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2004-04-30
|
On violation of the Robinson's damping criterion and enhanced cooling of ion, electron and muon beams in storage rings
|
Limits of applicability of the Robinson's damping criterion and the problem
of enhanced cooling of particle beams in storage rings beyond the criterion are
discussed.
|
0404142v6
|
2004-12-28
|
Electron Bernstein waves in spherical tokamak plasmas with "magnetic wells"
|
In addition to traditional regimes with monotonously increasing magnetic
field, regimes with "magnetic wells" also occur in spherical tokamaks (STs).
The magnetic field profile inversion modifies significantly the whole picture
of the wave propagation and damping. Since the magnetic wells may become quite
common with further improvement of ST performance, analysis of such
configurations is of interest for assessment of EBW plasma heating an CD
perspectives. In this paper the basic features of the EBWs propagation and
damping for the second cyclotron harmonic in a slab model are considered.
|
0412173v1
|
2005-08-16
|
Creep-Enhanced Low-Frequency Sensitivity of Seismometers
|
The frequency response of a seismometer is typically assumed to be the
textbook case of a viscous damped, simple harmonic oscillator. Real mechanical
oscillators are not ideal, and the damping at low frequencies, due to internal
friction, is presently too poorly understood to describe from first principles.
Even if the low-level motions were smooth (which they are not), the mean
position of a seismic mass changes because of creep and creep recovery. This
article shows that secondary creep can actually serve to increase the
sensitivity of a seismometer at low frequencies.
|
0508105v1
|
2006-06-22
|
Looking for a time independent Hamiltonian of a dynamical system
|
In this paper we introduce a method for finding a time independent
Hamiltonian of a given dynamical system by canonoid transformation. We also
find a condition that the system should satisfy to have an equivalent time
independent formulation. We study the example of damped oscillator and give the
new time independent Hamiltonian for it, which has the property of tending to
the standard Hamiltonian of the harmonic oscillator as damping goes to zero.
|
0606197v2
|
1996-02-27
|
Effects of Loss and Decoherence on a Simple Quantum Computer
|
We investigate the impact of loss (amplitude damping) and decoherence (phase
damping) on the performance of a simple quantum computer which solves the
one-bit Deutsch problem. The components of this machine are beamsplitters and
nonlinear optical Kerr cells, but errors primarily originate from the latter.
We develop models to describe the effect of these errors on a quantum optical
Fredkin gate. The results are used to analyze possible error correction
strategies in a complete quantum computer. We find that errors due to loss can
be avoided perfectly by appropriate design techniques, while decoherence can be
partially dealt with using projective error correction.
|
9602018v1
|
1996-11-25
|
The Quantum state diffusion model and the driven damped nonlinear oscillator
|
We consider a driven damped anharmonic oscillator which classically leads to
a bistable steady state and to hysteresis. The quantum counterpart for this
system has an exact analytical solution in the steady state which does not
display any bistability or hysteresis. We use quantum state diffusion theory to
describe this system and to provide a new perspective on the lack of hysteresis
in the quantum regime so as to study in detail the quantum to classical
transition. The analysis is also relevant to measurements of a single
periodically driven electron in a Penning trap where hysteresis has been
observed.
|
9611044v1
|
1997-12-02
|
Prevention of dissipation with two particles
|
An error prevention procedure based on two-particle encoding is proposed for
protecting an arbitrary unknown quantum state from dissipation, such as phase
damping and amplitude damping. The schemes, which exhibits manifestation of the
quantum Zeno effect, is effective whether quantum bits are decohered
independently or cooperatively. We derive the working condition of the scheme
and argue that this procedure has feasible practical implementation.
|
9712005v1
|
1998-02-23
|
Caldirola-Kanai Oscillator in Classical Formulation of Quantum Mechanics
|
The quadrature distribution for the quantum damped oscillator is introduced
in the framework of the formulation of quantum mechanics based on the
tomography scheme. The probability distribution for the coherent and Fock
states of the damped oscillator is expressed explicitly in terms of Gaussian
and Hermite polynomials, correspondingly.
|
9802057v1
|
1999-03-22
|
Decoherence - Fluctuation Relation and Measurement Noise
|
We discuss fluctuations in the measurement process and how these fluctuations
are related to the dissipational parameter characterising quantum damping or
decoherence. On the example of the measuring current of the variable-barrier or
QPC problem we show there is an extra noise or fluctuation connected with the
possible different outcomes of a measurement. This noise has an enhanced short
time component which could be interpreted as due to ``telegraph noise'' or
``wavefunction collapses''. Furthermore the parameter giving the the strength
of this noise is related to the parameter giving the rate of damping or
decoherence.
|
9903072v1
|
1999-07-27
|
Nonclassical correlations in damped N-solitons
|
The quantum statistics of damped higher-order optical solitons are analyzed
numerically, using cumulant-expansion techniques in Gaussian approximation. A
detailed analysis of nonclassical properties in both the time and the frequency
domain is given, with special emphasis on the role of absorption. Highly
nonclassical broadband spectral correlation is predicted.
|
9907090v2
|
2001-01-08
|
Cavity-damping-induced transitions in a driven atom-cavity system
|
We investigate the fluorescence spectrum of a two-level atom in a cavity when
the atom is driven by a classical field. We show that forbidden dipole
transitions in the Jaynes-Cummings Ladder structure are induced in the presence
of the cavity damping, which deteriorates the degree of otherwise perfect
destructive interference among the transition channels. With the larger cavity
decay, these transitions are more enhanced.
|
0101036v1
|
2001-06-09
|
Squeezing enhancement by damping in a driven atom-cavity system
|
In a driven atom-cavity coupled system in which the two-level atom is driven
by a classical field, the cavity mode which should be in a coherent state in
the absence of its reservoir, can be squeezed by coupling to its reservoir. The
squeezing effect is enhanced as the damping rate of the cavity is increased to
some extent.
|
0106054v1
|
2001-08-01
|
Decoherence-induced wave packet splitting
|
We provide an intuitive interpretation of the optical Stern-Gerlach effect
(OSGE) in the dressed-state point of view. We also analyze the effect of atomic
damping in an experiment on the OSGE. We show that the atomic damping also
causes the wave packet splitting, in a non-mechanical fashion, as opposed to
the coherent process that is mechanical.
|
0108005v1
|
2001-08-11
|
A Canonical Approach to the Quantization of the Damped Harmonic Oscillator
|
We provide a new canonical approach for studying the quantum mechanical
damped harmonic oscillator based on the doubling of degrees of freedom
approach. Explicit expressions for Lagrangians of the elementary modes of the
problem, characterising both forward and backward time propagations are given.
A Hamiltonian analysis, showing the equivalence with the Lagrangian approach,
is also done. Based on this Hamiltonian analysis, the quantization of the model
is discussed.
|
0108055v2
|
2002-05-09
|
Implementation of quantum maps by programmable quantum processors
|
A quantum processor is a device with a data register and a program register.
