publicationDate stringlengths 1 2.79k | title stringlengths 1 36.5k ⌀ | abstract stringlengths 1 37.3k ⌀ | id stringlengths 9 47 |
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1997-07-23 | Damping of Growth Oscillations in Molecular Beam Epitaxy: A Renormalization Group Approach | The conserved Sine-Gordon Equation with nonconserved shot noise is used to
model homoepitaxial crystal growth. With increasing coverage the renormalized
pinning potential changes from strong to weak. This is interpreted as a
transition from layer-by-layer to rough growth. The associated length and time
scales are ident... | 9707247v1 |
1997-09-30 | AC transport with reservoirs of finite width | The linear response conductance coefficients are calculated in the scattering
approach at finite frequency, damping and magnetic field for a microstructure
in which the reservoirs are modeled as quantum wire leads of infinite length
but finite width. Independently of frequency, inelastic scattering causes
subbands with... | 9709332v2 |
1997-10-08 | Spin and orbital excitation spectrum in the Kugel-Khomskii model | We discuss spin and orbital ordering in the twofold orbital degenerate
superexchange model in three dimensions relevant to perovskite transition metal
oxides. We focus on the particular point on the classical phase diagram where
orbital degeneracy is lifted by quantum effects exclusively. Dispersion and
damping of the ... | 9710070v1 |
1997-10-21 | Sound waves and the absence of Galilean invariance in flocks | We study a model of flocking for a very large system (N=320,000) numerically.
We find that in the long wavelength, long time limit, the fluctuations of the
velocity and density fields are carried by propagating sound modes, whose
dispersion and damping agree quantitatively with the predictions of our
previous work usin... | 9710222v1 |
1997-12-20 | Collective Excitations in High-Temperature Superconductors | Collective, low-energy excitations in quasi-two-dimensional d-wave
superconductors are analyzed. While the long-range Coulomb interaction shifts
the charge-density-wave and phase modes up to the plasma energy, the
spin-density-wave excitation that arises due to a strong local
electron-electron repulsion can propagate a... | 9712255v1 |
1998-01-25 | Excitations of a Bose-Einstein Condensate at Non-Zero Temperature: A Study of Zeroth, First and Second Sound | Collective excitations of a dilute Bose gas were probed above and below the
Bose-Einstein condensation temperature. The temperature dependencies of the
frequency and damping rates of condensate oscillations indicate significant
interactions between the condensate and the thermal cloud. Hydrodynamic
oscillations of the ... | 9801262v1 |
1998-02-17 | Escape from a metastable well under a time-ramped force | Thermally activated escape of an over-damped particle from a metastable well
under the action of a time-ramped force is studied. We express the mean first
passage time (MFPT) as the solution to a partial differential equation, which
we solve numerically for a model case. We discuss two approximations of the
MFPT, one o... | 9802182v1 |
1998-03-02 | On temperature versus doping phase diagram of high critiical temperature superconductors | The attempt to describe the bell-shape dependence of the critical temperature
of high-$T_{c}$ superconductors on charge carriers density is made. Its linear
increase in the region of small densities (underdoped regime) is proposed to
explain by the role of the order parameter phase 2D fluctuations which become
less at ... | 9803011v1 |
1998-03-02 | Evolution of Hole and Spin Dynamics in High Temperature Superconductors within the Small Hole Density Limit of the t-J Model | The evolution of hole and spin dynamics in high temperature superconductors
is studied within the self-consistent noncrossing approximation of the t-J
model in the small hole density limit. As the doping concentration is
increased, long-range electron correlations disappear rapidly and the
quasiparticle energy band bec... | 9803016v1 |
1998-04-14 | The dynamics of component separation in a binary mixture of Bose-Einstein condensates | We present studies of the time-evolution of a two-component system of
Bose-Einstein condensates (BEC) in the |F=1, mf=-1> and |2,1> spin states of
Rb-87. The two condensates are created with a well-defined relative phase and
complete spatial overlap. In subsequent evolution they undergo complex relative
motions which t... | 9804138v1 |
1998-04-17 | Relaxation Processes in Clouds of Trapped Bosons above the Bose-Einstein Condensation Temperature | We present a unified account of damping of low-lying collective modes and of
