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2009-12-24
A resonance model with magnetic connection for 3:2 HFQPO pairs in black hole binaries
We apply epicyclic resonances to the magnetic connection (MC) of a black hole (BH) with a relativistic accretion disc, interpreting the high frequency quasi-periodic oscillations (HFQPOs) with 3:2 pairs observed in three BH X-ray binaries. It turns out that the 3:2 HFQPO pairs are associated with the steep power-law st...
0912.4776v1
2010-01-03
Stabilities for Euler-Poisson Equations with Repulsive Forces in R^N
This article extends the previous paper in "M.W. Yuen, \textit{Stabilities for Euler-Poisson Equations in Some Special Dimensions}, J. Math. Anal. Appl. \textbf{344} (2008), no. 1, 145--156.", from the Euler-Poisson equations for attractive forces to the repulsive ones in $R^{N}$ $(N\geq2)$. The similar stabilities of ...
1001.0385v1
2010-01-10
Production of entanglement in Raman three-level systems using feedback
We examine the theoretical limits of the generation of entanglement in a damped coupled ion-cavity system using jump-based feedback. Using Raman transitions to produce entanglement between ground states reduces the necessary feedback bandwidth, but does not improve the overall effect of the spontaneous emission on the ...
1001.1567v1
2010-01-15
Coulomb screening and collective excitations in biased bilayer graphene
We have investigated the Coulomb screening properties and plasmon spectrum in a bilayer graphene under a perpendicular electric bias. The bias voltage applied between the two graphene layers opens a gap in the single particle energy spectrum and modifies the many-body correlations and collective excitations. The energy...
1001.2762v1
2010-01-18
Quiet sigma delta quantization, and global convergence for a class of asymmetric piecewise affine maps
In this paper, we introduce a family of second-order sigma delta quantization schemes for analog-to-digital conversion which are `quiet' : quantization output is guaranteed to fall to zero at the onset of vanishing input. In the process, we prove that the origin is a globally attractive fixed point for the related fami...
1001.2955v2
2010-01-20
Non-Markovian dynamics of a damped driven two-state system
We study a driven two-state system interacting with a structured environment. We introduce the non-Markovian master equation ruling the system dynamics, and we derive its analytic solution for general reservoir spectra. We compare the non-Markovian dynamics of the Bloch vector for two classes of reservoir spectra: the ...
1001.3564v2
2010-01-26
Non-Markovian reservoir-dependent squeezing
The squeezing dynamics of a damped harmonic oscillator are studied for different types of environment without making the Markovian approximation. The squeezing dynamics of a coherent state depend on the reservoir spectrum in a unique way that can, in the weak coupling approximation, be analyzed analytically. Comparison...
1001.4669v1
2010-02-01
Non linear diffusion and wave damped propagation : weak solutions and statistical turbulence behavior
We present mathematical proofs on the existence and uniqueness of weak solutions for a special class of non linear parabolic and hyperbolic equations of mathematical physics subject to colored noise (structured turbulence) as random- initial conditions
1002.0165v2
2010-02-04
Sudden violation of the CHSH inequality in a two qubits system
I study the dynamics of the violation of the CHSH inequality for two qubits interacting with a common zero-temperature non-Markovian environment. I demonstrate sudden violation of the inequality for two qubits initially prepared in a factorized state. Due to the strong coupling between the qubits and the reservoir, the...
1002.1000v1
2010-02-08
Backward Raman compression of x-rays in metals and warm dense matters
Experimentally observed decay rate of the long wavelength Langmuir wave in metals and dense plasmas is orders of magnitude larger than the prediction of the prevalent Landau damping theory. The discrepancy is explored, and the existence of a regime where the forward Raman scattering is stable and the backward Raman sca...
1002.1735v2
2010-02-09
The pulse and monochromatic light stimulation of semiconductor quantum wells
The light reflectance and absorbance are calculated for a quantum well (QW) the width of which is comparable with the light wave length. The difference of the refraction coefficients of the quantum well and barriers is taken into account. The stimulating pulse form is arbitrary. An existence of two closely situated dis...
1002.1780v1
2010-02-09
Asymptotical photon distributions in the dissipative Dynamical Casimir Effect
Asymptotical formulas for the photon distribution function of a quantum oscillator with time-dependent frequency and damping coefficients, interacting with a thermal reservoir, are derived in the case of a large mean number of quanta. Different regimes of excitation of an initial thermal state with an arbitrary tempera...
1002.1861v1
2010-02-16
Dynamical Unbinding Transition in a Periodically Driven Mott Insulator
We study the double occupancy in a fermionic Mott insulator at half-filling generated via a dynamical periodic modulation of the hopping amplitude. Tuning the modulation amplitude, we describe a crossover in the nature of doublon-holon excitations from a Fermi Golden Rule regime to damped Rabi oscillations. The decay t...
