publicationDate stringlengths 1 2.79k | title stringlengths 1 36.5k ⌀ | abstract stringlengths 1 37.3k ⌀ | id stringlengths 9 47 |
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2023-10-30 | Beliaev damping in Bose gas | According to the Bogoliubov theory the low energy behaviour of the Bose gas
at zero temperature can be described by non-interacting bosonic quasiparticles
called phonons. In this work the damping rate of phonons at low momenta, the
so-called Beliaev damping, is explained and computed with simple arguments
involving the Fermi Golden Rule and Bogoliubov's quasiparticles. | 2310.20070v1 |
2023-11-25 | Energy scattering for the unsteady damped nonlinear Schrodinger equation | We investigate the large time behavior of the solutions to the nonlinear
focusing Schr\"odinger equation with a time-dependent damping in the energy
sub-critical regime. Under non classical assumptions on the unsteady damping
term, we prove some scattering results in the energy space. | 2311.14980v2 |
2017-10-18 | Direct detection of metal-insulator phase transitions using the modified Backus-Gilbert method | The detection of the (semi)metal-insulator phase transition can be extremely
difficult if the local order parameter which characterizes the ordered phase is
unknown.In some cases, it is even impossible to define a local order parameter:
the most prominent example of such system is the spin liquid state. This state
was proposed to exist in theHubbard model on the hexagonal lattice in a region
between the semimetal phase and the antiferromagnetic insulator phase. The
existence of this phase has been the subject of a long debate. In order to
detect these exotic phases we must use alternative methods to those used for
more familiar examples of spontaneous symmetry breaking. We have modified the
Backus-Gilbert method of analytic continuation which was previously used in the
calculation of the pion quasiparticle mass in lattice QCD. The modification of
the method consists of the introduction of the Tikhonov regularization scheme
which was used to treat the ill-conditioned kernel. This modified
Backus-Gilbert method is applied to the Euclidean propagators in momentum space
calculated using the hybridMonte Carlo algorithm. In this way, it is possible
to reconstruct the full dispersion relation and to estimate the mass gap, which
is a direct signal of the transition to the insulating state. We demonstrate
the utility of this method in our calculations for the Hubbard model on the
hexagonal lattice. We also apply the method to the metal-insulator phase
transition in the Hubbard-Coulomb model on the square lattice. | 1710.06675v1 |
2020-09-14 | Bounds and Code Constructions for Partially Defect Memory Cells | This paper considers coding for so-called partially stuck memory cells. Such
memory cells can only store partial information as some of their levels cannot
be used due to, e.g., wear out. First, we present a new code construction for
masking such partially stuck cells while additionally correcting errors. This
construction (for cells with $q >2$ levels) is achieved by generalizing an
existing masking-only construction in [1] (based on binary codes) to correct
errors as well. Compared to previous constructions in [2], our new construction
achieves larger rates for many sets of parameters. Second, we derive a
sphere-packing (any number of $u$ partially stuck cells) and a
Gilbert-Varshamov bound ($u<q$ partially stuck cells) for codes that can mask a
certain number of partially stuck cells and correct errors additionally. A
numerical comparison between the new bounds and our previous construction of
PSMCs for the case $u<q$ in [2] shows that our construction lies above the
Gilbert-Varshamov-like bound for several code parameters. | 2009.06512v3 |
2002-02-21 | Mechanisms of spin-polarized current-driven magnetization switching | The mechanisms of the magnetization switching of magnetic multilayers driven
by a current are studied by including exchange interaction between local
moments and spin accumulation of conduction electrons. It is found that this
exchange interaction leads to two additional terms in the
Landau-Lifshitz-Gilbert equation: an effective field and a spin torque. Both
terms are proportional to the transverse spin accumulation and have comparable
magnitudes. | 0202363v1 |
2005-10-30 | Domain instability during precessional magnetization reversal | Spin wave equations in the non-equilibrium precessing state of a
ferromagnetic system are found. They show a spin-wave instability towards
growing domains of stable magnetization. Precession of the uniform
magnetization mode is described by the Landau Lifshitz equation with the
exponentially growing in time effective Gilbert dissipation constant that could
have both signs. On the developed stages of the domain instability a
non-stationary picture of domain chaos is observed. | 0510817v1 |
1991-12-02 | Perturbations of a Stringy Black Hole | We extend the three dimensional stringy black hole of Horne and Horowitz to
four dimensions. After a brief discussion of the global properties of the
metric, we discuss the stability of the background with respect to small
perturbations, following the methods of Gilbert and of Chandrasekhar. The
potential for axial perturbations is found to be positive definite. | 9112001v2 |
1996-05-06 | Finitely presented subgroups of automatic groups and their isoperimetric functions | We describe a general technique for embedding certain amalgamated products
into direct products. This technique provides us with a way of constructing a
host of finitely presented subgroups of automatic groups which are not even
asynchronously automatic. We can also arrange that such subgroups satisfy, at
best, an exponential isoperimetric inequality. | 9605201v1 |
1999-07-22 | Constructing Hyperbolic Manifolds | In this paper we show how to obtain representations of Coxeter groups acting
on H^n to certain classical groups. We determine when the kernel of such a
representation is torsion-free and thus the quotient a hyperbolic n-manifold. | 9907139v1 |
2002-02-06 | Quaternionic equation for electromagnetic fields in inhomogeneous media | We show that the Maxwell equations for arbitrary inhomogeneous media are
equivalent to a single quaternionic equation which can be considered as a
generalization of the Vekua equation for generalized analytic functions. | 0202010v1 |
1996-02-29 | Error Correction in Quantum Communication | We show how procedures which can correct phase and amplitude errors can be
directly applied to correct errors due to quantum entanglement. We specify
general criteria for quantum error correction, introduce quantum versions of
the Hamming and the Gilbert-Varshamov bounds and comment on the practical
implementation of quantum codes. | 9602022v1 |
2007-05-19 | Log-periodic drift oscillations in self-similar billiards | We study a particle moving at unit speed in a self-similar Lorentz billiard
channel; the latter consists of an infinite sequence of cells which are
identical in shape but growing exponentially in size, from left to right. We
present numerical computation of the drift term in this system and establish
the logarithmic periodicity of the corrections to the average drift. | 0705.2790v1 |
2008-04-26 | Asymptotic Bound on Binary Self-Orthogonal Codes | We present two constructions for binary self-orthogonal codes. It turns out
that our constructions yield a constructive bound on binary self-orthogonal
codes. In particular, when the information rate R=1/2, by our constructive
lower bound, the relative minimum distance \delta\approx 0.0595 (for GV bound,
\delta\approx 0.110). Moreover, we have proved that the binary self-orthogonal