The input to the program register determines the operation, which is a
completely positive linear map, that will be performed on the state in the data
register. We develop a mathematical description for these devices, and apply it
to several different examples of processors. The problem of finding a processor
that will be able to implement a given set of mappings is also examined, and it
is shown that while it is possible to design a finite processor to realize the
phase-damping channel, it is not possible to do so for the amplitude-damping
channel.
|
0205050v1
|
2002-08-28
|
Damped Quantum Interference using Stochastic Calculus
|
It is shown how the phase-damping master equation, either in Markovian and
nonMarkovian regimes, can be obtained as an averaged random unitary evolution.
This, apart from offering a common mathematical setup for both regimes, enables
us to solve this equation in a straightforward manner just by solving the
Schrodinger equation and taking the stochastic expectation value of its
solutions after an adequate modification. Using the linear entropy as a figure
of merit (basically the loss of quantum coherence) the distinction of four
kinds of environments is suggested.
|
0208176v1
|
2002-10-31
|
Quantum Markov Channels for Qubits
|
We examine stochastic maps in the context of quantum optics. Making use of
the master equation, the damping basis, and the Bloch picture we calculate a
non-unital, completely positive, trace-preserving map with unequal damping
eigenvalues. This results in what we call the squeezed vacuum channel. A
geometrical picture of the effect of stochastic noise on the set of pure state
qubit density operators is provided. Finally, we study the capacity of the
squeezed vacuum channel to transmit quantum information and to distribute EPR
states.
|
0211001v1
|
2003-01-17
|
Concurrence and foliations induced by some 1-qubit channels
|
We start with a short introduction to the roof concept. An elementary
discussion of phase-damping channels shows the role of anti-linear operators in
representing their concurrence. A general expression for some concurrences is
derived. We apply it to 1-qubit channels of length two, getting induced
foliations of the state space, the optimal decompositions, and the entropy of a
state with respect to these channels. For amplitude-damping channels one
obtains an expression for the Holevo capacity allowing for easy numerical
calculations.
|
0301088v1
|
2003-05-19
|
Statistical Effects in the Multistream Model for Quantum Plasmas
|
A statistical multistream description of quantum plasmas is formulated, using
the Wigner-Poisson system as dynamical equations. A linear stability analysis
of this system is carried out, and it is shown that a Landau-like damping of
plane wave perturbations occurs due to the broadening of the background Wigner
function that arises as a consequence of statistical variations of the wave
function phase. The Landau-like damping is shown to suppress instabilities of
the one- and two-stream type.
|
0305102v1
|
2003-06-28
|
Misbelief and misunderstandings on the non--Markovian dynamics of a damped harmonic oscillator
|
We use the exact solution for the damped harmonic oscillator to discuss some
relevant aspects of its open dynamics often mislead or misunderstood. We
compare two different approximations both referred to as Rotating Wave
Approximation. Using a specific example, we clarify some issues related to
non--Markovian dynamics, non--Lindblad type dynamics, and positivity of the
density matrix.
|
0306193v3
|
2003-11-26
|
Effective damping in the Raman cooling of trapped ions
|
We present a method of treating the interaction of a single three-level ion
with two laser beams. The idea is to apply a unitary transformation such that
the exact transformed Hamiltonian has one of the three levels decoupled for all
values of the detunings. When one takes into account damping, the evolution of
the system is governed by a master equation usually obtained via adiabatic
approximation under the assumption of far-detuned lasers. To go around the
drawbacks of this technique, we use the same unitary transformation to get an
effective master equation.
|
0311183v1
|
2004-06-20
|
Entanglement-assisted classical information capacity of the amplitude damping channel
|
In this paper, we calculate the entanglement-assisted classical information
capacity of amplitude damping channel and compare it with the particular mutual
information which is considered as the entanglement-assisted classical
information capacity of this channel in Ref. 6. It is shown that the difference
between them is very small. In addition, we point out that using partial
symmetry and concavity of mutual information derived from dense coding scheme
one can simplify the calculation of entanglement-assisted classical information
capacities for non-unitary-covariant quantum noisy channels.
|
0406140v1
|
2004-08-13
|
Decoherence versus Dynamical Casimir Effect
|
By means of two simple examples: phase and amplitude damping, the impact of
decoherence on the dynamical Casimir effect is investigated. Even without
dissipating energy (i.e., pure phase damping), the amount of created particles
can be diminished significantly via the coupling to the environment (reservoir
theory) inducing decoherence. For a simple microscopic model, it is
demonstrated that spontaneous decays within the medium generate those problems
-- Rabi oscillations are far more advantageous in that respect. These findings
are particularly relevant in view of a recently proposed experimental
verification of the dynamical Casimir effect. PACS: 42.50.Lc, 03.65.Yz,
03.70.+k, 42.50.Dv.
|
0408087v2
|
2004-10-11
|
Quantizing the damped harmonic oscillator
|
We consider the Fermi quantization of the classical damped harmonic
oscillator (dho). In past work on the subject, authors double the phase space
of the dho in order to close the system at each moment in time. For an
infinite-dimensional phase space, this method requires one to construct a
representation of the CAR algebra for each time. We show that unitary dilation
of the contraction semigroup governing the dynamics of the system is a logical
extension of the doubling procedure, and it allows one to avoid the
mathematical difficulties encountered with the previous method.
|
0410078v1
|
2004-11-18
|
Drastic effects of damping mechanisms on the third-order optical nonlinearity
|
We have investigated the optical response of superradiant atoms, which
undergoes three different damping mechanisms: radiative dissipation
($\gamma_r$), dephasing ($\gamma_d$), and nonradiative dissipation
($\gamma_n$). Whereas the roles of $\gamma_d$ and $\gamma_n$ are equivalent in
the linear susceptibility, the third-order nonlinear susceptibility drastically
depends on the ratio of $\gamma_d$ and $\gamma_n$: When $\gamma_d \ll
\gamma_n$, the third-order susceptibility is essentially that of a single atom.
Contrarily, in the opposite case of $\gamma_d \gg \gamma_n$, the third-order
susceptibility suffers the size-enhancement effect and becomes proportional to
the system size.
|
0411129v1
|
2005-01-19
|
Stabilizing an atom laser using spatially selective pumping and feedback
|
We perform a comprehensive study of stability of a pumped atom laser in the
presence of pumping, damping and outcoupling. We also introduce a realistic
feedback scheme to improve stability by extracting energy from the condensate
and determine its effectiveness. We find that while the feedback scheme is
highly efficient in reducing condensate fluctuations, it usually does not alter
the stability class of a particular set of pumping, damping and outcoupling
parameters.
|
0501101v1
|
2005-06-11
|
Quantum damped oscillator II: Bateman's Hamiltonian vs. 2D Parabolic Potential Barrier
|
We show that quantum Bateman's system which arises in the quantization of a
damped harmonic oscillator is equivalent to a quantum problem with 2D parabolic
potential barrier known also as 2D inverted isotropic oscillator. It turns out
that this system displays the family of complex eigenvalues corresponding to
the poles of analytical continuation of the resolvent operator to the complex
energy plane. It is shown that this representation is more suitable than the
hyperbolic one used recently by Blasone and Jizba.
