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2004-09-27
|
Damping of electromagnetic waves due to electron-positron pair production
|
The problem of the backreaction during the process of electron-positron pair
production by a circularly polarized electromagnetic wave propagating in a
plasma is investigated. A model based on the relativistic Boltzmann-Vlasov
equation with a source term corresponding to the Schwinger formula for the pair
creation rate is used. The damping of the wave, the nonlinear up-shift of its
frequency due to the plasma density increase and the effect of the damping on
the wave polarization and on the background plasma acceleration are
investigated as a function of the wave amplitude.
|
0409301v1
|
2005-10-25
|
Infrared behavior of the dispersion relations in high-temperature scalar QED
|
We investigate the infrared properties of the next-to-leading-order
dispersion relations in scalar quantum electrodynamics at high temperature in
the context of hard-thermal-loop perturbation theory. Specifically, we
determine the damping rate and the energy for scalars with ultrasoft momenta.
We show by explicit calculations that an early external-momentum expansion,
before the Matsubara sum is performed, gives exactly the same result as a late
one. The damping rate is obtained up to fourth order included in the ultrasoft
momentum and the energy up to second order. The damping rate is found sensitive
in the infrared whereas the energy not.
|
0510330v1
|
2006-11-09
|
Lepton asymmetry in the primordial gravitational wave spectrum
|
Effects of neutrino free streaming is evaluated on the primordial spectrum of
gravitational radiation taking both neutrino chemical potential and masses into
account. The former or the lepton asymmetry induces two competitive effects,
namely, to increase anisotropic pressure, which damps the gravitational wave
more, and to delay the matter-radiation equality time, which reduces the
damping. The latter effect is more prominent and a large lepton asymmetry would
reduce the damping. We may thereby be able to measure the magnitude of lepton
asymmetry from the primordial gravitational wave spectrum.
|
0611121v1
|
2005-03-17
|
A New Approach to Canonical Quantization of the Radiation Damping
|
Inspired in some works about quantization of dissipative systems, in
particular of the damped harmonic oscillator\cite{MB,RB,12}, we consider the
dissipative system of a charge interacting with its own radiation, which
originates the radiation damping (RD). Using the indirect Lagrangian
representation we obtained a Lagrangian formalism with a Chern-Simons-like
term. A Hamiltonian analysis is also done, what leads to the quantization of
the system.
|
0503135v1
|
2003-09-15
|
Eigenfrequencies and expansions for damped wave equations
|
We study eigenfrequencies and propagator expansions for damped wave equations
on compact manifolds. Under the assumption of geometric control, the propagator
is shown to admit an expansion in terms of finitely many eigenmodes near the
real axis, with an error term exponentially decaying in time. In the presence
of a nondegenerate elliptic closed geodesic not meeting the support of the
damping coefficient, we show that there exists a sequence of eigenfrequencies
converging rapidly to the real axis. In the case of Zoll manifolds, we show
that the propagator can be expanded in terms of clusters of the
eigenfrequencies in the entire spectral band.
|
0309250v1
|
2004-06-02
|
Instability results for the damped wave equation in unbounded domains
|
We extend some previous results for the damped wave equation in bounded
domains in Euclidean spaces to the unbounded case. In particular, we show that
if the damping term is of the form $\alpha a$ with bounded $a$ taking on
negative values on a set of positive measure, then there will always exist
unbounded solutions for sufficiently large positive $\alpha$.
In order to prove these results, we generalize some existing results on the
asymptotic behaviour of eigencurves of one-parameter families of Schrodinger
operators to the unbounded case, which we believe to be of interest in their
own right.
|
0406041v1
|
1997-07-20
|
Effects of gluon damping rate on the viscosity coefficient of the quark-gluon plasma at finite chemical potential
|
By considering the Debye screening and damping rate of gluons, the viscosity
coefficient of the quark-gluon plasma was evaluated via real-time finite
temperature QCD in the relaxation time approximation at finite temperature and
chemical potential . The results show that both the damping rate and the
chemical potential cause considerable enhancements to the viscosity coefficient
of hot dense quark-gluon plasma.
|
9707033v1
|
2002-12-11
|
Rotational Damping and Compound Formation in Warm Rotating Nuclei
|
The rotational damping width \Gamma_{rot} and the compound damping width
\Gamma_{comp} are two fundamental quantities that characterize rapidly rotating
compound nuclei having finite thermal excitation energy. A two-component
structure in the strength function of consecutive E2 transitions reflects the
two widths, and it causes characteristic features in the double and triple
gamma-ray spectra. We discuss a new method to extract experimentally values of
\Gamma_{rot} and \Gamma_{comp}. The first preliminary result of this method is
presented.
|
0212050v1
|
2003-07-27
|
Chaos and rotational damping in particle-rotor model
|
The onset of chaos and the mechanism of rotational damping are studied in an
exactly soluble particle-rotor model. It is shown that the degree of chaoticity
as inferred from the statistical measures is closely related to the onset of
rotational damping obtained using the model Hamiltonian.
|
0307104v2
|
1997-07-10
|
Supersymmetric partner chirping of Newtonian free damping
|
We connect the classical free damping cases by means of Rosner's construction
in supersymmetric quantum mechanics. Starting with the critical damping, one
can obtain in the underdamping case a chirping of instantaneous physical
frequency \omega ^{2}(t) \propto \omega_{u}^{2}sech^2(\omega_{u}t), whereas in
the overdamped case the "chirping" is of the (unphysical) type \omega
^{2}(t)\propto\omega_{o}^{2}sec^{2}(\omega_{o}t), where \omega_{u}$ and
$\omega_{o} are the underdamped and overdamped frequency parameters,
respectively
|
9707012v4
|
2000-04-10
|
Ermakov-Lewis angles for one-parameter supersymmetric families of Newtonian free damping modes
|
We apply the Ermakov-Lewis procedure to the one-parameter damped modes
\tilde{y} recently introduced by Rosu and Reyes, which are related to the
common Newtonian free damping modes y by the general Riccati solution [H.C.
Rosu and M. Reyes, Phys. Rev. E 57, 4850 (1998), physics/9707019]. In
particular, we calculate and plot the angle quantities of this approach that
can help to distinguish these modes from the common y modes
|
0004014v4
|
2002-10-29
|
Model of Internal Friction Damping in Solids
|
A model for harmonic oscillator damping due to the internal friction of
solids has been developed, based on considerations of a long period pendulum.
The assumption of a complex elastic modulus to describe stress-strain
hysteresis in the support structure of the pendulum yields an expression for
the figure of merit Q that agrees with many experiments involving material
damping. As such, the approximations of this linear model stand in contrast
with common theory.
|
0210121v1
|
2003-06-11
|
Nonlinear Damping of the 'Linear' Pendulum
|
This study shows that typical pendulum dynamics is far from the simple
equation of motion presented in textbooks. A reasonably complete damping model
must use nonlinear terms in addition to the common linear viscous expression.
