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2021-12-21 | ISS-Based Robustness to Various Neglected Damping Mechanisms for the 1-D Wave PDE | This paper is devoted to the study of the robustness properties of the 1-D
wave equation for an elastic vibrating string under four different damping
mechanisms that are usually neglected in the study of the wave equation: (i)
friction with the surrounding medium of the string (or viscous damping), (ii)
thermoelastic phenomena (or thermal damping), (iii) internal friction of the
string (or Kelvin-Voigt damping), and (iv) friction at the free end of the
string (the so-called passive damper). The passive damper is also the simplest
boundary feedback law that guarantees exponential stability for the string. We
study robustness with respect to distributed inputs and boundary disturbances
in the context of Input-to-State Stability (ISS). By constructing appropriate
ISS Lyapunov functionals, we prove the ISS property expressed in various
spatial norms. | 2112.11287v1 |
2022-01-20 | Derivation of the linear Boltzmann equation from the damped quantum Lorentz gas with a general scatterer configuration | It is a fundamental problem in mathematical physics to derive macroscopic
transport equations from microscopic models. In this paper we derive the linear
Boltzmann equation in the low-density limit of a damped quantum Lorentz gas for
a large class of deterministic and random scatterer configurations. Previously
this result was known only for the single-scatterer problem on the flat torus,
and for uniformly random scatterer configurations where no damping is required.
The damping is critical in establishing convergence -- in the absence of
damping the limiting behaviour depends on the exact configuration under
consideration, and indeed, the linear Boltzmann equation is not expected to
appear for periodic and other highly ordered configurations. | 2201.08229v2 |
2022-01-22 | Effect of MagneticField on the Damping Behavior of a Ferrofluid based Damper | This paper is an extension of our earlier work where we had reported a proof
of concept for a ferrofluid based damper. The damper used ferrofluid as damping
medium and it was seen that damping efficiency of the damper changes on
application of magnetic field. The present paper deals with a systematic study
of the effect of magnetic field on the damping efficiency of the damper.
Results of these studies are reported. It is seen that damping ratio varies
linearly with magnetic field ({\zeta} / H = 0.028 per kG) for magnetic field in
range of 0.0 to 4.5 kG. It may be mentioned that ferrofluid is different from
magnetorheological fluid even though both of them are magnetic field-responsive
fluids. The ferrofluid-dampers are better suited than MR Fluid-dampers for
their use in automobiles. | 2201.09027v1 |
2022-01-28 | Machine learning-based method of calorimeter saturation correction for helium flux analysis with DAMPE experiment | DAMPE is a space-borne experiment for the measurement of the cosmic-ray
fluxes at energies up to around 100 TeV per nucleon. At energies above several
tens of TeV, the electronics of DAMPE calorimeter would saturate, leaving
certain bars with no energy recorded. In the present work we discuss the
application of machine learning techniques for the treatment of DAMPE data, to
compensate the calorimeter energy lost by saturation. | 2201.12185v3 |
2022-04-01 | On the Importance of High-Frequency Damping in High-Order Conservative Finite-Difference Schemes for Viscous Fluxes | This paper discusses the importance of high-frequency damping in high-order
conservative finite-difference schemes for viscous terms in the Navier-Stokes
equations. Investigating nonlinear instability encountered in a high-resolution
viscous shock-tube simulation, we have discovered that a modification to the
viscous scheme rather than the inviscid scheme resolves a problem with spurious
oscillations around shocks. The modification introduces a term responsible for
high-frequency damping that is missing in a conservative high-order viscous
scheme. The importance of damping has been known for schemes designed for
unstructured grids. However, it has not been recognized well in very high-order
difference schemes, especially in conservative difference schemes. Here, we
discuss how it is easily missed in a conservative scheme and how to improve
such schemes by a suitably designed damping term. | 2204.00393v1 |
2022-06-20 | Stability and Damping in the Disks of Massive Galaxies | After their initial formation, disk galaxies are observed to be rotationally
stable over periods of >6 Gyr, implying that any large velocity disturbances of
stars and gas clouds are damped rapidly on the timescale of their rotation.
However, it is also known that despite this damping, there must be a degree of
random local motion to stabilize the orbits against degenerate collapse. A
mechanism for such damping is proposed by a combination of inter-stellar
gravitational interactions, and interactions with the Oort clouds and exo-Oort
objects associated with each star. Analysis of the gravitational interactions
between two stars is a three-body problem, because the stars are also in orbit
round the large virtual mass of the galaxy. These mechanisms may produce rapid
damping of large perturbations within a time period that is short on the scale
of observational look-back time, but long on the scale of the disk rotational
period for stars with small perturbations. This mechanism may also account for
the locally observed mean perturbations in the Milky Way of 8-15~km/s for
younger stars and 20-30~km/s for older stars. | 2206.09671v2 |
2022-09-15 | Superfluid $^4$He as a rigorous test bench for different damping models in nanoelectromechanical resonators | We have used nanoelectromechanical resonators to probe superfluid $^4$He at
different temperature regimes, spanning over four orders of magnitude in
damping. These regimes are characterized by the mechanisms which provide the
dominant contributions to damping and the shift of the resonance frequency:
tunneling two level systems at the lowest temperatures, ballistic phonons and
rotons at few hundred mK, and laminar drag in the two-fluid regime below the
superfluid transition temperature as well as in the normal fluid. Immersing the
nanoelectromechanical resonators in fluid increases their effective mass
substantially, decreasing their resonance frequency. Dissipationless superflow
gives rise to a unique possibility to dramatically change the mechanical
resonance frequency in situ, allowing rigorous tests on different damping
models in mechanical resonators. We apply this method to characterize tunneling
two-level system losses and magnetomotive damping in the devices. | 2209.07229v2 |
2022-11-08 | On the injection scale of the turbulence in the partially ionized very local interstellar medium | The cascade of magnetohydrodynamic (MHD) turbulence is subject to ion-neutral
collisional damping and neutral viscous damping in the partially ionized
interstellar medium. By examining the damping effects in the warm and partially
ionized local interstellar medium, we find that the interstellar turbulence is
damped by neutral viscosity at $\sim 261$ au and cannot account for the
turbulent magnetic fluctuations detected by Voyager 1 and 2. The MHD turbulence
measured by Voyager in the very local interstellar medium (VLISM) should be
locally injected in the regime where ions are decoupled from neutrals for its
cascade to survive the damping effects. With the imposed ion-neutral decoupling
condition, and the strong turbulence condition for the observed Kolmogorov
magnetic energy spectrum, we find that the turbulence in the VLISM is
sub-Alfv\'{e}nic, and its largest possible injection scale is $\sim 194$ au. | 2211.04496v1 |
2022-12-11 | The overtone level spacing of a black hole quasinormal frequencies: a fingerprint of a local $SL(2,\mathbb{R})$ symmetry | The imaginary part of the quasinormal frequencies spectrum for a static and
spherically symmetric black hole is analytically known to be equally spaced,
both for the highly damped and the weakly damped families of quasinormal modes.
Some interesting attempts have been made in the last twenty years to understand
in simple ways this level spacing for the only case of highly damped
quasinormal frequencies. Here, we show that the overtone level spacing, for
both the highly damped and weakly damped families of quasinormal modes, can
simply be understood as a fingerprint of a hidden local $SL(2,\mathbb{R})$
symmetry, near different regions of the black hole spacetime, i.e. the
near-horizon and the near-photon sphere regions. | 2212.05538v1 |
2022-12-15 | Formation of shifted shock for the 3D compressible Euler equations with time-dependent damping | In this paper, we show the shock formation to the compressible Euler
equations with time-dependent damping $\frac{a\p u}{(1+t)^{\lam}}$ in three
spatial dimensions without any symmetry conditions. It's well-known that for
$\lam>1$, the damping is too weak to prevent the shock formation for suitably
large data. However, the classical results only showed the finite existence of
the solution. Follow the work by D.Christodoulou in\cite{christodoulou2007},
starting from the initial isentropic and irrotational short pulse data, we show
the formation of shock is characterized by the collapse of the characteristic
hypersurfaces and the vanishing of the inverse foliation density function
$\mu$, at which the first derivatives of the velocity and the density blow up,
and the lifespan $T_{\ast}(a,\lam)$ is exponentially large. Moreover, the
damping effect will shift the time of shock formation $T_{\ast}$. The methods
in the paper can also be extended to the Euler equations with general
time-decay damping. | 2212.07828v1 |
2023-01-15 | Damped-driven system of bouncing droplets leading to deterministic diffusive behavior | Damped-driven systems are ubiquitous in science, however the damping and
driving mechanisms are often quite convoluted. This manuscript presents an
experimental and theoretical investigation of a fluidic droplet on a vertically
vibrating fluid bath as a damped-driven system. We study a fluidic droplet in
an annular cavity with the fluid bath forced above the Faraday wave threshold.