|
0506091v1
|
2005-06-27
|
Entanglement of pair cat states and teleportation
|
The entanglement of pair cat states in the phase damping channel is studied
by employing the relative entropy of entanglement. It is shown that the pair
cat states can always be distillable in the phase damping channel. Furthermore,
we analyze the fidelity of teleportation for the pair cat states by using joint
measurements of the photon-number sum and phase difference.
|
0506217v1
|
2005-07-21
|
Entanglement versus mixedness for coupled qubits under a phase damping channel
|
Quantification of entanglement against mixing is given for a system of
coupled qubits under a phase damping channel. A family of pure initial joint
states is defined, ranging from pure separable states to maximally entangled
state. An ordering of entanglement measures is given for well defined initial
state amount of entanglement.
|
0507212v2
|
2005-10-20
|
Overdamping by weakly coupled environments
|
A quantum system weakly interacting with a fast environment usually undergoes
a relaxation with complex frequencies whose imaginary parts are damping rates
quadratic in the coupling to the environment, in accord with Fermi's ``Golden
Rule''. We show for various models (spin damped by harmonic-oscillator or
random-matrix baths, quantum diffusion, quantum Brownian motion) that upon
increasing the coupling up to a critical value still small enough to allow for
weak-coupling Markovian master equations, a new relaxation regime can occur. In
that regime, complex frequencies lose their real parts such that the process
becomes overdamped. Our results call into question the standard belief that
overdamping is exclusively a strong coupling feature.
|
0510164v1
|
2006-06-07
|
Comment on "Optimum Quantum Error Recovery using Semidefinite Programming"
|
In a recent paper ([1]=quant-ph/0606035) it is shown how the optimal recovery
operation in an error correction scheme can be considered as a semidefinite
program. As a possible future improvement it is noted that still better error
correction might be obtained by optimizing the encoding as well. In this note
we present the result of such an improvement, specifically for the four-bit
correction of an amplitude damping channel considered in [1]. We get a strict
improvement for almost all values of the damping parameter. The method (and the
computer code) is taken from our earlier study of such correction schemes
(quant-ph/0307138).
|
0606059v1
|
2006-09-19
|
Quantum master equations from classical Lagrangians with two stochastic forces
|
We show how a large family of master equations, describing quantum Brownian
motion of a harmonic oscillator with translationally invariant damping, can be
derived within a phenomenological approach, based on the assumption that an
environment can be simulated by two classical stochastic forces. This family is
determined by three time-dependent correlation functions (besides the frequency
and damping coefficients), and it includes as special cases the known master
equations, whose dissipative part is bilinear with respect to the operators of
coordinate and momentum.
|
0609144v3
|
2006-10-16
|
Local noise can enhance entanglement teleportation
|
Recently we have considered two-qubit teleportation via mixed states of four
qubits and defined the generalized singlet fraction. For single-qubit
teleportation, Badziag {\em et al.} [Phys. Rev. A {\bf 62}, 012311 (2000)] and
Bandyopadhyay [Phys. Rev. A {\bf 65}, 022302 (2002)] have obtained a family of
entangled two-qubit mixed states whose teleportation fidelity can be enhanced
by subjecting one of the qubits to dissipative interaction with the environment
via an amplitude damping channel. Here, we show that a dissipative interaction
with the local environment via a pair of time-correlated amplitude damping
channels can enhance fidelity of entanglement teleportation for a class of
entangled four-qubit mixed states. Interestingly, we find that this enhancement
corresponds to an enhancement in the quantum discord for some states.
|
0610125v1
|
2006-11-24
|
High fidelity transfer of an arbitrary quantum state between harmonic oscillators
|
It is shown that by switching a specific time-dependent interaction between a
harmonic oscillator and a transmission line (a waveguide, an optical fiber,
etc.) the quantum state of the oscillator can be transferred into that of
another oscillator coupled to the distant other end of the line, with a
fidelity that is independent of the initial state of both oscillators. For a
transfer time $T$, the fidelity approaches 1 exponentially in $\gamma T$ where
$\gamma$ is a characteristic damping rate. Hence, a good fidelity is achieved
even for a transfer time of a few damping times. Some implementations are
discussed.
|
0611249v1
|
2006-12-05
|
Quantum Brownian motion and the second law of thermodynamics
|
We consider a single harmonic oscillator coupled to a bath at zero
temperature. As is well known, the oscillator then has a higher average energy
than that given by its ground state. Here we show analytically that for a
damping model with arbitrarily discrete distribution of bath modes and damping
models with continuous distributions of bath modes with cut-off frequencies,
this excess energy is less than the work needed to couple the system to the
bath, therefore, the quantum second law is not violated. On the other hand, the
second law may be violated for bath modes without cut-off frequencies, which
are, however, physically unrealistic models.
|
0612038v1
|
2007-05-08
|
Minimal qudit code for a qubit in the phase-damping channel
|
Using the stabilizer formalism we construct the minimal code into a
D-dimensional Hilbert space (qudit) to protect a qubit against phase damping.
The effectiveness of this code is then studied by means of input-output
fidelity.
|
0705.1099v3
|
2007-05-10
|
Anomalous Diffusion of particles with inertia in external potentials
|
Recently a new type of Kramers-Fokker-Planck Equation has been proposed [R.
Friedrich et al. Phys. Rev. Lett. {\bf 96}, 230601 (2006)] describing anomalous
diffusion in external potentials. In the present paper the explicit cases of a
harmonic potential and a velocity-dependend damping are incorporated. Exact
relations for moments for these cases are presented and the asymptotic
behaviour for long times is discussed. Interestingly the bounding potential and
the additional damping by itself lead to a subdiffussive behaviour, while
acting together the particle becomes localized for long times.
|
0705.1480v1
|
2007-05-31
|
Stability of Solutions to Damped Equations with Negative Stiffness
|
This article concerns the stability of a model for mass-spring systems with
positive damping and negative stiness. It is well known that when the
coefficients are frozen in time the system is unstable. Here we find conditions
on the variable cofficients to prove stability. In particular, we disprove the
believe that if the eigenvalues of the system change slowly in time the system
remains unstable. We extend some of our results for nonlinear systems.
|
0705.4670v1
|
2007-06-13
|
Polymers in a vacuum
|
In a variety of situations, isolated polymer molecules are found in a vacuum
and here we examine their properties. Angular momentum conservation is shown to
significantly alter the average size of a chain and its conservation is only
broken slowly by thermal radiation. The time autocorrelation for monomer
position oscillates with a characteristic time proportional to chain length.
