publicationDate stringlengths 1 2.79k | title stringlengths 1 36.5k ⌀ | abstract stringlengths 1 37.3k ⌀ | id stringlengths 9 47 |
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2006-07-15 | Damping and excitation variations of the solar acoustic modes using LOWL observations | We have used observations made with the helioseismic instrument LOWL
collected over $\sim$ 6 years to carry out an independent study of the
variations of the p-mode damping and excitation rates with solar activity. We
observe significant variations in the mode height, mode width and mode velocity
power over a wide rang... | 0607346v1 |
2006-09-01 | A line profile analysis of the pulsating red giant star epsilon Ophiuchi (G9.5III) | So far, solar-like oscillations have been studied using radial velocity
and/or light curve variations, which reveal frequencies of the oscillation
modes. Line-profile variations, however, are also a valuable diagnostic to
characterise radial and non-radial oscillations, including frequencies,
amplitudes, the spherical ... | 0609043v1 |
2006-10-11 | Determining the neutron star equation of state using the narrow-band gravitational wave detector Schenberg | We briefly review the properties of quasi-normal modes of neutron stars and
black holes. We analyse the consequences of a possible detection of such modes
via the gravitational waves associated with them, especially addressing our
study to the Brazilian spherical antenna, on which a possible detection would
occur at 3.... | 0610335v1 |
2006-12-14 | Three dimensional numerical simulations of acoustic wave field in the upper convection zone of the Sun | Results of numerical 3D simulations of propagation of acoustic waves inside
the Sun are presented. A linear 3D code which utilizes realistic OPAL equation
of state was developed by authors. Modified convectively stable standard solar
model with smoothly joined chromosphere was used as a background model. High
order dis... | 0612364v1 |
2006-12-15 | Damp Mergers: Recent Gaseous Mergers without Significant Globular Cluster Formation? | Here we test the idea that new globular clusters (GCs) are formed in the same
gaseous ("wet") mergers or interactions that give rise to the young stellar
populations seen in the central regions of many early-type galaxies. We compare
mean GC colors with the age of the central galaxy starburst. The red GC
subpopulation ... | 0612415v1 |
2006-12-21 | Accretion of Terrestrial Planets from Oligarchs in a Turbulent Disk | We have investigated the final accretion stage of terrestrial planets from
Mars-mass protoplanets that formed through oligarchic growth in a disk
comparable to the minimum mass solar nebula (MMSN), through N-body simulation
including random torques exerted by disk turbulence due to
Magneto-Rotational-Instability. For t... | 0612619v1 |
2007-01-18 | Models of the Collisional Damping Scenario for Ice Giant Planets and Kuiper Belt Formatio | Chiang et al. 2006, hereafter C06 have recently proposed that the observed
structure of the Kuiper belt could be the result of a dynamical instability of
a system of ~5 primordial ice giant planets in the outer Solar System.
According to this scenario, before the instability occurred, these giants were
growing in a hig... | 0701544v1 |
2007-02-05 | Ion Charge States in the Fast Solar Wind: New Data Analysis and Theoretical Refinements | We present a further investigation into the increased ionization observed in
element charge states in the fast solar wind compared to its coronal hole
source regions. Once ions begin to be perpendicularly heated by ion cyclotron
waves and execute large gyro-orbits, density gradients in the flow can excite
lower hybrid ... | 0702131v1 |
1995-10-11 | Multiple Transitions to Chaos in a Damped Parametrically Forced Pendulum | We study bifurcations associated with stability of the lowest stationary
point (SP) of a damped parametrically forced pendulum by varying $\omega_0$
(the natural frequency of the pendulum) and $A$ (the amplitude of the external
driving force). As $A$ is increased, the SP will restabilize after its
instability, destabil... | 9510003v1 |
1996-03-04 | Period Doublings in Coupled Parametrically Forced Damped Pendulums | We study period doublings in $N$ $(N=2,3,4, \dots)$ coupled parametrically
forced damped pendulums by varying $A$ (the amplitude of the external driving
force) and $c$ (the strength of coupling). With increasing $A$, the stationary
point undergoes multiple period-doubling transitions to chaos. We first
investigate the ... | 9603002v1 |
1996-12-05 | Fractal Basins of Attraction Associated with a Damped Newton's Method | An intriguing and unexpected result for students learning numerical analysis
is that Newton's method, applied to the simple polynomial z^3 - 1 = 0 in the
