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2005-06-11 | Quantum damped oscillator II: Bateman's Hamiltonian vs. 2D Parabolic Potential Barrier | We show that quantum Bateman's system which arises in the quantization of a
damped harmonic oscillator is equivalent to a quantum problem with 2D parabolic
potential barrier known also as 2D inverted isotropic oscillator. It turns out
that this system displays the family of complex eigenvalues corresponding to
the poles of analytical continuation of the resolvent operator to the complex
energy plane. It is shown that this representation is more suitable than the
hyperbolic one used recently by Blasone and Jizba. | 0506091v1 |
2005-06-27 | Entanglement of pair cat states and teleportation | The entanglement of pair cat states in the phase damping channel is studied
by employing the relative entropy of entanglement. It is shown that the pair
cat states can always be distillable in the phase damping channel. Furthermore,
we analyze the fidelity of teleportation for the pair cat states by using joint
measurements of the photon-number sum and phase difference. | 0506217v1 |
2005-07-21 | Entanglement versus mixedness for coupled qubits under a phase damping channel | Quantification of entanglement against mixing is given for a system of
coupled qubits under a phase damping channel. A family of pure initial joint
states is defined, ranging from pure separable states to maximally entangled
state. An ordering of entanglement measures is given for well defined initial
state amount of entanglement. | 0507212v2 |
2005-10-20 | Overdamping by weakly coupled environments | A quantum system weakly interacting with a fast environment usually undergoes
a relaxation with complex frequencies whose imaginary parts are damping rates
quadratic in the coupling to the environment, in accord with Fermi's ``Golden
Rule''. We show for various models (spin damped by harmonic-oscillator or
random-matrix baths, quantum diffusion, quantum Brownian motion) that upon
increasing the coupling up to a critical value still small enough to allow for
weak-coupling Markovian master equations, a new relaxation regime can occur. In
that regime, complex frequencies lose their real parts such that the process
becomes overdamped. Our results call into question the standard belief that
overdamping is exclusively a strong coupling feature. | 0510164v1 |
2006-06-07 | Comment on "Optimum Quantum Error Recovery using Semidefinite Programming" | In a recent paper ([1]=quant-ph/0606035) it is shown how the optimal recovery
operation in an error correction scheme can be considered as a semidefinite
program. As a possible future improvement it is noted that still better error
correction might be obtained by optimizing the encoding as well. In this note
we present the result of such an improvement, specifically for the four-bit
correction of an amplitude damping channel considered in [1]. We get a strict
improvement for almost all values of the damping parameter. The method (and the
computer code) is taken from our earlier study of such correction schemes
(quant-ph/0307138). | 0606059v1 |
2006-10-16 | Local noise can enhance entanglement teleportation | Recently we have considered two-qubit teleportation via mixed states of four
qubits and defined the generalized singlet fraction. For single-qubit
teleportation, Badziag {\em et al.} [Phys. Rev. A {\bf 62}, 012311 (2000)] and
Bandyopadhyay [Phys. Rev. A {\bf 65}, 022302 (2002)] have obtained a family of
entangled two-qubit mixed states whose teleportation fidelity can be enhanced
by subjecting one of the qubits to dissipative interaction with the environment
via an amplitude damping channel. Here, we show that a dissipative interaction
with the local environment via a pair of time-correlated amplitude damping
channels can enhance fidelity of entanglement teleportation for a class of
entangled four-qubit mixed states. Interestingly, we find that this enhancement
corresponds to an enhancement in the quantum discord for some states. | 0610125v1 |
2006-11-24 | High fidelity transfer of an arbitrary quantum state between harmonic oscillators | It is shown that by switching a specific time-dependent interaction between a
harmonic oscillator and a transmission line (a waveguide, an optical fiber,
etc.) the quantum state of the oscillator can be transferred into that of
another oscillator coupled to the distant other end of the line, with a
fidelity that is independent of the initial state of both oscillators. For a
transfer time $T$, the fidelity approaches 1 exponentially in $\gamma T$ where
$\gamma$ is a characteristic damping rate. Hence, a good fidelity is achieved
even for a transfer time of a few damping times. Some implementations are
discussed. | 0611249v1 |
2006-12-05 | Quantum Brownian motion and the second law of thermodynamics | We consider a single harmonic oscillator coupled to a bath at zero
temperature. As is well known, the oscillator then has a higher average energy
than that given by its ground state. Here we show analytically that for a
damping model with arbitrarily discrete distribution of bath modes and damping
models with continuous distributions of bath modes with cut-off frequencies,
this excess energy is less than the work needed to couple the system to the
bath, therefore, the quantum second law is not violated. On the other hand, the
second law may be violated for bath modes without cut-off frequencies, which
are, however, physically unrealistic models. | 0612038v1 |
2007-05-08 | Minimal qudit code for a qubit in the phase-damping channel | Using the stabilizer formalism we construct the minimal code into a
D-dimensional Hilbert space (qudit) to protect a qubit against phase damping.
The effectiveness of this code is then studied by means of input-output
fidelity. | 0705.1099v3 |
2007-05-10 | Anomalous Diffusion of particles with inertia in external potentials | Recently a new type of Kramers-Fokker-Planck Equation has been proposed [R.
Friedrich et al. Phys. Rev. Lett. {\bf 96}, 230601 (2006)] describing anomalous
diffusion in external potentials. In the present paper the explicit cases of a
harmonic potential and a velocity-dependend damping are incorporated. Exact
relations for moments for these cases are presented and the asymptotic
behaviour for long times is discussed. Interestingly the bounding potential and
the additional damping by itself lead to a subdiffussive behaviour, while
acting together the particle becomes localized for long times. | 0705.1480v1 |
2007-06-13 | Polymers in a vacuum | In a variety of situations, isolated polymer molecules are found in a vacuum
and here we examine their properties. Angular momentum conservation is shown to
significantly alter the average size of a chain and its conservation is only
broken slowly by thermal radiation. The time autocorrelation for monomer
position oscillates with a characteristic time proportional to chain length.