relaxation of temperature anisotropies in a trapped Bose gas in the
collisionless regime. By means of variational techniques, we show that the
relaxation times for the two situations are closely related to the simplest
variational estimate of ... | 9804193v1 |
1998-05-01 | Hot electron transport in Ballistic Electron Emission Spectroscopy: band structure effects and k-space currents | Using a Green's function approach, we investigate band structure effects in
the BEEM current distribution in reciprocal space. In the elastic limit, this
formalism provides a 'parameter free' solution to the BEEM problem. At low
temperatures, and for thin metallic layers, the elastic approximation is enough
to explain ... | 9805007v1 |
1998-05-25 | Measurements of Relative Phase in Binary Mixtures of Bose-Einstein Condensates | We have measured the relative phase of two Bose-Einstein condensates (BEC)
using a time-domain separated-oscillatory-field condensate interferometer. A
single two-photon coupling pulse prepares the double condensate system with a
well-defined relative phase; at a later time, a second pulse reads out the
phase differenc... | 9805327v1 |
1998-08-04 | Quantum energy flow, dissipation and decoherence in mesoscopic dielectric structures | We first present a summary of recent results concerning the phononic energy
transport properties of mesoscopic, suspended dielectric wires. We then discuss
some related open problems concerning the fundamental lower limits on the
vibrational damping rates of submicron-sized cantilever structures and also the
possibilit... | 9808032v1 |
1998-08-17 | Exact General Solutions to Extraordinary N-body Problems | We solve the N-body problems in which the total potential energy is any
function of the mass-weighted root-mean-square radius of the system of N point
masses. The fundamental breathing mode of such systems vibrates non-linearly
for ever. If the potential is supplemented by any function that scales as the
inverse square... | 9808173v1 |
1998-08-19 | Collective Modes in High-Temperature Superconductors | The role of collective modes in various experiments on the cuprates is
investigated. We calculate the neutron scattering, photoemission (ARPES), and
Raman scattering intensities below $T_c$ within the fluctuation-exchange (FLEX)
approximation for the two-dimensional Hubbard model. It is shown that the large
peak in the... | 9808210v1 |
1998-09-03 | Dynamics of two interacting Bose-Einstein condensates | We analize the dynamics of two trapped interacting Bose-Einstein condensates
and indentify two regimes for the evolution: the regime of slow periodic
oscillations and the regime of strong non-linear mixing leading to the damping
of the relative motion of the condensates. We compare our predictions with an
experiment re... | 9809061v2 |
1998-10-05 | Quantum critical point with competing propagating and diffusive spin excitations | Feedback effects due to spin fluctuation induced precursors in the fermionic
quasiparticle spectrum are taken into account in the description of a quantum
critical point of itinerant spin systems. A correlation length dependent spin
damping occurs, leading to a dynamical scaling with z\approx 1 which
non-trivially comp... | 9810041v1 |
1998-10-30 | The Markov approximation for the atomic output coupler | The regions of validity of the Markov approximation for the coupling of atoms
out of an atomic trap are determined. We consider radio-frequency output
coupling in the presence of gravity and collisional repulsion, and Raman output
coupling. The Markov approximation is crucial in most theoretical descriptions
of an atom... | 9810413v1 |
1998-11-18 | A Stochastic Liouvillian Algorithm to Simulate Dissipative Quantum Dynamics With Arbitrary Precision | An exact and efficient new method to simulate dynamics in dissipative quantum
systems is presented. A stochastic Liouville equation, deduced from Feynman and
Vernon's path-integral expression of the reduced density matrix, is used to
describe the exact dynamics at any dissipative strength and for arbitrarily low
temper... | 9811277v1 |
1998-12-01 | Polarons in Wurtzite Nitride Semiconductors | Polaron binding energy and effective mass are calculated for semiconductors
with wurtzite crystalline structure from the first order electron-phonon
corrections to the self-energy. A recently introduced Frohlich-like
electron-phonon interaction Hamiltonian which accounts for the LO and TO
polarizations mixing due to th... | 9812021v1 |
1998-12-24 | Straight cracks in dynamic brittle fracture | We study the dynamics of cracks in brittle materials when the velocity of the
crack is comparable to the sound velocity by means of lattice simulations.
