics with a Landau-Lifshitz/Gilbert like damping and complete derivation of the classical Landau-Lifshitz equation

    NASA Astrophysics Data System (ADS)

    Wieser, Robert

    2015-03-01

    The classical Landau-Lifshitz equation has been derived from quantum mechanics. Starting point is the assumption of a non-Hermitian Hamilton operator to take the energy dissipation into account. The corresponding quantum mechanical spin dynamics along with the time dependent Schrödinger, Liouville and Heisenberg equation has been described and the similarities and differences between classical and quantum mechanical spin dynamics have been discussed. Furthermore, a time dependent Schrödinger equation corresponding to the classical Landau-Lifshitz-Gilbert equation and two ways to include temperature into the quantum mechanical spin dynamics have been proposed.

  19. Rotationally symmetric solutions of the Landau-Lifshitz and diffusion equations

    SciTech Connect

    Mayergoyz, I. D.; Bertotti, G.; Serpico, C.

    2000-05-01

    The problem of isotropic conducting ferromagnetic film subject to in-plane circular polarized magnetic fields is discussed. This problem requires simultaneous solution of diffusion and Landau-Lifshitz equations. It is observed that the mathematical formulation of the problem is invariant with respect to rotations in the film plane. By exploiting this invariance, the rotationally symmetric solutions of the Landau-Lifshitz equation coupled with the diffusion equation are obtained and examined. (c) 2000 American Institute of Physics.

  20. A new paradigm for petascale Monte Carlo simulation: Replica exchange Wang Landau sampling

    SciTech Connect

    Li, Ying Wai; Vogel, Thomas; Wuest, Thomas; Landau, David P

    2014-01-01

    We introduce a generic, parallel Wang Landau method that is naturally suited to implementation on massively parallel, petaflop supercomputers. The approach introduces a replica-exchange framework in which densities of states for overlapping sub-windows in energy space are determined iteratively by traditional Wang Landau sampling. The advantages and general applicability of the method are demonstrated for several distinct systems that possess discrete or continuous degrees of freedom, including those with complex free energy landscapes and topological constraints.

  1. Representation of the Heisenberg Algebra h4 by the Lowest Landau Levels and Their Coherent States

    NASA Astrophysics Data System (ADS)

    Fakhri, H.; Shadman, Z.

    Using simultaneous shape invariance with respect to two different parameters, we introduce a pair of appropriate operators which realize shape invariance symmetry for the monomials on a half-axis. It leads to the derivation of rotational symmetry and dynamical symmetry group H4 with infinite-fold degeneracy for the lowest Landau levels. This allows us to represent the Heisenberg-Lie algebra h4 not only by the lowest Landau levels, but also by their corresponding standard coherent states.

  2. FROM THE HISTORY OF PHYSICS: L D Landau in the Soviet Atomic Project: a documentary study

    NASA Astrophysics Data System (ADS)

    Kiselev, G. V.

    2008-09-01

    The article presents information about the participation of Academician L D Landau in the Soviet Atomic Project and is based on a study of archive documents of the First Main Directorate. Their analysis points to L D Landau's important contribution to the development of the theory of heterogeneous nuclear reactors and to the computational justification of the first designs of atomic and hydrogen bombs. Many of the quoted documents have never been published before.

  3. Landau-Zener problem in a three-level neutrino system with nonlinear time dependence

    SciTech Connect

    Keraenen, P.; Maalampi, J.; Myyrylaeinen, M.; Riittinen, J.

    2007-02-01

    We consider the level-crossing problem in a three-level system with nonlinearly time-varying Hamiltonian (time-dependence t{sup -3}). We study the validity of the so-called independent crossing approximation in the Landau-Zener model by making comparison with results obtained numerically in the density matrix approach. We also demonstrate the failure of the so-called 'nearest zero' approximation of the Landau-Zener level-crossing probability integral.

  4. Attractive Hubbard model: Homogeneous Ginzburg-Landau expansion and disorder

    NASA Astrophysics Data System (ADS)

    Kuchinskii, E. Z.; Kuleeva, N. A.; Sadovskii, M. V.

    2016-02-01

    We derive a Ginzburg-Landau (GL) expansion in the disordered attractive Hubbard model within the combined Nozieres-Schmitt-Rink and DMFT+Σ approximation. Restricting ourselves to the homogeneous expansion, we analyze the disorder dependence of GL expansion coefficients for a wide range of attractive potentials U, from the weak BCS coupling region to the strong-coupling limit, where superconductivity is described by Bose-Einstein condensation (BEC) of preformed Cooper pairs. We show that for the a semielliptic "bare" density of states of the conduction band, the disorder influence on the GL coefficients A and B before quadratic and quartic terms of the order parameter, as well as on the specific heat discontinuity at the superconducting transition, is of a universal nature at any strength of the attractive interaction and is related only to the general widening of the conduction band by disorder. In general, disorder growth increases the values of the coefficients A and B, leading either to a suppression of the specific heat discontinuity (in the weak-coupling limit), or to its significant growth (in the strong-coupling region). However, this behavior actually confirms the validity of the generalized Anderson theorem, because the disorder dependence of the superconducting transition temperature T c, is also controlled only by disorder widening of the conduction band (density of states).

  5. Alfven soliton and multisoliton dynamics perturbed by nonlinear Landau damping

    SciTech Connect

    Sanchez-Arriaga, G.

    2010-08-15

    The evolution of weakly dispersive nonlinear Alfven waves propagating either parallel or oblique to the ambient magnetic field is investigated through the derivative nonlinear Schroedinger equation (DNLS) perturbed by nonlinear Landau damping. The dynamics is analyzed with the aid of a numeric algorithm based on the inverse scattering transform (IST) and an adiabatic model that takes advantages of the perturbed DNLS invariants. Both techniques are applied to five types of DNLS soliton and multisoliton solutions: (i) the parallel Alfven soliton, (ii) the bright and dark one-parameter oblique, (iii) the breather two-parameter oblique, (iv) two parallel Alfven solitons, and (v) the combination of a dark and a bright oblique solitons. For the parallel solitons, the adiabatic model describes correctly the dynamics and it also recovers the well-known result given by the perturbed IST. Due to the radiation emission and the formation of dark solitons, the behavior of oblique solitons is more complicated and multisoliton solutions are required in the adiabatic model. The analysis shows that parallel solitons develop into the normal regime, whereas the oblique waves leads to the formation of dark solitons and breathers with a wavepacket form.

  6. Fear and loathing in the lowest Landau level

    SciTech Connect

    Arovas, D.P.

    1986-01-01

    The standard incompressible fluid theory of the fractional quantized Hall effect is reviewed. A new approach to the problem is then proposed, which is based on a loop-gas picture of exchange condensation in an interacting two-dimensional electron gas. This cooperative ring-exchange theory describes a transition from a low-density, sparse ring phase (a Wigner crystal) to a higher-density ring condensate (the fractional quantized Hall phase) at a critical value of the Landau level-filling fraction, v = nhc/eB. The phase transition is inferred from the behavior of the many-body partition function, which is expressed as a trace over ring-exchange events, each contribution being approximated in a semiclassical path integral formalism. Like the fluid, the dense ring condensate is incompressible and supports fractionally charged quasi-particle excitations. Also formulated is an effective Hamiltonian for the collective-mode problem, which predicts a stiffening of the Wigner-lattice magnetophonons in the presence of a dense exchange phase. This latter result is presently only qualitative, for the collective-mode gap in the fluid theory has not been reproduced. Though speculative at this stage, the cooperative ring-exchange picture, unlike the standard one, clearly identifies an instability that drives a transition into the condensed phase.

  7. Landau Theory of Trifluoride Negative Thermal Expansion Materials

    NASA Astrophysics Data System (ADS)

    Guzman-Verri, Gian; Brierley, Richard; Littlewood, Peter

    Negative thermal expansion (NTE) is a desirable property in designing materials that are dimensionally stable and resistant to thermal shocks. Transition metal trifluorides (MF3, M=Al, Cr, Fe, Ga, In, Ti, V) are a class of materials with ReO3 structure that exhibit large, isotropic, and tunable NTE over a wide temperature range, which makes them attractive material candidates. They exhibit large coefficients of thermal expansion near their cubic-to-rhombohedral structural phase change, which can be thermally or pressure induced. Though they have recently been the subject of intense experimental research, little work has been done on the theory side and it has almost exclusively focused on zero temperature properties. In this talk, we construct a simple Landau theory of trifluorides and use it to calculate the temperature dependence of the elastic constants, soft phonon frequencies, and volume expansion near their structural transition. We compare our results to existing experimental data on trifluorides. Work at the U of Costa Rica is supported by the Vicerrectoria de Investigacion under Project No. B5220. Work at Argonne Natl Lab is supported by the U.S. Department of Energy, Office of Basic Energy Sciences under Contract No. DE-AC02-06CH11357.

  8. Landau quantization in the spinning cosmic string spacetime

    SciTech Connect

    Muniz, C.R.; Bezerra, V.B.; Cunha, M.S.

    2014-11-15

    We analyze the quantum phenomenon arising from the interaction of a spinless charged particle with a rotating cosmic string, under the action of a static and uniform magnetic field parallel to the string. We calculate the energy levels of the particle in the non-relativistic approach, showing how these energies depend on the parameters involved in the problem. In order to do this, we solve the time independent Schrödinger equation in the geometry of the spinning cosmic string, taking into account that the coupling between the rotation of the spacetime and the angular momentum of the particle is very weak, such that makes sense to apply the Schrödinger equation in a curved background whose metric has an off diagonal term which involves time and space. It is also assumed that the particle orbits sufficiently far from the boundary of the region of closed timelike curves which exist around this topological defect. Finally, we find the Landau levels of the particle in the presence of a spinning cosmic string endowed with internal structure, i.e., having a finite width and uniformly filled with both material and vacuum energies. - Highlights: • Solution of the wave equation characterizing the problem. • Energy levels of the particle in spacetime of the structureless string. • Expression for an analogous of the quadratic Zeeman effect. • Energy levels of the particle in spacetime of the string with internal structure. • Evidence of the string structure by the internal existence of the vacuum energy.

  9. Quantum criticality: beyond the Landau-Ginzburg-Wilson paradigm

    NASA Astrophysics Data System (ADS)

    Sachdev, Subir

    2004-03-01

    I will describe a variety of quantum critical points in metal and insulators which do not fall into the conventional Landau-Ginzburg-Wilson framework of fluctuating order parameters. In some cases, one of the phases adjoining the critical point is characterized by topological order and emergent gauge excitations, such as the fractionalized Fermi liquid (T. Senthil, S. Sachdev, and M. Vojta, Phys. Rev. Lett. 90), 216403 (2003).; the quantum critical point is characterized by non-Fermi liquid behavior in its thermodynamic and transport properties. In other cases(T. Senthil, A. Vishwanath, L. Balents, S. Sachdev, and M.P.A. Fisher, cond-mat/0311326.), both phases adjoining the critical point are characterized only by conventional order parameters and do not possess any fractionalized excitations: nevertheless, the critical theory is expressed in terms of fractionalized degrees of freedom and contains emergent gauge modes. The quantum `disordering' transition of the S=1/2 antiferromagnet with Neel order on the square lattice falls into the latter class (in this case the `disordered' phase has conventional valence bond order). I will comment on the broader implications of our results for the experimental study of quantum criticality in metals, insulators and superconductors.

  10. Solitary pulses in linearly coupled Ginzburg-Landau equations.

    PubMed

    Malomed, Boris A

    2007-09-01

    This article presents a brief review of dynamical models based on systems of linearly coupled complex Ginzburg-Landau (CGL) equations. In the simplest case, the system features linear gain, cubic nonlinearity (possibly combined with cubic loss), and group-velocity dispersion (GVD) in one equation, while the other equation is linear, featuring only intrinsic linear loss. The system models a dual-core fiber laser, with a parallel-coupled active core and an additional stabilizing passive (lossy) one. The model gives rise to exact analytical solutions for stationary solitary pulses (SPs). The article presents basic results concerning stability of the SPs; interactions between pulses are also considered, as are dark solitons (holes). In the case of the anomalous GVD, an unstable stationary SP may transform itself, via the Hopf bifurcation, into a stable localized breather. Various generalizations of the basic system are briefly reviewed too, including a model with quadratic (second-harmonic-generating) nonlinearity and a recently introduced model of a different but related type, based on linearly coupled CGL equations with cubic-quintic nonlinearity. The latter system features spontaneous symmetry breaking of stationary SPs, and also the formation of stable breathers. PMID:17903024

  11. Finite dimensionality in the complex Ginzburg-Landau equation

    SciTech Connect

    Doering, C.R.; Gibbon, J.D.; Holm, D.D.; Nicolaenko, B.

    1987-01-01

    Finite dimensionality is shown to exist in the complex Ginzburg-Landau equation periodic on the interval (0,1). A cone condition is derived and explained which gives upper bounds on the number of Fourier modes required to span the universal attractor and hence upper bounds on the attractor dimension itself. In terms of the parameter R these bounds are not large. For instance, when vertical bar ..mu.. vertical bar less than or equal to ..sqrt..3, the Fourier spanning dimension is 0(R/sup 3/2/). Lower bounds are estimated from the number of unstable side-bands using ideas from work on the Eckhaus instability. Upper bounds on the dimension of the attractor itself are obtained by bounding (or, for vertical bar ..mu.. vertical bar less than or equal to ..sqrt..3, computing exactly) the Lyapunov dimension and invoking a recent theorem of Constantin and Foias, which asserts that the Lyapunov dimension, defined by the Kaplan-Yorke formula, is an upper bound on the Hausdorff dimension. 39 refs., 7 figs.

  12. Landau levels and longitudinal magnetoresistance in generalized Weyl semimetals

    NASA Astrophysics Data System (ADS)

    Li, Xiao; Roy, Bitan

    The notion of axial anomaly is a venerable concept in quantum field theory that has received ample attention in condensed matter physics due to the discovery of Weyl materials (WSMs). In such systems Kramers non-degenerate bands touch at isolated points in the Brillouin zone that act as (anti)monopoles of Berry flux, and the monopole number (m) defines the topological invariant of the system. Although so far only simple WSMs (with m = 1) has been found in various inversion and/or time-reversal asymmetric systems, generalized Weyl semimetals with m > 1 can also be found in nature, for example double-Weyl semimetals in HgCr2Se4 and SrSi2 and triple-Weyl semimetals. In this work, we demonstrate the Landau level spectrum in generalized Weyl systems and its ramification on longitudinal magnetotransport measurements. We show that in the quantum limit generalized Weyl semimetals display negative longitudinal magnetoresistance due to the chiral anomaly. Moreover, the magnetoresistance has nontrivial dependence on the relative orientation of the external fields with the crystallographic axis, stemming from underlying anisotropic quasiparticle dispersion in the pristine system. Our theory can thus provide diagnostic tools to pin the quasiparticle properties in Weyl systems.

  13. Landau Theory for the Normal Solid-Supersolid Transition

    NASA Astrophysics Data System (ADS)

    Dorsey, Alan; Goldbart, Paul; Toner, John

    2006-03-01

    Kim and Chan [1,2] have reported an anomalous decoupling transition of solid ^4He in a torsional oscillator measurement, and interpret their results as evidence for non-classical rotational inertia and a possible supersolid phase of ^4He. Motivated by these results, we [3] have developed a phenomenological Landau theory of the normal-solid to supersolid (NS-SS) transition in which superfluidity is coupled to the elasticity of the crystalline ^4He lattice. We find that the elasticity does not affect the universal properties of the superfluid transition, so that in an unstressed crystal the well-known λ-anomaly in the heat capacity of the superfluid transition should also appear at the NS-SS transition. We also find that the onset of supersolidity leads to anomalies in the elastic constants near the transition, that should be observable in sound speed measurements; conversely, inhomogeneous strains in the lattice can induce local variations of the superfluid transition temperature, leading to a broadened transition. [1] E. Kim and M. H. W. Chan, Nature (London) 427, 225 (2004). [2] E. Kim and M. H. W. Chan, Science 305, 1941 (2004). [3] A. T. Dorsey, P. M. Goldbart, and J. Toner, cond-mat/0508271.

  14. Landau levels in uniaxially strained graphene: A geometrical approach

    SciTech Connect

    Betancur-Ocampo, Y. Cifuentes-Quintal, M.E.; Cordourier-Maruri, G.; Coss, R. de

    2015-08-15

    The effect of strain on the Landau levels (LLs) spectra in graphene is studied, using an effective Dirac-like Hamiltonian which includes the distortion in the Dirac cones, anisotropy and spatial-dependence of the Fermi velocity induced by the lattice change through a renormalized linear momentum. We propose a geometrical approach to obtain the electron’s wave-function and the LLs in graphene from the Sturm–Liouville theory, using the minimal substitution method. The coefficients of the renormalized linear momentum are fitted to the energy bands, which are obtained from a Density Functional Theory (DFT) calculation. In particular, we evaluate the case of Dirac cones with an ellipsoidal transversal section resulting from uniaxially strained graphene along the Arm-Chair (AC) and Zig-Zag (ZZ) directions. We found that uniaxial strain in graphene induces a contraction of the LLs spectra for both strain directions. Also, is evaluated the contribution of the tilting of Dirac cone axis resulting from the uniaxial deformations to the contraction of the LLs spectra. - Highlights: • The LLs in uniaxially strained graphene are found using a geometrical approach. • The energy of the LLs in function of the Dirac cone deformation is presented. • We found that uniaxial strain in graphene induces a contraction of the LLs spectra. • Contraction in LLs spectra depends on the geometrical parameters of the Dirac cone.

  15. Ginzburg-Landau modeling of Nano-SQUIDs

    NASA Astrophysics Data System (ADS)

    Kirtley, John; Hazra, Dibyendu; Hasselbach, Klaus; Buisson, Olivier

    2014-03-01

    NanoSQUIDs are micron-sized Superconducting Quantum Interference Devices with narrow (50 nm) sized constrictions as weak links. They are used for, e.g., studying switching dynamics in magnetic nanoparticles and high spatial resolution magnetic microscopy. When the constriction dimensions become comparable to or larger than the superconducting coherence length, the current-phase relations become non-sinusoidal, reducing the flux modulation depth and increasing the thermally activated flux noise. We have numerically solved the Ginzburg-Landau (GL) equations for the nanoSQUID geometry to obtain current-phase relations, the dependence of critical current on magnetic flux, and the thermally activated escape rates. We predict NanoSQUIDs with short coherence lengths to have critical current distribution widths, and therefore flux noises, proportional to T1/2, as opposed to tunnel junction SQUIDs, which are proportional to T2/3. Our GL simulations predict that the ultimate noise performance of Al nanoSQUIDs, with their longer coherence lengths, should be better than Nb nanoSQUIDs, with suspended bridge Al/Nb nanoSQUIDs intermediate between the two.

  16. Quantum integrability in the multistate Landau-Zener problem

    NASA Astrophysics Data System (ADS)

    Patra, A.; Yuzbashyan, E. A.

    2015-06-01

    We analyze Hamiltonians linear in the time variable for which the multistate Landau-Zener (LZ) problem is known to have an exact solution. We show that they either belong to families of mutually commuting Hamiltonians polynomial in time or reduce to the 2× 2 LZ problem, which is considered trivially integrable. The former category includes the equal slope, bow-tie, and generalized bow-tie models. For each of these models we explicitly construct the corresponding families of commuting matrices. The equal slope model is a member of an integrable family that consists of the maximum possible number (for a given matrix size) of commuting matrices linear in time. The bow-tie model belongs to a previously unknown, similarly maximal family of quadratic commuting matrices. We thus conjecture that quantum integrability understood as the existence of nontrivial parameter-dependent commuting partners is a necessary condition for the LZ solvability. Descendants of the 2× 2 LZ Hamiltonian are e.g. general SU(2) and SU(1,1) Hamiltonians, time-dependent linear chain, linear, nonlinear, and double oscillators. We explicitly obtain solutions to all these LZ problems from the 2× 2 case.

  17. On quantum integrability of the Landau-Lifshitz model

    SciTech Connect

    Melikyan, A.; Pinzul, A.

    2009-10-15

    We investigate the quantum integrability of the Landau-Lifshitz (LL) model and solve the long-standing problem of finding the local quantum Hamiltonian for the arbitrary n-particle sector. The particular difficulty of the LL model quantization, which arises due to the ill-defined operator product, is dealt with by simultaneously regularizing the operator product and constructing the self-adjoint extensions of a very particular structure. The diagonalizibility difficulties of the Hamiltonian of the LL model, due to the highly singular nature of the quantum-mechanical Hamiltonian, are also resolved in our method for the arbitrary n-particle sector. We explicitly demonstrate the consistency of our construction with the quantum inverse scattering method due to Sklyanin [Lett. Math. Phys. 15, 357 (1988)] and give a prescription to systematically construct the general solution, which explains and generalizes the puzzling results of Sklyanin for the particular two-particle sector case. Moreover, we demonstrate the S-matrix factorization and show that it is a consequence of the discontinuity conditions on the functions involved in the construction of the self-adjoint extensions.

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Direct observation of Landau levels of massless and massive Dirac fermions.

    NASA Astrophysics Data System (ADS)

    Li, Guohong; Andrei, Eva Y.

    2007-03-01

    The low energy quasiparticles in graphene resemble massless relativistic particles (Dirac fermions): they have a linear energy-momentum spectrum and possess internal degrees of freedom arising from the crystal symmetry of the honeycomb lattice, leading to particle anti-particle pairs. When two layers of graphene are coupled together, the quasiparticles acquire a band-mass and are transformed into chiral massive fermions. Both types of quasiparticles develop unusual Landau levels in a magnetic field which profoundly alter the magneto-transport properties. We will report the direct observation of the Landau levels associated with these quasiparticles using a low temperature STM in fields up to 12 Tesla. The experiments reveal two independent sequences of Landau levels that provide evidence for the coexistence of massless and massive Dirac fermions. The energy levels of the former exhibit a square-root dependence on both field and Landau-level index n, while the latter are linear in field with a Landau-level index dependence of [n(n+1)]^1/2. Both sequences exhibit a zero energy Landau level which is a unique and direct consequence of the quantum-relativistic nature of these quasiparticles.

  20. van der Waals torque

    NASA Astrophysics Data System (ADS)

    Esquivel-Sirvent, Raul; Schatz, George

    2014-03-01

    The theory of generalized van der Waals forces by Lifshtz when applied to optically anisotropic media predicts the existence of a torque. In this work we present a theoretical calculation of the van der Waals torque for two systems. First we consider two isotropic parallel plates where the anisotropy is induced using an external magnetic field. The anisotropy will in turn induce a torque. As a case study we consider III-IV semiconductors such as InSb that can support magneto plasmons. The calculations of the torque are done in the Voigt configuration, that occurs when the magnetic field is parallel to the surface of the slabs. The change in the dielectric function as the magnetic field increases has the effect of decreasing the van der Waals force and increasing the torque. Thus, the external magnetic field is used to tune both the force and torque. The second example we present is the use of the torque in the non retarded regime to align arrays of nano particle slabs. The torque is calculated within Barash and Ginzburg formalism in the nonretarded limit, and is quantified by the introduction of a Hamaker torque constant. Calculations are conducted between anisotropic slabs of materials including BaTiO3 and arrays of Ag nano particles. Depending on the shape and arrangement of the Ag nano particles the effective dielectric function of the array can be tuned as to make it more or less anisotropic. We show how this torque can be used in self assembly of arrays of nano particles. ref. R. Esquivel-Sirvent, G. C. Schatz, Phys. Chem C, 117, 5492 (2013). partial support from DGAPA-UNAM.

  1. Zeit im Wandel der Zeit.

    NASA Astrophysics Data System (ADS)

    Aichelburg, P. C.

    Contents: Einleitung(P. C. Aichelburg). 1. Über Zeit, Bewegung und Veränderung (Aristoteles). 2. Ewigkeit und Zeit (Plotin). 3. Was ist die Zeit? (Augustinus). 4. Von der Zeit (Immanuel Kant). 5. Newtons Ansichten über Zeit, Raum und Bewegung (Ernst Mach). 6. Über die mechanische Erklärung irreversibler Vorgänge (Ludwig Boltzmann). 7. Das Maß der Zeit (Henri Poincaré). 8. Dauer und Intuition (Henri Bergson). 9. Die Geschichte des Unendlichkeitsproblems (Bertrand Russell). 10. Raum und Zeit (Hermann Minkowski). 11. Der Unterschied von Zeit und Raum (Hans Reichenbach). 12. Newtonscher und Bergsonscher Zeitbegriff (Norbert Wiener). 13. Die Bildung des Zeitbegriffs beim Kinde (JeanPiaget).14. Eine Bemerkung über die Beziehungen zwischen Relativitätstheorie und der idealistischen Philosophie (Kurt Gödel). 15. Der zweite Hauptsatz und der Unterschied von Vergangenheit und Zukunft (Carl Friedrich v. Weizsäcker). 16. Zeit als physikalischer Begriff (Friedrich Hund). 17. Zeitmessung und Zeitbegriff in der Astronomie (Otto Heckmann). 18. Kann die Zeit rückwärts gehen? (Martin Gardner). 19. Zeit und Zeiten (Ilya Prigogine, Isabelle Stengers). 20. Zeit als dynamische Größe in der Relativitätstheorie (P. C. Aichelburg).

  2. Time-asymptotic field amplitudes in nonlinear Landau damping

    SciTech Connect

    Buchanan, M.; Kirkitelos, P.; Dorning, J.J. )

    1993-01-01

    The behavior of an electrostatic plasma wave of initial amplitude Ei in a collisionless electron plasma depends crucially on the ratio [delta] = [gamma]L/[omega]B, where [gamma]L is the damping coefficient calculated from linear plasma kinetic theory and [omega]B = (ekEi/m)[sup 1/2] is the [open quotes]bounce[close quotes] frequency for trapped electrons. For sufficiently small E[sub i], i.e., [delta] [much gt] 1, the wave damps away completely; conversely, a wave of large initial amplitude, for which [delta] [much lt] 1, saturates at a finite final amplitude due to the nonlinear effects of particle trapping. In this paper, we report results concerning the transition region [delta] [approximately] 0(1), which separates these two regimes. For the case of weak damping, i.e., [vert bar][gamma]L/[omega]p[vert bar][much lt]1, where [omega]p is the plasma frequency, we calculate analytically the critical value [delta][sub i,e] below which complete damping occurs and derive the first explicit analytic relationship between E[sub i] and E[sub f], the time-asymptotic amplitude, for E[sub i] above the critical value E[sub i,c] = (m,ek)([gamma]L/[delta][sub i,c]). The results predict an interesting phenomenon - a finite jump [delta]E in the final field amplitude as E[sub i] is increased through E[sub i,c]. We have corroborated the reality of this phenomenon through large-scale numerical simulations of the Vlasov-Poisson system, carried out using the spectral splitting code of Klimas. These important new results establish a detailed picture of the fundamental transition between linear and nonlinear Landau damping and, in particular, show that the onset of essentially nonlinear behavior occurs very abruptly as the initial wave amplitude increases through its critical value.

  3. Das Lob der Sternkunst. Astronomie in der deutschen Aufklärung.

    NASA Astrophysics Data System (ADS)

    Baasner, R.

    Contents: 1. Einleitung. 2. Die Astronomie im Rahmen der Aufklärungs-Physik. 3. Das Lob der Sternkunst. 4. Ein Blick auf die Sternwarten. 5. Allgemeine Darstellungen der Sternkunde. 6. Schleppende Rezeption: Das kopernikanische Weltbild. 7. Himmelsphysik: Die Debatte um die causa gravitatis. 8. Theorie der Himmelskörper. 9. Die Erde als Gegenstand der Astronomie. 10. Die Sonne. 11. Der Mond. 12. Die Planeten. 13. Die Kometen. 14. Die Fixsterne. 15. Die Entstehung der Welt. 16. Beiträge der Astrotheologie. 17. Der Kampf gegen die Astrologen.

  4. Landau damping effects on dust-acoustic solitary waves in a dusty negative-ion plasma

    SciTech Connect

    Barman, Arnab; Misra, A. P. E-mail: apmisra@gmail.com

    2014-07-15

    The nonlinear theory of dust-acoustic waves (DAWs) with Landau damping is studied in an unmagnetized dusty negative-ion plasma in the extreme conditions when the free electrons are absent. The cold massive charged dusts are described by fluid equations, whereas the two-species of ions (positive and negative) are described by the kinetic Vlasov equations. A Korteweg-de Vries (KdV) equation with Landau damping, governing the dynamics of weakly nonlinear and weakly dispersive DAWs, is derived following Ott and Sudan [Phys. Fluids 12, 2388 (1969)]. It is shown that for some typical laboratory and space plasmas, the Landau damping (and the nonlinear) effects are more pronounced than the finite Debye length (dispersive) effects for which the KdV soliton theory is not applicable to DAWs in dusty pair-ion plasmas. The properties of the linear phase velocity, solitary wave amplitudes (in presence and absence of the Landau damping) as well as the Landau damping rate are studied with the effects of the positive ion to dust density ratio (μ{sub pd}) as well as the ratios of positive to negative ion temperatures (σ) and masses (m)

  5. Landau damping effects on dust-acoustic solitary waves in a dusty negative-ion plasma

    NASA Astrophysics Data System (ADS)

    Barman, Arnab; Misra, A. P.

    2014-07-01

    The nonlinear theory of dust-acoustic waves (DAWs) with Landau damping is studied in an unmagnetized dusty negative-ion plasma in the extreme conditions when the free electrons are absent. The cold massive charged dusts are described by fluid equations, whereas the two-species of ions (positive and negative) are described by the kinetic Vlasov equations. A Korteweg-de Vries (KdV) equation with Landau damping, governing the dynamics of weakly nonlinear and weakly dispersive DAWs, is derived following Ott and Sudan [Phys. Fluids 12, 2388 (1969)]. It is shown that for some typical laboratory and space plasmas, the Landau damping (and the nonlinear) effects are more pronounced than the finite Debye length (dispersive) effects for which the KdV soliton theory is not applicable to DAWs in dusty pair-ion plasmas. The properties of the linear phase velocity, solitary wave amplitudes (in presence and absence of the Landau damping) as well as the Landau damping rate are studied with the effects of the positive ion to dust density ratio (μpd) as well as the ratios of positive to negative ion temperatures (σ) and masses (m).

