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2005-04-25
|
Radiative Effect on Particle Acceleration via Relativistic Electromagnetic Expansion
|
The radiation damping effect on the diamagnetic relativistic pulse
accelerator (DRPA) is studied in two-and-half dimensional Particle-in-Cell
(PIC) simulation with magnetized electron-positron plasmas. Self-consistently
solved radiation damping force converts particle energy to radiation energy.
The DRPA is still robust with radiation, and the Lorentz factor of the most
high energy particles reach more than two thousand before they decouple from
the electromagnetic pulse. Resulted emitted power from the pulse front is lower
in the radiative case than the estimation from the non-radiative case due to
the radiation damping. The emitted radiation is strongly linearly polarized and
peaked within few degrees from the direction of Poynting flux.
|
0504561v1
|
1999-05-06
|
Collective and chaotic motion in self-bound many-body systems
|
We investigate the interplay of collective and chaotic motion in a classical
self-bound N-body system with two-body interactions. This system displays a
hierarchy of three well separated time scales that govern the onset of chaos,
damping of collective motion and equilibration. Comparison with a mean-field
problem shows that damping is mainly due to dephasing. The Lyapunov exponent,
damping and equilibration rates depend mildly on the system size N.
|
9905007v2
|
1997-05-12
|
Damping of Oscillations in Layer-by-Layer Growth
|
We present a theory for the damping of layer-by-layer growth oscillations in
molecular beam epitaxy. The surface becomes rough on distances larger than a
layer coherence length which is substantially larger than the diffusion length.
The damping time can be calculated by a comparison of the competing roughening
and smoothening mechanisms. The dependence on the growth conditions,
temperature and deposition rate, is characterized by a power law. The
theoretical results are confirmed by computer simulations.
|
9705100v1
|
1999-09-17
|
Thermoelastic Damping in Micro- and Nano-Mechanical Systems
|
The importance of thermoelastic damping as a fundamental dissipation
mechanism for small-scale mechanical resonators is evaluated in light of recent
efforts to design high-Q micrometer- and nanometer-scale electro-mechanical
systems (MEMS and NEMS). The equations of linear thermoelasticity are used to
give a simple derivation for thermoelastic damping of small flexural vibrations
in thin beams. It is shown that Zener's well-known approximation by a
Lorentzian with a single thermal relaxation time slightly deviates from the
exact expression.
|
9909271v1
|
2000-10-01
|
Super-Radiance and the Unstable Photon Oscillator
|
If the damping of a simple harmonic oscillator from a thermally random force
is sufficiently strong, then the oscillator may become unstable. For a photon
oscillator (radiatively damped by electric dipole moments), the instability
leads to a low temperature Hepp-Lieb-Preparata super-radiant phase transition.
The stable oscillator regime is described by the free energy of the
conventional Casimir effect. The unstable (strongly damped) oscillator has a
free energy corresponding to Dicke super-radiance.
|
0010013v1
|
2001-08-07
|
Non-damped Acoustic Plasmon and Superconductivity in Single Wall Carbon Nanotubes
|
We show that non-damped acoustic plasmons exist in single wall carbon
nanotubes (SWCNT) and propose that the non-damped acoustic plasmons may mediate
electron-electron attraction and result in superconductivity in the SWCNT. The
superconducting transition temperature Tc for the SWCNT (3,3) obtained by this
mechanism agrees with the recent experimental result (Z. K. Tang et al, Science
292, 2462(2001)). We also show that it is possible to get higher Tc up to 99 K
by doping the SWCNT (5,5).
|
0108124v2
|
2001-12-16
|
The Damping of the Bose-Condensate Oscillations in a Trap at Zero Temperature
|
We discuss an existence of the damping for the radial condensate oscillations
in a cylindric trap at zero temperature. The damping is a result of the
parametric resonance leading to energy transfer from the coherent condensate
oscillations to the longitudinal sound waves within a finite frequency
interval. The parametric resonance is due to the oscillations of the sound
velocity. The triggering amplitudes at zero temperature are associated with the
zero-point oscillations.
|
0112292v1
|
2002-06-13
|
Beliaev damping of quasi-particles in a Bose-Einstein condensate
|
We report a measurement of the suppression of collisions of quasi-particles
with ground state atoms within a Bose-Einstein condensate at low momentum.
These collisions correspond to Beliaev damping of the excitations, in the
previously unexplored regime of the continuous quasi-particle energy spectrum.
We use a hydrodynamic simulation of the expansion dynamics, with the Beliaev
damping cross-section, in order to confirm the assumptions of our analysis.
|
0206234v1
|
2002-06-28
|
Accidental suppression of Landau damping of the transverse breathing mode in elongated Bose-Einstein condensates
|
We study transverse radial oscillations of an elongated Bose-Einstein
condensate using finite temperature simulations, in the context of a recent
experiment at ENS. We demonstrate the existence of a mode corresponding to an
in-phase collective oscillation of both the condensate and thermal cloud.
Excitation of this mode accounts for the very small damping rate observed
experimentally, and we find excellent quantitative agreement between experiment
and theory. In contrast to other condensate modes, interatomic collisions are
found to be the dominant damping mechanism in this case.
|
0206582v1
|
2004-04-19
|
Nonlinear response of superparamagnets with finite damping: an analytical approach
|
The strongly damping-dependent nonlinear dynamical response of classical
superparamagnets is investigated by means of an analytical approach. Using
rigorous balance equations for the spin occupation numbers a simple approximate
expression is derived for the nonlinear susceptibility. The results are in good
agreement with those obtained from the exact (continued-fraction) solution of
the Fokker-Planck equation. The formula obtained could be of assistance in the
modelling of the experimental data and the determination of the damping
coefficient in superparamagnets.
|
0404445v1
|
2005-03-03
|
Collapse of thermal activation in moderately damped Josephson junctions
|
We study switching current statistics in different moderately damped
Josephson junctions: a paradoxical collapse of the thermal activation with
increasing temperature is reported and explained by interplay of two
conflicting consequences of thermal fluctuations, which can both assist in
premature escape and help in retrapping back into the stationary state. We
analyze the influence of dissipation on the thermal escape by tuning the
damping parameter with a gate voltage, magnetic field, temperature and an
in-situ capacitor.
|
0503067v1
|
2006-03-13
|
Universal features of the defect-induced damping of lattice vibrations
|
It is shown that any defect gives an Ohmic contribution to the damping of any
normal mode of the crystal lattice with nonzero wavevector which does not
vanish at zero temperature. This explains the large phason damping observed at
low temperatures in incommensurate phases, and might be a key factor to
understand the linear-in-$T$ specific heat observed in a number of real
dielectrics at low enough temperatures.
|
0603343v2
|
2006-04-25
|
Spin Precession and Avalanches
|
In many magnetic materials, spin dynamics at short times are dominated by
precessional motion as damping is relatively small. In the limit of no damping
and no thermal noise, we show that for a large enough initial instability, an
avalanche can transition to an ergodic phase where the state is equivalent to
one at finite temperature, often above that for ferromagnetic ordering. This
dynamical nucleation phenomenon is analyzed theoretically. For small finite
damping the high temperature growth front becomes spread out over a large
region. The implications for real materials are discussed.
|
0604563v1
|
2007-02-11
|
Non-Markovian coherence dynamics of driven spin boson model: damped quantum beat or large amplitude coherence oscillation
|
The dynamics of driven spin boson model is studied analytically by means of
the perturbation approach based on a unitary transformation. We gave the
analytical expression for the population difference and coherence of the two
level system. The results show that in the weak driven case, the population
difference present damped coherent oscillation (single or double frequency) and
the frequencies depend on the initial state. The coherence exhibit damped
oscillation with Rabi frequency. When driven field is strong enough, the
population difference exhibit undamped large-amplitude coherent oscillation.