The oscillations and damping are analyzed in detail. Short range repulsive
interactions suppress oscillations and speed up relaxation but stretched chains
still show damped oscillatory time correlations.
|
0706.2001v1
|
2007-07-15
|
Enhancement of Carrier Mobility in Semiconductor Nanostructures by Dielectric Engineering
|
We propose a technique for achieving large improvements in carrier mobilities
in 2- and 1-dimensional semiconductor nanostructures by modifying their
dielectric environments. We show that by coating the nanostructures with
high-$\kappa$ dielectrics, scattering from Coulombic impurities can be strongly
damped. Though screening is also weakened, the damping of Coulombic scattering
is much larger, and the resulting improvement in mobilities of carriers can be
as much as an order of magnitude for thin 2D semiconductor membranes, and more
for semiconductor nanowires.
|
0707.2244v1
|
2007-07-23
|
Causal vs. Noncausal Description of Nonlinear Wave Mixing; Resolving the Damping-Sign Controversy
|
Frequency-domain nonlinear wave mixing processes may be described either
using response functions whereby the signal is generated after all interactions
with the incoming fields, or in terms of scattering amplitudes where all fields
are treated symetrically with no specific time ordering. Closed Green's
function expressions derived for the two types of signals have different
analytical properties. The recent controversy regarding the sign of radiative
damping in the linear (Kramers Heisenberg) formula is put in a broader context.
|
0707.3458v1
|
2007-07-27
|
Excitation of spin dynamics by spin-polarized current in vortex state disks
|
A spin-polarized current with the polarization perpendicular to the plane of
a vortex-state disk results in renormalization of the effective damping for a
given magnetization mode, and the effective damping becomes zero if the current
exceeds a threshold value. The lowest threshold current corresponds to the
lowest frequency vortex gyroscopic mode. For larger values of the current the
dynamic magnetization state is characterized by precession of the vortex around
the dot center with non-small amplitude and higher frequency.
|
0707.4128v1
|
2007-09-11
|
Frequency and damping of the Scissors Mode of a Fermi gas
|
We calculate the frequency and damping of the scissors mode in a classical
gas as a function of temperature and coupling strength. Our results show good
agreement with the main features observed in recent measurements of the
scissors mode in an ultracold gas of $^6$Li atoms. The comparison between
theory and experiment involves no fitting parameters and thus allows an
identification of non-classical effects at and near the unitarity limit.
|
0709.1617v2
|
2007-09-14
|
Strong collisionless damping of the low-velocity branch of electromagnetic wave in plasmas with Maxwellian-like electron velocity distribution function
|
After approximate replacing of Maxwellian distribution exponent with the
rational polynomial fraction we have obtained precise analytical expression for
and calculated the principal value of logarithmically divergent integral in the
electron wave dispersion equation. At the same time our calculations have shown
the presence of strong collisionless damping of the electromagnetic
low-velocity (electron) wave in plasmas with Maxwellian-like electron velocity
distribution function at some small, of the order of several per cents,
differences from Maxwellian distribution in the main region of large electron
densities, however due to the differences in the distribution tail, where
electron density itself is negligibly small.
|
0709.2206v1
|
2007-09-14
|
Plasmons, plasminos and Landau damping in a quasiparticle model of the quark-gluon plasma
|
A phenomenological quasiparticle model is surveyed for 2+1 quark flavors and
compared with recent lattice QCD results. Emphasis is devoted to the effects of
plasmons, plasminos and Landau damping. It is shown that thermodynamic bulk
quantities, known at zero chemical potential, can uniquely be mapped towards
nonzero chemical potential by means of a thermodynamic consistency condition
and a stationarity condition.
|
0709.2262v2
|
2007-10-24
|
Spin dynamics of a trapped spin-1 Bose Gas above the Bose-Einstein transition temperature
|
We study collective spin oscillations in a spin-1 Bose gas above the
Bose-Einstein transition temperature. Starting from the Heisenberg equation of
motion, we derive a kinetic equation describing the dynamics of a thermal gas
with the spin-1 degree of freedom. Applying the moment method to the kinetic
equation, we study spin-wave collective modes with dipole symmetry. The dipole
modes in the spin-1 system are found to be classified into the three type of
modes. The frequency and damping rate are obtained as functions of the peak
density. The damping rate is characterized by three relaxation times associated
with collisions.
|
0710.4419v2
|
2007-11-19
|
Nonlinear mode conversion in monodomain magnetic squares
|
Modifications of spatial distributions of dynamic magnetization corresponding
to spinwave eigenmodes of magnetic squares subjected to a strong microwave
excitation field have been studied experimentally and theoretically. We show
that an increase of the excitation power leads to a nonlinear generation of
long-wavelength spatial harmonics caused by the nonlinear cross coupling
between the eigenmodes. The analysis of the experimental data shows that this
process is mainly governed by the action of the nonlinear spin-wave damping.
This conclusion is further supported by the numerical calculations based on the
complex Ginzburg-Landau equation phenomenologically taking into account the
nonlinear damping.
|
0711.2872v1
|
2007-12-18
|
Weibel Instabilities in Dense Quantum Plasmas
|
The quantum effect on the Weibel instability in an unmagnetized plasma is
presented. Our analysis shows that the quantum effect tends to stabilize the
Weibel instability in the hydrodynamic regime, whereas it produces a new
oscillatory instability in the kinetic regime. A novel effect the quantum
damping, which is associated with the Landau damping, is disclosed. The new
quantum Weibel instability may be responsible for the generation of
non-stationary magnetic fields in compact astrophysical objects as well as in
the forthcoming intense laser-solid density plasma experiments.
|
0712.2874v1
|
2008-01-18
|
A qualitative perspective on the dynamics of a single-Cooper-pair box with a phase-damped cavity
|
In a recent paper Dajka, et.al., [J. Phys. A \textbf{40}, F879 (2007)]
predicted that some composite systems can be entangled forever even if coupled
with a thermal bath. We analyze the transient entanglement of a
single-Cooper-pair box biased by a classical voltage and irradiated by a
quantized field and find the unusual feature that the phase-damped cavity can
lead to a long-lived entanglement. The results show an asymptotic value of the
idempotency defect (concurrence) which embodies coherence loss (entanglement
survival), independent of the interaction development by dependent critically
on environment.
|
0801.2905v2
|
2008-02-28
|
Current driven spin-wave instability triggered by the anomalous Hall effect
|
We studied the effect of strong electric current on spin waves interacting
relativistically with the current. The spin-wave spectrum is calculated at
arbitrary direction of the wave vector. It is shown that the alternating Hall
current generated by the alternating magnetic moment of the spin waves, reduces
the spin-wave damping. At strong enough unpolarized dc current the damping
changes sign, and the spin-wave amplitude starts to increase exponentially fast
with time. The critical current for the spin-wave instability is determined
mainly by the anomalous Hall effect, and can be much smaller than that for the
spin-torque mechanism of instability.
|
0802.4150v1
|
2008-03-31
|
Spectral Modeling of Magnetohydrodynamic Turbulent Flows
|
We present a dynamical spectral model for Large Eddy Simulation of the
incompressible magnetohydrodynamic (MHD) equations based on the Eddy Damped
Quasi Normal Markovian approximation. This model extends classical spectral
Large Eddy Simulations for the Navier-Stokes equations to incorporate general
(non Kolmogorovian) spectra as well as eddy noise. We derive the model for MHD
and show that introducing a new eddy-damping time for the dynamics of spectral
tensors in the absence of equipartition between the velocity and magnetic
fields leads to better agreement with direct numerical simulations, an
important point for dynamo computations.
