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47
2003-03-21
Global well-posedness and multi-tone solutions of a class of nonlinear nonlocal cochlear models in hearing
We study a class of nonlinear nonlocal cochlear models of the transmission line type, describing the motion of basilar membrane (BM) in the cochlea. They are damped dispersive partial differential equations (PDEs) driven by time dependent boundary forcing due to the input sounds. The global well-posedness in time follo...
0303048v1
2004-05-11
Analytical approach to soliton ratchets in asymmetric potentials
We use soliton perturbation theory and collective coordinate ansatz to investigate the mechanism of soliton ratchets in a driven and damped asymmetric double sine-Gordon equation. We show that, at the second order of the perturbation scheme, the soliton internal vibrations can couple {\it effectively}, in presence of d...
0405023v1
2005-02-16
Controlling soliton explosions
We investigate the dynamics of solitons in generalized Klein-Gordon equations in the presence of nonlinear damping and spatiotemporal perturbations. We will present different mechanisms for soliton explosions. We show (both analytically and numerically) that some space-dependent perturbations or nonlinear damping can m...
0502033v1
2005-07-22
Global existence in infinite lattices of nonlinear oscillators: The Discrete Klein-Gordon equation
Pointing out the difference between the Discrete Nonlinear Schr\"odinger equation with the classical power law nonlinearity-for which solutions exist globally, independently of the sign and the degree of the nonlinearity, the size of the initial data and the dimension of the lattice-we prove either global existence or ...
0507044v5
1992-12-14
Poisson and Porter-Thomas Fluctuations in off-Yrast Rotational Transitions
Fluctuations associated with stretched E2 transitions from high spin levels in nuclei around $^{168}$Yb are investigated by a cranked shell model extended to include residual two-body interactions. It is found that the gamma-ray energies behave like random variables and the energy spectra show the Poisson fluctuation, ...
9212006v1
1993-11-25
Microscopic analysis of two-body correlations in light nuclei
Within a nonperturbative dynamical two-body approach - based on coupled equations of motion for the one-body density matrix and the two-body correlation function - we study the distribution of occupation numbers in a correlated system close to the groundstate, the relaxation of single-particle excitations and the dampi...
9311031v1
1997-03-26
A self-consistent treatment of damped motion for stable and unstable collective modes
We address the dynamics of damped collective modes in terms of first and second moments. The modes are introduced in a self-consistent fashion with the help of a suitable application of linear response theory. Quantum effects in the fluctuations are governed by diffusion coefficients D_{\mu\nu}. The latter are obtained...
9703056v1
1997-04-24
A Simple Mode on a Highly Excited Background: Collective Strength and Damping in the Continuum
Simple states, such as isobaric analog states or giant resonances, embedded into continuum are typical for mesoscopic many-body quantum systems. Due to the coupling to compound states in the same energy range, a simple mode acquires a damping width ("internal" dynamics). When studied experimentally with the aid of vari...
9704055v1
1998-10-12
Response function beyond mean field of neutron-rich nuclei
The damping of single-particle and collective motion in exotic isotopes is a new topic and its study may shed light on basic problems of nuclear dynamics. For instance, it is known that nuclear structure calculations are not able, as a rule, to account completely for the empirical single-particle damping. In this contr...
9810033v1
1999-04-14
Scaling Analysis of Fluctuating Strength Function
We propose a new method to analyze fluctuations in the strength function phenomena in highly excited nuclei. Extending the method of multifractal analysis to the cases where the strength fluctuations do not obey power scaling laws, we introduce a new measure of fluctuation, called the local scaling dimension, which cha...
9904037v1
1999-07-07
Pair creation: back-reactions and damping
We solve the quantum Vlasov equation for fermions and bosons, incorporating spontaneous pair creation in the presence of back-reactions and collisions. Pair creation is initiated by an external impulse field and the source term is non-Markovian. A simultaneous solution of Maxwell's equation in the presence of feedback ...
9907027v1
2000-10-23
Barrier penetration and rotational damping of thermally excited superdeformed nuclei
We construct a microscopic model of thermally excited superdeformed states that describes both the barrier penetration mechanism, leading to the decay-out transitions to normal deformed states, and the rotational damping causing fragmentation of rotational E2 transitions. We describe the barrier penetration by means of...
0010074v1
1996-02-22
Stability of Travelling Waves for a Damped Hyperbolic Equation
We consider a nonlinear damped hyperbolic equation in $\real^n$, $1 \le n \le 4$, depending on a positive parameter $\epsilon$. If we set $\epsilon=0$, this equation reduces to the well-known Kolmogorov-Petrovski-Piskunov equation. We remark that, after a change of variables, this hyperbolic equation has the same famil...