codes asymptotically achieve the Gilbert-Varshamov bound. | 0804.4194v1 |
2008-11-14 | Scott and Swarup's regular neighbourhood as a tree of cylinders | Let G be a finitely presented group. Scott and Swarup have constructed a
canonical splitting of G which encloses all almost invariant sets over
virtually polycyclic subgroups of a given length. We give an alternative
construction of this regular neighbourhood, by showing that it is the tree of
cylinders of a JSJ splitting. | 0811.2389v1 |
2009-05-04 | Self-organized quantum transitions in a spin-electron coupled system | We investigate quantum dynamics of the excited electronic states in the
double-exchange model at half-filling by solving coupled equations for the
quantum evolution of electrons and Landau-Lifshits-Gilbert equation for
classical spins. The non-adiabatic quantum transitions driving the relaxation
are coordinated through the self-organized space-time structure of the
electron/spin dynamics leading to a resonant precession analogous to the ESR
process. | 0905.0311v1 |
2009-05-04 | Oscillating Ponomarenko dynamo in the highly conducting limit | This paper considers dynamo action in smooth helical flows in cylindrical
geometry, otherwise known as Ponomarenko dynamos, with periodic time
dependence. An asymptotic framework is developed that gives growth rates and
frequencies in the highly conducting limit of large magnetic Reynolds number,
when modes tend to be localized on resonant stream surfaces. This theory is
validated by means of numerical simulations. | 0905.0415v1 |
2009-07-15 | Barnett Effect in Thin Magnetic Films and Nanostructures | The Barnett effect refers to the magnetization induced by rotation of a
demagnetized ferromagnet. We describe the location and stability of stationary
states in rotating nanostructures using the Landau-Lifshitz-Gilbert equation.
The conditions for an experimental observation of the Barnett effect in
different materials and sample geometries are discussed. | 0907.2648v1 |
2009-12-24 | Scenarios of Gravitino Dark Matter and their Cosmological and Particle Physics Implications | I report on some scenarios where the gravitino is the dark matter and the
supersymmetry breaking mediated by a gauge sector. | 0912.4885v1 |
2010-07-20 | Factoring Permutation Matrices Into a Product of Tridiagonal Matrices | Gilbert Strang posited that a permutation matrix of bandwidth $w$ can be
written as a product of $N < 2w$ permutation matrices of bandwidth 1. A proof
employing a greedy ``parallel bubblesort'' algorithm on the rows of the
permutation matrix is detailed and further points of interest are elaborated. | 1007.3467v1 |
2011-05-26 | Qu'est-ce qu'une espèce de structures? Genèse et description | This is an overview (in french) of the Theory of Species for a general
audience. Basic notions are introduced in a non too technical manner, with an
explanation of why should one approach the notion of discrete structures in
this particular way. | 1105.5406v1 |
2011-12-16 | Reply to the comment of T.Gilbert and D.P.Sanders on "Capturing correlations in chaotic diffusion by approximation methods" | This is a reply to the comment by Gilbert and Sanders [arXiv:1111.6271
(2011)]. We point out that their comment is a follow-up of a previous
discussion which we briefly summarize before we refute their new criticism. | 1112.3927v1 |
2012-03-24 | A new look at finitely generated metabelian groups | A group is metabelian if its commutator subgroup is abelian. For finitely
generated metabelian groups, classical commutative algebra, algebraic geometry
and geometric group theory, especially the latter two subjects, can be brought
to bear on their study. The object of this paper is to describe some of the new
ideas and open problems that arise. | 1203.5431v1 |
2012-06-05 | A convergent and precise finite element scheme for Landau-Lifschitz-Gilbert equation | In this paper, we rigorously study an order 2 scheme that was previously
proposed by some of the authors. A slight modification is proposed that enables
us to prove the convergence of the scheme while simplifying in the same time
the inner iteration. | 1206.0997v1 |
2013-01-20 | Residual properties of groups defined by basic commutators | In this paper we study the residual nilpotence of groups defined by basic
commutators. We prove that the so-called Hydra groups as well as certain of
their generalizations and quotients are, in the main, residually torsion-free
nilpotent. By way of contrast we give an example of a group defined by two
basic commutators which is not residually torsion-free nilpotent. | 1301.4629v2 |
2013-03-21 | Anisimov's Theorem for inverse semigroups | The idempotent problem of a finitely generated inverse semigroup is the
formal language of all words over the generators representing idempotent
elements. This note proves that a finitely generated inverse semigroup with
regular idempotent problem is necessarily finite. This answers a question of
Gilbert and Noonan Heale, and establishes a generalisation to inverse
semigroups of Anisimov's Theorem for groups. | 1303.5239v1 |
2013-10-13 | Underwater Gas Expansion and Deflagration | The underwater combustion of a propane-air mixture in an acrylic cylinder is
captured on video from multiple angles. This experiment is designed to provide
visual data and pressure time-histories for future CFD validation studies. | 1310.3523v1 |
2014-03-12 | A semi-discrete scheme for the stochastic Landau-Lifshitz equation | We propose a new convergent time semi-discrete scheme for the stochastic
Landau-Lifshitz-Gilbert equation. The scheme is only linearly implicit and does
not require the resolution of a nonlinear problem at each time step. Using a
martingale approach, we prove the convergence in law of the scheme up to a
subsequence. | 1403.3016v1 |
2014-03-17 | Quantum codes from affine variety codes and their subfield-subcodes | We use affine variety codes and their subfield-subcodes for obtaining quantum
stabilizer codes via the CSS code construction. With this procedure, we get
codes with good parameters and a code whose parameters exceed the CSS quantum
Gilbert-Varshamov bound given by Feng and Ma. | 1403.4060v2 |
2015-10-19 | Decomposability of Finitely Generated Torsion-free Nilpotent Groups | We describe an algorithm for deciding whether or not a given finitely
generated torsion-free nilpotent group is decomposable as the direct product of
nontrivial subgroups. | 1510.05632v2 |
2016-02-27 | On automatic subsets of the Gaussian integers | Suppose that $a$ and $b$ are multiplicatively independent Gaussian integers,
that are both of modulus~$\geq \sqrt 5$. We prove that there exist a $X\subset
\mathbb Z[i]$ which is $a$-automatic but not $b$-automatic. This settles a
problem of Allouche, Cateland, Gilbert, Peitgen, Shallit, and Skordev. | 1602.08579v3 |
2016-03-02 | On self-dual double circulant codes | Self-dual double circulant codes of odd dimension are shown to be dihedral in
even characteristic and consta-dihedral in odd characteristic. Exact counting
formulae are derived for them and used to show they contain families of codes
with relative distance satisfying a modified Gilbert-Varshamov bound. | 1603.00762v1 |
2016-09-22 | Manipulation of magnetic Skyrmions with a Scanning Tunneling Microscope | The dynamics of a single magnetic Skyrmion in an atomic spin system under the
influence of Scanning Tunneling Microscope is investigated by computer
simulations solving the Landau-Lifshitz-Gilbert equation. Two possible
scenarios are described: manipulation with aid of a spin-polarized tunneling
current and by an electric field created by the scanning tunneling microscope.
