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2007-12-19
Cosmic String Dynamics and Evolution in Warped Spacetime
We study the dynamics and evolution of Nambu-Goto strings in a warped spacetime, where the warp factor is a function of the internal coordinates giving rise to a `throat' region. The microscopic equations of motion for strings in this background include potential and friction terms, which attract the strings towards th...
0712.3224v2
2007-12-20
The Critical Exponent of the Fractional Langevin Equation is $α_c\approx 0.402$
We investigate the dynamical phase diagram of the fractional Langevin equation and show that critical exponents mark dynamical transitions in the behavior of the system. For a free and harmonically bound particle the critical exponent $\alpha_c= 0.402\pm 0.002$ marks a transition to a non-monotonic under-damped phase. ...
0712.3407v1
2008-01-24
Particle Acceleration by Fast Modes in Solar Flares
We address the problem of particle acceleration in solar flares by fast modes which may be excited during the reconnection and undergo cascade and are subjected to damping. We extend the calculations beyond quasilinear approximation and compare the acceleration and scattering by transit time damping and gyroresonance i...
0801.3786v2
2008-02-07
Analysis of squeal noise and mode coupling instabilities including damping and gyroscopic effects
This paper deals with an audible disturbance known as automotive clutch squeal noise from the viewpoint of friction-induced mode coupling instability. Firstly, an auto-coupling model is presented showing a non-conservative circulatory effect originating from friction forces. Secondly, the stability of an equilibrium is...
0802.0923v1
2008-02-12
Nonlinear Saturation of g-modes in Proto-Neutron Stars: Quieting the Acoustic Engine
According to Burrows et al.'s acoustic mechanism for core-collapse supernova explosions, the primary, l=1, g-mode in the core of the proto-neutron star is excited to an energy of ~ 10^{50} ergs and damps by the emission of sound waves. Here we calculate the damping of the primary mode by the parametric instability, i.e...
0802.1522v3
2008-02-21
Gas Damping Coefficient Research for MEMS Comb Linear Vibration Gyroscope
Silicon-MEMS gyroscope is an important part of MEMS (Micro Electrical Mechanical System). There are some disturb ignored in traditional gyroscope that must be evaluated newly because of its smaller size (reach the level of micron). In these disturb, the air pressure largely influences the performance of MEMS gyroscope....
0802.3048v1
2008-03-03
Damped harmonic oscillator interpretation of the soft-state power spectra of Cyg X-1
We develop a model of an accretion disc in which the variability induced at a given radius is governed by a damped harmonic oscillator at the corresponding epicyclic frequency. That variability induces both linear and non-linear responses in the locally emitted radiation. The total observed variability of a source is t...
0803.0238v2
2008-03-05
The Secular Evolution of a Close Ring-Satellite System: The Excitation of Spiral Density Waves at a Nearby Gap Edge
The Lagrange planetary equations are used to study to secular evolution of a small, eccentric satellite that orbits within a narrow gap in a broad, self-gravitating planetary ring. These equations show that the satellite's secular perturbations of the ring will excite a very long-wavelength spiral density wave that pro...
0803.0576v1
2008-03-06
Hypersound damping in vitreous silica measured by picosecond acoustics
The attenuation of longitudinal acoustic phonons up to frequencies nearing 250 GHz is measured in vitreous silica with a picosecond optical technique. Taking advantage of interferences on the probe beam, difficulties encountered in early pioneering experiments are alleviated. Sound damping at 250 GHz and room temperatu...
0803.0832v1
2008-03-07
Resonance distribution in open quantum chaotic systems
In order to study the resonance spectra of chaotic cavities subject to some damping (which can be due to absorption or partial reflection at the boundaries), we use a model of damped quantum maps. In the high-frequency limit, the distribution of (quantum) decay rates is shown to cluster near a ``typical'' value, which ...
0803.1075v4
2008-04-03
Single flux quantum circuits with damping based on dissipative transmission lines
We propose and demonstrate the functioning of a special Rapid Single Flux Quantum (RSFQ) circuit with frequency-dependent damping. This damping is achieved by shunting individual Josephson junctions by pieces of open-ended RC transmission lines. Our circuit includes a toggle flip-flop cell, Josephson transmission lines...
0804.0442v1
2008-05-14
Reconciling results of LSND, MiniBooNE and other experiments with soft decoherence
We propose an explanation of the LSND signal via quantum-decoherence of the mass states, which leads to damping of the interference terms in the oscillation probabilities. The decoherence parameters as well as their energy dependence are chosen in such a way that the damping affects only oscillations with the large (at...
0805.2098v1
2008-06-02
Observations of Solar Doppler Shift Oscillations with the EUV Imaging Spectrometer on Hinode
Damped Doppler shift oscillations have been observed in emission lines from ions formed at flare temperatures with the Solar Ultraviolet Measurements of Emitted Radiation spectrometer on the Solar and Heliospheric Observatory and with the Bragg Crystal Spectrometer on Yohkoh. This Letter reports the detection of low-am...