In some cases a nonlinear substitute for assumed linear damping may be more
appropriate. Even for exceptional cases where all nonlinearity may be ignored,
it is shown that viscous dissipation involves subtleties that can lead to huge
errors when ignored.
|
0306081v1
|
2004-08-19
|
Beyond the Linear Damping Model for Mechanical Harmonic Oscillators
|
The steady state motion of a folded pendulum has been studied using
frequencies of drive that are mainly below the natural (resonance) frequency of
the instrument. Although the free-decay of this mechanical oscillator appears
textbook exponential, the steady state behavior of the instrument for
sub-resonance drive can be remarkably complex. Although the response cannot be
explained by linear damping models, the general features can be understood with
the nonlinear, modified Coulomb damping model developed by the author.
|
0408091v1
|
1998-01-28
|
Phenomenological damping in trapped atomic Bose-Einstein condensates
|
The method of phenomenological damping developed by Pitaevskii for
superfluidity near the $\lambda$ point is simulated numerically for the case of
a dilute, alkali, inhomogeneous Bose-condensed gas near absolute zero. We study
several features of this method in describing the damping of excitations in a
Bose-Einstein condensate. In addition, we show that the method may be employed
to obtain numerically accurate ground states for a variety of trap potentials.
|
9801064v1
|
1998-04-06
|
Optimal quantum codes for preventing collective amplitude damping
|
Collective decoherence is possible if the departure between quantum bits is
smaller than the effective wave length of the noise field. Collectivity in the
decoherence helps us to devise more efficient quantum codes. We present a class
of optimal quantum codes for preventing collective amplitude damping to a
reservoir at zero temperature. It is shown that two qubits are enough to
protect one bit quantum information, and approximately $L+ 1/2 \log_2((\pi
L)/2)$ qubits are enough to protect $L$ qubit information when $L$ is large.
For preventing collective amplitude damping, these codes are much more
efficient than the previously-discovered quantum error correcting or avoiding
codes.
|
9804014v1
|
2000-01-12
|
Antibunching effect of the radiation field in a microcavity with a mirror undergoing heavily damping oscillation
|
The interaction between the radiation field in a microcavity with a mirror
undergoing damping oscillation is investigated. Under the heavily damping
cases, the mirror variables are adiabatically eliminated.
The the stationary conditions of the system are discussed. The small
fluctuation approximation around steady values is applied to analysis the
antibunching effect of the cavity field. The antibunching condition is given
under two limit cases.
|
0001036v1
|
2002-02-15
|
Decoherence of Quantum Damped Oscillators
|
Quantum dissipation is studied within two model oscillators, the
Caldirola-Kanai (CK) oscillator as an open system with one degree of freedom
and the Bateman-Feshbach-Tikochinsky (BFT) oscillator as a closed system with
two degrees of freedom. Though these oscillators describe the same classical
damped motion, the CK oscillator retains the quantum coherence, whereas the
damped subsystem of the BFT oscillator exhibits both quantum decoherence and
classical correlation. Furthermore the amplified subsystem of the BFT
oscillator shows the same degree of quantum decohernce and classical
correlation.
|
0202089v1
|
2002-12-05
|
Time correlated quantum amplitude damping channel
|
We analyze the problem of sending classical information through qubit
channels where successive uses of the channel are correlated. This work extends
the analysis of C. Macchiavello and G. M. Palma to the case of a non-Pauli
channel - the amplitude damping channel. Using the channel description outlined
in S. Daffer, et al, we derive the correlated amplitude damping channel. We
obtain a similar result to C. Macchiavello and G. M. Palma, that is, that under
certain conditions on the degree of channel memory, the use of entangled input
signals may enhance the information transmission compared to the use of product
input signals.
|
0212032v1
|
2003-09-29
|
Damping rates of the atomic velocity in Sisyphus cooling
|
We present a theoretical and experimental study of the damping process of the
atomic velocity in Sisyphus cooling. The relaxation rates of the atomic kinetic
temperature are determined for a 3D lin$\perp$lin optical lattice. We find that
the damping rates of the atomic temperature depend linearly on the optical
pumping rate, for a given depth of the potential wells. This is at variance
with the behavior of the friction coefficient as calculated from the spatial
diffusion coefficients within a model of Brownian motion. The origin of this
different behavior is identified by distinguishing the role of the trapped and
traveling atoms.
|
0309209v1
|
2005-06-01
|
Quantum damped oscillator I: dissipation and resonances
|
Quantization of a damped harmonic oscillator leads to so called Bateman's
dual system. The corresponding Bateman's Hamiltonian, being a self-adjoint
operator, displays the discrete family of complex eigenvalues. We show that
they correspond to the poles of energy eigenvectors and the corresponding
resolvent operator when continued to the complex energy plane. Therefore, the
corresponding generalized eigenvectors may be interpreted as resonant states
which are responsible for the irreversible quantum dynamics of a damped
harmonic oscillator.
|
0506007v1
|
2005-10-19
|
The damped harmonic oscillator in deformation quantization
|
We propose a new approach to the quantization of the damped harmonic
oscillator in the framework of deformation quantization. The quantization is
performed in the Schr\"{o}dinger picture by a star-product induced by a
modified "Poisson bracket". We determine the eigenstates in the damped regime
and compute the transition probability between states of the undamped harmonic
oscillator after the system was submitted to dissipation.
|
0510150v1
|
2006-04-28
|
The characteristic function of optical evolution
|
The master equation of quantum optical density operator is transformed to the
equation of characteristic function. The parametric amplification and amplitude
damping as well as the phase damping are considered. The solution for the most
general initial quantum state is obtained for parametric amplification and
amplitude damping. The purity of one mode Gaussian system and the entanglement
of two mode Gaussian system are studied.
|
0604208v4
|
2007-01-13
|
Wave-particle duality in the damped harmonic oscillator
|
Quantization of the damped harmonic oscillator is taken as leitmotiv to
gently introduce elements of quantum probability theory for physicists. To this
end, we take (graduate) students in physics as entry level and explain the
physical intuition and motivation behind the, sometimes overwhelming, math
machinery of quantum probability theory.
The main text starts with the quantization of the (undamped) harmonic
oscillator from the Heisenberg and Schroedinger point of view. We show how both
treatments are special instances of a quantum probabilistic quantization
procedure: the second quantization functor. We then apply the second
quantization functor to the damped harmonic oscillator and interpret the
quantum dynamics of the position and energy operator as stochastic processes.
|
0701082v1
|
2007-04-11
|
Time dependence of joint entropy of oscillating quantum systems
|
The time dependent entropy (or Leipnik's entropy) of harmonic and damped
harmonic oscillators is extensively investigated by using time dependent wave
function obtained by the Feynman path integral method. Our results for simple
harmonic oscillator are in agrement with the literature. However, the joint
entropy of damped harmonic oscillator shows remarkable discontinuity with time
for certain values of damping factor. According to the results, the envelop of
the joint entropy curve increases with time monotonically. This results is the
general properties of the envelop of the joint entropy curve for quantum
systems.