The dynamics during the creation and annihilation process is studied and the
possibility to move single Skyrmions is showed. | 1609.06797v1 |
2016-11-03 | Quantile Reinforcement Learning | In reinforcement learning, the standard criterion to evaluate policies in a
state is the expectation of (discounted) sum of rewards. However, this
criterion may not always be suitable, we consider an alternative criterion
based on the notion of quantiles. In the case of episodic reinforcement
learning problems, we propose an algorithm based on stochastic approximation
with two timescales. We evaluate our proposition on a simple model of the TV
show, Who wants to be a millionaire. | 1611.00862v1 |
2017-01-30 | Elementary equivalence vs commensurability for hyperbolic groups | We study to what extent torsion-free (Gromov)-hyperbolic groups are
elementarily equivalent to their finite index subgroups. In particular, we
prove that a hyperbolic limit group either is a free product of cyclic groups
and surface groups, or admits infinitely many subgroups of finite index which
are pairwise non elementarily equivalent. | 1701.08853v1 |
2017-08-01 | Imaging from the Inside Out: Inverse Scattering with Photoactivated Internal Sources | We propose a method to reconstruct the optical properties of a scattering
medium with subwavelength resolution. The method is based on the solution to
the inverse scattering problem with photoactivated internal sources. Numerical
simulations of three-dimensional structures demonstrate that a resolution of
approximately $\lambda/25$ is achievable. | 1708.00128v1 |
2017-09-22 | On self-dual four circulant codes | Four circulant codes form a special class of $2$-generator, index $4$,
quasi-cyclic codes. Under some conditions on their generator matrices they can
be shown to be self-dual. Artin primitive root conjecture shows the existence
of an infinite subclass of these codes satisfying a modified Gilbert-Varshamov
bound. | 1709.07548v1 |
2018-02-21 | Enhanced global signal of neutral hydrogen due to excess radiation at cosmic dawn | We revisit the global 21cm signal calculation incorporating a possible radio
background at early times, and find that the global 21cm signal shows a much
stronger absorption feature, which could enhance detection prospects for future
21 cm experiments. In light of recent reports of a possible low-frequency
excess radio background, we propose that detailed 21 cm calculations should
include a possible early radio background. | 1802.07432v1 |
2019-03-22 | Nonlinear Iterative Hard Thresholding for Inverse Scattering | We consider the inverse scattering problem for sparse scatterers. An image
reconstruction algorithm is proposed that is based on a nonlinear
generalization of iterative hard thresholding. The convergence and error of the
method was analyzed by means of coherence estimates and compared to numerical
simulations. | 1903.10875v1 |
2019-04-06 | Phenomenological description of the dynamics of bipartite antiferromagnets in the limit of strong exchange | The equation of motion of the staggered order parameter is derived in a
step-by-step manner from the coupled Landau-Lifshitz-Gilbert dynamics of
bipartite spin moments in the limit of strong antiferromagnetic exchange
coupling. | 1904.03529v4 |
2019-04-19 | Variational approximation of functionals defined on $1$-dimensional connected sets in $\mathbb{R}^n$ | In this paper we consider the Euclidean Steiner tree problem and, more
generally, (single sink) Gilbert--Steiner problems as prototypical examples of
variational problems involving 1-dimensional connected sets in $\mathbb{R}^n$.