We model the droplet as a kinematic point particle in air and as inelastic
collisions during impact with the bath. In both experiments and the model the
droplet is observed to chaotically change velocity with a Gaussian
distribution. Finally, the statistical distributions from experiments and
theory are analyzed. Incredibly, this simple deterministic interaction of
damping and driving of the droplet leads to more complex Brownian-like and
Levy-like behavior. | 2301.06041v2 |
2023-03-01 | Generation of intraparticle quantum correlations in amplitude damping channel and its robustness | Quantum correlations between two or more different degrees of freedom of the
same particle is sometimes referred to as intraparticle entanglement. In this
work, we study these intra-particle correlations between two different degrees
of freedom under various decoherence channels viz. amplitude damping,
depolarising and phase damping channels. We observe a unique feature of the
amplitude damping channel, wherein entanglement is shown to arise starting from
separable states. In case of non maximally entangled input states, in addition
to entanglement sudden death, the creation of entanglement is also observed,
having an asymptotic decay over a long time. These counter-intuitive behaviours
arise due to the subtle interplay of channel and input state parameters, and
are not seen for interparticle entanglement without consideration of
non-Markovian noise. It is also not observed for maximally entangled input
states. Furthermore, investigation of entanglement evolution in phase damping
and depolarizing channels shows its robustness against decoherence as compared
to interparticle entanglement. | 2303.01238v1 |
2023-03-16 | Quantum Brownian Motion in the Caldeira-Leggett Model with a Damped Environment | We model a quantum system coupled to an environment of damped harmonic
oscillators by following the approach of Caldeira-Leggett and adopting the
Caldirola-Kanai Lagrangian for the bath oscillators. In deriving the master
equation of the quantum system of interest (a particle in a general potential),
we show that the potential is modified non-trivially by a new inverted harmonic
oscillator term, induced by the damping of the bath oscillators. We analyze
numerically the case of a particle in a double-well potential, and find that
this modification changes both the rate of decoherence at short times and the
well-transfer probability at longer times. We also identify a simple rescaling
condition that keeps the potential fixed despite changes in the environmental
damping. Here, the increase of environmental damping leads to a slowing of
decoherence. | 2303.09516v1 |
2023-03-22 | A Numerical Study of Landau Damping with PETSc-PIC | We present a study of the standard plasma physics test, Landau damping, using
the Particle-In-Cell (PIC) algorithm. The Landau damping phenomenon consists of
the damping of small oscillations in plasmas without collisions. In the PIC
method, a hybrid discretization is constructed with a grid of finitely
supported basis functions to represent the electric, magnetic and/or
gravitational fields, and a distribution of delta functions to represent the
particle field. Approximations to the dispersion relation are found to be
inadequate in accurately calculating values for the electric field frequency
and damping rate when parameters of the physical system, such as the plasma
frequency or thermal velocity, are varied. We present a full derivation and
numerical solution for the dispersion relation, and verify the PETSC-PIC
numerical solutions to the Vlasov-Poisson for a large range of wave numbers and
charge densities. | 2303.12620v1 |
2023-04-07 | Shifted shock formation for the 3D compressible Euler equations with damping and variation of the vorticity | In this paper, we consider the shock formation problem for the
3-dimensional(3D) compressible Euler equations with damping inspired by the
work \cite{BSV3Dfulleuler}. It will be shown that for a class of large data,
the damping can not prevent the formation of point shock, and the damping
effect shifts the shock time and the wave amplitude while the shock location
and the blow up direction remain the same with the information of this point
shock being computed explicitly. Moreover, the vorticity is concentrated in the
non-blow-up direction, which varies exponentially due to the damping effect.
Our proof is based on the estimates for the modulated self-similar variables
and lower bounds for the Lagrangian trajectories. | 2304.03506v2 |
2023-07-05 | Bayesian evidence for two slow-wave damping models in hot coronal loops | We compute the evidence in favour of two models, one based on field-aligned
thermal conduction alone and another that includes thermal misbalance as well,
in explaining the damping of slow magneto-acoustic waves in hot coronal loops.
Our analysis is based on the computation of the marginal likelihood and the
Bayes factor for the two damping models. We quantify their merit in explaining
the apparent relationship between slow mode periods and damping times, measured
with SOHO/SUMER in a set of hot coronal loops. The results indicate evidence in
favour of the model with thermal misbalance in the majority of the sample, with
a small population of loops for which thermal conduction alone is more
plausible. The apparent possibility of two different regimes of slow-wave
damping, if due to differences between the loops of host active regions and/or
the photospheric dynamics, may help with revealing the coronal heating
mechanism. | 2307.02439v1 |
2023-07-24 | From characteristic functions to multivariate distribution functions and European option prices by the damped COS method | We provide a unified framework for the computation of the distribution
function and the computation of prices of financial options from the
characteristic function of some density by the COS method. The classical COS
method is numerically very efficient in one-dimension but cannot deal very well
with certain financial options in general dimensions. Therefore, we introduce
the damped COS method which can handle a large class of integrands very
efficiently. We prove the convergence of the (damped) COS method and study its
order of convergence. The (damped) COS method converges exponentially if the
characteristic function decays exponentially. To apply the (damped) COS method,
one has to specify two parameters: a truncation range for the multivariate
density and the number of terms to approximate the truncated density by a
cosine series. We provide an explicit formula for the truncation range and an
implicit formula for the number of terms. Numerical experiments up to five
dimensions confirm the theoretical results. | 2307.12843v6 |
2023-07-26 | A Nonlinear Damped Metamaterial: Wideband Attenuation with Nonlinear Bandgap and Modal Dissipation | In this paper, we incorporate the effect of nonlinear damping with the
concept of locally resonant metamaterials to enable vibration attenuation
beyond the conventional bandgap range. The proposed design combines a linear
host cantilever beam and periodically distributed inertia amplifiers as
nonlinear local resonators. The geometric nonlinearity induced by the inertia
amplifiers causes an amplitude-dependent nonlinear damping effect. Through the
implementation of both modal superposition and numerical harmonic methods the
finite nonlinear metamaterial is accurately modelled. The resulting nonlinear
frequency response reveals the bandgap is both amplitude-dependent and
broadened. Furthermore, the modal frequencies are also attenuated due to the
nonlinear damping effect. The theoretical results are validated experimentally.