|
0803.4499v1
|
2008-04-10
|
Trapped Phase-Segregated Bose-Fermi Mixtures and their Collective Excitations
|
Recent progress in the field of ultracold gases has allowed the creation of
phase-segregated Bose-Fermi systems. We present a theoretical study of their
collective excitations at zero temperature. As the fraction of fermion to boson
particle number increases, the collective mode frequencies take values between
those for a fully bosonic and those for a fully fermionic cloud, with damping
in the intermediate region. This damping is caused by fermions which are
resonantly driven at the interface.
|
0804.1759v2
|
2008-04-14
|
Size dependence of multipolar plasmon resonance frequencies and damping rates in simple metal spherical nanoparticles
|
Multipolar plasmon oscillation frequencies and corresponding damping rates
for nanospheres formed of the simplest free-electron metals are studied. The
possibility of controlling plasmon features by choosing the size and dielectric
properties of the sphere surroundings is discussed. Optical properties of the
studied metals are described within the Drude-Sommerfeld model of the
dielectric function with effective parameters acounting for the contribution of
conduction electrons and of interband transitions. No approximation is made in
respect of the size of a particle; plasmon size characteristics are described
rigorously. The results of our experiment on sodium nanodroplets [1] are
compared with the oscillation frequency size dependence of dipole and
quadrupole plasmon.
|
0804.2156v1
|
2008-05-09
|
Spin dynamics in (III,Mn)V ferromagnetic semiconductors: the role of correlations
|
We address the role of correlations between spin and charge degrees of
freedom on the dynamical properties of ferromagnetic systems governed by the
magnetic exchange interaction between itinerant and localized spins. For this
we introduce a general theory that treats quantum fluctuations beyond the
Random Phase Approximation based on a correlation expansion of the Green's
function equations of motion. We calculate the spin susceptibility, spin--wave
excitation spectrum, and magnetization precession damping. We find that
correlations strongly affect the magnitude and carrier concentration dependence
of the spin stiffness and magnetization Gilbert damping.
|
0805.1320v2
|
2008-06-05
|
Thermally Assisted Spin Hall Effect
|
The spin polarized charge transport is systematically analyzed as a thermally
driven stochastic process. The approach is based on Kramers' equation
describing the semiclassical motion under the inclusion of stochastic and
damping forces. Due to the relativistic spin-orbit coupling the damping
experiences a relativistic correction leading to an additional contribution
within the spin Hall conductivity. A further contribution to the conductivity
is originated from the averaged underlying crystal potential, the mean value of
which depends significantly on the electric field. We derive an exact
expression for the electrical conductivity. All corrections are estimated in
lowest order of a relativistic approach and in the linear response regime.
|
0806.0948v1
|
2008-06-13
|
General Solution of the Quantum Damped Harmonic Oscillator II : Some Examples
|
In the preceding paper (arXiv : 0710.2724 [quant-ph]) we have constructed the
general solution for the master equation of quantum damped harmonic oscillator,
which is given by the complicated infinite series in the operator algebra
level. In this paper we give the explicit and compact forms to solutions
(density operators) for some initial values. In particular, the compact one for
the initial value based on a coherent state is given, which has not been given
as far as we know. Moreover, some related problems are presented.
|
0806.2169v1
|
2008-08-09
|
Gilbert Damping in Conducting Ferromagnets I: Kohn-Sham Theory and Atomic-Scale Inhomogeneity
|
We derive an approximate expression for the Gilbert damping coefficient
\alpha_G of itinerant electron ferromagnets which is based on their description
in terms of spin-density-functional-theory (SDFT) and Kohn-Sham quasiparticle
orbitals. We argue for an expression in which the coupling of magnetization
fluctuations to particle-hole transitions is weighted by the spin-dependent
part of the theory's exchange-correlation potential, a quantity which has large
spatial variations on an atomic length scale. Our SDFT result for \alpha_G is
closely related to the previously proposed spin-torque correlation-function
expression.
|
0808.1373v1
|
2008-08-27
|
Entanglement dynamics of two-qubit system in different types of noisy channels
|
In this paper, we study entanglement dynamics of a two-qubit extended
Werner-like state locally interacting with independent noisy channels, i.e.,
amplitude damping, phase damping and depolarizing channels. We show that the
purity of initial entangled state has direct impacts on the entanglement
robustness in each noisy channel. That is, if the initial entangled state is
prepared in mixed instead of pure form, the state may exhibit entanglement
sudden death (ESD) and/or be decreased for the critical probability at which
the entanglement disappear.
|
0808.3690v1
|
2008-09-01
|
Heatons induced by attosecond laser pulses
|
In this paper the dynamics of the interaction of attosecond laser pulses with
matter is investigated. It will be shown that the master equation: modified
Klein-Gordon equation describes the propagation of the heatons. Heatons are the
thermal wave packets. When the duration of the laser pulses is of the order of
attosecond the heaton thermal wave packets are nondispersive objects. For
infinite time the heatons are damped with damping factor of the order of
relaxation time for thermal processes.
|
0809.0204v1
|
2008-10-09
|
Heat conduction in 2D strongly-coupled dusty plasmas
|
We perform non-equilibrium simulations to study heat conduction in
two-dimensional strongly coupled dusty plasmas. Temperature gradients are
established by heating one part of the otherwise equilibrium system to a higher
temperature. Heat conductivity is measured directly from the stationary
temperature profile and heat flux. Particular attention is paid to the
influence of damping effect on the heat conduction. It is found that the heat
conductivity increases with the decrease of the damping rate, while its
magnitude agrees with previous experimental measurement.
|
0810.1623v2
|
2008-10-21
|
Structurally damped plate and wave equations with random point force in arbitrary space dimensions
|
In this paper we consider structurally damped plate and wave equations with
point and distributed random forces. In order to treat space dimensions more
than one, we work in the setting of $L^q$--spaces with (possibly small)
$q\in(1,2)$. We establish existence, uniqueness and regularity of mild and weak
solutions to the stochastic equations employing recent theory for stochastic
evolution equations in UMD Banach spaces.
|
0810.3898v2
|
2008-11-05
|
Spectral function and quasi-particle damping of interacting bosons in two dimensions
|
We employ the functional renormalization group to study dynamical properties
of the two-dimensional Bose gas. Our approach is free of infrared divergences,
which plague the usual diagrammatic approaches, and is consistent with the
exact Nepomnyashchy identity, which states that the anomalous self-energy
vanishes at zero frequency and momentum. We recover the correct infrared
behavior of the propagators and present explicit results for the spectral
line-shape, from which we extract the quasi-particle dispersion and damping.
|
0811.0624v2
|
2008-11-13
|
Existence of weak solutions to the Cauchy problem of a semilinear wave equation with supercritical interior source and damping
|
In this paper we show existence of finite energy solutions for the Cauchy
problem associated with a semilinear wave equation with interior damping and
supercritical source terms. The main contribution consists in dealing with
super-supercritical source terms (terms of the order of $|u|^p$ with $p\geq 5$
in $n=3$ dimensions), an open and highly recognized problem in the literature
on nonlinear wave equations.