9602004v1
1998-09-18
Stability of Propagating Fronts in Damped Hyperbolic Equations
We consider the damped hyperbolic equation in one space dimension $\epsilon u_{tt} + u_t = u_{xx} + F(u)$, where $\epsilon$ is a positive, not necessarily small parameter. We assume that $F(0)=F(1)=0$ and that $F$ is concave on the interval $[0,1]$. Under these assumptions, our equation has a continuous family of monot...
9809007v1
1999-05-28
Existence threshold for the ac-driven damped nonlinear Schrödinger solitons
It has been known for some time that solitons of the externally driven, damped nonlinear Schr\"odinger equation can only exist if the driver's strength, $h$, exceeds approximately $(2/ \pi) \gamma$, where $\gamma$ is the dissipation coefficient. Although this perturbative result was expected to be correct only to the l...
9906001v1
1996-10-01
Exact time evolution and master equations for the damped harmonic oscillator
Using the exact path integral solution for the damped harmonic oscillator it is shown that in general there does not exist an exact dissipative Liouville operator describing the dynamics of the oscillator for arbitrary initial bath preparations. Exact non-stationary Liouville operators can be found only for particular ...
9610001v1
1999-01-09
Cluster ionization via two-plasmon excitation
We calculate the two-photon ionization of clusters for photon energies near the surface plasmon resonance. The results are expressed in terms of the ionization rate of a double plasmon excitation, which is calculated perturbatively. For the conditions of the experiment by Schlipper et al., we find an ionization rate of...
9901008v1
2000-08-01
Rectangular Waveguide HOM Couplers for a TESLA Superstructure
Some modifications of a Rectangular Waveguide HOM couplers for TESLA superstructure have been investigated. These RWG HOM couplers are to be installed between the cavities of the superstructure and also at the both ends of it. We investigated a RWG HOM coupler attached to the beam pipe through the slots orientated alon...
0008001v1
2000-08-17
Superconducting Superstructure for the TESLA Collider: New Results
A new cavity-chain layout has been proposed for the main linac of the TESLA linear collider. This superstructure-layout is based upon four 7-cell superconducting standing-wave cavities, coupled by short beam pipes. The main advantages of the superstructure are an increase in the active accelerating length in TESLA and ...
0008104v1
2000-08-20
An Investigation of Optimised Frequency Distributions for Damping Wakefields in X-Band Linacs for the NLC
In the NLC (Next Linear Collider) small misalignments in each of the individual accelerator structures (or the accelerator cells) will give rise to wakefields which kick the beam from its electrical axis. This wakefield can cause BBU (Beam Break Up) or at the very least it will dilute the emittance of the beam. Several...
0008202v2
2001-04-14
Parameters for a 30 GeV Undulator Test Facility in the FFTB/LCLS
The parameters for a 30 GeV test beam are outlined for use with an undulator in the FFTB tunnel where the LCLS will eventually be housed. It is proposed to use the SLAC linac and damping rings in their present mode of operation for PEP II injection, where 30 GeV beams are also delivered at 10 Hz to the FFTB. High peak ...
0104045v1
2001-10-05
Characterization of a Low Frequency Power Spectral Density f^(-gamma) in a Threshold Model
his study investigates the modifications of the thermal spectrum, at low frequency, induced by an external damping on a system in heat contact with internal fluctuating impurities. Those impurities can move among locations and their oscillations are associated with a loss function depending on the model. The fluctuatio...
0110019v1
2002-05-13
Damping of electromagnetic waves in low-collision electron-ion plasmas
Using previously developed method of two-dimensional Laplace transform we obtain the characteristic equations k(\omega) for electromagnetic waves in low-collision fully ionized plasma of a plane geometry. We apply here a new, different from the one used in our previous paper, iteration procedure of taking into account ...
0205035v2
2002-06-01
Intrabeam scattering analysis of measurements at KEK's ATF damping ring
We derive a simple relation for estimating the relative emittance growth in x and y due to intrabeam scattering (IBS) in electron storage rings. We show that IBS calculations for the ATF damping ring, when using the formalism of Bjorken-Mtingwa, a modified formalism of Piwinski (where eta squared divided by beta has be...
0206003v1
2002-08-24
Wakefield Band Partitioning In Linac Structures
In the NLC project multiple bunches of electrons and positrons will be accelerated initially to a centre of mass of 500 GeV and later to 1 TeV or more. In the process of accelerating 192 bunches within a pulse train, wakefields are excited which kick the trailing bunches off axis and can cause luminosity dilution and B...