Following the the analysis for the planar case presented in [4], we provide a
variational approximation through Ginzburg--Landau type energies proving a
$\Gamma$-convergence result for $n \geq 3$. | 1904.09328v1 |
2020-03-02 | Improved Gilbert-Varshamov Bound for Entanglement-Assisted Asymmetric Quantum Error Correction by Symplectic Orthogonality | We propose and prove an existential theorem for entanglement-assisted
asymmetric quantum error correction. Then we demonstrate its superiority over
the conventional one. | 2003.00668v2 |
2020-07-14 | Competitively Pricing Parking in a Tree | Motivated by demand-responsive parking pricing systems we consider
posted-price algorithms for the online metrical matching problem and the online
metrical searching problem in a tree metric. Our main result is a poly-log
competitive posted-price algorithm for online metrical searching. | 2007.07294v2 |
2021-05-14 | Very regular solution to Landau-Lifshitz system with spin-polarized transport | In this paper, we provide a precise description of the compatibility
conditions for the initial data so that one can show the existence and
uniqueness of regular short-time solution to the Neumann initial-boundary
problem of a class of Landau-Lifshitz-Gilbert system with spin-polarized
transport, which is a strong nonlinear coupled parabolic system with non-local
energy. | 2105.06616v1 |
2022-09-23 | Limiting Distributions of Sums with Random Spectral Weights | This paper studies the asymptotic properties of weighted sums of the form
$Z_n=\sum_{i=1}^n a_i X_i$, in which $X_1, X_2, \ldots, X_n$ are i.i.d.~random
variables and $a_1, a_2, \ldots, a_n$ correspond to either eigenvalues or
singular values in the classic Erd\H{o}s-R\'enyi-Gilbert model. In particular,
we prove central limit-type theorems for the sequences $n^{-1}Z_n$ with varying
conditions imposed on $X_1, X_2, \ldots, X_n$. | 2209.11389v1 |
2023-09-16 | Expansion of the Critical Intensity for the Random Connection Model | We derive an asymptotic expansion for the critical percolation density of the
random connection model as the dimension of the encapsulating space tends to
infinity. We calculate rigorously the first expansion terms for the Gilbert
disk model, the hyper-cubic model, the Gaussian connection kernel, and a
coordinate-wise Cauchy kernel. | 2309.08830v1 |
2024-03-14 | Remarks on the rate of linear vortex symmetrization | We reformulate results from the paper ``Linear vortex symmetrization: The
spectral density function" by Ionescu and the author in simplified forms and
derive rigorously the bounds given in Bassom and Gilbert (J. Fluid Mech.,
1998), which provided interesting insights on the vortex symmetrization
phenomenon. | 2403.09397v1 |
2003-10-29 | Comparing Chemical Abundances of the Damped Lya Systems and Metal-Poor Stars | I briefly draw comparisons between the fields of damped Lya and metal-poor
stellar abundances. In particular, I examine their complementary
age-metallicity relations and comparisons between the damped Lya and dwarf
galaxy abundance patterns. Regarding the latter, I describe a series of
problems concerning associating high z damped Lya systems with present-day
dwarfs. | 0310850v1 |
2006-12-01 | Stochastic excitation and damping of solar-type oscillations | A review on acoustic mode damping and excitation in solar-type stars is
presented. Current models for linear damping rates are discussed in the light
of recent low-degree solar linewidth measurements with emphasis on the
frequency-dependence of damping rates of low-order modes. Recent developments
in stochastic excitation models are reviewed and tested against the latest
high-quality data of solar-like oscillations, such as from alpha Cen A, and
against results obtained from hydrodynamical simulations. | 0612024v1 |
1997-08-11 | A theoretical study on the damping of collective excitations in a Bose-Einstein condensate | We study the damping of low-lying collective excitations of condensates in a
weakly interacting Bose gas model within the framework of imaginary time path
integral. A general expression of the damping rate has been obtained in the low
momentum limit for both the very low temperature regime and the higher
temperature regime. For the latter, the result is new and applicable to recent
experiments. Theoretical predictions for the damping rate are compared with the
experimental values. | 9708080v3 |
1997-09-24 | Damping in dilute Bose gases: a mean-field approach | Damping in a dilute Bose gas is investigated using a mean-field approximation
which describes the coupled oscillations of condensate and non-condensate atoms
in the collisionless regime. Explicit results for both Landau and Beliaev
damping rates are given for non-uniform gases. In the case of uniform systems
we obtain results for the damping of phonons both at zero and finite
temperature. The isothermal compressibility of a uniform gas is also discussed. | 9709259v1 |
2000-09-01 | Damped Bogoliubov excitations of a condensate interacting with a static thermal cloud | We calculate the damping of condensate collective excitations at finite
temperatures arising from the lack of equilibrium between the condensate and
thermal atoms. We neglect the non-condensate dynamics by fixing the thermal
cloud in static equilibrium. We derive a set of generalized Bogoliubov
equations for finite temperatures that contain an explicit damping term due to
collisional exchange of atoms between the two components. We have numerically
solved these Bogoliubov equations to obtain the temperature dependence of the
damping of the condensate modes in a harmonic trap. We compare these results
with our recent work based on the Thomas-Fermi approximation. | 0009021v2 |
2000-11-20 | Cavity assisted quasiparticle damping in a Bose-Einstein condensate | We consider an atomic Bose-Einstein condensate held within an optical cavity
and interacting with laser fields. We show how the interaction of the cavity
mode with the condensate can cause energy due to excitations to be coupled to a
lossy cavity mode, which then decays, thus damping the condensate, how to
choose parameters for damping specific excitations, and how to target a range
of different excitations to potentially produce extremely cold condensates. | 0011341v2 |
2002-12-16 | The nonlinear damping of Bose-Einstein condensate oscillations at ultra-low temperatures | We analyze the damping of the transverse breathing mode in an elongated trap
at ultralow temperatures. The damping occurs due to the parametric resonance
entailing the energy transfer to the longitudinal degrees of freedom. It is
found that the nonlinear coupling between the transverse and discrete
longitudinal modes can result in an anomalous behavior of the damping as a
function of time with the partially reversed pumping of the breathing mode. The
picture revealed explains the results observed in [16]. | 0212377v2 |
2004-08-27 | Tunable magnetization damping in transition metal ternary alloys | We show that magnetization damping in Permalloy, Ni80Fe20 (``Py''), can be
enhanced sufficiently to reduce post-switching magnetization precession to an
acceptable level by alloying with the transition metal osmium (Os). The damping
increases monotonically upon raising the Os-concentration in Py, at least up to
9% of Os. Other effects of alloying with Os are suppression of magnetization
and enhancement of in-plane anisotropy. Magnetization damping also increases
significantly upon alloying with the five other transition metals included in
this study (4d-elements: Nb, Ru, Rh; 5d-elements: Ta, Pt) but never as strongly
as with Os. | 0408608v1 |
2005-03-06 | Nonlinear damping in nanomechanical beam oscillator | We investigate the impact of nonlinear damping on the dynamics of a
nanomechanical doubly clamped beam. The beam is driven into nonlinear regime
and the response is measured by a displacement detector. For data analysis we
introduce a nonlinear damping term to Duffing equation. The experiment shows
conclusively that accounting for nonlinear damping effects is needed for
correct modeling of the nanomechanical resonators under study. | 0503130v2 |
2006-05-23 | The origin of increase of damping in transition metals with rare earth impurities | The damping due to rare earth impurities in transition metals is discussed in
the low concentration limit. It is shown that the increase in damping is mainly
due to the coupling of the orbital moments of the rare earth impurities and the
conduction $p$-electrons. It is shown that an itinerant picture for the host
transition ions is needed to reproduce the observed dependence of the damping
on the total angular moment of the rare earths. | 0605583v1 |
2001-05-14 | Simplified models of electromagnetic and gravitational radiation damping | In previous work the authors analysed the global properties of an approximate
model of radiation damping for charged particles. This work is put into context
and related to the original motivation of understanding approximations used in
the study of gravitational radiation damping. It is examined to what extent the
results obtained previously depend on the particular model chosen. Comparisons
are made with other models for gravitational and electromagnetic fields. The
relation of the kinetic model for which theorems were proved to certain
many-particle models with radiation damping is exhibited. | 0105045v1 |
1994-06-07 | Damping Rate of a Yukawa Fermion at Finite Temperature | The damping of a massless fermion coupled to a massless scalar particle at
finite temperature is considered using the Braaten-Pisarski resummation
technique. First the hard thermal loop diagrams of this theory are extracted
and effective Green's functions are constructed. Using these effective Green's
functions the damping rate of a soft Yukawa fermion is calculated. This rate
provides the most simple example for the damping of a soft particle. To leading
order it is proportional to $g^2T$, whereas the one of a hard fermion is of
higher order. | 9406242v1 |
2006-05-02 | Moduli decay in the hot early Universe | We consider moduli fields interacting with thermalized relativistic matter.