The results easily return to the two extreme cases without dissipation or
without periodic driven.
|
0702268v1
|
2005-05-10
|
Highly Damped Quasinormal Modes of Generic Single Horizon Black Holes
|
We calculate analytically the highly damped quasinormal mode spectra of
generic single-horizon black holes using the rigorous WKB techniques of
Andersson and Howls\cite{Andersson}. We thereby provide a firm foundation for
previous analysis, and point out some of their possible limitations. The
numerical coefficient in the real part of the highly damped frequency is
generically determined by the behavior of coupling of the perturbation to the
gravitational field near the origin, as expressed in tortoise coordinates. This
fact makes it difficult to understand how the famous $ln(3)$ could be related
to the quantum gravitational microstates near the horizon.
|
0505044v1
|
2006-05-01
|
Stability and quasinormal modes of the massive scalar field around Kerr black holes
|
We find quasinormal spectrum of the massive scalar field in the background of
the Kerr black holes. We show that all found modes are damped under the
quasinormal modes boundary conditions when $\mu M$ is not large, thereby
implying stability of the massive scalar field. This complements the region of
stability determined by the Beyer inequality for large masses of the field. We
show that, similar to the case of a non-rotating black holes, the massive term
of the scalar field does not contribute in the regime of high damping. Thereby,
the high damping asymptotic should be the same as for the massless scalar
field.
|
0605013v1
|
1992-04-06
|
Comment on ``High Temperature Fermion Propagator -- Resummation and Gauge Dependence of the Damping Rate''
|
Baier et al. have reported the damping rate of long-wavelength fermionic
excitations in high-temperature QED and QCD to be gauge-fixing-dependent even
within the resummation scheme due to Braaten and Pisarski. It is shown that
this problem is caused by the singular nature of the on-shell expansion of the
fermion self-energy in the infra-red. Its regularization reveals that the
alleged gauge dependence pertains to the residue rather than the pole of the
fermion propagator, so that in particular the damping constant comes out
gauge-independent, as it should.
|
9204210v1
|
1993-02-09
|
Damping rates for moving particles in hot QCD
|
Using a program of perturbative resummation I compute the damping rates for
fields at nonzero spatial momentum to leading order in weak coupling in hot
$QCD$. Sum rules for spectral densities are used to simplify the calculations.
For massless fields the damping rate has an apparent logarithmic divergence in
the infrared limit, which is cut off by the screening of static magnetic fields
(``magnetic mass''). This demonstrates how at high temperature even
perturbative quantities are sensitive to nonperturbative phenomenon.
|
9302242v1
|
1994-04-21
|
Is \lq\lq Heavy Quark Damping Rate Puzzle'' in Hot QCD Really the Puzzle?
|
Within the framework of perturbative resummation scheme of Pisarski and
Braaten, the decay- or damping-rate of a moving heavy quark (muon) to leading
order in weak coupling in hot QCD (QED) is examined. Although, as is well
known, the conventionally-defined damping rate diverges logarithmically at the
infrared limit, shown is that no such divergence appears in the physically
measurable decay rate. The cancellation occurs between the contribution from
the \lq\lq real'' decay diagram and the contribution from the diagrams with
\lq\lq thermal radiative correction''.
|
9404318v1
|
1996-01-12
|
Damping Rate of a Scalar Particle in Hot Scalar QED
|
In contrast to the damping of partons in a quark-gluon plasma, the damping of
a scalar particle in a hot scalar QED plasma can be calculated to leading order
for the whole momentum range using the Braaten-Pisarski method. In this way the
evolution of the logarithmic infrared singularity caused by the exchange of a
transverse photon from soft to hard momenta can be studied.
|
9601254v1
|
1996-09-17
|
Damping Rate of Quasiparticles in Degenerate Ultrarelativistic Plasmas
|
We compute the damping rate of a fermion in a dense relativistic plasma at
zero temperature. Just above the Fermi sea, the damping rate is dominated by
the exchange of soft magnetic photons (or gluons in QCD) and is proportional to
$(E-\mu)$, where E is the fermion energy and $\mu$ the chemical potential. We
also compute the contribution of soft electric photons and of hard photons. As
in the nonrelativistic case, the contribution of longitudinal photons is
proportional to $(E-\mu)^2$, and is thus non leading in the relativistic case.
|
9609369v1
|
1997-05-28
|
Classical Statistical Mechanics and Landau Damping
|
We study the retarded response function in scalar $\phi^4$-theory at finite
temperature. We find that in the high-temperature limit the imaginary part of
the self-energy is given by the classical theory to leading order in the
coupling. In particular the plasmon damping rate is a purely classical effect
to leading order, as shown by Aarts and Smit. The dominant contribution to
Landau damping is given by the propagation of classical fields in a heat bath
of non-interacting fields.
|
9705452v1
|
1997-12-01
|
A potential infrared problem with the damping rates for gluons with soft momentum in hot QCD
|
We calculate the damping rate $\gamma_l$ for longitudinal gluons with zero
momentum in finite high temperature QCD and show that some of its contributing
terms are infrared divergent. This is in contrast with the expectation that
this damping rate is to be equal to the corresponding one $\gamma_t$ for
transverse gluons which is known to be finite. Our calculation was motivated by
the fact that similar divergent terms occur when we calculated in a previous
work $\gamma_t$ to order $ p^2$, p being the momentum of the gluon. After we
present our results, we briefly discuss them.
|
9712210v1
|
1998-04-21
|
The Plasmon Damping Rate for T -> T_C
|
The plasmon damping rate in scalar field theory is computed close to the
critical temperature. It is shown that the divergent result obtained in
perturbation theory is a consequence of neglecting the thermal renormalization
of the coupling. Taking this effect into account, a vanishing damping rate is
obtained, leading to the critical slowing down of the equilibration process.
|
9804351v2
|
1998-10-06
|
Self-consistent Study on Color Transport in the Quark Gluon Plasma at Finite Chemical Potential
|
We calculate the relaxation time self-consistently to study the damping of
collective color modes and the color conductivity in a QGP by deriving
self-consistent equations for the damping rates of gluons and quarks to leading
order QCD by TFD including a chemical potential for quarks. We show that the
damping rates are not sensitive to the chemical potential whereas color
conductivity is enhanced considerably.
|
9810256v1
|
1999-02-19
|
The problem of nonlinear Landau damping in quark-gluon plasma
|
On the basis of the semiclassical equations for quark-gluon plasma (QGP) and
Yang-Mills equation, the generalized kinetic equation for waves with regard to
its interaction is obtained. The physical mechanisms defining nonlinear
scattering of a plasmon by QGP particles are analysed. The problem on a
connection of nonlinear Landau damping rate of longitudinal oscillation with
damping rate, obtained on the basis of hard thermal loops approximation, is
considered.
|
9902397v2
|
1999-07-21
|
A Slavnov-Taylor identity and equality of damping rates for static transverse and longitudinal gluons in hot QCD
|
A Slavnov-Taylor identity is derived for the gluon polarization tensor in hot
QCD. We evaluate its implications for damping of gluonic modes in the plasma.