0208086v1
2003-01-30
Calculation of the Coherent Synchrotron Radiation Impedance from a Wiggler
Most studies of Coherent Synchrotron Radiation (CSR) have only considered the radiation from independent dipole magnets. However, in the damping rings of future linear colliders, a large fraction of the radiation power will be emitted in damping wigglers. In this paper, the longitudinal wakefield and impedance due to C...
0301073v1
2003-10-02
Damping factors for the gap-tooth scheme
An important class of problems exhibits macroscopically smooth behaviour in space and time, while only a microscopic evolution law is known. For such time-dependent multi-scale problems, the gap-tooth scheme has recently been proposed. The scheme approximates the evolution of an unavailable (in closed form) macroscopic...
0310014v1
2004-07-31
Propagation of optical excitations by dipolar interactions in metal nanoparticle chains
Dispersion relations for dipolar modes propagating along a chain of metal nanoparticles are calculated by solving the full Maxwell equations, including radiation damping. The nanoparticles are treated as point dipoles, which means the results are valid only for a/d <= 1/3, where a is the particle radius and d the spaci...
0408003v2
2004-08-22
Tacoma Bridge Failure-- a Physical Model
The cause of the collapse of the Tacoma Narrows Bridge has been a topic of much debate and confusion since the day it fell. Many mischaracterizations of the observed phenomena have limited the widespread understanding of the problem. Nevertheless, there has always been an abundance of evidence in favour of a negative d...
0408101v1
2004-08-30
Short waves and cyclotron losses in the relativistic gyrokinetic theory
Radiation damping of the motion of charged particles in relativistic, optically thin plasmas is described within the framework of the covariant gyrokinetic theory. It involves description of the collisionless single-particle dynamics as well as the Vlasov and Maxwell equations both written in the covariant formulation....
0408128v1
2004-11-05
Wave-kinetic description of nonlinear photons
The nonlinear interaction, due to quantum electrodynamical (QED) effects, between photons is investigated using a wave-kinetic description. Starting from a coherent wave description, we use the Wigner transform technique to obtain a set of wave-kinetic equations, the so called Wigner-Moyal equations. These equations ar...
0411058v1
2004-12-17
Optimal Determination of the Equilibrium Displacement of a Damped Harmonic Oscillator in the Presence of Thermal Noise
Using a matched filter technique, we derive the minimum variance, unbiased estimator for the equilibrium displacement of a damped harmonic oscillator in thermal equilibrium when interactions with the thermal bath are the leading source of noise. We compare the variance in this optimal estimator with the variance in oth...
0412102v1
2006-01-13
Atomic collider into dual-isotope magneto-optical trap
When two of three pairs of the Gaussian laser beams of a traditional MOT are misaligned in the racetrack configuration the effective coordinate-dependent vortex force do arise. Then an atom is accelerated by this vortex force until its velocity not balanced by the damping force. This situation may produce a stable ring...
0601097v1
2006-12-07
On some peculiarities of electric field pulse propagation in electron Maxwellian plasma and its back response
In the spirit of continued study of general plasma wave properties we investigated the boundary problem with the simplest form of electric field pulse at the edge x=0 of half-infinite uniform plasma slab with Maxwellian electron distribution function. In the case of longitudinal electric field pulse its traveling veloc...
0612064v4
1996-10-29
Bosonic Quantum Codes for Amplitude Damping
Traditional quantum error correction involves the redundant encoding of k quantum bits using n quantum bits to allow the detection and correction of any t bit error. The smallest general t=1 code requires n=5 for k=1. However, the dominant error process in a physical system is often well known, thus inviting the questi...
9610043v1
1997-01-16
Cooperative loss and decoherence in quantum computation and commuication
Cooperative effects in the loss (the amplitude damping) and decoherence (the phase damping) of the qubits (two-state quantum systems) due to the inevitable coupling to the same environment are investigated. It is found that the qubits undergo the dissipation coherently in this case. In particular, for a special kind of...
9701020v1
1997-03-22
Preserving coherence in quantum computation by pairing quantum bits
A scheme is proposed for protecting quantum states from both independent decoherence and cooperative decoherence. The scheme operates by pairing each qubit (two-state quantum system) with an ancilla qubit and by encoding the states of the qubits into the corresponding coherence-preserving states of the qubit-pairs. In ...
9703040v2
1997-06-10
Perturbative expansions for the fidelities and spatially correlated dissipation of quantum bits
We construct generally applicable short-time perturbative expansions for some fidelities, such as the input-output fidelity, the entanglement fidelity, and the average fidelity. Successive terms of these expansions yield characteristic times for the damping of the fidelities involving successive powers of the Hamiltoni...