0806.0265v1
2008-07-07
Using squeezed field to preserve two-atom entanglement against spontaneous emissions
Tunable interaction between two atoms in a cavity is realized by interacting the two atoms with an extra controllable single-mode squeezed field. Such a controllable interaction can be further used to control entanglement between the two atoms against amplitude damping decoherence caused by spontaneous emissions. For t...
0807.0965v2
2008-07-17
Connecting high-redshift galaxy populations through observations of local Damped Lyman Alpha dwarf galaxies
I report on observations of the z=0.01 dwarf galaxy SBS1543+593 which is projected onto the background QSO HS1543+5921. As a star-forming galaxy first noted in emission, this dwarf is playing a pivotal role in our understanding of high-redshift galaxy populations, because it also gives rise to a Damped Lyman Alpha syst...
0807.2853v1
2008-07-26
A Monte Carlo Method for Modeling Thermal Damping: Beyond the Brownian-Motion Master Equation
The "standard" Brownian motion master equation, used to describe thermal damping, is not completely positive, and does not admit a Monte Carlo method, important in numerical simulations. To eliminate both these problems one must add a term that generates additional position diffusion. He we show that one can obtain a c...
0807.4211v3
2008-07-31
Finite-dimensional attractors for the quasi-linear strongly-damped wave equation
We present a new method of investigating the so-called quasi-linear strongly damped wave equations $$ \partial_t^2u-\gamma\partial_t\Delta_x u-\Delta_x u+f(u)= \nabla_x\cdot \phi'(\nabla_x u)+g $$ in bounded 3D domains. This method allows us to establish the existence and uniqueness of energy solutions in the case wher...
0807.5078v1
2008-08-01
Field-Driven Domain-Wall Dynamics in GaMnAs Films with Perpendicular Anisotropy
We combine magneto-optical imaging and a magnetic field pulse technique to study domain wall dynamics in a ferromagnetic (Ga,Mn)As layer with perpendicular easy axis. Contrary to ultrathin metallic layers, the depinning field is found to be smaller than the Walker field, thereby allowing for the observation of the stea...
0808.0119v1
2008-08-11
Effect of frequency and temperature on microwave-induced magnetoresistance oscillations in two-dimensional electron systems
Experimental results on microwave-induced magnetoresistance oscillation in two-dimensional electron systems show a similar behavior of these systems regarding temperature and microwave frequency. It is found that these oscillations tend to quench when frequency or temperature increase, approaching magnetoresistance to ...
0808.1489v1
2008-09-26
Damping and magnetic anisotropy of ferromagnetic GaMnAs thin films
The magnetic properties of annealed, epitaxial Ga0.93Mn0.07As layers under tensile and compressive stress have been investigated by X-band (9GHz) and Q-band (35GHz) ferromagnetic resonance (FMR) spectroscopy. From the analysis of the linewidths of the uniform mode spectra the FMR Gilbert damping factor "alpha" has been...
0809.4644v2
2008-11-13
Higher order energy decay rates for damped wave equations with variable coefficients
Under appropriate assumptions the energy of wave equations with damping and variable coefficients $c(x)u_{tt}-\hbox{div}(b(x)\nabla u)+a(x)u_t =h(x)$ has been shown to decay. Determining the rate of decay for the higher order energies involving the $k$th order spatial and time derivatives has been an open problem with ...
0811.2159v1
2009-01-12
Nonlinear Wigner solid transport over superfluid helium under AC conditions
Nonlinear transport properties of the two-dimensional Wigner solid of surface electrons on superfluid helium are studied for alternating current conditions. For time-averaged quantities like Fourier coefficients, the field-velocity characteristics are shown to be qualitatively different as compared to that found in the...
0901.1508v1
2009-01-14
Brownian motion with respect to time-changing Riemannian metrics, applications to Ricci flow
We generalize Brownian motion on a Riemannian manifold to the case of a family of metrics which depends on time. Such questions are natural for equations like the heat equation with respect to time dependent Laplacians (inhomogeneous diffusions). In this paper we are in particular interested in the Ricci flow which pro...
0901.1999v2
2009-01-26
Damping of sound waves in superfluid nucleon-hyperon matter of neutron stars
We consider sound waves in superfluid nucleon-hyperon matter of massive neutron-star cores. We calculate and analyze the speeds of sound modes and their damping times due to the shear viscosity and non-equilibrium weak processes of particle transformations. For that, we employ the dissipative relativistic hydrodynamics...