Inertial and damped dynamics are analyzed. It is shown that dissipation
strongly influences the shape of the crack. While inertial cracks are highly
unstable, dissipat... | 9812391v1 |
1999-02-08 | On the Reconstruction of Random Media using Monte Carlo Methods | A simulated annealing algorithm is applied to the reconstruction of
two-dimensional porous media with prescribed correlation functions. The
experimental correlation function of an isotropic sample of Fontainebleau
sandstone and a synthetic correlation function with damped oscillations are
used in the reconstructions. T... | 9902096v1 |
1999-03-18 | On the electron-energy loss spectra and plasmon resonance in cuprates | The consequences of the non-Drude charge response in the normal state of
cuprates and the effect of the layered structure on electron-energy loss
spectra are investigated, both for experiments in the transmission and the
reflection mode. It is shown that in the intermediate doping regime the plasmon
resonance has to be... | 9903287v1 |
1999-04-26 | Magnon Damping by magnon-phonon coupling in Manganese Perovskites | Inelastic neutron scattering was used to systematically investigate the
spin-wave excitations (magnons) in ferromagnetic manganese perovskites. In
spite of the large differences in the Curie temperatures ($T_C$s) of different
manganites, their low-temperature spin waves were found to have very similar
dispersions with ... | 9904372v1 |
1999-04-28 | Collective oscillations of a classical gas confined in harmonic traps | Starting from the Boltzmann equation we calculate the frequency and the
damping of the monopole and quadrupole oscillations of a classical gas confined
in an harmonic potential. The collisional term is treated in the relaxation
time approximation and a gaussian ansatz is used for its evaluation. Our
approach provides a... | 9904409v1 |
1999-05-11 | Magnon Broadening Effect by Magnon-Phonon Interaction in Colossal Magnetoresistance Manganites | In order to study the magnetic excitation behaviors in colossal
magnetoresistance manganites, a magnon-phonon interacting system is
investigated. Sudden broadening of magnon linewidth is obtained when a magnon
branch crosses over an optical phonon branch. Onset of the broadening is
approximately determined by the magno... | 9905133v2 |
1999-06-03 | Effects of noise and nonlocal interactions in nonlinear dynamics of molecular systems | We show that the NLS systems with multiplicative noise, nonlinear damping and
nonlocal dispersion exhibit a variety of interesting effects which may be
useful for modelling the dynamical behavior of one- and two-dimensional
molecular systems. | 9906050v1 |
1999-06-20 | Tunneling-Assisted Acoustic Plasmon-Quasiparticle Excitation Resonances in Coupled Q1D Electron Gases | We show that a weak non-resonant tunneling between two quantum wires leads to
splitting of the acoustic plasmon mode at finite wavevector. Two gaps open up
in the dipersion of the acoustic plasmon mode when its frequency is close to
the frequencies of the quasiparticle excitations. In contrast to the Laudau
damping of ... | 9906306v1 |
1999-07-06 | New type of antiferromagnetic polaron and bipolaron in HTc - superconductors | The possibility of formation of a new type of polaron based on the quantum
aniferromagnet (AF) model is reported. We take into account exchange
interactions between localized d-d spins of the AF, as well as the p-d
interaction of the AF with p-carriers.
The energy minimum is found when maximum charge density occurs o... | 9907081v1 |
1999-08-01 | Comment on "quantum theory for mesosocopic electric circuits". Cond-mat/9907171 and cond-mat/9606206 | In references cond-mat/9907171 and cond-mat/9606206 (Phys.Rev.B.53, 4927
(1996)) by You-Quan Li and Bin Chen, was considered a mesoscopic LC circuit
with charge discreteness. So, it was proposed a finite difference Schroedinger
equation for the charge time behavior. In this comment, we generalize the
corresponding meso... | 9908012v1 |
1999-09-03 | Wave Function Mismatches and Coulomb Drag | In this paper, I study the topological excitations in a pairing state in
double layer systems at Landau level filling factor $\nu=1/2$ in the presence
of disorders. Due to mismatches between single particle wave functions of
composite Fermions in different layers, the sensitivity of the Chern number of
the pairing stat... | 9909051v2 |
1999-10-06 | Collisional relaxation in diffuse clouds of trapped bosons | The damping of collective modes and the relaxation of temperature
anisotropies in a trapped Bose gas is determined at temperatures above the
Bose-Einstein condensation temperature in the collisionless regime. We
demonstrate for both cases how the effects of collisions may be treated
perturbatively and calculate relaxat... | 9910081v1 |
1999-10-22 | Driven Tunneling Dynamics: Bloch-Redfield Theory versus Path Integral Approach | In the regime of weak bath coupling and low temperature we demonstrate
numerically for the spin-boson dynamics the equivalence between two widely used
but seemingly different roads of approximation, namely the path integral
approach and the Bloch-Redfield theory. The excellent agreement between these
two methods is cor... | 9910359v2 |
1999-10-27 | A Novel Longitudinal Mode in the Coupled Quantum Chain Compound KCuF3 | Inelastic neutron scattering measurements are reported that show a new
longitudinal mode in the antiferromagnetically ordered phase of the spin-1/2
quasi-one-dimensional antiferromagnet KCuF3. This mode signals the cross-over
from one-dimensional to three-dimensional behavior and indicates a reduction in
the ordered sp... | 9910459v1 |
1999-11-12 | Observation of the scissors mode and superfluidity of a trapped Bose-Einstein condensed gas | We report the observation of the scissors mode of a Bose-Einstein condensed
gas of 87^Rb atoms in a magnetic trap, which gives direct evidence of
superfluidity in this system. The scissors mode of oscillation is excited by a
sudden rotation of the anisotropic trapping potential. For a gas above T_c
(normal fluid) we de... | 9911195v1 |
1999-11-19 | Transport in a One-Dimensional Superfluid: Quantum Nucleation of Phase Slips | We present an analytical derivation for the quantum decay rate of the
superflow through a weak link in a one-dimensional Bose-Einstein-condensate.