The oscillations and damping are analyzed in detail. Short range repulsive
interactions suppress oscillations and speed up relaxation but stretched chains
still show damped oscillatory time correlations. | 0706.2001v1 |
2007-07-15 | Enhancement of Carrier Mobility in Semiconductor Nanostructures by Dielectric Engineering | We propose a technique for achieving large improvements in carrier mobilities
in 2- and 1-dimensional semiconductor nanostructures by modifying their
dielectric environments. We show that by coating the nanostructures with
high-$\kappa$ dielectrics, scattering from Coulombic impurities can be strongly
damped. Though screening is also weakened, the damping of Coulombic scattering
is much larger, and the resulting improvement in mobilities of carriers can be
as much as an order of magnitude for thin 2D semiconductor membranes, and more
for semiconductor nanowires. | 0707.2244v1 |
2007-07-23 | Causal vs. Noncausal Description of Nonlinear Wave Mixing; Resolving the Damping-Sign Controversy | Frequency-domain nonlinear wave mixing processes may be described either
using response functions whereby the signal is generated after all interactions
with the incoming fields, or in terms of scattering amplitudes where all fields
are treated symetrically with no specific time ordering. Closed Green's
function expressions derived for the two types of signals have different
analytical properties. The recent controversy regarding the sign of radiative
damping in the linear (Kramers Heisenberg) formula is put in a broader context. | 0707.3458v1 |
2007-07-27 | Excitation of spin dynamics by spin-polarized current in vortex state disks | A spin-polarized current with the polarization perpendicular to the plane of
a vortex-state disk results in renormalization of the effective damping for a
given magnetization mode, and the effective damping becomes zero if the current
exceeds a threshold value. The lowest threshold current corresponds to the
lowest frequency vortex gyroscopic mode. For larger values of the current the
dynamic magnetization state is characterized by precession of the vortex around
the dot center with non-small amplitude and higher frequency. | 0707.4128v1 |
2007-09-11 | Frequency and damping of the Scissors Mode of a Fermi gas | We calculate the frequency and damping of the scissors mode in a classical
gas as a function of temperature and coupling strength. Our results show good
agreement with the main features observed in recent measurements of the
scissors mode in an ultracold gas of $^6$Li atoms. The comparison between
theory and experiment involves no fitting parameters and thus allows an
identification of non-classical effects at and near the unitarity limit. | 0709.1617v2 |
2007-09-14 | Strong collisionless damping of the low-velocity branch of electromagnetic wave in plasmas with Maxwellian-like electron velocity distribution function | After approximate replacing of Maxwellian distribution exponent with the
rational polynomial fraction we have obtained precise analytical expression for
and calculated the principal value of logarithmically divergent integral in the
electron wave dispersion equation. At the same time our calculations have shown
the presence of strong collisionless damping of the electromagnetic
low-velocity (electron) wave in plasmas with Maxwellian-like electron velocity
distribution function at some small, of the order of several per cents,
differences from Maxwellian distribution in the main region of large electron
densities, however due to the differences in the distribution tail, where
electron density itself is negligibly small. | 0709.2206v1 |
2007-09-14 | Plasmons, plasminos and Landau damping in a quasiparticle model of the quark-gluon plasma | A phenomenological quasiparticle model is surveyed for 2+1 quark flavors and
compared with recent lattice QCD results. Emphasis is devoted to the effects of
plasmons, plasminos and Landau damping. It is shown that thermodynamic bulk
quantities, known at zero chemical potential, can uniquely be mapped towards
nonzero chemical potential by means of a thermodynamic consistency condition
and a stationarity condition. | 0709.2262v2 |
2007-10-04 | Activation of additional energy dissipation processes in the magnetization dynamics of epitaxial chromium dioxide films | The precessional magnetization dynamics of a chromium dioxide$(100)$ film is
examined in an all-optical pump-probe setup. The frequency dependence on the
external field is used to extract the uniaxial in-plane anisotropy constant.
The damping shows a strong dependence on the frequency, but also on the laser
pump fluency, which is revealed as an important experiment parameter in this
work: above a certain threshold further channels of energy dissipation open and
the damping increases discontinuously. This behavior might stem from spin-wave
instabilities. | 0710.0986v2 |
2007-10-24 | Spin dynamics of a trapped spin-1 Bose Gas above the Bose-Einstein transition temperature | We study collective spin oscillations in a spin-1 Bose gas above the
Bose-Einstein transition temperature. Starting from the Heisenberg equation of
motion, we derive a kinetic equation describing the dynamics of a thermal gas
with the spin-1 degree of freedom. Applying the moment method to the kinetic
equation, we study spin-wave collective modes with dipole symmetry. The dipole
modes in the spin-1 system are found to be classified into the three type of
modes. The frequency and damping rate are obtained as functions of the peak
density. The damping rate is characterized by three relaxation times associated
with collisions. | 0710.4419v2 |
2007-11-19 | Nonlinear mode conversion in monodomain magnetic squares | Modifications of spatial distributions of dynamic magnetization corresponding
to spinwave eigenmodes of magnetic squares subjected to a strong microwave
excitation field have been studied experimentally and theoretically. We show
that an increase of the excitation power leads to a nonlinear generation of
long-wavelength spatial harmonics caused by the nonlinear cross coupling
between the eigenmodes. The analysis of the experimental data shows that this
process is mainly governed by the action of the nonlinear spin-wave damping.
This conclusion is further supported by the numerical calculations based on the
complex Ginzburg-Landau equation phenomenologically taking into account the
nonlinear damping. | 0711.2872v1 |
2007-12-18 | Weibel Instabilities in Dense Quantum Plasmas | The quantum effect on the Weibel instability in an unmagnetized plasma is
presented. Our analysis shows that the quantum effect tends to stabilize the
Weibel instability in the hydrodynamic regime, whereas it produces a new
oscillatory instability in the kinetic regime. A novel effect the quantum
damping, which is associated with the Landau damping, is disclosed. The new
quantum Weibel instability may be responsible for the generation of
non-stationary magnetic fields in compact astrophysical objects as well as in
the forthcoming intense laser-solid density plasma experiments. | 0712.2874v1 |
2008-01-18 | A qualitative perspective on the dynamics of a single-Cooper-pair box with a phase-damped cavity | In a recent paper Dajka, et.al., [J. Phys. A \textbf{40}, F879 (2007)]
predicted that some composite systems can be entangled forever even if coupled
with a thermal bath. We analyze the transient entanglement of a
single-Cooper-pair box biased by a classical voltage and irradiated by a
quantized field and find the unusual feature that the phase-damped cavity can
lead to a long-lived entanglement. The results show an asymptotic value of the
idempotency defect (concurrence) which embodies coherence loss (entanglement
survival), independent of the interaction development by dependent critically
on environment. | 0801.2905v2 |
2008-02-28 | Current driven spin-wave instability triggered by the anomalous Hall effect | We studied the effect of strong electric current on spin waves interacting
relativistically with the current. The spin-wave spectrum is calculated at
arbitrary direction of the wave vector. It is shown that the alternating Hall
current generated by the alternating magnetic moment of the spin waves, reduces
the spin-wave damping. At strong enough unpolarized dc current the damping