|
0704.1370v3
|
2007-06-30
|
The squeezed generalized amplitude damping channel
|
Squeezing of a thermal bath introduces new features absent in an open quantum
system interacting with an uncorrelated (zero squeezing) thermal bath. The
resulting dynamics, governed by a Lindblad-type evolution, extends the concept
of a generalized amplitude damping channel, which corresponds to a dissipative
interaction with a purely thermal bath. Here we present the Kraus
representation of this map, which we call the squeezed generalized amplitude
damping channel. As an application of this channel to quantum information, we
study the classical capacity of this channel.
|
0707.0059v2
|
2007-07-09
|
Memory in a nonlocally damped oscillator
|
We analyze the new equation of motion for the damped oscillator. It differs
from the standard one by a damping term which is nonlocal in time and hence it
gives rise to a system with memory. Both classical and quantum analysis is
performed. The characteristic feature of this nonlocal system is that it breaks
local composition low for the classical Hamiltonian dynamics and the
corresponding quantum propagator.
|
0707.1199v2
|
2007-07-20
|
Dynamics of Bloch Oscillations in Disordered Lattice Potentials
|
We present a detailed analysis of the dynamics of Bloch oscillations of
Bose-Einstein condensates in disordered lattice potentials. Due to the disorder
and the interparticle interactions these oscillations undergo a dephasing,
reflected in a damping of the center of mass oscillations, which should be
observable under realistic experimental conditions. The interplay between
interactions and disorder is far from trivial, ranging from an
interaction-enhanced damping due to modulational instability for strong
interactions, to an interaction-reduced damping due to a dynamical screening of
the disorder potential.
|
0707.3131v1
|
2007-09-14
|
Damping of field-induced chemical potential oscillations in ideal two-band compensated metals
|
The field and temperature dependence of the de Haas-van Alphen oscillations
spectrum is studied for an ideal two-dimensional compensated metal. It is shown
that the chemical potential oscillations, involved in the frequency
combinations observed in the case of uncompensated orbits, are strongly damped
and can even be suppressed when the effective masses of the electron- and
hole-type orbits are the same. When magnetic breakdown between bands occurs,
this damping is even more pronounced and the Lifshits-Kosevich formalism
accounts for the data in a wide field range.
|
0709.2223v2
|
2007-09-14
|
Update on Ion Studies
|
The effect of ions has received one of the highest priorities in R&D for the
damping rings of the International Linear Collider(ILC). It is detrimental to
the performance of the electron damping ring. In this note, an update
concerning the ion studies for the ILC damping ring is given. We investigate
the gap role and irregular fill pattern in the ring.The ion density reduction
in different fills is calculated analytically. Simulation results are also
presented.
|
0709.2248v1
|
2007-10-03
|
Stability of a Nonlinear Axially Moving String With the Kelvin-Voigt Damping
|
In this paper, a nonlinear axially moving string with the Kelvin-Voigt
damping is considered. It is proved that the string is stable, i.e., its
transversal displacement converges to zero when the axial speed of the string
is less than a certain critical value. The proof is established by showing that
a Lyapunov function corresponding to the string decays to zero exponentially.
It is also shown that the string displacement is bounded when a bounded
distributed force is applied to it transversally. Furthermore, a few open
problems regarding the stability and stabilization of strings with the
Kelvin-Voigt damping are stated.
|
0710.0872v1
|
2007-10-15
|
General Solution of the Quantum Damped Harmonic Oscillator
|
In this paper the general solution of the quantum damped harmonic oscillator
is given.
|
0710.2724v4
|
2008-02-21
|
Identification of Test Structures for Reduced Order Modeling of the Squeeze Film Damping in Mems
|
In this study the dynamic behaviour of perforated microplates oscillating
under the effect of squeeze film damping is analyzed. A numerical approach is
adopted to predict the effects of damping and stiffness transferred from the
surrounding ambient air to oscillating structures ; the effect of hole's cross
section and plate's extension is observed. Results obtained by F.E.M. models
are compared with experimental measurements performed by an optical
interferometric microscope.
|
0802.3076v1
|
2008-03-14
|
Current-induced noise and damping in non-uniform ferromagnets
|
In the presence of spatial variation of the magnetization direction, electric
current noise causes a fluctuating spin-transfer torque that increases the
fluctuations of the ferromagnetic order parameter. By the
fluctuation-dissipation theorem, the equilibrium fluctuations are related to
the magnetization damping, which in non-uniform ferromagnets acquires a
nonlocal tensor structure. In biased ferromagnets, shot noise can become the
dominant contribution to the magnetization noise at low temperatures.
Considering spin spirals as a simple example, we show that the current-induced
noise and damping is significant.
|
0803.2175v1
|
2008-04-23
|
Ion acoustic waves in the plasma with the power-law q-distribution in nonextensive statistics
|
We investigate the dispersion relation and Landau damping of ion acoustic
waves in the collisionless magnetic-field-free plasma if it is described by the
nonextensive q-distributions of Tsallis statistics. We show that the increased
numbers of superthermal particles and low velocity particles can explain the
strengthened and weakened modes of Landau damping, respectively, with the
q-distribution. When the ion temperature is equal to the electron temperature,
the weakly damped waves are found to be the distributions with small values of
q.
|
0804.3732v1
|
2008-07-23
|
Tunneling-induced damping of phase coherence revivals in deep optical lattices
|
We consider phase coherence collapse and revival in deep optical lattices,
and calculate within the Bose-Hubbard model the revival amplitude damping
incurred by a finite tunneling coupling of the lattice wells (after sweeping
from the superfluid to the Mott phase). Deriving scaling laws for the
corresponding decay of first-order coherence revival in terms of filling
factor, final lattice depth, and number of tunneling coupling partners, we
estimate whether revival-damping related to tunneling between sites can be or
even has already been observed in experiment.
|
0807.3627v2
|
2008-07-31
|
Generalized Theory of Landau Damping
|
Collisionless damping of electrical waves in plasma is investigated in the
frame of the classical formulation of the problem. The new principle of
regularization of the singular integral is used. The exact solution of the
corresponding dispersion equation is obtained. The results of calculations lead
to existence of discrete spectrum of frequencies and discrete spectrum of
dispersion curves. Analytical results are in good coincidence with results of
direct mathematical experiments. Key words: Foundations of the theory of
transport processes and statistical physics; Boltzmann physical kinetics;
damping of plasma waves, linear theory of wave`s propagation PACS: 67.55.Fa,
67.55.Hc
|
0807.5007v1
|
2008-07-31
|
Scattering Theory of Gilbert Damping
|
The magnetization dynamics of a single domain ferromagnet in contact with a
thermal bath is studied by scattering theory. We recover the
Landau-Liftshitz-Gilbert equation and express the effective fields and Gilbert
damping tensor in terms of the scattering matrix. Dissipation of magnetic
energy equals energy current pumped out of the system by the time-dependent
magnetization, with separable spin-relaxation induced bulk and spin-pumping
generated interface contributions. In linear response, our scattering theory
for the Gilbert damping tensor is equivalent with the Kubo formalism.
|
0807.5009v1
|
2008-08-05
|
Radiation damping, noncommutativity and duality
|
In this work, our main objective is to construct a N=2 supersymmetric
extension of the nonrelativistic $(2+1)$-dimensional model describing the
radiation damping on the noncommutative plane with scalar (electric) and vector
(magnetic) interactions by the N=2 superfield technique. We also introduce a
dual equivalent action to the radiation damping one using the Noether
procedure.