By embedding the nonlinear damping effect into locally resonant metamaterials,
wideband attenuation of the proposed metamaterial is achieved, which opens new
possibilities for versatile metamaterials beyond the limit of their linear
counterparts. | 2307.14165v2 |
2023-09-22 | Long time energy averages and a lower resolvent estimate for damped waves | We consider the damped wave equation on a compact manifold. We propose
different ways of measuring decay of the energy (time averages of lower energy
levels, decay for frequency localized data...) and exhibit links with resolvent
estimates on the imaginary axis. As an application we prove a universal
logarithmic lower resolvent bound on the imaginary axis for the damped wave
operator when the Geometric Control Condition (GCC) is not satisfied. This is
to be compared to the uniform boundedness of the resolvent on that set when GCC
holds. The proofs rely on (i) various (re-)formulations of the damped wave
equation as a conservative hyperbolic part perturbed by a lower order damping
term;(ii) a "Plancherel-in-time" argument as in classical proofs of the
Gearhart-Huang-Pr{\"u}ss theorem; and (iii) an idea of Bony-Burq-Ramond of
propagating a coherent state along an undamped trajectory up to Ehrenfest time. | 2309.12709v1 |
2023-12-12 | Coordination of Damping Controllers: A Data-Informed Approach for Adaptability | This work proposes a data-informed approach for an adaptable coordination of
damping controllers. The novel concept of coordination is based on minimizing
the Total Action, a single metric that measures the system's dynamic response
post-disturbance. This is a performance measure based on the physics of the
power system, which encapsulates the oscillation energy related to synchronous
generators. Deep learning theory is used to propose a Total Action function
approximator, which captures the relationship between the system wide-area
measurements, the status of damping controllers, and the conditions of the
disturbance. By commissioning the switching status (on/off) of damping
controllers in real-time, the oscillation energy is reduced, enhancing the
power system stability. The concept is tested in the Western North America
Power System (wNAPS) and compared with a model-based approach for the
coordination of damping controllers. The data-informed coordination outperforms
the model-based approach, demonstrating exceptional adaptability and
performance to handle multi-modal events. The proposed scheme shows outstanding
reductions in low-frequency oscillations even under various operating
conditions, fault locations, and time delay considerations. | 2312.07739v1 |
2024-01-26 | Efficient Control of Magnetization Dynamics Via W/CuO$_\text{x}$ Interface | Magnetization dynamics, which determine the speed of magnetization switching
and spin information propagation, play a central role in modern spintronics.
Gaining its control will satisfy the different needs of various spintronic
devices. In this work, we demonstrate that the surface oxidized Cu
(CuO$_\text{x}$) can be employed for the tunability of magnetization dynamics
of ferromagnet (FM)/heavy metal (HM) bilayer system. The capping CuO$_\text{x}$
layer in CoFeB/W/CuO$_\text{x}$ trilayer reduces the magnetic damping value in
comparison with the CoFeB/W bilayer. The magnetic damping even becomes lower
than that of the CoFeB/CuO$_\text{x}$ by ~ 16% inferring the stabilization of
anti-damping phenomena. Further, the reduction in damping is accompanied by a
very small reduction in the spin pumping-induced output DC voltage in the
CoFeB/W/CuO$_\text{x}$ trilayer. The simultaneous observation of anti-damping
and spin-to-charge conversion can be attributed to the orbital Rashba effect
observed at the HM/CuO$_\text{x}$ interface. Our experimental findings
illustrate that the cost-effective CuO$_\text{x}$ can be employed as an
integral part of modern spintronics devices owing to its rich underneath
spin-orbital physics. | 2401.14708v1 |
2024-02-08 | The stability analysis based on viscous theory of Faraday waves in Hele-Shaw cells | The linear instability of Faraday waves in Hele-Shaw cells is investigated
with consideration of the viscosity of fluids after gap-averaging the governing
equations due to the damping from two lateral walls and the dynamic behavior of
contact angle. A new hydrodynamic model is thus derived and solved
semi-analytically. The contribution of viscosity to critical acceleration
amplitude is slight compared to other factors associated with dissipation, and
the potential flow theory is sufficient to describe onset based on the present
study, but the rotational component of velocity can change the timing of onset
largely, which paradoxically comes from the viscosity. The model degenerates
into a novel damped Mathieu equation if the viscosity is dropped with two
damping terms referring to the gap-averaged damping and dissipation from
dynamic contact angle, respectively. The former increases when the gap size
decreases, and the latter grows as frequency rises. When it comes to the
dispersion relation of Faraday waves, an unusual detuning emerges due to the
imaginary part of the gap-averaged damping. | 2402.05505v2 |
2024-02-09 | Damping of density oscillations from bulk viscosity in quark matter | We study the damping of density oscillations in the quark matter phase that
might occur in compact stars. To this end we compute the bulk viscosity and the
associated damping time in three-flavor quark matter, considering both
nonleptonic and semileptonic electroweak processes. We use two different
equations of state of quark matter, more precisely, the MIT bag model and
perturbative QCD, including the leading order corrections in the strong
coupling constant. We analyze the dependence of our results on the density,
temperature and value of strange quark mass in each case. We then find that the
maximum of the bulk viscosity is in the range of temperature from 0.01 to 0.1
MeV for frequencies around 1 kHz, while the associated minimal damping times of
the density oscillations at those temperatures might be in the range of few to
hundreds milliseconds. Our results suggest that bulk viscous damping might be
relevant in the post-merger phase after the collision of two neutron stars if
deconfined matter is achieved in the process. | 2402.06595v1 |
2013-09-02 | Nonstrict inequality for Schmidt coefficients of three-qubit states | Generalized Schmidt decomposition of pure three-qubit states has four
positive and one complex coefficients. In contrast to the bipartite case, they
are not arbitrary and the largest Schmidt coefficient restricts severely other
coefficients. We derive a nonstrict inequality between three-qubit Schmidt
coefficients, where the largest coefficient defines the least upper bound for
the three nondiagonal coefficients or, equivalently, the three nondiagonal
coefficients together define the greatest lower bound for the largest
coefficient. In addition, we show the existence of another inequality which
should establish an upper bound for the remaining Schmidt coefficient. | 1309.0399v3 |
2018-10-30 | Generalized Stability of Heisenberg Coefficients | Stembridge introduced the notion of stability for Kronecker triples which
generalize Murnaghan's classical stability result for Kronecker coefficients.
Sam and Snowden proved a conjecture of Stembridge concerning stable Kronecker
triple, and they also showed an analogous result for Littlewood--Richardson
coefficients. Heisenberg coefficients are Schur structure constants of the
Heisenberg product which generalize both Littlewood--Richardson coefficients
and Kronecker coefficients. We show that any stable triple for Kronecker
coefficients or Littlewood--Richardson coefficients also stabilizes Heisenberg
coefficients, and we classify the triples stabilizing Heisenberg coefficients.