We determine the temperature dependence of their damping rate and find it is
dominated by thermal effects in the high temperature regime, i.e. for
temperatures larger than their mass. For a simple scalar model the damping rate
is expressed through the known matter bulk viscosity. The high temperature
damping rate is always smaller than the Hubble rate, so that thermal effects
are not sufficient for solving the cosmological moduli problem. | 0605030v2 |
2006-11-27 | Inviscid limit for damped and driven incompressible Navier-Stokes equations in ${{\mathbb R}^2}$ | We consider the zero viscosity limit of long time averages of solutions of
damped and driven Navier-Stokes equations in ${\mathbb R}^2$. We prove that the
rate of dissipation of enstrophy vanishes. Stationary statistical solutions of
the damped and driven Navier-Stokes equations converge to renormalized
stationary statistical solutions of the damped and driven Euler equations.
These solutions obey the enstrophy balance. | 0611782v1 |
2003-09-09 | Traveling solitons in the damped driven nonlinear Schrödinger equation | The well known effect of the linear damping on the moving nonlinear
Schr\"odinger soliton (even when there is a supply of energy via the spatially
homogeneous driving) is to quench its momentum to zero. Surprisingly, the zero
momentum does not necessarily mean zero velocity. We show that two or more
parametrically driven damped solitons can form a complex traveling with zero
momentum at a nonzero constant speed.
All traveling complexes we have found so far, turned out to be unstable.
Thus, the parametric driving is capable of sustaining the uniform motion of
damped solitons, but some additional agent is required to stabilize it. | 0309031v1 |
2001-11-25 | The Landau Damping Effect and Complex-valued Nature of Physical Quantities | Within the framework of the hypothesis offered by authors about
complex-valued nature of physical quantities, the effect of the Landau damping
has been explored with assumption that not only frequency can be a small
imaginary component but also a wave vector. The numerical solution of the
obtained dispersion equation testifies that uncollisional damping is
accompanied in a certain region of space by antidumping of waves, and in
particular situations antidumping may prevail over damping. It is possible that
this effect may explain the experimental difficulties connected with inhibition
of instabilities of plasma in the problem of controllable thermonuclear fusion. | 0111176v1 |
2005-10-14 | Nontrapping arrest of Langmuir wave damping near the threshold amplitude | Evolution of a Langmuir wave is studied numerically for finite amplitudes
slightly above the threshold which separates damping from nondamping cases.
Arrest of linear damping is found to be a second-order effect due to ballistic
evolution of perturbations, resonant power transfer between field and
particles, and organization of phase space into a positive slope for the
average distribution function $f_{av}$ around the resonant wave phase speed
$v_\phi$. Near the threshold trapping in the wave potential does not arrest
damping or saturate the subsequent growth phase. | 0510131v3 |
2000-06-22 | Decoherence and Entanglement in Two-mode Squeezed Vacuum States | I investigate the decoherence of two-mode squeezed vacuum states by analyzing
the relative entropy of entanglement. I consider two sources of decoherence:
(i) the phase damping and (ii) the amplitude damping due to the coupling to the
thermal environment. In particular, I give the exact value of the relative
entropy of entanglement for the phase damping model. For the amplitude damping
model, I give an upper bound for the relative entropy of entanglement, which
turns out to be a good approximation for the entanglement measure in usual
experimental situations. | 0006100v1 |
2006-08-02 | Damped Population Oscillation in a Spontaneously Decaying Two-Level Atom Coupled to a Monochromatic Field | We investigate the time evolution of atomic population in a two-level atom
driven by a monochromatic radiation field, taking spontaneous emission into
account. The Rabi oscillation exhibits amplitude damping in time caused by
spontaneous emission. We show that the semiclassical master equation leads in
general to an overestimation of the damping rate and that a correct
quantitative description of the damped Rabi oscillation can thus be obtained
only with a full quantum mechanical theory. | 0608020v1 |
2007-08-28 | Linear frictional forces cause orbits to neither circularize nor precess | For the undamped Kepler potential the lack of precession has historically
been understood in terms of the Runge-Lenz symmetry. For the damped Kepler
problem this result may be understood in terms of the generalization of Poisson
structure to damped systems suggested recently by Tarasov[1]. In this
generalized algebraic structure the orbit-averaged Runge-Lenz vector remains a
constant in the linearly damped Kepler problem to leading order in the damping
coe | 0708.3827v3 |
2008-12-11 | Frequency-dependent Drude damping in Casimir force calculations | The Casimir force is calculated between Au thin films that are described by a
Drude model with a frequency dependent damping function. The model parameters
are obtained from available experimental data for Au thin films. Two cases are
considered; annealed and nonannealed films that have a different damping
function. Compared with the calculations using a Drude model with a constant
damping parameter, we observe changes in the Casimir force of a few percent.