Applying the identity to next to the leading order in hard-thermal-loop
resummed perturbation theory, we derive the expected equality of damping rates
for static transverse and longitudinal (soft) gluons. This is of interest also
in view of deviating recent reports of $\gamma_t(p=0)\neq\gamma_l(p=0)$ based
on a direct calculation of $\gamma_l(p=0)$.
|
9907439v1
|
2000-09-15
|
Fermion Damping Rate Effects in Cold Dense Matter
|
We review the non-Fermi or marginal liquid behavior of a relativistic QED
plasma. In this medium a quasiparticle has a damping rate that depends linearly
on the distance between its energy and the Fermi surface. We stress that this
dependence is due to the long-range character of the magnetic interactions in
the medium. Finally, we study how the quark damping rate modifies the gap
equation of color superconductivity, reducing the value of the gap at the Fermi
surface.
|
0009182v1
|
2001-07-19
|
Photon Damping Caused by Electron-Positron Pair Production in a Strong Magnetic Field
|
Damping of an electromagnetic wave in a strong magnetic field is analyzed in
the kinematic region near the threshold of electron-positron pair production.
Damping of the electromagnetic field is shown to be noticeably nonexponential
in this region. The resulting width of the photon $\gamma \to e^+ e^-$ decay is
considerably smaller than previously known results.
|
0107217v1
|
2004-09-27
|
Damping of electromagnetic waves due to electron-positron pair production
|
The problem of the backreaction during the process of electron-positron pair
production by a circularly polarized electromagnetic wave propagating in a
plasma is investigated. A model based on the relativistic Boltzmann-Vlasov
equation with a source term corresponding to the Schwinger formula for the pair
creation rate is used. The damping of the wave, the nonlinear up-shift of its
frequency due to the plasma density increase and the effect of the damping on
the wave polarization and on the background plasma acceleration are
investigated as a function of the wave amplitude.
|
0409301v1
|
2005-10-25
|
Infrared behavior of the dispersion relations in high-temperature scalar QED
|
We investigate the infrared properties of the next-to-leading-order
dispersion relations in scalar quantum electrodynamics at high temperature in
the context of hard-thermal-loop perturbation theory. Specifically, we
determine the damping rate and the energy for scalars with ultrasoft momenta.
We show by explicit calculations that an early external-momentum expansion,
before the Matsubara sum is performed, gives exactly the same result as a late
one. The damping rate is obtained up to fourth order included in the ultrasoft
momentum and the energy up to second order. The damping rate is found sensitive
in the infrared whereas the energy not.
|
0510330v1
|
2006-11-09
|
Lepton asymmetry in the primordial gravitational wave spectrum
|
Effects of neutrino free streaming is evaluated on the primordial spectrum of
gravitational radiation taking both neutrino chemical potential and masses into
account. The former or the lepton asymmetry induces two competitive effects,
namely, to increase anisotropic pressure, which damps the gravitational wave
more, and to delay the matter-radiation equality time, which reduces the
damping. The latter effect is more prominent and a large lepton asymmetry would
reduce the damping. We may thereby be able to measure the magnitude of lepton
asymmetry from the primordial gravitational wave spectrum.
|
0611121v1
|
2005-03-17
|
A New Approach to Canonical Quantization of the Radiation Damping
|
Inspired in some works about quantization of dissipative systems, in
particular of the damped harmonic oscillator\cite{MB,RB,12}, we consider the
dissipative system of a charge interacting with its own radiation, which
originates the radiation damping (RD). Using the indirect Lagrangian
representation we obtained a Lagrangian formalism with a Chern-Simons-like
term. A Hamiltonian analysis is also done, what leads to the quantization of
the system.
|
0503135v1
|
2003-09-15
|
Eigenfrequencies and expansions for damped wave equations
|
We study eigenfrequencies and propagator expansions for damped wave equations
on compact manifolds. Under the assumption of geometric control, the propagator
is shown to admit an expansion in terms of finitely many eigenmodes near the
real axis, with an error term exponentially decaying in time. In the presence
of a nondegenerate elliptic closed geodesic not meeting the support of the
damping coefficient, we show that there exists a sequence of eigenfrequencies
converging rapidly to the real axis. In the case of Zoll manifolds, we show
that the propagator can be expanded in terms of clusters of the
eigenfrequencies in the entire spectral band.
|
0309250v1
|
2004-06-02
|
Instability results for the damped wave equation in unbounded domains
|
We extend some previous results for the damped wave equation in bounded
domains in Euclidean spaces to the unbounded case. In particular, we show that
if the damping term is of the form $\alpha a$ with bounded $a$ taking on
negative values on a set of positive measure, then there will always exist
unbounded solutions for sufficiently large positive $\alpha$.
In order to prove these results, we generalize some existing results on the
asymptotic behaviour of eigencurves of one-parameter families of Schrodinger
operators to the unbounded case, which we believe to be of interest in their
own right.
|
0406041v1
|
1997-07-20
|
Effects of gluon damping rate on the viscosity coefficient of the quark-gluon plasma at finite chemical potential
|
By considering the Debye screening and damping rate of gluons, the viscosity
coefficient of the quark-gluon plasma was evaluated via real-time finite
temperature QCD in the relaxation time approximation at finite temperature and
chemical potential . The results show that both the damping rate and the
chemical potential cause considerable enhancements to the viscosity coefficient
of hot dense quark-gluon plasma.
|
9707033v1
|
2002-12-11
|
Rotational Damping and Compound Formation in Warm Rotating Nuclei
|
The rotational damping width \Gamma_{rot} and the compound damping width
\Gamma_{comp} are two fundamental quantities that characterize rapidly rotating
compound nuclei having finite thermal excitation energy. A two-component
structure in the strength function of consecutive E2 transitions reflects the
two widths, and it causes characteristic features in the double and triple
gamma-ray spectra. We discuss a new method to extract experimentally values of
\Gamma_{rot} and \Gamma_{comp}. The first preliminary result of this method is
presented.
