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2014-12-02
|
Hydrogen transport within graphene multilayers by means of flexural phonons
|
Graphene sustains transverse out-of-plane mechanical vibrations (flexural
phonons). At the nanometer scale, these appear as travelling ripples, or
cavities, if excited in counter-phase in alternate multilayers. In this work we
explore by means of classical molecular dynamics simulations the possibility of
using these moving nano-cavities to actively transport hydrogen. We find that
the gas can be efficiently transported for hundreds of nanometers in the wave
propagation direction, before the phonons damp down. Therefore, this effect
could be used to move and pump gases through multilayers graphene based
frameworks.
|
1412.0923v1
|
2014-12-05
|
Holographic Charge Oscillations
|
The Reissner-Nordstrom black hole provides the prototypical description of a
holographic system at finite density. We study the response of this system to
the presence of a local, charged impurity. Below a critical temperature, the
induced charge density, which screens the impurity, exhibits oscillations.
These oscillations can be traced to the singularities in the density-density
correlation function moving in the complex momentum plane. At finite
temperature, the oscillations are very similar to the Friedel oscillations seen
in Fermi liquids. However, at zero temperature the oscillations in the black
hole background remain exponentially damped, while Friedel oscillations relax
to a power-law
|
1412.2003v1
|
2014-12-12
|
Theory of rheology in confinement
|
The viscosity of fluids is generally understood in terms of kinetic
mechanisms, i.e., particle collisions, or thermodynamic ones as imposed through
structural distortions upon e.g. applying shear. Often the former is less
relevant, and (damped) Brownian particles are considered good fluid model
systems. We formulate a general theoretical approach for rheology in
confinement, based on the many particle diffusion equation, evaluated via
classical density functional theory. We discuss the viscosity for the situation
of two parallel walls in relative motion as a function of wall-to-wall
distance.
|
1412.4048v2
|
2014-12-11
|
Magnetic field induced spin-wave energy focusing
|
Spin waves can transport both energy and angular momentum over long distances
as they propagate. However, due to damping, their amplitude decreases
exponentially as they move away from the source, leaving little capability for
manipulating how much energy and angular momentum is to be delivered where.
Here we show that a suitable local reduction of the effective field can lead to
a large accumulation of spin wave energy far from the source. Moreover, both
the location and the amount of energy to be delivered can be controlled
accurately with geometry and externalm magnetic fields. Thus, we put forward a
general, robust and flexible approach to convey both heat and spin in
ferromagnets, which can be directly used in spintronic devices.
|
1412.4129v1
|
2014-12-17
|
Two-impurity helical Majorana problem
|
We predict experimentally accessible signatures for helical Majorana fermions
in a topological superconductor by coupling to two quantum dots in the local
moment regime (corresponding to spin-$1/2$ impurities). Taking into account
RKKY interactions mediated by bulk and edge modes, where the latter cause a
long-range antiferromagnetic Ising coupling, we formulate and solve the
low-energy theory for this two-impurity helical Majorana problem. In
particular, we show that the long-time spin dynamics after a magnetic field
quench displays weakly damped oscillations with universal quality factor.
|
1412.5317v2
|
2015-01-01
|
Orthogonal jumps of wavefunction in white-noise potentials
|
We investigate the evolution of the quantum state for a free particle placed
into a random external potential of white-noise type. The master equation for
the density matrix is derived by means of path integral method. We propose an
equivalent stochastic process where the wavefunction satisfies a nonlinear
Schr\"odinger equation except for random moments at which it shows orthogonal
jumps. The relation of our work to the usual theory of quantum noise and
damping is briefly discussed.
|
1501.00274v1
|
2015-01-04
|
Infinite energy solutions for Dissipative Euler equations in R^2
|
We study the Euler equations with the so-called Ekman damping in the whole 2D
space. The global well-posedness and dissipativity for the weak infinite energy
solutions of this problem in the uniformly local spaces is verified based on
the further development of the weighted energy theory for the Navier-Stokes and
Euler type problems. In addition, the existence of weak locally compact global
attractor is proved and some extra compactness of this attractor is obtained.
|
1501.00684v1
|
2015-01-06
|
New boson realization of the Lipkin model obeying the su(2)-algebra
|
New boson representation of the su(2)-algebra proposed by the present authors
for describing the damped and amplified oscillator is examined in the Lipkin
model as one of simple many-fermion models. This boson representation is
expressed in terms of two kinds of bosons with a certain positive parameter. In
order to describe the case of any fermion number, third boson is introduced.
Through this examination, it is concluded that this representation is well
workable for the boson realization of the Lipkin model in any fermion number.
|
1501.01066v1
|
2015-01-09
|
Comparison of decay of solutions to two compressible approximations to Navier-Stokes equations
|
In this article, we use the decay character of initial data to compare the
energy decay rates of solutions to different compressible approximations to the
Navier-Stokes equations. We show that the system having a nonlinear damping
term has slower decay than its counterpart with an advection-like term.
Moreover, we characterize a set of initial data for which the decay of the
first system is driven by the difference between the full solution and the
solution to the linear part, while for the second system the linear part
provides the decay rate.
|
1501.02105v1
|
2015-01-15
|
Aharonov Bohm effect in 2D topological insulator
|
We present magnetotransport measurements in HgTe quantum well with inverted
band structure, which expected to be a two-dimensional topological insulator
having the bulk gap with helical gapless states at the edge. The negative
magnetoresistance is observed in the local and nonlocal resistance
configuration followed by the periodic oscillations damping with magnetic
field. We attribute such behaviour to Aharonov-Bohm effect due to magnetic flux
through the charge carrier puddles coupled to the helical edge states. The
characteristic size of these puddles is about 100 nm.
|
1501.03652v1
|
2015-01-19
|
Relativistic Lagrangians for the Lorentz-Dirac equation
|
We present two types of relativistic Lagrangians for the Lorentz-Dirac
equation written in terms of an arbitrary world-line parameter. One of the
Lagrangians contains an exponential damping function of the proper time and
explicitly depends on the world-line parameter. Another Lagrangian includes
additional cross-terms consisting of auxiliary dynamical variables and does not
depend explicitly on the world-line parameter. We demonstrate that both the
Lagrangians actually yield the Lorentz-Dirac equation with a source-like term.
|
1501.04551v2
|
2015-01-31
|
Tunneling of atoms, nuclei and molecules
|
This is a brief review of few relevant topics on tunneling of composite
particles and how the coupling to intrinsic and external degrees of freedom
affects tunneling probabilities. I discuss the phenomena of resonant tunneling,
different barriers seen by subsystems, damping of resonant tunneling by level
bunching and continuum effects due to particle dissociation.
|
1502.00074v2
|
2015-01-31
|
Reversible compression of an optical piston through Kramers dynamics
|
We study the reversible crossover between stable and bistable phases of an
over-damped Brownian bead inside an optical piston. The interaction potentials
are solved developing a method based on Kramers' theory that exploits the
statistical properties of the stochastic motion of the bead. We evaluate
precisely the energy balance of the crossover. We show that the deformation of
the optical potentials induced by the compression of the piston is related to a
production of heat which measures the non-adiabatic character of the crossover.