  6. More on Gribov copies and propagators in Landau-gauge Yang-Mills theory

    SciTech Connect

    Maas, Axel

    2009-01-01

    Fixing a gauge in the nonperturbative domain of Yang-Mills theory is a nontrivial problem due to the presence of Gribov copies. In particular, there are different gauges in the nonperturbative regime which all correspond to the same definition of a gauge in the perturbative domain. Gauge-dependent correlation functions may differ in these gauges. Two such gauges are the minimal Landau gauge and the absolute Landau gauge, both corresponding to the perturbative Landau gauge. These, and their numerical implementation, are described and presented in detail. Other choices will also be discussed. This investigation is performed, using numerical lattice gauge theory calculations, by comparing the propagators of gluons and ghosts for the minimal Landau gauge and the absolute Landau gauge in SU(2) Yang-Mills theory. It is found that the propagators are different in the far infrared and even at energy scales of the order of half a GeV. In particular, the finite-volume effects are also modified. This is observed in two and three dimensions. Some remarks on the four-dimensional case are provided as well.

  7. Landau-Zener transitions mediated by an environment: Population transfer and energy dissipation

    SciTech Connect

    Dodin, Amro; Simine, Lena; Segal, Dvira; Garmon, Savannah

    2014-03-28

    We study Landau-Zener transitions between two states with the addition of a shared discretized continuum. The continuum allows for population decay from the initial state as well as indirect transitions between the two states. The probability of nonadiabatic transition in this multichannel model preserves the standard Landau-Zener functional form except for a shift in the usual exponential factor, reflecting population transfer into the continuum. We provide an intuitive explanation for this behavior assuming individual, independent transitions between pairs of states. In contrast, the ground state survival probability at long time shows a novel, non-monotonic, functional form with an oscillatory behavior in the sweep rate at low sweep rate values. We contrast the behavior of this open-multistate model to other generalized Landau-Zener models incorporating an environment: the stochastic Landau-Zener model and the dissipative case, where energy dissipation and thermal excitations affect the adiabatic region. Finally, we present evidence that the continuum of states may act to shield the two-state Landau-Zener transition probability from the effect of noise.

  8. Landau-Zener transitions mediated by an environment: population transfer and energy dissipation.

    PubMed

    Dodin, Amro; Garmon, Savannah; Simine, Lena; Segal, Dvira

    2014-03-28

    We study Landau-Zener transitions between two states with the addition of a shared discretized continuum. The continuum allows for population decay from the initial state as well as indirect transitions between the two states. The probability of nonadiabatic transition in this multichannel model preserves the standard Landau-Zener functional form except for a shift in the usual exponential factor, reflecting population transfer into the continuum. We provide an intuitive explanation for this behavior assuming individual, independent transitions between pairs of states. In contrast, the ground state survival probability at long time shows a novel, non-monotonic, functional form with an oscillatory behavior in the sweep rate at low sweep rate values. We contrast the behavior of this open-multistate model to other generalized Landau-Zener models incorporating an environment: the stochastic Landau-Zener model and the dissipative case, where energy dissipation and thermal excitations affect the adiabatic region. Finally, we present evidence that the continuum of states may act to shield the two-state Landau-Zener transition probability from the effect of noise. PMID:24697472

  9. Bloch-Landau-Zener dynamics in single-particle Wannier-Zeeman systems

    NASA Astrophysics Data System (ADS)

    Ke, Yongguan; Qin, Xizhou; Zhong, Honghua; Huang, Jiahao; He, Chunshan; Lee, Chaohong

    2015-05-01

    Stimulated by the experimental realization of spin-dependent tunneling via a gradient magnetic field [C. J. Kennedy et al., Phys. Rev. Lett. 111, 225301 (2013);, 10.1103/PhysRevLett.111.225301 M. Aidelsburger et al., Phys. Rev. Lett. 111, 185301 (2013), 10.1103/PhysRevLett.111.185301], we investigate the dynamics of Bloch oscillations and Landau-Zener tunneling of single spin-half particles in a periodic potential under the influence of a spin-dependent constant force. In analogy to the Wannier-Stark system, we call our system the Wannier-Zeeman system. If there is no coupling between the two spin states, the system can be described by two crossing Wannier-Stark ladders with opposite tilts. The spatial crossing between two Wannier-Stark ladders becomes a spatial anticrossing if the two spin states are coupled by external fields. For a wave packet away from the spatial anticrossing, due to the spin-dependent constant force, it will undergo spatial Landau-Zener transitions assisted by the intrinsic intraband Bloch oscillations, which we call the Bloch-Landau-Zener dynamics. If the interspin coupling is sufficiently strong, the system undergoes adiabatic Bloch-Landau-Zener dynamics, in which the spin dynamics follows the local dressed states. Otherwise, for nonstrong interspin couplings, the system undergoes nonadiabatic Bloch-Landau-Zener dynamics.

  10. Growth rate and the cutoff wavelength of the Darrieus-Landau instability in laser ablation

    SciTech Connect

    Modestov, Mikhail; Bychkov, Vitaly; Valiev, Damir; Marklund, Mattias

    2009-10-15

    The main characteristics of the linear Darrieus-Landau instability in the laser ablation flow are investigated. The dispersion relation of the instability is found numerically as a solution to an eigenvalue stability problem, taking into account the continuous structure of the flow. The results are compared to the classical Darrieus-Landau instability of a usual slow flame. The difference between the two cases is due to the specific features of laser ablation: sonic velocities of hot plasma and strong temperature dependence of thermal conduction. It is demonstrated that the Darrieus-Landau instability in laser ablation is much stronger than in the classical case. In particular, the maximum growth rate in the case of laser ablation is about three times larger than that for slow flames. The characteristic length scale of the Darrieus-Landau instability in the ablation flow is comparable to the total distance from the ablation zone to the critical zone of laser light absorption. The possibility of experimental observations of the Darrieus-Landau instability in laser ablation is discussed.

  11. Biochips und ihr Einsatz in der Lebensmittelanalytik

    NASA Astrophysics Data System (ADS)

    Huber, Ingrid; Zeltz, Patric

    Mit der Verbreitung des Begriffes "Biochip“ in den biotechnologischen Medien wurde Ende der 1990er-Jahre zunächst der Eindruck erweckt, dass die Computerelektronik in die molekularbiologischen Anwendungen eingestiegen ist [18]. In nur wenigen Jahren hat sich die Biochiptechnologie zu einem Verfahren entwickelt, das aus der molekularbiologischen Grundlagenforschung nicht mehr wegzudenken ist und über eine Vielzahl von Einsatzbereichen verfügt. Die Biochiptechnologie ermöglicht die Miniaturisierung von DNA-, RNA- bzw. Proteinanalytik in hochparallelen Formaten. Dieser hohe Parallelisierungsgrad ist einer der wesentlichen Vorteile dieser Technik gegenüber klassischen molekularbiologischen Methoden. Sie wird heutzutage vor allem in der Genomforschung eingesetzt, für Genexpressionsstudien, zum Screening von single nucleotide polymorphisms (SNPs), in der pharmakogenetischen Forschung sowie in der Erforschung von Erbkrankheiten und in der Krebsforschung [1, 7, 19]. Neben vielen weiteren Bereichen finden Biochips auch spezielle Anwendungen in der Lebensmittelanalytik.

  12. Dialektischer Materialismus in der Quantentheorie

    NASA Astrophysics Data System (ADS)

    Fuchs, Klaus

    Der absolute Determinismus der klassischen Mechanik bietet keine Ansatzpunkte für eine befriedigende Naturphilosophie. Mit der Quantenmechanik werden nicht lediglich die Unzulänglichkeiten einzelner klassischer Begriffe, sondern die des gesamten klassischen Begriffssystems beseitigt.Translated AbstractDialectical Materialism in Quantum TheoryThe absolute determinism of classical mechanics does not provide any base for a satisfactory philosophy of nature. In quantum mechanics the shortcomings of not only some single classical concepts but of the classical description as a whole are removed.

  13. Landau damping of the dust-acoustic surface waves in a Lorentzian dusty plasma slab

    NASA Astrophysics Data System (ADS)

    Lee, Myoung-Jae; Jung, Young-Dae

    2016-01-01

    Landau damping of a dust-acoustic surface wave propagating at the interfaces of generalized Lorentzian dusty plasma slab bounded by a vacuum is kinetically derived as the surface wave displays the symmetric and the anti-symmetric mode in a plasma slab. In the limiting case of small scaled wave number, we have found that Landau damping is enhanced as the slab thickness is increased. In particular, the damping of anti-symmetric mode is much stronger for a Lorentzian plasma than for a Maxwellian plasma. We have also found that the damping is more affected by superthermal particles in a Lorentzian plasma than by a Maxwellian plasma for both of the symmetric and the anti-symmetric cases. The variations of Landau damping with various parameters are also discussed.

  14. Spin and valley resolved Landau level crossing in tri-layer ABA stacked graphene

    NASA Astrophysics Data System (ADS)

    Datta, Biswajit; Gupta, Vishakha; Borah, Abhinandan; Watanabe, Kenji; Taniguchi, Takashi; Deshmukh, Mandar

    We present quantum Hall measurements on a high quality encapsulated tri-layer graphene device. Low temperature field effect mobility of this device is around 500,000 cm2/Vs and we see SdH oscillations at a magnetic field as low as 0.3 T. Quantum Hall measurements confirm that the chosen tri layer graphene is Bernal (ABA) stacked. Due to the presence of both mass-less monolayer like Dirac fermions and massive bi-layer like Dirac fermions in Bernal stacked tri-layer graphene, there are Landau level crossings between monolayer and bi-layer bands in quantum Hall regime. Although most of the Landau Level crossings are predominantly present on the electron sides, we also observe signatures of the crossings on the hole side. This behaviour is consistent with the asymmetry of electron and hole in ABA tri-layer graphene. We observe a series of crossings of the spin and valley resolved Landau Levels.

  15. Magnetic breakdown and Landau level spectra of a tunable double-quantum-well Fermi surface

    SciTech Connect

    Simmons, J.A.; Harff, N.E.; Lyo, S.K.; Klem, J.F.; Boebinger, G.S.; Pfeiffer, L.N.; West, K.W.

    1997-12-31

    By measuring longitudinal resistance, the authors map the Landau level spectra of double quantum wells as a function of both parallel (B{sub {parallel}}) and perpendicular (B{sub {perpendicular}}) magnetic fields. In this continuously tunable highly non-parabolic system, the cyclotron masses of the two Fermi surface orbits change in opposite directions with B{sub {parallel}}. This causes the two corresponding ladders of Landau levels formed at finite B{sub {perpendicular}} to exhibit multiple crossings. They also observe a third set of landau levels, independent of B{sub {parallel}}, which arise from magnetic breakdown of the Fermi surface. Both semiclassical and full quantum mechanical calculations show good agreement with the data.

  16. Nonlinear Landau resonant scattering of near equatorially mirroring radiation belt electrons by oblique EMIC waves

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Su, Zhenpeng; Zhang, Yan; Shi, Shengwei; Wang, Geng

    2016-04-01

    In response to solar wind disturbances, radiation belt (a few hundreds of keV to several MeV) electron fluxes can be depleted significantly over the entire equatorial pitch angle range. The frequently mentioned cyclotron resonant scattering is applicable only for electrons mirroring off the equator. Here we propose a new physical mechanism, nonlinear Landau resonance with oblique electromagnetic ion cyclotron (EMIC) waves, to effectively scatter the near equatorially mirroring electrons. Our test particle simulations show that the nonlinear Landau trapping can occur over a wide energy range and yield the net decrease in equatorial pitch angle Δαeq≈10° within several seconds. Our parametric studies further reveal that this nonlinear Landau-trapping process is favored by a low plasma density, an intense wave field, a high wave frequency close to ion gyrofrequencies, and a large wave normal angle.

  17. Doping-dependent intraband carrier dynamics in Landau-quantized graphene

    NASA Astrophysics Data System (ADS)

    Wendler, Florian; Malic, Ermin

    2016-01-01

    We investigate the intraband carrier dynamics in Landau-quantized graphene after an optical excitation with low-energetic terahertz pulses. Based on a microscopic theory, we calculate time-dependent differential transmission spectra reflecting the Landau-level dynamics. Our calculations reveal a strong dependence on the Fermi energy EF of the graphene sample as well as on the applied magnetic field B . We find that the pump pulse can lead to both absorption bleaching and absorption enhancement depending on B and the position of EF with respect to the resonant Landau-level transition. As a result, positive and negative contributions in differential transmission spectra appear, in good agreement with recent pump-probe measurements.

  18. Energy Scales of the Reentrant Integer Quantum Hall States in High Landau Levels

    NASA Astrophysics Data System (ADS)

    Deng, Nianpei; Watson, John; Manfra, Michael; Csathy, Gabor

    2013-03-01

    The reentrant integer quantum Hall states (RIQHS) have been identified with the electronic bubble phases. These bubble phases are exotic electronic solids similar to the Wigner crystal, but have more than one electron per lattice site. Recently we reported the presence of a peak in the temperature dependent magnetoresistence of the RIQHSs and we have associated this peak with the onset of the RIQHSs. We found that, contrary to the predictions of the bubble theory, the onset temperatures of the RIQHSs in the third Landau level are much higher than those in the second Landau level. We have extended such measurements of the onset temperatures to several high Landau levels. In this talk we will discuss the orbital dependence of the onset temperatures of RIQHSs and we will compare these quantitative results to the predictions of the bubble theory. This work was supported by the DOE BES contract no. DE-SC0006671.

  19. Interaction Energy of Domain Walls in a Nonlocal Ginzburg-Landau Type Model from Micromagnetics

    NASA Astrophysics Data System (ADS)

    Ignat, Radu; Moser, Roger

    2016-07-01

    We study a variational model from micromagnetics involving a nonlocal Ginzburg-Landau type energy for {S1}-valued vector fields. These vector fields form domain walls, called Néel walls, that correspond to one-dimensional transitions between two directions within the unit circle {S1}. Due to the nonlocality of the energy, a Néel wall is a two length scale object, comprising a core and two logarithmically decaying tails. Our aim is to determine the energy differences leading to repulsion or attraction between Néel walls. In contrast to the usual Ginzburg-Landau vortices, we obtain a renormalised energy for Néel walls that shows both a tail-tail interaction and a core-tail interaction. This is a novel feature for Ginzburg-Landau type energies that entails attraction between Néel walls of the same sign and repulsion between Néel walls of opposite signs.

  20. Evidence for nuclear Landau-Zener effect: New resonance mechanism in heavy-ion reactions

    SciTech Connect

    Abe, Y.; Park, J.Y.

    1983-12-01

    Characteristic resonancelike peaks recently observed in the angle-integrated inelastic cross sections for the /sup 13/C-/sup 17/O system are understood in terms of the Landau-Zener excitation mechanism at energy level crossings. Angle-integrated inelastic cross sections estimated with the Landau-Zener formula show a series of resonancelike peaks as a function of incident energy, each of which is associated with a grazing angular momentum of the relative motion between nuclei. Simple expressions are given for resonance energies and ''widths'' of new ''resonances.'' This resonance mechanism is a new one, which has not been known in nuclear reactions nor in atomic collisions, although it is based on the well-known Landau-Zener promotion mechanism.

  1. Manipulating the Majorana qubit with Landau-Zener-Stückelberg interference

    NASA Astrophysics Data System (ADS)

    Huang, Wen-Chao; Liang, Qi-Feng; Yao, Dao-Xin; Wang, Zhi

    2015-07-01

    Constructing a universal operation scheme for Majorana qubits remains a central issue for the topological quantum computation. We study the Landau-Zener-Stückelberg interference in a Majorana qubit and show that this interference can be used to achieve controllable operations. The Majorana qubit consists of an rf superconducting quantum interference device (SQUID) with a topological nanowire Josephson junction which hosts Majorana bound states. In the SQUID, a magnetic flux pulse can drive the quantum evolution of the Majorana qubit. The qubit experiences two Landau-Zener transitions when the amplitude of the pulse is tuned around the superconducting flux quanta h /2 e . The Landau-Zener-Stückelberg interference between the two transitions rotates the Majorana qubit, with the angle controlled by the time scale of the pulse. This rotation operation implements a high-speed single-qubit gate on the Majorana qubit, which is a necessary ingredient for the topological quantum computation.

  2. Landau levels of scalar QED in time-dependent magnetic fields

    SciTech Connect

    Kim, Sang Pyo

    2014-05-15

    The Landau levels of scalar QED undergo continuous transitions under a homogeneous, time-dependent magnetic field. We analytically formulate the Klein–Gordon equation for a charged spinless scalar as a Cauchy initial value problem in the two-component first order formalism and then put forth a measure that classifies the quantum motions into the adiabatic change, the nonadiabatic change, and the sudden change. We find the exact quantum motion and calculate the pair-production rate when the magnetic field suddenly changes as a step function. -- Highlights: •We study the Landau levels of scalar QED in time-dependent magnetic fields. •Instantaneous Landau levels make continuous transitions but keep parity. •The Klein–Gordon equation is expressed in the two-component first order formalism. •A measure is advanced that characterizes the quantum motions into three categories. •A suddenly changing magnetic field produces pairs of charged scalars from vacuum.

  3. The Darrieus-Landau instability in fast deflagration and laser ablation

    SciTech Connect

    Bychkov, Vitaly; Modestov, Mikhail; Marklund, Mattias

    2008-03-15

    The problem of the Darrieus-Landau instability at a discontinuous deflagration front in a compressible flow is solved. Numerous previous attempts to solve this problem suffered from the deficit of boundary conditions. Here, the required additional boundary condition is derived rigorously taking into account the internal structure of the front. The derived condition implies a constant mass flux at the front; it reduces to the classical Darrieus-Landau condition in the limit of an incompressible flow. It is demonstrated that in general the solution to the problem depends on the type of energy source in the flow. In the common case of a strongly localized source, compression effects make the Darrieus-Landau instability considerably weaker. Particularly, the instability growth rate is reduced for laser ablation in comparison to the classical incompressible case. The instability disappears completely in the Chapman-Jouguet regime of ultimately fast deflagration.

  4. Der evolutionäre Naturalismus in der Ethik

    NASA Astrophysics Data System (ADS)

    Kaiser, Marie I.

    Charles Darwin hat eindrucksvoll gezeigt, dass der Mensch ebenso wie alle anderen Lebewesen ein Produkt der biologischen Evolution ist. Die sich an Darwin anschließende Forschung hat außerdem plausibel gemacht, dass sich nicht nur viele der körperlichen Merkmale des Menschen, sondern auch (zumindest einige) seiner Verhaltensdispositionen in adaptiven Selektionsprozessen herausgebildet haben. Die Vorstellung, dass auch die menschliche Moralität evolutionär bedingt ist, scheint daher auf den ersten Blick ganz überzeugend. Schließlich hat die Evolutionstheorie in den vergangenen Jahrzehnten in vielen Bereichen (auch außerhalb der Biologie) ihre weitreichende Bedeutung unter Beweis gestellt. Warum sollte, so könnte man beispielsweise fragen, gerade die Fähigkeit des Menschen, moralische Normen aufzustellen und gemäß ihnen zu handeln, nicht evolutionär erklärt werden können? Und warum sollte eine solche evolutionäre Erklärung der menschlichen Moralität irrelevant für die Rechtfertigung moralischer Normen sein? Warum sollte die Ethik eine Bastion der Philosophen bleiben, für die evolutionsbiologische Forschungsergebnisse über den Menschen und seine nächsten Verwandten keinerlei Relevanz besitzen?

  5. Detuning, wavebreaking, and Landau damping as limiting effects on laser compression by resonant backward Raman scattering

    NASA Astrophysics Data System (ADS)

    Yampolsky, Nikolai

    2010-11-01

    Plasma waves mediate high-power pulse compression, where the persistence of the plasma wave is critical. In this scheme, the plasma wave mediates the energy transfer between long pump and short seed laser pulses through backward Raman scattering. High efficiency of the plasma wave excitation defines both the overall efficiency of the energy transfer and the duration of the amplified pulse. Based on recent extensive experiments, it is possible to deduce that the experimentally realized efficiency of the amplifier is likely constrained by two factors, namely the pump chirp and the plasma wavebreaking [1]. The limits arise because for compression the frequency of the plasma wave should match the bandwidth of the instability and the plasma wave amplitude should be small enough to be sustained by plasma. Both the detuning and the wavebreaking effects can be suppressed by using low pump intensity in plasma having the appropriate density gradient [1]. When these constraints are avoided, Landau damping will be the main limiting factor. However, the Landau damping rate can be significantly reduced in the presence of a strong plasma wave. Currently, nonlinear Landau damping can be described within two recently developed models [2,3]. We show that these two different descriptions result in the same dynamics for the plasma wave amplitude. We use the quasilinear description of nonlinear Landau damping [3] to identify a regime where initially high linear Landau damping can be significantly saturated. Because of the saturation effect, higher temperatures can be tolerated in achieving efficient amplification. Significantly, the plasma temperature can be as much as 50% larger compared to the case of unsaturated Landau damping.[4pt] [1] N.A. Yampolsky et al., Phys. Plasmas 15, 113104 (2008).[0pt] [2] D. Benisti et al., Phys. Rev. Lett. 103, 155002 (2009).[0pt] [3] N.A. Yampolsky and N.J. Fisch, Phys. Plasmas 16, 072104 (2009).

  6. Replica-exchange Wang Landau sampling: pushing the limits of Monte Carlo simulations in materials sciences

    SciTech Connect

    Perera, Meewanage Dilina N; Li, Ying Wai; Eisenbach, Markus; Vogel, Thomas; Landau, David P

    2015-01-01

    We describe the study of thermodynamics of materials using replica-exchange Wang Landau (REWL) sampling, a generic framework for massively parallel implementations of the Wang Landau Monte Carlo method. To evaluate the performance and scalability of the method, we investigate the magnetic phase transition in body-centered cubic (bcc) iron using the classical Heisenberg model parameterized with first principles calculations. We demonstrate that our framework leads to a significant speedup without compromising the accuracy and precision and facilitates the study of much larger systems than is possible with its serial counterpart.

  7. Infrared analysis of propagators and vertices of Yang-Mills theory in Landau and Coulomb gauge

    SciTech Connect

    Schleifenbaum, W.; Leder, M.; Reinhardt, H.

    2006-06-15

    The infrared behavior of gluon and ghost propagators, ghost-gluon vertex, and three-gluon vertex is investigated for both the covariant Landau and the noncovariant Coulomb gauge. Assuming infrared ghost dominance, we find a unique infrared exponent in the d=4 Landau gauge, while in the d=3+1 Coulomb gauge we find two different infrared exponents. We also show that a finite dressing of the ghost-gluon vertex has no influence on the infrared exponents. Finally, we determine the infrared behavior of the three-gluon vertex analytically and calculate it numerically at the symmetric point in the Coulomb gauge.

  8. Families of solutions to the generalized Ginzburg-Landau equation and structural transitions between them

    SciTech Connect

    Ovchinnikov, Yu. N.

    2013-09-15

    Solutions to the generalized Ginzburg-Landau equations for superconductors are obtained for a Ginzburg-Landau parameter {kappa} close to unity. The families of solutions with arbitrary number n of flux quanta in a unit cell are analyzed. It is shown that under certain conditions, a cascade of phase transitions between different structures in a magnetic field appears near T{sub c}. Algebraic equations are derived for determining the boundaries of coexistence of different phases on the (T, H{sub 0}) plane.

  9. Nonconventional odd-denominator fractional quantum Hall states in the second Landau level.

    PubMed

    Kumar, A; Csáthy, G A; Manfra, M J; Pfeiffer, L N; West, K W

    2010-12-10

    We report the observation of a new fractional quantum Hall state in the second Landau level of a two-dimensional electron gas at the Landau level filling factor ν=2+6/13. We find that the model of noninteracting composite fermions can explain the magnitude of gaps of the prominent 2+1/3 and 2+2/3 states. The same model fails, however, to account for the gaps of the 2+2/5 and the newly observed 2+6/13 states suggesting that these two states are of exotic origin. PMID:21231551

  10. Optical Emission Spectroscopy Study of Competing Phases of Electrons in the Second Landau Level.

    PubMed

    Levy, A L; Wurstbauer, U; Kuznetsova, Y Y; Pinczuk, A; Pfeiffer, L N; West, K W; Manfra, M J; Gardner, G C; Watson, J D

    2016-01-01

    Quantum phases of electrons in the filling factor range 2≤ν≤3 are probed by the weak optical emission from the partially populated second Landau level and spin wave measurements. Observations of optical emission include a multiplet of sharp peaks that exhibit a strong filling factor dependence. Spin wave measurements by resonant inelastic light scattering probe breaking of spin rotational invariance and are used to link this optical emission with collective phases of electrons. A remarkably rapid interplay between emission peak intensities manifests phase competition in the second Landau level. PMID:26799037

  11. Optical Emission Spectroscopy Study of Competing Phases of Electrons in the Second Landau Level

    NASA Astrophysics Data System (ADS)

    Levy, A. L.; Wurstbauer, U.; Kuznetsova, Y. Y.; Pinczuk, A.; Pfeiffer, L. N.; West, K. W.; Manfra, M. J.; Gardner, G. C.; Watson, J. D.

    2016-01-01

    Quantum phases of electrons in the filling factor range 2 ≤ν ≤3 are probed by the weak optical emission from the partially populated second Landau level and spin wave measurements. Observations of optical emission include a multiplet of sharp peaks that exhibit a strong filling factor dependence. Spin wave measurements by resonant inelastic light scattering probe breaking of spin rotational invariance and are used to link this optical emission with collective phases of electrons. A remarkably rapid interplay between emission peak intensities manifests phase competition in the second Landau level.

  12. Landau quantization for a neutral particle in the presence of topological defects

    SciTech Connect

    Bakke, K.; Ribeiro, L. R.; Furtado, C.; Nascimento, J. R.

    2009-01-15

    In this paper we study the Landau levels in the nonrelativistic dynamics of a neutral particle which possesses a permanent magnetic dipole moment interacting with an external electric field in the curved space-time background with the presence or absence of a torsion field. The eigenfunction and eigenvalues of the Hamiltonian are obtained. We show that the presence of the topological defect breaks the infinite degeneracy of the Landau levels arising in this system. We also apply a duality transformation to discuss this same quantization for a dynamics of a neutral particle with a permanent electric dipole moment.

  13. Analytically solvable two-level quantum systems and Landau-Zener interferometry

    NASA Astrophysics Data System (ADS)

    Barnes, Edwin

    2013-07-01

    A simple algorithm is presented based on a type of partial reverse engineering that generates an unlimited number of exact analytical solutions to the Schrödinger equation for a general time-dependent two-level Hamiltonian. I demonstrate this method by deriving exact solutions corresponding to fast control pulses that contain arbitrarily many tunable parameters. It is shown that the formalism is naturally suited to generating analytical control protocols that perform precise nonadiabatic rapid passage and Landau-Zener interferometry near the quantum speed limit. A general, exact formula for Landau-Zener interference patterns is derived.

  14. The question of the realizability of the Landau scenario for the development of turbulence

    NASA Astrophysics Data System (ADS)

    Glyzin, S. D.; Kolesov, A. Yu.; Rozov, N. Kh.

    2009-02-01

    We suggest a phenomenological model for the development of turbulence in the form of the nonlinear Klein-Gordon equation perturbed by nonconservative disturbances. Combining analytic and numerical methods, we establish that the transition to turbulence in this equation can follow both the Landau and the Landau-Sell scenarios. As is known, the first scenario is related to a cascade of bifurcations of stable invariant tori of increasing dimensions. The other scenario is related to a chaotic attractor whose Lyapunov dimension increases indefinitely under variation of a certain control parameter.

  15. Restoring detailed balance in the Landau-Teller probabilities for collision-induced vibrational transitions.

    PubMed

    Nikitin, E E; Troe, J

    2006-05-01

    The general quasi-classical treatment for collision-induced vibrational transitions in diatomic molecules, under near-adiabatic conditions, is used to derive quantum corrections for probabilities, calculated in the external field approximation originally used by Landau and Teller. The quantum corrections are expressed through the Landau-Teller classical collision time. The first-order correction to the classical exponent restores detailed balance for up- and down-transitions and does not depend on the properties of the bath except for its temperature. The limits of applicability of the first-order correction are discussed. PMID:16633688

  16. Poincaré-like approach to Landau theory. I. General theory

    NASA Astrophysics Data System (ADS)

    Gaeta, Giuseppe

    2015-08-01

    We discuss a procedure to simplify the Landau potential, based on Michel's reduction to orbit space and Poincaré normalization procedure, and illustrate it by concrete examples. The method makes use, as in Poincaré theory, of a chain of near-identity coordinate transformations with homogeneous generating functions; using Michel's insight, one can work in orbit space. It is shown that it is possible to control the choice of generating functions so to obtain a (in many cases, substantial) simplification of the Landau polynomial, including a reduction of the parameters it depends on. Several examples are considered in detail.

  17. Landau-Lifshitz-Gilbert equation with symmetric coefficients of the dissipative function II

    NASA Astrophysics Data System (ADS)

    Salazar, M.; Pérez Alcazar, G. A.

    2016-07-01

    In a previous study (Salazar and Perez Alcazar, 2015) we obtained the modified Landau-Lifshitz-Gilbert equation. The modification consisted in proposing a method to convert to symmetrical the kinetic coefficients of this equation. In the present study we find the solution to the proposed equation. This solution shows that the Mx and My components of the magnetization have damped oscillations. We find the expressions for the damping coefficient and the frequency of the oscillations and show their graphs. Finally, we compare these graphs with those that correspond to the frequency of oscillations for the magnetization in the Landau-Lifshitz-Gilbert equation.