9706020v2
1998-05-27
Measurement Process In a Two-Barrier System
The description of a measuring process, such as that which occurs when a quantum point contact (QPC) detector is influenced by a nearby external electron which can take up two possible positions, provides a interesting application of the method of quantum damping. We find a number of new effects, due to the complete tr...
9805081v2
1998-10-06
Cumulant expansion for studying damped quantum solitons
The quantum statistics of damped optical solitons is studied using cumulant-expansion techniques. The effect of absorption is described in terms of ordinary Markovian relaxation theory, by coupling the optical field to a continuum of reservoir modes. After introduction of local bosonic field operators and spatial discr...
9810018v3
1999-02-10
Quantum noise in the position measurement of a cavity mirror undergoing Brownian motion
We perform a quantum theoretical calculation of the noise power spectrum for a phase measurement of the light output from a coherently driven optical cavity with a freely moving rear mirror. We examine how the noise resulting from the quantum back action appears among the various contributions from other noise sources....
9902040v1
1999-10-05
Uncertainty, entropy and decoherence of the damped harmonic oscillator in the Lindblad theory of open quantum systems
In the framework of the Lindblad theory for open quantum systems, expressions for the density operator, von Neumann entropy and effective temperature of the damped harmonic oscillator are obtained. The entropy for a state characterized by a Wigner distribution function which is Gaussian in form is found to depend only ...
9910019v1
2000-06-07
Phenomenological approach to introduce damping effects on radiation field states
In this work we propose an approach to deal with radiation field states which incorporates damping effects at zero temperature. By using some well known results on dissipation of a cavity field state, obtained by standard ab-initio methods, it was possible to infer through a phenomenological way the explicit form for t...
0006035v2
2001-09-28
Decoherence in trapped ions due to polarization of the residual background gas
We investigate the mechanism of damping and heating of trapped ions associated with the polarization of the residual background gas induced by the oscillating ions themselves. Reasoning by analogy with the physics of surface electrons in liquid helium, we demonstrate that the decay of Rabi oscillations observed in expe...
0109156v1
2002-06-18
Five Lectures On Dissipative Master Equations
1 First Lecture: Basics 1.1 Physical Derivation of the Master Equation 1.2 Some Simple Implications 1.3 Steady State 1.4 Action to the Left 2 Second Lecture: Eigenvalues and Eigenvectors of L 2.1 A Simple Case First 2.2 The General Case 3 Third Lecture: Completeness of the Damping Bases 3.1 Phase Spac...
0206116v1
2002-10-02
Radiation damping and decoherence in quantum electrodynamics
The processes of radiation damping and decoherence in Quantum Electrodynamics are studied from an open system's point of view. Employing functional techniques of field theory, the degrees of freedom of the radiation field are eliminated to obtain the influence phase functional which describes the reduced dynamics of th...
0210013v1
2003-01-08
Dissipation, Emergent Quantization and Quantum Fluctuations
We review some aspects of the quantization of the damped harmonic oscillator. We derive the exact action for a damped mechanical system in the frame of the path integral formulation of the quantum Brownian motion problem developed by Schwinger and by Feynman and Vernon. The doubling of the phase-space degrees of freedo...
0301031v1
2004-02-12
Non-Markovian Quantum Trajectories Versus Master Equations: Finite Temperature Heat Bath
The interrelationship between the non-Markovian stochastic Schr\"odinger equations and the corresponding non-Markovian master equations is investigated in the finite temperature regimes. We show that the general finite temperature non-Markovian trajectories can be used to derive the corresponding non-Markovian master e...
0402086v2
2005-04-27
Decoherence models and their effects on quantum maps and algorithms
In this work we study several models of decoherence and how different quantum maps and algorithms react when perturbed by them. Following closely Ref. [1], generalizations of the three paradigmatic one single qubit quantum channels (these are the depolarizing channel, the phase damping channel and the amplitude damping...
0504211v1
2005-09-22
Semiclassical quantization of non-Hamiltonian dynamical systems without memory
We propose a new method of quantization of a wide class of dynamical systems that originates directly from the equations of motion. The method is based on the correspondence between the classical and the quantum Poisson brackets, postulated by Dirac. This correspondence applied to open (non-Hamiltonian) systems allows ...
0509159v1
2005-11-15
Classical Phase Space Density for the Relativistic Hydrogen Atom
Quantum mechanics is considered to arise from an underlying classical structure (``hidden variable theory'', ``sub-quantum mechanics''), where quantum fluctuations follow from a physical noise mechanism. The stability of the hydrogen ground state can then arise from a balance between Lorentz damping and energy absorpti...
