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2006-03-10 | Numerical Approach to Multi Dimensional Phase Transitions | We present an algorithm to analyze numerically the bounce solution of
first-order phase transitions. Our approach is well suited to treat phase
transitions with several fields. The algorithm consists of two parts. In the
first part the bounce solution without damping is determined, in which case
energy is conserved. In the second part the continuation to the physically
relevant case with damping is performed. The presented approach is numerically
stable and easily implemented. | 0603081v2 |
1994-06-22 | Damped quantum harmonic oscillator: density operator and related quantities | A closed expression for the density operator of the damped harmonic
oscillator is extracted from the master equation based on the Lindblad theory
for open quantum systems. The entropy and effective temperature of the system
are subsequently calculated and their temporal behaviour is surveyed by showing
how these quantities relax to their equilibrium values. The entropy for a state
characterized by a Wigner distribution function which is Gaussian in form is
found to depend only on the variance of the distribution function. | 9406142v1 |
1997-05-09 | Radiation Damping of a BPS Monopole; an Implication to S-duality | The radiation reaction of a BPS monopole in the presence of incident
electromagnetic waves as well as massless Higgs waves is analyzed classically.
The reactive forces are compared to those of $W$ boson that is interpreted as a
dual partner of the BPS monopole. It is shown that the damping of acceleration
is dual to each other, while in the case of finite size effects the duality is
broken explicitly. Their implications on the duality are discussed. | 9705059v2 |
1997-07-02 | The Asymptotic Method Developed from Weak Turbulent Theory and the Nonlinear Permeability and Damping Rate in QGP | With asymptotic method developed from weak turbulent theory, the kinetic
equations for QGP are expanded in fluctuation field potential $A^T_\mu $.
Considering the second-order and third-order currents, we derive the nonlinear
permeability tensor function from Yang-Mills field equation, and find that the
third-order current is more important in turbulent theory. The nonlinear
permeability formulae for longitudinal color oscillations show that the
non-Abelian effects are more important than the Abelian-like effects. To
compare with other works, we give the numerical result of the damping rate for
the modes with zero wave vector. | 9707052v1 |
2005-04-07 | Continuous area spectrum in regular black hole | We investigate highly damped quasinormal modes of regular black hole coupled
to nonlinear electrodynamics. Using the WKB approximation combined with
complex-integration technique, we show that the real part of the frequency
disappears in the highly damped limit. If we use the Bohr's correspondence
principle, the area spectrum of this black hole is continuous. We discuss its
implication in the loop quantum gravity. | 0504059v2 |
2005-05-16 | Supersymmetrization of the Radiation Damping | We construct a supersymmetrized version of the model to the radiation damping
\cite{03} introduced by the present authors \cite{ACWF}. We dicuss its
symmetries and the corresponding conserved Noether charges. It is shown this
supersymmetric version provides a supersymmetric generalization of the Galilei
algebra obtained in \cite{ACWF}. We have shown that the supersymmetric action
can be splited into dynamically independent external and internal sectors. | 0505142v1 |
1999-08-16 | Topological Entropy and epsilon-Entropy for Damped Hyperbolic Equations | We study damped hyperbolic equations on the infinite line. We show that on
the global attracting set $G$ the $\epsilon$-entropy (per unit length) exists
in the topology of $W^{1,\infty}$. We also show that the topological entropy
per unit length of $G$ exists. These results are shown using two main
techniques: Bounds in bounded domains in position space and for large momenta,
and a novel submultiplicativity argument in $W^{1,\infty}$. | 9908080v1 |
2003-11-28 | Uniform stability of damped nonlinear vibrations of an elastic string | Here we are concerned about uniform stability of damped nonlinear transverse
vibrations of an elastic string fixed at its two ends. The vibrations governed
by nonlinear integro-differential equation of Kirchoff type, is shown to
possess energy uniformly bounded by exponentially decaying function of time.
The result is achieved by considering an energy-like Lyapunov functional for
the system. | 0311527v1 |
2005-07-06 | On stability and stabilization of elastic systems by time-variant feedback | We study a class of elastic systems described by a (hyperbolic) partial
differential equation. Our working example is the equation of a vibrating
string subject to linear disturbance. The main goal is to establish conditions
for stabilization and asymptotic stabilization by applying a fast oscillating
control to the string. In the first situation studied we assume that system is
subject to a damping force; next we consider the system without damping. We
extend the tools of high-order averaging and of chronological calculus for
studying stability of this distributed parameter system. | 0507123v1 |
2006-01-13 | Attractors for damped hyperbolic equations on arbitrary unbounded domains | We prove existence of global attractors for damped hyperbolic equations of
the form $$\aligned \eps u_{tt}+\alpha(x) u_t+\beta(x)u- \sum_{ij}(a_{ij}(x)
u_{x_j})_{x_i}&=f(x,u),\quad x\in \Omega, t\in[0,\infty[, u(x,t)&=0,\quad x\in
\partial \Omega, t\in[,\infty[.\endaligned$$ on an unbounded domain $\Omega$,
without smoothness assumptions on $\beta(\cdot)$, $a_{ij}(\cdot)$, $f(\cdot,u)$
and $\partial\Omega$, and $f(x,\cdot)$ having critical or subcritical growth. | 0601319v3 |
2007-03-09 | Analyticity and Riesz basis property of semigroups associated to damped vibrations | Second order equations of the form $z'' + A_0 z + D z'=0$ in an abstract
Hilbert space are considered. Such equations are often used as a model for
transverse motions of thin beams in the presence of damping. We derive various
properties of the operator matrix $A$ associated with the second order problem
above. We develop sufficient conditions for analyticity of the associated
semigroup and for the existence of a Riesz basis consisting of eigenvectors and
associated vectors of $A$ in the phase space. | 0703247v1 |
2007-03-21 | Existence and asymptotic behavior of $C^1$ solutions to the multidimensional compressible Euler equations with damping | In this paper, the existence and asymptotic behavior of $C^1$ solutions to
the multidimensional compressible Euler equations with damping on the framework
of Besov space are considered. We weaken the regularity requirement of the
initial data, and improve the well-posedness results of Sideris-Thomases-Wang
(Comm.P.D.E. 28 (2003) 953). The global existence lies on a crucial a-priori
estimate which is proved by the spectral localization method. The main analytic
tools are the Littlewood-Paley decomposition and Bony's para-product formula. | 0703621v1 |
2000-12-22 | The Vlasov-Poisson system with radiation damping | We set up and analyze a model of radiation damping within the framework of
continuum mechanics, inspired by a model of post-Newtonian hydrodynamics due to
Blanchet, Damour and Schaefer. In order to simplify the problem as much as
possible we replace the gravitational field by the electromagnetic field and
the fluid by kinetic theory. We prove that the resulting system has a
well-posed Cauchy problem globally in time for general initial data and in all
solutions the fields decay to zero at late times. In particular, this means
that the model is free from the runaway solutions which frequently occur in
descriptions of radiation reaction. | 0012041v1 |
2003-01-17 | Quantum mechanics of damped systems | We show that the quantization of a simple damped system leads to a
self-adjoint Hamiltonian with a family of complex generalized eigenvalues. It
turns out that they correspond to the poles of energy eigenvectors when
continued to the complex energy plane. Therefore, the corresponding generalized
eigenvectors may be interpreted as resonant states. We show that resonant
states are responsible for the irreversible quantum dynamics of our simple
model. | 0301024v3 |
2003-07-23 | Quantum Mechanics of Damped Systems II. Damping and Parabolic Potential Barrier | We investigate the resonant states for the parabolic potential barrier known
also as inverted or reversed oscillator. They correspond to the poles of
meromorphic continuation of the resolvent operator to the complex energy plane.
