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2011-08-02
PHENIX Measurements of Higher-order Flow Harmonics in Au+Au collisions at Root_s = 200 GeV
Flow coefficients $v_n$ for $n$ = 2, 3, 4, characterizing the anisotropic collective flow in Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV, are presented. They indicate the expected growth of viscous damping for sound propagation in the quark gluon plasma (QGP) produced in these collisions. Hydrodynamical model compari...
1108.0457v1
2011-08-10
Critical exponents of steady-state phase transitions in fermionic lattice models
We discuss reservoir induced phase transitions of lattice fermions in the non-equilibrium steady state (NESS) of an open system with local reservoirs. These systems may become critical in the sense of a diverging correlation length upon changing the reservoir coupling. We here show that the transition to a critical sta...
1108.2263v5
2011-09-09
Observation of Spontaneous Brillouin Cooling
While radiation-pressure cooling is well known, the Brillouin scattering of light from sound is considered an acousto-optical amplification-only process. It was suggested that cooling could be possible in multi-resonance Brillouin systems when phonons experience lower damping than light. However, this regime was not ac...
1109.2084v2
2011-09-14
Oscillations of simple networks
To describe the flow of a miscible quantity on a network, we introduce the graph wave equation where the standard continuous Laplacian is replaced by the graph Laplacian. This is a natural description of an array of inductances and capacities, of fluid flow in a network of ducts and of a system of masses and springs. T...
1109.3071v2
2011-09-21
High-order explicit local time-stepping methods for damped wave equations
Locally refined meshes impose severe stability constraints on explicit time-stepping methods for the numerical simulation of time dependent wave phenomena. Local time-stepping methods overcome that bottleneck by using smaller time-steps precisely where the smallest elements in the mesh are located. Starting from classi...
1109.4480v2
2011-09-21
Anisotropic critical magnetic fluctuations in the ferromagnetic superconductor UCoGe
We report neutron scattering measurements of critical magnetic excitations in the weakly ferromagnetic superconductor UCoGe. The strong non-Landau damping of the excitations we observe, although unusual has been found in another related ferromagnet, UGe2 at zero pressure. However, we also find there is a significant an...
1109.4541v1
2011-09-30
PT-symmetry, indefinite damping and dissipation-induced instabilities
With perfectly balanced gain and loss, dynamical systems with indefinite damping can obey the exact PT-symmetry being marginally stable with a pure imaginary spectrum. At an exceptional point where the symmetry is spontaneously broken, the stability is lost via passing through a non-semisimple 1:1 resonance. In the par...
1110.0018v2
2011-10-01
Electrical measurement of antivortex wall eigenfrequency
The dynamics of a ferromagnetic antivortex wall has been experimentally studied in a magnetic nanostructure. Two different techniques have been used to independently measure the eigenfrequency of an antivortex wall such as the resonance excitation by sinusoidal microwave and the damped resonance excitation induced by s...
1110.0113v1
2011-10-06
Comparative Wakefield Analysis of a First Prototype of a DDS Structure for CLIC Main Linac
A Damped Detuned Structure (DDS) for CLIC main linac has been proposed as an alternative to the present baseline design which is based on heavy damping. A first prototype, CLIC_DDS_A, for high power tests has been already designed and is under construction. It is also foreseen to design a further prototype, CLIC_DDS_B,...
1110.1207v1
2011-10-12
Nonlinear dynamic analysis of an optimal particle damper
We study the dynamical behavior of a single degree of freedom mechanical system with a particle damper. The particle (granular) damping was optimized for the primary system operating condition by using an appropriate gap size for a prismatic enclosure. The particles absorb the kinetic energy of the vibrating structure ...
1110.2800v1
2011-10-14
Effect of Compton Scattering on the Electron Beam Dynamics at the ATF Damping Ring
Compton scattering provides one of the most promising scheme to obtain polarized positrons for the next generation of $e^-$ -- $e^+$ colliders. Moreover it is an attractive method to produce monochromatic high energy polarized gammas for nuclear applications and X-rays for compact light sources. In this framework a fou...
1110.3241v1
2011-10-15
Atomistic spin dynamic method with both damping and moment of inertia effects included from first principles
We consider spin dynamics for implementation in an atomistic framework and we address the feasibility of capturing processes in the femtosecond regime by inclusion of moment of inertia. In the spirit of an {\it s-d} -like interaction between the magnetization and electron spin, we derive a generalized equation of motio...
1110.3387v2
2011-10-24
CoB/Ni-Based Multilayer Nanowire with High-Speed Domain Wall Motion under Low Current Control
The spin-transfer torque motion of magnetic domain walls (DWs) in a CoB/Ni-based nanowire driven by a low current density of (1.12\pm0.8)\times10^{11} A m^{-2} has been observed indirectly by magnetotransport measurements. A high DW velocity of 85\pm4 m/s at zero field was measured at the threshold current density. Upo...