  18. Equivalences Between GIT Quotients of Landau-Ginzburg B-Models

    NASA Astrophysics Data System (ADS)

    Segal, Ed

    2011-06-01

    We define the category of B-branes in a (not necessarily affine) Landau-Ginzburg B-model, incorporating the notion of R-charge. Our definition is a direct generalization of the category of perfect complexes. We then consider pairs of Landau-Ginzburg B-models that arise as different GIT quotients of a vector space by a one-dimensional torus, and show that for each such pair the two categories of B-branes are quasi-equivalent. In fact we produce a whole set of quasi-equivalences indexed by the integers, and show that the resulting auto-equivalences are all spherical twists.

  19. Landau-Ginzburg to Calabi-Yau dictionary for D-branes

    SciTech Connect

    Aspinwall, Paul S.

    2007-08-15

    Based on the work by Orlov (e-print arXiv:math.AG/0503632), we give a precise recipe for mapping between B-type D-branes in a Landau-Ginzburg orbifold model (or Gepner model) and the corresponding large radius Calabi-Yau manifold. The D-branes in Landau-Ginzburg theories correspond to matrix factorizations and the D-branes on the Calabi-Yau manifolds are objects in the derived category. We give several examples including branes on quotient singularities associated with weighted projective spaces. We are able to confirm several conjectures and statements in the literature.

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

    SciTech Connect

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

    2011-03-15

    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.

  1. Landau Zener scenario in a trapped atomic gas: multi-level multi-particle model

    NASA Astrophysics Data System (ADS)

    Fai, Lukong Cornelius; Tchoffo, Martin; Jipdi, Michael Nana

    2015-07-01

    The paper investigates multi-level and multi-particle Landau-Zener problem applying the dynamic matrix approach. The Landau Zener transitions are observed to depend sensitively on the frequency, phase of interaction and number of levels and particles. The dynamic behaviour of atomic trapped gas is solved for one particle model that permits to deduce different probabilities for particular initial conditions. The generalization of the probabilities permits to solve any multi-level system with an arbitrary number of particles and controlled particle transitions.

  2. Four-state nonstationary models in multistate Landau-Zener theory

    SciTech Connect

    Ostrovsky, V. N.; Volkov, M. V.; Hansen, J. P.; Selstoe, S.

    2007-01-01

    A dynamic four-state system is considered within the context of multistate Landau-Zener theory. It is shown that the theory accounts very well for the time-dependent state populations and final transition probabilities even in cases when multiple crossings appear in close vicinity of each other. This is also true for multiple paths systems when the phases are appropriately accounted for. It is found that transitions may take place also between diabatic states that do not couple directly and that the dynamics of such crossings may be accurately described within the multichannel Landau-Zener theory.

  3. Landau-Zener transitions in a multilevel system: An exact result

    SciTech Connect

    Shytov, A.V.

    2004-11-01

    We study the S matrix for the transitions at an avoided crossing of several energy levels, which is a multilevel generalization of the Landau-Zener problem. We demonstrate that, by extending the Schroedinger evolution to complex time, one can obtain an exact answer for some of the transition amplitudes. Similar to the Landau-Zener case, our result covers both the adiabatic (slow evolution) and the diabatic (fast evolution) regimes. The form of the exact transition amplitude coincides with that obtained in a sequential pairwise level crossing approximation, in accord with the conjecture of Brundobler and Elser [J. Phys. A 26, 1211 (1993)].

  4. Time-Resolved Measurement of Landau-Zener Tunneling in Periodic Potentials

    SciTech Connect

    Zenesini, A.; Radogostowicz, J.; Ciampini, D.; Mannella, R.; Arimondo, E.; Lignier, H.; Morsch, O.; Tayebirad, G.; Wimberger, S.

    2009-08-28

    We report time-resolved measurements of Landau-Zener tunneling of Bose-Einstein condensates in accelerated optical lattices, clearly resolving the steplike time dependence of the band populations. Using different experimental protocols we were able to measure the tunneling probability both in the adiabatic and in the diabatic bases of the system. We also experimentally determine the contribution of the momentum width of the Bose condensates to the temporal width of the tunneling steps and discuss the implications for measuring the jump time in the Landau-Zener problem.

  5. Multi-crossing problem and Landau Zener scenario: controlled quantum bit

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    The paper investigates multi-crossing dynamics of two-level Landau Zener (LZ) systems applying Dynamic matrix approach (DMA) and shows the two-level (multi-crossing) model to tailor qubits. The paper derives the probabilities for different multi-crossing problems and finds the possible parameters tailoring qubits. Particulary we investigate a variant of the Landau-Zener problem in which the coupling between the adiabatic levels is induced by an ac field, i.e., the energy level or tunnel coupling oscillates. We consider two limits, namely fast and slow driving in which the transition probability found exact analytical solution and derive the resonance condition for frequencies.

  6. Radial symmetry on three-dimensional shells in the Landau-de Gennes theory

    NASA Astrophysics Data System (ADS)

    Canevari, Giacomo; Ramaswamy, Mythily; Majumdar, Apala

    2016-01-01

    We study the radial-hedgehog solution on a three-dimensional (3D) spherical shell with radial boundary conditions, within the Landau-de Gennes theory for nematic liquid crystals. We prove that the radial-hedgehog solution is the unique minimizer of the Landau-de Gennes energy in two separate regimes: (i) for thin shells when the temperature is below the critical nematic supercooling temperature and (ii) for a fixed shell width at sufficiently low temperatures. In case (i), we provide explicit geometry-dependent criteria for the global minimality of the radial-hedgehog solution.

  7. Exact solution of the Landau-Lifshitz equations for a radiating charged particle in the Coulomb potential

    SciTech Connect

    Rajeev, S.G.

    2008-11-15

    We solve exactly the classical non-relativistic Landau-Lifshitz equations of motion for a charged particle moving in a Coulomb potential, including radiation damping. The general solution involves the Painleve transcendent of type II. It confirms our physical intuition that a negatively charged classical particle will spiral into the nucleus, supporting the validity of the Landau-Lifshitz equation.

  8. Parallel solution of the three-dimensional time-dependent Ginzburg- Landau equation

    SciTech Connect

    Galbreath, N.; Gropp, W.; Gunter, D.; Leaf, G.; Levine, D.

    1996-08-01

    The recent discovery of superconductivity in a class of copper-oxide compounds (the cuprate superconductors) at liquid nitrogen temperatures has generated a renewed interest in the magnetic properties of type-II superconductors. In our work, we are investigating these properties using the phenomenological time- dependent Ginzburg-Landau equation. This paper describes the parallelization of this equation.

  9. Gluon and ghost propagators in the Landau gauge: Deriving lattice results from Schwinger-Dyson equations

    SciTech Connect

    Aguilar, A. C.; Papavassiliou, J.; Binosi, D.

    2008-07-15

    We show that the application of a novel gauge-invariant truncation scheme to the Schwinger-Dyson equations of QCD leads, in the Landau gauge, to an infrared finite gluon propagator and a divergent ghost propagator, in qualitative agreement with recent lattice data.

  10. Landau level quantization and almost flat modes in three-dimensional semimetals with nodal ring spectra

    NASA Astrophysics Data System (ADS)

    Rhim, Jun-Won; Kim, Yong Baek; Canadian Institute for Advanced Research Collaboration

    We investigate Landau level structures of semimetals with nodal ring dispersions. When the magnetic field is applied parallel to the plane in which the ring lies, there exist almost nondispersive Landau levels at the Fermi level (EF = 0) as a function of the momentum along the field direction inside the ring. We show that the Landau levels at each momentum along the field direction can be described by the Hamiltonian for the graphene bilayer with fictitious interlayer couplings under a tilted magnetic field. Near the center of the ring where the interlayer coupling is negligible, we have Dirac Landau levels which explain the appearance of the zero modes. Although the interlayer hopping amplitudes become finite at higher momenta, the splitting of zero modes is exponentially small and they remain almost flat due to the finite artificial in-plane component of the magnetic field. The emergence of the density of states peak at the Fermi level would be a hallmark of the ring dispersion.

  11. Landau level quantization and almost flat modes in three-dimensional semimetals with nodal ring spectra

    NASA Astrophysics Data System (ADS)

    Rhim, Jun-Won; Kim, Yong Baek

    2015-07-01

    We investigate Landau level structures of semimetals with nodal ring dispersions. When the magnetic field is applied parallel to the plane in which the ring lies, there exist almost nondispersive Landau levels at the Fermi level (EF=0 ) as a function of the momentum along the field direction inside the ring. We show that the Landau levels at each momentum along the field direction can be described by the Hamiltonian for the graphene bilayer with fictitious interlayer couplings under a tilted magnetic field. Near the center of the ring where the in-terlayer coupling is negligible, we have Dirac Landau levels which explain the appearance of the zero modes. Although the interlayer hopping amplitudes become finite at higher momenta, the splitting of zero modes is exponentially small and they remain almost flat due to the finite artificial in-plane component of the magnetic field. The emergence of the density of states peak at the Fermi level would be a hallmark of the ring dispersion.

  12. Landau Damping in Sobolev Spaces for the Vlasov-HMF Model

    NASA Astrophysics Data System (ADS)

    Faou, Erwan; Rousset, Frédéric

    2016-02-01

    We consider the Vlasov-HMF (Hamiltonian Mean-Field) model. We consider solutions starting in a small Sobolev neighborhood of a spatially homogeneous state satisfying a linearized stability criterion (Penrose criterion). We prove that these solutions exhibit a scattering behavior to a modified state, which implies a nonlinear Landau damping effect with polynomial rate of damping.

  13. Non-equilibrium dynamics of the complex Ginzburg-Landau equation

    NASA Astrophysics Data System (ADS)

    Liu, Weigang; Tauber, Uwe

    The complex Ginzburg-Landau equation combines the quantum many-particle nonlinear Schrödinger equation with the time-dependent Ginzburg-Landau equation or model A relaxational dynamics. It arises in quite diverse contexts that include spontaneous pattern formation out of equilibrium, chemical oscillations, multi-mode lasers, thermal convection in binary fluids, cyclic population dynamics, and driven-dissipative Bose-Einstein condensates. Indeed, the complex Ginzburg-Landau equation exhibits a remarkably rich phase diagram with intriguing dynamics. We employ detailed numerical studies as well as analytical tools such as the perturbative renormalization group and the spherical model limit to study the non-equilibrium coarsening and critical aging scaling for the complex Ginzburg-Landau equation following quenches from an initial disordered configuration to either one of the ordered phases or the critical point. This research is supported by the U. S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Science and Engineering under Award DE-FG02-09ER46613.

  14. Ginzburg-Landau theory for skyrmions in inversion-symmetric magnets with competing interactions

    DOE PAGESBeta

    Lin, Shi-Zeng; Hayami, Satoru

    2016-02-01

    Magnetic skyrmions have attracted considerable attention recently for their huge potential in spintronic applications. Generally skyrmions are big compared to the atomic lattice constant, which allows for the Ginzburg-Landau type description in the continuum limit. This description successfully captures the main experimental observations on skyrmions in B20 compound without inversion symmetry. Skyrmions can also exist in inversion-symmetric magnets with competing interactions. Here, we derive a general Ginzburg-Landau theory for skyrmions in these magnets valid in the long-wavelength limit. We study the unusual static and dynamical properties of skyrmions based on the derived Ginzburg-Landau theory. We show that an easy axismore » spin anisotropy is sufficient to stabilize a skyrmion lattice. Interestingly, the skyrmion in inversion-symmetric magnets has a new internal degree of freedom associated with the rotation of helicity, i.e., the “spin” of the skyrmion as a particle, in addition to the usual translational motion of skyrmions (orbital motion). The orbital and spin degree of freedoms of an individual skyrmion can couple to each other, and give rise to unusual behavior that is absent for the skyrmions stabilized by the Dzyaloshinskii-Moriya interaction. Finally, the derived Ginzburg-Landau theory provides a convenient and general framework to discuss skyrmion physics and will facilitate the search for skyrmions in inversion-symmetric magnets.« less

  15. An introduction to the Ginzburg-Landau theory of phase transitions and nonequilibrium patterns

    NASA Astrophysics Data System (ADS)

    Hohenberg, P. C.; Krekhov, A. P.

    2015-04-01

    This paper presents an introduction to phase transitions and critical phenomena on the one hand, and nonequilibrium patterns on the other, using the Ginzburg-Landau theory as a unified language. In the first part, mean-field theory is presented, for both statics and dynamics, and its validity tested self-consistently. As is well known, the mean-field approximation breaks down below four spatial dimensions, where it can be replaced by a scaling phenomenology. The Ginzburg-Landau formalism can then be used to justify the phenomenological theory using the renormalization group, which elucidates the physical and mathematical mechanism for universality. In the second part of the paper it is shown how near pattern forming linear instabilities of dynamical systems, a formally similar Ginzburg-Landau theory can be derived for nonequilibrium macroscopic phenomena. The real and complex Ginzburg-Landau equations thus obtained yield nontrivial solutions of the original dynamical system, valid near the linear instability. Examples of such solutions are plane waves, defects such as dislocations or spirals, and states of temporal or spatiotemporal (extensive) chaos.

  16. Landau levels of cold dense quark matter in a strong magnetic field

    NASA Astrophysics Data System (ADS)

    Wen, Xin-Jian; Liang, Jun-Jun

    2016-07-01

    The occupied Landau levels of strange quark matter are investigated in the framework of the SU(3) NJL model with a conventional coupling and a magnetic-field dependent coupling respectively. At lower density, the Landau levels are mainly dominated by u and d quarks. Threshold values of the chemical potential for the s quark onset are shown in the μ -B plane. The magnetic-field-dependent running coupling can broaden the region of three-flavor matter by decreasing the dynamical masses of s quarks. Before the onset of s quarks, the Landau level number of light quarks is directly dependent on the magnetic field strength B by a simple inverse proportional relation ki ,max≈Bi0/B with Bd0=5 ×1 019 G , which is approximately 2 times Bu0 of u quarks at a common chemical potential. When the magnetic field increases up to Bd0, almost all three flavors are lying in the lowest Landau level.

  17. Relativistic Landau-Aharonov-Casher quantization based on the Lorentz symmetry violation background

    SciTech Connect

    Bakke, K.; Belich, H.; Silva, E. O.

    2011-06-15

    Based on the discussions about the Aharonov-Casher effect in the Lorentz symmetry violation background, we show that the analogue of the relativistic Landau quantization in the Aharonov-Casher setup can be achieved in the Lorentz-symmetry violation background.

  18. Acquired aphasia without deafness in childhood--the Landau-Kleffner syndrome.

    PubMed

    Hughes, A P; Appleton, R E; Hodgson, J

    1993-07-01

    A young boy presented with loss of speech and behaviour disturbance and was thought to be deaf. He was subsequently found to have the Landau-Kleffner syndrome (LKS), or acquired aphasia with epilepsy. Children with this disorder commonly present to an audiology or ENT clinic. Early recognition is important to initiate supportive, speech and educational care. PMID:15125283

  19. Analysis of a coupled spin drift-diffusion Maxwell-Landau-Lifshitz system

    NASA Astrophysics Data System (ADS)

    Zamponi, Nicola; Jüngel, Ansgar

    2016-05-01

    The existence of global weak solutions to a coupled spin drift-diffusion and Maxwell-Landau-Lifshitz system is proved. The equations are considered in a two-dimensional magnetic layer structure and are supplemented with Dirichlet-Neumann boundary conditions. The spin drift-diffusion model for the charge density and spin density vector is the diffusion limit of a spinorial Boltzmann equation for a vanishing spin polarization constant. The Maxwell-Landau-Lifshitz system consists of the time-dependent Maxwell equations for the electric and magnetic fields and of the Landau-Lifshitz-Gilbert equation for the local magnetization, involving the interaction between magnetization and spin density vector. The existence proof is based on a regularization procedure, L2-type estimates, and Moser-type iterations which yield the boundedness of the charge and spin densities. Furthermore, the free energy is shown to be nonincreasing in time if the magnetization-spin interaction constant in the Landau-Lifshitz equation is sufficiently small.

  20. Ginzburg-Landau theory for skyrmions in inversion-symmetric magnets with competing interactions

    NASA Astrophysics Data System (ADS)

    Lin, Shi-Zeng; Hayami, Satoru

    2016-02-01

    Magnetic skyrmions have attracted considerable attention recently for their huge potential in spintronic applications. Generally skyrmions are big compared to the atomic lattice constant, which allows for the Ginzburg-Landau type description in the continuum limit. Such a description successfully captures the main experimental observations on skyrmions in B20 compound without inversion symmetry. Skyrmions can also exist in inversion-symmetric magnets with competing interactions. Here, we derive a general Ginzburg-Landau theory for skyrmions in these magnets valid in the long-wavelength limit. We study the unusual static and dynamical properties of skyrmions based on the derived Ginzburg-Landau theory. We show that an easy axis spin anisotropy is sufficient to stabilize a skyrmion lattice. Interestingly, the skyrmion in inversion-symmetric magnets has a new internal degree of freedom associated with the rotation of helicity, i.e., the "spin" of the skyrmion as a particle, in addition to the usual translational motion of skyrmions (orbital motion). The orbital and spin degree of freedoms of an individual skyrmion can couple to each other, and give rise to unusual behavior that is absent for the skyrmions stabilized by the Dzyaloshinskii-Moriya interaction. The derived Ginzburg-Landau theory provides a convenient and general framework to discuss skyrmion physics and will facilitate the search for skyrmions in inversion-symmetric magnets.

  1. Landau damping in the improved SLC linac: A, The sensitivity to injection jitter

    SciTech Connect

    Bane, K.L.F.

    1988-04-01

    In this report we study the effects of injection jitter on emittance growth, and hence on luminosity, in the improved linac with stronger focusing, and for the new bunch parameters. We consider both cases when Landau damping has been invoked, and when it has not been.

  2. Development of electromagnetic cascades in the atmosphere including the Landau-Pomeranchuk-Migdal effect

    NASA Technical Reports Server (NTRS)

    Streitmatter, R. E.; Stephens, S. A.

    1985-01-01

    Numerical solutions have been obtained for the one-dimensional atmospheric electromagnetic cascade diffusion equations, including the Landau-Pomeranchuk-Migdal and screening effects. Spectra produced by primary gamma rays of various energies are given at a number of deths in the atmosphere.

  3. The first radial-mode Lorentzian Landau damping of dust acoustic space-charge waves

    NASA Astrophysics Data System (ADS)

    Lee, Myoung-Jae; Jung, Young-Dae

    2016-05-01

    The dispersion properties and the first radial-mode Lorentzian Landau damping of a dust acoustic space-charge wave propagating in a cylindrical waveguide dusty plasma which contains nonthermal electrons and ions are investigated by employing the normal mode analysis and the method of separation of variables. It is found that the frequency of dust acoustic space-charge wave increases as the wave number increases as well as the radius of cylindrical plasma does. However, the nonthermal property of the Lorentzian plasma is found to suppress the wave frequency of the dust acoustic space-charge wave. The Landau damping rate of the dust acoustic space-charge wave is derived in a cylindrical waveguide dusty plasma. The damping of the space-charge wave is found to be enhanced as the radius of cylindrical plasma and the nonthermal property increase. The maximum Lorentzian Landau damping rate is also found in a cylindrical waveguide dusty plasma. The variation of the wave frequency and the Landau damping rate due to the nonthermal character and geometric effects are also discussed.

  4. Testing the Ginzburg-Landau approximation for three-flavor crystalline color superconductivity

    NASA Astrophysics Data System (ADS)

    Mannarelli, Massimo; Rajagopal, Krishna; Sharma, Rishi

    2006-06-01

    It is an open challenge to analyze the crystalline color superconducting phases that may arise in cold dense, but not asymptotically dense, three-flavor quark matter. At present the only approximation within which it seems possible to compare the free energies of the myriad possible crystal structures is the Ginzburg-Landau approximation. Here, we test this approximation on a particularly simple “crystal” structure in which there are only two condensates ⟨us⟩˜Δexp⁡(iq2·r) and ⟨ud⟩˜Δexp⁡(iq3·r) whose position-space dependence is that of two plane waves with wave vectors q2 and q3 at arbitrary angles. For this case, we are able to solve the mean-field gap equation without making a Ginzburg-Landau approximation. We find that the Ginzburg-Landau approximation works in the Δ→0 limit as expected, find that it correctly predicts that Δ decreases with increasing angle between q2 and q3 meaning that the phase with q2∥q3 has the lowest free energy, and find that the Ginzburg-Landau approximation is conservative in the sense that it underestimates Δ at all values of the angle between q2 and q3.

  5. Influence of the Landau-Pomeranchuk-Migdal effect on the features of extensive air showers

    SciTech Connect

    Kalmykov, N.N.; Ostapchenko, S.S.; Pavlov, A.I.

    1995-10-01

    The influence of the Landau-Pomeranchuk-Migdal (LPM) effect on the features of extensive air showers (EAS) is studied. The development of hadronic cascades is described in the quark-gluon string model. It is shown that the LPM effect does not exert a significant influence on EAS features up to energies of 10{sup 20} eV. 19 refs., 2 figs.

  6. Acceleration of soliton by nonlinear Landau damping of dust-helical waves

    SciTech Connect

    Ehsan, Zahida; Tsintsadze, Nodar L.; Vranjes, J.; Poedts, S.

    2009-05-15

    The problem of nonlinear Landau damping of helicon waves in dusty plasma in particular emphasis to the acceleration of soliton is presented here. This in the framework of a collisionless, anisotropic homogeneous dusty plasma in one dimension, can be well described by two coupled dynamical equations of the generalized Zakharov type, with one extra nonlocal term coming from Landau damping. Nonlinear-nonlocal term gives rise to essential contributions relative to the local term. Then under different conditions, kinetic nonlinear Schroedinger equation is constructed and nonlinear decrement is obtained for two cases. It is noticed that the time dependant term in the ponderomotive force plays a significant role for this kind of damping. Additionally, it is shown that nonlinear Landau damping leads to the amplitude modulation of dust helicon waves, further modulational instability, and maximal growth rate is obtained when the group velocity of the helicon wave reaches the dust-acoustic speed. It is demonstrated that how the nonlinear Landau damping leads to the acceleration of soliton, which is eventually slowed down after transferring some of its energy to the wave. Emission of dust-acoustic wave by accelerated soliton is discussed briefly.

  7. Landau-Zener tunneling of Bose-Einstein condensates in an optical lattice

    SciTech Connect

    Konotop, V.V.; Kevrekidis, P.G.; Salerno, M.

    2005-08-15

    A theory of the nonsymmetric Landau-Zener tunneling of Bose-Einstein condensates in deep optical lattices is presented. It is shown that periodic exchange of matter between the bands is described by a set of linearly coupled nonlinear Schroedinger equations. The key role of the modulational instability in rendering the interband transitions irreversible is highlighted.

  8. The dynamics of scroll wave filaments in the complex Ginzburg-Landau equation

    NASA Astrophysics Data System (ADS)

    Gabbay, Michael; Ott, Edward; Guzdar, Parvez N.

    1998-07-01

    An analytical treatment is presented for scroll waves in the complex Ginzburg-Landau equation in the limit of small filament curvature, torsion, and phase twist. Explicit expressions for the filament velocity and frequency shift are found. The theoretical results are verified numerically in the case of circular untwisted scroll rings and for straight and sinusoidal scroll filaments with phase twist.

  9. Motion of Scroll Wave Filaments in the Complex Ginzburg-Landau Equation

    NASA Astrophysics Data System (ADS)

    Gabbay, Michael; Ott, Edward; Guzdar, Parvez N.

    1997-03-01

    Explicit asymptotic analytical results are derived for the motion of scroll wave filaments in the complex Ginzburg-Landau equation. Good agreement with numerical tests is obtained. The analysis highlights the necessity of allowing for previously ignored small wave-number shifts in the propagation of the waves away from the filament.

  10. Competing quantum Hall phases in the second Landau level in low density limit

    NASA Astrophysics Data System (ADS)

    Pan, Wei; Serafin, A.; Xia, J. S.; Yin, L.; Sullivan, N. S.; Baldwin, K. W.; West, K. W.; Pfeiffer, L. N.; Tsui, D. C.

    2015-03-01

    We present here the results from two high quality, low density GaAs quantum wells. In sample A of electron density n = 5.0 x 1010 cm-2, anisotropic electronic transport behavior was observed at ν = 7/2 in the second Landau level. We believe that the anisotropy is due to the large Landau level mixing effect in this sample. In sample B of density 4.1 x 1010 cm-2, strong 8/3, 5/2, and 7/3 fractional quantum Hall states were observed. Furthermore, our energy gap data obtained in various samples of different densities suggest that the 5/2 state may be spin unpolarized in the low density limit. The results from both samples show that the strong electron-electron interactions and a large Landau level mixing effect play an import role in the competing ground states in the second landau level. 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-AC04-94AL85000. This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division.

  11. Spontaneous polarization of composite fermions in the n =1 Landau level of graphene

    NASA Astrophysics Data System (ADS)

    Balram, Ajit C.; Tőke, Csaba; Wójs, A.; Jain, J. K.

    2015-11-01

    Motivated by recent experiments that reveal expansive fractional quantum Hall states in the n =1 graphene Landau level and suggest a nontrivial role of the spin degree of freedom [31 F. Amet, A. J. Bestwick, J. R. Williams, L. Balicas, K. Watanabe, T. Taniguchi, and D. Goldhaber-Gordon, Nat. Commun. 6, 5838 (2015), 10.1038/ncomms6838], we perform an accurate quantitative study of the competition between fractional quantum Hall states with different spin polarizations in the n =1 graphene Landau level. We find that the fractional quantum Hall effect is well described in terms of composite fermions, but the spin physics is qualitatively different from that in the n =0 Landau level. In particular, for the states at filling factors ν =s /(2 s ±1 ) , s positive integer, a combination of exact diagonalization and the composite fermion theory shows that the ground state is fully spin polarized and supports a robust spin-wave mode even in the limit of vanishing Zeeman coupling. Thus, even though composite fermions are formed, a mean-field description that treats them as weakly interacting particles breaks down, and the exchange interaction between them is strong enough to cause a qualitative change in the behavior by inducing full spin polarization. We also verify that the fully spin-polarized composite fermion Fermi sea has lower energy than the paired Pfaffian state at the relevant half fillings in the n =1 graphene Landau level, indicating an absence of composite fermion pairing at half filling in the n =1 graphene Landau level.

  12. Der Physik-Nobelpreis vor 100 Jahren Eine neue Eigenschaft der Materie

    NASA Astrophysics Data System (ADS)

    Jacobi, Manfred

    2003-11-01

    Im Jahre 1903 erhielten Henri Becquerel sowie Marie und Pierre Curie den Physik-Nobelpreis für die Entdeckung der Radioaktivität. Schon damals stellte Pierre Curie die Frage nach Nutzen und Gefahr dieser neuen Eigenschaft von Materie. Er war der Überzeugung, dass der Fortschritt letztlich mehr zum Nutzen als zum Schaden der Menschen beitrage.

  13. Physik gestern und heute Der Spion, der die Wärme untersuchte

    NASA Astrophysics Data System (ADS)

    Heering, Peter

    2003-11-01

    Der in Massachusetts geborene Benjamin Thompson, der ab 1792 auch den Titel eines Grafen von Rumford führte, ist eine der schillerndsten Figuren der Physikgeschichte. Berühmt wurde er insbesondere wegen seiner Experimente zur Wärmetheorie.http://www.famousamericans.net/benjaminthompsonrumford

  14. Formation of van der Waals molecules in buffer-gas-cooled magnetic traps [corrected].

    PubMed

    Brahms, N; Tscherbul, T V; Zhang, P; Kłos, J; Sadeghpour, H R; Dalgarno, A; Doyle, J M; Walker, T G

    2010-07-16

    We predict that a large class of helium-containing cold polar molecules form readily in a cryogenic buffer gas, achieving densities as high as 10(12)  cm(-3). We explore the spin relaxation of these molecules in buffer-gas-loaded magnetic traps and identify a loss mechanism based on Landau-Zener transitions arising from the anisotropic hyperfine interaction. Our results show that the recently observed strong T(-6) thermal dependence of the spin-change rate of silver (Ag) trapped in dense (3)He is accounted for by the formation and spin change of Ag(3)He van der Waals molecules, thus providing indirect evidence for molecular formation in a buffer-gas trap. PMID:20867761

  15. Coronellis Cosmos in der Melker Stiftsbibliothek.

    NASA Astrophysics Data System (ADS)

    Glaßner, Gottfried; Pärr, Nora

    2009-06-01

    Die Melker Stiftsbibliothek besitzt ein Globenpaar des berühmten venezianischen Globenbauers Vincenzo Coronelli (1650-1718), einen Erdglobus von 1688 und einen Himmelsglobus von 1693. Wie und wann die beiden Globen nach Melk gekommen sind, ist nicht bekannt. Dass sie zur ursprünglichen Ausstattung der 1735 fertig gestellten Barockbibliothek gehörten, wird aber aus der zentralen Stellung deutlich, die dem Globus (Erdglobus und Armillarphäre) in dem von Paul Troger 1732 gemalten Deckenfresko zukommt. Mehrfach begegnet das Motiv des Globus als Attribut der Weisheit bzw. Philosophie, der Geographie bzw. Geometrie und der Astronomie in den beiden Hauptsälen wie auch in der Deckenmalerei von Johann Bergl in der Oberen Bibliothek (1768) und in der Kuppel des Gartenpavillons (1764).

  16. Historisches Rätsel Der rastlose Amerikaner

    NASA Astrophysics Data System (ADS)

    Loos, Andreas

    2004-09-01

    In der Schule, die er mit acht Jahren zum ersten Mal von innen sah, hielt man ihn nicht für allzu helle - schließlich hinkte der Kleine oft hinter der Klasse her. Und es hat etwas Tragisches, wenn der wohl berühmteste Erfinder aller Zeiten und Halter von 2000 Patenten im Alter über seinen Vater sagt: Er dachte, ich sei dumm. Und ich meinte schon fast selbst, ich sei ein Dummkopf.

  17. [The 'van der Linden' retainer].