0511144v1
2006-03-13
Decoherence induced by a phase-damping reservoir
A phase damping reservoir composed by $N$-bosons coupled to a system of interest through a cross-Kerr interaction is proposed and its effects on quantum superpo sitions are investigated. By means of analytical calculations we show that: i-) the reservoir induces a Gaussian decay of quantum coherences, and ii-) the inhe...
0603109v2
2007-01-21
Casimir-Polder forces on excited atoms in the strong atom-field coupling regime
Based on macroscopic quantum electrodynamics in linear media, we develop a general theory of the resonant Casimir-Polder force on an excited two-level atom in the presence of arbitrary linear bodies, with special emphasis on the strong-coupling regime where reabsorption of an emitted photon can give rise to (vacuum) Ra...
0701151v2
2007-02-07
Protecting an optical qubit against photon loss
We consider quantum error-correction codes for multimode bosonic systems, such as optical fields, that are affected by amplitude damping. Such a process is a generalization of an erasure channel. We demonstrate that the most accessible method of transforming optical systems with the help of passive linear networks has ...
0702075v1
1995-02-03
Shock waves in the dissipative Toda lattice
We consider the propagation of a shock wave (SW) in the damped Toda lattice. The SW is a moving boundary between two semi-infinite lattice domains with different densities. A steadily moving SW may exist if the damping in the lattice is represented by an ``inner'' friction, which is a discrete analog of the second visc...
9502001v1
2007-04-04
An integral field spectroscopic survey for high redshift damped Lyman-alpha galaxies
We search for galaxy counterparts to damped Lyman-alpha absorbers (DLAs) at z>2 towards nine quasars, which have 14 DLAs and 8 sub-DLAs in their spectra. We use integral field spectroscopy to search for Ly-alpha emission line objects at the redshifts of the absorption systems. Besides recovering two previously confirme...
0704.0654v1
2007-04-06
9.7 micrometer Silicate Absorption in a Damped Lyman-alpha Absorber at z=0.52
We report a detection of the 9.7 micrometer silicate absorption feature in a damped Lyman-alpha (DLA) system at z_{abs} = 0.524 toward AO0235+164, using the Infrared Spectrograph (IRS) onboard the Spitzer Space Telescope. The feature shows a broad shallow profile over about 8-12 micrometers in the absorber rest frame a...
0704.0826v2
2007-04-17
Boolean network model predicts cell cycle sequence of fission yeast
A Boolean network model of the cell-cycle regulatory network of fission yeast (Schizosaccharomyces Pombe) is constructed solely on the basis of the known biochemical interaction topology. Simulating the model in the computer, faithfully reproduces the known sequence of regulatory activity patterns along the cell cycle ...
0704.2200v1
2007-05-08
Optical dilution and feedback cooling of a gram-scale oscillator to 6.9 mK
We report on use of a radiation pressure induced restoring force, the optical spring effect, to optically dilute the mechanical damping of a 1 gram suspended mirror, which is then cooled by active feedback (cold damping). Optical dilution relaxes the limit on cooling imposed by mechanical losses, allowing the oscillato...
0705.1018v2
2007-05-14
Electron-muon heat conduction in neutron star cores via the exchange of transverse plasmons
We calculate the thermal conductivity of electrons and muons kappa_{e-mu} produced owing to electromagnetic interactions of charged particles in neutron star cores and show that these interactions are dominated by the exchange of transverse plasmons (via the Landau damping of these plasmons in nonsuperconducting matter...
0705.1963v1
2007-05-24
Measurement of Newtonian fluid slip using a torsional ultrasonic oscillator
The composite torsional ultrasonic oscillator, a versatile experimental system, can be used to investigate slip of Newtonian fluid at a smooth surface. A rigorous analysis of slip-dependent damping for the oscillator is presented. Initially, the phenomenon of finite surface slip and the slip length are considered for a...
0705.3498v3
2007-06-05
Waves and instabilities in dissipative rotating superfluid neutron stars
We discuss wave propagation in rotating superfluid neutron star cores, taking into account the vortex mediated mutual friction force. For models where the two fluids co-rotate in the unperturbed state, our analysis clarifies the role of chemical coupling and entrainment for sound and inertial waves. We also investigate...
0706.0672v1
2007-06-28
Coherent Magnetization Precession in GaMnAs induced by Ultrafast Optical Excitation
We use femtosecond optical pulses to induce, control and monitor magnetization precession in ferromagnetic Ga0.965Mn0.035As. At temperatures below ~40 K we observe coherent oscillations of the local Mn spins, triggered by an ultrafast photoinduced reorientation of the in-plane easy axis. The amplitude saturation of the...