changes sign, and the spin-wave amplitude starts to increase exponentially fast
with time. The critical current for the spin-wave instability is determined
mainly by the anomalous Hall effect, and can be much smaller than that for the
spin-torque mechanism of instability. | 0802.4150v1 |
2008-03-31 | Spectral Modeling of Magnetohydrodynamic Turbulent Flows | We present a dynamical spectral model for Large Eddy Simulation of the
incompressible magnetohydrodynamic (MHD) equations based on the Eddy Damped
Quasi Normal Markovian approximation. This model extends classical spectral
Large Eddy Simulations for the Navier-Stokes equations to incorporate general
(non Kolmogorovian) spectra as well as eddy noise. We derive the model for MHD
and show that introducing a new eddy-damping time for the dynamics of spectral
tensors in the absence of equipartition between the velocity and magnetic
fields leads to better agreement with direct numerical simulations, an
important point for dynamo computations. | 0803.4499v1 |
2008-04-10 | Trapped Phase-Segregated Bose-Fermi Mixtures and their Collective Excitations | Recent progress in the field of ultracold gases has allowed the creation of
phase-segregated Bose-Fermi systems. We present a theoretical study of their
collective excitations at zero temperature. As the fraction of fermion to boson
particle number increases, the collective mode frequencies take values between
those for a fully bosonic and those for a fully fermionic cloud, with damping
in the intermediate region. This damping is caused by fermions which are
resonantly driven at the interface. | 0804.1759v2 |
2008-04-14 | Size dependence of multipolar plasmon resonance frequencies and damping rates in simple metal spherical nanoparticles | Multipolar plasmon oscillation frequencies and corresponding damping rates
for nanospheres formed of the simplest free-electron metals are studied. The
possibility of controlling plasmon features by choosing the size and dielectric
properties of the sphere surroundings is discussed. Optical properties of the
studied metals are described within the Drude-Sommerfeld model of the
dielectric function with effective parameters acounting for the contribution of
conduction electrons and of interband transitions. No approximation is made in
respect of the size of a particle; plasmon size characteristics are described
rigorously. The results of our experiment on sodium nanodroplets [1] are
compared with the oscillation frequency size dependence of dipole and
quadrupole plasmon. | 0804.2156v1 |
2008-06-05 | Thermally Assisted Spin Hall Effect | The spin polarized charge transport is systematically analyzed as a thermally
driven stochastic process. The approach is based on Kramers' equation
describing the semiclassical motion under the inclusion of stochastic and
damping forces. Due to the relativistic spin-orbit coupling the damping
experiences a relativistic correction leading to an additional contribution
within the spin Hall conductivity. A further contribution to the conductivity
is originated from the averaged underlying crystal potential, the mean value of
which depends significantly on the electric field. We derive an exact
expression for the electrical conductivity. All corrections are estimated in
lowest order of a relativistic approach and in the linear response regime. | 0806.0948v1 |
2008-06-13 | General Solution of the Quantum Damped Harmonic Oscillator II : Some Examples | In the preceding paper (arXiv : 0710.2724 [quant-ph]) we have constructed the
general solution for the master equation of quantum damped harmonic oscillator,
which is given by the complicated infinite series in the operator algebra
level. In this paper we give the explicit and compact forms to solutions
(density operators) for some initial values. In particular, the compact one for
the initial value based on a coherent state is given, which has not been given
as far as we know. Moreover, some related problems are presented. | 0806.2169v1 |
2008-08-27 | Entanglement dynamics of two-qubit system in different types of noisy channels | In this paper, we study entanglement dynamics of a two-qubit extended
Werner-like state locally interacting with independent noisy channels, i.e.,
amplitude damping, phase damping and depolarizing channels. We show that the
purity of initial entangled state has direct impacts on the entanglement
robustness in each noisy channel. That is, if the initial entangled state is
prepared in mixed instead of pure form, the state may exhibit entanglement
sudden death (ESD) and/or be decreased for the critical probability at which
the entanglement disappear. | 0808.3690v1 |
2008-09-01 | Heatons induced by attosecond laser pulses | In this paper the dynamics of the interaction of attosecond laser pulses with
matter is investigated. It will be shown that the master equation: modified
Klein-Gordon equation describes the propagation of the heatons. Heatons are the
thermal wave packets. When the duration of the laser pulses is of the order of
attosecond the heaton thermal wave packets are nondispersive objects. For
infinite time the heatons are damped with damping factor of the order of
relaxation time for thermal processes. | 0809.0204v1 |
2008-10-09 | Heat conduction in 2D strongly-coupled dusty plasmas | We perform non-equilibrium simulations to study heat conduction in
two-dimensional strongly coupled dusty plasmas. Temperature gradients are
established by heating one part of the otherwise equilibrium system to a higher
temperature. Heat conductivity is measured directly from the stationary
temperature profile and heat flux. Particular attention is paid to the
influence of damping effect on the heat conduction. It is found that the heat
conductivity increases with the decrease of the damping rate, while its
magnitude agrees with previous experimental measurement. | 0810.1623v2 |
2008-10-21 | Structurally damped plate and wave equations with random point force in arbitrary space dimensions | In this paper we consider structurally damped plate and wave equations with
point and distributed random forces. In order to treat space dimensions more
than one, we work in the setting of $L^q$--spaces with (possibly small)
$q\in(1,2)$. We establish existence, uniqueness and regularity of mild and weak
solutions to the stochastic equations employing recent theory for stochastic
evolution equations in UMD Banach spaces. | 0810.3898v2 |
2008-11-05 | Spectral function and quasi-particle damping of interacting bosons in two dimensions | We employ the functional renormalization group to study dynamical properties
of the two-dimensional Bose gas. Our approach is free of infrared divergences,
which plague the usual diagrammatic approaches, and is consistent with the
exact Nepomnyashchy identity, which states that the anomalous self-energy
vanishes at zero frequency and momentum. We recover the correct infrared
behavior of the propagators and present explicit results for the spectral
line-shape, from which we extract the quasi-particle dispersion and damping. | 0811.0624v2 |
2008-11-13 | Existence of weak solutions to the Cauchy problem of a semilinear wave equation with supercritical interior source and damping | In this paper we show existence of finite energy solutions for the Cauchy
problem associated with a semilinear wave equation with interior damping and
supercritical source terms. The main contribution consists in dealing with
super-supercritical source terms (terms of the order of $|u|^p$ with $p\geq 5$
in $n=3$ dimensions), an open and highly recognized problem in the literature
on nonlinear wave equations. | 0811.2151v1 |
2008-11-17 | Asymptotic stability and blow up for a semilinear damped wave equation with dynamic boundary conditions | In this paper we consider a multi-dimensional wave equation with dynamic
boundary conditions, related to the Kelvin-Voigt damping. Global existence and
asymptotic stability of solutions starting in a stable set are proved. Blow up
for solutions of the problem with linear dynamic boundary conditions with
initial data in the unstable set is also obtained. | 0811.2783v3 |
2008-11-19 | Weyl laws for partially open quantum maps | We study a toy model for "partially open" wave-mechanical system, like for