    PubMed

    van der Linden, F P

    2003-11-01

    Normally, only the anterior teeth have to be retained after an orthodontic treatment. For that purpose, a lingually bonded wire is preferred in the mandible and a removable plate in the maxilla. The design of the Van der Linden-retainer is based on theoretical considerations and secures rigid fixation of the six anterior teeth with solid anchorage in that region. A retention plate should not be used to move anterior teeth. However, with instant corrections small improvements can be realized. The fabrication and clinical use of the Van der Linden-retainer is explained and illustrated. PMID:14669487

  18. Attractivity of the Ginzburg-Landau mode distribution for a pattern forming system with marginally stable long modes

    NASA Astrophysics Data System (ADS)

    Düll, Wolf-Patrick; Kashani, Kourosh Sanei; Schneider, Guido; Zimmermann, Dominik

    2016-07-01

    The mathematical theory of the description of pattern forming systems close to the first instability via the Ginzburg-Landau equation is based on approximation and attractivity results. This theory allowed to prove global existence results and upper semicontinuity of attractors for classical hydrodynamical stability problems such as the Couette-Taylor problem. Recently, approximation results for the Ginzburg-Landau approximation for pattern forming systems with marginally stable long modes, such as the Bénard-Marangoni system, have been shown. It is the purpose of this paper to prove the second fundamental property, namely the attractivity of the Ginzburg-Landau mode distribution, for such systems.

  19. Surface acoustic BLOCH oscillations, the Wannier-Stark ladder, and Landau-Zener tunneling in a solid.

    PubMed

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

    2010-04-23

    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. PMID:20482064

  20. Der Begriff der Verständlichkeit in der modernen Physik (1948).

    PubMed

    Feyerabend, Paul K

    2016-06-01

    This is a critical transcription of Paul Feyerabend's earliest extant essay "Der Begriff der Verständlichkeit in der modernen Physik" (1948) recovered from the European Forum Alpbach archives. In it, Feyerabend defends positivism as a progressive framework for scientific research in certain stages of scientific development. He argues that in physics visualizability (Anschaulichkeit) and intelligibility (Verständlichkeit) are time-conditioned concepts: what is deemed visualizable in the development of physical theories is relative to a specific historical context and changes over time. He concludes that from time to time the abandonment of visualizability is crucial for progress in physics, as it is conducive to major theory change, illustrating the point on the basis of advances in atomic theory. PMID:27269264

  1. Ancillary Services Provided from DER

    SciTech Connect

    Campbell, J.B.

    2005-12-21

    Distributed energy resources (DER) are quickly making their way to industry primarily as backup generation. They are effective at starting and then producing full-load power within a few seconds. The distribution system is aging and transmission system development has not kept up with the growth in load and generation. The nation's transmission system is stressed with heavy power flows over long distances, and many areas are experiencing problems in providing the power quality needed to satisfy customers. Thus, a new market for DER is beginning to emerge. DER can alleviate the burden on the distribution system by providing ancillary services while providing a cost adjustment for the DER owner. This report describes 10 types of ancillary services that distributed generation (DG) can provide to the distribution system. Of these 10 services the feasibility, control strategy, effectiveness, and cost benefits are all analyzed as in the context of a future utility-power market. In this market, services will be provided at a local level that will benefit the customer, the distribution utility, and the transmission company.

  2. Direct path from microscopic mechanics to Debye shielding, Landau damping and wave-particle interaction

    NASA Astrophysics Data System (ADS)

    Escande, D. F.; Elskens, Yves; Doveil, F.

    2015-02-01

    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.

  3. Landau-Lifshitz magnetodynamics as a Hamilton model: Magnons in an instanton background

    NASA Astrophysics Data System (ADS)

    Ovchinnikov, Igor V.; Wang, Kang L.

    2010-07-01

    To take full advantage of the well-developed field-theoretic methods, Magnonics needs a yet-existing Lagrangian formulation. Here, we show that Landau-Lifshitz magnetodynamics is a member of the covariant-Schrödinger-equation family of Hamilton models and apply the covariant background method arriving at the Ginzburg-Landau Lagrangian formalism for magnons in an instanton background. Magnons appear to be nonrelativistic spinless bosons, which feel instantons as a gauge field and as a Bose condensate. Among the examples of the usefulness of the proposition is the recognition of the instanton-induced phase shifts in magnons as the Berry phase and the interpretation of the spin-transfer-torque generation as a ferromagnetic counterpart of the Josephson supercurrent.

  4. Landau Level Mixing in the ν = 0 Quantum Hall State of Graphene

    NASA Astrophysics Data System (ADS)

    Feshami, Braden; Fertig, Herbert

    The ν = 0 quantum Hall state in graphene has been the focus of many studies over the last several years. Recent experimental developments have allowed for the possibility of tuning the strength of the Zeeman interaction by tilting a graphene sample in the presence of an external magnetic field. Many of the theoretical frameworks for these systems involve projecting into the zeroth Landau level (LL) and specifying effective interaction parameters to simplify the calculation. We explore the effects of keeping a larger number of LLs, allowing for the possibility of Landau level mixing, within a self-consistent Hartree-Fock theory of the system. We include a SU(4) symmectric, Coulombic-like, interaction, and introduce microscopic on-site and nearest-neighbor interactions. Phase diagrams are constructed over a range of these two microscopic interaction strengths for different magnetic field strengths and Zeeman couplings. Supported by US-Israel BSF and the NSF.

  5. Adaptation of the Landau-Migdal quasiparticle pattern to strongly correlated Fermi systems

    SciTech Connect

    Khodel, V. A.; Clark, J. W.; Zverev, M. V.

    2011-09-15

    A quasiparticle pattern advanced in Landau's first article on Fermi-liquid theory is adapted to elucidate the properties of a class of strongly correlated Fermi systems characterized by a Lifshitz phase diagram featuring a quantum critical point (QCP) where the density of states diverges. The necessary condition for stability of the Landau Fermi-Liquid state is shown to break down in such systems, triggering a cascade of topological phase transitions that lead, without symmetry violation, to states with multi-connected Fermi surfaces. The end point of this evolution is found to be an exceptional state whose spectrum of single-particle excitations exhibits a completely flat portion at zero temperature. Analysis of the evolution of the temperature dependence of the single-particle spectrum yields results that provide a natural explanation of classical behavior of this class of Fermi systems in the QCP region.

  6. On the Shape of Meissner Solutions to a Limiting Form of Ginzburg-Landau Systems

    NASA Astrophysics Data System (ADS)

    Xiang, Xingfei

    2016-07-01

    In this paper we study a semilinear system involving the curl operator, which is a limiting form of the Ginzburg-Landau model for superconductors in R^3 for a large value of the Ginzburg-Landau parameter. We consider the locations of the maximum points of the magnitude of solutions, which are associated with the nucleation of instability of the Meissner state for superconductors when the applied magnetic field is increased in the transition between the Meissner state and the vortex state. For small penetration depth, we prove that the location is not only determined by the tangential component of the applied magnetic field, but also by the normal curvatures of the boundary in some directions. This improves the result obtained by Bates and Pan in Commun. Math. Phys. 276, 571-610 (2007). We also show that the solutions decay exponentially in the normal direction away from the boundary if the penetration depth is small.

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

    NASA Astrophysics Data System (ADS)

    Schlottmann, P.

    2016-05-01

    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.

  8. Periodic Landau gauge and quantum Hall effect in twisted bilayer graphene

    NASA Astrophysics Data System (ADS)

    Hasegawa, Yasumasa; Kohmoto, Mahito

    2013-09-01

    Energy versus magnetic field (Hofstadter butterfly diagram) in twisted bilayer graphene is studied theoretically. If we take the usual Landau gauge, we cannot take a finite periodicity even when the magnetic flux through a supercell is a rational number. We show that the periodic Landau gauge, which has the periodicity in one direction, makes it possible to obtain the Hofstadter butterfly diagram. Since a supercell can be large, magnetic flux through a supercell normalized by the flux quantum can be a fractional number with a small denominator, even when a magnetic field is not extremely strong. As a result, quantized Hall conductance can be a solution of the Diophantine equation which cannot be obtained by the approximation of the linearized energy dispersion near the Dirac points.

  9. Surface Landau levels and spin states in bismuth (111) ultrathin films

    NASA Astrophysics Data System (ADS)

    Du, Hongjian; Sun, Xia; Liu, Xiaogang; Wu, Xiaojun; Wang, Jufeng; Tian, Mingyang; Zhao, Aidi; Luo, Yi; Yang, Jinlong; Wang, Bing; Hou, J. G.

    2016-03-01

    The development of next-generation electronics is much dependent on the discovery of materials with exceptional surface-state spin and valley properties. Because of that, bismuth has attracted a renewed interest in recent years. However, despite extensive studies, the intrinsic electronic transport properties of Bi surfaces are largely undetermined due to the strong interference from the bulk. Here we report the unambiguous determination of the surface-state Landau levels in Bi (111) ultrathin films using scanning tunnelling microscopy under magnetic fields perpendicular to the surface. The Landau levels of the electron-like and the hole-like carriers are accurately characterized and well described by the band structure of the Bi (111) surface from density functional theory calculations. Some specific surface spin states with a large g-factor are identified. Our findings shed light on the exploiting surface-state properties of Bi for their applications in spintronics and valleytronics.

  10. Optical Signatures of Competing Quantum Phases in the Second Landau Level

    NASA Astrophysics Data System (ADS)

    Levy, Antonio; Wurstbauer, Ursula; Pinczuk, Aron; Watson, John; Gardner, Geoff; Manfra, Michael; West, Ken; Baldwin, Kirk; Pfeiffer, Loren

    2015-03-01

    The fractional quantum Hall states and anisotropic phases of electrons in the N =1 Landau Level (LL) have drawn considerable experimental focus in recent years. We report evidence that the competition and coexistence of these phases is probed directly by optical recombination from the partially populated N =1 LL at dilution refrigerator temperatures. Spectral bands that display striking dependence on perpendicular magnetic field in the full range 3>nu>2 are interpreted as linked to anisotropic phases. Optical recombination thus enables the monitoring of the evolution competing phases as the N =1 LL filling is changed. Remarkable changes in the optical recombination reveal that coexistence of distinct quantum phases has a marked dependence on filling of the N =1 LL. The signatures of anisotropic phases remain strong at filling factors of the FQHE. This is consistent with recent reports on anisotropic FQHE states in the second Landau level. Supported by Award NSF-DMR-1306976.

  11. Realization of optical bistability and multistability in Landau-quantized graphene

    NASA Astrophysics Data System (ADS)

    Hamedi, H. R.; Asadpour, S. H.

    2015-05-01

    The solution of input-output curves in an optical ring cavity containing Landau-quantized graphene is theoretically investigated taking the advantage of density-matrix method. It is found that under the action of strong magnetic and infrared laser fields, one can efficiently reduce the threshold of the onset of optical bistability (OB) at resonance condition. At non-resonance condition, we observed that graphene metamaterial can support the possibility to obtain optical multistability (OM), which is more practical in all-optical switching or coding elements. We present an analytical approach to elucidate our simulations. Due to very high infrared optical nonlinearity of graphene stemming from very unique and unusual properties of quantized Landau levels near the Dirac point, such controllability on OB and OM may provide new technological possibilities in solid state quantum information science.

  12. Bilayer graphene under pressure: Electron-hole symmetry breaking, valley Hall effect, and Landau levels

    NASA Astrophysics Data System (ADS)

    Munoz, F.; Collado, H. P. Ojeda; Usaj, Gonzalo; Sofo, Jorge O.; Balseiro, C. A.

    2016-06-01

    The electronic structure of bilayer graphene under pressure develops very interesting features with an enhancement of the trigonal warping and a splitting of the parabolic touching bands at the K point of the reciprocal space into four Dirac cones, one at K and three along the T symmetry lines. As pressure is increased, these cones separate in reciprocal space and in energy, breaking the electron-hole symmetry. Due to their energy separation, their opposite Berry curvature can be observed in valley Hall effect experiments and in the structure of the Landau levels. Based on the electronic structure obtained by density functional theory, we develop a low energy Hamiltonian that describes the effects of pressure on measurable quantities such as the Hall conductivity and the Landau levels of the system.

  13. Realization of optical bistability and multistability in Landau-quantized graphene

    SciTech Connect

    Hamedi, H. R.; Asadpour, S. H.

    2015-05-14

    The solution of input-output curves in an optical ring cavity containing Landau-quantized graphene is theoretically investigated taking the advantage of density-matrix method. It is found that under the action of strong magnetic and infrared laser fields, one can efficiently reduce the threshold of the onset of optical bistability (OB) at resonance condition. At non-resonance condition, we observed that graphene metamaterial can support the possibility to obtain optical multistability (OM), which is more practical in all-optical switching or coding elements. We present an analytical approach to elucidate our simulations. Due to very high infrared optical nonlinearity of graphene stemming from very unique and unusual properties of quantized Landau levels near the Dirac point, such controllability on OB and OM may provide new technological possibilities in solid state quantum information science.

  14. SU(3) Landau gauge gluon and ghost propagators using the logarithmic lattice gluon field definition

    SciTech Connect

    Ilgenfritz, Ernst-Michael; Menz, Christoph; Mueller-Preussker, Michael; Schiller, Arwed; Sternbeck, Andre

    2011-03-01

    We study the Landau gauge gluon and ghost propagators of SU(3) gauge theory, employing the logarithmic definition for the lattice gluon fields and implementing the corresponding form of the Faddeev-Popov matrix. This is necessary in order to consistently compare lattice data for the bare propagators with that of higher-loop numerical stochastic perturbation theory. In this paper we provide such a comparison, and introduce what is needed for an efficient lattice study. When comparing our data for the logarithmic definition to that of the standard lattice Landau gauge we clearly see the propagators to be multiplicatively related. The data of the associated ghost-gluon coupling matches up almost completely. For the explored lattice spacings and sizes discretization artifacts, finite size, and Gribov-copy effects are small. At weak coupling and large momentum, the bare propagators and the ghost-gluon coupling are seen to be approached by those of higher-order numerical stochastic perturbation theory.

  15. Solvable four-state Landau-Zener model of two interacting qubits with path interference

    NASA Astrophysics Data System (ADS)

    Sinitsyn, N. A.

    2015-11-01

    I identify a nontrivial four-state Landau-Zener model for which transition probabilities between any pair of diabatic states can be determined analytically and exactly. The model describes an experimentally accessible system of two interacting qubits, such as a localized state in a Dirac material with both valley and spin degrees of freedom or a singly charged quantum dot (QD) molecule with spin orbit coupling. Application of the linearly time-dependent magnetic field induces a sequence of quantum level crossings with possibility of interference of different trajectories in a semiclassical picture. I argue that this system satisfies the criteria of integrability in the multistate Landau-Zener theory, which allows one to derive explicit exact analytical expressions for the transition probability matrix. I also argue that this model is likely a special case of a larger class of solvable systems, and present a six-state generalization as an example.

  16. Cavity Optomechanics with synthetic Landau levels of ultra cold Fermi gas

    NASA Astrophysics Data System (ADS)

    Ghosh, Sankalpa; Padhi, Bikash

    2014-03-01

    Ultra cold fermionic atoms placed in a synthetic magnetic field arrange themselves in Landau levels. We theoretically study the optomechanical interaction between the light field and collective excitations of such fermionic atoms in synthetic magnetic field by placing them in side a Fabry Perot cavity. We derive the effective hamiltonian for particle hole excitations from a filled Landau level using a bosonization technique and obtain an expression for the cavity transmission spectrum. Using this we show that the cavity transmission spectrum demonstrates cold atom analogue of Subnikov de Hass oscillation in electronic condensed matter systems. We discuss the experimental consequences for this oscillation for such system and the related optical bistability. Ref. Bikash Padhi and Sankalpa Ghosh, Physical Review Letters, Vol 111, 043603 (2013) PDA Grant, Indian Institute of Technology, Delhi.

  17. Spin-electron acoustic waves: The Landau damping and ion contribution in the spectrum

    NASA Astrophysics Data System (ADS)

    Andreev, Pavel A.

    2016-06-01

    Separated spin-up and spin-down quantum kinetics is derived for more detailed research of the spin-electron acoustic waves (SEAWs). This kinetic theory allows us to obtain the spectrum of the SEAWs including the effects of occupation of quantum states more accurately than the quantum hydrodynamic theory. We derive and apply the quantum kinetic theory to calculate the Landau damping of the SEAWs. We consider the contribution of ions dynamics into the SEAW spectrum. We obtain the contribution of ions in the Landau damping in the temperature regime of classic ions. Kinetic analysis for the ion-acoustic, zero sound, and Langmuir waves at the separated spin-up and spin-down electron dynamics is presented as well.

  18. Time periodic spatial disorder in a complex Ginzburg{endash}Landau equation

    SciTech Connect

    Bazhenov, M.; Rabinovich, M.; Rubchinsky, L.

    1996-06-01

    The phenomenon of time-periodic evolution of spatial chaos (1) is investigated in the frame of a one and two-dimensional complex Ginzburg{endash}Landau equation. It is found that there exists a region of the parameters at which a disordered spatial distribution of the field behaves periodically in time; the boundaries of this region are determined. A system of ordinary differential equations describing spatial disorder is derived. The effect of the size of the system on the shape and period of oscillations is investigated. It is established that in a two-dimensional case the regime of time periodic spatial disorder arises only in the narrow band and the critical width of the band is estimated. The phenomenon investigated in this paper indicates that a family of limit cycles with finite basins may exist in the functional phase space of complex Ginzburg{endash}Landau equation in finite regions of the parameters. {copyright} {ital 1996 American Institute of Physics.}

  19. Landau pole in the Standard Model with weakly interacting scalar fields

    NASA Astrophysics Data System (ADS)

    Hamada, Yuta; Kawana, Kiyoharu; Tsumura, Koji

    2015-07-01

    We consider the Standard Model with a new scalar field X which is an nX representation of the SU (2)L with a hypercharge YX. The renormalization group running effects on the new scalar quartic coupling constants are evaluated. Even if we set the scalar quartic coupling constants to be zero at the scale of the new scalar field, the coupling constants are induced by the one-loop effect of the weak gauge bosons. Once non-vanishing couplings are generated, the couplings rapidly increase by renormalization group effect of the quartic coupling constant itself. As a result, the Landau pole appears below Planck scale if nX ≥ 4. We find that the scale of the obtained Landau pole is much lower than that evaluated by solving the one-loop beta function of the gauge coupling constants.

  20. Experimental observation of surface states and Landau levels bending in bilayer graphene

    NASA Astrophysics Data System (ADS)

    Yin, Long-Jing; Zhang, Yu; Qiao, Jia-Bin; Li, Si-Yu; He, Lin

    2016-03-01

    We report on microscopic measurements of the low-energy electronic structures both at the zigzag and armchair edges of bilayer graphene using scanning tunneling microscopy and spectroscopy (STM and STS). We have found that, both in the absence and in the presence of a magnetic field, an almost zero-energy peak in the density of states was localized at the zigzag edges, as expected for the surface states at the zigzag edges of bilayer graphene. In the quantum Hall regime, we have clearly observed Landau levels bending away from the charge neutrality point near both the zigzag and armchair edges. Such a result is direct evidence for the evolution of Landau levels into quantum Hall edge states in graphene bilayers. Our experiment indicates that it is possible to explore rich quantum Hall physics in graphene systems using STM and STS.

  1. Fragile Fractional Quantum Hall States in the Lowest and the Second Landau Level

    NASA Astrophysics Data System (ADS)

    Csathy, Gabor; Kleinbaum, Ethan; Kumar, Ashwani; Samkharadze, Nodar; Pfeiffer, Loren; West, Ken

    Ultra-low temperature measurements of the two-dimensional electron gas have revealed some of the most fragile fractional quantum Hall states. In these experiments electron thermalization was achieved using a He-3 immersion cell and the temperature of the bath is monitored using a quartz tuning fork viscometer. We will review the recently discovered fractional quantum Hall state at filling factor ν = 3 + 1 / 3 observed in the second Landau level and those at the filling factor ν = 4 / 11 and 5 / 13 in the lowest Landau level. The work at Purdue was supported by NSF DMR 1207375 and 1505866 grants. The work at Princeton University was funded by the Gordon and Betty Moore Foundation through the EPiQS initiative Grant GBMF4420, and by the National Science Foundation MRSEC Grant DMR-1420541.

  2. Surface Landau levels and spin states in bismuth (111) ultrathin films

    PubMed Central

    Du, Hongjian; Sun, Xia; Liu, Xiaogang; Wu, Xiaojun; Wang, Jufeng; Tian, Mingyang; Zhao, Aidi; Luo, Yi; Yang, Jinlong; Wang, Bing; Hou, J. G.

    2016-01-01

    The development of next-generation electronics is much dependent on the discovery of materials with exceptional surface-state spin and valley properties. Because of that, bismuth has attracted a renewed interest in recent years. However, despite extensive studies, the intrinsic electronic transport properties of Bi surfaces are largely undetermined due to the strong interference from the bulk. Here we report the unambiguous determination of the surface-state Landau levels in Bi (111) ultrathin films using scanning tunnelling microscopy under magnetic fields perpendicular to the surface. The Landau levels of the electron-like and the hole-like carriers are accurately characterized and well described by the band structure of the Bi (111) surface from density functional theory calculations. Some specific surface spin states with a large g-factor are identified. Our findings shed light on the exploiting surface-state properties of Bi for their applications in spintronics and valleytronics. PMID:26964494

  3. Time-resolved measurement of Landau-Zener tunneling in different bases

    SciTech Connect

    Tayebirad, G.; Loerch, N.; Wimberger, S.; Zenesini, A.; Ciampini, D.; Arimondo, E.; Mannella, R.; Morsch, O.

    2010-07-15

    A comprehensive study of the tunneling dynamics of a Bose-Einstein condensate in a tilted periodic potential is presented. We report numerical and experimental results on time-resolved measurements of the Landau-Zener tunneling of ultracold atoms introduced by the tilt, which experimentally is realized by accelerating the lattice. The use of different protocols enables us to access the tunneling probability, numerically as well as experimentally, in two different bases, namely, the adiabatic basis and the diabatic basis. The adiabatic basis corresponds to the eigenstates of the lattice, and the diabatic one to the free-particle momentum eigenstates. Our numerical and experimental results are compared with existing two-state Landau-Zener models.

  4. Observation of Landau-Zener tunneling through atomic current in the optical lattices

    SciTech Connect

    Yan Jieyun; Duan Suqing; Zhang Wei; Zhao Xiangeng

    2009-05-15

    The atomic current in the Fourier-synthesized optical lattices under a constant external force is investigated theoretically. Based on a two-band model, the atomic current is derived by solving the Boltzmann equations. We find that the stationary atomic current changes with the probability of Landau-Zener tunneling, depending on the adjustable energy structure of the optical lattices. In contrast to the classical results of an electron in superlattices given by the Esaki-Tsu equations, the relation between the stationary atomic current and the strength of the external force in optical lattices is modified significantly. Both these characteristics can be taken as an effective way to observe the Landau-Zener tunneling in the optical lattices.

  5. Landau-Zener transitions mediated by an environment in the open-multistate model

    NASA Astrophysics Data System (ADS)

    Garmon, Savannah; Dodin, Amro; Simine, Lena; Segal, Dvira

    2015-03-01

    We study Landau-Zener transitions between two linearly driven states with the addition of a shared discretized continuum. The continuum allows for population decay from the initial state as well as indirect transitions. The probability of nonadiabatic transition in this model preserves the standard Landau-Zener functional form apart from a shift in the usual exponential factor, reflecting population transfer into the continuum. We provide an intuitive explanation for this behavior assuming individual, independent transitions between pairs of states. In contrast, the ground state survival probability at long time shows a novel, non-monotonic, functional form with an oscillatory behavior in the sweep rate at low sweep rate values. We envision our system as a simplified model regarding memory preservation in a quantum dot as the dot interacts with the surrounding environment.

  6. Effect of Charge Noise on Landau-Zener Interferometry in double quantum dots

    NASA Astrophysics Data System (ADS)

    Qi, Zhenyi; Friesen, Mark; Coppersmith, Susan; Vavilov, Maxim

    We study the effect of charge noise on the dynamics of semiconductor quantum dot qubits. Recent experiments have demonstrated relatively long coherence times in these systems; however at the same time, the visibility of the Landau-Zener interference pattern is relatively low. We argue that the electromagnetic noise of the environment affects the coherence of the qubit near the charge degeneracy point, including the singlet-triplet avoided level crossing, and results in the reduced visibility of the Landau-Zener interferometry when the singlet-triplet avoided level crossing happens in the vicinity of the charge degeneracy point. Using a master equation, we describe the evolution of the density matrix for the qubit assuming weak coupling of the quantum dot to its electromagnetic environment and compare our results to experimental data.

  7. Dissipative Landau-Zener transitions of a qubit: Bath-specific and universal behavior

    SciTech Connect

    Saito, Keiji; Wubs, Martijn; Kohler, Sigmund; Haenggi, Peter; Kayanuma, Yosuke

    2007-06-01

    We study Landau-Zener transitions in a qubit coupled to a bath at zero temperature. A general formula that is applicable to models with a nondegenerate ground state is derived. We calculate exact transition probabilities for a qubit coupled to either a bosonic or a spin bath. The nature of the baths and the qubit-bath coupling is reflected in the transition probabilities. For diagonal coupling, when the bath causes energy fluctuations of the diabatic qubit states but no transitions between them, the transition probability coincides with the standard Landau-Zener probability of an isolated qubit. This result is universal as it does not depend on the specific type of bath. For pure off-diagonal coupling, by contrast, the tunneling probability is sensitive to the coupling strength. We discuss the relevance of our results for experiments on molecular nanomagnets, in circuit QED, and for the fast-pulse readout of superconducting phase qubits.

  8. Dissipative Landau-Zener quantum dynamics with transversal and longitudinal noise

    NASA Astrophysics Data System (ADS)

    Javanbakht, S.; Nalbach, P.; Thorwart, M.

    2015-05-01

    We determine the Landau-Zener transition probability in a dissipative environment including both longitudinal as well as transversal quantum-mechanical noise originating from a single noise source. For this, we use the numerically exact quasiadiabatic path integral, as well as the approximative nonequilibrium Bloch equations. We find that transversal quantum noise in general influences the Landau-Zener probability much more strongly than longitudinal quantum noise does at a given temperature and system-bath coupling strength. In other words, transversal noise contributions become important even when the coupling strength of transversal noise is smaller than that of longitudinal noise. We furthermore reveal that transversal noise renormalizes the tunnel coupling independent of temperature. Finally, we show that the effect of mixed longitudinal and transversal noise originating from a single bath cannot be obtained from an incoherent sum of purely longitudinal and purely transversal noise.

  9. More on the properties of the first Gribov region in Landau gauge

    NASA Astrophysics Data System (ADS)

    Maas, Axel

    2016-03-01

    Complete gauge fixing beyond perturbation theory in non-Abelian gauge theories is a nontrivial problem. This is particularly evident in covariant gauges, where the Gribov-Singer ambiguity gives an explicit formulation of the problem. In practice, this is a problem if gauge-dependent quantities between different methods, especially lattice and continuum methods, should be compared: Only when treating the Gribov-Singer ambiguity in the same way is the comparison meaningful. To provide a better basis for such a comparison the structure of the first Gribov region in Landau gauge, a subset of all possible gauge copies satisfying the perturbative Landau gauge condition, will be investigated. To this end, lattice gauge theory will be used to investigate a two-dimensional projection of the region for SU(2) Yang-Mills theory in two, three, and four dimensions for a wide range of volumes and discretizations.

  10. Observation of new fractional quantum Hall states in the first Landau level in graphene

    NASA Astrophysics Data System (ADS)

    Amet, Francois; Bestwick, Andrew; Williams, James; Watanabe, Kenji; Taniguchi, Takahashi; Goldhaber-Gordon, David

    2014-03-01

    We report on transport studies of the fractional quantum Hall effect in the n=0 and n=1 Landau level of monolayer graphene. The quality of the devices studied here -with mobilities up to 400 000cm2/Vs, and magnetic fields up to 45T- allows us to observe a variety of fractional quantum hall states following the composite fermion sequence, with denominators up to 9. The presence of odd numerator fractions between nu=1 and nu=2 is attributed to the breaking of the valley symmetry and correlates with a zero field insulating state observed at charge neutrality. We discuss the in-plane field dependence of the gaps, which is not trivial and shows dramatic differences between the n=0 and the n=1 Landau levels.

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

    NASA Astrophysics Data System (ADS)

    Chhaiba, Hassan; Demni, Nizar; Mouayn, Zouhair

    2016-07-01

    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.

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

    SciTech Connect

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

    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.

  13. The dynamics of vortex filaments in the complex Ginzburg- Landau equation

    NASA Astrophysics Data System (ADS)

    Gabbay, Michael

    1997-09-01

    An asymptotic theory is developed for scroll waves in the complex Ginzburg-Landau equation. The theory is valid in the limit of small vortex filament curvature, torsion and phase twist and in the absence of filament-filament interaction. Explicit expressions for the filament velocity and phase evolution are found. The theoretical results are verified numerically in the case of circular untwisted vortex rings and for straight and sinusoidal filaments with phase twist. Numerical evidence for the reconnection of vortex filaments in the complex Ginzburg- Landau equation is shown. An estimate is given for the maximum intervortex separation beyond which coplanar filaments of locally opposite charge will not reconnect. This is done by balancing the motion of the filaments toward each other that would result if they were straight (a two-dimensional effect) with the opposing motion due to the filament curvature. The estimated vortex separation is in good agreement with numerical experiment.

  14. Domain Wall Dynamics in Ginzburg-Landau-Type Equations with Conservative Quantities

    NASA Astrophysics Data System (ADS)

    Sakaguchi, Hidetsugu; Akamine, Hiroshi

    2014-06-01

    In the Ginzburg-Landau equation, there are domain walls connecting two metastable states. The dynamics of domain walls has been intensively studied, but there remain still unsolved but crucial problems even for a single domain. We study the domain wall dynamics in three different Ginzburg-Landau-type equations satisfying conservation laws. In a modified ϕ4 model satisfying the law of energy conservation and the Lorentz invariance, the motion of a domain wall is accelerated and the velocity approaches its maximum. In a one-dimensional model of eutectic growth, the order parameter is conserved and a domain wall connecting a metastable uniform state and a spatially periodic pattern appears. We try to find a selection rule for the wavelength of a spatially periodic pattern. In a model equation for martensitic transformation, a domain wall connecting a uniform metastable state and a zigzag structure appears which propagates at a high velocity.