As a byproduct we establish an interesting relation between parabolic cylinder
functions (representing energy eigenfunctions of our system) and a class of
Gel'fand distributions used in our recent paper. | 0307047v1 |
2001-07-02 | Pattern formation and localization in the forced-damped FPU lattice | We study spatial pattern formation and energy localization in the dynamics of
an anharmonic chain with quadratic and quartic intersite potential subject to
an optical, sinusoidally oscillating field and a weak damping. The
zone-boundary mode is stable and locked to the driving field below a critical
forcing that we determine analytically using an approximate model which
describes mode interactions. Above such a forcing, a standing modulated wave
forms for driving frequencies below the band-edge, while a ``multibreather''
state develops at higher frequencies. Of the former, we give an explicit
approximate analytical expression which compares well with numerical data. At
higher forcing space-time chaotic patterns are observed. | 0107002v1 |
2003-06-16 | On the influence of noise on chaos in nearly Hamiltonian systems | The simultaneous influence of small damping and white noise on Hamiltonian
systems with chaotic motion is studied on the model of periodically kicked
rotor. In the region of parameters where damping alone turns the motion into
regular, the level of noise that can restore the chaos is studied. This
restoration is created by two mechanisms: by fluctuation induced transfer of
the phase trajectory to domains of local instability, that can be described by
the averaging of the local instability index, and by destabilization of motion
within the islands of stability by fluctuation induced parametric modulation of
the stability matrix, that can be described by the methods developed in the
theory of Anderson localization in one-dimensional systems. | 0306024v1 |
2003-07-30 | Faraday Wave Pattern Selection Via Multi-Frequency Forcing | We use symmetry considerations to investigate how damped modes affect pattern
selection in multi-frequency forced Faraday waves. We classify and tabulate the
most important damped modes and determine how the corresponding resonant triad
interactions depend on the forcing parameters. The relative phase of the
forcing terms may be used to enhance or suppress the nonlinear interactions. We
compare our predictions with numerical results and discuss their implications
for recent experiments. Our results suggest how to design multi-frequency
forcing functions that favor chosen patterns in the lab. | 0307056v1 |
2004-10-11 | Nodal two-dimensional solitons in nonlinear parametric resonance | The parametrically driven damped nonlinear Schr\"odinger equation serves as
an amplitude equation for a variety of resonantly forced oscillatory systems on
the plane. In this note, we consider its nodal soliton solutions. We show that
although the nodal solitons are stable against radially-symmetric perturbations
for sufficiently large damping coefficients, they are always unstable to
azimuthal perturbations. The corresponding break-up scenarios are studied using
direct numerical simulations. Typically, the nodal solutions break into
symmetric "necklaces" of stable nodeless solitons. | 0410012v1 |
2004-10-21 | Stabilization mechanism for two-dimensional solitons in nonlinear parametric resonance | We consider a simple model system supporting stable solitons in two
dimensions. The system is the parametrically driven damped nonlinear
Schr\"odinger equation, and the soliton stabilises for sufficiently strong
damping. The purpose of this note is to elucidate the stabilisation mechanism;
we do this by reducing the partial differential equation to a
finite-dimensional dynamical system. Our conclusion is that the negative
feedback loop occurs via the enslaving of the soliton's phase, locked to the
driver, to its amplitude and width. | 0410044v1 |
2006-01-14 | Vibration of the Duffing Oscillator: Effect of Fractional Damping | We have applied the Melnikov criterion to examine a global homoclinic
bifurcation and transition to chaos in a case of the Duffing system with
nonlinear fractional damping and external excitation.
Using perturbation methods we have found a critical forcing amplitude above
which the system may behave chaotically.
The results have been verified by numerical simulations using standard
nonlinear tools as
Poincare maps and a Lyapunov exponent. Above the critical Melnikov amplitude
$\mu_c$, which is the sufficient condition of a global homoclinic bifurcation,
we have observed the region with a transient chaotic motion. | 0601033v1 |
2006-10-22 | Response of a Magneto-Rheological Fluid Damper Subjected to Periodic Forcing in a High Frequency Limit | We explored vibrations of a single-degree of freedom oscillator with a
magneto-rheological damper subjected to kinematic excitations. Using fast and
slow scales decoupling procedure we derived an effective damping coefficient in
the limit of high frequency excitation. Damping characteristics, as functions
of velocity, change considerably especially by terminating the singular
non-smoothness points. This effect was more transparent for a larger control
parameter which was defined as the product of the excitation amplitude and its
frequency. | 0610055v1 |
2006-11-02 | Solitons in strongly driven discrete nonlinear Schrödinger-type models | Discrete solitons in the Ablowitz-Ladik (AL) and discrete nonlinear
Schr\"odinger (DNLS) equations with damping and strong rapid drive are
investigated. The averaged equations have the forms of the parametric AL and
DNLS equations. A new type of parametric bright discrete soliton and cnoidal
waves are found and the stability properties are analyzed. The analytical
predictions of the perturbed inverse scattering transform are confirmed by the
numerical simulations of the AL and DNLS equations with rapidly varying drive
and damping. | 0611004v1 |
1992-12-14 | Microscopic Origin of Quantum Chaos in Rotational Damping | The rotational spectrum of $^{168}$Yb is calculated diagonalizing different
effective interactions within the basis of unperturbed rotational bands
provided by the cranked shell model. A transition between order and chaos
taking place in the energy region between 1 and 2 MeV above the yrast line is
observed, associated with the onset of rotational damping. It can be related to
the higher multipole components of the force acting among the unperturbed
rotational bands. | 9212005v1 |
1996-12-17 | Damping mechanisms of the Delta resonance in nuclei | The damping mechanisms of the Delta(1232) resonance in nuclei are studied by
analyzing the quasi-free decay reactions 12C(pi+,pi+ p)11B and 12C(3He,t pi+
p)11B and the 2p emission reactions 12C(pi+,pp)10B and 12C(3He,t pp)10B. The
coincidence cross sections are calculated within the framework of the
isobar-hole model. It is found that the 2p emission process induced by the
decay of the Delta resonance in the nucleus can be consistently described by a
pi+rho+g' model for the Delta+N -> N+N decay interaction. | 9612046v1 |
1997-11-08 | Cooperative damping mechanism of the resonance in the nuclear photoabsorption | We propose a resonance damping mechanism to explain the disappearance of the
peaks around the position of the resonances higher than the $\Delta$ resonance
in the nuclear photoabsorption. This phenomenon is understood by taking into
account the cooperative effect of the collision broadening of $\Delta$ and
$N^{*}$, the pion distortion and the interference in the two-pion
photoproduction processes in the nuclear medium. | 9711017v4 |
1998-05-27 | Collisional Damping of Nuclear Collective Vibrations in a Non-Markovian Transport Approach | A detailed derivation of the collisional widths of collective vibrations is
presented in both quantal and semi-classical frameworks by considering the
linearized limits of the extended TDHF and the BUU model with a non-Markovian
binary collision term. Damping widths of giant dipole and giant quadrupole
excitations are calculated by employing an effective Skyrme force, and the
results are compared with GDR measurements in Lead and Tin nuclei at finite
temperature. | 9805050v1 |
1999-07-06 | Probing the width of compound states with rotational gamma rays | The intrinsic width of (multiparticle-multihole) compound states is an