1110.5112v3
2011-10-28
Stability of linear and non-linear lambda and tripod systems in the presence of amplitude damping
We present the stability analysis of the dark states in the adiabatic passage for the linear and non-linear lambda and tripod systems in the presence of amplitude damping (losses). We perform an analytic evaluation of the real parts of eigenvalues of the corresponding Jacobians, the non-zero eigenvalues of which are fo...
1110.6379v2
2011-11-07
Control of Material Damping in High-Q Membrane Microresonators
We study the mechanical quality factors of bilayer aluminum/silicon-nitride membranes. By coating ultrahigh-Q Si3N4 membranes with a more lossy metal, we can precisely measure the effect of material loss on Q's of tensioned resonator modes over a large range of frequencies. We develop a theoretical model that interpret...
1111.1703v2
2011-11-15
Thermodynamic anomaly of the free damped quantum particle: the bath perspective
A possible definition of the specific heat of open quantum systems is based on the reduced partition function of the system. For a free damped quantum particle, it has been found that under certain conditions, this specific heat can become negative at low temperatures. In contrast to the conventional approaches focusin...
1111.3594v2
2011-12-02
On the propagation of binary signals in damped mechanical systems of oscillators
In the present work, we explore efficient ways to transmit binary information in discrete, semi-infinite chains of coupled oscillators using the process of nonlinear supratransmission. A previous work showed that such transmission is possible and, indeed, reliable under the idealistic condition when weak or no damping ...
1112.0585v1
2011-12-02
On the simulation of the energy transmission in the forbidden band-gap of a spatially discrete double sine-Gordon system
In this work, we present a numerical method to consistently approximate solutions of a spatially discrete, double sine-Gordon chain which considers the presence of external damping. In addition to the finite-difference scheme employed to approximate the solution of the difference-differential equations of the model und...
1112.0595v1
2011-12-11
Spin-polarized current effect on antiferromagnet magnetization in a ferromagnet - antiferromagnet nanojunction: Theory and simulation
Spin-polarized current effect is studied on the static and dynamic magnetization of the antiferromagnet in a ferromagnet - antiferromagnet nanojunction. The macrospin approximation is generalized to antiferromagnets. Canted antiferromagnetic configuration and resulting magnetic moment are induced by an external magneti...
1112.2362v1
2011-12-15
Analytic gas orbits in an arbitrary rotating galactic potential using the linear epicyclic approximation
A code, Epic5, has been developed which computes, in the two-dimensional case, the initially circular orbits of guiding centra in an arbitrary axisymmetric potential with an arbitrary, weak perturbing potential in solid body rotation. This perturbing potential is given by its Fourier expansion. The analytic solution so...
1112.3658v1
2011-12-23
Temperature gradient assisted magnetodynamics in a ferromagnetic nanowire
The dynamics of the low energy excitations in a ferromagnet is studied in case a temperature gradient is coupled to the local magnetization. Due to the different time scales of changing temperature and magnetization it is argued that only the coupling between the spatially varying part of the temperature field and the ...
1112.5562v1
2012-01-04
A new candidate for probing Population III nucleosynthesis with carbon-enhanced damped Lyman-alpha systems
We report the identification of a very metal-poor damped Lyman-alpha system (DLA) at z_abs = 3.067295 that is modestly carbon-enhanced, with an iron abundance of ~1/700 solar ([Fe/H] = -2.84) and [C,O/Fe] ~ +0.6. Such an abundance pattern is likely to be the result of nucleosynthesis by massive stars. On the basis of 1...
1201.1004v2
2012-01-06
Magnetic field decay with Hall drift in neutron star crusts
The dynamics of magnetic field decay with Hall drift is investigated. Assuming that axisymmetric magnetic fields are located in a spherical crust with uniform conductivity and electron number density, long-term evolution is calculated up to Ohmic dissipation. The nonlinear coupling between poloidal and toroidal compone...
1201.1346v1
2012-01-06
Reversible Dissipative Processes, Conformal Motions and Landau Damping
The existence of a dissipative flux vector is known to be compatible with reversible processes, provided a timelike conformal Killing vector (CKV) $\chi^\alpha=\frac{V^\alpha}{T}$ (where $V^\alpha$ and $T$ denote the four-velocity and temperature respectively) is admitted by the space-time. Here we show that if a const...
1201.1390v1
2012-01-19
Wave Leakage and Resonant Absorption in a Loop Embedded in a Coronal Arcade
We investigate the temporal evolution of impulsively generated perturbations in a potential coronal arcade with an embedded loop. As the initial configuration we consider a coronal loop, represented by a density enhancement, which is unbounded in the ignorable direction of the arcade. The linearized time-dependent magn...