  15. Ginzburg-Landau model for a free-electron laser: from single mode to spikes

    NASA Astrophysics Data System (ADS)

    Ng, C. S.; Bhattacharjee, A.

    1998-02-01

    Single-mode operation of a free-electron laser is modeled by the Ginzburg-Landau equation. The linear stability of a single-mode solution is analyzed, and connections are established with known instabilities of the Ginzburg-Landau equation. It is found that there is no Benjamin-Feir instability and hence, the principal mode with the largest gain is always stable. However, the Eckhaus (or the phase) instability generally exists for a mode with frequency outside a range centered on the principal mode. This gives rise to two distinct possibilities: either there is spontaneous frequency shifting to the stable mode with the largest growth rate and a consequent tendency to approach single-mode operation, or there is a sudden chaotization and spikiness in the radiation field. Analytical criteria and scaling are given and tested by numerical simulations.

  16. Strong Zeeman effects in the Landau level spectrum of (InxBi1-x)2 Se3

    NASA Astrophysics Data System (ADS)

    Walkup, Daniel; Zhou, Wenwen; Zeljkovic, Ilija; Okada, Yoshinori; Ren, Zhensong; Scipioni, Kane; Wilson, Stephen; Madhavan, Vidya

    We investigate the surface states of (InxBi1-x)2 Se3 by scanning tunneling spectroscopy (STS) in the range 0 <= x 3%. We carefully examine the low-lying Landau levels of the topological surface states in attempt to extract the parameters of the surface-state Hamiltonian as a function of doping. Close examination of the data oblige us to index the Landau levels in a manner different to precedent on pristine Bi2Se3, and fits to the Landau level spectra yield large g-factors on the order of 40, which decrease with increasing x. The Landau levels of pristine Bi2Se3 are also reexamined, yielding high g-factors roughly consistent with results obtained from magnetic oscillations, and suggesting a decrease in the surface-state Zeeman coupling with increasing In as the topological phase transition is approached.

  17. Observation of the correspondence between Landau-Zener transition and Kibble-Zurek mechanism with a superconducting qubit system

    NASA Astrophysics Data System (ADS)

    Gong, Ming; Lan, Dong; Liu, Yuhao; Tan, Xinsheng; Yu, Haifeng; Yu, Yang; Zhu, Shiliang; Sun, Guozhu; Zhou, Yu; Fan, Yunyi; Wu, Peiheng; Wen, Xueda; Zhang, Danwei; Han, Siyuan

    We present a direct experimental observation of the correspondence between Landau-Zener transition and Kibble-Zurek mechanism with a superconducting qubit system. We develop a time resolved approach to study quantum dynamics of the Landau-Zener transition. By using this method, we observe the key features of the correspondence between Landau-Zener transition and Kibble-Zurek mechanism, e.g., the boundary between the adiabatic and impulse regions, the freeze out phenomenon in the impulse region. Remarkably, the scaling behavior of the population in the excited state, an analogical phenomenon originally predicted in Kibble-Zurek mechanism, is also observed in the Landau-Zener transition. This work was partly supported by the SKPBR of China (2011CB922104), NSFC (91321310, 11125417, 11474153, 11474154, 61521001), and the PCSIRT (Grant No. IRT1243).

  18. Ressourceneinsatzplanung In der Energie- und Verfahrenstechnik

    NASA Astrophysics Data System (ADS)

    Engell, Sebastian; Handschin, Edmund; Rehtanz, Christian; Schultz, Rüdiger

    Der ökologisch nachhaltige, wirtschaftlich effiziente und politisch faire Umgang mit den Ressourcen der Erde ist eine der größten Herausforderungen an die Menschheit im 21. Jahrhundert und impliziert Paradigmenwechsel in allen Bereichen des gesellschaftlichen Lebens. Energie- und Verfahrenstechnik sind traditionell Bereiche, in denen der optimale Umgang mit kostbaren und beschränkt verfügbaren Ressourcen von erstrangiger Bedeutung ist. Zur Lösung der damit verbundenen komplexen Entscheidungsprobleme sind mathematische Methoden schon seit längerem im Einsatz. Hierbei können aber noch längst nicht alle bislang aufgetretenen Probleme fundiert angegangen werden. Der wachsende wirtschaftliche und ökologische Druck auf die Effizienz der Produktions-und Versorgungssysteme sowie stärkere Schwankungen von Angebot und Nachfrage führen zu neuen Herausforderungen, für die neue mathematische Methoden und Algorithmen entwickelt werden müssen.

  19. Landau damping of Gardner solitons in a dusty bi-ion plasma

    NASA Astrophysics Data System (ADS)

    Misra, A. P.; Barman, Arnab

    2015-07-01

    The effects of linear Landau damping on the nonlinear propagation of dust-acoustic solitary waves (DASWs) are studied in a collisionless unmagnetized dusty plasma with two species of positive ions. The extremely massive, micron-seized, cold, and negatively charged dust particles are described by fluid equations, whereas the two species of positive ions, namely, the cold (heavy) and hot (light) ions are described by the kinetic Vlasov equations. Following Ott and Sudan [Phys. Fluids 12, 2388 (1969)], and by considering lower and higher-order perturbations, the evolution of DASWs with Landau damping is shown to be governed by Korteweg-de Vries (KdV), modified KdV (mKdV), or Gardner (KdV-mKdV)-like equations. The properties of the phase velocity and the Landau damping rate of DASWs are studied for different values of the ratios of the temperatures (σ) and the number densities (μ) of hot and cold ions as well as the cold to hot ion mass ratio m. The distinctive features of the decay rates of the amplitudes of the KdV, mKdV, and Gardner solitons with a small effect of Landau damping are also studied in different parameter regimes. It is found that the Gardner soliton points to lower wave amplitudes than the KdV and mKdV solitons. The results may be useful for understanding the localization of solitary pulses and associated wave damping (collisionless) in laboratory and space plasmas (e.g., the F-ring of Saturn), in which the number density of free electrons is much smaller than that of ions and the heavy, micron seized dust grains are highly charged.

  20. Generalized stochastic Landau-Lifshitz-Gilbert equation for yttrium-iron garnet films

    NASA Astrophysics Data System (ADS)

    Rückriegel, Andreas; Kopietz, Peter

    2015-03-01

    We derive a generalization of the well-known stochastic Landau-Lifshitz-Gilbert equation starting from a microscopic Heisenberg model coupled to the lattice degrees of freedom. By integrating out the phonons we obtain a non-Markovian, stochastic equation of motion for the spin degrees of freedom satisfying a Fluctuation-Dissipation theorem. We apply our theory to study the parametric pumping and thermalization of spin excitations in thin yttrium-iron garnet films.

  1. Wang-Landau sampling in face-centered-cubic hydrophobic-hydrophilic lattice model proteins

    NASA Astrophysics Data System (ADS)

    Liu, Jingfa; Song, Beibei; Yao, Yonglei; Xue, Yu; Liu, Wenjie; Liu, Zhaoxia

    2014-10-01

    Finding the global minimum-energy structure is one of the main problems of protein structure prediction. The face-centered-cubic (fcc) hydrophobic-hydrophilic (HP) lattice model can reach high approximation ratios of real protein structures, so the fcc lattice model is a good choice to predict the protein structures. The lacking of an effective global optimization method is the key obstacle in solving this problem. The Wang-Landau sampling method is especially useful for complex systems with a rough energy landscape and has been successfully applied to solving many optimization problems. We apply the improved Wang-Landau (IWL) sampling method, which incorporates the generation of an initial conformation based on the greedy strategy and the neighborhood strategy based on pull moves into the Wang-Landau sampling method to predict the protein structures on the fcc HP lattice model. Unlike conventional Monte Carlo simulations that generate a probability distribution at a given temperature, the Wang-Landau sampling method can estimate the density of states accurately via a random walk, which produces a flat histogram in energy space. We test 12 general benchmark instances on both two-dimensional and three-dimensional (3D) fcc HP lattice models. The lowest energies by the IWL sampling method are as good as or better than those of other methods in the literature for all instances. We then test five sets of larger-scale instances, denoted by the S, R, F90, F180, and CASP target instances on the 3D fcc HP lattice model. The numerical results show that our algorithm performs better than the other five methods in the literature on both the lowest energies and the average lowest energies in all runs. The IWL sampling method turns out to be a powerful tool to study the structure prediction of the fcc HP lattice model proteins.

  2. Collective nature of the reentrant integer quantum Hall states in the second Landau level.

    PubMed

    Deng, N; Kumar, A; Manfra, M J; Pfeiffer, L N; West, K W; Csáthy, G A

    2012-02-24

    We report an unexpected sharp peak in the temperature dependence of the magnetoresistance of the reentrant integer quantum Hall states in the second Landau level. This peak defines the onset temperature of these states. We find that in different spin branches the onset temperatures of the reentrant states scale with the Coulomb energy. This scaling provides direct evidence that Coulomb interactions play an important role in the formation of these reentrant states evincing their collective nature. PMID:22463555

  3. Collective Nature of the Reentrant Integer Quantum Hall States in the Second Landau Level

    NASA Astrophysics Data System (ADS)

    Deng, N.; Kumar, A.; Manfra, M. J.; Pfeiffer, L. N.; West, K. W.; Csáthy, G. A.

    2012-02-01

    We report an unexpected sharp peak in the temperature dependence of the magnetoresistance of the reentrant integer quantum Hall states in the second Landau level. This peak defines the onset temperature of these states. We find that in different spin branches the onset temperatures of the reentrant states scale with the Coulomb energy. This scaling provides direct evidence that Coulomb interactions play an important role in the formation of these reentrant states evincing their collective nature.

  4. Exploring new frontiers in statistical physics with a new, parallel Wang-Landau framework

    SciTech Connect

    Vogel, Thomas; Li, Ying Wai; Wuest, Thomas; Landau, David P

    2014-01-01

    Combining traditional Wang Landau sampling for multiple replica systems with an exchange of densities of states between replicas we describe a general framework for simulations on massively parallel Petaflop supercomputers. The advantages and general applicability of the method for simulations of complex systems are demonstrated for the classical 2D Potts spin model featuring a strong first-order transition and the self-assembly of lipid bilayers in amphiphilic solutions in a continuous model.

  5. Landau level spin diode in a GaAs two dimensional hole system

    NASA Astrophysics Data System (ADS)

    Klochan, O.; Hamilton, A. R.; das Gupta, K.; Sfigakis, F.; Beere, H. E.; Ritchie, D. A.

    2015-03-01

    We have fabricated and characterized a Landau level spin diode in a GaAs two-dimensional hole system. We used the spin diode to probe the hyperfine coupling between hole and nuclear spins and found no detectable net nuclear spin polarization, indicating that hole-nuclear spin flip-flop processes are suppressed by at least factor of 50 compared to GaAs electron systems.

  6. Simulation of linear and nonlinear Landau damping of lower hybrid waves

    NASA Astrophysics Data System (ADS)

    Qi, Lei; Wang, X. Y.; Lin, Y.

    2013-06-01

    The linear physics of lower hybrid waves (LHWs) and their nonlinear interaction with particles through Landau damping are studied with the gyrokinetic electron and fully kinetic ion (GeFi) particle simulation model in the electrostatic limit. Unlike most other wave modes, the LHWs can resonantly interact with both electrons and ions, with the former being highly magnetized and latter nearly unmagnetized around the lower hybrid frequency. Direct interactions of LHWs with electrons and/or ions are investigated for cases with various k∥/k ,Ti/Te, and wave amplitudes. In the linear electron Landau damping (ELD), the dispersion relation and the linear damping rate obtained from our simulation agree well with the analytical linear theory. As the wave amplitude increases, the nonlinear Landau effects are present, and a transition from strong decay at smaller amplitudes to weak decay at larger amplitudes is observed. In the nonlinear stage, the LHWs in the long time evolution finally exhibit a steady Bernstein-Greene-Kruskal mode, in which the wave amplitude is saturated above the noise level. While the resonant electrons are trapped in the wave field in the nonlinear ELD, the resonant ions are untrapped in the LHW time scales. The ion Landau damping is thus predominantly in a linear fashion, leading to a wave saturation level significantly lower than that in the ELD. On the long time scales, however, the ions are still weakly trapped. The results show a coupling between the LHW frequency and the ion cyclotron frequency during the long-time LHW evolution.

  7. Generalized Klauder-Perelomov and Gazeau-Klauder coherent states for Landau levels

    NASA Astrophysics Data System (ADS)

    Fakhri, H.

    2003-07-01

    Based on a pair of representations obtained for Lie algebra h4, the Hilbert space corresponding to all quantum states of Landau levels is split into an infinite direct sum of infinite-dimensional Hilbert subspaces. For any one of the Hilbert subspaces, we get linear combinations of their bases as generalized coherent states-the so-called Klauder-Perelomov and Gazeau-Klauder.

  8. Sobolev gradient approach for the time evolution related to energy minimization of Ginzburg-Landau functionals

    NASA Astrophysics Data System (ADS)

    Raza, Nauman; Sial, Sultan; Siddiqi, Shahid S.

    2009-04-01

    The Sobolev gradient technique has been discussed previously in this journal as an efficient method for finding energy minima of certain Ginzburg-Landau type functionals [S. Sial, J. Neuberger, T. Lookman, A. Saxena, Energy minimization using Sobolev gradients: application to phase separation and ordering, J. Comput. Phys. 189 (2003) 88-97]. In this article a Sobolev gradient method for the related time evolution is discussed.

  9. Exact Lyapunov dimension of the universal attractor for the complex Ginzburg-Landau equation

    SciTech Connect

    Doering, C.R.; Gibbon, J.D.; Holm, D.D.; Nicolaenko, B.

    1987-12-28

    We present an exact analytic computation of the Lyapunov dimension of the universal attractor of the complex Ginzburg-Landau partial differential equation for a finite range of its parameter values. We obtain upper bounds on the attractor's dimension when the parameters do not permit an exact evaluation by our methods. The exact Lyapunov dimension agrees with an estimate of the number of degrees of freedom based on a simple linear stability analysis and mode-counting argument.

  10. Solvable multistate model of Landau-Zener transitions in cavity QED

    NASA Astrophysics Data System (ADS)

    Sinitsyn, Nikolai A.; Li, Fuxiang

    2016-06-01

    We consider the model of a single optical cavity mode interacting with two-level systems (spins) driven by a linearly time-dependent field. When this field passes through values at which spin energy-level splittings become comparable to spin coupling to the optical mode, a cascade of Landau-Zener transitions leads to coflips of spins in exchange for photons of the cavity. We derive exact transition probabilities between different diabatic states induced by such a sweep of the field.

  11. The Lorentz-Dirac and Landau-Lifshitz equations from the perspective of modern renormalization theory

    NASA Astrophysics Data System (ADS)

    Nakhleh, Charles W.

    2013-03-01

    This paper uses elementary techniques drawn from renormalization theory to derive the Lorentz-Dirac equation for the relativistic classical electron from the Maxwell-Lorentz equations for a classical charged particle coupled to the electromagnetic field. I show that the resulting effective theory, valid for electron motions that change over distances large compared to the classical electron radius, reduces naturally to the Landau-Lifshitz equation. No familiarity with renormalization or quantum field theory is assumed.

  12. Landau damping effects and evolutions of energy spread in small isochronous ring

    SciTech Connect

    Li, Yingjie; Wang, Langfa; Lin, Fanglei

    2014-11-01

    This paper presents the Landau damping effects on the microwave instability of a coasting long bunch in an isochronous ring due to finite energy spread and emittance. Our two-dimensional (2D) dispersion relation gives more accurate predictions of the microwave instability growth rates of short-wavelength perturbations than the conventional 1D formula. The long-term evolution of energy spread is also studied by measurements and simulations.

  13. The stability of the radial solution to the Ginzburg-Landau equation

    SciTech Connect

    Tai-Chia Lin

    1997-11-01

    In this paper, we consider the the Ginzburg-Landau equation -{del}u = 1/2 u (1 - {vert_bar}u{vert_bar}{sup 2}) in B u = g on {partial_derivative}B where B is the unit ball in R{sup 2} with center at the origin, g(e{sup i0} = e{sup id)}, d = 1,2,3,..., u:B {yields} C is smooth, and {epsilon} > 0 is a small parameter.

  14. Implicit integration of the time-dependent Ginzburg-Landau equations of superconductivity.

    SciTech Connect

    Gunter, D. O.; Kaper, H. G.; Leaf, G. K.; Mathematics and Computer Science

    2002-05-17

    This article is concerned with the integration of the time-dependent Ginzburg-Landau (TDGL) equations of superconductivity. Four algorithms, ranging from fully explicit to nonlinearly implicit, are presented and evaluated for stability, accuracy, and compute time. The benchmark problem for the evaluation is the equilibration of a vortex configuration in a superconductor that is embedded in a thin insulator and subject to an applied magnetic field.

  15. The frozen-field approximation and the Ginzburg-Landau equations of superconductivity.

    SciTech Connect

    Kaper, H. G.; Nordborg, H.; Univ. of Chicago

    2001-03-01

    The Ginzburg-Landau (GL) equations of superconductivity provide a computational model for the study of magnetic flux vortices in type-II superconductors. In this article it is shown through numerical examples and rigorous mathematical analysis that the GL model reduces to the frozen-field model when the charge of the Cooper pairs (the superconducting charge carriers) goes to zero while the applied field stays near the upper critical field.

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

    SciTech Connect

    Dimits, A. M. Joseph, I.; Umansky, M. V.

    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. Quantum statistical foundation to the Fermi liquid model and Ginzburg-Landau wave function

    SciTech Connect

    Fujita, Shigeji; Godoy, S. )

    1993-12-01

    An energy eigenvalue equation for a quasi-particle is derived, starting with the Heisenberg equation of motion for an annihilation operator. An elementary derivation of the Fermi liquid model having a sharply defined Fermi surface in the k-space is given, starting with a realistic model of a metal including the Coulomb interaction among and between electrons and lattice-ions. The Ginzburg-Landau wave function [Psi][sub [sigma

  18. Direct observation of Landau-Zener tunneling in a curved optical waveguide coupler

    SciTech Connect

    Dreisow, F.; Szameit, A.; Heinrich, M.; Nolte, S.; Tuennermann, A.; Ornigotti, M.; Longhi, S.

    2009-05-15

    An electromagnetic realization of Landau-Zener (LZ) tunneling is experimentally demonstrated in femtosecond-laser written waveguide couplers with a cubically bent axis. Quantitative measurements of light evolution inside the coupler, based on fluorescence imaging, enable to trace the detailed dynamics of the LZ process. The experimental results are in good agreement with the theoretical LZ model for linear crossing of energy levels with constant coupling of finite duration.

  19. The finite time multi-level SU(2) Landau-Zener problems: exact analytical results

    NASA Astrophysics Data System (ADS)

    Mkam Tchouobiap, S. E.; Kenmoe, M. B.; Fai, L. C.

    2015-10-01

    The multi-level SU(2) Landau-Zener problem is analytically solved at finite time within the framework of the Bloch tensor formalism and with the help of the disentanglement Wei-Norman ordering technique. A generalized and exact analytical solution is achieved that accounts not only for all projections of an arbitrary spin S along the Zeeman field direction but also for non-adiabatic and adiabatic evolutions.

  20. Atomic Landau-Zener tunneling and Wannier-Stark ladders in optical potentials

    SciTech Connect

    Niu, Q.; Zhao, X.; Georgakis, G.; Raizen, M.

    1996-06-01

    We calculate the quantum motion of ultracold atoms in an accelerating optical potential, and show how they may be used to observe Landau-Zener tunneling and Wannier-Stark ladders, two fundamental quantum effects in solid state physics. The optical potential is spatially periodic, yielding an energy spectrum of Bloch bands for the atoms. The acceleration provides an inertial force in the moving frame, emulating an electric force on Bloch electrons. {copyright} {ital 1996 The American Physical Society.}

  1. Visibility study of S -T+ Landau-Zener-Stückelberg oscillations without applied initialization

    NASA Astrophysics Data System (ADS)

    Granger, G.; Aers, G. C.; Studenikin, S. A.; Kam, A.; Zawadzki, P.; Wasilewski, Z. R.; Sachrajda, A. S.

    2015-03-01

    Probabilities deduced from quantum information studies are usually based on averaging many identical experiments separated by an initialization step. Such initialization steps become experimentally more challenging to implement as the complexity of quantum circuits increases. To better understand the consequences of imperfect initialization on the deduced probabilities, we study the effect of not initializing the system between measurements. For this we utilize Landau-Zener-Stückelberg oscillations in a double quantum dot circuit. Experimental results are successfully compared to theoretical simulations.

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

    SciTech Connect

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

    1987-01-01

    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 /sup 13/C(/sup 12/C, /sup 12/C)/sup 13/C/sup */ (3.086 MeV, (1/2)/sup +/). The evidence stems from characteristic changes of the angular distributions observed as a function of the incident energy.

  3. Stability of the Melting Hedgehog in the Landau-de Gennes Theory of Nematic Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Ignat, Radu; Nguyen, Luc; Slastikov, Valeriy; Zarnescu, Arghir

    2014-09-01

    We investigate stability properties of the radially symmetric solution corresponding to the vortex defect (the so called "melting hedgehog") in the framework of the Landau-de Gennes model of nematic liquid crystals. We prove local stability of the melting hedgehog under arbitrary Q-tensor valued perturbations in the temperature regime near the critical supercooling temperature. As a consequence of our method, we also rediscover the loss of stability of the vortex defect in the deep nematic regime.

  4. Stability of the Melting Hedgehog in the Landau-de Gennes Theory of Nematic Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Ignat, Radu; Nguyen, Luc; Slastikov, Valeriy; Zarnescu, Arghir

    2015-02-01

    We investigate stability properties of the radially symmetric solution corresponding to the vortex defect (the so called "melting hedgehog") in the framework of the Landau-de Gennes model of nematic liquid crystals. We prove local stability of the melting hedgehog under arbitrary Q-tensor valued perturbations in the temperature regime near the critical supercooling temperature. As a consequence of our method, we also rediscover the loss of stability of the vortex defect in the deep nematic regime.

  5. Landau Level Splittings, Phase Transitions, and Nonuniform Charge Distribution in Trilayer Graphene

    NASA Astrophysics Data System (ADS)

    Campos, Leonardo C.; Taychatanapat, Thiti; Serbyn, Maksym; Surakitbovorn, Kawin; Watanabe, Kenji; Taniguchi, Takashi; Abanin, Dmitry A.; Jarillo-Herrero, Pablo

    2016-08-01

    We report on magnetotransport studies of dual-gated, Bernal-stacked trilayer graphene (TLG) encapsulated in boron nitride crystals. We observe a quantum Hall effect staircase which indicates a complete lifting of the 12-fold degeneracy of the zeroth Landau level. As a function of perpendicular electric field, our data exhibit a sequence of phase transitions between all integer quantum Hall states in the filling factor interval -8 <ν <0 . We develop a theoretical model and argue that, in contrast to monolayer and bilayer graphene, the observed Landau level splittings and quantum Hall phase transitions can be understood within a single-particle picture, but imply the presence of a charge density imbalance between the inner and outer layers of TLG, even at charge neutrality and zero transverse electric field. Our results indicate the importance of a previously unaccounted band structure parameter which, together with a more accurate estimate of the other tight-binding parameters, results in a significantly improved determination of the electronic and Landau level structure of TLG.

  6. Longitudinal oscillations and linear Landau damping in quark-gluon plasma.

    PubMed

    Murtaza, G; Khattak, N A D; Shah, H A

    2003-12-01

    On the basis of the semiclassical kinetic Vlasov equation for quark-gluon plasma and the Yang-Mills equation in covariant gauge, linear Landau damping for electrostatic perturbations such as Langmuir waves is investigated for the extreme-relativistic and strongly relativistic cases. It has been observed that for the extreme-relativistic case, wherein the thermal speed of the particles exceeds the phase velocity of the perturbations, the linear Landau damping is absent as has been reported in the literature. However, a departure from extreme-relativistic case generates an imaginary component of the frequency giving rise to linear Landau damping effect. The relevant integral for the conductivity tensor has been evaluated and the dispersion relation for the longitudinal part of the oscillation was obtained. Further, it is also noted that both the real part of the oscillation frequency and the damping rate are sensitive to the choice of the wave number k and the Debye length lambda(D) associated with quark-gluon plasma. PMID:14754324

  7. Spontaneous polarization of composite fermions in the n = 1 Landau level of graphene

    NASA Astrophysics Data System (ADS)

    Coimbatore Balram, Ajit; Tőke, Csaba; Wójs, Arkadiusz; Jain, Jainendra

    Motivated by experiments that reveal expansive fractional quantum Hall states in the n = 1 graphene Landau level and suggest a nontrivial role of the spin degree of freedom [Amet et al., Nat. Commun. 6, 5838 (2014)], we perform accurate quantitative study of the the competition between fractional quantum Hall states with different spin polarizations in the n = 1 graphene Landau level. We find that the fractional quantum Hall effect is well described in terms of composite fermions, but the spin physics is qualitatively different from that in the n = 0 Landau level. In particular, for the states at filling factors ν = s / (2 s +/- 1) , s integer, a combination of exact diagonalization and the composite fermion theory shows that the ground state is fully spin polarized and supports a robust spin wave mode even in the limit of vanishing Zeeman coupling. Thus, even though composite fermions are formed, a mean field description that treats them as weakly interacting particles breaks down, and the exchange interaction between them is strong enough to cause a qualitative change in the behavior by inducing full spin polarization. We also find that the fully spin polarized composite fermion Fermi sea has lower energy than the paired Pfaffian state at the relevant half fillings. Award No. DE-SC0005042 (ACB, JKJ), Hungarian Scientific Research Funds No. K105149 (CT), the Polish NCN Grant 2014/14/A/ST3/00654 and the EU Marie Curie Grant PCIG09-GA-2011-294186 (AW).

  8. Landau Level Splittings, Phase Transitions, and Nonuniform Charge Distribution in Trilayer Graphene.

    PubMed

    Campos, Leonardo C; Taychatanapat, Thiti; Serbyn, Maksym; Surakitbovorn, Kawin; Watanabe, Kenji; Taniguchi, Takashi; Abanin, Dmitry A; Jarillo-Herrero, Pablo

    2016-08-01

    We report on magnetotransport studies of dual-gated, Bernal-stacked trilayer graphene (TLG) encapsulated in boron nitride crystals. We observe a quantum Hall effect staircase which indicates a complete lifting of the 12-fold degeneracy of the zeroth Landau level. As a function of perpendicular electric field, our data exhibit a sequence of phase transitions between all integer quantum Hall states in the filling factor interval -8<ν<0. We develop a theoretical model and argue that, in contrast to monolayer and bilayer graphene, the observed Landau level splittings and quantum Hall phase transitions can be understood within a single-particle picture, but imply the presence of a charge density imbalance between the inner and outer layers of TLG, even at charge neutrality and zero transverse electric field. Our results indicate the importance of a previously unaccounted band structure parameter which, together with a more accurate estimate of the other tight-binding parameters, results in a significantly improved determination of the electronic and Landau level structure of TLG. PMID:27541472

  9. Spatially resolving unconventional interface Landau quantization in a graphene monolayer-bilayer planar junction

    NASA Astrophysics Data System (ADS)

    Yan, Wei; Li, Si-Yu; Yin, Long-Jing; Qiao, Jia-Bin; Nie, Jia-Cai; He, Lin

    2016-05-01

    Hybrid quantum Hall (QH) junctions have been extensively studied by transport measurements due to their exciting physics and device applications. Here we report on spatially resolving electronic properties of such a junction on the nanoscale. We present a subnanometer-resolved scanning tunneling microscopy (STM) and scanning tunneling spectroscopy study of a monolayer-bilayer graphene planar junction in the QH regime. The atomically well-defined interface of such a junction allows us to spatially resolve the interface electronic properties. Around the interface, we detect Landau quantization of massless Dirac fermions as expected in the graphene monolayer for filled states of the junction, whereas unexpectedly, only Landau quantization of massive Dirac fermions as expected in the graphene bilayer is observed for empty states. The observed unconventional interface Landau quantization arises from the fact that the quantum conductance across the interface is solely determined by the minimum filling factors (number of edge modes) in the graphene monolayer and bilayer regions of the junction. Our finding opens the way to spatially explore the QH effect of different graphene hybrid structures only using a STM.

  10. Energy spectrum and Landau levels in bilayer graphene with spin-orbit interaction

    NASA Astrophysics Data System (ADS)

    Mireles, Francisco; Schliemann, John

    2012-09-01

    We present a theoretical study of the band structure and Landau levels in bilayer graphene at low energies in the presence of a transverse magnetic field and Rashba spin-orbit interaction in the regime of negligible trigonal distortion. Within an effective low-energy approach the (Löwdin partitioning theory), we derive an effective Hamiltonian for bilayer graphene that incorporates the influence of the Zeeman effect, the Rashba spin-orbit interaction and, inclusively, the role of the intrinsic spin-orbit interaction on the same footing. Particular attention is paid to the energy spectrum and Landau levels. Our modeling unveils the strong influence of the Rashba coupling λR in the spin splitting of the electron and hole bands. Graphene bilayers with weak Rashba spin-orbit interaction show a spin splitting linear in momentum and proportional to λR, but scaling inversely proportional to the interlayer hopping energy γ1. However, at robust spin-orbit coupling λR, the energy spectrum shows a strong warping behavior near the Dirac points. We find that the bias-induced gap in bilayer graphene decreases with increasing Rashba coupling, a behavior resembling a topological insulator transition. We further predict an unexpected asymmetric spin splitting and crossings of the Landau levels due to the interplay between the Rashba interaction and the external bias voltage. Our results are of relevance for interpreting magnetotransport and infrared cyclotron resonance measurements, including situations of comparatively weak spin-orbit coupling.