|
0811.2151v1
|
2008-11-17
|
Asymptotic stability and blow up for a semilinear damped wave equation with dynamic boundary conditions
|
In this paper we consider a multi-dimensional wave equation with dynamic
boundary conditions, related to the Kelvin-Voigt damping. Global existence and
asymptotic stability of solutions starting in a stable set are proved. Blow up
for solutions of the problem with linear dynamic boundary conditions with
initial data in the unstable set is also obtained.
|
0811.2783v3
|
2008-11-19
|
Weyl laws for partially open quantum maps
|
We study a toy model for "partially open" wave-mechanical system, like for
instance a dielectric micro-cavity, in the semiclassical limit where ray
dynamics is applicable. Our model is a quantized map on the 2-dimensional
torus, with an additional damping at each time step, resulting in a subunitary
propagator, or "damped quantum map". We obtain analogues of Weyl's laws for
such maps in the semiclassical limit, and draw some more precise estimates when
the classical dynamic is chaotic.
|
0811.3134v2
|
2008-12-16
|
A picogram and nanometer scale photonic crystal opto-mechanical cavity
|
We describe the design, fabrication, and measurement of a cavity
opto-mechanical system consisting of two nanobeams of silicon nitride in the
near-field of each other, forming a so-called "zipper" cavity. A photonic
crystal patterning is applied to the nanobeams to localize optical and
mechanical energy to the same cubic-micron-scale volume. The picrogram-scale
mass of the structure, along with the strong per-photon optical gradient force,
results in a giant optical spring effect. In addition, a novel damping regime
is explored in which the small heat capacity of the zipper cavity results in
blue-detuned opto-mechanical damping.
|
0812.2953v1
|
2009-02-12
|
Discrete breathers in a forced-damped array of coupled pendula: Modeling, Computation and Experiment
|
In this work, we present a mechanical example of an experimental realization
of a stability reversal between on-site and inter-site centered localized
modes. A corresponding realization of a vanishing of the Peierls-Nabarro
barrier allows for an experimentally observed enhanced mobility of the
localized modes near the reversal point. These features are supported by
detailed numerical computations of the stability and mobility of the discrete
breathers in this system of forced and damped coupled pendula. Furthermore,
additional exotic features of the relevant model, such as dark breathers are
briefly discussed.
|
0902.2129v1
|
2009-03-08
|
Enhancement of transmission rates in quantum memory channels with damping
|
We consider the transfer of quantum information down a single-mode quantum
transmission line. Such quantum channel is modeled as a damped harmonic
oscillator, the interaction between the information carriers -a train of N
qubits- and the oscillator being of the Jaynes-Cummings kind. Memory effects
appear if the state of the oscillator is not reset after each channel use. We
show that the setup without resetting is convenient in order to increase the
transmission rates, both for the transfer of quantum and classical private
information. Our results can be applied to the micromaser.
|
0903.1424v1
|
2009-03-15
|
A variational approach to strongly damped wave equations
|
We discuss a Hilbert space method that allows to prove analytical
well-posedness of a class of linear strongly damped wave equations. The main
technical tool is a perturbation lemma for sesquilinear forms, which seems to
be new. In most common linear cases we can furthermore apply a recent result
due to Crouzeix--Haase, thus extending several known results and obtaining
optimal analyticity angle.
|
0903.2599v2
|
2009-03-30
|
Damping of Exciton Rabi Rotations by Acoustic Phonons in Optically Excited InGaAs/GaAs Quantum Dots
|
We report experimental evidence identifying acoustic phonons as the principal
source of the excitation-induced-dephasing (EID) responsible for the intensity
damping of quantum dot excitonic Rabi rotations. The rate of EID is extracted
from temperature dependent Rabi rotation measurements of the ground-state
excitonic transition, and is found to be in close quantitative agreement with
an acoustic-phonon model.
|
0903.5278v2
|
2009-05-13
|
Landau damping
|
In this note we present the main results from the recent work
hal-00376547/arXiv:0904.2760, which for the first time establish Landau damping
in a nonlinear context.
|
0905.2167v2
|
2009-05-13
|
Amortissement Landau
|
Dans cette note nous pr\'esentons les principaux r\'esultats du r\'ecent
travail hal-00376547/arXiv:0904.2760, o\`u le ph\'enom\`ene d'amortissement
Landau est pour la premi\`ere fois \'etabli dans un contexte non lin\'eaire.
-----
In this note we present the main results from the recent work hal-00376547 /
arXiv:0904.2760, which for the first time establish Landau damping in a
nonlinear context.
|
0905.2168v2
|
2009-06-27
|
Effect of Bohm potential on a charged gas
|
Bohm's interpretation of Quantum Mechanics leads to the derivation of a
Quantum Kinetic Equation (QKE): in the present work, propagation of waves in
charged quantum gases is investigated starting from this QKE. Dispersion
relations are derived for fully and weakly degenerate fermions and bosons
(these latter above critical temperature), and the differences underlined. Use
of a kinetic equation permits investigation of "Landau-type" damping: it is
found that the presence of damping in fermion gases is dependent upon the
degree of degeneracy, whereas it is always present in boson gases. In fully
degenerate fermions a phenomenon appears that is akin to the "zero sound"
propagation.
|
0906.5061v1
|
2009-07-14
|
Quantum Monty Hall problem under decoherence
|
We study the effect of decoherence on quantum Monty Hall problem under the
influence of amplitude damping, depolarizing and dephasing channels. It is
shown that under the effect of decoherence, there is a Nash equilibrium of the
game in case of depolarizing channel for Alice's quantum strategy. Where as in
case of dephasing noise, the game is not influenced by the quantum channel. For
amplitude damping channel, the Bob's payoffs are found symmetrical with maximum
at p=0.5 against his classical strategy. However, it is worth-mentioning that
in case of depolarizing channel, Bob's classical strategy remains always
dominant against any choice of Alice's strategy.
|
0907.2293v1
|
2009-09-11
|
Energy decay for the damped wave equation under a pressure condition
|
We establish the presence of a spectral gap near the real axis for the damped
wave equation on a manifold with negative curvature. This results holds under a
dynamical condition expressed by the negativity of a topological pressure with
respect to the geodesic flow. As an application, we show an exponential decay
of the energy for all initial data sufficiently regular. This decay is governed
by the imaginary part of a finite number of eigenvalues close to the real axis.
|
0909.2093v1
|
2009-09-12
|
Signature of smooth transition from diabatic to adiabatic states in heavy-ion fusion reactions at deep subbarrier energies
|
We propose a novel extension of the standard coupled-channels framework for
heavy-ion reactions in order to analyze fusion reactions at deep subbarrier
incident energies. This extension simulates a smooth transition between the
diabatic two-body and the adiabatic one-body states. To this end, we damp
gradually the off-diagonal part of the coupling potential, for which the
position of the onset of the damping varies for each eigen channel. We show
that this model accounts well for the steep falloff of the fusion cross
sections for the $^{16}$O+$^{208}$Pb, $^{64}$Ni+$^{64}$Ni, and
$^{58}$Ni+$^{58}$Ni reactions.