1201.4042v1
2012-02-08
Evidence of Wave Damping at Low Heights in a Polar Coronal Hole
We have measured the widths of spectral lines from a polar coronal hole using the Extreme Ultraviolet Imaging Spectrometer onboard Hinode. Polar coronal holes are regions of open magnetic field and the source of the fast solar wind. We find that the line widths decrease at relatively low heights. Previous observations ...
1202.1743v2
2012-02-14
The kinetic temperature in a damped Lyman-alpha absorption system in Q2206-199 - an example of the warm neutral medium
By comparing the widths of absorption lines from OI, SiII and FeII in the redshift z=2.076 single-component damped Lyman alpha absorption system in the spectrum of Q2206-199 we establish that these absorption lines arise in Warm Neutral Medium gas at ~12000 +/- 3000K. This is consistent with thermal equilibrium model e...
1202.3012v1
2012-02-23
Eigenmodes of the damped wave equation and small hyperbolic subsets
We study stationary solutions of the damped wave equation on a compact and smooth Riemannian manifold without boundary. In the high frequency limit, we prove that a sequence of $\beta$-damped stationary solutions cannot be completely concentrated in small neighborhoods of a small fixed hyperbolic subset made of $\beta$...
1202.5123v3
2012-03-04
Dissipation effects in random transverse-field Ising chains
We study the effects of Ohmic, super-Ohmic, and sub-Ohmic dissipation on the zero-temperature quantum phase transition in the random transverse-field Ising chain by means of an (asymptotically exact) analytical strong-disorder renormalization-group approach. We find that Ohmic damping destabilizes the infinite-randomne...
1203.0698v2
2012-03-22
Large Amplitude Longitudinal Oscillations in a Solar Filament
We have developed the first self-consistent model for the observed large-amplitude oscillations along filament axes that explains the restoring force and damping mechanism. We have investigated the oscillations of multiple threads formed in long, dipped flux tubes through the thermal nonequilibrium process, and found t...
1203.5027v1
2012-03-26
Analysis of the Energy Decay of a Degenerated Thermoelasticity System
In this paper, we study a system of thermoelasticity with a degenerated second order operator in the Heat equation. We analyze the evolution of the energy density of a family of solutions. We consider two cases: when the set of points where the ellipticity of the Heat operator fails is included in a hypersurface and wh...
1203.5606v1
2012-03-26
Infinite Energy Solutions for Damped Navier-Stokes Equations in R2
We study the so-called damped Navier-Stokes equations in the whole 2D space. The global well-posedness, dissipativity and further regularity of weak solutions of this problem in the uniformly-local spaces are verified based on the further development of the weighted energy theory for the Navier-Stokes type problems. No...
1203.5733v2
2012-03-28
Quantum-correlating power of local quantum channels
Quantum correlation can be created by local operations from a classically correlated state. We define quantum-correlating power (QCP) of a local quantum channel as the maximum amount of quantum correlation that can be created by the channel. The quantum correlation that we discuss in this article is defined on the left...
1203.6149v1
2012-04-12
On the sizes of z>2 Damped Lyman-alpha Absorbing Galaxies
Recently, the number of detected galaxy counterparts of z > 2 Damped Lyman-alpha Absorbers in QSO spectra has increased substantially so that we today have a sample of 10 detections. M{\o}ller et al. in 2004 made the prediction, based on a hint of a luminosity-metallicity relation for DLAs, that HI size should increase...
1204.2833v1
2012-04-16
Quasi-normal modes, area spectra and multi-horizon spacetimes
We suggest an interpretation for the highly damped QNM frequencies of the spherically symmetric multi-horizon spacetimes (Reissner-Nordstrom, Schwarzschild-deSitter, Reissner-Nordstrom-deSitter) following Maggiore's proposal about the link between the asymptotic QNM frequencies and the black hole thermodynamics. We sho...
1204.3566v2
2012-05-03
Explicit local time-stepping methods for time-dependent wave propagation
Semi-discrete Galerkin formulations of transient wave equations, either with conforming or discontinuous Galerkin finite element discretizations, typically lead to large systems of ordinary differential equations. When explicit time integration is used, the time-step is constrained by the smallest elements in the mesh ...
1205.0654v2
2012-05-15
Molecular vibrations-induced quantum beats in two-dimensional electronic spectroscopy
Quantum beats in nonlinear spectroscopy of molecular aggregates are often attributed to electronic phenomena of excitonic systems, while nuclear degrees of freedom are commonly included into models as overdamped oscillations of bath constituents responsible for dephasing. However, molecular systems are coupled to vario...
1205.3383v2
2012-05-16
Deuterium at high-redshift: Primordial abundance in the zabs = 2.621 damped Ly-alpha system towards CTQ247
The detection of neutral deuterium in the low-metallicity damped Lyman-{\alpha} system at zabs = 2.621 towards the quasar CTQ247 is reported. Using a high signal-to-noise and high spectral resolution (R = 60000) spectrum from the Very Large Telescope Ultraviolet and Visual Echelle Spectrograph, we precisely measure the...