The effective action for the phase difference across the link reduces to that
of a massive particle with damping subject to a periodic potential. We find an
algebraic flow-p... | 9911301v1 |
1999-11-26 | Kadanoff-Baym Equations with Initial Correlations | The Kadanoff-Baym equations (KBE) are usually derived under the assumption of
the weakening of initial correlations (Bogolyubov's condition) and, therefore,
fail to correctly describe the short time behavior. We demonstrate that this
assumption is not necessary. Using functional derivatives techniques, we
present a str... | 9911429v1 |
1999-12-08 | Thermodynamical fluctuations and photo-thermal shot noise in gravitational wave antennae | Thermodynamical fluctuations of temperature in mirrors of gravitational wave
antennae are transformed through thermal expansion coefficient into additional
noise. This source of noise, which may also be interpreted as fluctuations due
to thermoelastic damping, may not be neglected and leads to the necessity to
reexamin... | 9912139v1 |
2000-01-25 | Motion of dark solitons in trapped Bose-Einstein condensates | We use a multiple time scale boundary layer theory to derive the equation of
motion for a dark (or `grey') soliton propagating through an effectively
one-dimensional cloud of Bose-Einstein condensate, assuming only that the
background density and velocity vary slowly on the soliton scale. We show that
solitons can exhi... | 0001360v1 |
2000-02-01 | Fractional Kramers Equation | We introduce a fractional Kramers equation for a particle interacting with a
thermal heat bath and external non-linear force field. For the force free case
the velocity damping follows the Mittag-Leffler relaxation and the diffusion is
enhanced. The equation obeys the generalized Einstein relation, and its
stationary s... | 0002020v1 |
2000-02-20 | Impurity spin dynamics in 2D antiferromagnets and superconductors | We discuss the universal theory of localized impurities in the paramagnetic
state of 2D antiferromagnets where the spin gap is assumed to be significantly
smaller than a typical exchange energy. We study the impurity spin
susceptibility near the host quantum transition from a gapped paramagnet to a
Neel state, and we c... | 0002316v1 |
2000-03-01 | Short, Medium and Long Range Spatial Correlations in Simple Glasses | Local stresses and pressures always exist in glasses.
In this letter we consider their effects on the structure and structural
correlations in simple glasses. We find that extreme values of local pressures
are related to well defined local structures. The correlations related to these
extreme stresses extend to full ... | 0003006v1 |
2000-03-03 | Heat Conduction and Charge Ordering in Perovskite Manganites, Nickelates and Cuprates | We discuss heat transport in hole-doped manganites, nickelates and cuprates
for which real-space charge ordering has been observed. We survey the thermal
transport response to charge order in the various materials and the associated
structural modifications, particularly distortions of the metal-oxygen
polyhedra associ... | 0003047v1 |
2000-04-08 | Asymptotic states in long Josephson junctions in an external magnetic field | Asymptotic states in long Josephson junctions are investigated in an external
magnetic field. We show that a choice one of the solution of the stationary
Ferrell-Prange equation can carry be out with use of an asymptotic solution of
the sine-Gordon equation and that an evolution to that stable solution occurs
by passin... | 0004120v1 |
2000-04-20 | Peculiarities of anharmonic lattice dynamics and thermodynamics of alkaline-earth metals | The calculations are performed for a broad range of the properties of Ca and
Sr in the fcc and bcc phases. A detailed information on the magnitude and
character of temperature dependence of anharmonic effects in the lattice
dynamics over the entire Brillouin zone (frequency shifts and phonon damping,
Gruneisen paramete... | 0004353v1 |
2000-06-20 | Final Generalization of the Three Coupled Oscillator Model in the Crystal Optical Activity | In this paper we generalize the quantum mechanical model of three coupled
oscillators because of its usage in the crystal optical activity. Using this
model we can include the influence of all essential couplings between single
oscillators which represent the molecules or atoms of optically active crystals
belonging fo... | 0006299v1 |
2000-07-03 | Dynamics of Fluctuating Bose-Einstein Condensates | We present a generalized Gross-Pitaevskii equation that describes also the
dissipative dynamics of a trapped partially Bose condensed gas. It takes the
form of a complex nonlinear Schr\"odinger equation with noise. We consider an
approximation to this Langevin field equation that preserves the correct
equilibrium for b... | 0007026v1 |
2000-08-14 | Manifestation of superfluidity in an evolving Bose-condensed gas | We study the generation of excitations due to an ''impurity''(static
perturbation) placed into an oscillating Bose-condensed gas in the
time-dependent trapping field. It is shown that there are two regions for the
position of the local perturbation. In the first region the condensate flows
around the ''impurity'' witho... | 0008207v1 |
2000-10-04 | Measurement of the energy dependence of phase relaxation by single electron tunneling | Single electron tunneling through a single impurity level is used to probe
the fluctuations of the local density of states in the emitter. The energy
dependence of quasi-particle relaxation in the emitter can be extracted from
the damping of the fluctuations of the local density of states (LDOS). At
larger magnetic fie... | 0010070v1 |
2000-10-08 | Role of entropy barriers for diffusion in the periodic potential | Diffusion of a particle in the N-dimensional external potential which is
periodic in one dimension and unbounded in the other N-1 dimensions is
investigated. We find an analytical expression for the overdamped diffusion and
study numerically the cases of moderate and low damping. We show that in the
underdamped limit, ... | 0010125v1 |