We also follow Vallejo's idea of using matrix additivity to generate Heisenberg
stable triples. | 1810.12512v1 |
2003-08-05 | Reliability of Calderbank-Shor-Steane Codes and Security of Quantum Key Distribution | After Mayers (1996, 2001) gave a proof of the security of the
Bennett-Brassard 1984 (BB84) quantum key distribution protocol, Shor and
Preskill (2000) made a remarkable observation that a Calderbank-Shor-Steane
(CSS) code had been implicitly used in the BB84 protocol, and suggested its
security could be proven by bounding the fidelity, say F(n), of the
incorporated CSS code of length n in the form 1-F(n) <= exp[-n E+o(n)] for some
positive number E. This work presents such a number E=E(R) as a function of the
rate of a code R, and a threshold R' such that E(R)>0 whenever R < R', which is
larger than the achievable rate based on the Gilbert-Varshamov bound that is
essentially due to Shor and Preskill (2000). The codes in the present work are
robust against fluctuations of channel parameters, which fact is needed to
establish the security rigorously and was not proved for rates above the
Gilbert-Varshamov rate before in the literature. As a byproduct, the security
of a modified BB84 protocol against any joint (coherent) attacks is proved
quantitatively. | 0308029v6 |
2011-07-13 | (In-)Stability of Singular Equivariant Solutions to the Landau-Lifshitz-Gilbert Equation | In this paper we use formal asymptotic arguments to understand the stability
proper- ties of equivariant solutions to the Landau-Lifshitz-Gilbert model for
ferromagnets. We also analyze both the harmonic map heatflow and Schrodinger
map flow limit cases. All asymptotic results are verified by detailed numerical
experiments, as well as a robust topological argument. The key result of this
paper is that blowup solutions to these problems are co-dimension one and hence
both unstable and non-generic. Solutions permitted to deviate from radial
symmetry remain global for all time but may, for suitable initial data,
approach arbitrarily close to blowup. A careful asymptotic analysis of
solutions near blowup shows that finite-time blowup corresponds to a saddle
fixed point in a low dimensional dynamical system. Radial symmetry precludes
motion anywhere but on the stable manifold towards blowup. A similar scenario
emerges in the equivariant setting: blowup is unstable. To be more precise,
blowup is co-dimension one both within the equivariant symmetry class and in
the unrestricted class of initial data. The value of the parameter in the
Landau-Lifshitz-Gilbert equation plays a very subdued role in the analysis of
equivariant blowup, leading to identical blowup rates and spatial scales for
all parameter values. One notable exception is the angle between solution in
inner scale (which bubbles off) and outer scale (which remains), which does
depend on parameter values. Analyzing near-blowup solutions, we find that in
the inner scale these solution quickly rotate over an angle {\pi}. As a
consequence, for the blowup solution it is natural to consider a continuation
scenario after blowup where one immediately re-attaches a sphere (thus
restoring the energy lost in blowup), yet rotated over an angle {\pi}. This
continuation is natural since it leads to continuous dependence on initial
data. | 1107.2620v1 |
1996-09-10 | The Damping Tail of CMB Anisotropies | By decomposing the damping tail of CMB anisotropies into a series of transfer
functions representing individual physical effects, we provide ingredients that
will aid in the reconstruction of the cosmological model from small-scale CMB
anisotropy data. We accurately calibrate the model-independent effects of
diffusion and reionization damping which provide potentially the most robust
information on the background cosmology. Removing these effects, we uncover
model-dependent processes such as the acoustic peak modulation and
gravitational enhancement that can help distinguish between alternate models of
structure formation and provide windows into the evolution of fluctuations at
various stages in their growth. | 9609079v1 |
1997-09-16 | Lyman-alpha emission as a tool to study high redshift damped systems | We report a quantitative study of the escape of Lyman-alpha photons from an
inhomogeneous optically thick medium that mimics the structure of damped
Lyman-alpha absorbers. Modeling the optically thick disk with 3 components
(massive stars and HII regions, dust, and neutral hydrogen), we study the
resulting emission line profile that may arise near the extended damped
absorption profile. | 9709150v1 |
1997-10-17 | The chemical evolution of galaxies causing damped Ly$α$ absorption | We have compiled all available data on chemical abundances in damped Lyman
alpha absorption systems for comparison with results from our combined chemical
and spectrophotometric galaxy evolution models. Preliminary results from
chemically consistent calculations are in agreement with observations of damped
Ly$\alpha$ systems. | 9710193v1 |
1998-01-26 | Are Damped Lyman alpha Systems Rotating Disks ? | We report on high spectral resolution observations of five damped Lyman alpha
systems whose line velocity profiles and abundances are analyzed. By combining
these data with information from the literature, we study the kinematics of the
low and high ionization phases of damped systems and discuss the possibility
that part of the motions is due to rotation. | 9801243v1 |
2001-10-29 | Damping of inhomogeneities in neutralino dark matter | The lightest supersymmetric particle, most likely the neutralino, might
account for a large fraction of dark matter in the Universe. We show that the
primordial spectrum of density fluctuations in neutralino cold dark matter
(CDM) has a sharp cut-off due to two damping mechanisms: collisional damping
during the kinetic decoupling of the neutralinos at O(10 MeV) and free
streaming after last scattering of neutralinos. The cut-off in the primordial
spectrum defines a minimal mass for CDM objects in hierarchical structure
formation. For typical neutralino and sfermion masses the first gravitationally
bound neutralino clouds have masses above 10^(-6) M_\odot. | 0110601v1 |
2002-08-03 | Adiabatic Index of Dense Matter and Damping of Neutron Star Pulsations | The adiabatic index Gamma_1 for perturbations of dense matter is studied
under various physical conditions which can prevail in neutron star cores. The
dependence of Gamma_1 on the composition of matter (in particular, on the
presence of hyperons), on the stellar pulsation amplitude, and on the baryon
superfluidity is analyzed. Timescales of damping of stellar pulsations are
estimated at different compositions, temperatures, and pulsation amplitudes.
Damping of pulsations by bulk viscosity in the neutron-star cores can prevent
the stars to pulsate with relative amplitudes > (1-15)% (depending on the
composition of matter). | 0208078v1 |
2003-01-07 | Damping of Neutron Star Shear Modes by Superfluid Friction | The forced motion of superfluid vortices in shear oscillations of rotating
solid neutron star matter produces damping of the mode. A simple model of the
unpinning and repinning processes is described, with numerical calculations of
the consequent energy decay times. These are of the order of 1 s or more for
typical anomalous X-ray pulsars but become very short for the general
population of radio pulsars. The superfluid friction processes considered here
may also be significant for the damping of r-modes in rapidly rotating neutron
stars. | 0301112v1 |
2005-04-25 | Radiative Effect on Particle Acceleration via Relativistic Electromagnetic Expansion | The radiation damping effect on the diamagnetic relativistic pulse
accelerator (DRPA) is studied in two-and-half dimensional Particle-in-Cell
(PIC) simulation with magnetized electron-positron plasmas. Self-consistently
solved radiation damping force converts particle energy to radiation energy.
The DRPA is still robust with radiation, and the Lorentz factor of the most
high energy particles reach more than two thousand before they decouple from
the electromagnetic pulse. Resulted emitted power from the pulse front is lower
in the radiative case than the estimation from the non-radiative case due to
the radiation damping. The emitted radiation is strongly linearly polarized and
peaked within few degrees from the direction of Poynting flux. | 0504561v1 |
1999-05-06 | Collective and chaotic motion in self-bound many-body systems | We investigate the interplay of collective and chaotic motion in a classical
self-bound N-body system with two-body interactions. This system displays a
hierarchy of three well separated time scales that govern the onset of chaos,
damping of collective motion and equilibration. Comparison with a mean-field
problem shows that damping is mainly due to dephasing. The Lyapunov exponent,
damping and equilibration rates depend mildly on the system size N. | 9905007v2 |
1997-05-12 | Damping of Oscillations in Layer-by-Layer Growth | We present a theory for the damping of layer-by-layer growth oscillations in
molecular beam epitaxy. The surface becomes rough on distances larger than a
layer coherence length which is substantially larger than the diffusion length.
The damping time can be calculated by a comparison of the competing roughening
and smoothening mechanisms. The dependence on the growth conditions,
temperature and deposition rate, is characterized by a power law. The
theoretical results are confirmed by computer simulations. | 9705100v1 |
1999-09-17 | Thermoelastic Damping in Micro- and Nano-Mechanical Systems | The importance of thermoelastic damping as a fundamental dissipation
mechanism for small-scale mechanical resonators is evaluated in light of recent
efforts to design high-Q micrometer- and nanometer-scale electro-mechanical
systems (MEMS and NEMS). The equations of linear thermoelasticity are used to
give a simple derivation for thermoelastic damping of small flexural vibrations
in thin beams. It is shown that Zener's well-known approximation by a
Lorentzian with a single thermal relaxation time slightly deviates from the
exact expression. | 9909271v1 |
2000-10-01 | Super-Radiance and the Unstable Photon Oscillator | If the damping of a simple harmonic oscillator from a thermally random force
is sufficiently strong, then the oscillator may become unstable. For a photon
oscillator (radiatively damped by electric dipole moments), the instability
leads to a low temperature Hepp-Lieb-Preparata super-radiant phase transition.
The stable oscillator regime is described by the free energy of the
conventional Casimir effect. The unstable (strongly damped) oscillator has a
free energy corresponding to Dicke super-radiance. | 0010013v1 |
2001-08-07 | Non-damped Acoustic Plasmon and Superconductivity in Single Wall Carbon Nanotubes | We show that non-damped acoustic plasmons exist in single wall carbon
nanotubes (SWCNT) and propose that the non-damped acoustic plasmons may mediate
electron-electron attraction and result in superconductivity in the SWCNT. The
superconducting transition temperature Tc for the SWCNT (3,3) obtained by this
mechanism agrees with the recent experimental result (Z. K. Tang et al, Science
292, 2462(2001)). We also show that it is possible to get higher Tc up to 99 K
by doping the SWCNT (5,5). | 0108124v2 |
2001-12-16 | The Damping of the Bose-Condensate Oscillations in a Trap at Zero Temperature | We discuss an existence of the damping for the radial condensate oscillations
in a cylindric trap at zero temperature. The damping is a result of the
parametric resonance leading to energy transfer from the coherent condensate
oscillations to the longitudinal sound waves within a finite frequency
interval. The parametric resonance is due to the oscillations of the sound
velocity. The triggering amplitudes at zero temperature are associated with the
zero-point oscillations. | 0112292v1 |
2002-06-13 | Beliaev damping of quasi-particles in a Bose-Einstein condensate | We report a measurement of the suppression of collisions of quasi-particles
with ground state atoms within a Bose-Einstein condensate at low momentum.