1205.3777v1
2012-05-23
Global existence for a damped wave equation and convergence towards a solution of the Navier-Stokes problem
In two and three space dimensions, and under suitable assumptions on the initial data, we show global existence for a damped wave equation which approaches, in some sense, the Navier-Stokes problem. The proofs are based on a refined energy method. In this paper, we improve the results in two papers by Y. Brenier, R. Na...
1205.5166v2
2012-05-24
Modelling the Propagation of a Weak Fast-Mode MHD Shock Wave near a 2D Magnetic Null Point Using Nonlinear Geometrical Acoustics
We present the results of analytical modelling of fast-mode magnetohydrodynamic wave propagation near a 2D magnetic null point. We consider both a linear wave and a weak shock and analyse their behaviour in cold and warm plasmas. We apply the nonlinear geometrical acoustics method based on the Wentzel-Kramers-Brillouin...
1205.5327v1
2012-05-31
Quasinormal modes for the scattering on a naked Reissner-Nordstrom singularity
What should be the quasinormal modes associated with a spacetime that contains a naked singularity instead of a black hole? In the present work we address this problem by studying the scattering of scalar fields on a curved background described by a Reissner-Nordstr\"om spacetime with $|q| > m$. We show that there is a...
1206.0037v3
2012-06-06
Perturbation theory for very long-range potentials
Systems with very long-range interactions (that decay at large distances like $U(r)\sim r^{-l}$ with $l\le d$ where $d$ is the space dimensionality) are difficult to study by conventional statistical mechanics perturbation methods. Examples of these systems are gravitational and charged (non-electroneutral). In this wo...
1206.2211v2
2012-06-10
Comments on "Plasma oscillations and nonextensive statistics"
The paper, authored by J. A. S. Lima et al, was published in Phys. Rev. E in 2000 has discussed the dispersion relation and Landau damping of Langmuir wave in the context of the nonextensive statistics proposed by Tsallis. It has been cited by many authors because the dispersion relation in Tsallis formalism present a ...
1206.2345v1
2012-06-25
Ideal MHD Ballooning modes, shear flow and the stable continuum
There is a well established theory of Ballooning modes in a toroidal plasma. The cornerstone of this is a local eigenvalue lambda on each magnetic surface - which also depends on the ballooning phase angle k. In stationary plasmas lambda(k) is required only near its maximum, but in rotating plasmas its average over k i...
1206.5855v2
2012-06-26
A Numerical Perspective on Hartree-Fock-Bogoliubov Theory
The method of choice for describing attractive quantum systems is Hartree-Fock-Bogoliubov (HFB) theory. This is a nonlinear model which allows for the description of pairing effects, the main explanation for the superconductivity of certain materials at very low temperature. This paper is the first study of Hartree-Foc...
1206.6081v1
2012-06-27
Dynamics of zonal flow-like structures in the edge of the TJ-II stellarator
The dynamics of fluctuating electric field structures in the edge of the TJ-II stellarator, that display zonal flow-like traits, is studied. These structures have been shown to be global and affect particle transport dynamically [J.A. Alonso et al., Nucl. Fus. 52 063010 (2012)]. In this article we discuss possible driv...
1206.6191v1
2012-07-13
Decay of capillary wave turbulence
We report on the observation of freely decaying capillary wave turbulence on the surface of a fluid. The capillary wave turbulence spectrum decay is found to be self-similar in time with the same power law exponent than the one found in the stationary regime, in agreement with weak turbulence predictions. The amplitude...
1207.3228v1
2012-07-17
Holographic Superfluids and the Dynamics of Symmetry Breaking
We explore the far from equilibrium response of a holographic superfluid using the AdS/CFT correspondence. We establish the dynamical phase diagram corresponding to quantum quenches of the order parameter source field. We find three distinct regimes of behaviour that are related to the spectrum of black hole quasi-norm...
1207.4194v2
2012-07-26
Generic Mechanism of Optimal Energy Transfer Efficiency: A Scaling Theory of the Mean First Passage Time in Exciton Systems
An asymptotic scaling theory is presented using the conceptual basis of trapping-free subspace (i.e., orthogonal subspace) to establish the generic mechanism of optimal efficiency of excitation energy transfer (EET) in light-harvesting systems. Analogous to Kramers' turnover in classical rate theory, the enhanced effic...
1207.6197v1
2012-07-27
Dissipative and Non-dissipative Single-Qubit Channels: Dynamics and Geometry
Single-qubit channels are studied under two broad classes: amplitude damping channels and generalized depolarizing channels. A canonical derivation of the Kraus representation of the former, via the Choi isomorphism is presented for the general case of a system's interaction with a squeezed thermal bath. This isomorphi...