|
0808.0694v2
|
2008-08-28
|
Gilbert Damping in Conducting Ferromagnets II: Model Tests of the Torque-Correlation Formula
|
We report on a study of Gilbert damping due to particle-hole pair excitations
in conducting ferromagnets. We focus on a toy two-band model and on a four-band
spherical model which provides an approximate description of ferromagnetic
(Ga,Mn)As. These models are sufficiently simple that disorder-ladder-sum vertex
corrections to the long-wavelength spin-spin response function can be summed to
all orders. An important objective of this study is to assess the reliability
of practical approximate expressions which can be combined with electronic
structure calculations to estimate Gilbert damping in more complex systems.
|
0808.3923v1
|
2008-10-06
|
Local existence and exponential growth for a semilinear damped wave equation with dynamic boundary conditions
|
In this paper we consider a multi-dimensional damped semiliear wave equation
with dynamic boundary conditions, related to the Kelvin-Voigt damping. We
firstly prove the local existence by using the Faedo-Galerkin approximations
combined with a contraction mapping theorem. Secondly, the exponential growth
of the energy and the $L^p$ norm of the solution is presented.
|
0810.1013v1
|
2008-11-20
|
An explanation for the pseudogap of high-temperature superconductors based on quantum optics
|
We first explain the pseudogap of high-temperature superconductivity based on
an approach of quantum optics. After introducing a damping factor for the
lifetime $\tau$ of quasiparticles, the superconducting dome is naturally
produced, and the pseudogap is the consequence of pairing with damped
coherence. We derive a new expression of Ginzburg-Landau free energy density,
in which a six-order term due to decoherence damping effect is included.
Without invoking any microscopic pairing mechanism, this approach provides a
simple universal equation of second-order phase transition, which can be
reduced to two well-known empirical scaling equations: the superconducting dome
Presland-Tallon equation, and the normal-state pseudogap crossover temperature
$T^{*}$ line.
|
0811.3262v1
|
2008-12-18
|
Exponential decay for solutions to semilinear damped wave equation
|
This paper is concerned with decay estimate of solutions to the semilinear
wave equation with strong damping in a bounded domain. Introducing an
appropriate Lyaponuv function, we prove that when the damping is linear, we can
find initial data, for which the solution decays exponentially. This result
improves an early one in an article of Gazzola and Squassina.
|
0812.3637v3
|
2009-05-27
|
Difference between penetration and damping lengths in photonic crystal mirrors
|
Different mirror geometries in two-dimensional photonic crystal slabs are
studied with fully-vectorial calculations. We compare their optical properties
and, in particular, we show that, for heterostructure mirrors, the penetration
length associated with the delay induced by distributed reflection is not
correlated to the characteristic damping length of the electromagnetic energy
distribution in the mirror. This unexpected result evidences that the usual
trade-off between short damping lengths and large penetration lengths that is
classically encountered in distributed Bragg reflectors can be overcome with
carefully designed photonic crystal structures.
|
0905.4449v2
|
2009-06-01
|
Exponential Decay Rates for the Damped Korteweg-de Vries Type Equation
|
The exponential decay rate of $L^2-$norm related to the Korteweg-de Vries
equation with localized damping posed on whole real line will be established.
In addition, by using classical arguments we determine the $H^1-$norm of the
solution associated to Korteweg-de Vries equation with damping in whole domain,
can not have a decay property for an arbitrary initial data.
|
0906.0285v2
|
2009-07-02
|
Damping and decoherence of a nanomechanical resonator due to a few two level systems
|
We consider a quantum model of a nanomechanical flexing beam resonator
interacting with a bath comprising a few damped tunneling two level systems
(TLS's). In contrast with a resonator interacting bilinearly with an ohmic free
oscillator bath (modeling clamping loss, for example), the mechanical resonator
damping is amplitude dependent, while the decoherence of quantum superpositions
of mechanical position states depends only weakly on their spatial separation.
|
0907.0431v1
|
2009-07-29
|
High performance single-error-correcting quantum codes for amplitude damping
|
We construct families of high performance quantum amplitude damping codes.
All of our codes are nonadditive and most modestly outperform the best possible
additive codes in terms of encoded dimension. One family is built from
nonlinear error-correcting codes for classical asymmetric channels, with which
we systematically construct quantum amplitude damping codes with parameters
better than any prior construction known for any block length n > 7 except
n=2^r-1. We generalize this construction to employ classical codes over GF(3)
with which we numerically obtain better performing codes up to length 14.
Because the resulting codes are of the codeword stabilized (CWS) type, easy
encoding and decoding circuits are available.
|
0907.5149v1
|
2009-10-12
|
Suppression of Landau damping via electron band gap
|
The pondermotive potential in the X-ray Raman compression can generate an
electron band gap which suppresses the Landau damping. The regime is identified
where a Langmuir wave can be driven without damping in the stimulated Raman
compression. It is shown that the partial wave breaking and the frequency
detuning due to the trapped particles would be greatly reduced.
|
0910.2196v3
|
2009-10-27
|
Rabi type oscillations in damped single 2D-quantum dot
|
We present a quantized model of harmonically confined dot atom with inherent
damping in the presence of a transverse magnetic field. The model leads to a
non hermitian Hamiltonian in real coordinate. We have analytically studied the
effects that damping has on the Rabi type oscillations of the system. The model
explains the decoherence of Rabi oscillation in a Josephson Junction.
|
0910.5184v1
|
2010-01-26
|
Effect of spin-conserving scattering on Gilbert damping in ferromagnetic semiconductors
|
The Gilbert damping in ferromagnetic semiconductors is theoretically
investigated based on the $s$-$d$ model. In contrast to the situation in
metals, all the spin-conserving scattering in ferromagnetic semiconductors
supplies an additional spin relaxation channel due to the momentum dependent
effective magnetic field of the spin-orbit coupling, thereby modifies the
Gilbert damping. In the presence of a pure spin current, we predict a new
contribution due to the interplay of the anisotropic spin-orbit coupling and a
pure spin current.
|
1001.4576v1
|
2010-03-08
|
A single-ion nonlinear mechanical oscillator
|
We study the steady state motion of a single trapped ion oscillator driven to
the nonlinear regime. Damping is achieved via Doppler laser-cooling. The ion
motion is found to be well described by the Duffing oscillator model with an
additional nonlinear damping term. We demonstrate a unique ability of tuning
both the linear as well as the nonlinear damping coefficients by controlling
the cooling laser parameters. Our observations open a way for the investigation
of nonlinear dynamics on the quantum-to-classical interface as well as
mechanical noise squeezing in laser-cooling dynamics.