0901.4108v1
2009-03-02
Attenuation and damping of electromagnetic fields: Influence of inertia and displacement current
New results for attenuation and damping of electromagnetic fields in rigid conducting media are derived under the conjugate influence of inertia due to charge carriers and displacement current. Inertial effects are described by a relaxation time for the current density in the realm of an extended Ohm's law. The classic...
0903.0210v1
2009-04-06
Scrutinizing single-qubit quantum channels: Theory and experiment with trapped ions
We report experimental implementation of various types of qubit channels using an individual trapped ion. We analyzed experimental data and we performed tomographic reconstruction of quantum channels based on these data. Specifically, we studied phase damping channels, where the damping acts either in the xy-plane of t...
0904.0923v1
2009-05-13
Time-dependent barrier passage of Two-dimensional non-Ohmic damping system
The time-dependent barrier passage of an anomalous damping system is studied via the generalized Langevin equation (GLE) with non-Ohmic memory damping friction tensor and corresponding thermal colored noise tensor describing a particle passing over the saddle point of a two-dimensional quadratic potential energy surfac...
0905.2074v1
2009-06-04
Viscous cavity damping of a microlever in a simple fluid
We consider the problem of oscillation damping in air of a thermally actuated microlever as it is gradually approached towards an infinite wall in parallel geometry. As the gap is decreased from 20 nm down to 400 nm, we observe the increasing damping of the lever Brownian motion in the fluid laminar regime. This manife...
0906.0782v1
2009-06-19
Wakefield damping for the CLIC crab cavity
A crab cavity is required in the CLIC to allow effective head-on collision of bunches at the IP. A high operating frequency is preferred as the deflection voltage required for a given rotation angle and the RF phase tolerance for a crab cavity are inversely proportional to the operating frequency. The short bunch spaci...
0906.3593v1
2009-07-06
Non-Fermi liquid behavior due to U(1) gauge field in two dimensions
We study the damping rate of massless Dirac fermions due to the U(1) gauge field in (2+1)-dimensional quantum electrodynamics. In the absence of a Maxwell term for the gauge field, the fermion damping rate $\mathrm{Im}\Sigma(\omega,T)$ is found to diverge in both perturbative and self-consistent results. In the presenc...
0907.1022v3
2009-07-30
Gas damping force noise on a macroscopic test body in an infinite gas reservoir
We present a simple analysis of the force noise associated with the mechanical damping of the motion of a test body surrounded by a large volume of rarefied gas. The calculation is performed considering the momentum imparted by inelastic collisions against the sides of a cubic test mass, and for other geometries for wh...
0907.5375v2
2009-08-26
Influence of an external magnetic field on forced turbulence in a swirling flow of liquid metal
We report an experimental investigation on the influence of an external magnetic field on forced 3D turbulence of liquid gallium in a closed vessel. We observe an exponential damping of the turbulent velocity fluctuations as a function of the interaction parameter N (ratio of Lorentz force over inertial terms of the Na...
0908.3821v1
2009-09-30
Electronic damping of molecular motion at metal surfaces
A method for the calculation of the damping rate due to electron-hole pair excitation for atomic and molecular motion at metal surfaces is presented. The theoretical basis is provided by Time Dependent Density Functional Theory (TDDFT) in the quasi-static limit and calculations are performed within a standard plane-wav...
0909.5495v1
2009-10-27
On the Interpretation of Magnetic Helicity Signatures in the Dissipation Range of Solar Wind Turbulence
Measurements of small-scale turbulent fluctuations in the solar wind find a non-zero right-handed magnetic helicity. This has been interpreted as evidence for ion cyclotron damping. However, theoretical and empirical evidence suggests that the majority of the energy in solar wind turbulence resides in low frequency ani...
0910.5023v1
2009-12-08
Coupling Photosphere and Corona: Linear and Turbulent Regimes
In a recent work Grappin et al. [1] have shown that low- frequency movements can be transmitted from one footpoint to the other along a magnetic loop, thus mimicking a friction effect of the corona on the photosphere, and invalidating the line-tying approximation. We consider here successively the effect of high freque...
0912.1497v1
2009-12-16
The role of $r$-mode damping in the thermal evolution of neutron stars
The thermal evolution of neutron stars (NSs) is investigated by coupling with the evolution of $\textit{r}$-mode instability that is described by a second order model.The heating effect due to shear viscous damping of the $\textit{r}$-modes enables us to understand the high temperature of two young pulsars (i.e., PSR B...
0912.3052v1
2009-12-25
Noisy non-transitive quantum games
We study the effect of quantum noise in 3 by 3 entangled quantum games. By considering different noisy quantum channels we analyze that how a two-player, three-strategy Rock-Scissor-Paper game is influenced by the quantum noise. We consider the winning non-transitive strategies R, S and P such as R beats S, S beats P, ...