1207.6519v1
2012-07-27
Phonon Effects on Population Inversion in Quantum Dots: Resonant, Detuned and Frequency-swept Excitations
The effect of acoustic phonons on different light-induced excitations of a semiconductor quantum dot is investigated. Resonant excitation of the quantum dot leads to Rabi oscillations, which are damped due to the phonon interaction. When the excitation frequency is detuned, an occupation can only occur due to phonon ab...
1207.6660v2
2012-07-28
Ultrafast optical control of magnetization in EuO thin films
All-optical pump-probe detection of magnetization precession has been performed for ferromagnetic EuO thin films at 10 K. We demonstrate that the circularly-polarized light can be used to control the magnetization precession on an ultrafast time scale. This takes place within the 100 fs duration of a single laser pulse...
1207.6686v1
2012-08-07
Observation of Coherent Helimagnons and Gilbert damping in an Itinerant Magnet
We study the magnetic excitations of itinerant helimagnets by applying time-resolved optical spectroscopy to Fe0.8Co0.2Si. Optically excited oscillations of the magnetization in the helical state are found to disperse to lower frequency as the applied magnetic field is increased; the fingerprint of collective modes uni...
1208.1462v1
2012-08-08
Mechanism of collisionless sound damping in dilute Bose gas with condensate
We develop a microscopic theory of sound damping due to Landau mechanism in dilute gas with Bose condensate. It is based on the coupled evolution equations of the parameters describing the system. These equations have been derived in earlier works within a microscopic approach which employs the Peletminskii-Yatsenko re...
1208.1653v2
2012-08-17
Detection of domain wall eigenfrequency in infinity-shaped magnetic nanostructures
The dynamics of a magnetic infinity-shaped nanostructure has been experimentally studied by two different techniques such as the sinusoidal resonance excitation and the damped short pulse excitation to measure the eigenfrequency of domain walls. Direct observation of the magnetic domain wall nucleation has been measure...
1208.3527v1
2012-08-21
Stress field and spin axis relaxation for inelastic triaxial ellipsoids
A compact formula for the stress tensor inside a self-gravitating, triaxial ellipsoid in an arbitrary rotation state is given. It contains no singularity in the incompressible medium limit. The stress tensor and the quality factor model are used to derive a solution for the energy dissipation resulting in the damping (...
1208.4283v2
2012-08-22
On unorthodox solutions of the Bloch equations
A systematic, rigorous, and complete investigation of the Bloch equations in time-harmonic driving classical field is performed. Our treatment is unique in that it takes full advantage of the partial fraction decomposition over real number field, which makes it possible to find and classify all analytic solutions. Torr...
1208.5736v1
2012-08-29
Optically mediated nonlinear quantum optomechanics
We consider theoretically the optomechanical interaction of several mechanical modes with a single quantized cavity field mode for linear and quadratic coupling. We focus specifically on situations where the optical dissipation is the dominant source of damping, in which case the optical field can be adiabatically elim...
1208.5821v1
2012-08-31
Spectrums of Black Hole in de Sitter Spacetime with Highly Damped Quasinormal Modes: High Overtone Case
Motivated by recent physical interpretation on quasinormal modes presented by Maggiore, the adiabatic quantity method given by Kunstatter is used to calculate the spectrums of a non-extremal Schwarzschild de Sitter black hole in this paper, as well as electrically charged case. According to highly damped Konoplya and Z...
1208.6485v1
2012-09-10
Rapid ramps across the BEC-BCS crossover: a novel route to measuring the superfluid gap
We investigate the response of superfluid Fermi gases to rapid changes of the three-dimensional s-wave scattering length a by solving the time-dependent Bogoliubov-de Gennes equations. In general the magnitude of the order parameter |\Delta| performs oscillations, which are sometimes called the "Higgs" mode, with the a...
1209.2025v1
2012-09-12
Loss of Landau Damping for Bunch Oscillations
Conditions for the existence, uniqueness and stability of self-consistent bunch steady states are considered. For the existence and uniqueness problems, simple algebraic criteria are derived for both the action and Hamiltonian domain distributions. For the stability problem, van Kampen theory is used. The onset of a di...
1209.2715v1
2012-09-17
Generalized fluctuation-dissipation relation and statistics for the equilibrium of a system with conformation dependent damping
Liouville's theorem, based on the Hamiltonian flow (micro-canonical ensemble) for a many particle system, indicates that the (stationary) equilibrium probability distribution is a function of the Hamiltonian. A canonical ensemble corresponds to a micro-canonical one at thermodynamic limit. On the contrary, the dynamics...
1209.3654v3
2012-09-17
Nonlinear emission of spin-wave caustics from an edge mode of a micro-structured Co2Mn0.6Fe0.4Si waveguide
Magnetic Heusler materials with very low Gilbert damping are expected to show novel magnonic transport phenomena. We report nonlinear generation of higher harmonics leading to the emission of caustic spin-wave beams in a low-damping, micro-structured Co2Mn0.6Fe0.4Si Heusler waveguide. The source for the higher harmonic...