This reveals how specific thermodynamic processes can be designed and
controlled with a high level of precision by tailoring the optical landscapes
of the piston.
|
1502.00173v1
|
2015-02-02
|
Protein viscoelastic dynamics: a model system
|
A model system inspired by recent experiments on the dynamics of a folded
protein under the influence of a sinusoidal force is investigated and found to
replicate many of the response characteristics of such a system. The essence of
the model is a strongly over-damped oscillator described by a harmonic
restoring force for small displacements that reversibly yields to stress under
sufficiently large displacement. This simple dynamical system also reveals
unexpectedly rich behavior, exhibiting a series of dynamical transitions and
analogies with equilibrium thermodynamic phase transitions. The effects of
noise and of inertia are briefly considered and described.
|
1502.00343v1
|
2015-02-09
|
Large amplitude oscillation of magnetization in spin-torque oscillator stabilized by field-like torque
|
Oscillation frequency of spin torque oscillator with a perpendicularly
magnetized free layer and an in-plane magnetized pinned layer is theoretically
investigated by taking into account the field-like torque. It is shown that the
field-like torque plays an important role in finding the balance between the
energy supplied by the spin torque and the dissipation due to the damping,
which results in a steady precession. The validity of the developed theory is
confirmed by performing numerical simulations based on the
Landau-Lifshitz-Gilbert equation.
|
1502.02699v1
|
2015-02-15
|
Percolation and jamming transitions in particulate systems with and without cohesion
|
We consider percolation and jamming transitions for particulate systems
exposed to compression. For the systems built of particles interacting by
purely repulsive forces in addition to friction and viscous damping, it is
found that these transitions are influenced by a number of effects, and in
particular by the compression rate. In a quasi-static limit, we find that for
the considered type of interaction between the particles, percolation and
jamming transitions coincide. For cohesive systems, however, or for any system
exposed to even slow dynamics, the differences between the considered
transitions are found and quantified.
|
1502.04389v4
|
2015-02-16
|
Novel relativistic plasma excitations in a gated two-dimensional electron system
|
The microwave response of a two-dimensional electron system (2DES) covered by
a conducting top gate is investigated in the relativistic regime for which the
2D conductivity $\sigma_{2 \rm{D}} > c/2\pi$. Weakly damped plasma waves are
excited in the gated region of the 2DES. The frequency and amplitude of the
resulting plasma excitations show a very unusual dependence on the magnetic
field, conductivity, gate geometry and separation from the 2DES. We show that
such relativistic plasmons survive for temperatures up to 300 K, allowing for
new room-temperature microwave and terahertz applications.
|
1502.04457v1
|
2015-02-22
|
Fractional extension of Kramers rate and barrier escaping from metastable potential well
|
The reactive process of barrier escaping from the metastable potential well
is studied together with the extension of Kramers' rate formula to the
fractional case. Characteristic quantities are computed for an thimbleful of
insight into the near barrier escaping and recrossing dynamics. Where the
stationary transmission coefficient is revealed to be larger than the usual
cases which implies less barrier recrossing. And the non-monotonic varying of
it reveals a close dependence to the fractional exponent $\alpha$. In most
cases, the near barrier behavior of the escaping dynamics is equivalent to the
diffusion in the two-dimensional non-Ohmic damping system.
|
1502.06184v1
|
2015-03-03
|
Discretization of the 3D Monge-Ampere operator, between Wide Stencils and Power Diagrams
|
We introduce a monotone (degenerate elliptic) discretization of the
Monge-Ampere operator, on domains discretized on cartesian grids. The scheme is
consistent provided the solution hessian condition number is uniformly bounded.
Our approach enjoys the simplicity of the Wide Stencil method, but
significantly improves its accuracy using ideas from discretizations of optimal
transport based on power diagrams. We establish the global convergence of a
damped Newton solver for the discrete system of equations. Numerical
experiments, in three dimensions, illustrate the scheme efficiency.
|
1503.00947v1
|
2015-03-04
|
Geodesic Acoustic Mode in Toroidally Rotating Anisotropic Tokamaks
|
Effects of anisotropy on the geodesic acoustic mode (GAM) is analyzed by
using gyro-kinetic equations applicable to low-frequency microinstabilities in
a toroidally rotating tokamak plasma. Dispersion relation in the presence of
arbitrary Mach number $M$, anisotropy strength $\sigma$, and the temperature
ration $\tau$ is analytically derived. It is shown that when $\sigma$ is less
than $ 3 + 2 \tau$, the increased electron temperature with fixed ion parallel
temperature increases the normalized GAM frequency. When $\sigma$ is larger
than $ 3 + 2 \tau$, the increasing of electron temperature decreases the GAM
frequency. The anisotropy $\sigma$ always tends to enlarge the GAM frequency.
The Landau damping rate is dramatically decreased by the increasing $\tau$ or
$\sigma$.
|
1503.01315v1
|
2015-03-06
|
Dynamical bifurcation of multi-frequency oscillations in a fast-slow system
|
We study a dynamical counterpart of bifurcation to invariant torus for a
system of interconnected fast phase variables and slowly varying parameters. We
show that in such a system, due to the slow evolution of parameters, there
arise transient processes from damping oscillations to multi-frequency ones,
asymptotically close to motions on the invariant torus.
|
1503.02000v2
|
2015-03-12
|
Control of current-induced spin-orbit effects in a ferromagnetic heterostructure by electric field
|
We study the effects of electrostatic gating on the current-induced phenomena
in ultrathin ferromagnet/heavy metal heterostructures. We utilize heterodyne
detection and analysis of symmetry with respect to the direction of the
magnetic field to separate electric field contributions to the magnetic
anisotropy, current-induced field-like torque, and damping torque. Analysis of
the electric field effects allows us to estimate the Rashba and the spin Hall
contributions to the current-induced phenomena. Electrostatic gating can
provide insight into the spin-orbit phenomena, and enable new functionalities
in spintronic devices.
|
1503.03882v1
|
2015-03-16
|
Determining a boundary coefficient in a dissipative wave equation: Uniqueness and directional lipschitz stability
|
We are concerned with the problem of determining the damping boundary
coefficient appearing in a dissipative wave equation from a single boundary
measurement. We prove that the uniqueness holds at the origin provided that the
initial condition is appropriately chosen. We show that the choice of the
initial condition leading to uniqueness is related to a fine version of unique
continuation property for elliptic operators. We also establish a Lipschitz
directional stability estimate at the origin, which is obtained by a
linearization process.
|
1503.04528v1
|
2015-03-16
|
The Open-System Dicke-Model Quantum Phase Transition with a Sub-Ohmic Bath
|
We show that the critical exponent of a quantum phase transition in a
damped-driven open system is determined by the spectral density function of the
reservoir. We consider the open-system variant of the Dicke model, where the
driven boson mode and also the large N-spin couple to independent reservoirs at
zero temperature. The critical exponent, which is $1$ if there is no spin-bath
coupling, decreases below 1 when the spin couples to a sub-Ohmic reservoir.
|
1503.04672v1
|
2015-03-24
|
On nonlinearity implications and wind forcing in Hasselmann equation
|
We discuss several experimental and theoretical techniques historically used
for Hasselmann equation wind input terms derivation. We show that recently
developed ZRP technique in conjunction with high-frequency damping without
spectral peak dissipation allows to reproduce more than a dozen of
fetch-limited field experiments. Numerical simulation of the same Cauchy
problem for different wind input terms has been performed to discuss
nonlinearity implications as well as correspondence to theoretical predictions.
|
1503.07091v2
|
2015-03-29
|
Energy decay for linear dissipative wave equations in exterior domains
|
In earlier works, we have shown the uniform decay of the local energy of the
damped wave equation in exterior domain when the damper is spatially localized
near captive rays. In order to have uniform decay of the total energy, the
damper has also to act at space infinity. In this work, we establish uniform
decay of both the local and global energies. The rates of decay turns out to be
the same as those for the heat equation, which shows that an effective damper
at space infinity strengthens the parabolic structure in the equation.
|
1503.08373v1
|
2015-03-31
|
Potential performance for Pb-Pb, p-Pb and p-p collisions in a future circular collider
|
The hadron collider studied in the Future Circular Collider (FCC) project
could operate with protons and lead ions in similar operation modes as the LHC.