0912.4961v1
2010-01-26
Damping in high-frequency metallic nanomechanical resonators
We have studied damping in polycrystalline Al nanomechanical resonators by measuring the temperature dependence of their resonance frequency and quality factor over a temperature range of 0.1 - 4 K. Two regimes are clearly distinguished with a crossover temperature of 1 K. Below 1 K we observe a logarithmic temperature...
1001.4612v1
2010-04-28
Inviscid dynamical structures near Couette flow
Consider inviscid fluids in a channel {-1<y<1}. For the Couette flow v_0=(y,0), the vertical velocity of solutions to the linearized Euler equation at v_0 decays in time. At the nonlinear level, such inviscid damping has not been proved. First, we show that in any (vorticity) H^{s}(s<(3/2)) neighborhood of Couette flow...
1004.5149v1
2010-06-14
Parallel electric field amplification by phase-mixing of Alfven waves
Previous numerical studies have identified "phase mixing" of low-frequency Alfven waves as a mean of parallel electric field amplification and acceleration of electrons in a collisionless plasma. Theoretical explanations are given of how this produces an amplification of the parallel electric field, and as a consequenc...
1006.2729v1
2010-07-19
Anomalously large damping of long-wavelength quasiparticles caused by long-range interaction
We demonstrate that long-range interaction in a system can lead to a very strong interaction between long-wavelength quasiparticles and make them heavily damped. In particular, we discuss magnon spectrum using 1/S expansion in 3D Heisenberg ferromagnet (FM) with arbitrary small dipolar forces at T<<T_C. We obtain that ...
1007.3081v2
2010-07-29
The Quasinormal Mode Spectrum of a Kerr Black Hole in the Eikonal Limit
It is well established that the response of a black hole to a generic perturbation is characterized by a spectrum of damped resonances, called quasinormal modes; and that, in the limit of large angular momentum ($l \gg 1$), the quasinormal mode frequency spectrum is related to the properties of unstable null orbits. In...
1007.5097v1
2010-08-30
Caldeira-Leggett Model, Landau Damping, and the Vlasov-Poisson System
The Caldeira-Leggett Hamiltonian (Eq. (1) below) describes the interaction of a discrete harmonic oscillator with a continuous bath of harmonic oscillators. This system is a standard model of dissipation in macroscopic low temperature physics, and has applications to superconductors, quantum computing, and macroscopic ...
1008.5190v1
2010-09-09
A number-conserving linear response study of low-velocity ion stopping in a collisional magnetized classical plasma
The results of a theoretical investigation on the low-velocity stopping power of the ions moving in a magnetized collisional plasma are presented. The stopping power for an ion is calculated employing linear response theory using the dielectric function approach. The collisions, which leads to a damping of the excitati...
1009.1700v1
2010-10-03
A High Phase Advance Damped and Detuned Structure for the Main Linacs of Clic
The main accelerating structures for the CLIC are designed to operate at an average accelerating gradient of 100 MV/m. The accelerating frequency has been optimised to 11.994 GHz with a phase advance of 2{\pi}/3 of the main accelerating mode. The moderately damped and detuned structure (DDS) design is being studied as ...
1010.0438v1
2010-10-23
Environmental influences on Quantum Monty Hall problem
We reformulate the quantum Monty Hall problem in the presence of decoherence. The decoherence destroys the fairness of the game. A new Nash equilibrium for a particular strategy profile in the presence of decoherence emerges. It is shown that in the presence of decoherence under the action of amplitude damping channel,...
1010.4875v2
2010-12-14
Controlling transfer of quantum correlations among bi-partitions of a composite quantum system by combining noisy environments
The correlation dynamics is investigated for various bi-partitions of a composite system consisting of two qubits, and two independent and non-identical noisy environments. The two qubits have no direct interaction with each other and locally interact with their environments. Classical and quantum correlations includin...
1012.3033v1
2010-12-22
Viscous damping of r-modes: Small amplitude instability
We study the viscous damping of r-modes of compact stars and analyze in detail the regions where small amplitude modes are unstable to the emission of gravitational radiation. We present general expressions for the viscous damping times for arbitrary forms of interacting dense matter and derive general semi-analytic re...
1012.4883v2
2010-12-25
Screw-pitch effect and velocity oscillation of domain-wall in ferromagnetic nanowire driven by spin-polarized current
We investigate the dynamics of domain wall in ferromagnetic nanowire with spin-transfer torque. The critical current condition is obtained analytically. Below the critical current, we get the static domain wall solution which shows that the spin-polarized current can't drive domain wall moving continuously. In this cas...
1012.5473v1
2010-12-27
Phenomenology of Current-Induced Dynamics in Antiferromagnets
We derive a phenomenological theory of current-induced staggered magnetization dynamics in antiferromagnets. The theory captures the reactive and dissipative current-induced torques and the conventional effects of magnetic fields and damping. A Walker ansatz describes the dc current-induced domain-wall motion when ther...