This behavior is only observed in films of no more than 300 $\AA$ thick. | 0812.2209v1 |
2008-12-18 | Dipole Oscillations of a Fermi Gas in a Disordered Trap: Damping and Localization | We theoretically study the dipole oscillations of an ideal Fermi gas in a
disordered trap. We show that even weak disorder induces strong damping of the
oscillations and we identify a metal-insulator crossover. For very weak
disorder, we show that damping results from a dephasing effect related to weak
random perturbations of the energy spectrum. For increasing disorder, we show
that the Fermi gas crosses over to an insulating regime characterized by
strong-damping due to the proliferation of localized states. | 0812.3501v2 |
2009-03-11 | Confronting the damping of the baryon acoustic oscillations with observation | We investigate the damping of the baryon acoustic oscillations in the matter
power spectrum due to the quasinonlinear clustering and redshift-space
distortions by confronting the models with the observations of the Sloan
Digital Sky Survey luminous red galaxy sample. The chi-squared test suggests
that the observed power spectrum is better matched by models with the damping
of the baryon acoustic oscillations rather than the ones without the damping. | 0903.1883v1 |
2009-04-10 | Spectral deviations for the damped wave equation | We prove a Weyl-type fractal upper bound for the spectrum of the damped wave
equation, on a negatively curved compact manifold. It is known that most of the
eigenvalues have an imaginary part close to the average of the damping
function. We count the number of eigenvalues in a given horizontal strip
deviating from this typical behaviour; the exponent that appears naturally is
the `entropy' that gives the deviation rate from the Birkhoff ergodic theorem
for the geodesic flow. A Weyl-type lower bound is still far from reach; but in
the particular case of arithmetic surfaces, and for a strong enough damping, we
can use the trace formula to prove a result going in this direction. | 0904.1736v1 |
2009-10-26 | Pressure Fronts in 1D Damped Nonlinear Lattices | The propagation of pressure fronts (impact solutions) in 1D chains of atoms
coupled by anharmonic potentials between nearest neighbor and submitted to
damping forces preserving uniform motion, is investigated. Travelling fronts
between two regions at different uniform pressures are found numerically and
well approximate analytically. It is proven that there are three analytical
relations between the impact velocity, the compression, the front velocity and
the energy dissipation which only depend on the coupling potential and are
\textit{independent} of the damping. Such travelling front solutions cannot
exist without damping. | 0910.4890v1 |
2009-11-05 | Bloch oscillations in lattice potentials with controlled aperiodicity | We numerically investigate the damping of Bloch oscillations in a
one-dimensional lattice potential whose translational symmetry is broken in a
systematic manner, either by making the potential bichromatic or by introducing
scatterers at distinct lattice sites. We find that the damping strongly depends
on the ratio of lattice constants in the bichromatic potential, and that even a
small concentration of scatterers can lead to strong damping. Moreover,
mean-field interactions are able to counteract aperiodicity-induced damping of
Bloch oscillations. | 0911.1108v3 |
2010-01-12 | Decoherence and damping in ideal gases | The particle and current densities are shown to display damping and undergo
decoherence in ideal quantum gases. The damping is read off from the equations
of motion reminiscent of the Navier-Stokes equations and shows some formal
similarity with Landau damping. The decoherence leads to consistent density and
current histories with characteristic length and time scales given by the ideal
gas. | 1001.1803v2 |
2010-05-14 | The effect of spin magnetization in the damping of electron plasma oscillations | The effect of spin of particles in the propagation of plasma waves is studied
using a semi-classical kinetic theory for a magnetized plasma. We focus in the
simple damping effects for the electrostatic wave modes besides Landau damping.
Without taking into account more quantum effects than spin contribution to
Vlasov's equation, we show that spin produces a new damping or instability
which is proportional to the zeroth order magnetization of the system. This
correction depends on the electromagnetic part of the wave which is coupled
with the spin vector. | 1005.2573v1 |
2010-06-01 | Recent Progress on a Manifold Damped and Detuned Structure for CLIC | A damped detuned structure for the main X-band linacs of CLIC is being
investigated as an alternative design to the present baseline heavily damped
structure. In our earlier designs we studied detuned structures, operating at
11.994 GHz, with a range of dipole bandwidths in order to ensure the structure
satisfies beam dynamics and rf breakdown constraints. Here we report on the
development of a damped and detuned structure which satisfies both constraints.
Preparations for high power testing of the structure are also discussed | 1006.0087v1 |
2010-07-21 | Finite temperature damping of collective modes of a BCS-BEC crossover superfluid | A new mechanism is proposed to explain the puzzling damping of collective
excitations, which was recently observed in the experiments of strongly
interacting Fermi gases below the superfluid critical temperature on the
fermionic (BCS) side of Feshbach resonance. Sound velocity, superfluid density
and damping rate are calculated with effective field theory. We find that a
dominant damping process is due to the interaction between superfluid phonons
and thermally excited fermionic quasiparticles, in contrast to the previously
proposed pair-breaking mechanism. Results from our effective model are compared
quantitatively with recent experimental findings, showing a good agreement. | 1007.3694v2 |
2010-08-04 | Confinement induced by fermion damping in three-dimensional QED | The three-dimensional non-compact QED is known to exhibit weak confinement
when fermions acquire a finite mass via the mechanism of dynamical chiral
symmetry breaking. In this paper, we study the effect of fermion damping caused
by elastic scattering on the classical potential between fermions. By
calculating the vacuum polarization function that incorporates the fermion
damping effect, we show that fermion damping can induce a weak confinement even
when the fermions are massless and the chiral symmetry is not broken. | 1008.0736v2 |
2011-06-22 | Highly Damped Quasinormal Modes and the Small Scale Structure of Quantum Corrected Black Hole Exteriors | Quasinormal modes provide valuable information about the structure of
spacetime outside a black hole. There is also a conjectured relationship
between the highly damped quasinormal modes and the semi-classical spectrum of
the horizon area/entropy. In this paper, we show that for spacetimes
characterized by more than one scale, the "infinitely damped" modes in
principle probe the structure of spacetime outside the horizon at the shortest
length scales. We demonstrate this with the calculation of the highly damped
quasinormal modes of the non-singular, single horizon, quantum corrected black
hole derived in [14]. | 1106.4357v1 |
2012-02-20 | Simple Non-Markovian Microscopic Models for the Depolarizing Channel of a Single Qubit | The archetypal one-qubit noisy channels ---depolarizing, phase-damping and
amplitude-damping channels--- describe both Markovian and non-Markovian
evolution. Simple microscopic models for the depolarizing channel, both