0706.4270v2
2007-07-20
Dissipation-Scale Turbulence in the Solar Wind
We present a cascade model for turbulence in weakly collisional plasmas that follows the nonlinear cascade of energy from the large scales of driving in the MHD regime to the small scales of the kinetic Alfven wave regime where the turbulence is dissipated by kinetic processes. Steady-state solutions of the model for t...
0707.3149v1
2007-08-03
Strong spin-orbit induced Gilbert damping and g-shift in iron-platinum nanoparticles
The shape of ferromagnetic resonance spectra of highly dispersed, chemically disordered Fe_{0.2}Pt_{0.8} nanospheres is perfectly described by the solution of the Landau-Lifshitz-Gilbert (LLG) equation excluding effects by crystalline anisotropy and superparamagnetic fluctuations. Upon decreasing temperature, the LLG d...
0708.0463v1
2007-08-09
An algorithm for detecting oscillatory behavior in discretized data: the damped-oscillator oscillator detector
We present a simple algorithm for detecting oscillatory behavior in discrete data. The data is used as an input driving force acting on a set of simulated damped oscillators. By monitoring the energy of the simulated oscillators, we can detect oscillatory behavior in data. In application to in vivo deep brain basal gan...
0708.1341v1
2007-08-22
The dynamics of vortex generation in superfluid 3He-B
A profound change occurs in the stability of quantized vortices in externally applied flow of superfluid 3He-B at temperatures ~ 0.6 Tc, owing to the rapidly decreasing damping in vortex motion with decreasing temperature. At low damping an evolving vortex may become unstable and generate a new independent vortex loop....
0708.3003v2
2007-09-05
Phonon bottleneck in the low-excitation limit
The phonon-bottleneck problem in the relaxation of two-level systems (spins) via direct phonon processes is considered numerically in the weak-excitation limit where the Schroedinger equation for the spin-phonon system simplifies. The solution for the relaxing spin excitation p(t), emitted phonons n_k(t), etc. is obtai...
0709.0556v1
2007-09-13
Distribution of PageRank Mass Among Principle Components of the Web
We study the PageRank mass of principal components in a bow-tie Web Graph, as a function of the damping factor c. Using a singular perturbation approach, we show that the PageRank share of IN and SCC components remains high even for very large values of the damping factor, in spite of the fact that it drops to zero whe...
0709.2016v1
2007-10-02
Oscillating Starless Cores: The Nonlinear Regime
In a previous paper, we modeled the oscillations of a thermally-supported (Bonnor-Ebert) sphere as non-radial, linear perturbations following a standard analysis developed for stellar pulsations. The predicted column density variations and molecular spectral line profiles are similar to those observed in the Bok globul...
0710.0625v1
2007-10-08
Jet quenching parameter \hat q in the stochastic QCD vacuum with Landau damping
We argue that the radiative energy loss of a parton traversing the quark-gluon plasma is determined by Landau damping of soft modes in the plasma. Using this idea, we calculate the jet quenching parameter of a gluon. The calculation is done in SU(3) quenched QCD within the stochastic vacuum model. At the LHC-relevant t...
0710.1540v2
2007-11-07
Tuning the effective coupling of an AFM lever to a thermal bath
Fabrication of Nano-Electro-Mechanical-Systems (NEMS) of high quality is nowadays extremely efficient. These NEMS will be used as sensors and actuators in integrated systems. Their use however raises questions about their interface (actuation, detection, read out) with external detection and control systems. Their oper...
0711.1024v1
2007-12-11
Neutrino oscillations in a stochastic model for space-time foam
We study decoherence models for flavour oscillations in four-dimensional stochastically fluctuating space times and discuss briefly the sensitivity of current neutrino experiments to such models. We pay emphasis on demonstrating the model dependence of the associated decoherence-induced damping coefficients in front of...
0712.1779v1
2008-01-21
Collective cyclotron motion of the relativistic plasma in graphene
We present a theory of the finite temperature thermo-electric response functions of graphene, in the hydrodynamic regime induced by electron-electron collisions. In moderate magnetic fields, the Dirac particles undergo a collective cyclotron motion with a temperature-dependent relativistic cyclotron frequency proportio...
0801.2970v3
2008-01-25
Sound waves and solitons in hot and dense nuclear matter
Assuming that nuclear matter can be treated as a perfect fluid, we study the propagation of perturbations in the baryon density. The equation of state is derived from a relativistic mean field model, which is a variant of the non-linear Walecka model. The expansion of the Euler and continuity equations of relativistic ...