1012.5655v2
2011-02-02
Harmonic Oscillator in Heat Bath: Exact simulation of time-lapse-recorded data, exact analytical benchmark statistics
The stochastic dynamics of the damped harmonic oscillator in a heat bath is simulated with an algorithm that is exact for time steps of arbitrary size. Exact analytical results are given for correlation functions and power spectra in the form they acquire when computed from experimental time-lapse recordings. Three app...
1102.0524v1
2011-03-03
Determination of the pairing state in iron-based superconductors through neutron scattering
We calculate the spin susceptibility in the s_{+-} and s_{++} superconducting states of the iron pnictides using the effective five orbital model and considering the quasiparticle damping. For the experimentally evaluated magnitude of the quasiparticle damping and the superconducting gap, the results at the wave vector...
1103.0586v2
2011-03-03
Transmission of classical and quantum information through a quantum memory channel with damping
We consider the transfer of classical and quantum information through a memory amplitude damping channel. Such a quantum channel is modeled as a damped harmonic oscillator, the interaction between the information carriers - a train of qubits - and the oscillator being of the Jaynes-Cummings kind. We prove that this mem...
1103.0747v2
2011-03-18
Time-periodic solitons in a damped-driven nonlinear Schrödinger equation
Time-periodic solitons of the parametrically driven damped nonlinear Schr\"odinger equation are obtained as solutions of the boundary-value problem on a two-dimensional spatiotemporal domain. We follow the transformation of the periodic solitons as the strength of the driver is varied. The resulting bifurcation diagram...
1103.3604v1
2011-03-28
Motion of position-dependent mass as a damping-antidamping process: Application to the Fermi gas and to the Morse potential
The object of this paper is to investigate, classically and quantum mechanically, the relation existing between the position-dependent effective mass and damping-antidamping dynamics. The quantization of the equations of motion is carried out using the geometric interpretation of the motion, and we compare it with the ...
1103.5440v3
2011-04-08
Magnetization Dissipation in Ferromagnets from Scattering Theory
The magnetization dynamics of ferromagnets are often formulated in terms of the Landau-Lifshitz-Gilbert (LLG) equation. The reactive part of this equation describes the response of the magnetization in terms of effective fields, whereas the dissipative part is parameterized by the Gilbert damping tensor. We formulate a...
1104.1625v1
2011-04-30
Resonantly Damped Propagating Kink Waves in Longitudinally Stratified Solar Waveguides
It has been shown that resonant absorption is a robust physical mechanism to explain the observed damping of magnetohydrodynamic (MHD) kink waves in the solar atmosphere due to naturally occurring plasma inhomogeneity in the direction transverse to the direction of the magnetic field. Theoretical studies of this dampin...
1105.0067v1
2011-05-05
The effect of twisted magnetic field on the resonant absorption of MHD waves in coronal loops
The standing quasi modes in a cylindrical incompressible flux tube with magnetic twist that undergoes a radial density structuring is considered in ideal magnetohydrodynamics (MHD). The radial structuring is assumed to be a linearly varying density profile. Using the relevant connection formulae, the dispersion relatio...
1105.1120v1
2011-05-05
Interpreting Graph Cuts as a Max-Product Algorithm
The maximum a posteriori (MAP) configuration of binary variable models with submodular graph-structured energy functions can be found efficiently and exactly by graph cuts. Max-product belief propagation (MP) has been shown to be suboptimal on this class of energy functions by a canonical counterexample where MP conver...
1105.1178v1
2011-05-14
Crossovers in the non-Markovian dynamics of two-qubit entanglements
We study the entanglement dynamics of two non-interacting, spatially separated qubits subject to local environment noises. Based on exactly solvable models for non-Markovian amplitude damping and phase damping noises, we are able to analyze the entanglement dynamics of the two qubits for different coupling bandwidths a...
1105.2859v2
2011-06-22
Tunable Magnonic Frequency and Damping in [Co/Pd]8 Multilayers with Variable Co Layer Thickness
We report the experimental observation of collective picosecond magnetization dynamics in [Co/Pd]8 multilayers with perpendicular magnetic anisotropy. The precession frequency shows large and systematic variation from about 5 GHz to about 90 GHz with the decrease in the Co layer thickness from 1.0 nm to 0.22 nm due to ...
1106.4491v1
2011-07-04
An HI column density threshold for cold gas formation in the Galaxy
We report the discovery of a threshold in the HI column density of Galactic gas clouds below which the formation of the cold phase of HI is inhibited. This threshold is at $N_{HI} = 2 \times 10^{20}$ per cm$^{2}$; sightlines with lower HI column densities have high spin temperatures (median $T_s \sim 1800$ K), indicati...