In this paper the potential performances in lead-lead, proton-lead and
proton-proton collisions are investigated. Based on average lattice parameters,
the strengths of intra-beam scattering and radiation damping are evaluated and
their effect on the beam and luminosity evolution is presented. Estimates for
the integrated luminosity per fill and per run are given, depending on the
turnaround time. Moreover, the beam-beam tune shift and bound free pair
production losses in heavy-ion operation are addressed.
|
1503.09107v1
|
2015-04-02
|
Real-time emission spectrum of a hybrid atom-optomechanical cavity
|
We theoretically investigate the real-time emission spectrum of a two-level
atom coupled to an optomechanical cavity (OMC). Using quantum trajectory
approach we obtain the single-photon time-dependent spectrum in this hybrid
system where the influence of a strong atom-cavity coupling and a strong
optomechanical interaction are studied. We find a dressed state picture can
explain the spectra by predicting the exact peak locations as well as the
relative peak heights. In our analysis we also include the effect of mechanical
losses (under weak mechanical damping limit) and single-photon loss through
spontaneous emission from the two-level emitter.
|
1504.00443v1
|
2015-04-09
|
Drift wave stabilized by an additional streaming ion or plasma population
|
It is shown that the universally unstable kinetic drift wave in an
electron-ion plasma can very effectively be suppressed by adding an extra
flowing ion (or plasma) population. The effect of the flow of the added ions is
essential, their response is of the type (vph-vf0) exp[-(vph-vf0)^2], where vf0
is the flow speed and vph phase speed parallel to the magnetic field vector.
The damping is strong and it is mainly due to this ion exponential term, and
this remains so for vf0 < vph.
|
1504.02507v1
|
2015-04-21
|
Exchange effects in a cold plasma
|
We have studied the exchange corrections to linear electrostatic wave
propagation in a plasma using a quantum kinetic formalism. Specifically we have
considered the zero temperature limit. In order to simplify the calculations we
have focused on the long wavelength limit, i.e. wavelengths much longer than
the de Broglie wavelength. For the case of ion-acoustic waves we have
calculated the exchange correction both to the damping rate and the real part
of the frequency. For Langmuir waves the frequency shift due to exchange
effects is found. Our results are compared with the frequency shifts deduced
from commonly used exchange potentials which are computed from density
functional theory.
|
1504.05339v1
|
2015-04-28
|
Fractional relaxation and fractional oscillation models involving Erdelyi-Kober integrals
|
We consider fractional relaxation and fractional oscillation equations
involving Erdelyi-Kober integrals. In terms of Riemann-Liouville integrals, the
equations we analyze can be understood as equations with time-varying
coefficients. Replacing Riemann-Liouville integrals with Erdelyi-Kober-type
integrals in certain fractional oscillation models, we obtain some more general
integro-differential equations. The corresponding Cauchy-type problems can be
solved numerically, and, in some cases analytically, in terms of Saigo-Kilbas
Mittag-Leffler functions. The numerical results are obtained by a treatment
similar to that developed by K. Diethelm and N.J. Ford to solve the
Bagley-Torvik equation. Novel results about the numerical approach to the
fractional damped oscillator equation with time-varying coefficients are also
presented.
|
1504.07568v1
|
2015-05-09
|
Aftershocks and Omori's law in a modified Carlson-Langer model with nonlinear visco-elasticity
|
A modified Carlson-Langer model for earthquakes is proposed, which includes
nonlinear visco-elasticity. Several aftershocks are generated after the main
shock owing to the damping of the additional visco-elastic force. Both the
Gutenberg-Richter law and Omori's law are reproduced in a numerical simulation
of the modified Carlson-Langer model on a critical percolation cluster of a
square lattice.
|
1505.02225v1
|
2015-05-20
|
Counterflow in a doubly superfluid mixture of Bosons and Fermions
|
In this article, we calculate the friction between two counter-flowing
bosonic and fermionic super-fluids. In the limit where the boson-boson and
boson-fermion interactions can be treated within the mean-field approximation,
we show that the force can be related to the dynamical structure factor of the
fermionic component. Finally, we provide asymptotic expressions for weakly and
strongly attractive fermions and show that the damping rate obeys simple
scaling laws close to the critical velocity.
|
1505.05370v1
|
2015-05-22
|
Long time dynamics for damped Klein-Gordon equations
|
For general nonlinear Klein-Gordon equations with dissipation we show that
any finite energy radial solution either blows up in finite time or
asymptotically approaches a stationary solution in $H^1\times L^2$. In
particular, any global solution is bounded. The result applies to standard
energy subcritical focusing nonlinearities $|u|^{p-1} u$,
$1\textless{}p\textless{}(d+2)/(d-2)$ as well as any energy subcritical
nonlinearity obeying a sign condition of the Ambrosetti-Rabinowitz type. The
argument involves both techniques from nonlinear dispersive PDEs and dynamical
systems (invariant manifold theory in Banach spaces and convergence theorems).
|
1505.05981v1
|
2015-05-25
|
General decay for a viscoelastic wave equation with dynamic boundary conditions and a time-varying delay
|
The goal of this paper is to study a nonlinear viscoelastic wave equation
with strong damping, time-varying delay and dynamical boundary condition. By
introducing suitable energy and Lyapunov functionals, under suitable
assumptions, we then prove a general decay result of the energy, from which the
usual exponential and polynomial decay rates are only special cases.
|
1505.07060v6
|
2015-05-28
|
Mixed timestepping schemes for nonsmooth mechanics with high frequency damping
|
This work deals with the integration of nonsmooth flexible multibody systems
with impacts and dry friction. We develop a framework which improves a
non-impulsive trajectory of state variables by impulsive correction after each
time-step if necessary. This correction is automatic and is evaluated on the
same kinematic level as the piecewise non-impulsive trajectory. The resulting
overall mixed timestepping scheme is consistent with respect to impacts and
friction as well as benefits from advantages of the base integration schemes
used to calculate the approximation inside the time-step. Therefore, we compare
the generalized-$\alpha$ method, the Bathe method and the ED-$\alpha$ method.
|
1505.07666v2
|
2015-06-02
|
Current-Driven Motion of Magnetic Domain Wall with Many Bloch Lines
|
The current-driven motion of a domain wall (DW) in a ferromagnet with many
Bloch lines (BLs) via the spin transfer torque is studied theoretically. It is
found that the motion of BLs changes the current-velocity ($j$-$v$)
characteristic dramatically. Especially, the critical current density to
overcome the pinning force is reduced by the factor of the Gilbert damping
coefficient $\alpha$ even compared with that of a skyrmion. This is in sharp
contrast to the case of magnetic field driven motion, where the existence of
BLs reduces the mobility of the DW.
|
1506.00723v1
|
2015-06-04
|
Stabilization of transverse vibrations of an inhomogeneous Euler- Bernoulli beam with a thermal effect
|
We consider an inhomogeneous Euler-Bernoulli (EB) beam of length $L$ clamped
at both ends and subject to : an external frictional damping and a thermal
effect (Fourier law). We prove the well-posedness of the model and analyze the
behavior of the solution as $t \rightarrow + \infty.$ The existence is proved
using semigroup theory, and the exponential stabilization of solutions is
obtained considering multiplier technique. A numerical illustration of the
energy decay is given, based on initial data close to a real physical
experiment.