|
0212050v1
|
2003-07-27
|
Chaos and rotational damping in particle-rotor model
|
The onset of chaos and the mechanism of rotational damping are studied in an
exactly soluble particle-rotor model. It is shown that the degree of chaoticity
as inferred from the statistical measures is closely related to the onset of
rotational damping obtained using the model Hamiltonian.
|
0307104v2
|
1997-07-10
|
Supersymmetric partner chirping of Newtonian free damping
|
We connect the classical free damping cases by means of Rosner's construction
in supersymmetric quantum mechanics. Starting with the critical damping, one
can obtain in the underdamping case a chirping of instantaneous physical
frequency \omega ^{2}(t) \propto \omega_{u}^{2}sech^2(\omega_{u}t), whereas in
the overdamped case the "chirping" is of the (unphysical) type \omega
^{2}(t)\propto\omega_{o}^{2}sec^{2}(\omega_{o}t), where \omega_{u}$ and
$\omega_{o} are the underdamped and overdamped frequency parameters,
respectively
|
9707012v4
|
2000-04-10
|
Ermakov-Lewis angles for one-parameter supersymmetric families of Newtonian free damping modes
|
We apply the Ermakov-Lewis procedure to the one-parameter damped modes
\tilde{y} recently introduced by Rosu and Reyes, which are related to the
common Newtonian free damping modes y by the general Riccati solution [H.C.
Rosu and M. Reyes, Phys. Rev. E 57, 4850 (1998), physics/9707019]. In
particular, we calculate and plot the angle quantities of this approach that
can help to distinguish these modes from the common y modes
|
0004014v4
|
2002-10-29
|
Model of Internal Friction Damping in Solids
|
A model for harmonic oscillator damping due to the internal friction of
solids has been developed, based on considerations of a long period pendulum.
The assumption of a complex elastic modulus to describe stress-strain
hysteresis in the support structure of the pendulum yields an expression for
the figure of merit Q that agrees with many experiments involving material
damping. As such, the approximations of this linear model stand in contrast
with common theory.
|
0210121v1
|
2003-06-11
|
Nonlinear Damping of the 'Linear' Pendulum
|
This study shows that typical pendulum dynamics is far from the simple
equation of motion presented in textbooks. A reasonably complete damping model
must use nonlinear terms in addition to the common linear viscous expression.
In some cases a nonlinear substitute for assumed linear damping may be more
appropriate. Even for exceptional cases where all nonlinearity may be ignored,
it is shown that viscous dissipation involves subtleties that can lead to huge
errors when ignored.
|
0306081v1
|
2003-07-02
|
Harmonic Oscillator Potential to describe Internal Dissipation
|
Assuming that a constant potential energy function has meaning for a
dissipated harmonic oscillator, then an important issue is the time dependence
of the turning points. Turning point studies demonstrate that the common model
of external (viscous) damping fails to properly describe those many systems
where structural (internal friction) damping is the most important source of
dissipation. For internal friction damping, the better model of potential
energy is one in which the function is not stationary.
|
0307016v1
|
2004-08-19
|
Beyond the Linear Damping Model for Mechanical Harmonic Oscillators
|
The steady state motion of a folded pendulum has been studied using
frequencies of drive that are mainly below the natural (resonance) frequency of
the instrument. Although the free-decay of this mechanical oscillator appears
textbook exponential, the steady state behavior of the instrument for
sub-resonance drive can be remarkably complex. Although the response cannot be
explained by linear damping models, the general features can be understood with
the nonlinear, modified Coulomb damping model developed by the author.
|
0408091v1
|
1998-01-28
|
Phenomenological damping in trapped atomic Bose-Einstein condensates
|
The method of phenomenological damping developed by Pitaevskii for
superfluidity near the $\lambda$ point is simulated numerically for the case of
a dilute, alkali, inhomogeneous Bose-condensed gas near absolute zero. We study
several features of this method in describing the damping of excitations in a
Bose-Einstein condensate. In addition, we show that the method may be employed
to obtain numerically accurate ground states for a variety of trap potentials.
|
9801064v1
|
1998-04-06
|
Optimal quantum codes for preventing collective amplitude damping
|
Collective decoherence is possible if the departure between quantum bits is
smaller than the effective wave length of the noise field. Collectivity in the
decoherence helps us to devise more efficient quantum codes. We present a class
of optimal quantum codes for preventing collective amplitude damping to a
reservoir at zero temperature. It is shown that two qubits are enough to
protect one bit quantum information, and approximately $L+ 1/2 \log_2((\pi
L)/2)$ qubits are enough to protect $L$ qubit information when $L$ is large.
For preventing collective amplitude damping, these codes are much more
efficient than the previously-discovered quantum error correcting or avoiding
codes.
|
9804014v1
|
2000-01-12
|
Antibunching effect of the radiation field in a microcavity with a mirror undergoing heavily damping oscillation
|
The interaction between the radiation field in a microcavity with a mirror
undergoing damping oscillation is investigated. Under the heavily damping
cases, the mirror variables are adiabatically eliminated.
The the stationary conditions of the system are discussed. The small
fluctuation approximation around steady values is applied to analysis the
antibunching effect of the cavity field. The antibunching condition is given
under two limit cases.
|
0001036v1
|
2000-03-29
|
Disagreement between correlations of quantum mechanics and stochastic electrodynamics in the damped parametric oscillator
|
Intracavity and external third order correlations in the damped nondegenerate
parametric oscillator are calculated for quantum mechanics and stochastic
electrodynamics (SED), a semiclassical theory. The two theories yield greatly
different results, with the correlations of quantum mechanics being cubic in
the system's nonlinear coupling constant and those of SED being linear in the
same constant. In particular, differences between the two theories are present
in at least a mesoscopic regime. They also exist when realistic damping is
included. Such differences illustrate distinctions between quantum mechanics
and a hidden variable theory for continuous variables.
|
0003131v1
|
2002-02-15
|
Decoherence of Quantum Damped Oscillators
|
Quantum dissipation is studied within two model oscillators, the
Caldirola-Kanai (CK) oscillator as an open system with one degree of freedom
and the Bateman-Feshbach-Tikochinsky (BFT) oscillator as a closed system with
two degrees of freedom. Though these oscillators describe the same classical
damped motion, the CK oscillator retains the quantum coherence, whereas the
damped subsystem of the BFT oscillator exhibits both quantum decoherence and
classical correlation. Furthermore the amplified subsystem of the BFT
oscillator shows the same degree of quantum decohernce and classical
correlation.
|
0202089v1
|
2002-12-05
|
Time correlated quantum amplitude damping channel
|
We analyze the problem of sending classical information through qubit
channels where successive uses of the channel are correlated. This work extends
the analysis of C. Macchiavello and G. M. Palma to the case of a non-Pauli
channel - the amplitude damping channel. Using the channel description outlined
in S. Daffer, et al, we derive the correlated amplitude damping channel. We
obtain a similar result to C. Macchiavello and G. M. Palma, that is, that under
certain conditions on the degree of channel memory, the use of entangled input
signals may enhance the information transmission compared to the use of product
input signals.