1002.3085v1
2010-02-19
Observation of magnetocoriolis waves in a liquid metal Taylor-Couette experiment
The first observation of fast and slow magnetocoriolis (MC) waves in a laboratory experiment is reported. Rotating nonaxisymmetric modes arising from a magnetized turbulent Taylor-Couette flow of liquid metal are identified as the fast and slow MC waves by the dependence of the rotation frequency on the applied field s...
1002.3791v1
2010-03-11
Exact quasinormal modes for a special class of black holes
Analytic exact expressions for the quasinormal modes of scalar and electromagnetic perturbations around a special class of black holes are found in d\ge3 dimensions. It is shown that, the size of the black hole provides a bound for the angular momentum of the perturbation. Quasinormal modes appear when this bound is fu...
1003.2256v1
2010-03-12
Symmetry Analysis of 2+1 dimensional Burgers equation with variable damping
The symmetry classification of the two dimensional Burgers equation with variable coefficient is considered. Symmetry algebra is found and a classification of its subalgebras, up to conjugacy, is obtained. Similarity reductions are performed for each class.
1003.2511v1
2010-03-16
Driven Dirac-like Equation via Mirror Oscillation: Controlled Cold-Atom Zitterbewegung
By considering mirror oscillation in a "tripod-scheme" laser-atom system, we advocate explorative studies of driven Dirac-like equations. Both analytical and numerical studies show that mirror oscillation can be used to drive an effective spin-orbit interaction and hence control the amplitude, the frequency, and the da...
1003.3074v1
2010-03-18
Stimulated Raman adiabatic passage in an open quantum system: Master equation approach
A master equation approach to the study of environmental effects in the adiabatic population transfer in three-state systems is presented. A systematic comparison with the non-Hermitian Hamiltonian approach [N. V. Vitanov and S. Stenholm, Phys. Rev. A {\bf 56}, 1463 (1997)] shows that in the weak coupling limit the two...
1003.3616v1
2010-03-19
Self-stimulated Emission of Undulator Radiation
We attract attention that interaction of particle in downstream undulator with its own wavelet emitted in upstream undulator could be as strong as with the frictional field in undulator itself. This phenomenon could be used for enhancement of signal from pickup undulators in optical stochastic cooling methods as well a...
1003.3747v1
2010-03-19
Dynamics of magnetization on the topological surface
We investigate theoretically the dynamics of magnetization coupled to the surface Dirac fermions of a three dimensional topological insulator, by deriving the Landau-Lifshitz-Gilbert (LLG) equation in the presence of charge current. Both the inverse spin-Galvanic effect and the Gilbert damping coefficient $\alpha$ are ...
1003.3769v1
2010-03-23
Effect of extra dimensions on gravitational waves from cosmic strings
We show how taking into account the kinematical effect of extra dimensions can have a significant impact on the gravity wave emission from cosmic strings. Additional dimensions both round off cusps, as well as reduce the probability of their formation. We recompute the cusp gravity wave burst with these factors and fin...
1003.4395v2
2010-03-31
Energy carriers in the Fermi-Pasta-Ulam $β$ lattice: Solitons or Phonons?
We investigate anomalous energy transport processes in the Fermi-Pasta-Ulam $\beta$ lattice. They are determined by the maximum sound velocity of the relevant weakly damped energy carriers. That velocity can be numerically resolved by measuring the propagating fronts of the correlation functions of energy/momentum fluc...
1003.6113v1
2010-04-07
Neutrino Flavor Ratio on Earth and at Astrophysical Sources
We present the reconstruction of neutrino flavor ratios at astrophysical sources. For distinguishing the pion source and the muon-damped source to the 3$\sigma$ level, the neutrino flux ratios, $R\equiv\phi(\nu_\mu)/(\phi(\nu_e)+\phi(\nu_\tau))$ and $S\equiv\phi(\nu_e)/\phi(\nu_\tau)$, need to be measured in accuracies...
1004.1030v1
2010-04-08
Ab initio vibrations in nonequilibrium nanowires
We review recent results on electronic and thermal transport in two different quasi one-dimensional systems: Silicon nanowires (SiNW) and atomic gold chains. For SiNW's we compute the ballistic electronic and thermal transport properties on equal footing, allowing us to make quantitative predictions for the thermoelect...
1004.1312v1
2010-04-08
Spin-charge and spin-orbital coupling effects on spin dynamics in ferromagnetic manganites
Correlation-induced spin-charge and spin-orbital coupling effects on spin dynamics in ferromagnetic manganites are calculated with realistic parameters in order to provide a quantitative comparison with experimental results for spin stiffness, magnon dispersion, magnon damping, anomalous zone-boundary magnon softening,...