instance a dielectric micro-cavity, in the semiclassical limit where ray
dynamics is applicable. Our model is a quantized map on the 2-dimensional
torus, with an additional damping at each time step, resulting in a subunitary
propagator, or "damped quantum map". We obtain analogues of Weyl's laws for
such maps in the semiclassical limit, and draw some more precise estimates when
the classical dynamic is chaotic. | 0811.3134v2 |
2008-12-16 | A picogram and nanometer scale photonic crystal opto-mechanical cavity | We describe the design, fabrication, and measurement of a cavity
opto-mechanical system consisting of two nanobeams of silicon nitride in the
near-field of each other, forming a so-called "zipper" cavity. A photonic
crystal patterning is applied to the nanobeams to localize optical and
mechanical energy to the same cubic-micron-scale volume. The picrogram-scale
mass of the structure, along with the strong per-photon optical gradient force,
results in a giant optical spring effect. In addition, a novel damping regime
is explored in which the small heat capacity of the zipper cavity results in
blue-detuned opto-mechanical damping. | 0812.2953v1 |
2009-02-03 | Freezing of spin dynamics in underdoped cuprates | The Mori's memory function approach to spin dynamics in doped
antiferromagnetic insulator combined with the assumption of temperature
independent static spin correlations and constant collective mode damping leads
to w/T scaling in a broad range. The theory involving a nonuniversal scaling
parameter is used to analyze recent inelastic neutron scattering results for
underdoped cuprates. Adopting modified damping function also the emerging
central peak in low-doped cuprates at low temperatures can be explained within
the same framework. | 0902.0546v1 |
2009-02-12 | Discrete breathers in a forced-damped array of coupled pendula: Modeling, Computation and Experiment | In this work, we present a mechanical example of an experimental realization
of a stability reversal between on-site and inter-site centered localized
modes. A corresponding realization of a vanishing of the Peierls-Nabarro
barrier allows for an experimentally observed enhanced mobility of the
localized modes near the reversal point. These features are supported by
detailed numerical computations of the stability and mobility of the discrete
breathers in this system of forced and damped coupled pendula. Furthermore,
additional exotic features of the relevant model, such as dark breathers are
briefly discussed. | 0902.2129v1 |
2009-03-08 | Enhancement of transmission rates in quantum memory channels with damping | We consider the transfer of quantum information down a single-mode quantum
transmission line. Such quantum channel is modeled as a damped harmonic
oscillator, the interaction between the information carriers -a train of N
qubits- and the oscillator being of the Jaynes-Cummings kind. Memory effects
appear if the state of the oscillator is not reset after each channel use. We
show that the setup without resetting is convenient in order to increase the
transmission rates, both for the transfer of quantum and classical private
information. Our results can be applied to the micromaser. | 0903.1424v1 |
2009-03-15 | A variational approach to strongly damped wave equations | We discuss a Hilbert space method that allows to prove analytical
well-posedness of a class of linear strongly damped wave equations. The main
technical tool is a perturbation lemma for sesquilinear forms, which seems to
be new. In most common linear cases we can furthermore apply a recent result
due to Crouzeix--Haase, thus extending several known results and obtaining
optimal analyticity angle. | 0903.2599v2 |
2009-03-30 | Damping of Exciton Rabi Rotations by Acoustic Phonons in Optically Excited InGaAs/GaAs Quantum Dots | We report experimental evidence identifying acoustic phonons as the principal
source of the excitation-induced-dephasing (EID) responsible for the intensity
damping of quantum dot excitonic Rabi rotations. The rate of EID is extracted
from temperature dependent Rabi rotation measurements of the ground-state
excitonic transition, and is found to be in close quantitative agreement with
an acoustic-phonon model. | 0903.5278v2 |
2009-05-13 | Landau damping | In this note we present the main results from the recent work
hal-00376547/arXiv:0904.2760, which for the first time establish Landau damping
in a nonlinear context. | 0905.2167v2 |
2009-05-13 | Amortissement Landau | Dans cette note nous pr\'esentons les principaux r\'esultats du r\'ecent
travail hal-00376547/arXiv:0904.2760, o\`u le ph\'enom\`ene d'amortissement
Landau est pour la premi\`ere fois \'etabli dans un contexte non lin\'eaire.
-----
In this note we present the main results from the recent work hal-00376547 /
arXiv:0904.2760, which for the first time establish Landau damping in a
nonlinear context. | 0905.2168v2 |
2009-06-27 | Effect of Bohm potential on a charged gas | Bohm's interpretation of Quantum Mechanics leads to the derivation of a
Quantum Kinetic Equation (QKE): in the present work, propagation of waves in
charged quantum gases is investigated starting from this QKE. Dispersion
relations are derived for fully and weakly degenerate fermions and bosons
(these latter above critical temperature), and the differences underlined. Use
of a kinetic equation permits investigation of "Landau-type" damping: it is
found that the presence of damping in fermion gases is dependent upon the
degree of degeneracy, whereas it is always present in boson gases. In fully
degenerate fermions a phenomenon appears that is akin to the "zero sound"
propagation. | 0906.5061v1 |
2009-07-14 | Quantum Monty Hall problem under decoherence | We study the effect of decoherence on quantum Monty Hall problem under the
influence of amplitude damping, depolarizing and dephasing channels. It is
shown that under the effect of decoherence, there is a Nash equilibrium of the
game in case of depolarizing channel for Alice's quantum strategy. Where as in
case of dephasing noise, the game is not influenced by the quantum channel. For
amplitude damping channel, the Bob's payoffs are found symmetrical with maximum
at p=0.5 against his classical strategy. However, it is worth-mentioning that
in case of depolarizing channel, Bob's classical strategy remains always
dominant against any choice of Alice's strategy. | 0907.2293v1 |
2009-08-31 | Rigorous Theory of Optical Trapping by an Optical Vortex Beam | We propose a rigorous theory for the optical trapping by optical vortices,
which is emerging as an important tool to trap mesoscopic particles. The common
perception is that the trapping is solely due to the gradient force, and may be
characterized by three real force constants. However, we show that the optical
vortex trap can exhibit complex force constants, implying that the trapping
must be stabilized by ambient damping. At different damping levels, particle
shows remarkably different dynamics, such as stable trapping, periodic and
aperiodic orbital motions. | 0908.4504v1 |
2009-09-11 | Energy decay for the damped wave equation under a pressure condition | We establish the presence of a spectral gap near the real axis for the damped
wave equation on a manifold with negative curvature. This results holds under a
dynamical condition expressed by the negativity of a topological pressure with
respect to the geodesic flow. As an application, we show an exponential decay
of the energy for all initial data sufficiently regular. This decay is governed
by the imaginary part of a finite number of eigenvalues close to the real axis. | 0909.2093v1 |
2009-09-12 | Signature of smooth transition from diabatic to adiabatic states in heavy-ion fusion reactions at deep subbarrier energies | We propose a novel extension of the standard coupled-channels framework for
heavy-ion reactions in order to analyze fusion reactions at deep subbarrier
incident energies. This extension simulates a smooth transition between the
diabatic two-body and the adiabatic one-body states. To this end, we damp
gradually the off-diagonal part of the coupling potential, for which the
position of the onset of the damping varies for each eigen channel. We show
that this model accounts well for the steep falloff of the fusion cross