These collisions correspond to Beliaev damping of the excitations, in the
previously unexplored regime of the continuous quasi-particle energy spectrum.
We use a hydrodynamic simulation of the expansion dynamics, with the Beliaev
damping cross-section, in order to confirm the assumptions of our analysis. | 0206234v1 |
2002-06-28 | Accidental suppression of Landau damping of the transverse breathing mode in elongated Bose-Einstein condensates | We study transverse radial oscillations of an elongated Bose-Einstein
condensate using finite temperature simulations, in the context of a recent
experiment at ENS. We demonstrate the existence of a mode corresponding to an
in-phase collective oscillation of both the condensate and thermal cloud.
Excitation of this mode accounts for the very small damping rate observed
experimentally, and we find excellent quantitative agreement between experiment
and theory. In contrast to other condensate modes, interatomic collisions are
found to be the dominant damping mechanism in this case. | 0206582v1 |
2005-03-03 | Collapse of thermal activation in moderately damped Josephson junctions | We study switching current statistics in different moderately damped
Josephson junctions: a paradoxical collapse of the thermal activation with
increasing temperature is reported and explained by interplay of two
conflicting consequences of thermal fluctuations, which can both assist in
premature escape and help in retrapping back into the stationary state. We
analyze the influence of dissipation on the thermal escape by tuning the
damping parameter with a gate voltage, magnetic field, temperature and an
in-situ capacitor. | 0503067v1 |
2006-03-13 | Universal features of the defect-induced damping of lattice vibrations | It is shown that any defect gives an Ohmic contribution to the damping of any
normal mode of the crystal lattice with nonzero wavevector which does not
vanish at zero temperature. This explains the large phason damping observed at
low temperatures in incommensurate phases, and might be a key factor to
understand the linear-in-$T$ specific heat observed in a number of real
dielectrics at low enough temperatures. | 0603343v2 |
2006-04-25 | Spin Precession and Avalanches | In many magnetic materials, spin dynamics at short times are dominated by
precessional motion as damping is relatively small. In the limit of no damping
and no thermal noise, we show that for a large enough initial instability, an
avalanche can transition to an ergodic phase where the state is equivalent to
one at finite temperature, often above that for ferromagnetic ordering. This
dynamical nucleation phenomenon is analyzed theoretically. For small finite
damping the high temperature growth front becomes spread out over a large
region. The implications for real materials are discussed. | 0604563v1 |
2007-02-11 | Non-Markovian coherence dynamics of driven spin boson model: damped quantum beat or large amplitude coherence oscillation | The dynamics of driven spin boson model is studied analytically by means of
the perturbation approach based on a unitary transformation. We gave the
analytical expression for the population difference and coherence of the two
level system. The results show that in the weak driven case, the population
difference present damped coherent oscillation (single or double frequency) and
the frequencies depend on the initial state. The coherence exhibit damped
oscillation with Rabi frequency. When driven field is strong enough, the
population difference exhibit undamped large-amplitude coherent oscillation.
The results easily return to the two extreme cases without dissipation or
without periodic driven. | 0702268v1 |
2006-05-01 | Stability and quasinormal modes of the massive scalar field around Kerr black holes | We find quasinormal spectrum of the massive scalar field in the background of
the Kerr black holes. We show that all found modes are damped under the
quasinormal modes boundary conditions when $\mu M$ is not large, thereby
implying stability of the massive scalar field. This complements the region of
stability determined by the Beyer inequality for large masses of the field. We
show that, similar to the case of a non-rotating black holes, the massive term
of the scalar field does not contribute in the regime of high damping. Thereby,
the high damping asymptotic should be the same as for the massless scalar
field. | 0605013v1 |
1992-04-06 | Comment on ``High Temperature Fermion Propagator -- Resummation and Gauge Dependence of the Damping Rate'' | Baier et al. have reported the damping rate of long-wavelength fermionic
excitations in high-temperature QED and QCD to be gauge-fixing-dependent even
within the resummation scheme due to Braaten and Pisarski. It is shown that
this problem is caused by the singular nature of the on-shell expansion of the
fermion self-energy in the infra-red. Its regularization reveals that the
alleged gauge dependence pertains to the residue rather than the pole of the
fermion propagator, so that in particular the damping constant comes out
gauge-independent, as it should. | 9204210v1 |
1993-02-09 | Damping rates for moving particles in hot QCD | Using a program of perturbative resummation I compute the damping rates for
fields at nonzero spatial momentum to leading order in weak coupling in hot
$QCD$. Sum rules for spectral densities are used to simplify the calculations.
For massless fields the damping rate has an apparent logarithmic divergence in
the infrared limit, which is cut off by the screening of static magnetic fields
(``magnetic mass''). This demonstrates how at high temperature even
perturbative quantities are sensitive to nonperturbative phenomenon. | 9302242v1 |
1994-04-21 | Is \lq\lq Heavy Quark Damping Rate Puzzle'' in Hot QCD Really the Puzzle? | Within the framework of perturbative resummation scheme of Pisarski and
Braaten, the decay- or damping-rate of a moving heavy quark (muon) to leading
order in weak coupling in hot QCD (QED) is examined. Although, as is well
known, the conventionally-defined damping rate diverges logarithmically at the
infrared limit, shown is that no such divergence appears in the physically
measurable decay rate. The cancellation occurs between the contribution from
the \lq\lq real'' decay diagram and the contribution from the diagrams with
\lq\lq thermal radiative correction''. | 9404318v1 |
1996-01-12 | Damping Rate of a Scalar Particle in Hot Scalar QED | In contrast to the damping of partons in a quark-gluon plasma, the damping of
a scalar particle in a hot scalar QED plasma can be calculated to leading order
for the whole momentum range using the Braaten-Pisarski method. In this way the
evolution of the logarithmic infrared singularity caused by the exchange of a
transverse photon from soft to hard momenta can be studied. | 9601254v1 |
1996-09-17 | Damping Rate of Quasiparticles in Degenerate Ultrarelativistic Plasmas | We compute the damping rate of a fermion in a dense relativistic plasma at
zero temperature. Just above the Fermi sea, the damping rate is dominated by
the exchange of soft magnetic photons (or gluons in QCD) and is proportional to
$(E-\mu)$, where E is the fermion energy and $\mu$ the chemical potential. We
also compute the contribution of soft electric photons and of hard photons. As
in the nonrelativistic case, the contribution of longitudinal photons is
proportional to $(E-\mu)^2$, and is thus non leading in the relativistic case. | 9609369v1 |
1997-05-28 | Classical Statistical Mechanics and Landau Damping | We study the retarded response function in scalar $\phi^4$-theory at finite
temperature. We find that in the high-temperature limit the imaginary part of
the self-energy is given by the classical theory to leading order in the
coupling. In particular the plasmon damping rate is a purely classical effect
to leading order, as shown by Aarts and Smit. The dominant contribution to
Landau damping is given by the propagation of classical fields in a heat bath
of non-interacting fields. | 9705452v1 |
1997-12-01 | A potential infrared problem with the damping rates for gluons with soft momentum in hot QCD | We calculate the damping rate $\gamma_l$ for longitudinal gluons with zero
momentum in finite high temperature QCD and show that some of its contributing
terms are infrared divergent. This is in contrast with the expectation that
this damping rate is to be equal to the corresponding one $\gamma_t$ for
transverse gluons which is known to be finite. Our calculation was motivated by
the fact that similar divergent terms occur when we calculated in a previous
work $\gamma_t$ to order $ p^2$, p being the momentum of the gluon. After we
present our results, we briefly discuss them. | 9712210v1 |
1998-04-21 | The Plasmon Damping Rate for T -> T_C | The plasmon damping rate in scalar field theory is computed close to the
critical temperature. It is shown that the divergent result obtained in
perturbation theory is a consequence of neglecting the thermal renormalization
of the coupling. Taking this effect into account, a vanishing damping rate is
obtained, leading to the critical slowing down of the equilibration process. | 9804351v2 |
1998-10-06 | Self-consistent Study on Color Transport in the Quark Gluon Plasma at Finite Chemical Potential | We calculate the relaxation time self-consistently to study the damping of
collective color modes and the color conductivity in a QGP by deriving
self-consistent equations for the damping rates of gluons and quarks to leading
order QCD by TFD including a chemical potential for quarks. We show that the
damping rates are not sensitive to the chemical potential whereas color
conductivity is enhanced considerably. | 9810256v1 |
1999-02-19 | The problem of nonlinear Landau damping in quark-gluon plasma | On the basis of the semiclassical equations for quark-gluon plasma (QGP) and
Yang-Mills equation, the generalized kinetic equation for waves with regard to
its interaction is obtained. The physical mechanisms defining nonlinear
scattering of a plasmon by QGP particles are analysed. The problem on a
connection of nonlinear Landau damping rate of longitudinal oscillation with
damping rate, obtained on the basis of hard thermal loops approximation, is
considered. | 9902397v2 |
1999-07-21 | A Slavnov-Taylor identity and equality of damping rates for static transverse and longitudinal gluons in hot QCD | A Slavnov-Taylor identity is derived for the gluon polarization tensor in hot
QCD. We evaluate its implications for damping of gluonic modes in the plasma.