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

    PubMed

    Biswas, Rudro R; Son, Dam Thanh

    2016-08-01

    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. PMID:27436906

  12. Exploring Replica-Exchange Wang-Landau sampling in higher-dimensional parameter space

    SciTech Connect

    Valentim, Alexandra; Rocha, Julio C. S.; Tsai, Shan-Ho; Li, Ying Wai; Eisenbach, Markus; Fiore, Carlos E; Landau, David P

    2015-01-01

    We considered a higher-dimensional extension for the replica-exchange Wang-Landau algorithm to perform a random walk in the energy and magnetization space of the two-dimensional Ising model. This hybrid scheme combines the advantages of Wang-Landau and Replica-Exchange algorithms, and the one-dimensional version of this approach has been shown to be very efficient and to scale well, up to several thousands of computing cores. This approach allows us to split the parameter space of the system to be simulated into several pieces and still perform a random walk over the entire parameter range, ensuring the ergodicity of the simulation. Previous work, in which a similar scheme of parallel simulation was implemented without using replica exchange and with a different way to combine the result from the pieces, led to discontinuities in the final density of states over the entire range of parameters. From our simulations, it appears that the replica-exchange Wang-Landau algorithm is able to overcome this diculty, allowing exploration of higher parameter phase space by keeping track of the joint density of states.

  13. Gapped excitations of unconventional fractional quantum Hall effect states in the second Landau level

    NASA Astrophysics Data System (ADS)

    Wurstbauer, U.; Levy, A. L.; Pinczuk, A.; West, K. W.; Pfeiffer, L. N.; Manfra, M. J.; Gardner, G. C.; Watson, J. D.

    2015-12-01

    We report the observation of low-lying collective charge and spin excitations in the second Landau level at ν =2 +1 /3 and also for the very fragile states at ν =2 +2 /5 and 2 +3 /8 in inelastic light scattering experiments. These modes exhibit a clear dependence on filling factor and temperature substantiating the unique access to the characteristic neutral excitation spectra of the incompressible fractional quantum Hall effect (FQHE) states. A detailed mode analysis reveals low-energy modes at around 70 μ eV and a sharp mode slightly below the Zeeman energy interpreted as gap and spin-wave excitation, respectively. The lowest-energy collective charge excitation spectrum at ν =2 +1 /3 exhibits significant qualitative similarities with its cousin state in the lowest Landau level at ν =1 /3 suggesting similar magnetoroton minima in the neutral excitations. The mode energies differ by a scaling of 0.15 indicating different interaction physics in the N =0 and N =1 Landau levels. The striking polarization dependence in elastic and inelastic light scattering is discussed in the framework of anisotropic electron phases that allow for the stabilization of nematic FQHE states. The observed excitation spectra provide new insights by accessing quantum phases in the bulk of electron systems and facilitate comparison with different theoretical descriptions of those enigmatic FQHE states.

  14. Demonstration of Geometric Landau-Zener Interferometry in a Superconducting Phase Qubit

    NASA Astrophysics Data System (ADS)

    Yu, Yang; Tan, Xinsheng; Zhang, Zhentao; Zhu, Shiliang; Zhang, Danwei; Han, Siyuan

    2014-03-01

    Geometric quantum manipulation and Landau-Zener interferometry have been separately explored in many quantum systems. Here we fill this gap by combining these two approaches in the study of the dynamics of a superconducting phase qubit. We propose and then experimentally demonstrate Landau-Zener interferometry based on pure geometric phases in this solid-state qubit. We observe the interference due to geometric phases accumulated in the evolution between two consecutive Landau-Zener transitions, while the dynamical phase is eliminated by a spin-echo pulse. Our numerical simulation results using measured energy relaxation and dephasing times agree well with the experimental results. The full controllability of the qubit population as a function of intrinsically fault-tolerant geometric phases provides a promising approach to fault-tolerant quantum computation. This work is partially supported by the SKPBR of China (2011CB922104, 2011CBA00200), NSFC (91021003, 11274156,11125417), PAPD, and the PCSIRT. Han is supported in part by NSF of United States (PHY-1314861).

  15. Das Neutron, der Kosmos und die Kräfte: Neutronen in der Teilchenphysik

    NASA Astrophysics Data System (ADS)

    Soldner, Torsten

    2003-05-01

    Das Neutron besitzt eine einzigartige Kombination von Eigenschaften. Sie ermöglicht die Untersuchung aller vier elementaren Kräfte. Dabei wurden beeindruckende Resultate erzielt, wie die Präzisionsmessungen der elektrischen Ladung des Neutrons oder der Feinstrukturkonstante zeigen. Die genaue Bestimmung der schwachen Wechselwirkungsstärke der Nukleonen liefert der Astrophysik wichtige Daten. Die Messung eines von Null verschiedenen elektrischen Dipolmoments des Neutrons könnte einen entscheidenden Hinweis über die Physik jenseits des Standardmodells der Teilchenphysik geben. Doch auch zur Aufklärung von Unsicherheiten innerhalb des Standardmodells selbst tragen Neutronen bei.

  16. Verbesserung der Prozessbedingungen beim Einlippentiefbohren durch unterschiedliche Formen der Vorschubmodulation

    NASA Astrophysics Data System (ADS)

    Eisseler, Rocco

    Das Tiefbohren mit Einlippenwerkzeugen ist bei vielen Anwendungen das Verfahren der ersten Wahl, vor allem wenn kleine und kleinste Bohrungsdurchmesser, ein sehr großes Verhältnis zwischen Bohrtiefe und Durchmesser (l/D) und eine hohe Bearbeitungsqualität gefordert werden. Der erreichbare Durchmesserbereich des Verfahrens liegt zwischen D = 0,5 mm und 40 mm, wobei die möglichen Bohrtiefen von l = 3 x D bis 250 x D reichen. Diese Werte beziehen sich auf das Vollbohren, beim Aufbohren können noch größere Durchmesser erreicht werden [1]. Die erreichbare Oberflächenqualität ist so hoch, dass in den meisten Fällen auf eine nachfolgende Feinbearbeitung verzichtet werden kann.

  17. Aufgaben und Genauigkeit der klinischen Dosimetrie

    NASA Astrophysics Data System (ADS)

    Krieger, Hanno

    In diesem Kapitel werden die Aufgaben der klinischen Dosimetrie für die verschiedenen radiologischen Disziplinen zusammengestellt. Die wichtigste Aufgabe ist die Messung der im bestrahlten Medium entstandenen Energiedosis für die verschiedenen Strahlungsquellen. Die am weitesten verbreitete dazu verwendete Methode ist die Dosismessung mit gasgefüllten Ionisationskammern. Im zweiten Teil des Kapitels werden die Genauigkeitsanforderungen der klinischen Dosimetrie diskutiert.

  18. Friedrich Möglich - sein Beitrag zum Aufbau der Physik in der DDR. Friedrich Möglich - langjähriger Mitherausgeber und Chefredakteur der Annalen der Physik

    NASA Astrophysics Data System (ADS)

    Rompe, Robert

    Friedrich Möglich, ein Schüler von Max von Laue und Erwin Schrödinger, übernahm 1947 die Chefredaktion der Annalen der Physik.Translated AbstractFriedrich Möglich - His Contributions to the Formation of Physics in GDRFriedrich Möglich a student of Max von Laue and Erwin Schrödinger took over as editor in chief of Annalen der Physik in 1947.

  19. Tycho Brahe - Instrumentenbauer und Meister der Beobachtungstechnik

    NASA Astrophysics Data System (ADS)

    Wolfschmidt, Gudrun

    Vor der Erfindung des Fernrohrs war der dänische Astronom Tycho Brahe (1546 - 1601) der bedeutendste beobachtende Astronom. Von seinem Observatorium Uraniborg auf der - damals dänischen - Insel Hven ist heute noch der Grundriß erkennbar, von Stjerneborg sind die Fundamente erhalten, die Kuppeln in den 1950er Jahren ergänzt. In der Astronomie-Ausstellung im Deutschen Museum gibt es ein Modell der Sternwarte Uraniborg und der zugehörigen Instrumente (Maßstab 1:10); das größere Modell wurde dem Technischen Museum in Malmö geschenkt. Die Instrumente, die er in den Observatorien Uraniborg und Stjerneborg benutzte, sind nicht erhalten. Aber es gibt gute Beschreibungen der Instrumente (Halbkreis, Quadranten, Sextanten, Armillarsphären, Triquetrum, Himmelsglobus) in seinem Buch Astronomiae instauratae mechanica (Wandsbek 1598). Eine Nachbildung des großen hölzernen Quadranten kann man im Runden Turm in Kopenhagen sehen. Zwei Sextanten, hergestellt für Tycho um 1600 von Jost Bürgi und Erasmus Habermel, gibt es noch im Nationalmuseum für Technik in Prag. Ähnlichkeiten von Tychos Instrumenten mit Groß-Instrumenten aus dem islamischen Kulturkreis sind auffällig. Tycho Brahes Meßgeräte markieren einen großen Fortschritt in der Entwicklung astronomischer Instrumente und Meßtechniken und bilden die Grundlage für den weiteren Fortschritt der Positionsastronomie und der damit verbundenen Tabellenwerke. Die Nachwirkungen sind bis ins 17. und 18. Jahrhundert nachweisbar.

  20. Untersuchung der Richtwirkung der Einkopplung von ebenen Wellen in eine Leitung

    NASA Astrophysics Data System (ADS)

    Magdowski, M.; Vick, R.

    2013-07-01

    Elektrische Leitungen und Kabel stellen häufig die Haupteinfallstore für elektromagnetische Felder in die daran angeschlossenen Geräte und Systeme dar. Für die Einkopplung einer ebenen Welle kann der in eine Leitung eingekoppelte Strom unter bestimmten Voraussetzungen mit Hilfe der Leitungstheorie sehr effizient bestimmt werden. Er hängt dabei von den Abmessungen der Leitung, den Leitungsabschlüssen sowie der Amplitude, der Wellenlänge und der Einfallsrichtung der ebenen Welle ab. In dieser Arbeit wird die Abhängigkeit der Einkopplung von der Einfallsrichtung näher untersucht. Dazu werden Richtdiagramme der Einkopplung berechnet, dargestellt und hinsichtlich der mittleren und maximalen Einkopplung über alle Einfallsrichtungen und Polarisationen ausgewertet. Die Ergebnisse werden genutzt, um die maximale Direktivität der Einkopplung in eine Leitung zu bestimmen. Fasst man die Einkopplung externer Felder in eine Leitung als einen Störfestigkeitstest auf, so kann die maximale Direktivität benutzt werden, um einen Vergleich zwischen unterschiedlichen Messumgebungen wie Absorberhallen und Modenverwirbelungskammern herzustellen.

  1. Von Humboldt bis Einstein. Berlin als Weltzentrum der exakten Wissenschaften.

    NASA Astrophysics Data System (ADS)

    Meschkowski, H.

    Contents: 1. Die Anfänge. 2. Die Ära Dirichlet-Jacobi. 3. Der Ausbau der experimentellen Naturwissenschaften. 4. Alexander von Humboldt. 5. Berlin wird "Weltzentrum" der Mathematik. 6. Die Ära Helmholtz. 7. Neue Arbeitsweisen der Astronomie. 8. Chemie: Forschung und Industrie. 9. Max Planck. 10. Ins technische Zeitalter. 11. Zur Mathematik der zwanziger Jahre. 12. Albert Einstein. 13. Fortschritte der Grundlagenforschung. 14. Erwin Schrödinger: Physiker, Philosoph und Poet. 15. Zum Schluß.

  2. A comparative study of the reentrant integer quantum Hall states in the second and third Landau levels

    NASA Astrophysics Data System (ADS)

    Deng, Nianpei; Watson, John; Manfra, Michael; Csathy, Gabor

    2012-02-01

    In the two-dimensional electron gas competing electron-electron interactions and disorder effects give rise to many-body ground states such as the fractional quantum Hall and the reentrant integer quantum Hall states (RIQHS). The latter are not yet well understood, but they are believed to be Wigner crystal-like electron solids with one or more electrons at each lattice nodes. We have recently shown that for the RIQHS in the second Landau level one can extract their onset temperature from the temperature-dependent magnetoresistance. We report similar studies of the RIQHS in the third Landau level. To our surprise, the onset temperatures of the RIQHSs in the third Landau level are about a factor of 3 larger than those in the second Landau level. This result clearly shows that the RIQHSs in the second and third Landau level have vastly different cohesion energies and may indicate different internal symmetries for these states. This work was supported by the DOE grant DE-SC0006671.

  3. Electron collisions in the trapped gyro-Landau fluid transport model

    NASA Astrophysics Data System (ADS)

    Staebler, G. M.; Kinsey, J. E.

    2010-12-01

    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.

  4. Electron collisions in the trapped gyro-Landau fluid transport model

    SciTech Connect

    Staebler, G. M.; Kinsey, J. E.

    2010-12-15

    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.

  5. Incompatibility of Time-Dependent Bogoliubov-de-Gennes and Ginzburg-Landau Equations

    NASA Astrophysics Data System (ADS)

    Frank, Rupert L.; Hainzl, Christian; Schlein, Benjamin; Seiringer, Robert

    2016-07-01

    We study the time-dependent Bogoliubov-de-Gennes equations for generic translation-invariant fermionic many-body systems. For initial states that are close to thermal equilibrium states at temperatures near the critical temperature, we show that the magnitude of the order parameter stays approximately constant in time and, in particular, does not follow a time-dependent Ginzburg-Landau equation, which is often employed as a phenomenological description and predicts a decay of the order parameter in time. The full non-linear structure of the equations is necessary to understand this behavior.

  6. Generalization of the Landau-Lifshitz-Gilbert equation for conducting ferromagnets.

    PubMed

    Zhang, Shufeng; Zhang, Steven S-L

    2009-02-27

    We propose an extension of the Landau-Lifshitz-Gilbert (LLG) equation by explicitly including the role of conduction electrons in magnetization dynamics of conducting ferromagnets. The temporal and spatial dependent magnetization order parameter m(r,t) generates both electrical and spin currents that provide dissipation of the energy and angular momentum of the processing magnet. The resulting LLG equation contains highly spatial dependence of damping term and thus micromagnetic simulations based on the standard LLG equation should be reexamined for magnetization dynamics involving narrow domain walls and spin waves with short wavelengths. PMID:19257763

  7. Numerical integration of the stochastic Landau-Lifshitz-Gilbert equation in generic time-discretization schemes.

    PubMed

    Romá, Federico; Cugliandolo, Leticia F; Lozano, Gustavo S

    2014-08-01

    We introduce a numerical method to integrate the stochastic Landau-Lifshitz-Gilbert equation in spherical coordinates for generic discretization schemes. This method conserves the magnetization modulus and ensures the approach to equilibrium under the expected conditions. We test the algorithm on a benchmark problem: the dynamics of a uniformly magnetized ellipsoid. We investigate the influence of various parameters, and in particular, we analyze the efficiency of the numerical integration, in terms of the number of steps needed to reach a chosen long time with a given accuracy. PMID:25215839

  8. Higher charges and regularized quantum trace identities in su(1,1) Landau-Lifshitz model

    SciTech Connect

    Melikyan, A.; Pinzul, A.; Weber, G.

    2010-12-15

    We solve the operator ordering problem for the quantum continuous integrable su(1,1) Landau-Lifshitz model, and give a prescription to obtain the quantum trace identities, and the spectrum for the higher-order local charges. We also show that this method, based on operator regularization and renormalization, which guarantees quantum integrability, as well as the construction of self-adjoint extensions, can be used as an alternative to the discretization procedure, and unlike the latter, is based only on integrable representations.

  9. Generalization of the Landau-Lifshitz-Gilbert Equation for Conducting Ferromagnets

    NASA Astrophysics Data System (ADS)

    Zhang, Shufeng; Zhang, Steven S.-L.

    2009-02-01

    We propose an extension of the Landau-Lifshitz-Gilbert (LLG) equation by explicitly including the role of conduction electrons in magnetization dynamics of conducting ferromagnets. The temporal and spatial dependent magnetization order parameter m(r,t) generates both electrical and spin currents that provide dissipation of the energy and angular momentum of the processing magnet. The resulting LLG equation contains highly spatial dependence of damping term and thus micromagnetic simulations based on the standard LLG equation should be reexamined for magnetization dynamics involving narrow domain walls and spin waves with short wavelengths.

  10. Incompatibility of Time-Dependent Bogoliubov-de-Gennes and Ginzburg-Landau Equations

    NASA Astrophysics Data System (ADS)

    Frank, Rupert L.; Hainzl, Christian; Schlein, Benjamin; Seiringer, Robert

    2016-05-01

    We study the time-dependent Bogoliubov-de-Gennes equations for generic translation-invariant fermionic many-body systems. For initial states that are close to thermal equilibrium states at temperatures near the critical temperature, we show that the magnitude of the order parameter stays approximately constant in time and, in particular, does not follow a time-dependent Ginzburg-Landau equation, which is often employed as a phenomenological description and predicts a decay of the order parameter in time. The full non-linear structure of the equations is necessary to understand this behavior.

  11. Landau damping of ion acoustic wave in Lorentzian multi-ion plasmas

    SciTech Connect

    Arshad, Kashif; Mahmood, S.; Mirza, Arshad M.

    2011-09-15

    The Landau damping rates of ion acoustic wave are studied by using Vlasov-Poisson model for unmagnetized Lorentzian or kappa distributed plasma containing electrons, positively and negatively charged ions. It is found that the damping rate of ion acoustic wave is increased with the decrease of kappa (i.e., the spectral index of Lorentzian distribution) value. The damping rates of the electrostatic wave in multi-ion component plasmas are discussed in detail which depends on electron to ion temperature ratio and ions masses and density ratios. The numerical results are also shown by choosing some typical experimental parameters of multi-ion plasmas.

  12. Protein folding of the H0P model: A parallel Wang-Landau study

    SciTech Connect

    Shi, Guangjie; Wuest, Thomas; Li, Ying Wai; Landau, David P

    2015-01-01

    We propose a simple modication to the hydrophobic-polar (HP) protein model, by introducing a new type of monomer, "0", with intermediate hydrophobicity of some amino acids between H and P. With the replica-exchange Wang-Landau sampling method, we investigate some widely studied HP sequences as well as their H0P counterparts and observe that the H0P sequences exhibit dramatically reduced ground state degeneracy and more signicant transition signals at low temperature for some thermodynamic properties, such as the specific heat.

  13. Gate-Tunable Landau Level Filling and Spectroscopy in Coupled Massive and Massless Electron Systems

    NASA Astrophysics Data System (ADS)

    Cheng, Bin; Wu, Yong; Wang, Peng; Pan, Cheng; Taniguchi, T.; Watanabe, K.; Bockrath, M.

    2016-07-01

    We report transport studies on coupled massive and massless electron systems, realized using twisted monolayer-graphene-natural bilayer-graphene stacks. We incorporate the layers in a dual-gated transistor geometry enabling independently tuning their charge density and the perpendicular electric field. In a perpendicular magnetic field, we observe a distinct pattern of gate-tunable Landau level crossings. Screening and interlayer electron-electron interactions yield a nonlinear monolayer gate capacitance. Data analysis enables determination of the monolayer's Fermi velocity and the bilayer's effective mass. The mass obtained is larger than that expected for isolated bilayers, suggesting that the interlayer interactions renormalize the band structure.

  14. Protein folding of the HOP model: A parallel Wang—Landau study

    NASA Astrophysics Data System (ADS)

    Shi, G.; Wüst, T.; Li, Y. W.; Landau, D. P.

    2015-09-01

    We propose a simple modification to the hydrophobic-polar (HP) protein model, by introducing a new type of monomer, “0”, with intermediate hydrophobicity of some amino acids between H and P. With the replica-exchange Wang-Landau sampling method, we investigate some widely studied HP sequences as well as their H0P counterparts and observe that the H0P sequences exhibit dramatically reduced ground state degeneracy and more significant transition signals at low temperature for some thermodynamic properties, such as the specific heat.

  15. A Landau-de Gennes theory for hard colloidal rods: Defects and tactoids.

    PubMed

    Everts, J C; Punter, M T J J M; Samin, S; van der Schoot, P; van Roij, R

    2016-05-21

    We construct a phenomenological Landau-de Gennes theory for hard colloidal rods by performing an order parameter expansion of the chemical-potential dependent grand potential. By fitting the coefficients to known results of Onsager theory, we are not only able to describe the isotropic-nematic phase transition as function of density, including the well-known density jump, but also the isotropic-nematic planar interface. The resulting theory is applied in calculations of the isotropic core size in a radial hedgehog defect, the density dependence of linear defects of hard rods in square confinement, and the formation of a nematic droplet in an isotropic background. PMID:27208968

  16. On the Infrared Behaviour of Landau Gauge Yang-Mills Theory with Differently Charged Scalar Fields

    SciTech Connect

    Alkofer, Reinhard; Maas, Axel; Macher, Veronika; Fister, Leonard

    2011-05-23

    Recently it has been argued that infrared singularities of the quark-gluon vertex of Landau gauge QCD can confine static quarks via a linear potential. It is demonstrated that the same mechanism also may confine fundamental scalar fields. This opens the possibility that within functional approaches static confinement is an universal property of the gauge sector even though it is formally represented in the functional equations of the matter sector. The colour structure of Dyson-Schwinger equations for fundamental and adjoint scalar fields is determined for the gauge groups SU(N) and G(2) exhibiting interesting cancellations purely due to colour algebra.

  17. Generalized Ginzburg-Landau approach to inhomogeneous phases in nonlocal chiral quark models

    NASA Astrophysics Data System (ADS)

    Carlomagno, J. P.; Gómez Dumm, D.; Scoccola, N. N.

    2015-05-01

    We analyze the presence of inhomogeneous phases in the QCD phase diagram within the framework of nonlocal chiral quark models. We concentrate in particular in the positions of the tricritical (TCP) and Lifshitz (LP) points, which are studied in a general context using a generalized Ginzburg-Landau approach. We find that for all the phenomenologically acceptable model parametrizations considered the TCP is located at a higher temperature and a lower chemical potential in comparison with the LP. Consequently, these models seem to favor a scenario in which the onset of the first order transition between homogeneous phases is not covered by an inhomogeneous, energetically favored phase.

  18. Longwave oscillatory patterns in liquids: outside the world of the complex Ginzburg-Landau equation

    NASA Astrophysics Data System (ADS)

    Nepomnyashchy, Alexander; Shklyaev, Sergey

    2016-02-01

    The main subject of the present review is longwave oscillatory patterns in systems with conservation laws, that cannot be described by the complex Ginzburg-Landau equation. As basic examples, we consider nonlinear patterns created by Marangoni and buoyancy instabilities in pure and binary liquids, where the longwave nature of instabilities is related to conservation of the liquid volume, conservation of mass or approximate conservation of the mean temperature. Also, we discuss the excitation of longwave instabilities by a time-periodic parameter modulation.

  19. Higher charges and regularized quantum trace identities in su(1,1) Landau-Lifshitz model

    NASA Astrophysics Data System (ADS)

    Melikyan, A.; Pinzul, A.; Weber, G.

    2010-12-01

    We solve the operator ordering problem for the quantum continuous integrable su(1,1) Landau-Lifshitz model, and give a prescription to obtain the quantum trace identities, and the spectrum for the higher-order local charges. We also show that this method, based on operator regularization and renormalization, which guarantees quantum integrability, as well as the construction of self-adjoint extensions, can be used as an alternative to the discretization procedure, and unlike the latter, is based only on integrable representations.

  20. Tailoring population inversion in Landau-Zener-Stückelberg interferometry of flux qubits.

    PubMed

    Ferrón, Alejandro; Domínguez, Daniel; Sánchez, María José

    2012-12-01

    We distinguish different mechanisms for population inversion in flux qubits driven by dc+ac magnetic fields. We show that for driving amplitudes such that there are Landau-Zener-Stückelberg interferences, it is possible to have population inversion solely mediated by the environmental bath. Furthermore, we find that the degree of population inversion can be controlled by tailoring a resonant frequency Ω(p) in the environmental bath. To observe these effects experiments should be performed for long driving times after full relaxation. PMID:23368247

  1. Distribution of Chern number by Landau level broadening in Hofstadter butterfly

    NASA Astrophysics Data System (ADS)

    Yoshioka, Nobuyuki; Matsuura, Hiroyasu; Ogata, Masao

    2015-04-01

    We discuss the relationship between the quantum Hall conductance and a fractal energy band structure, Hofstadter butterfly, on a square lattice under a magnetic field. At first, we calculate the Hall conductance of Hofstadter butterfly on the basis of the linear responce theory. By classifying the bands into some groups with a help of continued fraction expansion, we find that the conductance at the band gaps between the groups accord with the denominators of fractions obtained by aborting the expansion halfway. The broadening of Landau levels is given as an account of this correspondance.

  2. Wang-Landau Algorithm for Continuous Models and Joint Density of States

    SciTech Connect

    Zhou, Chenggang; Schulthess, Thomas C; Torbrugge, S.; Landau, D. P.

    2006-01-01

    We present a modified Wang-Landau algorithm for models with continuous degrees of freedom. We demonstrate this algorithm with the calculation of the joint density of states of ferromagnet Heisenberg models and a model polymer chain. The joint density of states contains more information than the density of states of a single variable-energy, but is also much more time consuming to calculate. We present strategies to significantly speed up this calculation for large systems over a large range of energy and order parameter.

  3. Noise-induced synchronization of spatiotemporal chaos in the Ginzburg-Landau equation

    NASA Astrophysics Data System (ADS)

    Koronovskiĭ, A. A.; Popov, P. V.; Hramov, A. E.

    2008-11-01

    We have studied noise-induced synchronization in a distributed autooscillatory system described by the Ginzburg-Landau equations, which occur in a regime of chaotic spatiotemporal oscillations. A new regime of synchronous behavior, called incomplete noise-induced synchronization (INIS), is revealed, which can arise only in spatially distributed systems. The mechanism leading to the development of INIS in a distributed medium under the action of a distributed source of noise is analytically described. Good coincidence of analytical and numerical results is demonstrated.

  4. Particle multiplicity distributions: Connections with a Feynman-Wilson gas and a Ginzburg-Landau theory

    NASA Astrophysics Data System (ADS)

    Mekjian, A. Z.

    2002-01-01

    Particle yields and fluctuations are studied in a general framework based on a cycle class picture in a Feynman path integral approach. Various cases such as the disoriented chiral condensate distribution, a negative binomial distribution, partially coherent state emission, and field emission from Lorentzian line shapes are discussed. Generalizations based on these important specific cases are developed. Connections of the cycle class picture with other approaches based on combinants, cumulants, hierarchical models, and clan variables are presented for the specific and general cases. A relation to a Feynman-Wilson gas and to the Ginzburg-Landau model are discussed.

  5. Suppression of stimulated brillouin scattering by increased landau damping in multiple-ion-species hohlraum plasmas.

    PubMed

    Neumayer, P; Berger, R L; Divol, L; Froula, D H; London, R A; Macgowan, B J; Meezan, N B; Ross, J S; Sorce, C; Suter, L J; Glenzer, S H

    2008-03-14

    We demonstrate that multiple-ion-species plasmas greatly reduce stimulated Brillouin scattering (SBS) in high-electron temperature inertial confinement fusion hohlraums. Landau damping is increased by adding hydrogen to a CO(2) gas filled hohlraum. We find that the SBS reflectivity decreases monotonically with increasing hydrogen fraction from 18% to 3% with a simultaneous increase of laser beam transmission. Detailed simulations with a 3D laser-plasma interaction code are in agreement with the experimentally observed reduction in backscattered light. PMID:18352195

  6. Inferring the time-dependent complex Ginzburg-Landau equation from modulus data

    SciTech Connect

    Yu, Rotha P.; Paganin, David M.; Morgan, Michael J.

    2005-11-01

    We present a formalism for inferring the equation of evolution of a complex wave field that is known to obey an otherwise unspecified (2+1)-dimensional time-dependent complex Ginzburg-Landau equation, given field moduli over various closely spaced planes. The phase of the complex wave field is retrieved via a noninterferometric method, and all terms in the equation of evolution are determined using only the magnitude of the complex wave field. The formalism is tested using simulated data for a generalized nonlinear system with a single-component complex wave field. The method can be generalized to multicomponent complex fields.

  7. Noise-induced synchronization of spatiotemporal chaos in the Ginzburg-Landau equation

    SciTech Connect

    Koronovskii, A. A.; Popov, P. V.; Hramov, A. E.

    2008-11-15

    We have studied noise-induced synchronization in a distributed autooscillatory system described by the Ginzburg-Landau equations, which occur in a regime of chaotic spatiotemporal oscillations. A new regime of synchronous behavior, called incomplete noise-induced synchronization (INIS), is revealed, which can arise only in spatially distributed systems. The mechanism leading to the development of INIS in a distributed medium under the action of a distributed source of noise is analytically described. Good coincidence of analytical and numerical results is demonstrated.