1004.1352v2
2010-04-12
Existence and stability of steady states of a reaction convection diffusion equation modeling microtubule formation
We generalize the Dogterom-Leibler model for microtubule dynamics [DL] to the case where the rates of elongation as well as the lifetimes of the elongating and shortening phases are a function of GTP-tubulin concentration. We study also the effect of nucleation rate in the form of a damping term which leads to new stea...
1004.1866v1
2010-04-14
Non-equilibrium Effects in the Thermal Switching of Underdamped Josephson Junctions
We study the thermal escape problem in the low damping limit. We find that finiteness of the barrier is crucial for explaining the thermal activation results. In this regime low barrier non-equilibrium corrections to the usual theories become necessary. We propose a simple theoretical extension accounting for these non...
1004.2512v1
2010-04-18
Fundamental defect of the macroeconomic thinking as one of the main causes of the crisis endured
The main points of the first section of the article written by S.I. Chernyshov, A.V. Voronin and S.A. Razumovsky arXiv:1003.4382), which deals with the fundamental bases of the macroeconomic theory, have been analyzed. An incorrectness of the Harrod's model of the economical growth in its generally accepted interpretat...
1004.3067v1
2010-04-19
Occurrence of superconductivity when the metal-insulator transition is inhibited in $1T$-TaS${_2}$
When a Mott metal-insulator transition is inhibited by a small amount of disorder in the layered dichalcogenide 1T-TaS$_2$, an inhomogeneous superconducting state arises below T=2.1 K, and coexists with a nearly-commensurate charge-density-wave. By angle-resolved photoelectron spectroscopy (ARPES) we show that it emerg...
1004.3251v1
2010-05-06
A probability-conserving dissipative Schrödinger equation
Dissipative effects on a microscopic level are included in the Schr\"odinger equation. When the decay between different local levels as a result of the coupling to a bath, the Schr\"odinger equation no longer conserves energy, but the probability of the states is conserved. The procedure is illustrated with several exa...
1005.1079v1
2010-05-10
A New Approach to Non-Commutative U(N) Gauge Fields
Based on the recently introduced model of arXiv:0912.2634 for non-commutative U(1) gauge fields, a generalized version of that action for U(N) gauge fields is put forward. In this approach to non-commutative gauge field theories, UV/IR mixing effects are circumvented by introducing additional 'soft breaking' terms in t...
1005.1578v2
2010-05-18
The effect of extra dimensions on gravity wave bursts from cosmic string cusps
We explore the kinematical effect of having extra dimensions on the gravity wave emission from cosmic strings. Additional dimensions both round off cusps, and reduce the probability of their formation. We recompute the gravity wave burst, taking into account these two factors, and find a potentially significant damping...
1005.3220v2
2010-05-24
Direct observation of paramagnons in palladium
We report an inelastic neutron scattering study of the spin fluctuations in the nearly-ferromagnetic element palladium. Dispersive over-damped collective magnetic excitations or ``paramagnons'' are observed up to 128 meV. We analyze our results in terms of a Moriya-Lonzarich-type spin fluctuation model and estimate the...
1005.4402v1
2010-06-01
High Gradient Superconducting Cavity with Low Surface EM Fields and Well-Suppressed HOMS for the ILC
We present an optimized geometry for a 1.3 GHz superconducting cavity in which the surface electromagnetic fields have been minimized and the bandwidth of the fundamental mode has been maximized. We refer to this design as the New Low Surface Field (NLSF) cavity. Earlier work focused on properties of the fundamental mo...
1006.0086v1
2010-06-14
Transport parameters in neutron stars from in-medium NN cross sections
We present a numerical study of shear viscosity and thermal conductivity of symmetric nuclear matter, pure neutron matter and $\beta$-stable nuclear matter, in the framework of the Brueckner theory. The calculation of in-medium cross sections and nucleon effective masses is performed with a consistent two and three bod...
1006.2656v1
2010-06-25
Perturbations of Mathieu equations with parametric excitation of large period
We consider a linear differential system of Mathieu equations with periodic coefficients over periodic closed orbits and we prove that, arbitrarily close to this system, there is a linear differential system of Hamiltonian damped Mathieu equations with periodic coefficients over periodic closed orbits such that, all bu...
1006.5025v1
2010-07-01
Instability of ion kinetic waves in a weakly ionized plasma
The fundamental higher-order Landau plasma modes are known to be generally heavily damped. We show that these modes for the ion component in a weakly ionized plasma can be substantially modified by ion-neutral collisions and a dc electric field driving ion flow so that some of them can become unstable. This instability...