Applying the identity to next to the leading order in hard-thermal-loop
resummed perturbation theory, we derive the expected equality of damping rates
for static transverse and longitudinal (soft) gluons. This is of interest also
in view of deviating recent reports of $\gamma_t(p=0)\neq\gamma_l(p=0)$ based
on a direct calculation of $\gamma_l(p=0)$. | 9907439v1 |
2000-09-15 | Fermion Damping Rate Effects in Cold Dense Matter | We review the non-Fermi or marginal liquid behavior of a relativistic QED
plasma. In this medium a quasiparticle has a damping rate that depends linearly
on the distance between its energy and the Fermi surface. We stress that this
dependence is due to the long-range character of the magnetic interactions in
the medium. Finally, we study how the quark damping rate modifies the gap
equation of color superconductivity, reducing the value of the gap at the Fermi
surface. | 0009182v1 |
2001-07-19 | Photon Damping Caused by Electron-Positron Pair Production in a Strong Magnetic Field | Damping of an electromagnetic wave in a strong magnetic field is analyzed in
the kinematic region near the threshold of electron-positron pair production.
Damping of the electromagnetic field is shown to be noticeably nonexponential
in this region. The resulting width of the photon $\gamma \to e^+ e^-$ decay is
considerably smaller than previously known results. | 0107217v1 |
2004-09-27 | Damping of electromagnetic waves due to electron-positron pair production | The problem of the backreaction during the process of electron-positron pair
production by a circularly polarized electromagnetic wave propagating in a
plasma is investigated. A model based on the relativistic Boltzmann-Vlasov
equation with a source term corresponding to the Schwinger formula for the pair
creation rate is used. The damping of the wave, the nonlinear up-shift of its
frequency due to the plasma density increase and the effect of the damping on
the wave polarization and on the background plasma acceleration are
investigated as a function of the wave amplitude. | 0409301v1 |
2005-10-25 | Infrared behavior of the dispersion relations in high-temperature scalar QED | We investigate the infrared properties of the next-to-leading-order
dispersion relations in scalar quantum electrodynamics at high temperature in
the context of hard-thermal-loop perturbation theory. Specifically, we
determine the damping rate and the energy for scalars with ultrasoft momenta.
We show by explicit calculations that an early external-momentum expansion,
before the Matsubara sum is performed, gives exactly the same result as a late
one. The damping rate is obtained up to fourth order included in the ultrasoft
momentum and the energy up to second order. The damping rate is found sensitive
in the infrared whereas the energy not. | 0510330v1 |
2006-11-09 | Lepton asymmetry in the primordial gravitational wave spectrum | Effects of neutrino free streaming is evaluated on the primordial spectrum of
gravitational radiation taking both neutrino chemical potential and masses into
account. The former or the lepton asymmetry induces two competitive effects,
namely, to increase anisotropic pressure, which damps the gravitational wave
more, and to delay the matter-radiation equality time, which reduces the
damping. The latter effect is more prominent and a large lepton asymmetry would
reduce the damping. We may thereby be able to measure the magnitude of lepton
asymmetry from the primordial gravitational wave spectrum. | 0611121v1 |
2005-03-17 | A New Approach to Canonical Quantization of the Radiation Damping | Inspired in some works about quantization of dissipative systems, in
particular of the damped harmonic oscillator\cite{MB,RB,12}, we consider the
dissipative system of a charge interacting with its own radiation, which
originates the radiation damping (RD). Using the indirect Lagrangian
representation we obtained a Lagrangian formalism with a Chern-Simons-like
term. A Hamiltonian analysis is also done, what leads to the quantization of
the system. | 0503135v1 |
2004-06-02 | Instability results for the damped wave equation in unbounded domains | We extend some previous results for the damped wave equation in bounded
domains in Euclidean spaces to the unbounded case. In particular, we show that
if the damping term is of the form $\alpha a$ with bounded $a$ taking on
negative values on a set of positive measure, then there will always exist
unbounded solutions for sufficiently large positive $\alpha$.
In order to prove these results, we generalize some existing results on the
asymptotic behaviour of eigencurves of one-parameter families of Schrodinger
operators to the unbounded case, which we believe to be of interest in their
own right. | 0406041v1 |
2002-12-11 | Rotational Damping and Compound Formation in Warm Rotating Nuclei | The rotational damping width \Gamma_{rot} and the compound damping width
\Gamma_{comp} are two fundamental quantities that characterize rapidly rotating
compound nuclei having finite thermal excitation energy. A two-component
structure in the strength function of consecutive E2 transitions reflects the
two widths, and it causes characteristic features in the double and triple
gamma-ray spectra. We discuss a new method to extract experimentally values of
\Gamma_{rot} and \Gamma_{comp}. The first preliminary result of this method is
presented. | 0212050v1 |
2003-07-27 | Chaos and rotational damping in particle-rotor model | The onset of chaos and the mechanism of rotational damping are studied in an
exactly soluble particle-rotor model. It is shown that the degree of chaoticity
as inferred from the statistical measures is closely related to the onset of
rotational damping obtained using the model Hamiltonian. | 0307104v2 |
1997-07-10 | Supersymmetric partner chirping of Newtonian free damping | We connect the classical free damping cases by means of Rosner's construction
in supersymmetric quantum mechanics. Starting with the critical damping, one
can obtain in the underdamping case a chirping of instantaneous physical
frequency \omega ^{2}(t) \propto \omega_{u}^{2}sech^2(\omega_{u}t), whereas in
the overdamped case the "chirping" is of the (unphysical) type \omega
^{2}(t)\propto\omega_{o}^{2}sec^{2}(\omega_{o}t), where \omega_{u}$ and
$\omega_{o} are the underdamped and overdamped frequency parameters,
respectively | 9707012v4 |
2000-04-10 | Ermakov-Lewis angles for one-parameter supersymmetric families of Newtonian free damping modes | We apply the Ermakov-Lewis procedure to the one-parameter damped modes
\tilde{y} recently introduced by Rosu and Reyes, which are related to the
common Newtonian free damping modes y by the general Riccati solution [H.C.