|
0212032v1
|
2005-06-01
|
Quantum damped oscillator I: dissipation and resonances
|
Quantization of a damped harmonic oscillator leads to so called Bateman's
dual system. The corresponding Bateman's Hamiltonian, being a self-adjoint
operator, displays the discrete family of complex eigenvalues. We show that
they correspond to the poles of energy eigenvectors and the corresponding
resolvent operator when continued to the complex energy plane. Therefore, the
corresponding generalized eigenvectors may be interpreted as resonant states
which are responsible for the irreversible quantum dynamics of a damped
harmonic oscillator.
|
0506007v1
|
2005-10-19
|
The damped harmonic oscillator in deformation quantization
|
We propose a new approach to the quantization of the damped harmonic
oscillator in the framework of deformation quantization. The quantization is
performed in the Schr\"{o}dinger picture by a star-product induced by a
modified "Poisson bracket". We determine the eigenstates in the damped regime
and compute the transition probability between states of the undamped harmonic
oscillator after the system was submitted to dissipation.
|
0510150v1
|
2006-04-28
|
The characteristic function of optical evolution
|
The master equation of quantum optical density operator is transformed to the
equation of characteristic function. The parametric amplification and amplitude
damping as well as the phase damping are considered. The solution for the most
general initial quantum state is obtained for parametric amplification and
amplitude damping. The purity of one mode Gaussian system and the entanglement
of two mode Gaussian system are studied.
|
0604208v4
|
2007-01-13
|
Wave-particle duality in the damped harmonic oscillator
|
Quantization of the damped harmonic oscillator is taken as leitmotiv to
gently introduce elements of quantum probability theory for physicists. To this
end, we take (graduate) students in physics as entry level and explain the
physical intuition and motivation behind the, sometimes overwhelming, math
machinery of quantum probability theory.
The main text starts with the quantization of the (undamped) harmonic
oscillator from the Heisenberg and Schroedinger point of view. We show how both
treatments are special instances of a quantum probabilistic quantization
procedure: the second quantization functor. We then apply the second
quantization functor to the damped harmonic oscillator and interpret the
quantum dynamics of the position and energy operator as stochastic processes.
|
0701082v1
|
2007-04-11
|
Time dependence of joint entropy of oscillating quantum systems
|
The time dependent entropy (or Leipnik's entropy) of harmonic and damped
harmonic oscillators is extensively investigated by using time dependent wave
function obtained by the Feynman path integral method. Our results for simple
harmonic oscillator are in agrement with the literature. However, the joint
entropy of damped harmonic oscillator shows remarkable discontinuity with time
for certain values of damping factor. According to the results, the envelop of
the joint entropy curve increases with time monotonically. This results is the
general properties of the envelop of the joint entropy curve for quantum
systems.
|
0704.1370v3
|
2007-06-30
|
The squeezed generalized amplitude damping channel
|
Squeezing of a thermal bath introduces new features absent in an open quantum
system interacting with an uncorrelated (zero squeezing) thermal bath. The
resulting dynamics, governed by a Lindblad-type evolution, extends the concept
of a generalized amplitude damping channel, which corresponds to a dissipative
interaction with a purely thermal bath. Here we present the Kraus
representation of this map, which we call the squeezed generalized amplitude
damping channel. As an application of this channel to quantum information, we
study the classical capacity of this channel.
|
0707.0059v2
|
2007-07-09
|
Memory in a nonlocally damped oscillator
|
We analyze the new equation of motion for the damped oscillator. It differs
from the standard one by a damping term which is nonlocal in time and hence it
gives rise to a system with memory. Both classical and quantum analysis is
performed. The characteristic feature of this nonlocal system is that it breaks
local composition low for the classical Hamiltonian dynamics and the
corresponding quantum propagator.
|
0707.1199v2
|
2007-07-20
|
Dynamics of Bloch Oscillations in Disordered Lattice Potentials
|
We present a detailed analysis of the dynamics of Bloch oscillations of
Bose-Einstein condensates in disordered lattice potentials. Due to the disorder
and the interparticle interactions these oscillations undergo a dephasing,
reflected in a damping of the center of mass oscillations, which should be
observable under realistic experimental conditions. The interplay between
interactions and disorder is far from trivial, ranging from an
interaction-enhanced damping due to modulational instability for strong
interactions, to an interaction-reduced damping due to a dynamical screening of
the disorder potential.
|
0707.3131v1
|
2007-09-14
|
Damping of field-induced chemical potential oscillations in ideal two-band compensated metals
|
The field and temperature dependence of the de Haas-van Alphen oscillations
spectrum is studied for an ideal two-dimensional compensated metal. It is shown
that the chemical potential oscillations, involved in the frequency
combinations observed in the case of uncompensated orbits, are strongly damped
and can even be suppressed when the effective masses of the electron- and
hole-type orbits are the same. When magnetic breakdown between bands occurs,
this damping is even more pronounced and the Lifshits-Kosevich formalism
accounts for the data in a wide field range.
|
0709.2223v2
|
2007-09-14
|
Update on Ion Studies
|
The effect of ions has received one of the highest priorities in R&D for the
damping rings of the International Linear Collider(ILC). It is detrimental to
the performance of the electron damping ring. In this note, an update
concerning the ion studies for the ILC damping ring is given. We investigate
the gap role and irregular fill pattern in the ring.The ion density reduction
in different fills is calculated analytically. Simulation results are also
presented.
|
0709.2248v1
|
2007-10-03
|
Stability of a Nonlinear Axially Moving String With the Kelvin-Voigt Damping
|
In this paper, a nonlinear axially moving string with the Kelvin-Voigt
damping is considered. It is proved that the string is stable, i.e., its
transversal displacement converges to zero when the axial speed of the string
is less than a certain critical value. The proof is established by showing that
a Lyapunov function corresponding to the string decays to zero exponentially.
It is also shown that the string displacement is bounded when a bounded
distributed force is applied to it transversally. Furthermore, a few open
problems regarding the stability and stabilization of strings with the
Kelvin-Voigt damping are stated.
|
0710.0872v1
|
2007-10-15
|
General Solution of the Quantum Damped Harmonic Oscillator
|
In this paper the general solution of the quantum damped harmonic oscillator
is given.
|
0710.2724v4
|
2008-02-21
|
Identification of Test Structures for Reduced Order Modeling of the Squeeze Film Damping in Mems
|
In this study the dynamic behaviour of perforated microplates oscillating
under the effect of squeeze film damping is analyzed. A numerical approach is
adopted to predict the effects of damping and stiffness transferred from the
surrounding ambient air to oscillating structures ; the effect of hole's cross
section and plate's extension is observed. Results obtained by F.E.M. models
are compared with experimental measurements performed by an optical
interferometric microscope.
|
0802.3076v1
|
2008-03-14
|
Current-induced noise and damping in non-uniform ferromagnets
|
In the presence of spatial variation of the magnetization direction, electric
current noise causes a fluctuating spin-transfer torque that increases the
fluctuations of the ferromagnetic order parameter. By the
fluctuation-dissipation theorem, the equilibrium fluctuations are related to
the magnetization damping, which in non-uniform ferromagnets acquires a
nonlocal tensor structure. In biased ferromagnets, shot noise can become the
dominant contribution to the magnetization noise at low temperatures.