1007.0142v3
2010-07-06
Temperature and Friction Accelerated Sampling of Boltzmann-Gibbs Distribution
This paper is concerned with tuning friction and temperature in Langevin dynamics for fast sampling from the canonical ensemble. We show that near-optimal acceleration is achieved by choosing friction so that the local quadratic approximation of the Hamiltonian is a critical damped oscillator. The system is also over-h...
1007.0995v1
2010-07-09
Purely electrical damping of vibrations in arbitrary PEM plates: a mixed non-conforming FEM-Runge-Kutta time evolution analysis
A new numerical code, based upon a mixed FEM-Runge-Kutta method, is used for the analysis and design of plane 2-D smart structures. The code is applied to the study of arbitrarily shaped PEM plates, based on a weak formulation of their governing equations, [17]. The optimal parameters needed to synthesize appropriate e...
1007.1581v1
2010-08-02
Entanglement and teleportation via chaotic system
The dynamics of entangled state interacting with a single cavity mode is investigated in the presence of a random parameter. We have shown that degree of entanglement decays with time and rate of decay is defined by features of random parameter. Quantum teleportation through dissipative channal and teleportation fideli...
1008.0323v1
2010-08-03
AMENDART in Markovian circuit QED
We study the cavity field's and atomic asymptotic mean excitation numbers due to anti-rotating term (AMENDART) in the circuit Quantum Electrodynamics (circuit QED) system, composed of a two-level atom and a single cavity field mode, subject to Markovian damping and dephasing mechanisms. We show that the AMENDART are ab...
1008.0564v2
2010-08-04
Quantum open systems approach to the dynamical Casimir effect
We analyze the introduction of dissipative effects in the study of the dynamical Casimir effect. We consider a toy model for an electromagnetic cavity that contains a semiconducting thin shell, which is irradiated with short laser pulses in order to produce periodic oscillations of its conductivity. The coupling betwee...
1008.0786v1
2010-08-16
The probability distribution of a trapped Brownian particle in plane shear flows
We investigate the statistical properties of an over-damped Brownian particle that is trapped by a harmonic potential and simultaneously exposed to a linear shear flow or to a plane Poiseuille flow. Its probability distribution is determined via the corresponding Smoluchowski equation, which is solved analytically for ...
1008.2670v3
2010-09-04
Combined Influence of Off-diagonal System Tensors and Potential Valley Returning of the Optimal Path
The two-dimensional barrier passage is studied in the framework of Langevin statistical reactive dynamics. The optimal incident angle for a particle diffusing in the dissipative non-orthogonal environment with various strengths of coupling between the two degrees of freedom is systematically calculated. The optimal dif...
1009.0835v1
2010-09-11
Critical density of urban traffic
A modified version of the Intelligent Driver Model was used to simulate traffic in the district of Afogados, in the city of Recife, Brazil, with the objective to verify whether the complexity of the underlying street grid, with multiple lane streets, crossings, and semaphores, is capable of exhibiting the effect of cri...
1009.2180v1
2010-09-11
Nonlinear optical response of hole-trion systems in quantum dots in tilted magnetic fields
We discuss, from a theoretical point of view, the four wave mixing spectroscopy on an ensemble of p-doped quantum dots in a magnetic field slightly tilted from the in-plane configuration. We describe the system evolution in the density matrix formalism. In the limit of coherent ultrafast optical driving, we obtain anal...
1009.2202v1
2010-09-17
Linear response calculation using the canonical-basis TDHFB with a schematic pairing functional
A canonical-basis formulation of the time-dependent Hartree-Fock-Bogoliubov (TDHFB) theory is obtained with an approximation that the pair potential is assumed to be diagonal in the time-dependent canonical basis. The canonical-basis formulation significantly reduces the computational cost. We apply the method to linea...
1009.3339v1
2010-10-14
Behavior of test particles in the plasma sheath upon local bias and plasma switching
Equilibrating gravitation by electric forces, microparticles can be confined in the plasma sheath above suitably biased local electrodes.Their position depends on the detailed structure of the plasma sheath and on the charge that the particles acquire in the surrounding plasma, that is by the electron and ion currents ...
1010.2862v1
2010-10-15
Anomalous diffusion in viscosity landscapes
Anomalous diffusion is predicted for Brownian particles in inhomogeneous viscosity landscapes by means of scaling arguments, which are substantiated through numerical simulations. Analytical solutions of the related Fokker-Planck equation in limiting cases confirm our results. For an ensemble of particles starting at a...
1010.3115v1
2010-10-17
Coherent soft-mode phonon generation and detection in ultrathin SrTiO3 grown directly on silicon
Time-resolved two color pump-probe polarization spectroscopy was performed at room temperature on SrTiO3 films grown directly on Si with film thickness varying from 2 nm to 7.8 nm. The E soft mode with a characteristic frequency of 0.2 THz is impulsively generated and measured in these coherently strained tetragonal ph...