Rosu and M. Reyes, Phys. Rev. E 57, 4850 (1998), physics/9707019]. In
particular, we calculate and plot the angle quantities of this approach that
can help to distinguish these modes from the common y modes | 0004014v4 |
2002-10-29 | Model of Internal Friction Damping in Solids | A model for harmonic oscillator damping due to the internal friction of
solids has been developed, based on considerations of a long period pendulum.
The assumption of a complex elastic modulus to describe stress-strain
hysteresis in the support structure of the pendulum yields an expression for
the figure of merit Q that agrees with many experiments involving material
damping. As such, the approximations of this linear model stand in contrast
with common theory. | 0210121v1 |
2003-06-11 | Nonlinear Damping of the 'Linear' Pendulum | This study shows that typical pendulum dynamics is far from the simple
equation of motion presented in textbooks. A reasonably complete damping model
must use nonlinear terms in addition to the common linear viscous expression.
In some cases a nonlinear substitute for assumed linear damping may be more
appropriate. Even for exceptional cases where all nonlinearity may be ignored,
it is shown that viscous dissipation involves subtleties that can lead to huge
errors when ignored. | 0306081v1 |
2003-07-02 | Harmonic Oscillator Potential to describe Internal Dissipation | Assuming that a constant potential energy function has meaning for a
dissipated harmonic oscillator, then an important issue is the time dependence
of the turning points. Turning point studies demonstrate that the common model
of external (viscous) damping fails to properly describe those many systems
where structural (internal friction) damping is the most important source of
dissipation. For internal friction damping, the better model of potential
energy is one in which the function is not stationary. | 0307016v1 |
2004-08-19 | Beyond the Linear Damping Model for Mechanical Harmonic Oscillators | The steady state motion of a folded pendulum has been studied using
frequencies of drive that are mainly below the natural (resonance) frequency of
the instrument. Although the free-decay of this mechanical oscillator appears
textbook exponential, the steady state behavior of the instrument for
sub-resonance drive can be remarkably complex. Although the response cannot be
explained by linear damping models, the general features can be understood with
the nonlinear, modified Coulomb damping model developed by the author. | 0408091v1 |
1998-01-28 | Phenomenological damping in trapped atomic Bose-Einstein condensates | The method of phenomenological damping developed by Pitaevskii for
superfluidity near the $\lambda$ point is simulated numerically for the case of
a dilute, alkali, inhomogeneous Bose-condensed gas near absolute zero. We study
several features of this method in describing the damping of excitations in a
Bose-Einstein condensate. In addition, we show that the method may be employed
to obtain numerically accurate ground states for a variety of trap potentials. | 9801064v1 |
1998-04-06 | Optimal quantum codes for preventing collective amplitude damping | Collective decoherence is possible if the departure between quantum bits is
smaller than the effective wave length of the noise field. Collectivity in the
decoherence helps us to devise more efficient quantum codes. We present a class
of optimal quantum codes for preventing collective amplitude damping to a
reservoir at zero temperature. It is shown that two qubits are enough to
protect one bit quantum information, and approximately $L+ 1/2 \log_2((\pi
L)/2)$ qubits are enough to protect $L$ qubit information when $L$ is large.
For preventing collective amplitude damping, these codes are much more
efficient than the previously-discovered quantum error correcting or avoiding
codes. | 9804014v1 |
2000-01-12 | Antibunching effect of the radiation field in a microcavity with a mirror undergoing heavily damping oscillation | The interaction between the radiation field in a microcavity with a mirror
undergoing damping oscillation is investigated. Under the heavily damping
cases, the mirror variables are adiabatically eliminated.
The the stationary conditions of the system are discussed. The small
fluctuation approximation around steady values is applied to analysis the
antibunching effect of the cavity field. The antibunching condition is given
under two limit cases. | 0001036v1 |
2000-03-29 | Disagreement between correlations of quantum mechanics and stochastic electrodynamics in the damped parametric oscillator | Intracavity and external third order correlations in the damped nondegenerate
parametric oscillator are calculated for quantum mechanics and stochastic
electrodynamics (SED), a semiclassical theory. The two theories yield greatly
different results, with the correlations of quantum mechanics being cubic in
the system's nonlinear coupling constant and those of SED being linear in the
same constant. In particular, differences between the two theories are present
in at least a mesoscopic regime. They also exist when realistic damping is
included. Such differences illustrate distinctions between quantum mechanics
and a hidden variable theory for continuous variables. | 0003131v1 |
2002-02-15 | Decoherence of Quantum Damped Oscillators | Quantum dissipation is studied within two model oscillators, the
Caldirola-Kanai (CK) oscillator as an open system with one degree of freedom
and the Bateman-Feshbach-Tikochinsky (BFT) oscillator as a closed system with
two degrees of freedom. Though these oscillators describe the same classical
damped motion, the CK oscillator retains the quantum coherence, whereas the
damped subsystem of the BFT oscillator exhibits both quantum decoherence and
classical correlation. Furthermore the amplified subsystem of the BFT
oscillator shows the same degree of quantum decohernce and classical
correlation. | 0202089v1 |
2002-12-05 | Time correlated quantum amplitude damping channel | We analyze the problem of sending classical information through qubit
channels where successive uses of the channel are correlated. This work extends
the analysis of C. Macchiavello and G. M. Palma to the case of a non-Pauli
channel - the amplitude damping channel. Using the channel description outlined
in S. Daffer, et al, we derive the correlated amplitude damping channel. We
obtain a similar result to C. Macchiavello and G. M. Palma, that is, that under
certain conditions on the degree of channel memory, the use of entangled input
signals may enhance the information transmission compared to the use of product
input signals. | 0212032v1 |
2005-06-01 | Quantum damped oscillator I: dissipation and resonances | Quantization of a damped harmonic oscillator leads to so called Bateman's
dual system. The corresponding Bateman's Hamiltonian, being a self-adjoint
operator, displays the discrete family of complex eigenvalues. We show that
they correspond to the poles of energy eigenvectors and the corresponding
resolvent operator when continued to the complex energy plane. Therefore, the
corresponding generalized eigenvectors may be interpreted as resonant states
which are responsible for the irreversible quantum dynamics of a damped
harmonic oscillator. | 0506007v1 |
2005-10-19 | The damped harmonic oscillator in deformation quantization | We propose a new approach to the quantization of the damped harmonic
oscillator in the framework of deformation quantization. The quantization is
performed in the Schr\"{o}dinger picture by a star-product induced by a
modified "Poisson bracket". We determine the eigenstates in the damped regime
and compute the transition probability between states of the undamped harmonic
oscillator after the system was submitted to dissipation. | 0510150v1 |
2006-04-28 | The characteristic function of optical evolution | The master equation of quantum optical density operator is transformed to the
equation of characteristic function. The parametric amplification and amplitude
damping as well as the phase damping are considered. The solution for the most
general initial quantum state is obtained for parametric amplification and
amplitude damping. The purity of one mode Gaussian system and the entanglement
of two mode Gaussian system are studied. | 0604208v4 |
2007-01-13 | Wave-particle duality in the damped harmonic oscillator | Quantization of the damped harmonic oscillator is taken as leitmotiv to
gently introduce elements of quantum probability theory for physicists. To this
end, we take (graduate) students in physics as entry level and explain the
physical intuition and motivation behind the, sometimes overwhelming, math
machinery of quantum probability theory.