elusive quantity, of difficult direct access, as it is masked by damping
mechanisms which control the collective response of nuclei. Through microscopic
cranked shell model calculations, it is found that the strength function
associated with two-dimensional gamma-coincidence spectra arising from
rotational transitions between states lying at energies >1 MeV above the yrast
line, exhibits a two-component structure controlled by the rotational (wide
component) and compound (narrow component) damping width. This last component
is found to be directly related to the width of the multiparticle-multihole
autocorrelation function. | 9907016v1 |
1999-07-09 | Color plasma oscillation in strangelets | The dispersion relation and damping rate of longitudinal color plasmons in
finite strange quark matter (strangelets) are evaluated in the limits of weak
coupling, low temperature, and long wavelength. The property of the QCD vacuum
surrounding a strangelet makes the frequency of the plasmons nearly the same as
the color plasma frequency of bulk matter. The plasmons are damped by their
coupling with individual excitations of particle-hole pairs of quarks, of which
the energy levels are discretized by the boundary. For strangelets of
macroscopic size, the lifetime of the plasmons is found to be proportional to
the size, as in the case of the usual plasma oscillations in metal
nanoparticles. | 9907039v1 |
1999-09-21 | On the Collisional Damping of Giant Dipole Resonance | Collisional damping widths of giant dipole excitations are calculated in
Thomas-Fermi approximation by employing the microscopic in-medium
cross-sections of Li and Machleidt and the phenomenological Gogny force. The
results obtained in both calculations compare well, but account for about
25-35% of the observed widths in $^{120}Sn$ and $^{208}Pb$ at finite
temperatures. | 9909057v1 |
2000-01-09 | Strongly damped nuclear collisions: zero or first sound ? | The relaxation of the collective quadrupole motion in the initial stage of a
central heavy ion collision at beam energies $E_{lab}=5\div20$ AMeV is studied
within a microscopic kinetic transport model. The damping rate is shown to be a
non-monotonic function of E_{lab} for a given pair of colliding nuclei. This
fact is interpreted as a manifestation of the zero-to-first sound transition in
a finite nuclear system. | 0001016v1 |
2002-11-18 | Collision damping in the pi 3He -> d'N reaction near the threshold | We present a simple quantum mechanical model exploiting the optical potential
approach for the description of collision damping in the reaction pi 3He -> d'N
near the threshold, which recently has been measured at TRIUMF. The influence
of the open d'N -> NNN channel is taken into account. It leads to a suppression
factor of about ten in the d' survival probability. Applications of the method
to other reactions are outlined. | 0211050v1 |
2003-03-14 | Pion damping width from SU(2) x SU(2) NJL model | Within the framework of the NJL model, we investigate the modification of the
pion damping width in a hot pion gas for temperatures ranging from 0 to 180
MeV. The pion is found to broaden noticeably at T > 60 MeV. Near the chiral
phase transition T ~ 180 MeV, the pion width is saturated and amounts to 70
MeV. The main contribution to the width comes from pion-pion collisions. Other
contributions are found negligibly small. | 0303034v1 |
2004-06-09 | Damped collective motion of isolated many body systems within a variational approach to functional integrals | Two improvements with respect to previous formulations are presented for the
calculation of the partition function $\mathcal{Z}$ of small, isolated and
interacting many body systems. By including anharmonicities and employing a
variational approach quantum effects can be treated even at very low
temperatures. A method is proposed of how to include collisional damping.
Finally, our approach is applied to the calculation of the decay rate of
metastable systems. | 0406025v1 |
2004-07-26 | Damped collective motion of many body systems: A variational approach to the quantal decay rate | We address the problem of collective motion across a barrier like encountered
in fission. A formula for the quantal decay rate is derived which bases on a
recently developed variational approach for functional integrals. This formula
can be applied to low temperatures that have not been accessible within the
former PSPA type approach. To account for damping of collective motion one
particle Green functions are dressed with appropriate self-energies. | 0407092v2 |
1997-11-15 | Fluctuational phase-flip transitions in parametrically pumped oscillators | We analyze the rates of noise-induced transitions between period-two
attractors. The model investigated is an underdamped oscillator parametrically
driven by a field at nearly twice the oscillator eigenfrequency. The activation
energy of the transitions is analyzed as a function of the frequency detuning
and field amplitude scaled by the damping and nonlinearity parameters of the
oscillator. The parameter ranges where the system is bi- and tristable are
investigated. Explicit results are obtained in the limit of small damping (or
strong driving), and near bifurcation points. | 9711014v1 |
1999-05-31 | Collisionless Damping of Low-Frequency Magnetosonic Pulses in a Two-Ion-Species Plasma | Low-frequency mangnetosonic pulses in a two-ion-species plasma are studied
theoretically and by simulation with a one-dimensional electromagnetic
simulation code based on a three-fluid model, with particular attention to the
dynamics of minority heavy ions. It is found that heavy ions can gain some
energy from the pulses. Because of this energy transfer, the pulses are damped
even if the plasma is collisionless and pulse propagation is perpendicular to
the magnetic field. | 9905059v1 |
2000-10-17 | Bunch Length Measurements at the ATF Damping Ring in April 2000 | This report presents bunch length and energy spread measurements performed in
April 2000 at the ATF Damping Ring, at KEK. Measurements were performed with
the beam on and then off the linear (difference) coupling resonance. Due to
strong intra-beam scattering in the ATF ring, the results depended strongly on
the coupling. | 0010043v1 |
2000-12-21 | Phase transition in the collisionless regime for wave-particle interaction | Gibbs statistical mechanics is derived for the Hamiltonian system coupling
self-consistently a wave to N particles. This identifies Landau damping with a
regime where a second order phase transition occurs. For nonequilibrium initial
data with warm particles, a critical initial wave intensity is found: above it,
thermodynamics predicts a finite wave amplitude in the limit of infinite N;
below it, the equilibrium amplitude vanishes. Simulations support these
predictions providing new insight on the long-time nonlinear fate of the wave
due to Landau damping in plasmas. | 0012053v1 |
2001-09-25 | Creep and Mechanical Oscillator Damping | Although "friction" is included in many models of oscillator damping,
including viscous ones applied to the pendulum; they "miss the mark" with
regard to a conceptual understanding of the mechanisms responsible for energy
loss. The theory of the present paper corrects some of these misunderstandings
by considering the influence of internal friction which derives from the
structural members of the oscillator through secondary rather than primary
creep. The simple model properly describes the variation of Q with frequency. | 0109067v1 |
2001-11-06 | Electromagnetic induction and damping - quantitative experiments using PC interface | A bar magnet, attached to an oscillating system, passes through a coil
periodically, generating a series of emf pulses. A novel method is described
for the quantitative verification of Faraday's law which eliminates all errors
associated with angular measurements, thereby revealing delicate features of
the underlying mechanics. When electromagnetic damping is activated by
short-circuiting the coil, a distinctly linear decay of oscillation amplitude
is surprisingly observed. A quantitative analysis reveals an interesting
interplay of the electromagnetic and mechanical time scales. | 0111016v1 |