0801.3938v1
2008-01-28
Qualitative Analysis of Forced Response of Blisks With Friction Ring Dampers
A damping strategy for blisks (integrally bladed disks) of turbomachinery involving a friction ring is investigated. These rings, located in grooves underside the wheel of the blisks, are held in contact by centrifugal loads and the energy is dissipated when relative motions between the ring and the disk occur. A repre...
0801.4350v1
2008-01-29
Long Term Evolution of Magnetic Turbulence in Relativistic Collisionless Shocks
We study the long term evolution of magnetic fields generated by an initially unmagnetized collisionless relativistic $e^+e^-$ shock. Our 2D particle-in-cell numerical simulations show that downstream of such a Weibel-mediated shock, particle distributions are approximately isotropic, relativistic Maxwellians, and the ...
0801.4583v1
2008-02-14
Light-induced magnetization precession in GaMnAs
We report dynamics of the transient polar Kerr rotation (KR) and of the transient reflectivity induced by femtosecond laser pulses in ferromagnetic (Ga,Mn)As with no external magnetic field applied. It is shown that the measured KR signal consist of several different contributions, among which only the oscillatory sign...
0802.2043v2
2008-02-20
Mechanical mode dependence of bolometric back-action in an AFM microlever
Two back action (BA) processes generated by an optical cavity based detection device can deeply transform the dynamical behavior of an AFM microlever: the photothermal force or the radiation pressure. Whereas noise damping or amplifying depends on optical cavity response for radiation pressure BA, we present experiment...
0802.2763v2
2008-02-21
Propagation of cosmic rays in the foam-like Universe
The model of a classical spacetime foam is considered, which consists of static wormholes embedded in Minkowski spacetime. We examine the propagation of particles in such a medium and demonstrate that a single thin ray undergoes a specific damping in the density of particles depending on the traversed path and the dist...
0802.3109v2
2008-02-21
Damping by slow relaxing rare earth impurities in Ni80Fe20
Doping NiFe by heavy rare earth atoms alters the magnetic relaxation properties of this material drastically. We show that this effect can be well explained by the slow relaxing impurity mechanism. This process is a consequence of the anisotropy of the on site exchange interaction between the 4f magnetic moments and th...
0802.3206v3
2008-03-11
Domain wall motion of magnetic nanowires under a static field
The propagation of a head-to-head magnetic domain-wall (DW) or a tail-to-tail DW in a magnetic nanowire under a static field along the wire axis is studied. Relationship between the DW velocity and DW structure is obtained from the energy consideration. The role of the energy dissipation in the field-driven DW motion i...
0803.1531v1
2008-03-11
Equation of state for strongly interacting matter: collective effects, Landau damping and predictions for LHC
The equation of state (EOS) is of utmost importance for the description of the hydrodynamic phase of strongly interacting matter in relativistic heavy-ion collisions. Lattice QCD can provide useful information on the EOS, mainly for small net baryon densities. The QCD quasiparticle model provides a means to map lattice...
0803.1571v1
2008-04-04
Spin-charge coupling in a band ferromagnet: magnon-energy reduction, anomalous softening, and damping
The effects of correlation-induced coupling between spin and charge fluctuations on spin-wave excitations in a band ferromagnet are investigated by including self-energy and vertex corrections within a systematic inverse-degeneracy expansion scheme which explicitly preserves the Goldstone mode. Arising from the scatter...
0804.0680v1
2008-05-01
Chaotic Spin Dynamics of a Long Nanomagnet Driven by a Current
We study the spin dynamics of a long nanomagnet driven by an electrical current. In the case of only DC current, the spin dynamics has a sophisticated bifurcation diagram of attractors. One type of attractors is a weak chaos. On the other hand, in the case of only AC current, the spin dynamics has a rather simple bifur...
0805.0147v1
2008-05-07
Noise Analysis and Noise-based Optimization for Resonant MEMS Structures
This paper presents a detailed noise analysis and a noise-based optimization procedure for resonant MEMS structures. A design for high sensitivity of MEMS structures needs to take into account the noise shaping induced by damping phenomena at micro scale. The existing literature presents detailed models for the damping...
0805.0927v1
2008-05-07
Scaling crossovers in activated escape of nonequilibrium systems: a resonantly driven oscillator
The rate of metastable decay in nonequilibrium systems is expected to display scaling behavior: i.e., the logarithm of the decay rate should scale as a power of the distance to a bifurcation point where the metastable state disappears. Recently such behavior was observed and some of the earlier predicted exponents were...
0805.0972v2
2008-05-07
Quantum Noise, Effective Temperature, and Damping in a Superconducting Single-Electron Transistor
We have directly measured the quantum noise of a superconducting single-electron transistor (S-SET) embedded in a microwave resonator consisting of a superconducting LC tank circuit. Using an effective bath description, we find that the S-SET provides damping of the resonator modes proportional to its differential cond...