|
1506.01659v2
|
2015-06-23
|
Electronic friction-based vibrational lifetimes of molecular adsorbates: Beyond the independent atom approximation
|
We assess the accuracy of vibrational damping rates of diatomic adsorbates on
metal surfaces as calculated within the local-density friction approximation
(LDFA). An atoms-in-molecules (AIM) type charge partitioning scheme accounts
for intra-molecular contributions and overcomes the systematic underestimation
of the non-adiabatic losses obtained within the prevalent independent atom
approximation. The quantitative agreement obtained with theoretical and
experimental benchmark data suggests the LDFA-AIM as an efficient and reliable
approach to account for electronic dissipation in ab initio molecular dynamics
simulations of surface chemical reactions.
|
1506.06877v1
|
2015-06-23
|
Global small solutions to a tropical climate model without thermal diffusion
|
We obtain the global well-posedness of classical solutions to a tropical
climate model derived by Feireisl-Majda-Pauluis in \cite{FMP} with only the
dissipation of the first baroclinic model of the velocity ($-\eta \Delta v$)
under small initial data. The main difficulty is the absence of thermal
diffusion as the work by Li-Titi in \cite{LT}. To overcome it, we exploit the
structure of the equations coming from the coupled terms, dissipation term and
damp term. Then we find the hidden thermal diffusion. In addition, based on the
Littlewood-Palay theory, we establish a generalized commutator estimate, which
may be applied to other partial differential equations.
|
1506.06930v2
|
2015-07-03
|
Remote control of self-assembled microswimmers
|
Physics governing the locomotion of microorganisms and other microsystems is
dominated by viscous damping. An effective swimming strategy involves the
non-reciprocal and periodic deformations of the considered body. Here, we show
that a magnetocapillary-driven self-assembly, composed of three soft
ferromagnetic beads, is able to swim along a liquid-air interface when powered
by an external magnetic field. More importantly, we demonstrate that
trajectories can be fully controlled, opening ways to explore low Reynolds
number swimming. This magnetocapillary system spontaneously forms by
self-assembly, allowing miniaturization and other possible applications such as
cargo transport or solvent flows.
|
1507.00865v1
|
2015-07-08
|
From semiclassical Strichartz estimates to uniform $L^p$ resolvent estimates on compact manifolds
|
We prove uniform $L^p$ resolvent estimates for the stationary damped wave
operator. The uniform $L^p$ resolvent estimates for the Laplace operator on a
compact smooth Riemannian manifold without boundary were first established by
Dos Santos Ferreira-Kenig-Salo and advanced further by Bourgain-Shao-Sogge-Yao.
Here we provide an alternative proof relying on the techniques of semiclassical
Strichartz estimates. This approach allows us also to handle non-self-adjoint
perturbations of the Laplacian and embeds very naturally in the semiclassical
spectral analysis framework.
|
1507.02307v3
|
2015-07-31
|
Well-posedness and general decay of solution for a transmission problem with viscoelastic term and delay
|
In this paper, we consider a transmission problem in a bounded domain with a
viscoelastic term and a delay term. Under appropriate hypothesis on the
relaxation function and the relationship between the weight of the damping and
the weight of the delay, we prove the well-posedness result by using
Faedo-Galerkin method. By introducing suitable Lyaponov functionals, we
establish a general decay result, from which the exponential and polynomial
types of decay are only special cases.
|
1507.08855v1
|
2015-08-05
|
Qualitative properties of solutions for nonlinear Schrödinger equations with nonlinear boundary conditions on the half-line
|
In this paper, we study the interaction between a nonlinear focusing Robin
type boundary source, a nonlinear defocusing interior source, and a weak
damping term for nonlinear Schr\"odinger equations posed on the infinite half
line. We construct solutions with negative initial energy satisfying a certain
set of conditions which blow-up in finite time in the $H^1$-sense. We obtain a
sufficient condition relating the powers of nonlinearities present in the model
which allows construction of blow-up solutions. In addition to the blow-up
property, we also discuss the stabilization property and the critical exponent
for this model.
|
1508.01043v1
|
2015-08-12
|
Direct Characterization of Quantum Dynamics with Noisy Ancilla
|
We present methods for the direct characterization of quantum dynamics (DCQD)
in which both the principal and ancilla systems undergo noisy processes. Using
a concatenated error detection code, we discriminate between located and
unlocated errors on the principal system in what amounts to filtering of
ancilla noise. The example of composite noise involving amplitude damping and
depolarizing channels is used to demonstrate the method, while we find the rate
of noise filtering is more generally dependent on code distance. Our results
indicate the accuracy of quantum process characterization can be greatly
improved while remaining within reach of current experimental capabilities.
|
1508.03053v1
|
2015-08-19
|
Absorption in dipole-lattice models of dielectrics
|
We develop a classical microscopic model of a dielectric. The model features
nonlinear interaction terms between polarizable dipoles and lattice vibrations.
The lattice vibrations are found to act as a pseudo-reservoir, giving broadband
absorption of electromagnetic radiation without the addition of damping terms
in the dynamics. The effective permittivity is calculated using a perturbative
iteration method and is found to have the form associated with real
dielectrics. Spatial dispersion is naturally included in the model and we also
calculate the wavevector dependence of the permittivity.
|
1508.04666v2
|
2015-09-06
|
New approach for solving master equation of open atomic system
|
We describe a new approach called Ket-Bra Entangled State (KBES) Method which
enables one convert master equations into Schr\"odinger-like equation. In
sharply contrast to the super-operator method, the KBES method is applicable
for any master equation of finite-level system in theory, and the calculation
can be completed by computer. With this method, we obtain the exact dynamic
evolution of a radioactivity damped 2-level atom in time-dependent external
field, and a 3-level atom coupled with bath; Moreover, the master equation of
N-qubits Heisenberg chain each qubit coupled with a reservoir is also resolved
in Sec.III; Besides, the paper briefly discuss the physical implications of the
solution.
|
1509.01775v1
|
2015-09-10
|
Half-space Kinetic Equations with General Boundary Conditions
|
We study half-space linear kinetic equations with general boundary conditions
that consist of both given incoming data and various type of reflections,
extending our previous work [LLS14] on half-space equations with incoming
boundary conditions. As in [LLS14], the main technique is a damping
adding-removing procedure. We establish the well-posedness of linear (or
linearized) half-space equations with general boundary conditions and
quasi-optimality of the numerical scheme. The numerical method is validated by
examples including a two-species transport equation, a multi-frequency
transport equation, and the linearized BGK equation in 2D velocity space.
|
1509.03225v1
|
2015-09-14
|
Squeezed light and correlated photons from dissipatively coupled optomechanical systems
|
We study theoretically the squeezing spectrum and second-order correlation
function of the output light for an optomechanical system in which a mechanical
oscillator modulates the cavity linewidth (dissipative coupling). We find
strong squeezing coinciding with the normal-mode frequencies of the linearized
system. In contrast to dispersive coupling, squeezing is possible in the
resolved-sideband limit simultaneously with sideband cooling. The second-order
correlation function shows damped oscillations, whose properties are given by
the mechanical-like, the optical-like normal mode, or both, and can be below
shot-noise level at finite times, $g^{(2)} (\tau) < 1$.
|
1509.04041v2
|
2015-09-14
|
Spin Transport in Antiferromagnetic Insulators Mediated by Magnetic Correlations
|
We report a systematic study of spin transport in antiferromagnetic (AF)
insulators having a wide range of ordering temperatures. Spin current is
dynamically injected from Y3Fe5O12 (YIG) into various AF insulators in
Pt/insulator/YIG trilayers. Robust, long-distance spin transport in the AF
insulators is observed, which shows strong correlation with the AF ordering
temperatures. We find a striking linear relationship between the spin decay
length in the AFs and the damping enhancement in YIG, suggesting the critical
role of magnetic correlations in the AF insulators as well as at the AF/YIG
interfaces for spin transport in magnetic insulators.