The main text starts with the quantization of the (undamped) harmonic
oscillator from the Heisenberg and Schroedinger point of view. We show how both
treatments are special instances of a quantum probabilistic quantization
procedure: the second quantization functor. We then apply the second
quantization functor to the damped harmonic oscillator and interpret the
quantum dynamics of the position and energy operator as stochastic processes. | 0701082v1 |
2007-04-11 | Time dependence of joint entropy of oscillating quantum systems | The time dependent entropy (or Leipnik's entropy) of harmonic and damped
harmonic oscillators is extensively investigated by using time dependent wave
function obtained by the Feynman path integral method. Our results for simple
harmonic oscillator are in agrement with the literature. However, the joint
entropy of damped harmonic oscillator shows remarkable discontinuity with time
for certain values of damping factor. According to the results, the envelop of
the joint entropy curve increases with time monotonically. This results is the
general properties of the envelop of the joint entropy curve for quantum
systems. | 0704.1370v3 |
2007-06-30 | The squeezed generalized amplitude damping channel | Squeezing of a thermal bath introduces new features absent in an open quantum
system interacting with an uncorrelated (zero squeezing) thermal bath. The
resulting dynamics, governed by a Lindblad-type evolution, extends the concept
of a generalized amplitude damping channel, which corresponds to a dissipative
interaction with a purely thermal bath. Here we present the Kraus
representation of this map, which we call the squeezed generalized amplitude
damping channel. As an application of this channel to quantum information, we
study the classical capacity of this channel. | 0707.0059v2 |
2007-07-09 | Memory in a nonlocally damped oscillator | We analyze the new equation of motion for the damped oscillator. It differs
from the standard one by a damping term which is nonlocal in time and hence it
gives rise to a system with memory. Both classical and quantum analysis is
performed. The characteristic feature of this nonlocal system is that it breaks
local composition low for the classical Hamiltonian dynamics and the
corresponding quantum propagator. | 0707.1199v2 |
2007-07-20 | Dynamics of Bloch Oscillations in Disordered Lattice Potentials | We present a detailed analysis of the dynamics of Bloch oscillations of
Bose-Einstein condensates in disordered lattice potentials. Due to the disorder
and the interparticle interactions these oscillations undergo a dephasing,
reflected in a damping of the center of mass oscillations, which should be
observable under realistic experimental conditions. The interplay between
interactions and disorder is far from trivial, ranging from an
interaction-enhanced damping due to modulational instability for strong
interactions, to an interaction-reduced damping due to a dynamical screening of
the disorder potential. | 0707.3131v1 |
2007-09-14 | Damping of field-induced chemical potential oscillations in ideal two-band compensated metals | The field and temperature dependence of the de Haas-van Alphen oscillations
spectrum is studied for an ideal two-dimensional compensated metal. It is shown
that the chemical potential oscillations, involved in the frequency
combinations observed in the case of uncompensated orbits, are strongly damped
and can even be suppressed when the effective masses of the electron- and
hole-type orbits are the same. When magnetic breakdown between bands occurs,
this damping is even more pronounced and the Lifshits-Kosevich formalism
accounts for the data in a wide field range. | 0709.2223v2 |
2007-09-14 | Update on Ion Studies | The effect of ions has received one of the highest priorities in R&D for the
damping rings of the International Linear Collider(ILC). It is detrimental to
the performance of the electron damping ring. In this note, an update
concerning the ion studies for the ILC damping ring is given. We investigate
the gap role and irregular fill pattern in the ring.The ion density reduction
in different fills is calculated analytically. Simulation results are also
presented. | 0709.2248v1 |
2007-10-03 | Stability of a Nonlinear Axially Moving String With the Kelvin-Voigt Damping | In this paper, a nonlinear axially moving string with the Kelvin-Voigt
damping is considered. It is proved that the string is stable, i.e., its
transversal displacement converges to zero when the axial speed of the string
is less than a certain critical value. The proof is established by showing that
a Lyapunov function corresponding to the string decays to zero exponentially.
It is also shown that the string displacement is bounded when a bounded
distributed force is applied to it transversally. Furthermore, a few open
problems regarding the stability and stabilization of strings with the
Kelvin-Voigt damping are stated. | 0710.0872v1 |
2007-10-15 | General Solution of the Quantum Damped Harmonic Oscillator | In this paper the general solution of the quantum damped harmonic oscillator
is given. | 0710.2724v4 |
2008-02-21 | Identification of Test Structures for Reduced Order Modeling of the Squeeze Film Damping in Mems | In this study the dynamic behaviour of perforated microplates oscillating
under the effect of squeeze film damping is analyzed. A numerical approach is
adopted to predict the effects of damping and stiffness transferred from the
surrounding ambient air to oscillating structures ; the effect of hole's cross
section and plate's extension is observed. Results obtained by F.E.M. models
are compared with experimental measurements performed by an optical
interferometric microscope. | 0802.3076v1 |
2008-03-14 | Current-induced noise and damping in non-uniform ferromagnets | In the presence of spatial variation of the magnetization direction, electric
current noise causes a fluctuating spin-transfer torque that increases the
fluctuations of the ferromagnetic order parameter. By the
fluctuation-dissipation theorem, the equilibrium fluctuations are related to
the magnetization damping, which in non-uniform ferromagnets acquires a
nonlocal tensor structure. In biased ferromagnets, shot noise can become the
dominant contribution to the magnetization noise at low temperatures.
Considering spin spirals as a simple example, we show that the current-induced
noise and damping is significant. | 0803.2175v1 |
2008-04-23 | Ion acoustic waves in the plasma with the power-law q-distribution in nonextensive statistics | We investigate the dispersion relation and Landau damping of ion acoustic
waves in the collisionless magnetic-field-free plasma if it is described by the
nonextensive q-distributions of Tsallis statistics. We show that the increased
numbers of superthermal particles and low velocity particles can explain the
strengthened and weakened modes of Landau damping, respectively, with the
q-distribution. When the ion temperature is equal to the electron temperature,
the weakly damped waves are found to be the distributions with small values of
q. | 0804.3732v1 |
2008-07-23 | Tunneling-induced damping of phase coherence revivals in deep optical lattices | We consider phase coherence collapse and revival in deep optical lattices,
and calculate within the Bose-Hubbard model the revival amplitude damping
incurred by a finite tunneling coupling of the lattice wells (after sweeping
from the superfluid to the Mott phase). Deriving scaling laws for the
corresponding decay of first-order coherence revival in terms of filling
factor, final lattice depth, and number of tunneling coupling partners, we
estimate whether revival-damping related to tunneling between sites can be or
even has already been observed in experiment. | 0807.3627v2 |
2008-07-31 | Generalized Theory of Landau Damping | Collisionless damping of electrical waves in plasma is investigated in the
frame of the classical formulation of the problem. The new principle of
regularization of the singular integral is used. The exact solution of the
corresponding dispersion equation is obtained. The results of calculations lead
to existence of discrete spectrum of frequencies and discrete spectrum of
dispersion curves. Analytical results are in good coincidence with results of
direct mathematical experiments. Key words: Foundations of the theory of
transport processes and statistical physics; Boltzmann physical kinetics;
damping of plasma waves, linear theory of wave`s propagation PACS: 67.55.Fa,
67.55.Hc | 0807.5007v1 |
2008-08-05 | Radiation damping, noncommutativity and duality | In this work, our main objective is to construct a N=2 supersymmetric
extension of the nonrelativistic $(2+1)$-dimensional model describing the
radiation damping on the noncommutative plane with scalar (electric) and vector
(magnetic) interactions by the N=2 superfield technique. We also introduce a
dual equivalent action to the radiation damping one using the Noether
procedure. | 0808.0694v2 |
2008-10-06 | Local existence and exponential growth for a semilinear damped wave equation with dynamic boundary conditions | In this paper we consider a multi-dimensional damped semiliear wave equation
with dynamic boundary conditions, related to the Kelvin-Voigt damping. We
firstly prove the local existence by using the Faedo-Galerkin approximations
combined with a contraction mapping theorem. Secondly, the exponential growth
of the energy and the $L^p$ norm of the solution is presented. | 0810.1013v1 |
2008-11-20 | An explanation for the pseudogap of high-temperature superconductors based on quantum optics | We first explain the pseudogap of high-temperature superconductivity based on
an approach of quantum optics. After introducing a damping factor for the
lifetime $\tau$ of quasiparticles, the superconducting dome is naturally
produced, and the pseudogap is the consequence of pairing with damped
coherence. We derive a new expression of Ginzburg-Landau free energy density,
in which a six-order term due to decoherence damping effect is included.
Without invoking any microscopic pairing mechanism, this approach provides a
simple universal equation of second-order phase transition, which can be
reduced to two well-known empirical scaling equations: the superconducting dome
Presland-Tallon equation, and the normal-state pseudogap crossover temperature
$T^{*}$ line. | 0811.3262v1 |
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