1209.3669v2
2012-09-20
High Resolution BPM Upgrade for the ATF Damping Ring at KEK
A beam position monitor (BPM) upgrade at the KEK Accelerator Test Facility (ATF) damping ring has been accomplished, carried out by a KEK/FNAL/SLAC collaboration under the umbrella of the global ILC R&D effort. The upgrade consists of a high resolution, high reproducibility read-out system, based on analog and processi...
1209.4569v1
2012-09-23
Ion Landau Damping on Drift Tearing Modes
Kinetic treatments of drift-tearing modes that match an inner resonant layer solution to an external MHD region solution, characterised by $\Delta^{\prime}$, fail to properly match the ideal MHD boundary condition on the parallel electric field, $E_{\parallel}.$ In this paper we demonstrate how consideration of ion sou...
1209.5054v3
2012-09-26
Inverse Energy Cascade in Forced 2D Quantum Turbulence
We demonstrate an inverse energy cascade in a minimal model of forced 2D quantum vortex turbulence. We simulate the Gross-Pitaevskii equation for a moving superfluid subject to forcing by a stationary grid of obstacle potentials, and damping by a stationary thermal cloud. The forcing injects large amounts of vortex ene...
1209.5824v2
2012-09-27
Comparison of non-Markovianity criteria in a qubit system under random external fields
We give the map representing the evolution of a qubit under the action of non-dissipative random external fields. From this map we construct the corresponding master equation that in turn allows us to phenomenologically introduce population damping of the qubit system. We then compare, in this system, the time-regions ...
1209.6331v2
2012-10-01
Gravitational Coleman-Weinberg Potential and It's Finite Temperature Counterpart
Coleman-Weinberg (CW) phenomena for the case of gravitons minimally coupled to massless scalar field is studied. The one loop effect completely vanishes if there is no self interaction term present in the matter sector. The one loop effective potential is shown to develop an instability in the form of acquiring an imag...
1210.0497v4
2012-10-09
Analytic approximate seismology of propagating MHD waves in the solar corona
Observations show that propagating magnetohydrodynamic (MHD) waves are ubiquitous in the solar atmosphere. The technique of MHD seismology uses the wave observations combined with MHD wave theory to indirectly infer physical parameters of the solar atmospheric plasma and magnetic field. Here we present an analytical se...
1210.2689v1
2012-10-12
Reversal of magnetization of a single-domain magnetic particle by the ac field of time-dependent frequency
We report numerical and analytical studies of the reversal of the magnetic moment of a single-domain magnetic particle by a circularly polarized ac field of time-dependent frequency. For the time-linear frequency sweep, the phase diagrams are computed that illustrate the dependence of the reversal on the frequency swee...
1210.3530v1
2012-10-18
SDO/AIA Observations of Large-Amplitude Longitudinal Oscillations in a Solar Filament
We present the first \emph{Solar Dynamics Observatory}/Atmospheric Imaging Assembly observations of the large-amplitude longitudinal (LAL) oscillations in the south and north parts (SP and NP) of a solar filament on 2012 April 7. Both oscillations are triggered by flare activities close to the filament. The period vari...
1210.5110v1
2012-10-31
The Kerr medium as an {\sf SU(2)} system
The Kerr medium in the presence of damping and associated with SU(1,1) symmetry, is solved using the techniques of Thermo field Dynamics (TFD).These TFD techniques, well studied earlier (Chaturvedi and Srinivasan, 1991), help us to exactly solve the Kerr medium as a spin damped system associated with SU(2) symmetry. Us...
1210.8240v1
2012-11-02
Dynamic Spin Injection into Chemical Vapor Deposited Graphene
We demonstrate dynamic spin injection into chemical vapor deposition (CVD) grown graphene by spin pumping from permalloy (Py) layers. Ferromagnetic resonance measurements at room temperature reveal a strong enhancement of the Gilbert damping at the Py/graphene interface, exceeding that observed in even Py/platinum inte...
1211.0492v1
2012-12-06
A simple and effective Verlet-type algorithm for simulating Langevin dynamics
We present a revision to the well known Stormer-Verlet algorithm for simulating second order differential equations. The revision addresses the inclusion of linear friction with associated stochastic noise, and we analytically demonstrate that the new algorithm correctly reproduces diffusive behavior of a particle in a...
1212.1244v4
2012-12-10
Shear viscosity and the r-mode instability window in superfluid neutron stars
We analyze how recent computations of the shear viscosity $\eta$ in the core of superfluid neutron stars affect the r-mode instability window. We first analyze the contribution of superfluid phonons to the viscosity, both in their hydrodynamical and ballistic regime. We also consider the recent computation of $\eta$ ar...