  8. Stable and fast semi-implicit integration of the stochastic Landau-Lifshitz equation.

    PubMed

    Mentink, J H; Tretyakov, M V; Fasolino, A; Katsnelson, M I; Rasing, Th

    2010-05-01

    We propose new semi-implicit numerical methods for the integration of the stochastic Landau-Lifshitz equation with built-in angular momentum conservation. The performance of the proposed integrators is tested on the 1D Heisenberg chain. For this system, our schemes show better stability properties and allow us to use considerably larger time steps than standard explicit methods. At the same time, these semi-implicit schemes are also of comparable accuracy to and computationally much cheaper than the standard midpoint implicit method. The results are of key importance for atomistic spin dynamics simulations and the study of spin dynamics beyond the macro spin approximation. PMID:21393676

  9. Gate-Tunable Landau Level Filling and Spectroscopy in Coupled Massive and Massless Electron Systems.

    PubMed

    Cheng, Bin; Wu, Yong; Wang, Peng; Pan, Cheng; Taniguchi, T; Watanabe, K; Bockrath, M

    2016-07-01

    We report transport studies on coupled massive and massless electron systems, realized using twisted monolayer-graphene-natural bilayer-graphene stacks. We incorporate the layers in a dual-gated transistor geometry enabling independently tuning their charge density and the perpendicular electric field. In a perpendicular magnetic field, we observe a distinct pattern of gate-tunable Landau level crossings. Screening and interlayer electron-electron interactions yield a nonlinear monolayer gate capacitance. Data analysis enables determination of the monolayer's Fermi velocity and the bilayer's effective mass. The mass obtained is larger than that expected for isolated bilayers, suggesting that the interlayer interactions renormalize the band structure. PMID:27447518

  10. Characterization of qubit dephasing by Landau-Zener-Stückelberg-Majorana interferometry.

    PubMed

    Forster, F; Petersen, G; Manus, S; Hänggi, P; Schuh, D; Wegscheider, W; Kohler, S; Ludwig, S

    2014-03-21

    Controlling coherent interaction at avoided crossings and the dynamics there is at the heart of quantum information processing. A particularly intriguing dynamics is observed in the Landau-Zener regime, where periodic passages through the avoided crossing result in an interference pattern carrying information about qubit properties. In this Letter, we demonstrate a straightforward method, based on steady-state experiments, to obtain all relevant information about a qubit, including complex environmental influences. We use a two-electron charge qubit defined in a lateral double quantum dot as test system and demonstrate a long coherence time of T2 ≃ 200 ns, which is limited by electron-phonon interaction. PMID:24702402

  11. Atomic Landau-Zener Tunneling in Fourier-Synthesized Optical Lattices

    SciTech Connect

    Salger, Tobias; Geckeler, Carsten; Kling, Sebastian; Weitz, Martin

    2007-11-09

    We report on an experimental study of quantum transport of atoms in variable periodic optical potentials. The band structure of both ratchet-type asymmetric and symmetric lattice potentials is explored. The variable atom potential is realized by superimposing a conventional standing wave potential of {lambda}/2 spatial periodicity with a fourth-order multiphoton potential of {lambda}/4 periodicity. We find that the Landau-Zener tunneling rate between the first and the second excited Bloch band depends critically on the relative phase between the two spatial lattice harmonics.

  12. Landau-Zener Effect In The Time-Dependent Hartree-Fock-Bogoliubov Equations

    SciTech Connect

    Mirea, M.

    2008-01-24

    If the Hartree-Fock-Bogoliubov equations of motion are solved in the case of seniority one nuclear systems, the unpaired nucleon remains on the same orbital. The blocking effect hinders the possibility that the unpaired nucleon skips from one orbital to another. A new set of coupled channel equations based on the time dependent Hartree-Fock-Bogoliubov formalism is deduced. This system includes a mechanism similar to the Landau-Zener effect, allowing that the unpaired nucleon jumps from one level to another.

  13. Exact transition probabilities in a 6-state Landau-Zener system with path interference

    NASA Astrophysics Data System (ADS)

    Sinitsyn, N. A.

    2015-05-01

    We identify a nontrivial multistate Landau-Zener (LZ) model for which transition probabilities between any pair of diabatic states can be determined analytically and exactly. In the semiclassical picture, this model features the possibility of interference of different trajectories that connect the same initial and final states. Hence, transition probabilities are generally not described by the incoherent successive application of the LZ formula. We discuss reasons for integrability of this system and provide numerical tests of the suggested expression for the transition probability matrix.

  14. Statistics of heat generated in a solvable dissipative Landau-Zener model

    NASA Astrophysics Data System (ADS)

    Ponomarenko, V. V.

    2015-07-01

    We consider an adiabatic Landau-Zener model of a two-level system diagonally coupled to an Ohmic bosonic bath of large spectral width and, through fermionization, derive its exact solution at a special value of the coupling constant. From this solution we obtain the characteristic function of the distribution of energy transferred to the bath during the evolution of the system ground state as a functional determinant of a single-particle operator. At zero temperature this distribution is further found to be exponential, and at finite temperature the first three moments of the distribution are calculated.

  15. Topological Landau-Ginzburg model of two-dimensional string theory

    NASA Astrophysics Data System (ADS)

    Ghoshal, Debashis; Mukhi, Sunil

    1994-08-01

    We study a topological Landau-Ginzburg model with superpotential W( X) = X-1. This is argued to be equivalent to c = 1 string theory compactified at the self-dual radius. We compute the tree-level correlation function of N tachyons in this theory and show their agreement with matrix-model results. We also discuss the nature of contract terms, the perturbed superpotential and the flow of operators in the small phase space. The role of gravitational descendants in this theory is examined, and the tachyon two-point function in genus 1 is obtained using a conjectured modification of the gravitational recursion relations.

  16. Landau-Yang theorem and decays of a Z' boson into two Z bosons.

    PubMed

    Keung, Wai-Yee; Low, Ian; Shu, Jing

    2008-08-29

    We study the decay of a Z' boson into two Z bosons by extending the Landau-Yang theorem to a parent particle decaying into two Z bosons. For a spin-1 parent the theorem predicts that (1) there are only two possible couplings and (2) the normalized differential cross section depends on kinematics only through a phase shift in the azimuthal angle between the two decay planes of the Z boson. When the parent is a Z' the two possible couplings are anomaly induced and CP violating, respectively. At the CERN Large Hadron Collider their effects could be disentangled when both Z bosons decay leptonically. PMID:18851602

  17. A Landau-de Gennes theory for hard colloidal rods: Defects and tactoids

    NASA Astrophysics Data System (ADS)

    Everts, J. C.; Punter, M. T. J. J. M.; Samin, S.; van der Schoot, P.; van Roij, R.

    2016-05-01

    We construct a phenomenological Landau-de Gennes theory for hard colloidal rods by performing an order parameter expansion of the chemical-potential dependent grand potential. By fitting the coefficients to known results of Onsager theory, we are not only able to describe the isotropic-nematic phase transition as function of density, including the well-known density jump, but also the isotropic-nematic planar interface. The resulting theory is applied in calculations of the isotropic core size in a radial hedgehog defect, the density dependence of linear defects of hard rods in square confinement, and the formation of a nematic droplet in an isotropic background.

  18. Reconnection of vortex filaments in the complex Ginzburg-Landau equation

    NASA Astrophysics Data System (ADS)

    Gabbay, Michael; Ott, Edward; Guzdar, Parvez N.

    1998-08-01

    A criterion for the reconnection of vortex filaments in the complex Ginzburg-Landau equation is presented. In particular, we give an estimate of the maximum intervortex separation beyond which coplanar filaments of locally opposite charge will not reconnect. This is done by balancing the motion of the filaments toward each other that would result if they were straight (a two-dimensional effect) with the opposing motion due to the filament curvature. Numerical experiments are in good agreement with the estimated vortex separation.

  19. Resonant generation of an electron–positron pair by two photons to excited Landau levels

    SciTech Connect

    Diachenko, M. M. Novak, O. P.; Kholodov, R. I.

    2015-11-15

    We consider the resonant generation of an electron–positron pair by two polarized photons to arbitrarily low Landau levels. The resonance occurs when the energy of one photon exceeds the one-photon generation threshold, and the energy of the other photon is multiple to the spacing between the levels. The cross section of the process is determined taking into account the spins of particles. The order of magnitude of the cross section is the highest when the magnetic moments of the particles are oriented along the magnetic field.

  20. Resonance, particle trapping, and Landau damping in finite amplitude obliquely propagating waves

    NASA Technical Reports Server (NTRS)

    Palmadesso, P. J.

    1972-01-01

    The equations of motion for a particle in resonance with a small finite amplitude wave are solved approximately, using secularity free perturbation theory. The wave propagates at an arbitrary angle to a uniform background magnetic field in an infinite collisionless plasma. The wave fields include a longitudinal electrostatic component and elliptically polarized transverse electric and magnetic components. The trajectories of trapped and resonant untrapped particles are described, for each of the possible wave-particle resonances. These trajectories are used to construct an estimate of the nonlinear time dependent Landau damping rate of the wave.

  1. Magnetoinfrared Spectroscopy of Landau Levels and Zeeman Splitting of Three-Dimensional Massless Dirac Fermions in ZrTe(5).

    PubMed

    Chen, R Y; Chen, Z G; Song, X-Y; Schneeloch, J A; Gu, G D; Wang, F; Wang, N L

    2015-10-23

    We present a magnetoinfrared spectroscopy study on a newly identified three-dimensional (3D) Dirac semimetal ZrTe(5). We observe clear transitions between Landau levels and their further splitting under a magnetic field. Both the sequence of transitions and their field dependence follow quantitatively the relation expected for 3D massless Dirac fermions. The measurement also reveals an exceptionally low magnetic field needed to drive the compound into its quantum limit, demonstrating that ZrTe(5) is an extremely clean system and ideal platform for studying 3D Dirac fermions. The splitting of the Landau levels provides direct, bulk spectroscopic evidence that a relatively weak magnetic field can produce a sizable Zeeman effect on the 3D Dirac fermions, which lifts the spin degeneracy of Landau levels. Our analysis indicates that the compound evolves from a Dirac semimetal into a topological line-node semimetal under the current magnetic field configuration. PMID:26551130

  2. The Landau-de Gennes free energy expansion of a melt of V-shaped polymer molecules.

    PubMed

    Aliev, M A; Ugolkova, E A; Kuzminyh, N Yu

    2016-08-28

    The phase behavior of a monodisperse melt of polymer molecules consisting of two rod-like segments joined at an angle α has been inspected within the Landau theory of phase transitions. The interactions between monomer units were assumed to be of the Maier-Saupe form. The Landau-de Gennes expansion of the free energy of the melt has been obtained up to the sixth order in powers of the nematic order parameter, the coefficients of this expansion have been calculated from the microscopic model of polymer molecule. The phase diagram contains the regions of stability of isotropic, prolate uniaxial, oblate uniaxial, and biaxial nematic phases. The isotropic-uniaxial nematic and uniaxial-biaxial nematic transitions are of the first and second order, respectively. We found two Landau points in the phase diagram at which continuous transition from biaxial nematic state to isotropic phase occurs. PMID:27586947

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

    NASA Astrophysics Data System (ADS)

    Yan, Jie-Yun; Wang, Lan-Yu

    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.

  4. Landau level quantization for massless Dirac fermions in the spherical geometry: Graphene fractional quantum Hall effect on the Haldane sphere

    NASA Astrophysics Data System (ADS)

    Arciniaga, Michael; Peterson, Michael R.

    2016-07-01

    We derive the single-particle eigenenergies and eigenfunctions for massless Dirac fermions confined to the surface of a sphere in the presence of a magnetic monopole, i.e., we solve the Landau level problem for electrons in graphene on the Haldane sphere. With the single-particle eigenfunctions and eigenenergies we calculate the Haldane pseudopotentials for the Coulomb interaction in the second Landau level and calculate the effective pseudopotentials characterizing an effective Landau level mixing Hamiltonian entirely in the spherical geometry to be used in theoretical studies of the fractional quantum Hall effect in graphene. Our treatment is analogous to the formalism in the planar geometry and reduces to the planar results in the thermodynamic limit.

  5. Towards a generalized Landau-Zener formula for an interacting Bose-Einstein condensate in a two-level system

    SciTech Connect

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

    2006-06-15

    We consider the Landau-Zener problem for a Bose-Einstein condensate in a linearly varying two-level system, for the full many-particle system as well as in the mean-field approximation. Novel nonlinear eigenstates emerge in the mean-field description, which leads to a breakdown of adiabaticity: The Landau-Zener transition probability does not vanish even in the adiabatic limit. It is shown that the emergence of nonlinear eigenstates and thus the breakdown of adiabaticity corresponds to quasi-degenerate avoided crossings of the many-particle levels. The many-particle problem can be solved approximately within an independent crossings approximation, which yields an explicit generalized Landau-Zener formula. A comparison to numerical results for the many-particle system and the mean-field approximation shows an excellent agreement.

  6. Stable large-scale solver for Ginzburg-Landau equations for superconductors

    NASA Astrophysics Data System (ADS)

    Sadovskyy, I. A.; Koshelev, A. E.; Phillips, C. L.; Karpeyev, D. A.; Glatz, A.

    2015-08-01

    Understanding the interaction of vortices with inclusions in type-II superconductors is a major outstanding challenge both for fundamental science and energy applications. At application-relevant scales, the long-range interactions between a dense configuration of vortices and the dependence of their behavior on external parameters, such as temperature and an applied magnetic field, are all important to the net response of the superconductor. Capturing these features, in general, precludes analytical description of vortex dynamics and has also made numerical simulation prohibitively expensive. Here we report on a highly optimized iterative implicit solver for the time-dependent Ginzburg-Landau equations suitable for investigations of type-II superconductors on massively parallel architectures. Its main purpose is to study vortex dynamics in disordered or geometrically confined mesoscopic systems. In this work, we present the discretization and time integration scheme in detail for two types of boundary conditions. We describe the necessary conditions for a stable and physically accurate integration of the equations of motion. Using an inclusion pattern generator, we can simulate complex pinning landscapes and the effect of geometric confinement. We show that our algorithm, implemented on a GPU, can provide static and dynamic solutions of the Ginzburg-Landau equations for mesoscopically large systems over thousands of time steps in a matter of hours. Using our formulation, studying scientifically-relevant problems is a computationally reasonable task.

  7. Generic transition hierarchies of lattice HP protein adsorption: A Wang-Landau study

    NASA Astrophysics Data System (ADS)

    Li, Ying Wai; Landau, D. P.; Wüst, T.

    2012-02-01

    We have applied Wang-Landau sampling with appropriate trial movesootnotetextT. W"ust and D. P. Landau, Phy. Rev. Lett. 102, 178101 (2009). to investigate the thermodynamics and structural properties of the HP lattice protein modelootnotetextK. A. Dill, Biochemistry 24, 1501 (1985). interacting with an attractive substrate. The conformational ``phase transitions'' of several benchmark HP sequences have been identified by a comprehensive canonical analysis of the specific heat and structural observables, e. g. radius of gyration and thermal derivatives of number of surface contacts. Three major ``transitions'': adsorption, hydrophobic core formation, and ``flattening'' of adsorbed structures, are observed. Depending on the surface attractive strength relative to the intra-protein attraction among the H monomers, these processes take place in a different order upon cooling. We identify a small number of generic categories that are sufficient to classify the folding hierarchies for different HP chains consisting of assorted sequences and chain lengths, regardless of the monomer type that the surface attracts. We thus believe that this classification scheme is generally applicable to lattice protein adsorption problems.

  8. Combined action of phase-mixing and Landau damping causing strong decay of geodesic acoustic modes

    NASA Astrophysics Data System (ADS)

    Palermo, F.; Biancalani, A.; Angioni, C.; Zonca, F.; Bottino, A.

    2016-07-01

    We report evidence of a new mechanism able to damp very efficiently geodesic acoustic mode (GAM) in the presence of a nonuniform temperature profile in a toroidally confined plasma. This represents a particular case of a general mechanism that we have found and that can be observed whenever the phase-mixing acts in the presence of a damping effect that depends on the wave number k r . Here, in particular, the combined effect of the Landau and continuum damping is found to quickly redistribute the GAM energy in phase-space, due to the synergy of the finite orbit width of the passing ions and the cascade in wave number given by the phase-mixing. This damping mechanism is investigated analytically and numerically by means of global gyrokinetic simulations. When realistic parameter values of plasmas at the edge of a tokamak are used, damping rates up to 2 orders of magnitude higher than the Landau damping alone are obtained. We find in particular that, for temperature and density profiles characteristic of the high confinement mode, the so-called H-mode, the GAM decay time becomes comparable to or lower than the nonlinear drive time, consistently with experimental observations (Conway G. D. et al., Phys. Rev. Lett., 106 (2011) 065001).

  9. Dromion-like structures and stability analysis in the variable coefficients complex Ginzburg–Landau equation

    SciTech Connect

    Wong, Pring; Pang, Li-Hui; Huang, Long-Gang; Li, Yan-Qing; Lei, Ming; Liu, Wen-Jun

    2015-09-15

    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.

  10. Onset voltage shift due to nonzero Landau ground-state level in coherent magnetotransport

    NASA Astrophysics Data System (ADS)

    Kim, Dae Kwan; Roblin, Patrick

    2002-03-01

    Coherent electron transport in double-barrier heterostructures with parallel electric and magnetic fields is analyzed theoretically and with the aid of a quantum simulator accounting for three-dimensional transport effects. The onset-voltage shift induced by the magnetic field in resonant tunneling diodes, which was previously attributed to the cyclotron frequency wc inside the well is found to arise from an upward shift of the nonzero ground (lowest) Landau state energy in the entire quantum region where coherent transport takes place. The spatial dependence of the cyclotron frequency is accounted for and verified to have a negligible impact on resonant tunneling for the device and magnetic field strength considered. A correction term for the onset-voltage shift arising from the magnetic field dependence of the chemical potential is also derived. The Landau ground state with its nonvanishing finite harmonic oscillator energy ħwc/2 is verified, however, to be the principal contributor to the onset voltage shift at low temperatures.

  11. High Pressure Studies of the Second Landau Level Region of a Two-Dimensional Electron System

    NASA Astrophysics Data System (ADS)

    Schreiber, Katherine; Samkharadze, Nodar; Gardner, Geoffrey; Fradkin, Eduardo; Manfra, Michael; Csathy, Gabor

    Hydrostatic pressure has become a prevalent tool in condensed matter systems because the application of pressure to crystalline structures results in the shrinking of the lattice constant. This allows one to tune the Bloch wavefunction of the electrons and therefore all band parameters such as effective carrier mass, carrier density, and effective g-factor. In this manner, pressure acts as a probe into various strongly interacting electronic states. Motivated in particular by the capability to discern the spin polarization of quantum Hall states, we apply hydrostatic pressure up to 10 kbar to a two dimensional electron system (2DES) in a high-mobility GaAs/AlGaAs quantum well. This 2DES is subjected to milliKelvin temperatures and strong magnetic fields to observe the effect of pressure on fractional quantum Hall states, especially those in higher Landau levels, a regime not previously studied under pressure. We report our findings, focusing on the observation of a pressure-driven transition from a fractional quantum Hall state to the quantum Hall nematic phase in the second Landau level. Grants: Researchers at Purdue and N. Samkharadze: US DOE, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, DE-SC0006671. E. Fradkin: US NSF, DMR 1408713.

  12. Hysteresis phenomena in shape memory alloys by non-isothermal Ginzburg-Landau models

    NASA Astrophysics Data System (ADS)

    Dhote, R. P.; Fabrizio, M.; Melnik, R. N. V.; Zu, J.

    2013-09-01

    In this paper, we propose the new one- and three- dimensional models for the description of hysteretic phenomena in shape memory alloys (SMAs). These thermodynamic models are non-isothermal and allow to account for the thermo-mechanical material properties of both austenite and martensite phases based on the local phase value of the order parameter. They are based on the Ginzburg-Landau free energy and the phase field theory. The core of the models is a phase evolution governed by the time dependent Ginzburg-Landau (TDGL) equation and the conservation balance laws with nonlinear coupling between stress, strain and the phase order parameter. The models account for the gradient energy and have been tested in the study of material properties evolution under harmonic stress loading for all important practical cases. The representative numerical simulations have been carried out here without the gradient energy term. The developed models account for the phase dependent properties based on the compliance tensor as a function of the order parameter and stress. We also compared the results obtained with these models and observed differences in homogeneous and inhomogeneous situations due to the change in compliance. In this way, the description of quasiplastic and pseudoelastic behaviors in SMA specimens is improved and becomes in an agreement with existing experiments.

  13. Landau levels as a limiting case of a model with the morse-like magnetic field

    NASA Astrophysics Data System (ADS)

    Fakhri, H.; Mojaveri, B.; Nobary, M. A. Gomshi

    2010-12-01

    We consider the quantum mechanics of an electron trapped on an infinite band along the x-axis in the presence of the Morse-like perpendicular magnetic field B=-Bek with B0 > 0 as a constant strength and a0 as the width of the band. It is shown that the square integrable pure states realize representations of su(1, 1) algebra via the quantum number corresponding to the linear momentum in the y-direction. The energy of the states increases by decreasing the width a0 while it is not changed by B0. It is quadratic in terms of two quantum numbers, and the linear spectrum of the Landau levels is obtained as a limiting case of a0 → ∞. All of the lowest states of the su(1, 1) representations minimize uncertainty relation and the minimizing of their second and third states is transformed to that of the Landau levels in the limit a0 → ∞. The compact forms of the Barut-Girardello coherent states corresponding to l-representation of su(1, 1) algebra and their positive definite measures on the complex plane are also calculated.

  14. Dynamics of perturbed wavetrain solutions to the Ginzburg-Landau equation

    SciTech Connect

    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.

  15. The Landau pole and Z‧ decays in the 331 dilepton model

    NASA Astrophysics Data System (ADS)

    Martínez, R.; Ochoa, F.

    2007-08-01

    We calculate the decay widths and branching ratios of the extra neutral boson Z’ predicted by the 331 dilepton model in the framework of two different particle contents. These calculations are performed taking into account oblique radiative corrections and flavor changing neutral currents (FCNC) under the ansatz of Matsuda as a texture for the quark mass matrices. Contributions of the order of 10-1-10-2 are obtained in the branching ratios, and the partial widths about one order of magnitude bigger in relation with other 331 models are also obtained. A Landau-like pole arises at 3.5 TeV considering the full particle content of the minimal dilepton model (MDM), where the exotic sector is considered as a degenerate spectrum at the 3 TeV scale. The Landau pole problem can be avoided at the TeV scales if a new leptonic content running below the threshold at 3 TeV is implemented as suggested by other authors.

  16. Observation of coherent oscillation in single-passage Landau-Zener transitions

    PubMed Central

    Sun, Guozhu; Wen, Xueda; Gong, Ming; Zhang, Dan-Wei; Yu, Yang; Zhu, Shi-Liang; Chen, Jian; Wu, Peiheng; Han, Siyuan

    2015-01-01

    Landau-Zener transition (LZT) has been explored in a variety of physical systems for coherent population transfer between different quantum states. In recent years, there have been various proposals for applying LZT to quantum information processing because when compared to the methods using ac pulse for coherent population transfer, protocols based on LZT are less sensitive to timing errors. However, the effect of finite range of qubit energy available to LZT based state control operations has not been thoroughly examined. In this work, we show that using the well-known Landau-Zener formula in the vicinity of an avoided energy-level crossing will cause considerable errors due to coherent oscillation of the transition probability in a single-passage LZT experiment. The data agree well with the numerical simulations which take the transient dynamics of LZT into account. These results not only provide a closer view on the issue of finite-time LZT but also shed light on its effects on the quantum state manipulation. PMID:25684697

  17. Perturbative approach to the structure of a planar interface in the Landau-de Gennes model.

    PubMed

    Pełka, Robert; Saito, Kazuya

    2006-10-01

    The structure of nearly static planar interfaces is studied within the framework of the Landau-de Gennes model with the dynamics governed by the time-dependent Ginzburg-Landau equation. To account for the full elastic anisotropy the free energy expansion is extended to include a third order gradient term. The solutions corresponding to the in-plane or homeotropic director alignment at the interface are sought. For this purpose a consistent perturbative scheme is constructed which enables one to calculate successive corrections to the velocity and the order parameter of the interface. The implications of the solutions are discussed. The elastic anisotropy introduces asymmetry into the order parameter and free energy profiles, even for the high symmetry homeotropic configuration. The velocity of the interface with the homeotropic or in-plane alignment is enhanced or reduced, respectively. There is no reorientation of the optical axis in the boundary layer. For the class of nematogens with approximate splay-bend degeneracy the temperature dependence of the interface velocity is weakly affected by the remaining twist anisotropy. PMID:17155076

  18. On the time-dependent resonant width for Landau damping: theory and PIC simulation

    NASA Astrophysics Data System (ADS)

    Grismayer, T.; Fahlen, J. E.; Decyk, V. K.; Mori, W. B.

    2011-07-01

    We use electrostatic partice-in-cell (PIC) simulations and theory to study the damping of 1D plasma waves. We consider the linear regime where the asymptotic damping rate is much bigger than the bounce frequency. In this regime the waves are typically very small and often below the thermal noise in simulations and experiments. These waves can be studied using a subtraction technique in which two simulations with identical random number generation seeds are carried out. In the first, a small amplitude wave is excited. In the second simulation no wave is excited. The results from each simulation are subtracted providing a clean linear wave that can be studied. Since the Landau derivation does not provide a description of damping in terms of individual particle trajectories, we analyze Landau damping using a Lagrangian approach based on energy conservation and the linearized particle trajectories. This method provides a time-dependent resonance curve and the energy transfer of the particles in the damping process. The time-dependent resonant width measured in the simulations is compared with the theoretical prediction. Simulations in which particles within the resonance width are removed are also presented.

  19. The Ginzburg-Landau theory for a thin superconducting loop in a large magnetic field

    NASA Astrophysics Data System (ADS)

    Shieh, Tien-Tsan

    When a temperature is lower than a certain critical value, a superconducting sample undergoes a phase transition from a normal state to a superconducting state. This onset process of superconductivity can be studied as a Rayleigh quotient under the framework of the Ginzburg-Landau theory. In particular, I study the onset problem for a thin superconducting loop in a large magnetic field. This double limit problem was first carried out by Richardson and Rubinstein by using formal asymptotic expansions. I rigorously show that a one-dimensional Rayleigh quotient in the spirit of Gamma-convergence. The full Gamma-convergence of the Ginzburg-Landau functional for a thin domain and a large field is also obtained. The rigorous analysis in this thesis shows the validity of Richardson and Rubinstein's formal results. It is also shown that the Rayleigh quotient related to this onset problem has a periodic variation with a parabolic background. The parabolic background effect can be explained by a non-ignorable effect if finite-width cross-section of a thin superconducting sample. This illustrate the observation of the Little-Parks experiment.

  20. Superlattice Patterns in the Complex Ginzburg--Landau Equation with Multiresonant Forcing

    NASA Astrophysics Data System (ADS)

    Conway, Jessica M.; Riecke, Hermann

    2009-01-01

    Motivated by the rich variety of complex patterns observed on the surface of fluid layers that are vibrated at multiple frequencies, we investigate the effect of such resonant forcing on systems undergoing a Hopf bifurcation to spatially homogeneous oscillations. We use an extension of the complex Ginzburg-Landau equation that systematically captures weak forcing functions with a spectrum consisting of frequencies close to the 1:1-, the 1:2-, and the 1:3-resonance. By slowly modulating the amplitude of the 1:2-forcing component, we render the bifurcation to subharmonic patterns supercritical despite the quadratic interaction introduced by the 1:3-forcing. Our weakly nonlinear analysis shows that quite generally the forcing function can be tuned such that resonant triad interactions with weakly damped modes stabilize subharmonic superlattice patterns comprising four or five Fourier modes. Using direct simulations of the extended complex Ginzburg-Landau equation, we confirm our weakly nonlinear analysis. In sufficiently large systems domains of different complex patterns compete with each other on a slow time scale. As expected from leading-order energy arguments, with increasing strength of the triad interaction the more complex patterns eventually win out against the simpler patterns. We characterize these ordering dynamics using the spectral entropy of the patterns. For system parameters reported for experiments on the oscillatory Belousov-Zhabotinsky reaction we explicitly show that the forcing parameters can be tuned such that 4-mode patterns are the preferred patterns.

  1. Efficient combination of Wang-Landau and transition matrix Monte Carlo methods for protein simulations.

    PubMed

    Ghulghazaryan, Ruben G; Hayryan, Shura; Hu, Chin-Kun

    2007-02-01

    An efficient combination of the Wang-Landau and transition matrix Monte Carlo methods for protein and peptide simulations is described. At the initial stage of simulation the algorithm behaves like the Wang-Landau algorithm, allowing to sample the entire interval of energies, and at the later stages, it behaves like transition matrix Monte Carlo method and has significantly lower statistical errors. This combination allows to achieve fast convergence to the correct values of density of states. We propose that the violation of TTT identities may serve as a qualitative criterion to check the convergence of density of states. The simulation process can be parallelized by cutting the entire interval of simulation into subintervals. The violation of ergodicity in this case is discussed. We test the algorithm on a set of peptides of different lengths and observe good statistical convergent properties for the density of states. We believe that the method is of general nature and can be used for simulations of other systems with either discrete or continuous energy spectrum. PMID:17195159

  2. Emergent particle-hole symmetry in the half-filled Landau level

    NASA Astrophysics Data System (ADS)

    Mulligan, Michael; Raghu, S.; Fisher, Matthew P. A.

    2016-08-01

    We provide an effective description of a particle-hole symmetric state of electrons in a half-filled Landau level, starting from the traditional approach pioneered by Halperin, Lee, and Read [Phys. Rev. B 47, 7312 (1993), 10.1103/PhysRevB.47.7312]. Specifically, we study a system consisting of alternating quasi-one-dimensional strips of composite Fermi liquid (CFL) and composite hole liquid (CHL), both of which break particle-hole symmetry. When the CFL and CHL strips are identical in size, the resulting state is manifestly invariant under the combined action of a particle-hole transformation with respect to a single Landau level (which interchanges the CFL and CHL) and translation by one unit, equal to the strip width, in the direction transverse to the strips. At distances long compared to the strip width, we demonstrate that the system is described by a Dirac fermion coupled to an emergent gauge field, with an antiunitary particle-hole symmetry, as recently proposed by Son [Phys. Rev. X 5, 031027 (2015), 10.1103/PhysRevX.5.031027].

  3. Magnetic Photon Splitting: The S-Matrix Formulation in the Landau Representation

    NASA Technical Reports Server (NTRS)

    Baring, Matthew G.