2003-08-31 | Effects of Bulk Viscosity in Non-linear Bubble Dynamics | The non-linear bubble dynamics equations in a compressible liquid have been
modified considering the effects of compressibility of both the liquid and the
gas at the bubble interface. A new bubble boundary equation has been derived,
which includes a new term resulted from the liquid bulk viscosity effects. The
influence of this term has been numerically investigated considering the
effects of water vapor and chemical reactions on the bubble evolution. The
results clearly indicate that the new term has an important damping role at the
collapse, so that its consideration decreases the amplitude of the bubble
rebounds after the collapse. This damping feature is more remarkable for higher
deriving pressures. | 0309012v1 |
2004-04-30 | On violation of the Robinson's damping criterion and enhanced cooling of ion, electron and muon beams in storage rings | Limits of applicability of the Robinson's damping criterion and the problem
of enhanced cooling of particle beams in storage rings beyond the criterion are
discussed. | 0404142v6 |
2004-12-28 | Electron Bernstein waves in spherical tokamak plasmas with "magnetic wells" | In addition to traditional regimes with monotonously increasing magnetic
field, regimes with "magnetic wells" also occur in spherical tokamaks (STs).
The magnetic field profile inversion modifies significantly the whole picture
of the wave propagation and damping. Since the magnetic wells may become quite
common with further improvement of ST performance, analysis of such
configurations is of interest for assessment of EBW plasma heating an CD
perspectives. In this paper the basic features of the EBWs propagation and
damping for the second cyclotron harmonic in a slab model are considered. | 0412173v1 |
2005-08-16 | Creep-Enhanced Low-Frequency Sensitivity of Seismometers | The frequency response of a seismometer is typically assumed to be the
textbook case of a viscous damped, simple harmonic oscillator. Real mechanical
oscillators are not ideal, and the damping at low frequencies, due to internal
friction, is presently too poorly understood to describe from first principles.
Even if the low-level motions were smooth (which they are not), the mean
position of a seismic mass changes because of creep and creep recovery. This
article shows that secondary creep can actually serve to increase the
sensitivity of a seismometer at low frequencies. | 0508105v1 |
2006-06-22 | Looking for a time independent Hamiltonian of a dynamical system | In this paper we introduce a method for finding a time independent
Hamiltonian of a given dynamical system by canonoid transformation. We also
find a condition that the system should satisfy to have an equivalent time
independent formulation. We study the example of damped oscillator and give the
new time independent Hamiltonian for it, which has the property of tending to
the standard Hamiltonian of the harmonic oscillator as damping goes to zero. | 0606197v2 |
1996-02-27 | Effects of Loss and Decoherence on a Simple Quantum Computer | We investigate the impact of loss (amplitude damping) and decoherence (phase
damping) on the performance of a simple quantum computer which solves the
one-bit Deutsch problem. The components of this machine are beamsplitters and
nonlinear optical Kerr cells, but errors primarily originate from the latter.
We develop models to describe the effect of these errors on a quantum optical
Fredkin gate. The results are used to analyze possible error correction
strategies in a complete quantum computer. We find that errors due to loss can
be avoided perfectly by appropriate design techniques, while decoherence can be
partially dealt with using projective error correction. | 9602018v1 |
1996-11-25 | The Quantum state diffusion model and the driven damped nonlinear oscillator | We consider a driven damped anharmonic oscillator which classically leads to
a bistable steady state and to hysteresis. The quantum counterpart for this
system has an exact analytical solution in the steady state which does not
display any bistability or hysteresis. We use quantum state diffusion theory to
describe this system and to provide a new perspective on the lack of hysteresis
in the quantum regime so as to study in detail the quantum to classical
transition. The analysis is also relevant to measurements of a single
periodically driven electron in a Penning trap where hysteresis has been
observed. | 9611044v1 |
1997-12-02 | Prevention of dissipation with two particles | An error prevention procedure based on two-particle encoding is proposed for
protecting an arbitrary unknown quantum state from dissipation, such as phase
damping and amplitude damping. The schemes, which exhibits manifestation of the
quantum Zeno effect, is effective whether quantum bits are decohered
independently or cooperatively. We derive the working condition of the scheme
and argue that this procedure has feasible practical implementation. | 9712005v1 |
1998-02-23 | Caldirola-Kanai Oscillator in Classical Formulation of Quantum Mechanics | The quadrature distribution for the quantum damped oscillator is introduced
in the framework of the formulation of quantum mechanics based on the
tomography scheme. The probability distribution for the coherent and Fock
states of the damped oscillator is expressed explicitly in terms of Gaussian
and Hermite polynomials, correspondingly. | 9802057v1 |
1999-03-22 | Decoherence - Fluctuation Relation and Measurement Noise | We discuss fluctuations in the measurement process and how these fluctuations
are related to the dissipational parameter characterising quantum damping or
decoherence. On the example of the measuring current of the variable-barrier or
QPC problem we show there is an extra noise or fluctuation connected with the
possible different outcomes of a measurement. This noise has an enhanced short
time component which could be interpreted as due to ``telegraph noise'' or
``wavefunction collapses''. Furthermore the parameter giving the the strength
of this noise is related to the parameter giving the rate of damping or
decoherence. | 9903072v1 |
1999-07-27 | Nonclassical correlations in damped N-solitons | The quantum statistics of damped higher-order optical solitons are analyzed
numerically, using cumulant-expansion techniques in Gaussian approximation. A
detailed analysis of nonclassical properties in both the time and the frequency
domain is given, with special emphasis on the role of absorption. Highly
nonclassical broadband spectral correlation is predicted. | 9907090v2 |
2001-01-08 | Cavity-damping-induced transitions in a driven atom-cavity system | We investigate the fluorescence spectrum of a two-level atom in a cavity when
the atom is driven by a classical field. We show that forbidden dipole
transitions in the Jaynes-Cummings Ladder structure are induced in the presence
of the cavity damping, which deteriorates the degree of otherwise perfect
destructive interference among the transition channels. With the larger cavity
decay, these transitions are more enhanced. | 0101036v1 |
2001-06-09 | Squeezing enhancement by damping in a driven atom-cavity system | In a driven atom-cavity coupled system in which the two-level atom is driven
by a classical field, the cavity mode which should be in a coherent state in
the absence of its reservoir, can be squeezed by coupling to its reservoir. The
squeezing effect is enhanced as the damping rate of the cavity is increased to
some extent. | 0106054v1 |
2001-08-01 | Decoherence-induced wave packet splitting | We provide an intuitive interpretation of the optical Stern-Gerlach effect
(OSGE) in the dressed-state point of view. We also analyze the effect of atomic
damping in an experiment on the OSGE. We show that the atomic damping also
causes the wave packet splitting, in a non-mechanical fashion, as opposed to
the coherent process that is mechanical. | 0108005v1 |
2001-08-11 | A Canonical Approach to the Quantization of the Damped Harmonic Oscillator | We provide a new canonical approach for studying the quantum mechanical
damped harmonic oscillator based on the doubling of degrees of freedom
approach. Explicit expressions for Lagrangians of the elementary modes of the
problem, characterising both forward and backward time propagations are given.