|
1509.04336v1
|
2015-09-18
|
Asymptotic for a second order evolution equation with convex potential and vanishing damping term
|
In this short note, we recover by a different method the new result due to
Attouch, Peyrouqet and Redont concerning the weak convergence as
$t\rightarrow+\infty$ of solutions $x(t)$ to the second order differential
equation \[ x^{\prime\prime}(t)+\frac{K}{t}x^{\prime}(t)+\nabla\Phi(x(t))=0, \]
where $K>3$ and $\Phi$ is a smooth convex function defined on an Hilbert Space
$\mathcal{H}.$ Moreover, we improve slightly their result on the rate of
convergence of $\Phi(x(t))-\min\Phi.$
|
1509.05598v2
|
2015-09-29
|
A versatile PMT test bench and its application in the DAMPE-PSD
|
A versatile test bench system, dedicated for massive PMT characterization, is
developed at the Institute of Modern Physics, Chinese Academy of Sciences. It
can perform many test contents with large capacity and high level of
automation, and the migration from one testing configuration to another is
lightweight and time-saving. This system has been used in the construction of
the Plastic Scintillator Detector of DArk Matter Particle Explorer already, and
a total of 570 Hamamatsu R4443 tubes have been tested successfully.
|
1509.08739v1
|
2015-10-09
|
Effect of ion polarization on longitudinal excitations in ionic melts
|
A simplified model for a collective dynamics in ionic melts is proposed for
the description of optic-like excitations. Within a polarization model of ionic
melt the analytical expressions for optic and relaxation dipole modes are
obtained. The considered model allows one to describe a softening of frequency
and an increase of damping of optic modes caused by polarization processes in
comparison with the rigid-ion model. The contributions related with ion
polarization to time correlation functions are calculated.
|
1510.02599v1
|
2015-10-16
|
The invariant polarisation-tensor field for deuterons in storage rings and the Bloch equation for the polarisation-tensor density
|
I extend and update earlier work, summarised in [1], whereby the invariant
polarisation-tensor field (ITF) for deuterons in storage rings was introduced
to complement the invariant spin field (ISF). Taken together, the ITF and the
ISF provide a definition of the equilibrium spin density-matrix field which, in
turn, offers a clean framework for describing equilibrium spin-1 ensembles in
storage rings. I show how to construct the ITF by stroboscopic averaging, I
give examples, I discuss adiabatic invariance and I introduce a formalism for
describing the effect of noise and damping.
|
1510.04936v3
|
2015-10-23
|
A random dynamical systems perspective on stochastic resonance
|
We study stochastic resonance in an over-damped approximation of the
stochastic Duffing oscillator from a random dynamical systems point of view. We
analyse this problem in the general framework of random dynamical systems with
a nonautonomous forcing. We prove the existence of a unique global attracting
random periodic orbit and a stationary periodic measure. We use the stationary
periodic measure to define an indicator for the stochastic resonance.
|
1510.06973v1
|
2015-10-26
|
PMU-Based Estimation of Dynamic State Jacobian Matrix
|
In this paper, a hybrid measurement and model-based method is proposed which
can estimate the dynamic state Jacobian matrix in near real-time. The proposed
method is computationally efficient and robust to the variation of network
topology. Since the estimated Jacobian matrix carries significant information
on system dynamics and states, it can be utilized in various applications. In
particular, two application of the estimated Jacobian matrix in online
oscillation analysis, stability monitoring and control are illustrated with
numerical examples. In addition, a side-product of the proposed method can
facilitate model validation by approximating the damping of generators.
|
1510.07603v1
|
2015-10-29
|
Random Perturbations of a Periodically Driven Nonlinear Oscillator: Escape from a resonance zone
|
The phase space for a periodically driven nonlinear oscillator consists of
many resonance zones. Let the strength of periodic excitation and the strength
of the damping be indexed by a small parameter $\varepsilon$. It is well known
that, as $\varepsilon \to 0$, the measure of the set of initial conditions
which lead to 'capture in a resonance zone' goes to zero. In this paper we
study the effect of weak noise on the escape from a resonance zone.
|
1510.08919v2
|
2015-11-07
|
Experimental simulation of decoherence in photonics qudits
|
We experimentally perform the simulation of open quantum dynamics in
single-qudit systems. Using a spatial light modulator as a dissipative optical
device, we implement dissipative-dynamical maps onto qudits encoded in the
transverse momentum of spontaneous parametric down-converted photon pairs. We
show a well-controlled technique to prepare entangled qudits states as well as
to implement dissipative local measurements; the latter realize two specific
dynamics: dephasing and amplitude damping. Our work represents a new
analogy-dynamical experiment for simulating an open quantum system.
|
1511.02355v1
|
2015-11-10
|
Dispersion of Volume Relativistic Magnetoplasma Excitation in a Gated Two-Dimensional Electron System
|
The dispersion of the volume relativistic magnetoplasma mode in a gated
GaAs/AlGaAs quantum well is measured using a coupled resonators detection
technique. The weakly damped relativistic mode exhibits an unusual
zigzag-shaped magnetodispersion dependence dictated by the diagonal component
of the resistivity tensor $\rho_{xx}$. The plasma excitation easily hybridizes
with photon modes due to a large spatial delocalization of its electromagnetic
field. The effects of electron density and structure geometry on the excitation
spectrum have been investigated.
|
1511.03002v1
|
2015-11-11
|
The two-qubit amplitude damping channel: characterization using quantum stabilizer codes
|
A protocol based on quantum error correction based characterization of
quantum dynamics (QECCD) is developed for quantum process tomography on a
two-qubit system interacting dissipatively with a vacuum bath. The method uses
a 5-qubit quantum error correcting code that corrects arbitrary errors on the
first two qubits, and also saturates the quantum Hamming bound. The dissipative
interaction with a vacuum bath allows for both correlated and independent noise
on the two-qubit system. We study the dependence of the degree of the
correlation of the noise on evolution time and inter-qubit separation.
|
1511.03368v1
|
2015-11-17
|
Device independent witnessing of unknown quantum channels
|
Quantum process tomography, the standard procedure to characterize any
quantum channel in nature, is affected by a circular argument: in order to
characterize the channel, the tomographic preparation and measurement need in
turn to be already characterized. We break this loop by designing an
operational framework able to optimally characterize any given unknown quantum
channel in a device-independent fashion, namely, by only looking at its
input-output statistics, under the sole assumption that quantum theory is
valid. We provide explicit solutions, in closed form, for practically relevant
cases such as the erasure, depolarizing, and amplitude-damping channels.
|
1511.05260v2
|
2015-11-20
|
Non-Markovianity through Multipartite Correlation Measures
|
We provide a characterization of memory effects in non-Markovian system-bath
interactions from a quantum information perspective. More specifically, we
establish sufficient conditions for which generalized measures of multipartite
quantum, classical, and total correlations can be used to quantify the degree
of non-Markovianity of a local quantum decohering process. We illustrate our
results by considering the dynamical behavior of the trace-distance
correlations in multi-qubit systems under local dephasing and generalized
amplitude damping.
|
1511.06788v2
|
2015-12-01
|
Percolation, sliding, localization and relaxation in topologically closed circuits
|
Considering a "random walk in a random environment" in a topologically closed
circuit, we explore the implications of the percolation and sliding transitions
for its relaxation modes. A complementary question regarding the
"delocalization" of eigenstates of non-hermitian Hamiltonians has been
addressed by Hatano, Nelson, and followers. But we show that for a conservative
stochastic process the implied spectral properties are dramatically different.