sections for the $^{16}$O+$^{208}$Pb, $^{64}$Ni+$^{64}$Ni, and
$^{58}$Ni+$^{58}$Ni reactions. | 0909.2298v1 |
2009-10-14 | Plasmon-phonon Strongly-Coupled Mode in Epitaxial Graphene | We report the dispersion measurements, using angle-resolved reflection
electron-energy-loss-spectroscopy (AREELS), on two-dimensional (2D) plasmons in
single and multilayer graphene which couple strongly to surface optical phonon
(FK phonon) modes of silicon carbide substrate. The coupled modes show discrete
dispersion behaviors in the single and bilayer graphene. With increasing
graphene layers on SiC(0001), a transition from plasmon-like dispersion to
phonon-like dispersion is observed. For plasmon-like modes, the dispersion is
strongly damped by electron-hole pair excitations at entering single-particle
continuum, while phonon-like mode is undamped. In the region free of coupling,
the graphene 2D plasmon exhibits acoustic behavior with linear dispersion with
slope and damping determined by the Fermi surface topology. | 0910.2735v1 |
2009-10-23 | Collective Enhancement and Suppression of Excitation Decay in Optical Lattices | We calculate radiative lifetimes of collective electronic excitations of
atoms in an infinite one dimensional lattice. The translational symmetry along
the lattice restricts the photon wave vector component parallel to the lattice
to the exciton wave number and thus the possible emission directions. The
resulting radiation damping rate and emission pattern of the exciton strongly
deviates from independent atom. For some wave numbers and polarizations the
excitons superradiantly decay very fast, while other excitons show zero
radiation damping rate and form propagating meta-stable excitations. Such
states could be directly coupled via tailored evanescent fields from a nearby
fiber. | 0910.4501v1 |
2009-10-24 | Global Attractor for Weakly Damped Forced KdV Equation in Low Regularity on T | In this paper we consider the long time behavior of the weakly damped, forced
Korteweg-de Vries equation in the Sololev spaces of the negative indices in the
periodic case. We prove that the solutions are uniformly bounded in
$\dot{H}^s(\T)$ for $s>-\dfrac{1}{2}$. Moreover, we show that the solution-map
possesses a global attractor in $\dot{H}^s(\T)$ for $s>-\dfrac{1}{2}$, which is
a compact set in $H^{s+3}(\T)$. | 0910.4652v1 |
2009-10-24 | Two bodies gravitational system with variable mass and damping-antidamping effect due to star wind | We study two-bodies gravitational problem where the mass of one of the bodies
varies and suffers a damping-antidamping effect due to star wind during its
motion. A constant of motion, a Lagrangian and a Hamiltonian are given for the
radial motion of the system, and the period of the body is studied using the
constant of motion of the system. An application to the comet motion is given,
using the comet Halley as an example. | 0910.4684v2 |
2009-12-15 | Distillability sudden death in qutrit-qutrit systems under amplitude damping | Recently it has been discovered that certain two-qutrit entangled states
interacting with global and/or multi-local decoherence undergo distillability
sudden death (DSD). We investigate this phenomenon for qutrit-qutrit systems
interacting with statistically independent zero-temperature reservoirs. We show
that certain initially prepared free-entangled states become bound-entangled in
a finite time due to the action of Markovian dissipative environment. Moreover,
in contrast with local dephasing, simple local unitary transformations can
completely avoid distillability sudden death under amplitude damping. | 0912.2868v1 |
2009-12-15 | Global Controllability of Multidimensional Rigid Body by Few Torques | We study global controllability of 'rotating' multidimensional rigid body
(MRB) controlled by application of few torques. Study by methods of geometric
control requires analysis of algebraic structure introduced by the quadratic
term of Euler-Frahm equation. We discuss problems, which arise in the course of
this analysis, and establish several global controllability criteria for damped
and non damped cases. | 0912.2900v1 |
2010-02-05 | Damping Effect of Electromagnetic Radiation and Time-Dependent Schrodinger Equation | The inexactness of the time-dependent Schr\"odinger equation of a charged
particle in an external electromagnetic field is discussed in terms of the
damping effect of the radiation. A possible improvement is to add a nonlinear
term representing this effect to the linear Schr\"odinger equation. Conditions
for the nonlinear term are investigated and it is demonstrated that the
obtained nonlinear Schr\"odinger equation may present state evolutions similar
to the wave-function reduction and transitions between stationary states. | 1002.1116v3 |
2010-02-05 | Uniform stabilization in weighted Sobolev spaces for the KdV equation posed on the half-line | Studied here is the large-time behavior of solutions of the Korteweg-de Vries
equation posed on the right half-line under the effect of a localized damping.
Assuming as in \cite{linares-pazoto} that the damping is active on a set
$(a_0,+\infty)$ with $a_0>0$, we establish the exponential decay of the
solutions in the weighted spaces $L^2((x+1)^mdx)$ for $m\in \N ^*$ and
$L^2(e^{2bx}dx)$ for $b>0$ by a Lyapunov approach. The decay of the spatial
derivatives of the solution is also derived. | 1002.1127v1 |
2010-03-28 | Giant magnetic broadening of ferromagnetic resonance in a GMR Co/Ag/Co/Gd quadlayer | Both magnetic-resonance damping and the giant magnetoresistance effect have
been predicted to be strongly affected by the local density of states in thin
ferromagnetic films. We employ the antiferromagnetic coupling between Co and Gd
to provide a spontaneous change from parallel to antiparallel alignment of two
Co films. A sharp increase in magnetic damping accompanies the change from
parallel to antiparallel alignment, analogous to resistivity changes in giant
magnetoresistance. | 1003.5344v1 |
2010-04-04 | Quantum information reclaiming after amplitude damping | We investigate the quantum information reclaim from the environment after
amplitude damping has occurred. In particular we address the question of
optimal measurement on the environment to perform the best possible correction
on two and three dimensional quantum systems. Depending on the dimension we
show that the entanglement fidelity (the measure quantifying the correction
performance) is or is not the same for all possible measurements and uncover
the optimal measurement leading to the maximum entanglement fidelity. | 1004.0497v1 |
2010-04-09 | Validity of Landauer's principle in the quantum regime | We demonstrate the validity of Landauer's erasure principle in the strong
coupling quantum regime by treating the system-reservoir interaction in a
consistent way. We show that the initial coupling to the reservoir modifies
both energy and entropy of the system and provide explicit expressions for the
latter in the case of a damped quantum harmonic oscillator. These contributions
are related to the Hamiltonian of mean force and dominate in the strong damping
limit. They need therefore to be fully taken into account in any
low-temperature thermodynamic analysis of quantum systems. | 1004.1599v1 |
2010-04-22 | Critical exponent for damped wave equations with nonlinear memory | We consider the Cauchy problem in $\mathbb{R}^n,$ $n\geq 1,$ for a semilinear
damped wave equation with nonlinear memory. Global existence and asymptotic
behavior as $t\rightarrow\infty$ of small data solutions have been established
in the case when $1\leq n\leq3.$ Moreover, we derive a blow-up result under
some positive data in any dimensional space. | 1004.3850v4 |
2010-04-26 | Entanglement of a two-particle Gaussian state interacting with a heat bath | The effect of a thermal reservoir is investigated on a bipartite Gaussian
state. We derive a pre-Lindblad master equation in the non-rotating wave
approximation for the system. We then solve the master equation for a bipartite
harmonic oscillator Hamiltonian with entangled initial state. We show that for
strong damping the loss of entanglement is the same as for freely evolving
particles. However, if the damping is small, the entanglement is shown to