|
1003.1577v1
|
2010-03-24
|
Global attractors for strongly damped wave equations with displacement dependent damping and nonlinear source term of critical exponent
|
In this paper the long time behaviour of the solutions of 3-D strongly damped
wave equation is studied. It is shown that the semigroup generated by this
equation possesses a global attractor in H_{0}^{1}(\Omega)\times L_{2}(\Omega)
and then it is proved that this global attractor is a bounded subset of
H^{2}(\Omega)\times H^{2}(\Omega) and also a global attractor in
H^{2}(\Omega)\cap H_{0}^{1}(\Omega)\times H_{0}^{1}(\Omega).
|
1003.4760v3
|
2010-04-12
|
Entanglement properties of optical coherent states under amplitude damping
|
Through concurrence, we characterize the entanglement properties of optical
coherent-state qubits subject to an amplitude damping channel. We investigate
the distillation capabilities of known error correcting codes and obtain upper
bounds on the entanglement depending on the non-orthogonality of the coherent
states and the channel damping parameter. This work provides a first, full
quantitative analysis of these photon-loss codes which are naturally
reminiscent of the standard qubit codes against Pauli errors.
|
1004.1931v2
|
2010-05-20
|
Nonclassical phase-space trajectories for the damped harmonic quantum oscillator
|
The phase-space path-integral approach to the damped harmonic oscillator is
analyzed beyond the Markovian approximation. It is found that pairs of
nonclassical trajectories contribute to the path-integral representation of the
Wigner propagating function. Due to the linearity of the problem, the sum
coordinate of a pair still satisfies the classical equation of motion.
Furthermore, it is shown that the broadening of the Wigner propagating function
of the damped oscillator arises due to the time-nonlocal interaction mediated
by the heat bath.
|
1005.3839v1
|
2010-06-09
|
Self frequency-locking of a chain of oscillators
|
The paper studies the vibrational modes of a slightly damped uniform chain,
with n masses coupled by elastic forces. It will be shown that, for certain
lengths of the chain, that is for certain values of n, the damping of one of
the masses at a specific position in the chain is able to constrain the
vibration of the system to oscillate at a specific frequency. The damped mass
turns out to be a node of the chain, subdividing it in two parts. This node can
be considered as the synchronization element of the two subchains. As a
consequence the oscillating system of n-masses is self-locking to the
synchronized frequency of its subchains.
|
1006.1722v1
|
2010-08-20
|
First principles quasiparticle damping rates in bulk lead
|
First principles calculations of the damping rates (inverse inelastic
lifetimes) of low energy quasiparticles in bulk Pb are presented. Damping rates
are obtained both for excited electrons and holes with energies up to 8 eV on a
set of k vectors throughout the Brillouin zone (BZ). Strong localization
effects in the calculated lifetimes are found. Averaged over the BZ inelastic
lifetimes versus quasiparticle energy are reported as well. In addition, the
effect of the spin-orbit induced splitting in the band structure on the
calculated lifetimes in Pb is investigated.
|
1008.3415v1
|
2010-12-07
|
Turbulence damping as a measure of the flow dimensionality
|
The dimensionality of turbulence in fluid layers determines their properties.
We study electromagnetically driven flows in finite depth fluid layers and show
that eddy viscosity, which appears as a result of three-dimensional motions,
leads to increased bottom damping. The anomaly coefficient, which characterizes
the deviation of damping from the one derived using a quasi-two-dimensional
model, can be used as a measure of the flow dimensionality. Experiments in
turbulent layers show that when the anomaly coefficient becomes high, the
turbulent inverse energy cascade is suppressed. In the opposite limit
turbulence can self-organize into a coherent flow.
|
1012.1371v1
|
2011-03-18
|
Single File Diffusion of particles with long ranged interactions: damping and finite size effects
|
We study the Single File Diffusion (SFD) of a cyclic chain of particles that
cannot cross each other, in a thermal bath, with long ranged interactions, and
arbitrary damping. We present simulations that exhibit new behaviors
specifically associated to systems of small number of particles and to small
damping. In order to understand those results, we present an original analysis
based on the decomposition of the particles motion in the normal modes of the
chain. Our model explains all dynamic regimes observed in our simulations, and
provides convincing estimates of the crossover times between those regimes.
|
1103.3642v1
|
2011-04-21
|
Spin Damping Monopole
|
We present theoretical evidence that a magnetic monopole emerges in dynamic
magnetic systems in the presence of the spin-orbit interaction. The monopole
field is expressed in terms of spin damping associated with magnetization
dynamics. We demonstrate that the observation of this spin damping monopole is
accomplished electrically using Ampere's law for monopole current. Our
discovery suggests the integration of monopoles into electronics, namely,
monopolotronics.
|
1104.4215v2
|
2011-08-16
|
Long time dynamics for forced and weakly damped KdV on the torus
|
The forced and weakly damped Korteweg-de Vries (KdV) equation with periodic
boundary conditions is considered. Starting from $L^2$ and mean-zero initial
data we prove that the solution decomposes into two parts; a linear one which
decays to zero as time goes to infinity and a nonlinear one which always
belongs to a smoother space. As a corollary we prove that all solutions are
attracted by a ball in $H^s$, $s\in(0,1)$, whose radius depends only on $s$,
the $L^2$ norm of the forcing term and the damping parameter. This gives a new
proof for the existence of a smooth global attractor and provides quantitative
information on the size of the attractor set in $H^s$.
|
1108.3358v1
|
2011-10-17
|
Normal Mode Expansion of Damped Coupled Oscillators in 3 dimensions
|
In this paper, I aim to study free oscillations of a system of oscillators in
more than one dimensions in the absence of damping. The basic approach lies in
decoupling the motion in the individual perpendicular directions. Once the
equations are decoupled, the existent techniques of Normal mode expansion for
1-dimensional oscillators are used to solve for the equations of motion. I also
study the motion of a driven system of oscillators in higher dimensions in the
presence of a velocity dependent damping force.
|
1110.3773v1
|
2011-10-25
|
Distinguishing mesoscopic quantum superpositions from statistical mixtures in periodically shaken double wells
|
For Bose-Einstein condensates in double wells, N-particle Rabi-like
oscillations often seem to be damped. Far from being a decoherence effect, the
apparent damping can indicate the emergence of quantum superpositions in the
many-particle quantum dynamics. However, in an experiment it would be difficult
to distinguish the apparent damping from decoherence effects. The present paper
suggests using controlled periodic shaking to quasi-instantaneously switch the
sign of an effective Hamiltonian, thus implementing an `echo' technique which
distinguishes quantum superpositions from statistical mixtures. The scheme for
the effective time-reversal is tested by numerically solving the time-dependent
N-particle Schrodinger equation.
|
1110.5444v1
|
2011-11-04
|
Tunable magnetization relaxation in spin valves
|
In spin values the damping parameters of the free layer are determined
non-locally by the entire magnetic configuration. In a dual spin valve
structure that comprises a free layer embedded between two pinned layers, the
spin pumping mechanism, in combination with the angular momentum conservation,
renders the tensor-like damping parameters tunable by varying the interfacial
and diffusive properties. Simulations based on the Landau-Lifshitz-Gilbert
phenomenology for a macrospin model are performed with the tensor-like damping
and the relaxation time of the free layer magnetization is found to be largely
dependent on while tunable through the magnetic configuration of the
source-drain magnetization.