1107.0744v2
2011-07-11
One-dimensional vertical dust strings in a glass box
The oscillation spectrum of a one-dimensional vertical dust string formed inside a glass box on top of the lower electrode in a GEC reference cell was studied. A mechanism for creating a single vertical dust string is described. It is shown that the oscillation amplitudes, resonance frequencies, damping coefficients, a...
1107.2074v1
2011-08-22
On conditions for asymptotic stability of dissipative infinite-dimensional systems with intermittent damping
We study the asymptotic stability of a dissipative evolution in a Hilbert space subject to intermittent damping. We observe that, even if the intermittence satisfies a persistent excitation condition, if the Hilbert space is infinite-dimensional then the system needs not being asymptotically stable (not even in the wea...
1108.4327v2
2011-08-26
Aligned Major Axes in a Planetary System without Tidal Evolution: The 61 Virginis example
Tidal damping of one of the orbits in a planetary system can lead to aligned major-axes (the so-called "fixed-point" condition), but currently aligned major axes do not necessarily imply such a history. An example is the nominal orbital solution for the 61 Virginis system where two orbits librate about alignment, but e...
1108.5369v1
2011-09-09
Optimal linear optical implementation of a single-qubit damping channel
We experimentally demonstrate a single-qubit decohering quantum channel using linear optics. We implement the channel, whose special cases include both the amplitude-damping channel and the bit-flip channel, using a single, static optical setup. Following a recent theoretical result [M. Piani et al., Phys. Rev. A, 84, ...
1109.2070v1
2011-11-20
Detection of picosecond magnetization dynamics of 50 nm magnetic dots down to the single dot regime
We report an all-optical time-domain detection of picosecond magnetization dynamics of arrays of 50 nm Ni80Fe20 (permalloy) dots down to the single nanodot regime. In the single nanodot regime the dynamics reveals one dominant resonant mode corresponding to the edge mode of the 50 nm dot with slightly higher damping th...
1111.4625v1
2012-01-09
Universal response of optimal granular damping devices
Granular damping devices constitute an emerging technology for the attenuation of vibrations based on the dissipative nature of particle collisions. We show that the performance of such devices is independent of the material properties of the particles for working conditions where damping is optimal. Even the suppressi...
1201.1866v2
2012-01-09
Radiative energy loss reduction in an absorptive plasma
The influence of the damping of radiation on the radiative energy loss spectrum of a relativistic charge in an infinite, absorptive plasma is studied. We find increasing reduction of the spectrum with increasing damping. Our studies, which represent an Abelian approximation for the colour charge dynamics in the quark-g...
1201.1890v1
2012-01-10
Nonequilibrium Damping of Collective Motion of Homogeneous Cold Fermi Condensates with Feshbach Resonances
Collisionless damping of a condensate of cold Fermi atoms, whose scattering is controlled by a Feshbach resonance, is explored throughout the BCS and BEC regimes when small perturbations on its phase and amplitude modes are turned on to drive the system slightly out of equilibrium. Using a one-loop effective action, we...
1201.2019v1
2012-01-30
Modeling electricity spot prices using mean-reverting multifractal processes
We discuss stochastic modeling of volatility persistence and anti-correlations in electricity spot prices, and for this purpose we present two mean-reverting versions of the multifractal random walk (MRW). In the first model the anti-correlations are modeled in the same way as in an Ornstein-Uhlenbeck process, i.e. via...
1201.6137v1
2012-05-14
Critical viscoelastic response in jammed solids
We determine the linear viscoelastic response of jammed packings of athermal repulsive viscous spheres, a model for emulsions, wet foams, and soft colloidal suspensions. We numerically measure the complex shear modulus, a fundamental characterization of the response, and demonstrate that low frequency response displays...
1205.2960v1
2012-06-11
Testing the 130 GeV gamma-ray line with high energy resolution detectors
Recently some hints of the existence of $\gamma$-ray line around 130 GeV are reported according to the analysis of Fermi-LAT data. If confirmed it would be the first direct evidence to show the existence of new physics beyond the standard model. Here we suggest that using the forthcoming high energy resolution $\gamma$...
1206.2241v2
2012-06-14
Finite-temperature dynamics of matter-wave dark solitons in linear and periodic potentials: an example of an anti-damped Josephson junction
We study matter-wave dark solitons in atomic Bose-Einstein condensates at finite temperatures, under the effect of linear and periodic potentials. Our model, namely a dissipative Gross-Pitaevskii equation, is treated analytically by means of dark soliton perturbation theory, which results in a Newtonian equation of mot...
1206.2993v1
2012-06-15
Damping of giant dipole resonance in hot rotating nuclei
The phonon damping model (PDM) is extended to include the effect of angular momentum at finite temperature. The model is applied to the study of damping of giant dipole resonance (GDR) in hot and noncollectively rotating spherical nuclei. The numerical results obtained for Mo88 and Sn106 show that the GDR width increas...