1212.2075v2
2012-12-12
The operator sum-difference representation for quantum maps: application to the two-qubit amplitude damping channel
On account of the Abel-Galois no-go theorem for the algebraic solution to quintic and higher order polynomials, the eigenvalue problem and the associated characteristic equation for a general noise dynamics in dimension $d$ via the Choi-Jamiolkowski approach cannot be solved in general via radicals. We provide a way ar...
1212.2780v1
2012-12-13
Efficiency improvement of the frequency-domain BEM for rapid transient elastodynamic analysis
The frequency-domain fast boundary element method (BEM) combined with the exponential window technique leads to an efficient yet simple method for elastodynamic analysis. In this paper, the efficiency of this method is further enhanced by three strategies. Firstly, we propose to use exponential window with large dampin...
1212.3032v2
2012-12-16
Decay of the solution to the bipolar Euler-Poisson system with damping in $\mathbb{R}^3$
We construct the global solution to the Cauchy's problem of the bipolar Euler-Poisson equations with damping in $\mathbb{R}^3$ when $H^3$ norm of the initial data is small. If further, the $\dot{H}^{-s}$ norm ($0\leq s<3/2)$ or $\dot{B}_{2,\infty}^{-s}$ norm ($0<s\leq3/2$) of the initial data is bounded, we give the op...
1212.3754v2
2012-12-24
Effects of kappa distribution function on Landau damping in electrostatic Vlasov simulation
Effects of non-thermal high-energy electrons on Langmuir wave-particle interaction are investigated by an initial value approach. A Vlasov-Poisson simulation is employed which is based on the splitting scheme by Cheng and Knorr [Cheng, C.Z. and G. Knorr, 1976: J. Comput. Phys. 22, 330-351.]. The kappa distribution func...
1212.5872v1
2012-12-26
Anomalous dynamic back-action in interferometers
We analyze the dynamic optomechanical back-action in signal-recycled Michelson and Michelson-Sagnac interferometers that are operated off dark port. We show that in this case --- and in contrast to the well-studied canonical form of dynamic back-action on dark port --- optical damping in a Michelson-Sagnac interferomet...
1212.6242v2
2013-01-01
A scattering approach to some aspects of the Schwarzschild Black Hole
In this paper, we consider a massless field, with spin j, in interaction with a Schwarzschild black hole in four dimensions, focusing mainly our study on the s-wave scattering. First, using a Fourier analysis, we show that one can have a simple and natural description of the Physics near the event horizon without using...
1301.0108v1
2013-01-02
Memory models of adaptive behaviour
Adaptive response to a varying environment is a common feature of biological organisms. Reproducing such features in electronic systems and circuits is of great importance for a variety of applications. Here, we consider memory models inspired by an intriguing ability of slime molds to both memorize the period of tempe...
1301.0209v2
2013-01-03
Collective modes of a two-dimensional spin-1/2 Fermi gas in a harmonic trap
We derive analytical expressions for the frequency and damping of the lowest collective modes of a two-dimensional Fermi gas using kinetic theory. For strong coupling, we furthermore show that pairing correlations overcompensate the effects of Pauli blocking on the collision rate for a large range of temperatures, resu...
1301.0358v2
2013-01-09
Synthesis of new neutron-rich heavy nuclei: An experimentalist's view
I attempt to experimentally evaluate the prospects of synthesizing new neutron- rich superheavy nuclei. I consider three possible synthetic paths to neutron- rich superheavy nuclei: (a) the use of neutron-rich radioactive beams. (b) the use of damped collisions and (c) the use of multi-nucleon transfer reactions. I con...
1301.1759v1
2013-01-10
First-principles calculation of the Gilbert damping parameter via the linear response formalism with application to magnetic transition-metals and alloys
A method for the calculations of the Gilbert damping parameter $\alpha$ is presented, which based on the linear response formalism, has been implemented within the fully relativistic Korringa-Kohn-Rostoker band structure method in combination with the coherent potential approximation alloy theory. To account for therma...
1301.2114v1
2013-01-13
Entanglement dynamics of non-inertial observers in a correlated environment
Effect of decoherence and correlated noise on the entanglement of X-type state of the Dirac fields in the non-inertial frame is investigated. A two qubit X-state is considered to be shared between the partners where Alice is in inertial frame and Rob in an accelerated frame. The concurrence is used to quantify the enta...
1301.2759v1
2013-01-13
Decoherence and multipartite entanglement of non-inertial observers
Decoherence effect on multipartite entanglement in non-inertial frames is investigated. GHZ state is considered to be shared between the partners with one partner in inertial frame whereas the other two in accelerated frames. One-tangle and {\pi}-tangles are used to quantify the entanglement of the multipartite system ...