In particular we determine the threshold for under-damped relaxation, and
observe "complexity saturation" as the bias is increased.
|
1512.00258v2
|
2015-12-08
|
Existence of invariant measures for the stochastic damped KdV equation
|
We address the long time behavior of solutions of the stochastic Korteweg-de
Vries equation $ du + (\partial^3_x u +u\partial_x u +\lambda u)dt = f dt+\Phi
dW_t$ on ${\mathbb R}$ where $f$ is a deterministic force. We prove that the
Feller property holds and establish the existence of an invariant measure. The
tightness is established with the help of the asymptotic compactness, which is
carried out using the Aldous criterion.
|
1512.02686v2
|
2015-12-10
|
Construction of ODE systems from time series data by a highly flexible modelling approach
|
In this paper, a down-to-earth approach to purely data-based modelling of
unknown dynamical systems is presented. Starting from a classical, explicit ODE
formulation $y' = f(t,y)$ of a dynamical system, a method determining the
unknown right-hand side $f(t,y)$ from some trajectory data $y_{k}(t_{j})$,
possibly very sparse, is given. As illustrative examples, a semi-standard
predator-prey model is reconstructed from a data set describing the population
numbers of hares and lynxes over a period of twenty years, and a simple damped
pendulum system with a highly non-linear right-hand side is recovered from some
artificial but very sparse data.
|
1512.03357v1
|
2015-12-10
|
Damping and Decoherence in Neutron Oscillations
|
An analysis is made of the role played by the gas environment in
neutron-mirror-neutron and neutron-antineutron oscillations. In the first
process the interaction with the ambient medium induces a refraction energy
shift which plays the role of an extra magnetic field. In the second process
antineutron annihilation in practice might lead to strong decoherence, which
should be taken into account in experiments with free neutrons looking for the
neutron to antineutron transformation.
|
1512.03398v1
|
2015-12-14
|
Oscillation: The Key For Understanding Strange Radio Behaviors Of AXP/SGRs
|
We suggest stellar oscillations are responsible for the strange radio
behaviors of Anomalous X-ray pulsars and soft Gamma-ray repeaters (AXP/SGRs),
within the framework of both solid quark star model and magnetar model. In
solid quark star model, the extra voltage provided by oscillations activates
the star from under death line to above death line. In magnetar model,
oscillations enlarge the radio beam so that increase the possibility to detect
it. Later radio emission decays and vanishes as oscillations damp.
|
1512.04609v1
|
2015-12-15
|
Changing character of electronic transitions in graphene: From single particle excitations to plasmons
|
In this paper we clarify the nature of $\pi$ and $\pi+\sigma$ electron
excitations in pristine graphene. We clearly demonstrate the continuous
transition from single particle to collective character of such excitations and
how screening modifies their dispersion relations. We prove that $\pi$ and
$\pi+\sigma$ plasmons do exist in graphene, though occurring only for a
particular range of wavevectors and with finite damping rate. The particular
attention is paid to compare the theoretical results with available EELS
measurements in optical ($\mathrm{Q\approx 0}$) and other ($\mathrm{Q\neq 0}$)
limits. The conclusions, based on microscopic numerical results, are confirmed
in an approximate analytical approach.
|
1512.04775v1
|
2015-12-30
|
Black-body radiation for twist-deformed space-time
|
In this article we formally investigate the impact of twisted space-time on
black-body radiation phenomena, i.e. we derive the $\theta$-deformed Planck
distribution function as well as we perform its numerical integration to the
$\theta$-deformed total radiation energy. In such a way we indicate that the
space-time noncommutativity very strongly damps the black-body radiation
process. Besides we provide for small parameter $\theta$ the twisted
counterparts of Rayleigh-Jeans and Wien distributions respectively.
|
1512.08859v1
|
2016-01-07
|
Quasiparticle states driven by a scattering on the preformed electron pairs
|
We analyze evolution of the single particle excitation spectrum of the
underdoped cuprate superconductors near the anti-nodal region, considering
temperatures below and and above the phase transition. We inspect the
phenomenological self-energy that reproduces the
angle-resolved-photoemission-spectroscopy (ARPES) data and we show that above
the critical temperature, such procedure implies a transfer of the spectral
weight from the Bogoliubov-type quasiparticles towards the in-gap damped
states. We also discuss some possible microscopic arguments explaining this
process.
|
1601.01592v2
|
2016-01-11
|
A note on one-way quantum deficit and quantum discord
|
One-way quantum deficit and quantum discord are two important measures of
quantum correlations. We revisit the relationship between them in two-qubit
systems. We investigate the conditions that both one-way quantum deficit and
quantum discord have the same optimal measurement ensembles, and demonstrate
that one-way quantum deficit can be derived from the quantum discord for a
class of X states. Moreover, we give an explicit relation between one-way
quantum deficit and entanglement of formation. We show that under phase damping
channel both one-way quantum deficit and quantum discord evolve exactly in the
same way for four parameters X states. Some examples are presented in details.
|
1601.02313v1
|
2016-01-11
|
Motion of an optically torqued nanorod: the overdamped case
|
A recent experiment [W. A. Shelton {\emph{et\ al.}}, Phys.\ Rev.\ E
{\bf{71}}, 036204 (2005)] measured the response of a nanorod trapped in a
viscous fluid to the torque produced by an incident optical frequency
electromagnetic wave. The nonlinear differential equation describing this
motion is similar that of a damped, driven pendulum. The overdamped limit of
this equation has been solved analytically. We analyze the properties of this
solution in comparison to the observations of the experiment and find very
close agreement.
|
1601.03062v1
|
2016-01-23
|
Nonlinear magnetization dynamics of antiferromagnetic spin resonance induced by intense terahertz magnetic field
|
We report on the nonlinear magnetization dynamics of a HoFeO3 crystal induced
by a strong terahertz magnetic field resonantly enhanced with a split ring
resonator and measured with magneto-optical Kerr effect microscopy. The
terahertz magnetic field induces a large change (~40%) in the spontaneous
magnetization. The frequency of the antiferromagnetic resonance decreases in
proportion to the square of the magnetization change. A modified
Landau-Lifshitz-Gilbert equation with a phenomenological nonlinear damping term
quantitatively reproduced the nonlinear dynamics.
|
1601.06213v1
|
2016-01-28
|
Gap plasmonics of silver nanocube dimers
|
We theoretically investigate gap plasmons for two silver nanocubes coupled
through a molecular tunnel junction. In absence of tunneling, the red-shift of
the bonding mode saturates with decreasing gap distance. Tunneling at small gap
distances leads to a damping and slight blue-shift of the bonding mode, but no
low-energy charge transfer plasmon mode appears in the spectra. This finding is
in stark contrast to recent work of Tan et al. [Science 343, 1496 (2014)].
|
1601.07689v1
|
2016-02-01
|
Underdamped stochastic heat engine at maximum efficiency
|
We investigate the performance of an underdamped stochastic heat engine for a
time-dependent harmonic oscillator. We analytically determine the optimal
protocol that maximizes the efficiency at fixed power. The maximum efficiency
reduces to the Curzon-Ahlborn formula at maximum power and the Carnot formula
at zero power. We further establish that the efficiency at maximum power is
universally given by the Curzon-Ahlborn efficiency in the weakly damped regime.