Considering spin spirals as a simple example, we show that the current-induced
noise and damping is significant.
|
0803.2175v1
|
2008-04-23
|
Ion acoustic waves in the plasma with the power-law q-distribution in nonextensive statistics
|
We investigate the dispersion relation and Landau damping of ion acoustic
waves in the collisionless magnetic-field-free plasma if it is described by the
nonextensive q-distributions of Tsallis statistics. We show that the increased
numbers of superthermal particles and low velocity particles can explain the
strengthened and weakened modes of Landau damping, respectively, with the
q-distribution. When the ion temperature is equal to the electron temperature,
the weakly damped waves are found to be the distributions with small values of
q.
|
0804.3732v1
|
2008-07-23
|
Tunneling-induced damping of phase coherence revivals in deep optical lattices
|
We consider phase coherence collapse and revival in deep optical lattices,
and calculate within the Bose-Hubbard model the revival amplitude damping
incurred by a finite tunneling coupling of the lattice wells (after sweeping
from the superfluid to the Mott phase). Deriving scaling laws for the
corresponding decay of first-order coherence revival in terms of filling
factor, final lattice depth, and number of tunneling coupling partners, we
estimate whether revival-damping related to tunneling between sites can be or
even has already been observed in experiment.
|
0807.3627v2
|
2008-07-31
|
Generalized Theory of Landau Damping
|
Collisionless damping of electrical waves in plasma is investigated in the
frame of the classical formulation of the problem. The new principle of
regularization of the singular integral is used. The exact solution of the
corresponding dispersion equation is obtained. The results of calculations lead
to existence of discrete spectrum of frequencies and discrete spectrum of
dispersion curves. Analytical results are in good coincidence with results of
direct mathematical experiments. Key words: Foundations of the theory of
transport processes and statistical physics; Boltzmann physical kinetics;
damping of plasma waves, linear theory of wave`s propagation PACS: 67.55.Fa,
67.55.Hc
|
0807.5007v1
|
2008-08-05
|
Radiation damping, noncommutativity and duality
|
In this work, our main objective is to construct a N=2 supersymmetric
extension of the nonrelativistic $(2+1)$-dimensional model describing the
radiation damping on the noncommutative plane with scalar (electric) and vector
(magnetic) interactions by the N=2 superfield technique. We also introduce a
dual equivalent action to the radiation damping one using the Noether
procedure.
|
0808.0694v2
|
2008-10-06
|
Local existence and exponential growth for a semilinear damped wave equation with dynamic boundary conditions
|
In this paper we consider a multi-dimensional damped semiliear wave equation
with dynamic boundary conditions, related to the Kelvin-Voigt damping. We
firstly prove the local existence by using the Faedo-Galerkin approximations
combined with a contraction mapping theorem. Secondly, the exponential growth
of the energy and the $L^p$ norm of the solution is presented.
|
0810.1013v1
|
2008-11-20
|
An explanation for the pseudogap of high-temperature superconductors based on quantum optics
|
We first explain the pseudogap of high-temperature superconductivity based on
an approach of quantum optics. After introducing a damping factor for the
lifetime $\tau$ of quasiparticles, the superconducting dome is naturally
produced, and the pseudogap is the consequence of pairing with damped
coherence. We derive a new expression of Ginzburg-Landau free energy density,
in which a six-order term due to decoherence damping effect is included.
Without invoking any microscopic pairing mechanism, this approach provides a
simple universal equation of second-order phase transition, which can be
reduced to two well-known empirical scaling equations: the superconducting dome
Presland-Tallon equation, and the normal-state pseudogap crossover temperature
$T^{*}$ line.
|
0811.3262v1
|
2008-12-18
|
Exponential decay for solutions to semilinear damped wave equation
|
This paper is concerned with decay estimate of solutions to the semilinear
wave equation with strong damping in a bounded domain. Introducing an
appropriate Lyaponuv function, we prove that when the damping is linear, we can
find initial data, for which the solution decays exponentially. This result
improves an early one in an article of Gazzola and Squassina.
|
0812.3637v3
|
2009-05-27
|
Difference between penetration and damping lengths in photonic crystal mirrors
|
Different mirror geometries in two-dimensional photonic crystal slabs are
studied with fully-vectorial calculations. We compare their optical properties
and, in particular, we show that, for heterostructure mirrors, the penetration
length associated with the delay induced by distributed reflection is not
correlated to the characteristic damping length of the electromagnetic energy
distribution in the mirror. This unexpected result evidences that the usual
trade-off between short damping lengths and large penetration lengths that is
classically encountered in distributed Bragg reflectors can be overcome with
carefully designed photonic crystal structures.
|
0905.4449v2
|
2009-06-01
|
Exponential Decay Rates for the Damped Korteweg-de Vries Type Equation
|
The exponential decay rate of $L^2-$norm related to the Korteweg-de Vries
equation with localized damping posed on whole real line will be established.
In addition, by using classical arguments we determine the $H^1-$norm of the
solution associated to Korteweg-de Vries equation with damping in whole domain,
can not have a decay property for an arbitrary initial data.
|
0906.0285v2
|
2009-07-02
|
Damping and decoherence of a nanomechanical resonator due to a few two level systems
|
We consider a quantum model of a nanomechanical flexing beam resonator
interacting with a bath comprising a few damped tunneling two level systems
(TLS's). In contrast with a resonator interacting bilinearly with an ohmic free
oscillator bath (modeling clamping loss, for example), the mechanical resonator
damping is amplitude dependent, while the decoherence of quantum superpositions
of mechanical position states depends only weakly on their spatial separation.
|
0907.0431v1
|
2009-07-29
|
High performance single-error-correcting quantum codes for amplitude damping
|
We construct families of high performance quantum amplitude damping codes.
All of our codes are nonadditive and most modestly outperform the best possible
additive codes in terms of encoded dimension. One family is built from
nonlinear error-correcting codes for classical asymmetric channels, with which
we systematically construct quantum amplitude damping codes with parameters
better than any prior construction known for any block length n > 7 except
n=2^r-1. We generalize this construction to employ classical codes over GF(3)
with which we numerically obtain better performing codes up to length 14.