    1999-01-01

    Calculations of reaction rates for the third-order QED process of photon splitting gamma yields gamma.gamma in strong magnetic fields traditionally have employed either the effective Lagrangian method or variants of Schwinger's proper-time technique. Recently, Mentzel, Berg and Wunner [1] presented an alternative derivation via an S-matrix formulation in the Landau representation. Advantages of such a formulation include the ability to compute rates near pair resonances above pair threshold. This paper presents new developments of the Landau representation formalism as applied to photon splitting, providing significant, advances beyond the work of [1] by summing over the spin quantum numbers of the electron propagators, and analytically integrating over the component of momentum of the intermediate states that is parallel to field. The ensuing tractable expressions for the scattering amplitudes are satisfyingly compact, and of an appearance familiar to S-matrix theory applications. Such developments can facilitate numerical computations of splitting considerably both below and above pair threshold. Specializations to two regimes of interest are obtained, namely the limit of highly supercritical fields and the domain where photon energies are far inferior to that for the threshold of single-photon pair creation. In particular, for the first time the low-frequency amplitudes are simply expressed in terms of the Gamma function, its integral and its derivatives. In addition, the equivalence of the asymptotic forms in these two domains to extant results from effective Lagrangian/proper- time formulations is demonstrated.

  4. Infrared analysis of Dyson-Schwinger equations taking into account the Gribov horizon in Landau gauge

    SciTech Connect

    Huber, M. Q.; Alkofer, R.; Sorella, S. P.

    2010-03-15

    The low momentum behavior of the Landau gauge Gribov-Zwanziger action is investigated using the respective Dyson-Schwinger equations. Because of the mixing of the gluon and the auxiliary fields four scenarios can be distinguished for the infrared behavior. Two of them lead to inconsistencies and can be discarded. Another one corresponds to the case where the auxiliary fields behave exactly like the Faddeev-Popov ghosts and the same scaling relation as in standard Landau gauge, {kappa}{sub A}+2{kappa}{sub c}=0, is valid. Even the parameter {kappa} is found to be the same, 0.595. The mixed propagators, which appear, are suppressed in all loops, and their anomalous infrared exponent can also be determined. A fourth case provides an even stricter scaling relation that includes also the mixed propagators, but possesses the same qualitative feature, i.e. the propagators of the Faddeev-Popov ghost and the auxiliary fields are infrared enhanced and the mixed and the gluon propagators are infrared suppressed. In this case the system of equations to obtain the parameter {kappa} is nonlinear in all variables.

  5. Observation of coherent oscillation in single-passage Landau-Zener transitions.

    PubMed

    Sun, Guozhu; Wen, Xueda; Gong, Ming; Zhang, Dan-Wei; Yu, Yang; Zhu, Shi-Liang; Chen, Jian; Wu, Peiheng; Han, Siyuan

    2015-01-01

    Landau-Zener transition (LZT) has been explored in a variety of physical systems for coherent population transfer between different quantum states. In recent years, there have been various proposals for applying LZT to quantum information processing because when compared to the methods using ac pulse for coherent population transfer, protocols based on LZT are less sensitive to timing errors. However, the effect of finite range of qubit energy available to LZT based state control operations has not been thoroughly examined. In this work, we show that using the well-known Landau-Zener formula in the vicinity of an avoided energy-level crossing will cause considerable errors due to coherent oscillation of the transition probability in a single-passage LZT experiment. The data agree well with the numerical simulations which take the transient dynamics of LZT into account. These results not only provide a closer view on the issue of finite-time LZT but also shed light on its effects on the quantum state manipulation. PMID:25684697

  6. Efficient solution of 3D Ginzburg-Landau problem for mesoscopic superconductors

    NASA Astrophysics Data System (ADS)

    Pereira, Paulo J.; Moshchalkov, Victor V.; Chibotaru, Liviu F.

    2014-03-01

    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.

  7. Vacuum birefringence in strong magnetic fields: (II) Complex refractive index from the lowest Landau level

    SciTech Connect

    Hattori, Koichi; Itakura, Kazunori

    2013-07-15

    We compute the refractive indices of a photon propagating in strong magnetic fields on the basis of the analytic representation of the vacuum polarization tensor obtained in our previous paper. When the external magnetic field is strong enough for the fermion one-loop diagram of the polarization tensor to be approximated by the lowest Landau level, the propagating mode in parallel to the magnetic field is subject to modification: The refractive index deviates from unity and can be very large, and when the photon energy is large enough, the refractive index acquires an imaginary part indicating decay of a photon into a fermion–antifermion pair. We study dependences of the refractive index on the propagating angle and the magnetic-field strength. It is also emphasized that a self-consistent treatment of the equation which defines the refractive index is indispensable for accurate description of the refractive index. This self-consistent treatment physically corresponds to consistently including the effects of back reactions of the distorted Dirac sea in response to the incident photon. -- Highlights: •Vacuum birefringence and photon decay are described by the complex refractive index. •Resummed photon vacuum polarization tensor in the lowest Landau level is used. •Back reactions from the distorted Dirac sea are self-consistently taken into account. •Self-consistent treatment drastically changes structure in photon energy dependence. •Dependences on photon propagation angle and magnetic-field strength are presented.

  8. Derivation of a time dependent Schrödinger equation as the quantum mechanical Landau-Lifshitz-Bloch equation.

    PubMed

    Wieser, R

    2016-10-01

    The derivation of the time dependent Schrödinger equation with transversal and longitudinal relaxation, as the quantum mechanical analog of the classical Landau-Lifshitz-Bloch equation, has been described. Starting from the classical Landau-Lifshitz-Bloch equation the transition to quantum mechanics has been performed and the corresponding von-Neumann equation deduced. In a second step the time Schrödinger equation has been derived. Analytical proofs and computer simulations show the correctness and applicability of the derived Schrödinger equation. PMID:27494599

  9. Chiral symmetry and fermion doubling in the zero-mode Landau levels of massless Dirac fermions with disorder

    SciTech Connect

    Kawarabayashi, Tohru; Honda, Takahiro; Aoki, Hideo; Hatsugai, Yasuhiro

    2013-12-04

    The effect of disorder on the Landau levels of massless Dirac fermions is examined for the cases with and without the fermion doubling. To tune the doubling a tight-binding model having a complex transfer integral is adopted to shift the energies of two Dirac cones, which is theoretically proposed earlier and realizable in cold atoms in an optical lattice. In the absence of the fermion doubling, the n = 0 Landau level is shown to exhibit an anomalous sharpness even if the disorder is uncorrelated in space (i.e., large K-K' scattering). This anomaly occurs when the disorder respects the chiral symmetry of the Dirac cone.

  10. Simulations of the fusion of necklace-ring pattern in the complex Ginzburg-Landau equation by lattice Boltzmann method

    NASA Astrophysics Data System (ADS)

    Zhang, Jianying; Yan, Guangwu

    2016-04-01

    A lattice Boltzmann model for solving the (2+1) dimensional cubic-quintic complex Ginzburg-Landau equation (CQCGLE) is proposed. Different from the classic lattice Boltzmann models, this lattice Boltzmann model is based on uniformly distributed lattice points in a two-dimensional space, and the evolution of the model is about a spatial axis rather than time. The algorithm provides advantages similar to the lattice Boltzmann method in that it is easily adapted to complex Ginzburg-Landau equations. Numerical results reproduce the phenomena of the fusion of necklace-ring pattern and the effect of non-linearity on the soliton in the CQCGLE.

  11. Spatiotemporal lattice Boltzmann model for the three-dimensional cubic-quintic complex Ginzburg-Landau equation

    NASA Astrophysics Data System (ADS)

    Zhang, Jianying; Yan, Guangwu

    2015-12-01

    A spatiotemporal lattice Boltzmann model for solving the three-dimensional cubic-quintic complex Ginzburg-Landau equation (CQCGLE) is proposed. Different from the classic lattice Boltzmann models, this lattice Boltzmann model is based on uniformly distributed lattice points in a three-dimensional spatiotemporal space, and the evolution of the model is about a spatial axis rather than time. The algorithm possesses advantages similar to the lattice Boltzmann method in that it is easily adapted to complex Ginzburg-Landau equations. Examples show that the model reproduces the phenomena in the CQCGLE accurately.

  12. Landau parameters for isospin asymmetric nuclear matter based on a relativistic model of composite and finite extension nucleons

    SciTech Connect

    Aguirre, R. M.; Paoli, A. L. de

    2007-04-15

    We study the properties of cold asymmetric nuclear matter at high density, applying the quark meson coupling model with excluded volume corrections in the framework of the Landau theory of relativistic Fermi liquids. We discuss the role of the finite spatial extension of composite baryons on dynamical and statistical properties such as the Landau parameters, the compressibility, and the symmetry energy. We have also calculated the low-lying collective eigenfrequencies arising from the collisionless quasiparticle transport equation, considering both unstable and stable modes. An overall analysis of the excluded volume correlations on the collective properties is performed.

  13. Performance of Replica-Exchange Wang-Landau Sampling for the 2D Ising Model: A Brief Survey

    SciTech Connect

    Zhao, Yiwei; Cheung, Siu Wun; Li, Ying Wai; Eisenbach, Markus

    2014-01-01

    We report a brief performance study of the replica-exchange Wang-Landau algorithm, a recently proposed parallel realization of Wang-Landau sampling, using the 2D Ising model as a test case. The simulation time is found to scale inversely with the square root of the number of subwindows (and thus number of processors) used to span the global parameter space. We also investigate the time profiles for random walkers in dierent subwindows to complete iterations, which will aid the development of and adaptive load-balancing scheme.

  14. Observation of time-domain Rabi oscillations in the Landau-Zener regime with a single electronic spin.

    PubMed

    Zhou, Jingwei; Huang, Pu; Zhang, Qi; Wang, Zixiang; Tan, Tian; Xu, Xiangkun; Shi, Fazhan; Rong, Xing; Ashhab, S; Du, Jiangfeng

    2014-01-10

    It is theoretically known that the quantum interference of a long sequence of Landau-Zener transitions can result in Rabi oscillations. Because of its stringent requirements, however, this phenomenon has never been experimentally observed in the time domain. Using a nitrogen-vacancy (NV) center spin in isotopically purified diamond, we observed the Rabi oscillations resulting from more than 100 Landau-Zener processes. Our results demonstrate favorable quantum controllability of NV centers, which could find applications in quantum metrology and quantum information processing. PMID:24483877

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

    SciTech Connect

    Damski, Bogdan

    2005-07-15

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

    SciTech Connect

    Cooper, F.

    1996-12-31

    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 {sigma} model, we demonstrate that many of Landau`s ideas are verified in explicit field theory calculations.

  17. Werner Heisenberg zum 100. Geburtstag: Pionier der Quantenmechanik

    NASA Astrophysics Data System (ADS)

    Jacobi, Manfred

    2001-11-01

    Werner Heisenberg war eine der prägendsten Gestalten der Physik des 20. Jahrhunderts. Zu seinen wichtigsten Verdiensten gehören die Grundlegung der Quantenmechanik, die Formulierung der Unschärferelationen sowie die Beteiligung an der Ausarbeitung der Kopenhagener Deutung der Quantenmechanik. Darüber hinaus lieferte er Arbeiten von fundamentalem Charakter zur Theorie des Atomkerns, zur kosmischen Strahlung und zur Quantenfeldtheorie. Während des Krieges war er an den Arbeiten des Uranvereins beteiligt, der die Möglichkeit einer Entwicklung von Kernwaffen untersuchte, jedoch über Vorarbeiten zur Reaktorphysik nicht hinauskam. Wegen dieser Tätigkeit wurde er bei Kriegsende für einige Monate in England interniert. Nach seiner Rückkehr widmete er sich vor allem dem Aufbau der Physik in Deutschland, die während der NS-Zeit nahezu ihrer gesamten Substanz beraubt worden war.

  18. Landau Energy Loss in Liquid Scintillator and the Search for Wifs with the LVD Experiment.

    NASA Astrophysics Data System (ADS)

    Tang, Jie

    The LVD experiment at Gran Sasso, Italy, is described, and data since the completion of the first tower (one fifth of the whole LVD) are analyzed. The dE/dx distribution of reconstructed high-energy muons in the scintillator counters is obtained. This distribution is compared with predictions by a GEANT3 Monte Carlo simulation of cosmic muons going through the LVD detector. Its shape is similar to the Landau approximation. In the data from a total running time of 245 days, 159286 clearly separable charged tracks going through the detector were reconstructed. No WIF (Weakly-Interacting Fractionally-charged particle) is observed. Since the early 1930's to the 1980's, theories on the dE/dx distribution of charged particles in matter have evolved from the fundamental work done by Bethe, Bloch, Landau, Symon, Vavilov and others with the inclusion of more precise corrections of the density effect and the shell effect. At the LVD experiment, through a procedure of gain-factor calibration at every period of 20 days, to compensate for instability and nonuniformity of the scintillator counters and their readout, the muon dE/dx distribution is measured; it conforms to the Landau approximation. The precision of the dE/dx measurement is 7.6% (one sigma).. WIF particles are speculated by modern theories. Because dE/dx is proportional to the square of the charge carried by the incident particle, any WIF going through the LVD liquid scintillator will reveal itself by its dE/dx being on the low side of the carefully calibrated muon dE/dx distribution. Calculation has shown that when the charge of a WIF is as low as {2over 3} e, it still generates enough ionization in the LVD limited streamer tubes and thus its track is as visible as a muon track in the detector. Such events are not found. Assuming a uniform flux distribution of WIF particles coming from the atmosphere, the upper limit of their flux at the LVD site is 4.4 times rm 10^{-14} cm^{-2}sterad ^{-1}sec^{-1}. (Copies

  19. Hydrodynamic Instability in an Extended Landau/Levich Model of Liquid-Propellant Combustion

    NASA Technical Reports Server (NTRS)

    Margolis, Stephen B.; Sackesteder, Kurt (Technical Monitor)

    1998-01-01

    The classical Landau/Levich models of liquid propellant combustion, which serve as seminal examples of hydrodynamic instability in reactive systems, have been combined and extended to account for a dynamic dependence, absent in the original formulations, of the local burning rate on the local pressure and/or temperature fields. The resulting model admits an extremely rich variety of both hydrodynamic and reactive/diffusive instabilities that can be analyzed in various limiting parameter regimes. In the present work, a formal asymptotic analysis, based on the realistic smallness of the gas-to-liquid density ratio, is developed to investigate the combined effects of gravity, surface tension and viscosity on the hydrodynamic instability of the propagating liquid/gas interface. In particular, a composite asymptotic expression, spanning three distinguished wavenumber regimes, is derived for both cellular and pulsating hydrodynamic neutral stability boundaries A(sub p)(k), where A(sub p) is the pressure sensitivity of the burning rate and k is the disturbance wavenumber. For the case of cellular (Landau) instability, the results demonstrate explicitly the stabilizing effect of gravity on long-wave disturbances, the stabilizing effect of viscosity and surface tension on short-wave perturbations, and the instability associated with intermediate wavenumbers for critical negative values of A(sub p). In the limiting case of weak gravity, it is shown that cellular hydrodynamic instability in this context is a long-wave instability phenomenon, whereas at normal gravity, this instability is first manifested through O(l) wavenumber disturbances. It is also demonstrated that, in the large wavenumber regime, surface tension and both liquid and gas viscosity all produce comparable stabilizing effects in the large-wavenumber regime, thereby providing significant modifications to previous analyses of Landau instability in which one or more of these effects were neglected. In contrast

  20. ARPES studies of van der Waals heterostructure

    NASA Astrophysics Data System (ADS)

    Wang, Eryin; Lu, Xiaobo; Chen, Guorui; Fedorov, Alexei V.; Zhang, Yuanbo; Zhang, Guangyu; Zhou, Shuyun

    Van der Waals heterostructures are a novel class of ``materials by design'' which are formed by stacking different two-dimensional crystals together via van der Waals interaction. The periodic potential by the Moir é superlattice can be used as a control knob for tuning the electronic properties of two dimensional materials and can induce various novel quantum phenomena. Here we report direct electronic structure studies the of a model van der Waals heterostructure using angle-resolved photoemission spectroscopy (ARPES). This work is supported by the National Natural Science Foundation of China and Ministry of Education of China.

  1. Qualitätsmanagement in der Lebensmittelindustrie

    NASA Astrophysics Data System (ADS)

    Thorn, Volker

    Die wesentlichen Kunden der Lebensmittelindustrie sind der Einzel- und Großhandel und die Verbraucher. Jedes Unternehmen kann mittel- und langfristig nur existieren, wenn seine Kunden zufrieden sind. Kunden sind zufrieden, wenn ihre Erwartungen, die sie an Produkt, Service und Preis stellen, erfüllt werden. Also die bestimmte erwartete Qualität (Leistung) sichergestellt wird. Trotz aller Bemühungen und Anstrengungen der Anbieter, Qualitätsprodukte auf den Markt zu bringen, kames in den letzten Jahren immer wieder zu Lebensmittelskandalen.

  2. Anomalous Energy Gaps of the Odd Denominator Fractional Quantum Hall States in Different Spin Branches of the Second Landau Level

    NASA Astrophysics Data System (ADS)

    Kleinbaum, Ethan; Kumar, Ashwani; Manfra, Michael; Pfeiffer, Loren; West, Ken; Csathy, Gabor

    2013-03-01

    The nature of the fractional quantum Hall states forming in the second Landau level, including those with odd denominator Landau level filling factors, remain unknown. Conjectures of nonconventional origins have lead to the investigation of several odd denominator states in the lower spin branch of the second Landau level, such as the ones at ν=2+1/3 and 2+2/3. We report first measurements of the energy gaps in the upper spin branch of the second Landau level at ν=3+1/3, 3+2/3, 3+1/5 and 3+4/5. A comparison of the energy gaps of these states to those of their counterparts in the lower spin branch reveals a surprising reversal in the relative magnitudes of the states at partial filling factors 1/3 and 1/5. We explore possible explanations of this unusual observation. The work at Purdue was supported by the DOE BES contract no. DE-SC0006671. K.K. West and L.N. Pfeiffer acknowledge the support of the Princeton NSF-MRSEC and the Moore Foundation.

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

    PubMed

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

    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. PMID:27475398

  4. Numerical solution of the time dependent Ginzburg-Landau equations for mixed (d + s)-wave superconductors

    SciTech Connect

    Gonçalves, W. C.; Sardella, E.; Becerra, V. F.; Milošević, M. V.; Peeters, F. M.

    2014-04-15

    The time-dependent Ginzburg-Landau formalism for (d + s)-wave superconductors and their representation using auxiliary fields is investigated. By using the link variable method, we then develop suitable discretization of these equations. Numerical simulations are carried out for a mesoscopic superconductor in a homogeneous perpendicular magnetic field which revealed peculiar vortex states.

  5. Inferring generalized time-dependent complex Ginzburg-Landau equations from modulus and gauge-field information

    SciTech Connect

    Yu, Rotha P.; Paganin, David M.; Morgan, Michael J.

    2008-04-01

    We develop a means to 'measure' the generalized 2+1-dimensional time-dependent complex Ginzburg-Landau equation, given both the wave-function modulus and gauge-field information over a series of five planes that are closely spaced in time. The methodology is tested using simulated data for a thin-film high-temperature superconductor in the Meissner state.

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    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.

  7. Observation of Landau levels on nitrogen-doped flat graphite surfaces without external magnetic fields

    NASA Astrophysics Data System (ADS)

    Kondo, Takahiro; Guo, Donghui; Shikano, Taishi; Suzuki, Tetsuya; Sakurai, Masataka; Okada, Susumu; Nakamura, Junji

    2015-11-01

    Under perpendicular external magnetic fields, two-dimensional carriers exhibit Landau levels (LLs). However, it has recently been reported that LLs have been observed on graphene and graphite surfaces without external magnetic fields being applied. These anomalous LLs have been ascribed primarily to a strain of graphene sheets, leading to in-plane hopping modulation of electrons. Here, we report the observation of the LLs of massive Dirac fermions on atomically flat areas of a nitrogen-doped graphite surface in the absence of external magnetic fields. The corresponding magnetic fields were estimated to be as much as approximately 100 T. The generation of the LLs at the area with negligible strain can be explained by inequivalent hopping of π electrons that takes place at the perimeter of high-potential domains surrounded by positively charged substituted graphitic-nitrogen atoms.

  8. Boundary Behavior of the Ginzburg-Landau Order Parameter in the Surface Superconductivity Regime

    NASA Astrophysics Data System (ADS)

    Correggi, Michele; Rougerie, Nicolas

    2016-01-01

    We study the 2D Ginzburg--Landau theory for a type-II superconductor in an applied magnetic field varying between the second and third critical value. In this regime the order parameter minimizing the GL energy is concentrated along the boundary of the sample and is well approximated to leading order (in L 2 norm) by a simplified 1D profile in the direction perpendicular to the boundary. Motivated by a conjecture of Xing-Bin Pan, we address the question of whether this approximation can hold uniformly in the boundary region. We prove that this is indeed the case as a corollary of a refined, second order energy expansion including contributions due to the curvature of the sample. Local variations of the GL order parameter are controlled by the second order term of this energy expansion, which allows us to prove the desired uniformity of the surface superconductivity layer.

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

    NASA Astrophysics Data System (ADS)

    Grigorishin, Konstantin V.

    2016-04-01

    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.

  10. Novel asymmetric representation method for solving the higher-order Ginzburg-Landau equation

    NASA Astrophysics Data System (ADS)

    Wong, Pring; Pang, Lihui; Wu, Ye; Lei, Ming; Liu, Wenjun

    2016-04-01

    In ultrafast optics, optical pulses are generated to be of shorter pulse duration, which has enormous significance to industrial applications and scientific research. The ultrashort pulse evolution in fiber lasers can be described by the higher-order Ginzburg-Landau (GL) equation. However, analytic soliton solutions for this equation have not been obtained by use of existing methods. In this paper, a novel method is proposed to deal with this equation. The analytic soliton solution is obtained for the first time, and is proved to be stable against amplitude perturbations. Through the split-step Fourier method, the bright soliton solution is studied numerically. The analytic results here may extend the integrable methods, and could be used to study soliton dynamics for some equations in other disciplines. It may also provide the other way to obtain two-soliton solutions for higher-order GL equations.

  11. The fascinating world of the Landau-Lifshitz-Gilbert equation: an overview.

    PubMed

    Lakshmanan, M

    2011-03-28

    The Landau-Lifshitz-Gilbert (LLG) equation is a fascinating nonlinear evolution equation both from mathematical and physical points of view. It is related to the dynamics of several important physical systems such as ferromagnets, vortex filaments, moving space curves, etc. and has intimate connections with many of the well-known integrable soliton equations, including nonlinear Schrödinger and sine-Gordon equations. It can admit very many dynamical structures including spin waves, elliptic function waves, solitons, dromions, vortices, spatio-temporal patterns, chaos, etc. depending on the physical and spin dimensions and the nature of interactions. An exciting recent development is that the spin torque effect in nanoferromagnets is described by a generalization of the LLG equation that forms a basic dynamical equation in the field of spintronics. This article will briefly review these developments as a tribute to Robin Bullough who was a great admirer of the LLG equation. PMID:21320917

  12. Landau damping effects in the synchronization of conformist and contrarian oscillators

    PubMed Central

    Qiu, Tian; Zhang, Yue; Liu, Jie; Bi, Hongjie; Boccaletti, S.; Liu, Zonghua; Guan, Shuguang

    2015-01-01

    Two decades ago, a phenomenon resembling Landau damping was described in the synchronization of globally coupled oscillators: the evidence of a regime where the order parameter decays when linear theory predicts neutral stability for the incoherent state. We here show that such an effect is far more generic, as soon as phase oscillators couple to their mean field according to their natural frequencies, being then grouped into two distinct populations of conformists and contrarians. We report the analytical solution of this latter situation, which allows determining the critical coupling strength and the stability of the incoherent state, together with extensive numerical simulations that fully support all theoretical predictions. The relevance of our results is discussed in relationship to collective phenomena occurring in social and economical systems. PMID:26657060

  13. Modulational instability regions for coupled Ginzburg-Landau equations with higher order of nonlinearities

    NASA Astrophysics Data System (ADS)

    Zakeri, Gholam-Ali; Yomba, Emmanuel

    2015-06-01

    A generalized (2+1)-dimensional coupled cubic-quintic Ginzburg-Landau equation with higher-order nonlinearities is fully investigated for modulational instability regions. We obtained the constraints that allow the modulational instability (MI) procedure to transform the system under consideration into an analysis of the roots of a polynomial equation of the fourth degree. Because of the complexity of the dispersion relation and its dependence on many parameters, we study numerous examples that are presented graphically. A numerical simulation based on a split-step Fourier method is implemented on the above equation. In addition to the general case, we have considered some special cases that allow us to investigate the behavior of MI in different regions.

  14. Effective thermal conductivity of helium II: from Landau to Gorter-Mellink regimes

    NASA Astrophysics Data System (ADS)

    Sciacca, M.; Jou, D.; Mongiovì, M. S.

    2015-08-01

    The size-dependent and flux-dependent effective thermal conductivity of narrow channels filled with He II is analyzed. The classical Landau evaluation of the effective thermal conductivity of quiescent He II is extended to describe the transition to fully turbulent regime, where the heat flux is proportional to the cubic root of the temperature gradient (Gorter-Mellink regime). To do so, we use an expression for the quantum vortex line density L in terms of the heat flux considering the influence of the walls. From it, and taking into account the friction force of normal component against the vortices, we compute the effective thermal conductivity as a function of the heat flux, and we discuss in detail the corresponding size dependence.

  15. Modulational instability regions for coupled Ginzburg-Landau equations with higher order of nonlinearities.

    PubMed

    Zakeri, Gholam-Ali; Yomba, Emmanuel

    2015-06-01

    A generalized (2+1)-dimensional coupled cubic-quintic Ginzburg-Landau equation with higher-order nonlinearities is fully investigated for modulational instability regions. We obtained the constraints that allow the modulational instability (MI) procedure to transform the system under consideration into an analysis of the roots of a polynomial equation of the fourth degree. Because of the complexity of the dispersion relation and its dependence on many parameters, we study numerous examples that are presented graphically. A numerical simulation based on a split-step Fourier method is implemented on the above equation. In addition to the general case, we have considered some special cases that allow us to investigate the behavior of MI in different regions. PMID:26172769

  16. Generation of pulse trains in nonlinear optical fibers through the generalized complex Ginzburg-Landau equation.

    PubMed

    Latchio Tiofack, Camus G; Mohamadou, Alidou; Kofané, Timoléon C; Moubissi, Alain B

    2009-12-01

    We consider a higher-order complex Ginzburg-Landau equation, with the fourth-order dispersion and cubic-quintic nonlinear terms, which can describe the propagation of an ultrashort subpicosecond or femtosecond optical pulse in an optical fiber system. We investigate the modulational instability (MI) of continuous wave solution of this equation. Several types of modulational instability gains are shown to exist in both the anomalous and normal dispersion regimes. We find that depending on the sign of the fourth-order dispersion coefficient, the MI appears for normal and anomalous dispersion regime. Simulations of the full system demonstrate that the development of the MI leads to establishment of a regular or chaotic array of pulses, a chain of well-separated peaks with continuously growing or decaying amplitudes depending on the sign of the loss/gain coefficient and higher-order dispersions terms. Comparison of the calculations with reported numerical results shows a satisfactory agreement. PMID:20365291

  17. Striped quantum Hall state in a half-filled Landau level

    NASA Astrophysics Data System (ADS)

    Wan, Xin; Yang, Kun

    2016-05-01

    The nature of the fractional quantum Hall state at Landau level filling factor 5/2 remains elusive despite intensive experimental and theoretical work. While the leading theoretical candidates are Moore-Read Pfaffian (Pf) and its particle-hole conjugate anti-Pfaffian (APf), neither received unambiguous experimental support. We show that a state that is intermediate between them, made of alternating stripes of Pf and APf in the bulk, is a viable candidate. Such a state is shown to be incompressible and thus a charge insulator in the bulk, but a heat conductor due to the presence of gapless neutral bulk modes. We argue that the properties of such a state are consistent with existing numerical and experimental work, and discuss possible experimental probes of its presence.

  18. Fractional quantum Hall effect at Landau level filling ν = 4/11

    DOE PAGESBeta

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

    2015-01-09

    In this study, we report low temperature electronic transport results on the fractional quantum Hall effect of composite fermions at Landau level filling ν = 4/11 in a very high mobility and low density sample. Measurements were carried out at temperatures down to 15mK, where an activated magnetoresistance Rxx and a quantized Hall resistance Rxy, within 1% of the expected value of h/(4/11)e2, were observed. The temperature dependence of the Rxx minimum at 4/11 yields an activation energy gap of ~ 7 mK. Developing Hall plateaus were also observed at the neighboring states at ν = 3/8 and 5/13.

  19. Analytical theory of strongly correlated Wigner crystals in the lowest Landau level

    NASA Astrophysics Data System (ADS)

    Rhim, Jun-Won; Jain, Jainendra K.; Park, Kwon

    2015-09-01

    In this work, we present an analytical theory of strongly correlated Wigner crystals (WCs) in the lowest Landau level (LLL) by constructing an approximate, but accurate effective two-body interaction for composite fermions (CFs) participating in the WCs. This requires integrating out the degrees of freedom of all surrounding CFs, which we accomplish analytically by approximating their wave functions by delta functions. This method produces energies of various strongly correlated WCs that are in excellent agreement with those obtained from the Monte Carlo simulation of the full CF crystal wave functions. We compute the compressibility of the strongly correlated WCs in the LLL and predict discontinuous changes at the phase boundaries separating different crystal phases.

  20. Landau damping effects in the synchronization of conformist and contrarian oscillators

    NASA Astrophysics Data System (ADS)

    Qiu, Tian; Zhang, Yue; Liu, Jie; Bi, Hongjie; Boccaletti, S.; Liu, Zonghua; Guan, Shuguang

    2015-12-01

    Two decades ago, a phenomenon resembling Landau damping was described in the synchronization of globally coupled oscillators: the evidence of a regime where the order parameter decays when linear theory predicts neutral stability for the incoherent state. We here show that such an effect is far more generic, as soon as phase oscillators couple to their mean field according to their natural frequencies, being then grouped into two distinct populations of conformists and contrarians. We report the analytical solution of this latter situation, which allows determining the critical coupling strength and the stability of the incoherent state, together with extensive numerical simulations that fully support all theoretical predictions. The relevance of our results is discussed in relationship to collective phenomena occurring in social and economical systems.