A Hamiltonian analysis, showing the equivalence with the Lagrangian approach,
is also done. Based on this Hamiltonian analysis, the quantization of the model
is discussed. | 0108055v2 |
2002-05-09 | Implementation of quantum maps by programmable quantum processors | A quantum processor is a device with a data register and a program register.
The input to the program register determines the operation, which is a
completely positive linear map, that will be performed on the state in the data
register. We develop a mathematical description for these devices, and apply it
to several different examples of processors. The problem of finding a processor
that will be able to implement a given set of mappings is also examined, and it
is shown that while it is possible to design a finite processor to realize the
phase-damping channel, it is not possible to do so for the amplitude-damping
channel. | 0205050v1 |
2002-08-28 | Damped Quantum Interference using Stochastic Calculus | It is shown how the phase-damping master equation, either in Markovian and
nonMarkovian regimes, can be obtained as an averaged random unitary evolution.
This, apart from offering a common mathematical setup for both regimes, enables
us to solve this equation in a straightforward manner just by solving the
Schrodinger equation and taking the stochastic expectation value of its
solutions after an adequate modification. Using the linear entropy as a figure
of merit (basically the loss of quantum coherence) the distinction of four
kinds of environments is suggested. | 0208176v1 |
2002-10-31 | Quantum Markov Channels for Qubits | We examine stochastic maps in the context of quantum optics. Making use of
the master equation, the damping basis, and the Bloch picture we calculate a
non-unital, completely positive, trace-preserving map with unequal damping
eigenvalues. This results in what we call the squeezed vacuum channel. A
geometrical picture of the effect of stochastic noise on the set of pure state
qubit density operators is provided. Finally, we study the capacity of the
squeezed vacuum channel to transmit quantum information and to distribute EPR
states. | 0211001v1 |
2003-01-17 | Concurrence and foliations induced by some 1-qubit channels | We start with a short introduction to the roof concept. An elementary
discussion of phase-damping channels shows the role of anti-linear operators in
representing their concurrence. A general expression for some concurrences is
derived. We apply it to 1-qubit channels of length two, getting induced
foliations of the state space, the optimal decompositions, and the entropy of a
state with respect to these channels. For amplitude-damping channels one
obtains an expression for the Holevo capacity allowing for easy numerical
calculations. | 0301088v1 |
2003-05-19 | Statistical Effects in the Multistream Model for Quantum Plasmas | A statistical multistream description of quantum plasmas is formulated, using
the Wigner-Poisson system as dynamical equations. A linear stability analysis
of this system is carried out, and it is shown that a Landau-like damping of
plane wave perturbations occurs due to the broadening of the background Wigner
function that arises as a consequence of statistical variations of the wave
function phase. The Landau-like damping is shown to suppress instabilities of
the one- and two-stream type. | 0305102v1 |
2003-06-28 | Misbelief and misunderstandings on the non--Markovian dynamics of a damped harmonic oscillator | We use the exact solution for the damped harmonic oscillator to discuss some
relevant aspects of its open dynamics often mislead or misunderstood. We
compare two different approximations both referred to as Rotating Wave
Approximation. Using a specific example, we clarify some issues related to
non--Markovian dynamics, non--Lindblad type dynamics, and positivity of the
density matrix. | 0306193v3 |
2003-11-26 | Effective damping in the Raman cooling of trapped ions | We present a method of treating the interaction of a single three-level ion
with two laser beams. The idea is to apply a unitary transformation such that
the exact transformed Hamiltonian has one of the three levels decoupled for all
values of the detunings. When one takes into account damping, the evolution of
the system is governed by a master equation usually obtained via adiabatic
approximation under the assumption of far-detuned lasers. To go around the
drawbacks of this technique, we use the same unitary transformation to get an
effective master equation. | 0311183v1 |
2004-06-20 | Entanglement-assisted classical information capacity of the amplitude damping channel | In this paper, we calculate the entanglement-assisted classical information
capacity of amplitude damping channel and compare it with the particular mutual
information which is considered as the entanglement-assisted classical
information capacity of this channel in Ref. 6. It is shown that the difference
between them is very small. In addition, we point out that using partial
symmetry and concavity of mutual information derived from dense coding scheme
one can simplify the calculation of entanglement-assisted classical information
capacities for non-unitary-covariant quantum noisy channels. | 0406140v1 |
2004-08-13 | Decoherence versus Dynamical Casimir Effect | By means of two simple examples: phase and amplitude damping, the impact of
decoherence on the dynamical Casimir effect is investigated. Even without
dissipating energy (i.e., pure phase damping), the amount of created particles
can be diminished significantly via the coupling to the environment (reservoir
theory) inducing decoherence. For a simple microscopic model, it is
demonstrated that spontaneous decays within the medium generate those problems
-- Rabi oscillations are far more advantageous in that respect. These findings
are particularly relevant in view of a recently proposed experimental
verification of the dynamical Casimir effect. PACS: 42.50.Lc, 03.65.Yz,
03.70.+k, 42.50.Dv. | 0408087v2 |
2004-10-11 | Quantizing the damped harmonic oscillator | We consider the Fermi quantization of the classical damped harmonic
oscillator (dho). In past work on the subject, authors double the phase space
of the dho in order to close the system at each moment in time. For an
infinite-dimensional phase space, this method requires one to construct a
representation of the CAR algebra for each time. We show that unitary dilation
of the contraction semigroup governing the dynamics of the system is a logical
extension of the doubling procedure, and it allows one to avoid the
mathematical difficulties encountered with the previous method. | 0410078v1 |
2004-11-18 | Drastic effects of damping mechanisms on the third-order optical nonlinearity | We have investigated the optical response of superradiant atoms, which
undergoes three different damping mechanisms: radiative dissipation
($\gamma_r$), dephasing ($\gamma_d$), and nonradiative dissipation
($\gamma_n$). Whereas the roles of $\gamma_d$ and $\gamma_n$ are equivalent in
the linear susceptibility, the third-order nonlinear susceptibility drastically
depends on the ratio of $\gamma_d$ and $\gamma_n$: When $\gamma_d \ll
\gamma_n$, the third-order susceptibility is essentially that of a single atom.