|
1111.1219v1
|
2011-11-23
|
Wave Propagation And Landau-Type Damping In Liquids
|
Intermolecular forces are modeled by means of a modified Lennard-Jones
potential, introducing a distance of minimum approach, and the effect of
intermolecular interactions is accounted for with a self consistent field of
the Vlasov type. A Vlasov equation is then written and used to investigate the
propagation of perturbations in a liquid. A dispersion relation is obtained and
an effect of damping, analogous to what is known in plasmas as "Landau
damping", is found to take place.
|
1111.5519v3
|
2011-11-25
|
Radiation Damping for Speeding-up NMR Applications
|
We demonstrate theoretically and numerically how to control the NMR
relaxation rate after application of the standard spin echo technique. Using
radiation damping, we return the nuclear magnetization to its equilibrium state
during a time interval that is negligible compared to the relaxation time. We
obtain an estimate for optimal radiation damping which is consistent with our
numerical simulations.
|
1111.7060v1
|
2011-12-09
|
Perturbed damped pendulum: finding periodic solutions
|
Using the damped pendulum system we introduce the averaging method to study
the periodic solutions of a dynamical system with small perturbation. We
provide sufficient conditions for the existence of periodic solutions with
small amplitude of the non--linear perturbed damped pendulum. The averaging
theory provides a useful means to study dynamical systems, accessible to Master
and PhD students.
|
1112.2129v2
|
2011-12-28
|
The role of damping for the driven anharmonic quantum oscillator
|
For the model of a linearly driven quantum anharmonic oscillator, the role of
damping is investigated. We compare the position of the stable points in phase
space obtained from a classical analysis to the result of a quantum mechanical
analysis. The solution of the full master equation shows that the stable points
behave qualitatively similar to the classical solution but with small
modifications. Both the quantum effects and additional effects of temperature
can be described by renormalizing the damping.
|
1112.6119v1
|
2012-01-03
|
Creating and studying ion acoustic waves in ultracold neutral plasmas
|
We excite ion acoustic waves in ultracold neutral plasmas by imprinting
density modulations during plasma creation. Laser-induced fluorescence is used
to observe the density and velocity perturbations created by the waves. The
effect of expansion of the plasma on the evolution of the wave amplitude is
described by treating the wave action as an adiabatic invariant. After
accounting for this effect, we determine that the waves are weakly damped, but
the damping is significantly faster than expected for Landau damping.
|
1201.0786v1
|
2012-01-05
|
Damped bead on a rotating circular hoop - a bifurcation zoo
|
The evergreen problem of a bead on a rotating hoop shows a multitude of
bifurcations when the bead moves with friction. This motion is studied for
different values of the damping coefficient and rotational speeds of the hoop.
Phase portraits and trajectories corresponding to all different modes of motion
of the bead are presented. They illustrate the rich dynamics associated with
this simple system. For some range of values of the damping coefficient and
rotational speeds of the hoop, linear stability analysis of the equilibrium
points is inadequate to classify their nature. A technique involving
transformation of coordinates and order of magnitude arguments is presented to
examine such cases. This may provide a general framework to investigate other
complex systems.
|
1201.1218v1
|
2012-02-24
|
Small data global existence for the semilinear wave equation with space-time dependent damping
|
In this paper we consider the critical exponent problem for the semilinear
wave equation with space-time dependent damping. When the damping is effective,
it is expected that the critical exponent agrees with that of only space
dependent coefficient case. We shall prove that there exists a unique global
solution for small data if the power of nonlinearity is larger than the
expected exponent. Moreover, we do not assume that the data are compactly
supported. However, it is still open whether there exists a blow-up solution if
the power of nonlinearity is smaller than the expected exponent.
|
1202.5379v1
|
2012-03-11
|
Magnetic damping of a carbon nanotube NEMS resonator
|
A suspended, doubly clamped single wall carbon nanotube is characterized at
cryogenic temperatures. We observe specific switching effects in dc-current
spectroscopy of the embedded quantum dot. These have been identified previously
as nano-electromechanical self-excitation of the system, where positive
feedback from single electron tunneling drives mechanical motion. A magnetic
field suppresses this effect, by providing an additional damping mechanism.
This is modeled by eddy current damping, and confirmed by measuring the
resonance quality factor of the rf-driven nano-electromechanical resonator in
an increasing magnetic field.
|
1203.2319v2
|
2012-04-02
|
Random Symmetry Breaking and Freezing in Chaotic Networks
|
Parameter space of a driven damped oscillator in a double well potential
presents either a chaotic trajectory with sign oscillating amplitude or a
non-chaotic trajectory with a fixed sign amplitude. A network of such delay
coupled damped oscillators is shown to present chaotic dynamics while the
amplitude sign of each damped oscillator is randomly frozen. This phenomenon of
random broken global symmetry of the network simultaneously with random
freezing of each degree of freedom is accompanied by the existence of
exponentially many randomly frozen chaotic attractors with the ize of the
network. Results are exemplified by a network of modified Duffing oscillators
with infinite ange pseudo-inverse delayed interactions.
|
1204.0528v1
|
2012-04-04
|
Nonlinear Damping in Graphene Resonators
|
Based on a continuum mechanical model for single-layer graphene we propose
and analyze a microscopic mechanism for dissipation in nanoelectromechanical
graphene resonators. We find that coupling between flexural modes and in-plane
phonons leads to linear and nonlinear damping of out-of-plane vibrations. By
tuning external parameters such as bias and ac voltages, one can cross over
from a linear to a nonlinear-damping dominated regime. We discuss the behavior
of the effective quality factor in this context.
|
1204.0911v2
|
2012-05-22
|
Heavy quark damping rate in hot viscous QCD plasma
|
We derive an expression for the heavy quark damping rate in hot quark gluon
plasma in presence of flow. Here all the bath particles here are out of
equilibrium due to the existence of non-zero velocity gradient. The magnetic
sector shows similar infrared divergences even after hard thermal loop
corrections as one encounters in case of non-viscous plasma. We estimate the
first order correction in ($\eta/s$) for heavy quark damping rate due to the
non-zero viscosity of the QCD plasma.
|
1205.4895v3
|
2012-05-25
|
Spin wave amplification driven by heat flow: the role of damping and exchange interaction
|
In this article we report on micromagnetic simulations performed on a
permalloy nanostructure in presence of a uniform thermal gradient. Our
numerical simulations show that heat flow is an effective mean to compensate
the damping, and that the gradients at which spin-wave amplification is
observed are experimentally accessible. In particular, we have studied the role
of the Gilbert damping parameter on spin-wave amplification.
|
1205.5650v2
|
2012-07-24
|
Quantum capacity of an amplitude-damping channel with memory
|
We calculate the quantum capacity of an amplitude-damping channel with time
correlated Markov noise, for two channel uses. Our results show that memory of
the channel increases it's ability to transmit quantum information
significantly. We analyze and compare our findings with earlier numerical
results on amplitude-damping channel with memory. An upper bound on the amount
of quantum information transmitted over the channel in presence of memory, for
an arbitrary number of channel uses is also presented.