1010.3443v1
2010-11-09
Hamiltonian formulation of the effective kinetic theory for superfluid Fermi liquids
We present in a local form the time dependent effective description of a superfluid Fermi liquid which includes Landau damping effects at $T\neq 0$. This is achieved by the introduction of an additional variable, the quasiparticle distribution function, which obeys a simple kinetic equation. The transport equation is c...
1011.2040v1
2010-11-15
Decoherence Strength of Multiple Non-Markovian Environments
It is known that one can characterize the decoherence strength of a Markovian environment by the product of its temperature and induced damping, and order the decoherence strength of multiple environments by this quantity. We show that for non-Markovian environments in the weak coupling regime there also exists a natur...
1011.3286v3
2010-11-18
Stochastic Resonance in Periodic Potentials
The phenomenon of stochastic resonance (SR) is known to occur mostly in bistable systems. However, the question of occurrence of SR in periodic potential systems is not conclusively resolved. Our present numerical work shows that the periodic potential system indeed exhibits SR in the high frequency regime, where the l...
1011.4198v2
2010-11-19
Spin waves in magnetic quantum wells with Coulomb interaction and $sd$ exchange coupling
We theoretically describe the spin excitation spectrum of a two dimensional electron gas embedded in a quantum well with localized magnetic impurities. Compared to the previous work, we introduce equations that allow to consider the interplay between the Coulomb interaction of delocalized electrons and the $sd$ exchang...
1011.4422v1
2010-11-22
Global p-mode oscillations throughout the complete solar cycle 23 and the beginning of cycle 24
The parameters of the p-mode oscillations vary with solar activity. Such temporal variations provide insights for the study of the structural and dynamical changes occurring in the Sun's interior throughout the solar cycle. We present here a complete picture of the temporal variations of the global p-mode parameters (e...
1011.4966v1
2010-11-24
Evolution equation of entanglement for multi-qubit systems
We discuss entanglement evolution of a multi-qubit system when one of its qubits is subjected to a general noisy channel. For such a system, an evolution equation of entanglement for a lower bound for multi-qubit concurrence is derived. Using this evolution equation, the entanglement dynamics of an initially mixed thre...
1011.5348v1
2010-12-06
Two Proposals for Robust PCA using Semidefinite Programming
The performance of principal component analysis (PCA) suffers badly in the presence of outliers. This paper proposes two novel approaches for robust PCA based on semidefinite programming. The first method, maximum mean absolute deviation rounding (MDR), seeks directions of large spread in the data while damping the eff...
1012.1086v3
2010-12-07
Cavity cooling of a mechanical resonator in the presence of two-level-system defects
Cavity cooling via quantum backaction force can extract thermal fluctuations from a mechanical resonator to reach the quantum ground state. Surface or bulk two-level-system (TLS) defects in a mechanical resonator can couple with the mechanical mode via deformation potential and affect the cooling process significantly....
1012.1380v2
2010-12-10
Spin-orbit driven ferromagnetic resonance: A nanoscale magnetic characterisation technique
We demonstrate a scalable new ferromagnetic resonance (FMR) technique based on the spin-orbit interaction. An alternating current drives FMR in uniform ferromagnetic structures patterned from the dilute magnetic semiconductors (Ga,Mn)As and (Ga,Mn)(As,P). This allows the direct measurement of magnetic anisotropy coeffi...
1012.2397v1
2010-12-12
Quasi-two-dimensional optomechanical crystals with a complete phononic bandgap
A fully planar two-dimensional optomechanical crystal formed in a silicon microchip is used to create a structure devoid of phonons in the GHz frequency range. A nanoscale photonic crystal cavity is placed inside the phononic bandgap crystal in order to probe the properties of the localized acoustic modes. By studying ...
1012.2556v1
2010-12-22
Discovering author impact: A PageRank perspective
This article provides an alternative perspective for measuring author impact by applying PageRank algorithm to a coauthorship network. A weighted PageRank algorithm considering citation and coauthorship network topology is proposed. We test this algorithm under different damping factors by evaluating author impact in t...
1012.4870v1
2010-12-29
On sub-ideal causal smoothing filters
Smoothing causal linear time-invariant filters are studied for continuous time processes. The paper suggests a family of causal filters with almost exponential damping of the energy on the higher frequencies. These filters are sub-ideal meaning that a faster decay of the frequency response would lead to the loss of cau...