oscillate and eventually tend to a constant nonzero value. | 1004.4515v2 |
2010-04-27 | Radiation Damping in a Non-Abelian Strongly-Coupled Gauge Theory | We study a `dressed' or `composite' quark in strongly-coupled N=4
super-Yang-Mills (SYM), making use of the AdS/CFT correspondence. We show that
the standard string dynamics nicely captures the physics of the quark and its
surrounding quantum non-Abelian field configuration, making it possible to
derive a relativistic equation of motion that incorporates the effects of
radiation damping. From this equation one can deduce a non-standard dispersion
relation for the composite quark, as well as a Lorentz covariant formula for
its rate of radiation. | 1004.4912v1 |
2010-05-21 | Quantization of the Damped Harmonic Oscillator Revisited | We return to the description of the damped harmonic oscillator by means of a
closed quantum theory with a general assessment of previous works, in
particular the Bateman-Caldirola-Kanai model and a new model recently proposed
by one of the authors. We show the local equivalence between the two models and
argue that latter has better high energy behavior and is naturally connected to
existing open-quantum-systems approaches. | 1005.4096v1 |
2010-06-09 | Dispersion and damping of two-dimensional dust acoustic waves: Theory and Simulation | A two-dimensional generalized hydrodynamics (GH) model is developed to study
the full spectrum of both longitudinal and transverse dust acoustic waves (DAW)
in strongly coupled complex (dusty) plasmas, with memory-function-formalism
being implemented to enforce high-frequency sum rules. Results are compared
with earlier theories (such as quasi-localized charge approximation and its
extended version) and with a self-consistent Brownian dynamics simulation. It
is found that the GH approach provides good account, not only for dispersion
relations, but also for damping rates of the DAW modes in a wide range of
coupling strengths, an issue hitherto not fully addressed for dusty plasmas. | 1006.1799v1 |
2010-07-01 | Finite time extinction by nonlinear damping for Schrodinger equation | We consider the Schrodinger equation on a compact manifold, in the presence
of a nonlinear damping term, which is homogeneous and sublinear. For initial
data in the energy space, we construct a weak solution, defined for all
positive time, which is shown to be unique. In the one-dimensional case, we
show that it becomes zero in finite time. In the two and three-dimensional
cases, we prove the same result under the assumption of extra regularity on the
initial datum. | 1007.0077v2 |
2010-07-07 | Spin drag Hall effect in a rotating Bose mixture | We show that in a rotating two-component Bose mixture, the spin drag between
the two different spin species shows a Hall effect. This spin drag Hall effect
can be observed experimentally by studying the out-of-phase dipole mode of the
mixture. We determine the damping of this mode due to spin drag as a function
of temperature. We find that due to Bose stimulation there is a strong
enhancement of the damping for temperatures close to the critical temperature
for Bose-Einstein condensation. | 1007.1088v1 |
2010-08-30 | Synthesis of electrical networks interconnecting PZT actuators to damp mechanical vibrations | This paper proves that it is possible to damp mechanical vibrations of some
beam frames by means of piezoelectric actuators interconnected via passive
networks. We create a kind of electromechanical wave guide where the electrical
velocity group equals the mechanical one thus enabling an electromechanical
energy transfer. Numerical simulations are presented which prove the technical
feasibility of proposed device | 1008.5112v1 |
2010-09-15 | Anomalous High-Energy Spin Excitations in La2CuO4 | Inelastic neutron scattering is used to investigate the collective magnetic
excitations of the high-temperature superconductor parent antiferromagnet
La2CuO4. We find that while the lower energy excitations are well described by
spin-wave theory, including one- and two-magnon scattering processes, the
high-energy spin waves are strongly damped near the (1/2,0) position in
reciprocal space and merge into a momentum dependent continuum. This anomalous
damping indicates the decay of spin waves into other excitations, possibly
unbound spinon pairs. | 1009.2915v1 |
2010-10-05 | Damping of dHvA oscillations and vortex-lattice disorder in the peak-effect region of strong type-II superconductors | The phenomenon of magnetic quantum oscillations in the superconducting state
poses several questions that still defy satisfactory answers. A key
controversial issue concerns the additional damping observed in the vortex
state. Here, we show results of \mu SR, dHvA, and SQUID magnetization
measurements on borocarbide superconductors, indicating that a sharp drop
observed in the dHvA amplitude just below H_{c2} is correlated with enhanced
disorder of the vortex lattice in the peak-effect region, which significantly
enhances quasiparticle scattering by the pair potential. | 1010.0929v1 |
2010-10-21 | Classical behavior of strongly correlated Fermi systems near a quantum critical point. Transport properties | The low-temperature kinetics of the strongly correlated electron liquid
inhabiting a solid is analyzed. It is demonstrated that a softly damped branch
of transverse zero sound emerges when several bands cross the Fermi surface
simultaneously near a quantum critical point at which the density of states
diverges. Suppression of the damping of this branch occurs due to a mechanism
analogous to that affecting the phonon mode in solids at room temperature,
giving rise to a classical regime of transport at extremely low temperatures in
the strongly correlated Fermi system. | 1010.4547v1 |
2010-10-26 | Open Quantum Systems in Noninertial Frames | We study the effects of decoherence on the entanglement generated by Unruh
effect in noninertial frames by using bit flip, phase damping and depolarizing
channels. It is shown that decoherence strongly influences the initial state
entanglement. The entanglement sudden death can happens irrespective of the
acceleration of the noninertial frame under the action of phase flip and phase
damping channels. It is investigated that an early sudden death happens for
large acceleration under the depolarizing environment. Moreover, the
entanglement increases for a highly decohered phase flip channel. | 1010.5395v1 |
2010-11-17 | Faint Resonantly Scattered Lyman Alpha Emission from the Absorption Troughs of Damped Lyman Alpha Systems at z ~ 3 | We demonstrate that the Lyman alpha emission in the absorption troughs of a
large sample of stacked damped Lyman alpha absorption systems (DLAS) presented
by Rahmani et al (2010) is consistent with the spectral profiles and
luminosities of a recently detected population of faint Lyman alpha emitters at
z ~ 3. This result supports the suggestion that the faint emitters are to be
identified with the host galaxies of DLAS at these redshifts. | 1011.4061v1 |
2010-12-19 | Quantum damping of Fermi-Pasta-Ulam revivals in ultracold Bose gases | We propose an experimental scheme for studying the Fermi-Pasta-Ulam (FPU)
phenomenon in a quantum mechanical regime using ultracold atoms. Specifically,
we suggest and analyze a setup of one-dimensional Bose gases confined into an
optical lattice. The strength of quantum fluctuations is controlled by tuning
the number of atoms per lattice sites (filling factor). By simulating the
real-time dynamics of the Bose-Hubbard model by means of the exact numerical
method of time-evolving block decimation, we investigate the effects of quantum
fluctuations on the FPU recurrence and show that strong quantum fluctuations
cause significant damping of the FPU oscillation. | 1012.4159v1 |
2010-12-21 | Pullback attractors for a singularly nonautonomous plate equation | We consider the family of singularly nonautonomous plate equation with
structural damping \[ u_{tt} + a(t,x)u_{t} + (- \Delta) u_{t} + (-\Delta)^{2} u
+ \lambda u = f(u), \] in a bounded domain $\Omega \subset \R^n$, with Navier
boundary conditions. When the nonlinearity $f$ is dissipative we show that this
problem is globally well posed in $H^2_0(\Omega) \times L^2(\Omega)$ and has a