2000-10-12 | Friction in a solid lubricant film | Molecular dynamics study of a thin (one to five layers) lubricant film
between two substrates in moving contact are performed using Langevin equations
with an external damping coefficient depending on distance and velocity of
atoms relative the substrates, motivated by microscopic configurations. They
show that the min... | 0010185v1 |
2001-01-15 | A classical field method for time dependent Bose condensed gases | We propose a method to study the time evolution of Bose condensed gases
perturbed from an initial thermal equilibrium, based on the Wigner
representation of the $N$-body density operator. We show how to generate a
collection of random classical fields sampling the initial Wigner distribution
in the number conserving Bo... | 0101210v2 |
2001-01-19 | Ghost excitonic insulator transition in layered graphite | Some unusual properties of layered graphite, including a linear energy
dependence of the quasiparticle damping and weak ferromagnetism at low doping,
are explained as a result of the proximity of a single graphene sheet to the
excitonic insulator phase which can be further stabilized in a doped system of
many layers st... | 0101306v4 |
2001-01-25 | Comment on "Critical spin dynamics of the 2D quantum Heisenberg antiferromagnets: Sr2CuO2Cl2 and Sr2Cu3O4Cl2" | We compare the neutron measurements of Kim et al. (cond-mat/0012239) on
two-dimensional, S=1/2 antiferromagnets with the continuum quasiclassical
theory of S. Sachdev and O.A. Starykh (cond-mat/9904354). The damping of the
lowest energy spin excitations is characterized by a dimensionless number whose
temperature depen... | 0101394v1 |
2001-01-29 | Enhancement of mobility by periodically modulating the slanting slope of a washboard potential | Average mobility of very feebly damped particles in tilted periodic
potentials is considered. Under the combined action of thermal fluctuations and
small temporal modulation of the tilt of the potential the particles, in the
small tilt range, become more mobile than without modulation. The enhancement
of mobility depen... | 0101425v1 |
2001-02-26 | Relaxation time of weakly interacting superparamagnets | The relaxation time of weakly interacting classical spins is calculated by
introducing the averages of the local dipolar field, obtained by thermodynamic
perturbation theory, in a rigorous expression for the single-spin
thermoactivation rate in a weak but arbitrarily oriented field. At low
temperatures the non-trivial ... | 0102472v1 |
2001-03-02 | Penetration Depth Measurements in MgB_2: Evidence for Unconventional Superconductivity | We have measured the magnetic penetration depth of the recently discovered
binary superconductor MgB_2 using muon spin rotation and low field
$ac$-susceptibility. From the damping of the muon precession signal we find the
penetration depth at zero temperature is about 85nm. The low temperature
penetration depth shows a... | 0103060v1 |
2001-05-09 | An echo of an exciting light pulse in quantum wells | The non-sinusoidal character oscillations appear in the transmitted,
reflected and absorbed light fluxes when light pulses irradiate a semiconductor
quantum well (QW), containing a large number of the equidistant energy levels
of electronic excitations. A damping echo of the exciting pulse appears through
the time inte... | 0105198v1 |
2001-05-18 | Controlled Generation of Dark Solitons with Phase Imprinting | The generation of dark solitons in Bose-Einstein condensates with phase
imprinting is studied by mapping it into the classic problem of a damped driven
pendulum. We provide simple but powerful schemes of designing the phase imprint
for various desired outcomes. We derive a formula for the number of dark
solitons genera... | 0105377v1 |
2001-05-22 | Transition from Collisionless to Hydrodynamic Behaviour in an Ultracold Atomic Gas | Relative motion in a two-component, trapped atomic gas provides a sensitive
probe of interactions. By studying the lowest frequency excitations of a two
spin-state gas confined in a magnetic trap, we have explored the transition
from the collisionless to the hydrodynamic regime. As a function of collision
rate, we obse... | 0105441v1 |
2001-05-23 | Finite-temperature simulations of the scissors mode in Bose-Einstein condensed gases | The dynamics of a trapped Bose-condensed gas at finite temperatures is
described by a generalized Gross-Pitaevskii equation for the condensate order
parameter and a semi-classical kinetic equation for the thermal cloud, solved
using $N$-body simulations. The two components are coupled by mean fields as
well as collisio... | 0105465v1 |
2001-06-25 | Collective Excitations of Dilute Bose-Fermi Superfluid Mixtures | Using the effective action formalism, we investigate collective excitations
of a dilute mixture of a Bose gas and a two component Fermi gas when both
bosons and fermions have undergone superfluid transitions. We show that there
is a repulsion between Bogoliubov and Anderson modes, which has important
implications inclu... | 0106503v1 |
2001-07-10 | The formation of vortex loops (strings) in continuous phase transitions | The formation of vortex loops (global cosmic strings) in an O(2) linear sigma
model in three spatial dimensions is analyzed numerically. For over-damped
Langevin dynamics we find that defect production is suppressed by an
interaction between correlated domains that reduces the effective spatial
variation of the phase o... | 0107188v2 |
2001-07-20 | Theory of sound propagation in superfluid-filled porous media | The theory of sound propagation in macroscopically isotropic and homogeneous
porous media saturated with superfluid ^4He(so-called He II) has been developed
neglecting all damping processes. The case when the normal fluid component is
locked inside a porous medium by viscous forces is investigated in detail. It
is show... | 0107438v3 |
2001-08-11 | Spin dynamics from time-dependent spin density-functional theory | We derive the spin-wave dynamics of a magnetic material from the
time-dependent spin density functional theory in the linear response regime.