1012.5883v3
2011-01-06
Dissipative dynamics of a harmonically confined Bose-Einstein condensate
We study the dissipation of the centre of mass oscillation of a harmonically confined condensate in the presence of a disorder potential. An extension of the Generalized Harmonic Theorem allows one to formulate the dynamics from the point of view of an oscillating disorder potential. This formulation leads to a rigorou...
1101.1332v2
2011-01-25
Magnetic field generated by r-modes in accreting quark stars
We show that the r-mode instability can generate strong toroidal fields in the core of accreting millisecond quark stars by inducing differential rotation. We follow the spin frequency evolution on a long time scale taking into account the magnetic damping rate in the evolution equations of r-modes. The maximum spin fr...
1101.4875v1
2011-02-04
Long-Term Damped Dynamics of the Extensible Suspension Bridge
This work is focused on the doubly nonlinear equation, whose solutions represent the bending motion of an extensible, elastic bridge suspended by continuously distributed cables which are flexible and elastic with stiffness k^2. When the ends are pinned, long-term dynamics is scrutinized for arbitrary values of axial l...
1102.0877v1
2011-02-07
Experimental demonstration of decoherence suppression via quantum measurement reversal
Taming decoherence is essential in realizing quantum computation and quantum communication. Here we experimentally demonstrate that decoherence due to amplitude damping can be suppressed by exploiting quantum measurement reversal in which a weak measurement and the reversing measurement are introduced before and after ...
1102.1303v2
2011-02-11
Simple proof of the robustness of Gaussian entanglement in bosonic noisy channels
The extremality of Gaussian states is exploited to show that Gaussian states are the most robust, among all possible bipartite continuous-variable states at fixed energy, against disentanglement due to noisy evolutions in Markovian Gaussian channels involving dissipation and thermal hopping. This proves a conjecture ra...
1102.2356v1
2011-02-25
First-principles calculations of magnetization relaxation in pure Fe, Co, and Ni with frozen thermal lattice disorder
The effect of the electron-phonon interaction on magnetization relaxation is studied within the framework of first-principles scattering theory for Fe, Co, and Ni by displacing atoms in the scattering region randomly with a thermal distribution. This "frozen thermal lattice disorder" approach reproduces the non-monoton...
1102.5305v2
2011-02-26
Dynamics of Skyrmion Crystals in Metallic Thin Films
We study the collective dynamics of the Skyrmion crystal (SkX) in thin films of ferromagnetic metals resulting from the nontrivial Skyrmion topology. We show that the current-driven motion of the crystal reduces the topological Hall effect and the Skyrmion trajectories bend away from the direction of the electric curre...
1102.5384v2
2011-03-06
Rapid cooling of neutron star in Cassiopeia A and r-mode damping in the core
We proposed alternative explanation to the rapid cooling of neutron star in Cas A. It is suggested that the star is experiencing the recovery period following the r-mode heating process,assuming the star is differentially rotating. Like the neutron-superfluidity-triggering model, our model predicts the rapid cooling wi...
1103.1092v3
2011-03-11
Dynamic Systems Model for Ionic Mem-Resistors based on Harmonic Oscillation
Memristive system models have previously been proposed to describe ionic memory resistors. However, these models neglect the mass of ions and repulsive forces between ions and are not well formulated in terms of semiconductor and ionic physics. This article proposes an alternative dynamic systems model in which the sys...
1103.2190v4
2011-03-14
Conflicting coupling of the unpaired nucleons and the structure of collective bands in odd-odd nuclei
Conflicting coupling of unpaired nucleons in the odd-odd nuclei is discussed. A very simple explanation is suggested for the damping of the energy spacing of the lowest levels in the rotational bands in the odd-odd nuclei in the case of a "conflicting" coupling of the odd proton and neutron comparative to those of the ...
1103.2609v1
2011-03-20
Rational Design of Half-Metallic Heterostructures
We present a rational approach to the design of half-metallic heterostructures which allows the design of an infinite number of half-metallic heterostructures. The wide range of materials that can be made half-metallic using our approach makes it possible to engineer materials with tunable characteristic properties, fo...
1103.3855v1
2011-03-20
Uniform resolvent estimates for a non-dissipative Helmholtz equation
We study the high frequency limit for a non-dissipative Helmholtz equation. We first prove the absence of eigenvalue on the upper half-plane and close to an energy which satisfies a weak damping assumption on trapped trajectories. Then we generalize to this setting the resolvent estimates of Robert-Tamura and prove the...
1103.3868v1
2011-03-24
Effect of nonadiabatic spin transfer torque on domain wall resonance frequency and mass
The dynamics of a magnetic domain wall in a semi circular nanowire loop is studied by an analytical model and micromagnetic simulations. We find a damped sinusoidal oscillation of the domain wall for small displacement angles around its equilibrium position under an external magnetic field in the absence of currents. B...