Finally, we show that even small deviations from operation at maximum power may
result in a significantly increased efficiency.
|
1602.00392v1
|
2016-02-05
|
Blow up property for viscoelastic evolution equations on manifolds with conical degeneration
|
This paper is concerned with the study of the nonlinear viscoelastic
evolution equation with strong damping and source terms, described by \[u_{tt}
- \Delta_{\mathbb{B}}u + \int_{0}^{t}g(t-\tau)\Delta_{\mathbb{B}}u(\tau)d\tau +
f(x)u_{t}|u_{t}|^{m-2} = h(x)|u|^{p-2}u , \hspace{1 cm} x\in int\mathbb{B}, t >
0,\] where $\mathbb{B}$ is a stretched manifold. First, we prove the solutions
of problem {1.1} in cone Sobolev space
$\mathcal{H}^{1,\frac{n}{2}}_{2,0}(\mathbb{B}),$ admit a blow up in finite time
for $p > m$ and positive initial energy. Then, we construct a lower bound for
obtained blow up time under appropriate assumptions on data.
|
1602.02593v1
|
2016-02-20
|
Synchronization of two couple pendula in absence of escapement
|
A model of two oscillating pendula placed on a mobile support is studied.
Once an overall scheme of equations, under general assumptions, is formulated
via the Lagrangian equations of motion, the specific case of absence of
escapement is examined. The mechanical models consists of two coupled pendula
both oscillating on a moving board attached to a spring. The final result
performs a selection among the peculiar parameters of the physical process
(lenghts, ratio of masses, friction and damping coefficients, stiffness of the
spring) which provide a tendency to synchronization.
|
1602.06382v1
|
2016-02-22
|
Exchange magnon induced resistance asymmetry in permalloy spin-Hall oscillators
|
We investigate magnetization dynamics in a spin-Hall oscillator using a
direct current measurement as well as conventional microwave spectrum analysis.
When the current applies an anti-damping spin-transfer torque, we observe a
change in resistance which we ascribe to the excitation of incoherent exchange
magnons. A simple model is developed based on the reduction of the effective
saturation magnetization, quantitatively explaining the data. The observed
phenomena highlight the importance of exchange magnons on the operation of
spin-Hall oscillators.
|
1602.06710v1
|
2016-02-24
|
Oscillating solutions of the Vlasov-Poisson system -- A numerical investigation
|
Numerical evidence is given that spherically symmetric perturbations of
stable spherically symmetric steady states of the gravitational Vlasov-Poisson
system lead to solutions which oscillate in time. The oscillations can be
periodic in time or damped. Along one-parameter families of polytropic steady
states we establish an Eddington-Ritter type relation which relates the period
of the oscillation to the central density of the steady state. The numerically
obtained periods are used to estimate possible periods for typical elliptical
galaxies.
|
1602.07989v1
|
2016-02-26
|
Self-synchronization of Kerr-nonlinear Optical Parametric Oscillators
|
We introduce a new, reduced nonlinear oscillator model governing the
spontaneous creation of sharp pulses in a damped, driven, cubic nonlinear
Schroedinger equation. The reduced model embodies the fundamental connection
between mode synchronization and spatiotemporal pulse formation. We identify
attracting solutions corresponding to stable cavity solitons and Turing
patterns. Viewed in the optical context, our results explain the recently
reported $\pi$ and $\pi/2$ steps in the phase spectrum of microresonator-based
optical frequency combs.
|
1602.08523v1
|
2016-02-27
|
Solitons in an extended nonlinear Schrödinger equation with third-order dispersion and pseudo-Raman effect
|
Dynamics of solitons is considered in an extended nonlinear Schr\"odinger
equation, including a pseudo-stimulated-Raman-scattering (pseudo-SRS) term
(scattering on damping low-frequency waves, third-order dispersion (TOD) and
inhomogeneity of the spatial second-order dispersion (SOD). It is shown that
wave-number downshift by the pseudo-SRS may be compensated by upshift provided
by spatially increasing SOD with taking into account TOD. The equilibrium state
is stable for positive parameter of TOD and unstable for negative one. The
analytical solutions are verified by comparison with numerical results
|
1602.08572v1
|
2016-03-01
|
Classical-field description of the quantum effects in the light-atom interaction
|
In this paper I show that light-atom interaction can be described using
purely classical field theory without any quantization. In particular, atom
excitation by light that accounts for damping due to spontaneous emission is
fully described in the framework of classical field theory. I show that three
well-known laws of the photoelectric effect can also be derived and that all of
its basic properties can be described within classical field theory.
|
1603.02102v2
|
2016-03-12
|
One-way Quantum Deficit and Decoherence for Two-qubit $X$ States
|
We study one-way quantum deficit of two-qubit $X$ states systematically from
analytical derivations. An effective approach to compute one-way quantum
deficit of two-qubit $X$ states has been provided. Analytical results are
presented as for detailed examples. Moreover, we demonstrate the decoherence of
one-way quantum deficit under phase damping channel.
|
1603.03846v1
|
2016-03-16
|
Distributed Inexact Damped Newton Method: Data Partitioning and Load-Balancing
|
In this paper we study inexact dumped Newton method implemented in a
distributed environment. We start with an original DiSCO algorithm
[Communication-Efficient Distributed Optimization of Self-Concordant Empirical
Loss, Yuchen Zhang and Lin Xiao, 2015]. We will show that this algorithm may
not scale well and propose an algorithmic modifications which will lead to less
communications, better load-balancing and more efficient computation. We
perform numerical experiments with an regularized empirical loss minimization
instance described by a 273GB dataset.
|
1603.05191v1
|
2016-03-21
|
The relaxation rate of a stochastic spreading process in a closed ring
|
The relaxation process of a diffusive ring becomes under-damped if the bias
(so called affinity) exceeds a critical threshold value, aka delocalization
transition. This is related to the spectral properties of the pertinent
stochastic kernel. We find the dependence of the relaxation rate on the
affinity and on the length of the ring. Additionally we study the implications
of introducing a weak-link into the circuit, and illuminate some subtleties
that arise while taking the continuum limit of the discrete model.
|
1603.06330v2
|
2016-03-22
|
The weak solution to a Boltzmann type equation and its energy conservation
|
In this paper, we study the initial value problem of a Boltzmann type
equation with a nonlinear degenerate damping. We prove the existence of global
weak solutions with large initial data, in three dimensional space. We rely on
a variant version of the Gronwall inequality and $L^p$ regularity of average
velocities to derive the compactness of solutions to a suitable approximation.
This allows us to recover a weak solution by passing to the limits. After the
existence result, we also prove energy conservation for the weak solution under
some certain condition.
|
1603.06932v2
|
2016-03-22
|
Suppression of phase mixing in drift-kinetic plasma turbulence
|
Transfer of free energy from large to small velocity-space scales by phase
mixing leads to Landau damping in a linear plasma. In a turbulent drift-kinetic
plasma, this transfer is statistically nearly canceled by an inverse transfer
from small to large velocity-space scales due to "anti-phase-mixing" modes
excited by a stochastic form of plasma echo. Fluid moments (density, velocity,
temperature) are thus approximately energetically isolated from the higher
moments of the distribution function, so phase mixing is ineffective as a
dissipation mechanism when the plasma collisionality is small.
|
1603.06968v1
|
2016-04-06
|
Quasinormal modes and Hawking radiation of a Reissner-Nordström black hole surrounded by quintessence
|
We investigate quasinormal modes (QNMs) and Hawking radiation of a
Reissner-Nordstr\"om black hole sur-rounded by quintessence. The
Wentzel-Kramers-Brillouin (WKB) method is used to evaluate the QNMs and the
rate of radiation. The results show that due to the interaction of the
quintessence with the background metric, the QNMs of the black hole damp more
slowly when increasing the density of quintessence and the black hole radiates
at slower rate.