The equation of motion for the magnetization includes, besides the static spin
stiffness, a "Berry curvature" correction and a damping term. A gradient
expansion scheme based on ... | 0108193v1 |
2001-09-20 | Aging effects in the quantum dynamics of a dissipative free particle: non-ohmic case | We report new results related to the two-time dynamics of the coordinate of a
quantum free particle, damped through its interaction with a fractal thermal
bath (non-ohmic coupling $\sim\omega^\delta$ with $0<\delta<1$ or
$1<\delta<2)$. When the particle is localized, its position does not age. When
it undergoes anomalo... | 0109368v1 |
2001-09-26 | Slow relaxation, confinement, and solitons | Millisecond crystal relaxation has been used to explain anomalous decay in
doped alkali halides. We attribute this slowness to Fermi-Pasta-Ulam solitons.
Our model exhibits confinement of mechanical energy released by excitation.
Extending the model to long times is justified by its relation to solitons,
excitations pr... | 0109483v1 |
2001-10-09 | Quantum decay rates for driven barrier potentials in the strong friction limit | Quantum decay rates for barrier potentials driven by external stochastic and
periodic forces in the strong damping regime are studied. Based on the recently
derived quantum Smoluchowski equation [Phys. Rev. Lett. {\bf 87}, 086802
(2001)] explicit analytical and numerical results are presented for the case of
the resona... | 0110169v1 |
2001-10-10 | Ferromagnetism and disorder: A dynamical mean-field study | We investigate ferromagnetism in the periodic Anderson model with diagonal
disorder. Using dynamical mean-field theory in combination with the modified
perturbation theory, the disorder can be included in the calculation
consistently, which turns out to be equivalent to the CPA method. Disorder
generally reduces the Cu... | 0110209v1 |
2001-10-29 | Long-Range Coherence in a Mesoscopic Metal near a Superconducting Interface | We identify the different contributions to quantum interference in a
mesoscopic metallic loop in contact with two superconducting electrodes. At low
temperature, a flux-modulated Josephson coupling is observed with strong
damping over the thermal length L_{T}. At higher temperature, the
magnetoresistance exhibits large... | 0110584v1 |
2001-11-05 | Dynamical Behaviour of Fine Granular Glass/Bronze Mixtures under Vertical Vibration | We report the behaviour of mixtures of fine bronze and glass spheres under
sinusoidal vertical vibration. Depending upon the ratio of their diameters and
the amplitude and frequency of the vibration, we observe the formation of sharp
separation boundaries between glass-rich and bronze-rich phases, the absence of
gross ... | 0111064v1 |
2001-11-23 | The transverse breathing mode of an elongated Bose-Einstein condensate | We study experimentally the transverse monopole mode of an elongated rubidium
condensate. Due to the scaling invariance of the non-linear Schr\"odinger
(Gross-Pitaevski) equation, the oscillation is monochromatic and sinusoidal at
short times, even under strong excitation. For ultra-low temperatures, the
quality factor... | 0111455v1 |
2002-01-08 | Feromagnetic "$π$"-junctions | We investigate Josephson coupling through a ferromagnetic thin film using
Superconductor-Insulator-Ferromagnet-Superconductor planar junctions. Damped
oscillations of the critical current are observed as a function of the
ferromagnetic layer thickness. We show that they result from the exchange
energy gained or lost by... | 0201104v2 |
2002-03-08 | Exact c-number Representation of Non-Markovian Quantum Dissipation | The reduced dynamics of a quantum system interacting with a linear heat bath
finds an exact representation in terms of a stochastic Schr{\"o}dinger
equation. All memory effects of the reservoir are transformed into noise
correlations and mean-field friction. The classical limit of the resulting
stochastic dynamics is s... | 0203193v1 |
2002-05-01 | Amplitude coda of classical waves in disordered media | The propagation of classical waves in the presence of a disordered medium is
studied. We consider wave pulses containing a broad range of frequencies in
terms of the configurationally averaged Green function of the system. Damped
oscillations in the time-dependent response trailing behind the direct arrival
of the puls... | 0205014v1 |
2002-05-14 | Finite temperature spectral function of Mott insulators and CDW States | We calculate the low temperature spectral function of one-dimensional
incommensurate charge density wave (CDW) states and half-filled Mott insulators
(MI). At $T=0$ there are two dispersing features associated with the spin and
charge degrees of freedom respectively. We show that already at very low
temperatures (compa... | 0205294v2 |
2002-07-26 | Experimental Investigation of Microwave Enhanced Cotunneling in SET Transistors | Cotunneling is an important error process in the application of single
electron tunneling devices for metrological and electronic applications. Here
we present an experimental investigation of the theory for adiabatic
enhancement of cotunneling by coherent microwaves. The dependence is
investigated as function of tempe... | 0207639v1 |
2002-07-26 | Two-level system with a thermally fluctuating transfer matrix element: Application to the problem of DNA charge transfer | Charge transfer along the base-pair stack in DNA is modeled in terms of