0805.1037v1
2008-05-08
Adaptive Affinity Propagation Clustering
Affinity propagation clustering (AP) has two limitations: it is hard to know what value of parameter 'preference' can yield an optimal clustering solution, and oscillations cannot be eliminated automatically if occur. The adaptive AP method is proposed to overcome these limitations, including adaptive scanning of prefe...
0805.1096v1
2008-06-06
On the stability of shocks with particle pressure
We perform a linear stability analysis for corrugations of a Newtonian shock, with particle pressure included, for an arbitrary diffusion coefficient. We study first the dispersion relation for homogeneous media, showing that, besides the conventional pressure waves and entropy/vorticity disturbances, two new perturbat...
0806.1113v1
2008-06-17
Damping of Fast Magnetohydrodynamic Oscillations in Quiescent Filament Threads
High-resolution observations provide evidence about the existence of small-amplitude transverse oscillations in solar filament fine structures. These oscillations are believed to represent fast magnetohydrodynamic (MHD) waves and the disturbances are seen to be damped in short timescales of the order of 1 to 4 periods....
0806.2728v1
2008-06-27
Global attractor and asymptotic smoothing effects for the weakly damped cubic Schrödinger equation in $L^2(\T)$
We prove that the weakly damped cubic Schr\"odinger flow in $L^2(\T)$ provides a dynamical system that possesses a global attractor. The proof relies on a sharp study of the behavior of the associated flow-map with respect to the weak $ L^2(\T) $-convergence inspired by a previous work of the author. Combining the comp...
0806.4578v3
2008-06-30
Thermal depinning of fluxons in discrete Josephson rings
We study the thermal depinning of single fluxons in rings made of Josephson junctions. Due to thermal fluctuations a fluxon can be excited from its energy minima and move through the array, causing a voltage across each junction. We find that for the initial depinning, the fluxon behaves as a single particle and follow...
0806.4828v1
2008-07-03
Dependence of the decoherence of polarization states in phase-damping channels on the frequency spectrum envelope of photons
We consider the decoherence of photons suffering in phase-damping channels. By exploring the evolutions of single-photon polarization states and two-photon polarization-entangled states, we find that different frequency spectrum envelopes of photons induce different decoherence processes. A white frequency spectrum can...
0807.0536v3
2008-07-17
Planetary Migration in Resonance, the question of the Eccentricities : Les Houches contribution
The formation of resonant planets pairs in exoplanetary systems involves planetary migration inside the protoplanetary disc : an inwards migrating outer planet captures in Mean Motion Resonance an inner planet. During the migration of the resonant pair of planets, the eccentricities are expected to rise excessively, if...
0807.2828v2
2008-07-18
Heavily Damped Motion of One-Dimensional Bose Gases in an Optical Lattice
We study the dynamics of strongly correlated one-dimensional Bose gases in a combined harmonic and optical lattice potential subjected to sudden displacement of the confining potential. Using the time-evolving block decimation method, we perform a first-principles quantum many-body simulation of the experiment of Ferti...
0807.2898v2
2008-07-21
Mutual friction in a cold color flavor locked superfluid and r-mode instabilities in compact stars
Dissipative processes acting in rotating neutron stars are essential in preventing the growth of the r-mode instability. We estimate the damping time of r-modes of an hypothetical compact quark star made up by color flavor locked quark matter at a temperature $T \lesssim 0.01$ MeV. The dissipation that we consider is d...
0807.3264v2
2008-07-23
Dynamical Backaction of Microwave Fields on a Nanomechanical Oscillator
We measure the response and thermal motion of a high-Q nanomechanical oscillator coupled to a superconducting microwave cavity in the resolved-sideband regime where the oscillator's resonance frequency exceeds the cavity's linewidth. The coupling between the microwave field and mechanical motion is strong enough for ra...
0807.3585v3
2008-07-28
Shear Viscosity of the outer crust of Neutron stars: Ion Contribution
The shear viscosity of the crust might have a damping effect on the amplitude of r-modes of rotating neutron stars. This damping has implications for the emission of gravitational waves. We calculate the contribution to the shear viscosity coming from the ions using both semi-analytical methods, that consider binary co...
0807.4353v2
2008-07-28
Unusual decoherence in qubit measurements with a Bose-Einstein condensate
We consider an electrostatic qubit located near a Bose-Einstein condensate (BEC) of noninteracting bosons in a double-well potential, which is used for qubit measurements. Tracing out the BEC variables we obtain a simple analytical expression for the qubit's density-matrix. The qubit's evolution exhibits a slow ($\prop...
0807.4440v2