|
1604.02140v1
|
2016-04-08
|
On the Hessian of Shape Matching Energy
|
In this technical report we derive the analytic form of the Hessian matrix
for shape matching energy. Shape matching is a useful technique for meshless
deformation, which can be easily combined with multiple techniques in real-time
dynamics. Nevertheless, it has been rarely applied in scenarios where implicit
integrators are required, and hence strong viscous damping effect, though
popular in simulation systems nowadays, is forbidden for shape matching. The
reason lies in the difficulty to derive the Hessian matrix of the shape
matching energy. Computing the Hessian matrix correctly, and stably, is the key
to more broadly application of shape matching in implicitly-integrated systems.
|
1604.02483v3
|
2016-04-17
|
Small Mass Limit of a Langevin Equation on a Manifold
|
We study damped geodesic motion of a particle of mass $m$ on a Riemannian
manifold, in the presence of an external force and noise. Lifting the resulting
stochastic differential equation to the orthogonal frame bundle, we prove that,
as $m \to 0$, its solutions converge to solutions of a limiting equation which
includes a {\it noise-induced drift} term. A very special case of the main
result presents Brownian motion on the manifold as a limit of inertial systems.
|
1604.04819v2
|
2016-04-19
|
On the viscous Cahn-Hilliard equation with singular potential and inertial term
|
We consider a relaxation of the viscous Cahn-Hilliard equation induced by the
second-order inertial term~$u_{tt}$. The equation also contains a semilinear
term $f(u)$ of "singular" type. Namely, the function $f$ is defined only on a
bounded interval of ${\mathbb R}$ corresponding to the physically admissible
values of the unknown $u$, and diverges as $u$ approaches the extrema of that
interval. In view of its interaction with the inertial term $u_{tt}$, the term
$f(u)$ is difficult to be treated mathematically. Based on an approach
originally devised for the strongly damped wave equation, we propose a suitable
concept of weak solution based on duality methods and prove an existence
result.
|
1604.05539v1
|
2016-04-20
|
A non-relativistic Model of Plasma Physics Containing a Radiation Reaction Term
|
While a fully relativistic collisionless plasma is modeled by the
Vlasov-Maxwell system a good approximation in the non-relativistic limit is
given by the Vlasov-Poisson system. We modify the Vlasov-Poisson system so that
damping due to the relativistic effect of radiation reaction is included. We
prove the existence and uniqueness as well as the higher regularity of local
classical solutions. These theorems also include the higher regularity of
classical solutions of the Vlasov-Poisson system depending on the regularity of
the initial datum.
|
1604.05869v1
|
2016-05-10
|
Fixed-Point Methods on Small-Signal Stability Analysis
|
In this paper we introduce the Diagonal Dominant Pole Spectrum Eigensolver
(DDPSE), which is a fixed-point method that computes several eigenvalues of a
matrix at a time. DDPSE is a slight modification of the Dominant Pole Spectrum
Eigensolver (DPSE), that has being used in power system stability studies. We
show that both methods have local quadratic convergence. Moreover, we present
practical results obtained by both methods, from which we can see that those
methods really compute dominant poles of a transfer function of the type
$c^T(A-sI)^{-1}b$, where $b$ and $c$ are vectors, besides being also effective
in finding low damped modes of a large scale power system.
|
1605.03223v1
|
2016-05-11
|
Super Bloch Oscillation in a PT symmetric system
|
Wannier-Stark ladder in a PT symmetric system is generally complex that leads
to amplified/damped Bloch oscillation. We show that a non-amplified wave packet
oscillation with very large amplitude can be realized in a non-Hermitian tight
binding lattice if certain conditions are satisfied. We show that pseudo PT
symmetry guarantees the reality of the quasi energy spectrum in our system.
|
1605.03517v2
|
2016-05-15
|
Minimum output entropy of a non-Gaussian quantum channel
|
We introduce a model of non-Gaussian quantum channel that stems from the
combination of two physically relevant processes occurring in open quantum
systems, namely amplitude damping and dephasing. For it we find input states
approaching zero output entropy, while respecting the input energy constraint.
These states fully exploit the infinite dimensionality of the Hilbert space.
Upon truncation of the latter, the minimum output entropy remains finite and
optimal input states for such a case are conjectured thanks to numerical
evidences.
|
1605.04525v1
|
2016-05-25
|
Design of nonlinear optical response of multipole-type excitons by film thickness and incident pulse width
|
We theoretically investigate the nonlinear optical pulse responses of
excitons in a thin film where the excitonic center-of-mass motion is confined.
A large interaction volume between excitons and radiation yields particular
coupled states with radiative decay times reaching several femto-seconds. By
considering two polarization directions of light, we reveal that these
fast-decay modes dominantly survive in an optical Kerr spectra even under a
massive nonradiative damping $\Gamma=30$ meV. The results clearly show that
there is an optimal combination of the incident pulse width and the film
thickness for maximizing the integrated intensity of nonlinear signals.
|
1605.07916v2
|
2016-05-26
|
Dynamics of thin liquid films on a porous substrate in zero gravity
|
The long-wave dynamics of liquid films on isothermal substrates show a
dynamic competition between various physical mechanisms. If the destabilizing
effect of thermocapillarity overcomes the stabilizing effect of surface tension
and gravity, the liquid film ruptures in finite time, through the formation of
primary and secondary thermocapillary finger structures.
The long-wave evolution dynamics are compared for two different substrate
types: isothermal non-porous and isothermal porous for small Biot number in a
zero gravity environment. The multi-time-scale dynamics is revealed through
time scales obtained from a method of similarity solutions. It is observed that
with an isothermal porous substrate, in zero gravity, secondary thermocapillary
structures are damped through imbibition and that primary thermocapillary
structures persist for long times without rupture.
|
1605.08173v1
|
2016-05-26
|
Strong coupling optical spectra in dipole-dipole interacting optomechanical Tavis-Cummings models
|
We theoretically investigate the emission spectrum of an optomechanical
Tavis-Cummings model: two dipole-dipole interacting atoms coupled to an
optomechanical cavity (OMC). In particular, we study the influence of
dipole-dipole interaction (DDI) on the single-photon spectrum emitted by this
hybrid system in the presence of a strong atom-cavity as well as strong
optomechanical interaction (hereinafter called the strong-strong coupling). We
also show that our analysis is amenable to inclusion of mechanical losses
(under the weak mechanical damping limit) and single-photon loss through
spontaneous emission from the two-level emitters under a non-local Lindblad
model.
|
1605.08182v1
|
2016-05-31
|
Experimental observation of 1/f noise in quasi-bidimensionnal turbulent flows
|
We report the experimental observation of $1/f^{\alpha}$ noise in
quasi-bidimensionnal turbulence of an electromagnetically forced flow. The
large scale velocity $U_L$ exhibits this power-law spectrum with $\alpha \simeq
0.7$ over a range of frequencies smaller than both the characteristic turn-over
frequency and the damping rate of the flow. By studying the statistical
properties of sojourn time in each polarity of $U_L$, we demonstrate that the
$1/f^{\alpha}$ noise is generated by a renewal process, defined by a two-state
model given by the polarities of the large scale circulation. The statistical
properties of this renewal process are shown to control the value of the
exponent $\alpha$.
|
1605.09664v1
|
2016-06-01
|
Measurement-Based Linear Optics
|
A major challenge in optical quantum processing is implementing large, stable
interferometers. Here we propose a virtual, measurement-based interferometer
that is programmed on the fly solely by the choice of homodyne measurement
angles. The effects of finite squeezing are captured as uniform amplitude
damping. We compare our proposal to existing (physical) interferometers and
consider its performance for BosonSampling, which could demonstrate
post-classical computational power in the near future. We prove its efficiency
in time and squeezing (energy) in this setting.
|
1606.00446v2
|
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