1103.4670v1
2011-03-25
Multipartite entanglement for open system in noninertial frames
Based on Greenberger-Horne-Zeilinger ($GHZ$) and $W$ initial states, the tripartite entanglement of a fermionic system under the amplitude damping channel and in depolarizing noise when two subsystems accelerated is investigated. Unlike the case of two-qubit system in which sudden death occurs easily, we find here that...
1103.4903v1
2011-04-08
Coherence and Instability in a Driven Bose-Einstein Condensate: A Fully Dynamical Number-Conserving Approach
We consider a Bose-Einstein condensate driven by periodic delta-kicks. In contrast to first-order descriptions, which predict rapid, unbounded growth of the noncondensate in resonant parameter regimes, the consistent treatment of condensate depletion in our fully-time-dependent, second-order description acts to damp th...
1104.1521v3
2011-04-25
Rotation of Comet Hartley 2 from Structures in the Coma
The CN coma structure of the EPOXI mission target, comet 103P/Hartley 2, was observed during twenty nights from September to December 2010. These CN images probe the rotational state of the comet's nucleus and provide a ground-based observational context to complement the EPOXI observations. A dynamically excited comet...
1104.4672v1
2011-05-11
Dispersion and damping of multi-quantum well polaritons from resonant Brillouin scattering by folded acoustic modes
We report on confined exciton resonances of acoustic and folded acoustic phonon light scattering in a GaAs/AlAs multi-quantum-well. Significant variations of the line shifts and widths are observed across the resonance and quantitatively reproduced in terms of the polariton dispersion. This high resolution Brillouin st...
1105.2229v1
2011-05-23
Radiative damping: a case study
We are interested in the motion of a classical charge coupled to the Maxwell self-field and subject to a uniform external magnetic field, B. This is a physically relevant, but difficult dynamical problem, to which contributions range over more than one hundred years. Specifically, we will study the Sommerfeld-Page appr...
1105.4470v1
2011-05-27
Creating quantum correlations through local non-unitary memoryless channels
We show that two qubits, initially in a fully classical state, can develop significant quantum correlations as measured by the quantum discord (QD) under the action of a local memoryless noise (specifically we consider the case of a Markovian amplitude-damping channel). This is analytically proven after deriving in a c...
1105.5551v3
2011-06-01
Indirect stabilization of weakly coupled systems with hybrid boundary conditions
We investigate stability properties of indirectly damped systems of evolution equations in Hilbert spaces, under new compatibility assumptions. We prove polynomial decay for the energy of solutions and optimize our results by interpolation techniques, obtaining a full range of power-like decay rates. In particular, we ...
1106.0263v2
2011-06-02
Density response of a trapped Fermi gas: a crossover from the pair vibration mode to the Goldstone mode
We consider the density response of a trapped two-component Fermi gas. Combining the Bogoliubov-deGennes method with the random phase approximation allows the study of both collective and single particle excitations. Calculating the density response across a wide range of interactions, we observe a crossover from a wea...
1106.0430v2
2011-06-07
Electromagnetically induced transparency with Rydberg atoms
We present a theory of electromagnetically induced transparency in a cold ensemble of strongly interacting Rydberg atoms. Long-range interactions between the atoms constrain the medium to behave as a collection of superatoms, each comprising a blockade volume that can accommodate at most one Rydberg excitation. The pro...
1106.1360v2
2011-06-10
Discrete-time quadrature feedback cooling of a radio-frequency mechanical resonator
We have employed a feedback cooling scheme, which combines high-frequency mixing with digital signal processing. The frequency and damping rate of a 2 MHz micromechanical resonator embedded in a dc SQUID are adjusted with the feedback, and active cooling to a temperature of 14.3 mK is demonstrated. This technique can b...
1106.2106v1
2011-06-22
Magnetic excitations in iron pnictides
Spin wave dispersion and damping are investigated in the metallic SDW state of different itinerant electron models including a small interlayer hopping. Magnetic excitations in iron pnictides are shown to be well understood in terms of physical mechanisms characteristic of metallic magnets, such as carrier-induced ferr...
1106.4421v1
2011-06-22
Storing light as a mechanical excitation in a silica optomechanical resonator
We report the experimental demonstration of optomechanical light storage in a silica resonator. We use writing and readout laser pulses tuned to one mechanical frequency below an optical cavity resonance to control the coupling between the mechanical displacement and the optical field at the cavity resonance. The writi...
1106.4512v1
2011-07-18
Quantum gravity stability of isotropy in homogeneous cosmology
It has been shown that anisotropy of homogeneous spacetime described by the general Kasner metric can be damped by quantum fluctuations coming from perturbative quantum gravity in one-loop approximation. Also, a formal argument, not limited to one-loop approximation, is put forward in favor of stability of isotropy in ...