family of pullback attractors which is upper-semicontinuous under small
perturbations of the damping $a$. | 1012.4749v1 |
2010-12-30 | On rotational solutions for elliptically excited pendulum | The author considers the planar rotational motion of the mathematical
pendulum with its pivot oscillating both vertically and horizontally, so the
trajectory of the pivot is an ellipse close to a circle. The analysis is based
on the exact rotational solutions in the case of circular pivot trajectory and
zero gravity. The conditions for existence and stability of such solutions are
derived. Assuming that the amplitudes of excitations are not small while the
pivot trajectory has small ellipticity the approximate solutions are found both
for high and small linear damping. Comparison between approximate and numerical
solutions is made for different values of the damping parameter. | 1101.0062v1 |
2011-03-10 | Laser-like vibrational instability in rectifying molecular conductors | We study the damping of molecular vibrations due to electron-hole pair
excitations in donor-acceptor(D-A) type molecular rectifiers. At finite voltage
additional non-equilibrium electron-hole pair excitations involving both
electrodes become possible, and contribute to the stimulated emission and
absorption of phonons. We point out a generic mechanism for D-A molecules,
where the stimulated emission can dominate beyond a certain voltage due to
inverted position of the D and A quantum resonances. This leads to
current-driven amplification (negative damping) of the phonons similar to
laser-action. We investigate the effect in realistic molecular rectifier
structures using first principles calculations. | 1103.1990v1 |
2011-03-11 | Spin Transport in Polaronic and Superfluid Fermi Gases | We present measurements of spin transport in ultracold gases of fermionic
lithium-6 in a mixture of two spin states at a Feshbach resonance. In
particular, we study the spin dipole mode, where the two spin components are
displaced from each other against a harmonic restoring force. We prepare a
highly-imbalanced, or polaronic, spin mixture with a spin dipole excitation and
observe strong, unitarity limited damping of the spin dipole mode. In gases
with small spin imbalance, below the Pauli limit for superfluidity, we observe
strongly damped spin flow despite the presence of a superfluid core. | 1103.2337v1 |
2011-03-14 | Tidal Evolution of a Secularly Interacting Planetary System | In a multi-planet system, a gradual change in one planet's semi-major axis
will affect the eccentricities of all the planets, as angular momentum is
distributed via secular interactions. If tidal dissipation in the planet is the
cause of the change in semi-major axis, it also damps that planet's
eccentricity, which in turn also contributes to the evolution of all the
eccentricities. Formulae quantifying the combined effects on the whole system
due to semi-major axis changes, as well as eccentricity damping, are derived
here for a two-planet system. The CoRoT 7 system is considered as an example. | 1103.2794v1 |
2011-03-30 | Damping in quantum love affairs | In a series of recent papers we have used an operatorial technique to
describe stock markets and, in a different context, {\em love affairs} and
their time evolutions. The strategy proposed so far does not allow any dumping
effect. In this short note we show how, within the same framework, a strictly
non periodic or quasi-periodic effect can be introduced in the model by
describing in some details a linear Alice-Bob love relation with damping. | 1103.5907v1 |
2011-04-03 | Spatially confined Bloch oscillations in semiconductor superlattices | In a semiconductor superlattice with long scattering times, damping of Bloch
oscillations due to scattering is so small that convective nonlinearities may
compensate it and Bloch oscillations persist even in the hydrodynamic regime.
In this case, numerical solutions show that there are stable Bloch oscillations
confined to a region near the collector with inhomogeneous field, charge,
current density and energy density profiles. These Bloch oscillations disappear
when damping due to inelastic collisions becomes sufficiently strong. | 1104.0429v2 |
2011-04-06 | Relativistic magnetic reconnection at X-type neutral points | Relativistic effects in the oscillatory damping of magnetic disturbances near
two-dimensional X-points are investigated. By taking into account displacement
current, we study new features of extremely magnetized systems, in which the
Alfv\'en velocity is almost the speed of light. The frequencies of the
least-damped mode are calculated using linearized relativistic MHD equations
for wide ranges of the Lundquist number S and the magnetization parameter
$\sigma$. These timescales approach constant values in the large resistive
limit: the oscillation time becomes a few times the light crossing time,
irrespective of $\sigma$, and the decay time is proportional to $\sigma$ and
therefore is longer for a highly magnetized system. | 1104.1003v1 |
2011-04-06 | Observed damping of the slow magnetoacoustic mode | Spectroscopic and stereoscopic imaging observations of slow magnetoacoustic
wave propagation within a coronal loop are investigated to determine the decay
length scale of the slow magnetoacoustic mode in three dimensions and the
density profile within the loop system. The slow wave is found to have an
e-folding decay length scale of $20,000^{+4000}_{-3000}$km with a uniform
density profile along the loop base. These observations place quantitive
constraints on the modelling of wave propagation within coronal loops.
Theoretical forward modelling suggests that magnetic field line divergence is
the dominant damping factor and thermal conduction is insufficient, given the
observed parameters of the coronal loop temperature, density and wave mode
period. | 1104.1100v1 |
2011-04-17 | Stochastic Wave Equations with Nonlinear Damping and Source Terms | In this paper, we discuss an initial boundary value problem for the
stochastic wave equation involving the nonlinear damping term $|u_t|^{q-2}u_t$
and a source term of the type $|u|^{p-2}u$. We firstly establish the local
existence and uniqueness of solution by the Galerkin approximation method and
show that the solution is global for $q\geq p$. Secondly, by an appropriate
energy inequality, the local solution of the stochastic equations will blow up
with positive probability or explosive in energy sense for $p>q$. | 1104.3279v2 |
2011-05-07 | Cooperative scattering measurement of coherence in a spatially modulated Bose gas | Correlations of a Bose gas released from an optical lattice are measured
using superradiant scattering. Conditions are chosen so that after initial
incident light pumping at the Bragg angle for diffraction, due to matter wave
amplification and mode competition, superradiant scattering into the Bragg
diffracted mode is preponderant. A temporal analysis of the superradiant
scattering gain reveals periodical oscillations and damping due to the initial
lack of coherence between lattice sites. Such damping is used for
characterizing first order spatial correlations in our system with a precision
of one lattice period. | 1105.1425v1 |
2011-06-09 | Hamiltonian of mean force for damped quantum systems | We consider a quantum system linearly coupled to a reservoir of harmonic
oscillators. For finite coupling strengths, the stationary distribution of the
damped system is not of the Gibbs form, in contrast to standard thermodynamics.
With the help of the quantum Hamiltonian of mean force, we quantify this
deviation exactly for a harmonic oscillator and provide approximations in the
limit of high and low temperatures, and weak and strong couplings. Moreover, in
the semiclassical regime, we use the quantum Smoluchowski equation to obtain
results valid for any potential. We, finally, give a physical interpretation of
the deviation in terms of the initial system-reservoir coupling. | 1106.1775v1 |
2011-06-17 | Current effect on magnetization oscillations in a ferromagnet - antiferromagnet junction | Spin-polarized current effect is studied on the static and dynamic
magnetization of the antiferromagnet in a ferromagnet - antiferromagnet
junction. The macrospin approximation is generalized to antiferromagnets.