1301.2765v2
2013-01-18
Current induced torques and interfacial spin-orbit coupling: Semiclassical Modeling
In bilayer nanowires consisting of a ferromagnetic layer and a non-magnetic layer with strong spin-orbit coupling, currents create torques on the magnetization beyond those found in simple ferromagnetic nanowires. The resulting magnetic dynamics appear to require torques that can be separated into two terms, damping-li...
1301.4513v1
2013-01-25
Driven skyrmions and dynamical transitions in chiral magnets
We study the dynamics of skyrmions in chiral magnets in the presence of a spin polarized current. The motion of skyrmions in the ferromagnetic background excites spin waves and contributes to additional damping. At a large current, the spin wave spectrum becomes gapless and skyrmions are created dynamically from the fe...
1301.5963v2
2013-02-13
Entanglement of Tripartite States with Decoherence in Noninertial frames
The one-tangle and {\pi}-tangle are used to quantify the entanglement of a tripartite GHZ state in noninertial frames when the system interacts with a noisy environment in the form of phase damping, phase flip and bit flip channel. It is shown that the two-tangles behave as a closed system. The one-tangle and {\pi}-tan...
1302.3005v1
2013-02-17
Global existence and exponential growth for a viscoelastic wave equation with dynamic boundary conditions
The goal of this work is to study a model of the wave equation with dynamic boundary conditions and a viscoelastic term. First, applying the Faedo-Galerkin method combined with the fixed point theorem, we show the existence and uniqueness of a local in time solution. Second, we show that under some restrictions on the ...
1302.4036v1
2013-02-22
Mixing of blackbodies: Increasing our view of inflation to 17 e-folds with spectral distortions from Silk damping
Silk damping in the early Universe, before and during recombination, erases anisotropies in the cosmic microwave background (CMB) on small scales. This power, which disappears from anisotropies, appears in the monopole as y-type, i-type and \mu-type distortions. The observation of the CMB spectral distortions will thus...
1302.5633v1
2013-02-26
Tenfold reduction of Brownian noise in optical interferometry
Thermally induced fluctuations impose a fundamental limit on precision measurement. In optical interferometry, the current bounds of stability and sensitivity are dictated by the excess mechanical damping of the high-reflectivity coatings that comprise the cavity end mirrors. Over the preceding decade, the mechanical l...
1302.6489v1
2013-03-01
Quantum error correction and detection: quantitative analysis of a coherent-state amplitude damping code
We re-examine a non-Gaussian quantum error correction code designed to protect optical coherent-state qubits against errors due to an amplitude damping channel. We improve on a previous result [Phys. Rev. A 81, 062344 (2010)] by providing a tighter upper bound on the performance attained when considering realistic assu...
1303.0273v2
2013-03-04
Transverse oscillations in solar spicules induced by propagating Alfvenic pulses
The excitation of Alfvenic waves in the solar spicules due to the localized Alfvenic pulse is investigated. A set of incompressible MHD equations in two dimensional $x-z$ plane with steady flows and sheared magnetic fields is solved. Stratification due to gravity and transition region between chromosphere and corona ar...
1303.0833v1
2013-03-04
Tidal damping of the mutual inclination in hierachical systems
Hierarchical two-planet systems, in which the inner body's semi-major axis is between 0.1 and 0.5 AU, usually present high eccentricity values, at least for one of the orbits. As a result of the formation process, one may expect that planetary systems with high eccentricities also have high mutual inclinations. However...
1303.0864v2
2013-03-05
Anomalous velocity distributions in active Brownian suspensions
Large scale simulations and analytical theory have been combined to obtain the non-equilibrium velocity distribution, $f(v)$, of randomly accelerated particles in suspension. The simulations are based on an event-driven algorithm, generalised to include friction. They reveal strongly anomalous but largely universal dis...
1303.0996v3
2013-03-07
Quantum critical metals in $d=3+1$
We study the problem of disorder-free metals near a continuous Ising nematic quantum critical point in $d=3+1$ dimensions. We begin with perturbation theory in the `Yukawa' coupling between the electrons and undamped bosons (nematic order parameter fluctuations) and show that the perturbation expansion breaks down belo...
1303.1587v2
2013-03-08
Ultra High Energy Electrons Powered by Pulsar Rotation
A new mechanism of particle acceleration to ultra high energies, driven by the rotational slow down of a pulsar (Crab pulsar, for example), is explored. The rotation, through the time dependent centrifugal force, can very efficiently excite unstable Langmuir waves in the e-p plasma of the star magnetosphere via a param...
1303.2093v1
2013-04-01
Fidelity of remote state preparation can be enhanced by local operation
Remote state preparation (RSP) is a quantum information protocol which allows preparing a quantum state at a distant location with the help of a preshared nonclassical resource state and a classical channel. The efficiency of successfully doing this task can be represented by the RSP-fidelity of the resource state. In ...
1304.0283v1