Contrarily, in the opposite case of $\gamma_d \gg \gamma_n$, the third-order
susceptibility suffers the size-enhancement effect and becomes proportional to
the system size. | 0411129v1 |
2005-01-19 | Stabilizing an atom laser using spatially selective pumping and feedback | We perform a comprehensive study of stability of a pumped atom laser in the
presence of pumping, damping and outcoupling. We also introduce a realistic
feedback scheme to improve stability by extracting energy from the condensate
and determine its effectiveness. We find that while the feedback scheme is
highly efficient in reducing condensate fluctuations, it usually does not alter
the stability class of a particular set of pumping, damping and outcoupling
parameters. | 0501101v1 |
2005-06-11 | Quantum damped oscillator II: Bateman's Hamiltonian vs. 2D Parabolic Potential Barrier | We show that quantum Bateman's system which arises in the quantization of a
damped harmonic oscillator is equivalent to a quantum problem with 2D parabolic
potential barrier known also as 2D inverted isotropic oscillator. It turns out
that this system displays the family of complex eigenvalues corresponding to
the poles of analytical continuation of the resolvent operator to the complex
energy plane. It is shown that this representation is more suitable than the
hyperbolic one used recently by Blasone and Jizba. | 0506091v1 |
2005-06-27 | Entanglement of pair cat states and teleportation | The entanglement of pair cat states in the phase damping channel is studied
by employing the relative entropy of entanglement. It is shown that the pair
cat states can always be distillable in the phase damping channel. Furthermore,
we analyze the fidelity of teleportation for the pair cat states by using joint
measurements of the photon-number sum and phase difference. | 0506217v1 |
2005-07-21 | Entanglement versus mixedness for coupled qubits under a phase damping channel | Quantification of entanglement against mixing is given for a system of
coupled qubits under a phase damping channel. A family of pure initial joint
states is defined, ranging from pure separable states to maximally entangled
state. An ordering of entanglement measures is given for well defined initial
state amount of entanglement. | 0507212v2 |
2005-10-20 | Overdamping by weakly coupled environments | A quantum system weakly interacting with a fast environment usually undergoes
a relaxation with complex frequencies whose imaginary parts are damping rates
quadratic in the coupling to the environment, in accord with Fermi's ``Golden
Rule''. We show for various models (spin damped by harmonic-oscillator or
random-matrix baths, quantum diffusion, quantum Brownian motion) that upon
increasing the coupling up to a critical value still small enough to allow for
weak-coupling Markovian master equations, a new relaxation regime can occur. In
that regime, complex frequencies lose their real parts such that the process
becomes overdamped. Our results call into question the standard belief that
overdamping is exclusively a strong coupling feature. | 0510164v1 |
2006-06-07 | Comment on "Optimum Quantum Error Recovery using Semidefinite Programming" | In a recent paper ([1]=quant-ph/0606035) it is shown how the optimal recovery
operation in an error correction scheme can be considered as a semidefinite
program. As a possible future improvement it is noted that still better error
correction might be obtained by optimizing the encoding as well. In this note
we present the result of such an improvement, specifically for the four-bit
correction of an amplitude damping channel considered in [1]. We get a strict
improvement for almost all values of the damping parameter. The method (and the
computer code) is taken from our earlier study of such correction schemes
(quant-ph/0307138). | 0606059v1 |
2006-09-19 | Quantum master equations from classical Lagrangians with two stochastic forces | We show how a large family of master equations, describing quantum Brownian
motion of a harmonic oscillator with translationally invariant damping, can be
derived within a phenomenological approach, based on the assumption that an
environment can be simulated by two classical stochastic forces. This family is
determined by three time-dependent correlation functions (besides the frequency
and damping coefficients), and it includes as special cases the known master
equations, whose dissipative part is bilinear with respect to the operators of
coordinate and momentum. | 0609144v3 |
2006-10-16 | Local noise can enhance entanglement teleportation | Recently we have considered two-qubit teleportation via mixed states of four
qubits and defined the generalized singlet fraction. For single-qubit
teleportation, Badziag {\em et al.} [Phys. Rev. A {\bf 62}, 012311 (2000)] and
Bandyopadhyay [Phys. Rev. A {\bf 65}, 022302 (2002)] have obtained a family of
entangled two-qubit mixed states whose teleportation fidelity can be enhanced
by subjecting one of the qubits to dissipative interaction with the environment
via an amplitude damping channel. Here, we show that a dissipative interaction
with the local environment via a pair of time-correlated amplitude damping
channels can enhance fidelity of entanglement teleportation for a class of
entangled four-qubit mixed states. Interestingly, we find that this enhancement
corresponds to an enhancement in the quantum discord for some states. | 0610125v1 |
2006-11-24 | High fidelity transfer of an arbitrary quantum state between harmonic oscillators | It is shown that by switching a specific time-dependent interaction between a
harmonic oscillator and a transmission line (a waveguide, an optical fiber,
etc.) the quantum state of the oscillator can be transferred into that of
another oscillator coupled to the distant other end of the line, with a
fidelity that is independent of the initial state of both oscillators. For a
transfer time $T$, the fidelity approaches 1 exponentially in $\gamma T$ where
$\gamma$ is a characteristic damping rate. Hence, a good fidelity is achieved
even for a transfer time of a few damping times. Some implementations are
discussed. | 0611249v1 |
2006-12-05 | Quantum Brownian motion and the second law of thermodynamics | We consider a single harmonic oscillator coupled to a bath at zero
temperature. As is well known, the oscillator then has a higher average energy
than that given by its ground state. Here we show analytically that for a
damping model with arbitrarily discrete distribution of bath modes and damping
models with continuous distributions of bath modes with cut-off frequencies,
this excess energy is less than the work needed to couple the system to the
bath, therefore, the quantum second law is not violated. On the other hand, the
second law may be violated for bath modes without cut-off frequencies, which
are, however, physically unrealistic models. | 0612038v1 |
2007-05-08 | Minimal qudit code for a qubit in the phase-damping channel | Using the stabilizer formalism we construct the minimal code into a
D-dimensional Hilbert space (qudit) to protect a qubit against phase damping.