Canted antiferromagnetic configuration and resulting magnetic moment are
induced by an external magnetic field. The resonance frequency and damping are
calculated, as well as the threshold current density corresponding to
instability appearance. A possibility is shown of generating low-damping
magnetization oscillations in terahertz range. The fluctuation effect is
discussed on the canted antiferromagnetic configuration. | 1106.3519v1 |
2011-06-23 | Dissipation evidence for the quantum damped harmonic oscillator via pseudo-bosons | It is known that a self-adjoint, time-independent hamiltonian can be defined
for the quantum damped harmonic oscillator. We show here that the two vacua
naturally associated to this operator, when expressed in terms of
pseudo-bosonic lowering and raising operators, appear to be non
square-integrable. This fact is interpreted as the evidence of the dissipation
effect of the classical oscillator at a purely quantum level. | 1106.4638v1 |
2011-07-15 | Aspects of General Relativity: Pseudo-Finsler extensions, Quasi-normal frequencies and Multiplication of tensorial distributions | This thesis is based on three different projects, all of them are directly
linked to the classical general theory of relativity, but they might have
consequences for quantum gravity as well. The first chapter deals with
pseudo-Finsler geometric extensions of the classical theory, these being ways
of naturally representing high-energy Lorentz symmetry violations. The second
chapter deals with the problem of highly damped quasi-normal modes related to
different types of black hole spacetimes. Besides the astrophysical meaning of
the quasi-normal modes, there are conjectures about the link between the highly
damped modes and black hole thermodynamics. The third chapter is related to the
topic of multiplication of tensorial distributions. | 1107.2978v1 |
2011-08-08 | Synchrotron radiation damping, intrabeam scattering and beam-beam simulations for HE-LHC | The proposed High-Energy LHC project presents an unusual combination of
strong synchrotron radiation (SR) damping and intrabeam scattering (IBS), which
is not seen in present-day hadron colliders. The subject of investigation
reported in this paper was the simulation of beam-beam effect for the HE-LHC
parameters. Parameters of SR and IBS are calculated, and the luminosity
evolution is simulated in the absence of beambeam interaction. Then, a
weak-strong numerical simulation is used to predict the effect of beam-beam
interaction on particle losses and emittance evolution. | 1108.1644v1 |
2011-09-09 | Delocalization of slowly damped eigenmodes on Anosov manifolds | We look at the properties of high frequency eigenmodes for the damped wave
equation on a compact manifold with an Anosov geodesic flow. We study
eigenmodes with spectral parameters which are asymptotically close enough to
the real axis. We prove that such modes cannot be completely localized on
subsets satisfying a condition of negative topological pressure. As an
application, one can deduce the existence of a "strip" of logarithmic size
without eigenvalues below the real axis under this dynamical assumption on the
set of undamped trajectories. | 1109.1909v2 |
2011-10-18 | Life times and chirality of spin-waves in antiferromagnetic and ferromagnetic FeRh: time depedent density functional theory perspective | The study of the spin excitations in antiferromagnetic (AFM) and
ferromagnetic (FM) phases of FeRh is reported. We demonstrate that although the
Fe atomic moments are well defined there is a number of important phenomena
absent in the Heisenberg description: Landau damping of spin waves, large Rh
moments induced by the AFM magnons, the formation of the optical magnons
terminated by Stoner excitations. We relate the properties of the spin-wave
damping to the features of the Stoner continuum and compare the chirality of
the spin excitations in AFM, FM and paramagnetic (PM) systems. | 1110.3913v1 |
2011-10-21 | Environment-Assisted Error Correction of Single-Qubit Phase Damping | Open quantum system dynamics of random unitary type may in principle be fully
undone. Closely following the scheme of environment-assisted error correction
proposed by Gregoratti and Werner [M. Gregoratti and R. F. Werner, J. Mod. Opt.
50(6), 915-933 (2003)], we explicitly carry out all steps needed to invert a
phase-damping error on a single qubit. Furthermore, we extend the scheme to a
mixed-state environment. Surprisingly, we find cases for which the uncorrected
state is closer to the desired state than any of the corrected ones. | 1110.4806v1 |
2011-11-01 | Damping of tensor modes in inflation | We discuss the damping of tensor modes due to anisotropic stress in
inflation. The effect is negligible in standard inflation and may be
significantly large in inflation models that involve drastic production of
free-streaming particles. | 1111.0295v3 |
2011-11-04 | Global uniform asymptotic stabilization and k-exponential trajectory tracking of underactuated surface ships with non-diagonal inertia/damping matrices | In this work, we investigate the state stabilization and trajectory tracking
problems of underactuated surface ships with full state model of having
non-diagonal inertia and damping matrices. By combining the novel state
transformations, the direct Lyapunov approach, and the nonlinear time-varying
tools, the stabilization and the trajectory tracking controllers are developed
respectively guaranteeing global uniform asymptotic convergence of the state to
the desired set point and global exponential convergence to the desired
reference trajectory via mild persistent exciting conditions. Simulation
examples are given to illustrate the effectiveness of the proposed control
schemes. | 1111.1029v1 |
2011-11-08 | The entropy of large black holes in loop quantum gravity: A combinatorics/analysis approach | The issue of a possible damping of the entropy periodicity for large black
holes in Loop Quantum Gravity is highly debated. Using a combinatorics/analysis
approach, we give strong arguments in favor of this damping, at least for
prescriptions where the projection constraint is not fully implemented. This
means that black holes in loop gravity exhibit an asymptotic Bekenstein-Hawking
behavior, provided that a consistent choice of the Immirzi constant is made. | 1111.1975v1 |
2011-11-15 | Finite Size Effects of the Surface States in a Lattice Model of Topological Insulator | Energy gap and wave function in thin films of topological insulator is
studied, based on tight--binding model. It is revealed that thickness
dependence of the magnitude of energy gap is composed of damping and
oscillation. The damped behavior originates from the presence of gapless
surface Dirac cone in the infinite thickness limit. On the other hand, the
oscillatory behavior stems from electronic properties in the thin thickness
limit. | 1111.3528v2 |
2011-11-23 | Pumping the eccentricity of exoplanets by tidal effect | Planets close to their host stars are believed to undergo significant tidal
interactions, leading to a progressive damping of the orbital eccentricity.
Here we show that, when the orbit of the planet is excited by an outer
companion, tidal effects combined with gravitational interactions may give rise
to a secular increasing drift on the eccentricity. As long as this secular
drift counterbalances the damping effect, the eccentricity can increase to high
values. This mechanism may explain why some of the moderate close-in exoplanets
are observed with substantial eccentricity values. | 1111.5486v1 |
2011-11-30 | Shear viscosity and damping of collective modes in a two-dimensional Fermi gas | We compute the shear viscosity of a two dimensional Fermi gas interacting via
a short range potential with scattering length $a_{2d}$ in kinetic theory. We
find that kinetic theory predicts that the shear viscosity to entropy density
ratio of a strongly interacting two dimensional gas is comparable to that of
the three dimensional unitary gas. We use our results to compute the damping of
collective modes in a trapped Fermi gas, and compare to experimental data
recently obtained in E. Vogt et al., arXiv:1111.1173. | 1111.7242v2 |
2011-12-13 | Drastically suppressing the error of ballistic readout of qubits | The thermal jitter of transmission of magnetic flux quanta in long Josephson
junctions is studied. While for large-to-critical damping and small values of
bias current the physically obvious dependence of the jitter versus length
$\sigma\sim\sqrt{L}$ is confirmed, for small damping starting from the
experimentally relevant $\alpha=0.03$ and below strong deviation from
$\sigma\sim\sqrt{L}$ is observed, up to nearly complete independence of the
jitter versus length, which is exciting from fundamental point of view, but
also intriguing from the point of view of possible applications. | 1112.2805v1 |
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