classical and quantum, are considered. Microscopic models which describe phase
damping and amplitude damping channels are briefly reviewed. | 1202.4210v4 |
2012-05-11 | On radiative damping in plasma-based accelerators | Radiative damping in plasma-based electron accelerators is analyzed. The
electron dynamics under combined influence of the constant accelerating force
and the classical radiation reaction force is studied. It is shown that
electron acceleration cannot be limited by radiation reaction. If initially the
accelerating force was stronger than the radiation reaction force then the
electron acceleration is unlimited. Otherwise the electron is decelerated by
radiative damping up to a certain instant of time and then accelerated without
limits. Regardless of the initial conditions the infinite-time asymptotic
behavior of an electron is governed by self-similar solution providing
unlimited acceleration. The relative energy spread induced by the radiative
damping decreases with time in the infinite-time limit. | 1205.2436v1 |
2012-06-14 | Damping of optomechanical disks resonators vibrating in air | We report on miniature GaAs disk optomechanical resonators vibrating in air
in the radiofrequency range. The flexural modes of the disks are studied by
scanning electron microscopy and optical interferometry, and correctly modeled
with the elasticity theory for annular plates. The mechanical damping is
systematically measured, and confronted with original analytical models for air
damping. Formulas are derived that correctly reproduce both the mechanical
modes and the damping behavior, and can serve as design tools for
optomechanical applications in fluidic environment. | 1206.3032v1 |
2012-07-09 | A Generalized Interpolation Inequality and its Application to the Stabilization of Damped Equations | In this paper, we establish a generalized H{\"o}lder's or interpolation
inequality for weighted spaces in which the weights are non-necessarily
homogeneous. We apply it to the stabilization of some damped wave-like
evolution equations. This allows obtaining explicit decay rates for smooth
solutions for more general classes of damping operators. In particular, for
$1-d$ models, we can give an explicit decay estimate for pointwise damping
mechanisms supported on any strategic point. | 1207.2030v2 |
2012-07-10 | Conformation dependent damping and generalization of fluctuation-dissipation relation | Damping on an object generally depends on its conformation (shape size etc.).
We consider the Langevin dynamics of a model system with a conformation
dependent damping and generalize the fluctuation dissipation relation to fit in
such a situation. We derive equilibrium distribution function for such a case
which converges to the standard Boltzmann form at the limit of uniform damping.
The results can have implications, in general, for barrier overcoming processes
where standard Boltzmann statistics is slow. | 1207.2218v2 |
2012-10-30 | On algebraic damping close to inhomogeneous Vlasov equilibria in multi-dimensional spaces | We investigate the asymptotic damping of a perturbation around inhomogeneous
stable stationary states of the Vlasov equation in spatially multi-dimensional
systems. We show that branch singularities of the Fourier-Laplace transform of
the perturbation yield algebraic dampings. In two spatial dimensions, we
classify the singularities and compute the associated damping rate and
frequency. This 2D setting also applies to spherically symmetric
self-gravitating systems. We validate the theory using a toy model and an
advection equation associated with the isochrone model, a model of spherical
self-gravitating systems. | 1210.8040v1 |
2013-04-07 | Phenomenological model of anomalous magnon softening and damping in half-metallic manganites | To describe anomalous zone-boundary softening and damping of magnons in
manganites we present a phenomenological two-fluid model containing
ferromagnetic Fermi-liquid and non-Fermi-liquid components. The Fermi-liquid
component accounts for softening of zone-boundary magnons and for the Landau
damping of magnons in the Stoner continuum arising at low frequencies due to
zero-point effects. Coupling of the Fermi-liquid and non-Fermi-liquid fluids
yields conventional long wavelength magnons damped due to their coupling with
longitudinal spin fluctuations. | 1304.1983v1 |
2013-04-25 | Determination of Transverse Density Structuring from Propagating MHD Waves in the Solar Atmosphere | We present a Bayesian seismology inversion technique for propagating
magnetohydrodynamic (MHD) transverse waves observed in coronal waveguides. The
technique uses theoretical predictions for the spatial damping of propagating
kink waves in transversely inhomogeneous coronal waveguides. It combines wave
amplitude damping length scales along the waveguide with theoretical results
for resonantly damped propagating kink waves to infer the plasma density
variation across the oscillating structures. Provided the spatial dependence of
the velocity amplitude along the propagation direction is measured and the
existence of two different damping regimes is identified, the technique would
enable us to fully constrain the transverse density structuring, providing
estimates for the density contrast and its transverse inhomogeneity length
scale. | 1304.6869v1 |
2013-07-08 | Optimal decay rate of the bipolar Euler-Poisson system with damping in $\mathbb{R}^3$ | By rewriting a bipolar Euler-Poisson equations with damping into an Euler
equation with damping coupled with an Euler-Poisson equation with damping, and
using a new spectral analysis, we obtain the optimal decay results of the
solutions in $L^2$-norm, which improve theose in \cite{Li3, Wu3}. More
precisely, the velocities $u_1,u_2$ decay at the $L^2-$rate $(1+t)^{-{5}{4}}$,
which is faster than the normal $L^2-$rate $(1+t)^{-{3}{4}}$ for the Heat
equation and the Navier-Stokes equations. In addition, the disparity of two
densities $\rho_1-\rho_2$ and the disparity of two velocities $u_1-u_2$ decay
at the $L^2$-rate $(1+t)^{-2}$. | 1307.2081v1 |
2013-07-27 | Symmetry considerations on radiation damping | It is well known that a direct Lagrangian description of radiation damping is
still missing. In this paper we will use a specific approach of this problem
which is the standard way to treat the radiation damping problem. The
objectives here are to construct: a N=2 supersymmetric extension for the model
describing the radiation damping on the noncommutative plane with electric and
magnetic interactions; a dualization analysis of the original action; the
supercharge algebra and the total Hamiltonian for the system. | 1307.7319v1 |
2014-02-10 | Damping of a nanocantilever by paramagnetic spins | We compute damping of mechanical oscillations of a cantilever that contains
flipping paramagnetic spins. This kind of damping is mandated by the dynamics
of the total angular momentum, spin + mechanical. Rigorous expression for the
damping rate is derived in terms of measurable parameters. The effect of spins
on the quality factor of the cantilever can be significant in cantilevers of
small length that have large concentration of paramagnetic spins of atomic
and/or nuclear origin. | 1402.2326v1 |
2014-02-20 | Long-time behavior of solutions of a BBM equation with generalized damping | We study the long-time behavior of the solution of a damped BBM equation $u_t
+ u_x - u_{xxt} + uu_x + \mathscr{L}_{\gamma}(u) = 0$. The proposed dampings
$\mathscr{L}_{\gamma}$ generalize standards ones, as parabolic
($\mathscr{L}_{\gamma}(u)=-\Delta u$) or weak damping
($\mathscr{L}_{\gamma}(u)=\gamma u$) and allows us to consider a greater range.