|
1207.5612v3
|
2012-08-21
|
Protecting quantum entanglement from amplitude damping
|
Quantum entanglement is a critical resource for quantum information and
quantum computation. However, entanglement of a quantum system is subjected to
change due to the interaction with the environment. One typical result of the
interaction is the amplitude damping that usually results in the reduction of
the entanglement. Here we propose a protocol to protect quantum entanglement
from the amplitude damping by applying Hadamard and CNOT gates. As opposed to
some recently studied methods, the scheme presented here does not require weak
measurement in the reversal process, leading to a faster recovery of
entanglement. We propose a possible experimental implementation based on linear
optical system.
|
1208.4187v2
|
2012-10-03
|
Exact solutions for discrete breathers in forced-damped chain
|
Exact solutions for symmetric discrete breathers (DBs) are obtained in
forced-damped linear chain with on-site vibro-impact constraints. The damping
is related to inelastic impacts; the forcing may be chosen from broad class of
periodic antisymmetric functions. Global conditions for existence and stability
of the DB are established. Some unusual phenomena, like non-monotonous
dependence of the stability boundary on the forcing amplitude, are revealed
analytically for the full system and illustrated numerically for small periodic
lattices.
|
1210.1085v1
|
2012-12-20
|
How long-range interactions tune the damping in compact stars
|
Long-range interactions lead to non-Fermi liquid effects in dense matter. We
show that, in contrast to other material properties, their effect on the bulk
viscosity of quark matter is significant since they shift its resonant maximum
and can thereby change the viscosity by many orders of magnitude. This is of
importance for the damping of oscillations of compact stars, like in particular
unstable r-modes, and the quest to detect signatures of deconfined matter in
astrophysical observations. We find that, in contrast to neutron stars with
standard damping mechanisms, compact stars that contain ungapped quark matter
are consistent with the observed data on low mass x-ray binaries.
|
1212.5242v1
|
2013-02-12
|
Impact of gluon damping on heavy-quark quenching
|
In this conference contribution, we discuss the influence of
gluon-bremsstrahlung damping in hot, absorptive QCD matter on the heavy-quark
radiation spectra. Within our Monte-Carlo implementation for the description of
the heavy-quark in-medium propagation we demonstrate that as a consequence of
gluon damping the quenching of heavy quarks becomes significantly affected at
higher transverse momenta.
|
1302.2934v1
|
2013-03-12
|
On nonlinear Schrodinger type equations with nonlinear damping
|
We consider equations of nonlinear Schrodinger type augmented by nonlinear
damping terms. We show that nonlinear damping prevents finite time blow-up in
several situations, which we describe. We also prove that the presence of a
quadratic confinement in all spatial directions drives the solution of our
model to zero for large time. In the case without external potential we prove
that the solution may not go to zero for large time due to (non-trivial)
scattering.
|
1303.3033v2
|
2013-06-15
|
A formula for damping interarea oscillations with generator redispatch
|
We derive a new formula for the sensitivity of electromechanical oscillation
damping with respect to generator redispatch. The formula could lead to some
combination of observations, computations and heuristics to more effectively
damp interarea oscillations.
|
1306.3590v2
|
2013-07-24
|
Eigenvalue asymptotics for the damped wave equation on metric graphs
|
We consider the linear damped wave equation on finite metric graphs and
analyse its spectral properties with an emphasis on the asymptotic behaviour of
eigenvalues. In the case of equilateral graphs and standard coupling conditions
we show that there is only a finite number of high-frequency abscissas, whose
location is solely determined by the averages of the damping terms on each
edge. We further describe some of the possible behaviour when the edge lengths
are no longer necessarily equal but remain commensurate.
|
1307.6377v3
|
2013-08-03
|
Hadamard well-posedness for a hyperbolic equation of viscoelasticity with supercritical sources and damping
|
Presented here is a study of a viscoelastic wave equation with supercritical
source and damping terms. We employ the theory of monotone operators and
nonlinear semigroups, combined with energy methods to establish the existence
of a unique local weak solution. In addition, it is shown that the solution
depends continuously on the initial data and is global provided the damping
dominates the source in an appropriate sense.
|
1308.0720v2
|
2013-10-14
|
Signatures of two-level defects in the temperature-dependent damping of nanomechanical silicon nitride resonators
|
The damping rates of high quality factor nanomechanical resonators are well
beyond intrinsic limits. Here, we explore the underlying microscopic loss
mechanisms by investigating the temperature-dependent damping of the
fundamental and third harmonic transverse flexural mode of a doubly clamped
silicon nitride string. It exhibits characteristic maxima reminiscent of
two-level defects typical for amorphous materials. Coupling to those defects
relaxes the momentum selection rules, allowing energy transfer from discrete
long wavelength resonator modes to the high frequency phonon environment.
|
1310.3671v1
|
2013-10-25
|
Quenched decoherence in qubit dynamics due to strong amplitude-damping noise
|
We study non-perturbatively the time evolution of a qubit subject to
amplitude-damping noise. We show that at strong coupling the qubit decoherence
can be quenched owing to large environment feedbacks, such that the qubit can
evolve coherently even in the long-time limit. As an application, we show that
for a quantum channel that consists of two independent qubits subject to
uncorrelated local amplitude-damping noises, it can maintain at strong coupling
finite entanglement and better than classical teleportation fidelity at long
times.
|
1310.6843v2
|
2013-11-16
|
Shear viscosity due to the Landau damping from quark-pion interaction
|
We have calculated the shear viscosity coefficient $\eta$ of the strongly
interacting matter in the relaxation time approximation, where a quasi particle
description of quarks with its dynamical mass is considered from NJL model. Due
to the thermodynamic scattering of quarks with pseudo scalar type condensate
(i.e. pion), a non zero Landau damping will be acquired by the propagating
quarks. This Landau damping may be obtained from the Landau cut contribution of
the in-medium self-energy of quark-pion loop, which is evaluated in the
framework of real-time thermal field theory.
|
1311.4070v1
|
2013-12-19
|
Cyclotron dynamics of interacting bosons in artificial magnetic fields
|
We study theoretically quantum dynamics of interacting bosons in artificial
magnetic fields as engineered in recent ultracold atomic experiments, where
quantum cyclotron orbital motion has been observed. With exact numerical
simulations and perturbative analyses, we find that interactions induce damping
in the cyclotron motion. The damping time is found to be dependent on
interaction and tunneling strengths monotonically, while its dependence on
magnetic flux is non-monotonic. Sufficiently strong interactions would render
bosons dynamically localized inhibiting the cyclotron motion. The damping
predicted by us can be construed as an interaction-induced quantum decoherence
of the cyclotron motion.
|
1312.5747v2
|
2014-01-11
|
Damping in two component Bose gas
|
We investigate the Landau and Baliaev damping of the collective modes in a
two-component Bose gas using the mean-field approximation. We show that due to
the two body atom-atom interaction, oscillations of each component is coupled
to the thermal excitations of the other component which gives rise to creation
or destruction of the elementary excitations that can take place in the two
separate components.In addition we find that the damping is also enhanced due
to inter-component coupling.