thermally-assisted tunneling between adjacent base pairs. Central to our
approach is the notion that tunneling between fluctuating pairs is rate-limited
by the requirement of their optimal alignment. We focus on this aspect of the
process by modeli... | 0207654v1 |
2002-08-27 | Sound Propagation in Nematic Fermi Liquid | We study the longitudinal sound propagation in the electronic nematic Fermi
liquid where the Fermi surface is distorted due to the spontaneously broken
rotational symmetry. The behavior of the sound wave in the nematic ordered
state is dramatically different from that in the isotropic Fermi liquid. The
collective modes... | 0208524v1 |
2002-09-06 | Nonequilibrium Fluctuations and Decoherence in Nanomechanical Devices Coupled to the Tunnel Junction | We analyze the dynamics of a nanomechanical oscillator coupled to an
electrical tunnel junction with an arbitrary voltage applied to the junction
and arbitrary temperature of electrons in leads. We obtain the explicit
expressions for the fluctuations of oscillator position, its
damping/decoherence rate, and the current... | 0209149v1 |
2002-09-09 | Decoherence and Relaxation of a Quantum Bit in the Presence of Rabi Oscillations | Dissipative dynamics of a quantum bit driven by a strong resonant field and
interacting with a heat bath is investigated. We derive generalized Bloch
equations and find modifications of the qubit's damping rates caused by Rabi
oscillations. Nonequilibrium decoherence of a phase qubit inductively coupled
to a LC-circuit... | 0209217v4 |
2002-09-10 | Effective Field Theory for Goldstone Bosons in Nonrelativistic Superfluids | We consider nonrelativistic superfluids where the global U(1)-symmetry is
spontaneously broken. At sufficiently long wavelengths, the relevant degree of
freedom is the massless Goldstone mode and we construct an effective low energy
theory for the Goldstone boson. The damping rate of collective excitations at
low energ... | 0209243v1 |
2002-11-06 | Quadrupole Oscillation of a Single-Vortex Condensate: Evidence for Kelvin Modes | We study the two transverse quadrupole modes of a cigar-shaped Bose-Einstein
condensate with a single centered vortex. We show that the counter-rotating
mode is more strongly damped than in the absence of a vortex, whereas the
co-rotating mode is not affected appreciably by the vortex. We interpret this
result as a dec... | 0211101v1 |
2002-11-19 | Beliaev Damping and Kelvin Mode Spectroscopy of a Condensate in the Presence of a Vortex Line | It is demonstrated theoretically that the counter-rotating quadrupole mode in
a vortex of Bose-Einstein condensates can decay into a pair of Kelvin modes via
Beliaev process. We calculate the spectral weight of density-response function
within Bogoliubov framework, taking account of both Beliaev and Landau
processes. G... | 0211396v1 |
2002-11-20 | Vortex dynamics in the nonlinear Schrodinger equation | The dynamics of a two-dimensional vortex are analyzed within the framework of
the nonlinear Schrodinger equation. Both a bare vortex and a vortex with an
external mass trapped in a finite-sized core are considered. The bare vortex
motion is found to be damped at all frequencies, while the finite core has a
single reson... | 0211424v1 |
2002-12-05 | Activated escape over oscillating barriers: The case of many dimensions | We present a novel path-integral method for the determination of
time-dependent and time-averaged reaction rates in multidimensional,
periodically driven escape problems at weak thermal noise. The so obtained
general expressions are evaluated explicitly for the situation of a
sinusoidally driven, damped particle with i... | 0212117v1 |
2002-12-05 | Dynamic stiffness of spin valves | The dynamics of the magnetic order parameters of
ferromagnet/normal-metal/ferromagnet spin valves and isolated ferromagnets may
be very different. We investigate the role of the nonequilibrium spin-current
exchange between the ferromagnets in the magnetization precession and
switching. We find a (low-temperature) criti... | 0212130v2 |
2003-01-15 | Effects of parametric noise on a nonlinear oscillator | We study a model of a nonlinear oscillator with a random frequency and derive
the asymptotic behavior of the probability distribution function when the noise
is white. In the small damping limit, we show that the physical observables
grow algebraically with time before the dissipative time scale is reached, and
calcula... | 0301259v1 |
2003-01-30 | Quantum critical point in CuGeO3 doped with magnetic impurities | Using high frequency (up to 450 GHz) ESR and low temperature specific heat
measurements we find that insertion of 1% Fe and 2% Co damps spin-Peierls and
Neel transitions and for T<30K gives rise to onset of a quantum critical
behaviour characteristic for a random dimer Griffiths phase. | 0301595v1 |
2003-02-13 | Steering of a Bosonic Mode with a Double Quantum Dot | We investigate the transport and coherence properties of a double quantum dot
coupled to a single damped boson mode. Our numerically results reveal how the
properties of the boson distribution can be steered by altering parameters of
the electronic system such as the energy difference between the dots.