The effectiveness of this code is then studied by means of input-output
fidelity. | 0705.1099v3 |
2007-05-10 | Anomalous Diffusion of particles with inertia in external potentials | Recently a new type of Kramers-Fokker-Planck Equation has been proposed [R.
Friedrich et al. Phys. Rev. Lett. {\bf 96}, 230601 (2006)] describing anomalous
diffusion in external potentials. In the present paper the explicit cases of a
harmonic potential and a velocity-dependend damping are incorporated. Exact
relations for moments for these cases are presented and the asymptotic
behaviour for long times is discussed. Interestingly the bounding potential and
the additional damping by itself lead to a subdiffussive behaviour, while
acting together the particle becomes localized for long times. | 0705.1480v1 |
2007-05-31 | Stability of Solutions to Damped Equations with Negative Stiffness | This article concerns the stability of a model for mass-spring systems with
positive damping and negative stiness. It is well known that when the
coefficients are frozen in time the system is unstable. Here we find conditions
on the variable cofficients to prove stability. In particular, we disprove the
believe that if the eigenvalues of the system change slowly in time the system
remains unstable. We extend some of our results for nonlinear systems. | 0705.4670v1 |
2007-06-13 | Polymers in a vacuum | In a variety of situations, isolated polymer molecules are found in a vacuum
and here we examine their properties. Angular momentum conservation is shown to
significantly alter the average size of a chain and its conservation is only
broken slowly by thermal radiation. The time autocorrelation for monomer
position oscillates with a characteristic time proportional to chain length.
The oscillations and damping are analyzed in detail. Short range repulsive
interactions suppress oscillations and speed up relaxation but stretched chains
still show damped oscillatory time correlations. | 0706.2001v1 |
2007-09-11 | Frequency and damping of the Scissors Mode of a Fermi gas | We calculate the frequency and damping of the scissors mode in a classical
gas as a function of temperature and coupling strength. Our results show good
agreement with the main features observed in recent measurements of the
scissors mode in an ultracold gas of $^6$Li atoms. The comparison between
theory and experiment involves no fitting parameters and thus allows an
identification of non-classical effects at and near the unitarity limit. | 0709.1617v2 |
2007-09-14 | Strong collisionless damping of the low-velocity branch of electromagnetic wave in plasmas with Maxwellian-like electron velocity distribution function | After approximate replacing of Maxwellian distribution exponent with the
rational polynomial fraction we have obtained precise analytical expression for
and calculated the principal value of logarithmically divergent integral in the
electron wave dispersion equation. At the same time our calculations have shown
the presence of strong collisionless damping of the electromagnetic
low-velocity (electron) wave in plasmas with Maxwellian-like electron velocity
distribution function at some small, of the order of several per cents,
differences from Maxwellian distribution in the main region of large electron
densities, however due to the differences in the distribution tail, where
electron density itself is negligibly small. | 0709.2206v1 |
2007-09-14 | Plasmons, plasminos and Landau damping in a quasiparticle model of the quark-gluon plasma | A phenomenological quasiparticle model is surveyed for 2+1 quark flavors and
compared with recent lattice QCD results. Emphasis is devoted to the effects of
plasmons, plasminos and Landau damping. It is shown that thermodynamic bulk
quantities, known at zero chemical potential, can uniquely be mapped towards
nonzero chemical potential by means of a thermodynamic consistency condition
and a stationarity condition. | 0709.2262v2 |
2007-10-24 | Spin dynamics of a trapped spin-1 Bose Gas above the Bose-Einstein transition temperature | We study collective spin oscillations in a spin-1 Bose gas above the
Bose-Einstein transition temperature. Starting from the Heisenberg equation of
motion, we derive a kinetic equation describing the dynamics of a thermal gas
with the spin-1 degree of freedom. Applying the moment method to the kinetic
equation, we study spin-wave collective modes with dipole symmetry. The dipole
modes in the spin-1 system are found to be classified into the three type of
modes. The frequency and damping rate are obtained as functions of the peak
density. The damping rate is characterized by three relaxation times associated
with collisions. | 0710.4419v2 |
2007-11-19 | Nonlinear mode conversion in monodomain magnetic squares | Modifications of spatial distributions of dynamic magnetization corresponding
to spinwave eigenmodes of magnetic squares subjected to a strong microwave
excitation field have been studied experimentally and theoretically. We show
that an increase of the excitation power leads to a nonlinear generation of
long-wavelength spatial harmonics caused by the nonlinear cross coupling
between the eigenmodes. The analysis of the experimental data shows that this
process is mainly governed by the action of the nonlinear spin-wave damping.