1206.3361v1
2012-06-18
Sampled-data design for robust control of a single qubit
This paper presents a sampled-data approach for the robust control of a single qubit (quantum bit). The required robustness is defined using a sliding mode domain and the control law is designed offline and then utilized online with a single qubit having bounded uncertainties. Two classes of uncertainties are considere...
1206.3897v2
2012-06-25
Trap anharmonicity and sloshing mode of a Fermi gas
For a gas trapped in a harmonic potential, the sloshing (or Kohn) mode is undamped and its frequency coincides with the trap frequency, independently of the statistics, interaction and temperature of the gas. However, experimental trap potentials have usually Gaussian shape and anharmonicity effects appear as the tempe...
1206.5688v2
2012-09-06
Radiative energy loss in the absorptive QGP: taming the long formation lengths in coherent emission
In an absorptive plasma, damping of radiation mechanisms can influence the bremsstrahlung formation in case of large radiation formation lengths. We study qualitatively the influence of this effect on the gluon bremsstrahlung spectrum off heavy quarks in the quark-gluon plasma. Independent of the heavy-quark mass, the ...
1209.1149v1
2012-09-17
Power spectra in the eikonal approximation with adiabatic and non-adiabatic modes
We use the so-called eikonal approximation, recently introduced in the context of cosmological perturbation theory, to compute power spectra for multi-component fluids. We demonstrate that, at any given order in standard perturbation theory, multipoint power spectra do not depend on the large-scale adiabatic modes. Mor...
1209.3662v2
2012-09-26
Linear response theory for hydrodynamic and kinetic equations with long-range interactions
We apply the linear response theory to systems with long-range interactions described by hydrodynamic equations such as the Euler, Smoluchowski, and damped Euler equations. We analytically determine the response of the system submitted to a pulse and to a step function. We compare these results with those obtained for ...
1209.5987v1
2012-09-15
Phase mixing of propagating Alfven waves in a stratified atmosphere: Solar spicules
Alfvenic waves are thought to play an important role in coronal heating and solar wind acceleration. Recent observations by Hinode/SOT showed that the spicules mostly exhibit upward propagating high frequency waves. Here we investigate the dissipation of such waves due to phase mixing in stratified environment of solar...
1210.0485v1
2012-10-03
Effect of temperature and velocity on superlubricity
We study the effects of temperature and sliding velocity on superlubricity in numerical simulations of the Frenkel-Kontorova model. We show that resonant excitations of the phonons in an incommensurate sliding body lead to an effective friction and to thermal equilibrium with energy distributed over the internal degree...
1210.1124v1
2012-10-04
Basic microscopic plasma physics unified and simplified by N-body classical mechanics
Debye shielding, collisional transport, Landau damping of Langmuir waves, and spontaneous emission of these waves are introduced, in typical plasma physics textbooks, in different chapters. This paper provides a compact unified introduction to these phenomena without appealing to fluid or kinetic models, but by using N...
1210.1546v2
2012-10-11
Measurement of the damping of nuclear shell effect in the doubly magic $^{208}$Pb region
The damping of the nuclear shell effect with excitation energy has been measured through an analysis of the neutron spectra following the triton transfer in the $^7$Li induced reaction on $^{205}$Tl. The measured neutron spectra demonstrate the expected large shell correction energy for the nuclei in the vicinity of do...
1210.3213v2
2012-10-16
Optimal control of laser plasma instabilities using Spike Trains of Uneven Duration and Delay (STUD pulses) for ICF and IFE
An adaptive method of controlling parametric instabilities in laser produced plasmas is proposed. It involves fast temporal modulation of a laser pulse on the fastest instability's amplification time scale, adapting to changing and unknown plasma conditions. These pulses are comprised of on and off sequences having at ...
1210.4462v1
2012-10-28
Mass Dependence of Instabilities of an Oscillator with Multiplicative and Additive Noise
We study the instabilities of a harmonic oscillator subject to additive and dichotomous multiplicative noise, focussing on the dependance of the instability threshold on the mass. For multiplicative noise in the damping, the instability threshold is crossed as the mass is decreased, as long as the smaller damping is in...
1210.7433v1
2012-10-30
Extending the Concept of Analog Butterworth Filter for Fractional Order Systems
This paper proposes the design of Fractional Order (FO) Butterworth filter in complex w-plane (w=sq; q being any real number) considering the presence of under-damped, hyper-damped, ultra-damped poles. This is the first attempt to design such fractional Butterworth filters in complex w-plane instead of complex s-plane,...
1210.8194v3
2012-11-15
Spin transport and tunable Gilbert damping in a single-molecule magnet junction
We study time-dependent electronic and spin transport through an electronic level connected to two leads and coupled with a single-molecule magnet via exchange interaction. The molecular spin is treated as a classical variable and precesses around an external magnetic field. We derive expressions for charge and spin cu...