|
0909.2298v1
|
2009-10-05
|
Construction of quasi-periodic response solutions in forced strongly dissipative systems
|
We consider a class of ordinary differential equations describing
one-dimensional quasiperiodically forced systems in the presence of large
damping. We give a fully constructive proof of the existence of response
solutions, that is quasi-periodic solutions which have the same frequency
vector as the forcing. This requires dealing with a degenerate implicit
function equation: we prove that the latter has a unique solution, which can be
explicitly determined. As a by-product we obtain an explicit estimate of the
minimal size of the damping coefficient.
|
0910.0746v1
|
2009-10-14
|
Plasmon-phonon Strongly-Coupled Mode in Epitaxial Graphene
|
We report the dispersion measurements, using angle-resolved reflection
electron-energy-loss-spectroscopy (AREELS), on two-dimensional (2D) plasmons in
single and multilayer graphene which couple strongly to surface optical phonon
(FK phonon) modes of silicon carbide substrate. The coupled modes show discrete
dispersion behaviors in the single and bilayer graphene. With increasing
graphene layers on SiC(0001), a transition from plasmon-like dispersion to
phonon-like dispersion is observed. For plasmon-like modes, the dispersion is
strongly damped by electron-hole pair excitations at entering single-particle
continuum, while phonon-like mode is undamped. In the region free of coupling,
the graphene 2D plasmon exhibits acoustic behavior with linear dispersion with
slope and damping determined by the Fermi surface topology.
|
0910.2735v1
|
2009-10-23
|
Collective Enhancement and Suppression of Excitation Decay in Optical Lattices
|
We calculate radiative lifetimes of collective electronic excitations of
atoms in an infinite one dimensional lattice. The translational symmetry along
the lattice restricts the photon wave vector component parallel to the lattice
to the exciton wave number and thus the possible emission directions. The
resulting radiation damping rate and emission pattern of the exciton strongly
deviates from independent atom. For some wave numbers and polarizations the
excitons superradiantly decay very fast, while other excitons show zero
radiation damping rate and form propagating meta-stable excitations. Such
states could be directly coupled via tailored evanescent fields from a nearby
fiber.
|
0910.4501v1
|
2009-10-24
|
Global Attractor for Weakly Damped Forced KdV Equation in Low Regularity on T
|
In this paper we consider the long time behavior of the weakly damped, forced
Korteweg-de Vries equation in the Sololev spaces of the negative indices in the
periodic case. We prove that the solutions are uniformly bounded in
$\dot{H}^s(\T)$ for $s>-\dfrac{1}{2}$. Moreover, we show that the solution-map
possesses a global attractor in $\dot{H}^s(\T)$ for $s>-\dfrac{1}{2}$, which is
a compact set in $H^{s+3}(\T)$.
|
0910.4652v1
|
2009-11-12
|
A new perspective on supersymmetric inflation
|
We consider supersymmetric inflation with the hybrid-type potential. In the
absence of the symmetry that forbids Hubble-induced mass terms, the inflaton
mass will be as large as the Hubble scale during inflation. We consider
gravitational decay of the trigger field as the least decay mode and find that
the damping caused by the dissipation can dominate the friction of the inflaton
when the heavy trigger field is coupled to the inflaton. The dissipative
damping provides a solution to the traditional $\eta$ problem without
introducing additional symmetry and interactions. Considering the spatial
inhomogeneities of the dissipative coefficient, we find that modulated
inflation (modulation of the inflaton velocity) can create significant
curvature perturbations.
|
0911.2350v1
|
2009-12-15
|
Distillability sudden death in qutrit-qutrit systems under amplitude damping
|
Recently it has been discovered that certain two-qutrit entangled states
interacting with global and/or multi-local decoherence undergo distillability
sudden death (DSD). We investigate this phenomenon for qutrit-qutrit systems
interacting with statistically independent zero-temperature reservoirs. We show
that certain initially prepared free-entangled states become bound-entangled in
a finite time due to the action of Markovian dissipative environment. Moreover,
in contrast with local dephasing, simple local unitary transformations can
completely avoid distillability sudden death under amplitude damping.
|
0912.2868v1
|
2009-12-15
|
Global Controllability of Multidimensional Rigid Body by Few Torques
|
We study global controllability of 'rotating' multidimensional rigid body
(MRB) controlled by application of few torques. Study by methods of geometric
control requires analysis of algebraic structure introduced by the quadratic
term of Euler-Frahm equation. We discuss problems, which arise in the course of
this analysis, and establish several global controllability criteria for damped
and non damped cases.
|
0912.2900v1
|
2010-01-16
|
Resonance Damping in Ferromagnets and Ferroelectrics
|
The phenomenological equations of motion for the relaxation of ordered phases
of magnetized and polarized crystal phases can be developed in close analogy
with one another. For the case of magnetized systems, the driving magnetic
field intensity toward relaxation was developed by Gilbert. For the case of
polarized systems, the driving electric field intensity toward relaxation was
developed by Khalatnikov. The transport times for relaxation into thermal
equilibrium can be attributed to viscous sound wave damping via
magnetostriction for the magnetic case and electrostriction for the
polarization case.
|
1001.2845v1
|
2010-02-05
|
Damping Effect of Electromagnetic Radiation and Time-Dependent Schrodinger Equation
|
The inexactness of the time-dependent Schr\"odinger equation of a charged
particle in an external electromagnetic field is discussed in terms of the
damping effect of the radiation. A possible improvement is to add a nonlinear
term representing this effect to the linear Schr\"odinger equation. Conditions
for the nonlinear term are investigated and it is demonstrated that the
obtained nonlinear Schr\"odinger equation may present state evolutions similar
to the wave-function reduction and transitions between stationary states.
|
1002.1116v3
|
2010-02-05
|
Uniform stabilization in weighted Sobolev spaces for the KdV equation posed on the half-line
|
Studied here is the large-time behavior of solutions of the Korteweg-de Vries
equation posed on the right half-line under the effect of a localized damping.