This conclusion is further supported by the numerical calculations based on the
complex Ginzburg-Landau equation phenomenologically taking into account the
nonlinear damping. | 0711.2872v1 |
2007-12-18 | Weibel Instabilities in Dense Quantum Plasmas | The quantum effect on the Weibel instability in an unmagnetized plasma is
presented. Our analysis shows that the quantum effect tends to stabilize the
Weibel instability in the hydrodynamic regime, whereas it produces a new
oscillatory instability in the kinetic regime. A novel effect the quantum
damping, which is associated with the Landau damping, is disclosed. The new
quantum Weibel instability may be responsible for the generation of
non-stationary magnetic fields in compact astrophysical objects as well as in
the forthcoming intense laser-solid density plasma experiments. | 0712.2874v1 |
2008-01-18 | A qualitative perspective on the dynamics of a single-Cooper-pair box with a phase-damped cavity | In a recent paper Dajka, et.al., [J. Phys. A \textbf{40}, F879 (2007)]
predicted that some composite systems can be entangled forever even if coupled
with a thermal bath. We analyze the transient entanglement of a
single-Cooper-pair box biased by a classical voltage and irradiated by a
quantized field and find the unusual feature that the phase-damped cavity can
lead to a long-lived entanglement. The results show an asymptotic value of the
idempotency defect (concurrence) which embodies coherence loss (entanglement
survival), independent of the interaction development by dependent critically
on environment. | 0801.2905v2 |
2008-02-28 | Current driven spin-wave instability triggered by the anomalous Hall effect | We studied the effect of strong electric current on spin waves interacting
relativistically with the current. The spin-wave spectrum is calculated at
arbitrary direction of the wave vector. It is shown that the alternating Hall
current generated by the alternating magnetic moment of the spin waves, reduces
the spin-wave damping. At strong enough unpolarized dc current the damping
changes sign, and the spin-wave amplitude starts to increase exponentially fast
with time. The critical current for the spin-wave instability is determined
mainly by the anomalous Hall effect, and can be much smaller than that for the
spin-torque mechanism of instability. | 0802.4150v1 |
2008-03-31 | Spectral Modeling of Magnetohydrodynamic Turbulent Flows | We present a dynamical spectral model for Large Eddy Simulation of the
incompressible magnetohydrodynamic (MHD) equations based on the Eddy Damped
Quasi Normal Markovian approximation. This model extends classical spectral
Large Eddy Simulations for the Navier-Stokes equations to incorporate general
(non Kolmogorovian) spectra as well as eddy noise. We derive the model for MHD
and show that introducing a new eddy-damping time for the dynamics of spectral
tensors in the absence of equipartition between the velocity and magnetic
fields leads to better agreement with direct numerical simulations, an
important point for dynamo computations. | 0803.4499v1 |
2008-04-10 | Trapped Phase-Segregated Bose-Fermi Mixtures and their Collective Excitations | Recent progress in the field of ultracold gases has allowed the creation of
phase-segregated Bose-Fermi systems. We present a theoretical study of their
collective excitations at zero temperature. As the fraction of fermion to boson
particle number increases, the collective mode frequencies take values between
those for a fully bosonic and those for a fully fermionic cloud, with damping
in the intermediate region. This damping is caused by fermions which are
resonantly driven at the interface. | 0804.1759v2 |
2008-04-14 | Size dependence of multipolar plasmon resonance frequencies and damping rates in simple metal spherical nanoparticles | Multipolar plasmon oscillation frequencies and corresponding damping rates
for nanospheres formed of the simplest free-electron metals are studied. The
possibility of controlling plasmon features by choosing the size and dielectric
properties of the sphere surroundings is discussed. Optical properties of the
studied metals are described within the Drude-Sommerfeld model of the
dielectric function with effective parameters acounting for the contribution of
conduction electrons and of interband transitions. No approximation is made in
respect of the size of a particle; plasmon size characteristics are described
rigorously. The results of our experiment on sodium nanodroplets [1] are
compared with the oscillation frequency size dependence of dipole and
quadrupole plasmon. | 0804.2156v1 |
2008-06-05 | Thermally Assisted Spin Hall Effect | The spin polarized charge transport is systematically analyzed as a thermally
driven stochastic process. The approach is based on Kramers' equation
describing the semiclassical motion under the inclusion of stochastic and
damping forces. Due to the relativistic spin-orbit coupling the damping
experiences a relativistic correction leading to an additional contribution
within the spin Hall conductivity. A further contribution to the conductivity
is originated from the averaged underlying crystal potential, the mean value of
which depends significantly on the electric field. We derive an exact
expression for the electrical conductivity. All corrections are estimated in
lowest order of a relativistic approach and in the linear response regime. | 0806.0948v1 |
2008-06-13 | General Solution of the Quantum Damped Harmonic Oscillator II : Some Examples | In the preceding paper (arXiv : 0710.2724 [quant-ph]) we have constructed the
general solution for the master equation of quantum damped harmonic oscillator,
which is given by the complicated infinite series in the operator algebra
level. In this paper we give the explicit and compact forms to solutions
(density operators) for some initial values. In particular, the compact one for
the initial value based on a coherent state is given, which has not been given
as far as we know. Moreover, some related problems are presented. | 0806.2169v1 |
2008-08-27 | Entanglement dynamics of two-qubit system in different types of noisy channels | In this paper, we study entanglement dynamics of a two-qubit extended
Werner-like state locally interacting with independent noisy channels, i.e.,
amplitude damping, phase damping and depolarizing channels. We show that the
purity of initial entangled state has direct impacts on the entanglement
robustness in each noisy channel. That is, if the initial entangled state is
prepared in mixed instead of pure form, the state may exhibit entanglement
sudden death (ESD) and/or be decreased for the critical probability at which
the entanglement disappear. | 0808.3690v1 |
2008-09-01 | Heatons induced by attosecond laser pulses | In this paper the dynamics of the interaction of attosecond laser pulses with
matter is investigated. It will be shown that the master equation: modified
Klein-Gordon equation describes the propagation of the heatons. Heatons are the
thermal wave packets. When the duration of the laser pulses is of the order of
attosecond the heaton thermal wave packets are nondispersive objects. For
infinite time the heatons are damped with damping factor of the order of
relaxation time for thermal processes. | 0809.0204v1 |
2008-10-09 | Heat conduction in 2D strongly-coupled dusty plasmas | We perform non-equilibrium simulations to study heat conduction in
two-dimensional strongly coupled dusty plasmas. Temperature gradients are
established by heating one part of the otherwise equilibrium system to a higher
temperature. Heat conductivity is measured directly from the stationary
temperature profile and heat flux. Particular attention is paid to the
influence of damping effect on the heat conduction. It is found that the heat
conductivity increases with the decrease of the damping rate, while its
magnitude agrees with previous experimental measurement. | 0810.1623v2 |
2008-10-21 | Structurally damped plate and wave equations with random point force in arbitrary space dimensions | In this paper we consider structurally damped plate and wave equations with
point and distributed random forces. In order to treat space dimensions more
than one, we work in the setting of $L^q$--spaces with (possibly small)
$q\in(1,2)$. We establish existence, uniqueness and regularity of mild and weak
solutions to the stochastic equations employing recent theory for stochastic
evolution equations in UMD Banach spaces. | 0810.3898v2 |
2008-12-16 | A picogram and nanometer scale photonic crystal opto-mechanical cavity | We describe the design, fabrication, and measurement of a cavity
opto-mechanical system consisting of two nanobeams of silicon nitride in the
near-field of each other, forming a so-called "zipper" cavity. A photonic
crystal patterning is applied to the nanobeams to localize optical and
mechanical energy to the same cubic-micron-scale volume. The picrogram-scale
mass of the structure, along with the strong per-photon optical gradient force,
results in a giant optical spring effect. In addition, a novel damping regime
is explored in which the small heat capacity of the zipper cavity results in
blue-detuned opto-mechanical damping. | 0812.2953v1 |
2009-02-12 | Discrete breathers in a forced-damped array of coupled pendula: Modeling, Computation and Experiment | In this work, we present a mechanical example of an experimental realization
of a stability reversal between on-site and inter-site centered localized
modes. A corresponding realization of a vanishing of the Peierls-Nabarro
barrier allows for an experimentally observed enhanced mobility of the
localized modes near the reversal point. These features are supported by
detailed numerical computations of the stability and mobility of the discrete
breathers in this system of forced and damped coupled pendula. Furthermore,
additional exotic features of the relevant model, such as dark breathers are
briefly discussed. | 0902.2129v1 |
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