Because the resulting codes are of the codeword stabilized (CWS) type, easy
encoding and decoding circuits are available.
|
0907.5149v1
|
2009-10-12
|
Suppression of Landau damping via electron band gap
|
The pondermotive potential in the X-ray Raman compression can generate an
electron band gap which suppresses the Landau damping. The regime is identified
where a Langmuir wave can be driven without damping in the stimulated Raman
compression. It is shown that the partial wave breaking and the frequency
detuning due to the trapped particles would be greatly reduced.
|
0910.2196v3
|
2009-10-27
|
Rabi type oscillations in damped single 2D-quantum dot
|
We present a quantized model of harmonically confined dot atom with inherent
damping in the presence of a transverse magnetic field. The model leads to a
non hermitian Hamiltonian in real coordinate. We have analytically studied the
effects that damping has on the Rabi type oscillations of the system. The model
explains the decoherence of Rabi oscillation in a Josephson Junction.
|
0910.5184v1
|
2009-12-16
|
Toward a dynamical shift condition for unequal mass black hole binary simulations
|
Moving puncture simulations of black hole binaries rely on a specific gauge
choice that leads to approximately stationary coordinates near each black hole.
Part of the shift condition is a damping parameter, which has to be properly
chosen for stable evolutions. However, a constant damping parameter does not
account for the difference in mass in unequal mass binaries. We introduce a
position dependent shift damping that addresses this problem. Although the
coordinates change, the changes in the extracted gravitational waves are small.
|
0912.3125v1
|
2010-03-08
|
A single-ion nonlinear mechanical oscillator
|
We study the steady state motion of a single trapped ion oscillator driven to
the nonlinear regime. Damping is achieved via Doppler laser-cooling. The ion
motion is found to be well described by the Duffing oscillator model with an
additional nonlinear damping term. We demonstrate a unique ability of tuning
both the linear as well as the nonlinear damping coefficients by controlling
the cooling laser parameters. Our observations open a way for the investigation
of nonlinear dynamics on the quantum-to-classical interface as well as
mechanical noise squeezing in laser-cooling dynamics.
|
1003.1577v1
|
2010-03-09
|
Damping of Nanomechanical Resonators
|
We study the transverse oscillatory modes of nanomechanical silicon nitride
strings under high tensile stress as a function of geometry and mode index m <=
9. Reproducing all observed resonance frequencies with classical elastic theory
we extract the relevant elastic constants. Based on the oscillatory local
strain we successfully predict the observed mode-dependent damping with a
single frequency independent fit parameter. Our model clarifies the role of
tensile stress on damping and hints at the underlying microscopic mechanisms.
|
1003.1868v1
|
2010-03-24
|
Global attractors for strongly damped wave equations with displacement dependent damping and nonlinear source term of critical exponent
|
In this paper the long time behaviour of the solutions of 3-D strongly damped
wave equation is studied. It is shown that the semigroup generated by this
equation possesses a global attractor in H_{0}^{1}(\Omega)\times L_{2}(\Omega)
and then it is proved that this global attractor is a bounded subset of
H^{2}(\Omega)\times H^{2}(\Omega) and also a global attractor in
H^{2}(\Omega)\cap H_{0}^{1}(\Omega)\times H_{0}^{1}(\Omega).
|
1003.4760v3
|
2010-04-12
|
Entanglement properties of optical coherent states under amplitude damping
|
Through concurrence, we characterize the entanglement properties of optical
coherent-state qubits subject to an amplitude damping channel. We investigate
the distillation capabilities of known error correcting codes and obtain upper
bounds on the entanglement depending on the non-orthogonality of the coherent
states and the channel damping parameter. This work provides a first, full
quantitative analysis of these photon-loss codes which are naturally
reminiscent of the standard qubit codes against Pauli errors.
|
1004.1931v2
|
2010-05-20
|
Nonclassical phase-space trajectories for the damped harmonic quantum oscillator
|
The phase-space path-integral approach to the damped harmonic oscillator is
analyzed beyond the Markovian approximation. It is found that pairs of
nonclassical trajectories contribute to the path-integral representation of the
Wigner propagating function. Due to the linearity of the problem, the sum
coordinate of a pair still satisfies the classical equation of motion.
Furthermore, it is shown that the broadening of the Wigner propagating function
of the damped oscillator arises due to the time-nonlocal interaction mediated
by the heat bath.
|
1005.3839v1
|
2010-06-09
|
Self frequency-locking of a chain of oscillators
|
The paper studies the vibrational modes of a slightly damped uniform chain,
with n masses coupled by elastic forces. It will be shown that, for certain
lengths of the chain, that is for certain values of n, the damping of one of
the masses at a specific position in the chain is able to constrain the
vibration of the system to oscillate at a specific frequency. The damped mass
turns out to be a node of the chain, subdividing it in two parts. This node can
be considered as the synchronization element of the two subchains. As a
consequence the oscillating system of n-masses is self-locking to the
synchronized frequency of its subchains.
|
1006.1722v1
|
2010-08-20
|
First principles quasiparticle damping rates in bulk lead
|
First principles calculations of the damping rates (inverse inelastic
lifetimes) of low energy quasiparticles in bulk Pb are presented. Damping rates
are obtained both for excited electrons and holes with energies up to 8 eV on a
set of k vectors throughout the Brillouin zone (BZ). Strong localization
effects in the calculated lifetimes are found. Averaged over the BZ inelastic
lifetimes versus quasiparticle energy are reported as well. In addition, the
effect of the spin-orbit induced splitting in the band structure on the
calculated lifetimes in Pb is investigated.
|
1008.3415v1
|
2010-12-07
|
Turbulence damping as a measure of the flow dimensionality
|
The dimensionality of turbulence in fluid layers determines their properties.
We study electromagnetically driven flows in finite depth fluid layers and show
that eddy viscosity, which appears as a result of three-dimensional motions,
leads to increased bottom damping. The anomaly coefficient, which characterizes
the deviation of damping from the one derived using a quasi-two-dimensional
model, can be used as a measure of the flow dimensionality. Experiments in
turbulent layers show that when the anomaly coefficient becomes high, the
turbulent inverse energy cascade is suppressed. In the opposite limit
turbulence can self-organize into a coherent flow.
|
1012.1371v1
|
2011-03-18
|
Single File Diffusion of particles with long ranged interactions: damping and finite size effects
|
We study the Single File Diffusion (SFD) of a cyclic chain of particles that
cannot cross each other, in a thermal bath, with long ranged interactions, and
arbitrary damping. We present simulations that exhibit new behaviors
specifically associated to systems of small number of particles and to small
damping. In order to understand those results, we present an original analysis
based on the decomposition of the particles motion in the normal modes of the
chain. Our model explains all dynamic regimes observed in our simulations, and
provides convincing estimates of the crossover times between those regimes.
|
1103.3642v1
|
2011-04-21
|
Spin Damping Monopole
|
We present theoretical evidence that a magnetic monopole emerges in dynamic
magnetic systems in the presence of the spin-orbit interaction. The monopole
field is expressed in terms of spin damping associated with magnetization
dynamics. We demonstrate that the observation of this spin damping monopole is
accomplished electrically using Ampere's law for monopole current. Our
discovery suggests the integration of monopoles into electronics, namely,
monopolotronics.