Assuming as in \cite{linares-pazoto} that the damping is active on a set
$(a_0,+\infty)$ with $a_0>0$, we establish the exponential decay of the
solutions in the weighted spaces $L^2((x+1)^mdx)$ for $m\in \N ^*$ and
$L^2(e^{2bx}dx)$ for $b>0$ by a Lyapunov approach. The decay of the spatial
derivatives of the solution is also derived.
|
1002.1127v1
|
2010-03-28
|
Giant magnetic broadening of ferromagnetic resonance in a GMR Co/Ag/Co/Gd quadlayer
|
Both magnetic-resonance damping and the giant magnetoresistance effect have
been predicted to be strongly affected by the local density of states in thin
ferromagnetic films. We employ the antiferromagnetic coupling between Co and Gd
to provide a spontaneous change from parallel to antiparallel alignment of two
Co films. A sharp increase in magnetic damping accompanies the change from
parallel to antiparallel alignment, analogous to resistivity changes in giant
magnetoresistance.
|
1003.5344v1
|
2010-04-04
|
Quantum information reclaiming after amplitude damping
|
We investigate the quantum information reclaim from the environment after
amplitude damping has occurred. In particular we address the question of
optimal measurement on the environment to perform the best possible correction
on two and three dimensional quantum systems. Depending on the dimension we
show that the entanglement fidelity (the measure quantifying the correction
performance) is or is not the same for all possible measurements and uncover
the optimal measurement leading to the maximum entanglement fidelity.
|
1004.0497v1
|
2010-04-09
|
Validity of Landauer's principle in the quantum regime
|
We demonstrate the validity of Landauer's erasure principle in the strong
coupling quantum regime by treating the system-reservoir interaction in a
consistent way. We show that the initial coupling to the reservoir modifies
both energy and entropy of the system and provide explicit expressions for the
latter in the case of a damped quantum harmonic oscillator. These contributions
are related to the Hamiltonian of mean force and dominate in the strong damping
limit. They need therefore to be fully taken into account in any
low-temperature thermodynamic analysis of quantum systems.
|
1004.1599v1
|
2010-04-22
|
Critical exponent for damped wave equations with nonlinear memory
|
We consider the Cauchy problem in $\mathbb{R}^n,$ $n\geq 1,$ for a semilinear
damped wave equation with nonlinear memory. Global existence and asymptotic
behavior as $t\rightarrow\infty$ of small data solutions have been established
in the case when $1\leq n\leq3.$ Moreover, we derive a blow-up result under
some positive data in any dimensional space.
|
1004.3850v4
|
2010-04-27
|
Radiation Damping in a Non-Abelian Strongly-Coupled Gauge Theory
|
We study a `dressed' or `composite' quark in strongly-coupled N=4
super-Yang-Mills (SYM), making use of the AdS/CFT correspondence. We show that
the standard string dynamics nicely captures the physics of the quark and its
surrounding quantum non-Abelian field configuration, making it possible to
derive a relativistic equation of motion that incorporates the effects of
radiation damping. From this equation one can deduce a non-standard dispersion
relation for the composite quark, as well as a Lorentz covariant formula for
its rate of radiation.
|
1004.4912v1
|
2010-05-21
|
Quantization of the Damped Harmonic Oscillator Revisited
|
We return to the description of the damped harmonic oscillator by means of a
closed quantum theory with a general assessment of previous works, in
particular the Bateman-Caldirola-Kanai model and a new model recently proposed
by one of the authors. We show the local equivalence between the two models and
argue that latter has better high energy behavior and is naturally connected to
existing open-quantum-systems approaches.
|
1005.4096v1
|
2010-06-09
|
Dispersion and damping of two-dimensional dust acoustic waves: Theory and Simulation
|
A two-dimensional generalized hydrodynamics (GH) model is developed to study
the full spectrum of both longitudinal and transverse dust acoustic waves (DAW)
in strongly coupled complex (dusty) plasmas, with memory-function-formalism
being implemented to enforce high-frequency sum rules. Results are compared
with earlier theories (such as quasi-localized charge approximation and its
extended version) and with a self-consistent Brownian dynamics simulation. It
is found that the GH approach provides good account, not only for dispersion
relations, but also for damping rates of the DAW modes in a wide range of
coupling strengths, an issue hitherto not fully addressed for dusty plasmas.
|
1006.1799v1
|
2010-07-01
|
Finite time extinction by nonlinear damping for Schrodinger equation
|
We consider the Schrodinger equation on a compact manifold, in the presence
of a nonlinear damping term, which is homogeneous and sublinear. For initial
data in the energy space, we construct a weak solution, defined for all
positive time, which is shown to be unique. In the one-dimensional case, we
show that it becomes zero in finite time. In the two and three-dimensional
cases, we prove the same result under the assumption of extra regularity on the
initial datum.
|
1007.0077v2
|
2010-07-07
|
Spin drag Hall effect in a rotating Bose mixture
|
We show that in a rotating two-component Bose mixture, the spin drag between
the two different spin species shows a Hall effect. This spin drag Hall effect
can be observed experimentally by studying the out-of-phase dipole mode of the
mixture. We determine the damping of this mode due to spin drag as a function
of temperature. We find that due to Bose stimulation there is a strong
enhancement of the damping for temperatures close to the critical temperature
for Bose-Einstein condensation.
|
1007.1088v1
|
2010-08-30
|
Synthesis of electrical networks interconnecting PZT actuators to damp mechanical vibrations
|
This paper proves that it is possible to damp mechanical vibrations of some
beam frames by means of piezoelectric actuators interconnected via passive
networks. We create a kind of electromechanical wave guide where the electrical
velocity group equals the mechanical one thus enabling an electromechanical
energy transfer. Numerical simulations are presented which prove the technical
feasibility of proposed device
|
1008.5112v1
|
2010-09-09
|
The Damped String Problem Revisited
|
We revisit the damped string equation on a compact interval with a variety of
boundary conditions and derive an infinite sequence of trace formulas
associated with it, employing methods familiar from supersymmetric quantum
mechanics. We also derive completeness and Riesz basis results (with
parentheses) for the associated root functions under less smoothness
assumptions on the coefficients than usual, using operator theoretic methods
(rather than detailed eigenvalue and root function asymptotics) only.
|
1009.1858v1
|
2010-09-15
|
Anomalous High-Energy Spin Excitations in La2CuO4
|
Inelastic neutron scattering is used to investigate the collective magnetic
excitations of the high-temperature superconductor parent antiferromagnet
La2CuO4. We find that while the lower energy excitations are well described by
spin-wave theory, including one- and two-magnon scattering processes, the
high-energy spin waves are strongly damped near the (1/2,0) position in
reciprocal space and merge into a momentum dependent continuum. This anomalous
damping indicates the decay of spin waves into other excitations, possibly
unbound spinon pairs.
|
1009.2915v1
|
2010-10-05
|
Damping of dHvA oscillations and vortex-lattice disorder in the peak-effect region of strong type-II superconductors
|
The phenomenon of magnetic quantum oscillations in the superconducting state
poses several questions that still defy satisfactory answers. A key
controversial issue concerns the additional damping observed in the vortex
state. Here, we show results of \mu SR, dHvA, and SQUID magnetization
measurements on borocarbide superconductors, indicating that a sharp drop
observed in the dHvA amplitude just below H_{c2} is correlated with enhanced
disorder of the vortex lattice in the peak-effect region, which significantly
enhances quasiparticle scattering by the pair potential.
|
1010.0929v1
|
2010-10-21
|
Classical behavior of strongly correlated Fermi systems near a quantum critical point. Transport properties
|
The low-temperature kinetics of the strongly correlated electron liquid
inhabiting a solid is analyzed. It is demonstrated that a softly damped branch
of transverse zero sound emerges when several bands cross the Fermi surface
simultaneously near a quantum critical point at which the density of states
diverges. Suppression of the damping of this branch occurs due to a mechanism
analogous to that affecting the phonon mode in solids at room temperature,
giving rise to a classical regime of transport at extremely low temperatures in
the strongly correlated Fermi system.
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1010.4547v1
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