|
1401.2537v1
|
2014-03-24
|
Existence Results for Some Damped Second-Order Volterra Integro-Differential Equations
|
In this paper we make a subtle use of operator theory techniques and the
well-known Schauder fixed-point principle to establish the existence of
pseudo-almost automorphic solutions to some second-order damped
integro-differential equations with pseudo-almost automorphic coefficients. In
order to illustrate our main results, we will study the existence of
pseudo-almost automorphic solutions to a structurally damped plate-like
boundary value problem.
|
1403.5955v1
|
2014-04-25
|
The time singular limit for a fourth-order damped wave equation for MEMS
|
We consider a free boundary problem modeling electrostatic
microelectromechanical systems. The model consists of a fourth-order damped
wave equation for the elastic plate displacement which is coupled to an
elliptic equation for the electrostatic potential. We first review some recent
results on existence and non-existence of steady-states as well as on local and
global well-posedness of the dynamical problem, the main focus being on the
possible touchdown behavior of the elastic plate. We then investigate the
behavior of the solutions in the time singular limit when the ratio between
inertial and damping effects tends to zero.
|
1404.6342v1
|
2014-05-12
|
A note on a strongly damped wave equation with fast growing nonlinearities
|
A strongly damped wave equation including the displacement depending
nonlinear damping term and nonlinear interaction function is considered. The
main aim of the note is to show that under the standard dissipativity
restrictions on the nonlinearities involved the initial boundary value problem
for the considered equation is globally well-posed in the class of sufficiently
regular solutions and the semigroup generated by the problem possesses a global
attractor in the corresponding phase space. These results are obtained for the
nonlinearities of an arbitrary polynomial growth and without the assumption
that the considered problem has a global Lyapunov function.
|
1405.2707v1
|
2014-06-03
|
Optimal Estimation of a Classical Force with a Damped Oscillator in the non-Markovian Bath
|
We solve the optimal quantum limit of probing a classical force exactly by a
damped oscillator initially prepared in the factorized squeezed state. The
memory effects of the thermal bath on the oscillator evolution are
investigated. We show that the optimal force sensitivity obtained by the
quantum estimation theory approaches to zero for the non-Markovian bath,
whereas approaches to a finite non-zero value for the Markovian bath as the
energy of the damped oscillator goes to infinity.
|
1406.0658v1
|
2014-08-09
|
Local existence results for the Westervelt equation with nonlinear damping and Neumann as well as absorbing boundary conditions
|
We investigate the Westervelt equation with several versions of nonlinear
damping and lower order damping terms and Neumann as well as absorbing boundary
conditions. We prove local in time existence of weak solutions under the
assumption that the initial and boundary data are sufficiently small.
Additionally, we prove local well-posedness in the case of spatially varying
$L^{\infty}$ coefficients, a model relevant in high intensity focused
ultrasound (HIFU) applications.
|
1408.2160v1
|
2014-08-11
|
Characterization and suppression techniques for degree of radiation damping in inversion recovery measurements
|
Radiation damping (RD) has been shown to affect T1 measurement in inversion
recovery experiments. In this work, we demonstrate that the extent of RD
depends upon the T1 of the sample. RD difference spectroscopy (RADDSY) is used
to characterize the severity of RD, while gradient inversion recovery (GIR) is
used for RD suppression in T1 measurements. At 9.4 T, for the radiation damping
characteristic time (Trd) of 50 ms, these investigations show non-negligible RD
effects for T1 values greater than Trd, with severe distortions for T1 longer
than about 150 ms, showing reasonable agreement with the predicted Trd. We also
report a discrepancy between published expressions for the characteristic RD
time.
|
1408.2457v2
|
2014-09-28
|
Spin-electron acoustic waves: The Landau damping and ion contribution in the spectrum
|
Separated spin-up and spin-down quantum kinetics is derived for more detailed
research of the spin-electron acoustic waves. Kinetic theory allows to obtain
spectrum of the spin-electron acoustic waves including effects of occupation of
quantum states more accurately than quantum hydrodynamics. We apply quantum
kinetic to calculate the Landau damping of the spin-electron acoustic waves. We
have considered contribution of ions dynamics in the spin-electron acoustic
wave spectrum. We obtain contribution of ions in the Landau damping in
temperature regime of classic ions. Kinetic analysis for ion-acoustic, zero
sound, and Langmuir waves at separated spin-up and spin-down electron dynamics
is presented as well.
|
1409.7885v1
|
2014-10-15
|
Quasiparticle Damping of Surface Waves in Superfluid $^3$He and $^4$He
|
Oscillations on free surface of superfluids at the inviscid limit are damped
by quasiparticle scattering. We have studied this effect in both superfluids
$^3$He and $^4$He deep below the respective critical temperatures. Surface
oscillators offer several benefits over immersed mechanical oscillators
traditionally used for similar purposes. Damping is modeled as specular
scattering of ballistic quasiparticles from the moving free surface. The model
is in reasonable agreement with our measurements for superfluid $^4$He but
significant deviation is found for $^3$He.
|
1410.4071v1
|
2014-12-22
|
Long time behavior for a semilinear hyperbolic equation with asymtotically vanishing damping term and convex potential
|
We investigate the asymptotic behavior, as t goes to infinity, for a
semilinear hyperbolic equation with asymptotically smal dissipation and convex
potential. We prove that if the damping term behaves like K/t^\alpha for t
large enough, k>0 and 0</alpha<1 then every global solution converges weakly to
an equilibrium point. This result is a positive answer to a question left open
in the paper [A. Cabot and P. Frankel, Asymptotics for some semilinear
hyperbolic equation with non-autonomous damping. J. Differential Equations 252
(2012) 294-322.]
|
1412.7008v1
|
2015-02-06
|
Microscopic theory of Gilbert damping in metallic ferromagnets
|
We present a microscopic theory for magnetization relaxation in metallic
ferromagnets of nanoscopic dimensions that is based on the dynamic spin
response matrix in the presence of spin-orbit coupling. Our approach allows the
calculation of the spin excitation damping rate even for perfectly crystalline
systems, where existing microscopic approaches fail. We demonstrate that the
relaxation properties are not completely determined by the transverse
susceptibility alone, and that the damping rate has a non-negligible frequency
dependence in experimentally relevant situations. Our results indicate that the
standard Landau-Lifshitz-Gilbert phenomenology is not always appropriate to
describe spin dynamics of metallic nanostructure in the presence of strong
spin-orbit coupling.
|
1502.02068v1
|
2015-03-03
|
Large Deviations for the Langevin equation with strong damping
|
We study large deviations in the Langevin dynamics, with damping of order
$\e^{-1}$ and noise of order $1$, as $\e\downarrow 0$. The damping coefficient
is assumed to be state dependent. We proceed first with a change of time and
then, we use a weak convergence approach to large deviations and their
equivalent formulation in terms of the Laplace principle, to determine the good
action functional.
Some applications of these results to the exit problem from a domain and to
the wave front propagation for a suitable class of reaction diffusion equations
are considered.
|
1503.01027v1
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Subsets and Splits
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