|
1104.4215v2
|
2011-08-16
|
Long time dynamics for forced and weakly damped KdV on the torus
|
The forced and weakly damped Korteweg-de Vries (KdV) equation with periodic
boundary conditions is considered. Starting from $L^2$ and mean-zero initial
data we prove that the solution decomposes into two parts; a linear one which
decays to zero as time goes to infinity and a nonlinear one which always
belongs to a smoother space. As a corollary we prove that all solutions are
attracted by a ball in $H^s$, $s\in(0,1)$, whose radius depends only on $s$,
the $L^2$ norm of the forcing term and the damping parameter. This gives a new
proof for the existence of a smooth global attractor and provides quantitative
information on the size of the attractor set in $H^s$.
|
1108.3358v1
|
2011-10-12
|
Acceleration Control in Nonlinear Vibrating Systems based on Damped Least Squares
|
A discrete time control algorithm using the damped least squares is
introduced for acceleration and energy exchange controls in nonlinear vibrating
systems. It is shown that the damping constant of least squares and sampling
time step of the controller must be inversely related to insure that vanishing
the time step has little effect on the results. The algorithm is illustrated on
two linearly coupled Duffing oscillators near the 1:1 internal resonance. In
particular, it is shown that varying the dissipation ratio of one of the two
oscillators can significantly suppress the nonlinear beat phenomenon.
|
1110.2811v2
|
2011-10-17
|
Normal Mode Expansion of Damped Coupled Oscillators in 3 dimensions
|
In this paper, I aim to study free oscillations of a system of oscillators in
more than one dimensions in the absence of damping. The basic approach lies in
decoupling the motion in the individual perpendicular directions. Once the
equations are decoupled, the existent techniques of Normal mode expansion for
1-dimensional oscillators are used to solve for the equations of motion. I also
study the motion of a driven system of oscillators in higher dimensions in the
presence of a velocity dependent damping force.
|
1110.3773v1
|
2011-10-25
|
Distinguishing mesoscopic quantum superpositions from statistical mixtures in periodically shaken double wells
|
For Bose-Einstein condensates in double wells, N-particle Rabi-like
oscillations often seem to be damped. Far from being a decoherence effect, the
apparent damping can indicate the emergence of quantum superpositions in the
many-particle quantum dynamics. However, in an experiment it would be difficult
to distinguish the apparent damping from decoherence effects. The present paper
suggests using controlled periodic shaking to quasi-instantaneously switch the
sign of an effective Hamiltonian, thus implementing an `echo' technique which
distinguishes quantum superpositions from statistical mixtures. The scheme for
the effective time-reversal is tested by numerically solving the time-dependent
N-particle Schrodinger equation.
|
1110.5444v1
|
2011-11-23
|
Wave Propagation And Landau-Type Damping In Liquids
|
Intermolecular forces are modeled by means of a modified Lennard-Jones
potential, introducing a distance of minimum approach, and the effect of
intermolecular interactions is accounted for with a self consistent field of
the Vlasov type. A Vlasov equation is then written and used to investigate the
propagation of perturbations in a liquid. A dispersion relation is obtained and
an effect of damping, analogous to what is known in plasmas as "Landau
damping", is found to take place.
|
1111.5519v3
|
2011-11-25
|
Radiation Damping for Speeding-up NMR Applications
|
We demonstrate theoretically and numerically how to control the NMR
relaxation rate after application of the standard spin echo technique. Using
radiation damping, we return the nuclear magnetization to its equilibrium state
during a time interval that is negligible compared to the relaxation time. We
obtain an estimate for optimal radiation damping which is consistent with our
numerical simulations.
|
1111.7060v1
|
2011-12-09
|
Perturbed damped pendulum: finding periodic solutions
|
Using the damped pendulum system we introduce the averaging method to study
the periodic solutions of a dynamical system with small perturbation. We
provide sufficient conditions for the existence of periodic solutions with
small amplitude of the non--linear perturbed damped pendulum. The averaging
theory provides a useful means to study dynamical systems, accessible to Master
and PhD students.
|
1112.2129v2
|
2011-12-28
|
The role of damping for the driven anharmonic quantum oscillator
|
For the model of a linearly driven quantum anharmonic oscillator, the role of
damping is investigated. We compare the position of the stable points in phase
space obtained from a classical analysis to the result of a quantum mechanical
analysis. The solution of the full master equation shows that the stable points
behave qualitatively similar to the classical solution but with small
modifications. Both the quantum effects and additional effects of temperature
can be described by renormalizing the damping.
|
1112.6119v1
|
2012-01-03
|
Creating and studying ion acoustic waves in ultracold neutral plasmas
|
We excite ion acoustic waves in ultracold neutral plasmas by imprinting
density modulations during plasma creation. Laser-induced fluorescence is used
to observe the density and velocity perturbations created by the waves. The
effect of expansion of the plasma on the evolution of the wave amplitude is
described by treating the wave action as an adiabatic invariant. After
accounting for this effect, we determine that the waves are weakly damped, but
the damping is significantly faster than expected for Landau damping.
|
1201.0786v1
|
2012-01-05
|
Damped bead on a rotating circular hoop - a bifurcation zoo
|
The evergreen problem of a bead on a rotating hoop shows a multitude of
bifurcations when the bead moves with friction. This motion is studied for
different values of the damping coefficient and rotational speeds of the hoop.
Phase portraits and trajectories corresponding to all different modes of motion
of the bead are presented. They illustrate the rich dynamics associated with
this simple system. For some range of values of the damping coefficient and
rotational speeds of the hoop, linear stability analysis of the equilibrium
points is inadequate to classify their nature. A technique involving
transformation of coordinates and order of magnitude arguments is presented to
examine such cases. This may provide a general framework to investigate other
complex systems.
|
1201.1218v1
|
2012-02-24
|
Small data global existence for the semilinear wave equation with space-time dependent damping
|
In this paper we consider the critical exponent problem for the semilinear
wave equation with space-time dependent damping. When the damping is effective,
it is expected that the critical exponent agrees with that of only space
dependent coefficient case. We shall prove that there exists a unique global
solution for small data if the power of nonlinearity is larger than the
expected exponent. Moreover, we do not assume that the data are compactly
supported. However, it is still open whether there exists a blow-up solution if
the power of nonlinearity is smaller than the expected exponent.
|
1202.5379v1
|
2012-03-11
|
Magnetic damping of a carbon nanotube NEMS resonator
|
A suspended, doubly clamped single wall carbon nanotube is characterized at
cryogenic temperatures. We observe specific switching effects in dc-current
spectroscopy of the embedded quantum dot. These have been identified previously
as nano-electromechanical self-excitation of the system, where positive
feedback from single electron tunneling drives mechanical motion. A magnetic
field suppresses this effect, by providing an additional damping mechanism.
This is modeled by eddy current damping, and confirmed by measuring the
resonance quality factor of the rf-driven nano-electromechanical resonator in
an increasing magnetic field.
|
1203.2319v2
|
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