Quadrature ampli... | 0302265v1 |
2003-02-18 | Flow equation renormalization of a spin-boson model with a structured bath | We discuss the dynamics of a spin coupled to a damped harmonic oscillator.
This system can be mapped to a spin-boson model with a structured bath, i.e.
the spectral function of the bath has a resonance peak. We diagonalize the
model by means of infinitesimal unitary transformations (flow equations),
thereby decoupling ... | 0302357v1 |
2003-03-28 | Models for generation 1/f noise | Simple analytically solvable models are proposed exhibiting 1/f spectrum in
wide range of frequency. The signals of the models consist of pulses (point
process) which interevent times fluctuate about some average value, obeying an
autoregressive process with very small damping. The power spectrum of the
process can be ... | 0303603v1 |
2003-04-08 | Exploiting environmental resonances to enhance qubit quality factors | We discuss dephasing times for a two-level system (including bias) coupled to
a damped harmonic oscillator. This system is realized in measurements on
solid-state Josephson qubits. It can be mapped to a spin-boson model with a
spectral function with an approximately Lorentzian resonance. We diagonalize
the model by mea... | 0304177v1 |
2003-05-08 | Resonant nature of phonon-induced damping of Rabi oscillations in quantum dots | Optically controlled coherent dynamics of charge (excitonic) degrees of
freedom in a semiconductor quantum dot under the influence of lattice dynamics
(phonons) is discussed theoretically. We show that the dynamics of the lattice
response in the strongly non-linear regime is governed by a semiclassical
resonance betwee... | 0305165v2 |
2003-05-23 | Phase field approach for modeling intracellular dynamics | We introduce a phase field approach for diffusion inside and outside a closed
cell with damping and with source terms at the interface. The method is
compared to exact solutions (where possible) and the more traditional finite
element method. It is shown to be very accurate, easy to implement and
computationally inexpe... | 0305577v1 |
2003-06-11 | Phase locking in quantum and classical oscillators: polariton condensates, lasers, and arrays of Josephson junctions | We connect three phenomena in which a coherent electromagnetic field could be
generated: polariton condensation, phase-locking in arrays of underdamped
Josephson junctions, and lasing. All these phenomena have been described using
Dicke-type models of spins coupled to a single photon mode. These descriptions
may be dis... | 0306268v1 |
2003-06-26 | Nanoscience with Attosecond Laser Pulses | In this paper the interaction of attosecond laser pulses with matter is
investigated. The scattering and potential motion of heat carriers as well as
the external force are considered. Depending on the ratio of the scatterings
and potential motion the heat transport is described by the thermal forced
Klein-Gordon or th... | 0306671v1 |
2003-06-27 | Origin of the "Waterfall" Effect in Phonon Dispersion of Relaxor Perovskites | Inelastic neutron scattering study of the perovskite relaxor ferroelectric
PZN:8%PT elucidates the origin of the previously reported unusual kink on the
low frequency transverse phonon dispersion curve (known as "waterfall" effect).
We show that its position depends on the choice of the Brillouin zone and that
the rela... | 0306692v1 |
2003-07-04 | Comment on "Estimate of the vibrational frequencies of spherical virus particles" | This comment corrects some errors which appeared in the calculation of an
elastic sphere eigenenergies. As a result, the symmetry of the mode having the
lowest frequency is changed. Also a direction for calculating the damping of
these modes for embedded elastic spheres is given. | 0307112v2 |
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