1107.3468v4
2011-07-19
Calculating a maximizer for quantum mutual information
We obtain a maximizer for the quantum mutual information for classical information sent over the quantum qubit amplitude damping channel. This is achieved by limiting the ensemble of input states to antipodal states, in the calculation of the product-state capacity for the channel, the resulting maximizing ensemble con...
1107.3741v1
2011-07-19
Damping of Bloch oscillations in the Hubbard model
Using nonequilibrium dynamical mean-field theory, we study the isolated Hubbard model in a static electric field in the limit of weak interactions. Linear response behavior is established at long times, but only if the interaction exceeds a critical value, below which the system exhibits an AC-type response with Bloch ...
1107.3830v1
2011-07-20
Fractional Equations of Kicked Systems and Discrete Maps
Starting from kicked equations of motion with derivatives of non-integer orders, we obtain "fractional" discrete maps. These maps are generalizations of well-known universal, standard, dissipative, kicked damped rotator maps. The main property of the suggested fractional maps is a long-term memory. The memory effects i...
1107.3953v1
2011-07-21
Averaging approximation to singularly perturbed nonlinear stochastic wave equations
An averaging method is applied to derive effective approximation to the following singularly perturbed nonlinear stochastic damped wave equation \nu u_{tt}+u_t=\D u+f(u)+\nu^\alpha\dot{W} on an open bounded domain $D\subset\R^n$\,, $1\leq n\leq 3$\,. Here $\nu>0$ is a small parameter characterising the singular perturb...
1107.4184v1
2011-08-03
Parametric amplification of magnetoplasmons in semiconductor quantum dots
We show that the magnetoplasmon collective modes in quasi-two-dimensional semiconductor quantum dots can be parametrically amplified by periodically modulating the magnetic field perpendicular to the nanostructure. The two magnetoplasmon modes are excited and amplified simultaneously, leading to an exponential growth o...
1108.0891v3
2011-08-09
Beam-beam studies for the High-Energy LHC
LHC upgrades are being considered both towards higher luminosity (HL-LHC) and towards higher energy (HE-LHC). In this paper we report initial studies of the beam-beam effects in the HE-LHC [1]. The HE-LHC aims at beam energies of 16.5 TeV, where the transverse emittance decreases due to synchrotron radiation with a 2-h...
1108.1871v1
2011-08-10
Protecting entangled states of two ions by engineering reservoir
We present a proposal for realizing local decoherence-free evolution of given entangled states of two two-level (TL) ions. For two TL ions coupled to a single heavily damped cavity, we can use engineering reservoir scheme to obtain a decoherence-free subspace which can be nonadiabatically controlled by the system and r...
1108.2186v1
2011-08-11
Weak Primordial Magnetic Fields and Anisotropies in the Cosmic Microwave Background Radiation
It is shown that small-scale magnetic fields present before recombination induce baryonic density inhomogeneities of appreciable magnitude. The presence of such inhomogeneities changes the ionization history of the Universe, which in turn decreases the angular scale of the Doppler peaks and increases Silk damping by ph...
1108.2517v1
2011-08-13
Demonstration of K-Kbar, B-Bbar, and D-Dbar Transitions with a Pair of Coupled Pendula
A setup of two coupled and damped pendula is used to demonstrate the main features of transitions beween neutral K, D, B mesons and their respective antiparticles, including CP violation in K Kbar transitions. The transitions are described by two-state Schr\"odinger equations. Since the real parts of their solutions ob...
1108.2772v2
2011-08-15
Structural transitions in hypersphere fluids: predictions of Kirkwood's approximation
We use an analytic criterion for vanishing of exponential damping of correlations developed previously (Piasecki et al, J. Chem. Phys., 133, 164507, 2010) to determine the threshold volume fractions for structural transitions in hard sphere systems in dimensions D=3,4,5 and 6, proceeding from the YBG hierarchy and usin...
1108.2919v1
2011-08-15
Directed transport in equilibrium : analysis of the dimer model with inertial terms
We have previously shown an analysis of our dimer model in the over-damped regime to show directed transport in equilibrium. Here we analyze the full model with inertial terms present to establish the same result. First we derive the Fokker-Planck equation for the system following a Galilean transformation to show that...
1108.2927v1
2011-09-01
Double adiabatic theory of collisionless geodesic acoustic modes in tokamaks
Collisionless geodesic acoustic modes in tokamaks being supersonic for large "safety factor" q, the CGL (G. Chew, M. Goldberger, F. Low, 1956)1 double-adiabatic fluid closure is applied to formulate a theory for these modes. The basic linear normal mode is obtained. External means to drive these modes at resonance, as ...
1109.0057v1