1211.3611v2
2012-11-24
Effects of Quantum Error Correction on Entanglement Sudden Death
We investigate the effects of error correction on non-local quantum coherence as a function of time, extending the study by Sainz and Bj\"ork. We consider error correction of amplitude damping, pure phase damping and combinations of amplitude and phase damping as they affect both fidelity and quantum entanglement. Init...
1211.5654v2
2012-12-04
Polarization dependence of phonon influences in exciton-biexciton quantum dot systems
We report on a strong dependence of the phonon-induced damping of Rabi dynamics in an optically driven exciton-biexciton quantum dot system on the polarization of the exciting pulse. While for a fixed pulse intensity the damping is maximal for linearly polarized excitation, it decreases with increasing ellipticity of t...
1212.0642v1
2012-12-10
Heat-induced damping modification in YIG/Pt hetero-structures
We experimentally demonstrate the manipulation of magnetization relaxation utilizing a temperature difference across the thickness of an yttrium iron garnet/platinum (YIG/Pt) hetero-structure: the damping is either increased or decreased depending on the sign of the temperature gradient. This effect might be explained ...
1212.2073v1
2012-12-13
Surface plasmon polaritons in a semi-bounded degenerate plasma: role of spatial dispersion and collisions
Surface plasmon polaritons (SPPs) in a semi-bounded degenerate plasma (e.g., a metal) are studied using the quasiclassical mean-field kinetic model, taking into account the spatial dispersion of the plasma (due to quantum degeneracy of electrons) and electron-ion (electron-lattice, for metals) collisions. SPP dispersio...
1212.3040v1
2012-12-13
Branching of quasinormal modes for nearly extremal Kerr black holes
We show that nearly extremal Kerr black holes have two distinct sets of quasinormal modes, which we call zero-damping modes (ZDMs) and damped modes (DMs). The ZDMs exist for all harmonic indices $l$ and $m \ge 0$, and their frequencies cluster onto the real axis in the extremal limit. The DMs have nonzero damping for a...
1212.3271v1
2012-12-31
Effects of lateral device size and material properties on the ferromagnetic resonance response of spinwave eigen-modes in magnetic devices
We analyze the effects of lateral device size and magnetic material parameters on the ferromagnetic resonance (FMR) response. Results presented are directly relevant to widely used FMR experimental techniques for extracting magnetic parameters from thin films, the results of which are often assumed to carry over to cor...
1212.6835v1
2013-01-16
Gain-tunable optomechanical cooling in a laser cavity
We study the optical cooling of the resonator mirror in a cavity-optomechanical system that contains an optical gain medium. We find that the optical damping rate is vanishingly small for an incoherently pumped laser above threshold. In the presence of an external coherent drive however, the optical damping rate can be...
1301.3762v2
2013-01-18
Adiabatic stability under semi-strong interactions: The weakly damped regime
We rigorously derive multi-pulse interaction laws for the semi-strong interactions in a family of singularly-perturbed and weakly-damped reaction-diffusion systems in one space dimension. Most significantly, we show the existence of a manifold of quasi-steady N-pulse solutions and identify a "normal-hyperbolicity" cond...
1301.4466v1
2013-01-24
Spin transport parameters in metallic multilayers determined by ferromagnetic resonance measurements of spin pumping
We measured spin transport in nonferromagnetic (NM) metallic multilayers from the contribution to damping due to spin pumping from a ferromagnetic Co90Fe10 thin film. The multilayer stack consisted of NM1/NM2/Co90Fe10(2 nm)/NM2/NM3 with varying NM materials and thicknesses. Using conventional theory for one dimensional...
1301.5861v1
2013-02-11
Low-damping epsilon-near-zero slabs: nonlinear and nonlocal optical properties
We investigate second harmonic generation, low-threshold multistability, all-optical switching, and inherently nonlocal effects due to the free-electron gas pressure in an epsilon-near-zero (ENZ) metamaterial slab made of cylindrical, plasmonic nanoshells illuminated by TM-polarized light. Damping compensation in the E...
1302.2392v1
2013-02-14
A Matlab toolbox for fractional relaxation-oscillation equations
Stress relaxation and oscillation damping of complex viscoelastic media often manifest history- and path-dependent physical behaviors and cannot accurately be described by the classical models. Recent research found that fractional derivative models can characterize such complex relaxation and damping. However, to our ...
1302.3384v1
2013-03-11
The Analysis of Long-Term Frequency and Damping Wandering in Buildings Using the Random Decrement Technique
The characterization and monitoring of buildings is an issue that has attracted the interest of many sectors over the last two decades. With the increasing use of permanent, continuous and real-time networks, ambient vibrations can provide a simple tool for the identification of dynamic building parameters. This study ...
1303.2642v1