After establish the local well-posedness in the energy space, we investigate
some numerical properties. | 1402.5009v1 |
2014-02-24 | N=2 supersymmetric radiation damping problem on a noncommutative plane | It is well known that a direct Lagrangian description of radiation damping is
still missing. In this paper a specific approach of this problem was used,
which is the standard way to treat the radiation damping problem. A $N=2$
supersymmetric extension for the model describing the radiation damping on the
noncommutative plane with electric and magnetic interactions was obtained. The
entire supercharge algebra and the total Hamiltonian for the system were
analyzed. Finally, noncommutativity features were introduced and its
consequences were explored.. | 1402.6996v1 |
2014-11-03 | Renormalized solutions to the continuity equation with an integrable damping term | We consider the continuity equation with a nonsmooth vector field and a
damping term. In their fundamental paper, DiPerna and Lions proved that, when
the damping term is bounded in space and time, the equation is well posed in
the class of distributional solutions and the solution is transported by
suitable characteristics of the vector field. In this paper, we prove existence
and uniqueness of renormalized solutions in the case of an integrable damping
term, employing a new logarithmic estimate inspired by analogous ideas of
Ambrosio, Lecumberry, and Maniglia, Crippa and De Lellis in the Lagrangian
case. | 1411.0451v1 |
2015-02-07 | Landau Damping in a Mixture of Bose and Fermi Superfluids | We study the Landau damping in Bose-Fermi superfluid mixture at finite
temperature. We find that at low temperature, the Landau damping rate will be
exponentially suppressed at both the BCS side and the BEC side of Fermi
superfluid. The momentum dependence of the damping rate is obtained, and it is
quite different from the BCS side to the BEC side. The relations between our
result and collective mode experiment in the recently realized Bose-Fermi
superfluid mixture are also discussed. | 1502.02116v1 |
2015-03-20 | Applying a formula for generator redispatch to damp interarea oscillations using synchrophasors | If an interarea oscillatory mode has insufficient damping, generator
redispatch can be used to improve its damping. We explain and apply a new
analytic formula for the modal sensitivity to rank the best pairs of generators
to redispatch. The formula requires some dynamic power system data and we show
how to obtain that data from synchrophasor measurements. The application of the
formula to damp interarea modes is explained and illustrated with interarea
modes of the New England 10-machine power system. | 1503.06144v2 |
2016-01-21 | Codeword Stabilized Quantum Codes for Asymmetric Channels | We discuss a method to adapt the codeword stabilized (CWS) quantum code
framework to the problem of finding asymmetric quantum codes. We focus on the
corresponding Pauli error models for amplitude damping noise and phase damping
noise. In particular, we look at codes for Pauli error models that correct one
or two amplitude damping errors. Applying local Clifford operations on graph
states, we are able to exhaustively search for all possible codes up to length
$9$. With a similar method, we also look at codes for the Pauli error model
that detect a single amplitude error and detect multiple phase damping errors.
Many new codes with good parameters are found, including nonadditive codes and
degenerate codes. | 1601.05763v1 |
2016-02-08 | On Boundary Damped Inhomogeneous Timoshenko Beams and Related Problems | We consider the model equations for the Timoshenko beam as a first order
system in the framework of evolutionary equations. The focus is on boundary
damping, which is implemented as a dynamic boundary condition. A change of
material laws allows to include a large class of cases of boundary damping. By
choosing a particular material law, it is shown that the first order approach
to Sturm-Liouville problems with boundary damping is also covered. | 1602.02521v1 |
2016-02-13 | Diffusion phenomena for the wave equation with space-dependent damping in an exterior domain | In this paper, we consider the asymptotic behavior of solutions to the wave
equation with space-dependent damping in an exterior domain. We prove that when
the damping is effective, the solution is approximated by that of the
corresponding heat equation as time tends to infinity. Our proof is based on
semigroup estimates for the corresponding heat equation and weighted energy
estimates for the damped wave equation. The optimality of the decay late for
solutions is also established. | 1602.04318v1 |
2016-02-29 | Robust quantum state recovery from amplitude damping within a mixed states framework | Due to the interaction with the environment, a quantum state is subjected to
decoherence which becomes one of the biggest problems for practical quantum
computation. Amplitude damping is one of the most important decoherence
processes. Here, we show that general two-qubit mixed states undergoing an
amplitude damping can be almost completely restored using a reversal procedure.
This reversal procedure through CNOT and Hadamard gates, could also protect the
entanglement of two-qubit mixed states, when it undergoes general amplitude
damping. Moreover, in the presence of uncertainty in the underlying system, we
propose a robust recovering method with optimal characteristics of the problem. | 1602.08865v1 |
2016-05-23 | Large time behaivor of global solutions to nonlinear wave equations with frictional and viscoelastic damping terms | In this paper, we study the Cauchy problem for a nonlinear wave equation with
frictional and viscoelastic damping terms. As is pointed out by [8], in this
combination, the frictional damping term is dominant for the viscoelastic one
for the global dynamics of the linear equation. In this note we observe that if
the initial data is small, the frictional damping term is again dominant even
in the nonlinear equation case. In other words, our main result is diffusion
phenomena: the solution is approximated by the heat kernel with a suitable
constant. Our proof is based on several estimates for the corresponding linear
equations. | 1605.07232v1 |
2016-07-21 | Protecting and enhancing spin squeezing under decoherence using weak measurement | We propose an efficient method to protect spin squeezing under the action of
amplitude-damping, depolarizing and phase-damping channels based on measurement
reversal from weak measurement, and consider an ensemble of N independent
spin-1/2 particles with exchange symmetry. We find that spin squeezing can be
enhanced greatly under three different decoherence channels and spin-squeezing
sudden death (SSSD) can be avoided undergoing amplitude damping and
phase-damping channels. | 1607.06530v2 |
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