complex plane, leads to intricately interwoven basins of attraction of the
roots. As an example of an interesting open question that may help to stimulate
student int... | 9612010v1 |
1999-01-28 | Intrinsically localized chaos in discrete nonlinear extended systems | The phenomenon of intrinsic localization in discrete nonlinear extended
systems, i.e. the (generic) existence of discrete breathers, is shown to be not
restricted to periodic solutions but it also extends to more complex (chaotic)
dynamical behaviour. We illustrate this with two different forced and damped
systems exhi... | 9901030v1 |
1995-03-27 | Dynamics of a Strongly Damped Two-Level System: Beyond the DBGA | Dynamics of a dissipative two-level system is studied using quantum
relaxation theory. This calculation for the first time goes beyond the commonly
used dilute bounce gas approximation (DBGA), even for strong damping. The new
results obtained here deviate from the DBGA results at low temperatures,
however, the DBGA for... | 9503133v1 |
1995-05-23 | The phase-dependent linear conductance of a superconducting quantum point contact | The exact expression for the phase-dependent linear conductance of a weakly
damped superconducting quantum point contact is obtained. The calculation is
performed by summing up the complete perturbative series in the coupling
between the electrodes. The failure of any finite order perturbative expansion
in the limit of... | 9505102v1 |
1996-02-27 | Quasiparticle properties of a coupled quantum wire electron-phonon system | We study leading-order many-body effects of longitudinal optical (LO) phonons
on electronic properties of one-dimensional quantum wire systems. We calculate
the quasiparticle properties of a weakly polar one dimensional electron gas in
the presence of both electron-phonon and electron-electron interactions. The
leading... | 9602143v1 |
1996-02-29 | Dynamical response of a one dimensional quantum wire electron system | We provide a self-contained theoretical analysis of the dynamical response of
a one dimensional electron system, as confined in a semiconductor quantum wire,
within the random phase approximation. We carry out a detailed comparison with
the corresponding two and three dimensional situations, and discuss the
peculiariti... | 9602157v1 |
1996-08-24 | New Universality Class at the Superconductor--Insulator Transition | We study dynamic properties of thin films near the superconductor - insulator
transition. We formulate the problem in a phase representation. The key new
feature of our model is the assumption of a {\it local} ohmic dissipative
mechanism. Coarse graining leads to a Ginzburg-Landau description, with
non-ohmic dynamics f... | 9608115v1 |
1996-10-07 | Supersymmetric Fokker-Planck strict isospectrality | I report a study of the nonstationary one-dimensional Fokker-Planck solutions
by means of the strictly isospectral method of supesymmetric quantum mechanics.
The main conclusion is that this technique can lead to a space-dependent
(modulational) damping of the spatial part of the nonstationary Fokker-Planck
solutions, ... | 9610049v2 |
1997-04-03 | Quasiparticle Many-Body Dynamics of Highly Correlated Electronic Systems | The self-consistent theory of the correlation effects in Highly Correlated
Systems(HCS) is presented. The novel Irreducible Green's Functions(IGF) method
is discused in detail for the Hubbard model and random Hubbard model. The
interpolative solution for the quasiparticle spectrum, which is valid for both
the atomic an... | 9704028v1 |
1997-12-17 | Detecting flux creep in superconducting YBCO thin films via damping of the oscillations of a levitating permanent magnet | The damping of the oscillations of a small permanent magnet (spherical shape,
radius 0.1 mm) levitating between two parallel epitaxial YBCO films is measured
as a function of oscillation amplitude and temperature. At small amplitudes the
dissipation is found to be orders of magnitude lower than in bulk YBCO,
Q-factors ... | 9712199v1 |
1998-02-06 | Spin polaron damping in the spin-fermion model for cuprate superconductors | A self-consistent, spin rotational invariant Green's function procedure has
been developed to calculate the spectral function of carrier excitations in the
spin-fermion model for the CuO2 plane. We start from the mean field description
of a spin polaron in the Mori-Zwanzig projection method. In order to determine
the s... | 9802074v1 |
1998-02-24 | Resonant steps and spatiotemporal dynamics in the damped dc-driven Frenkel-Kontorova chain | Kink dynamics of the damped Frenkel-Kontorova (discrete sine-Gordon) chain
driven by a constant external force are investigated. Resonant steplike
transitions of the average velocity occur due to the competitions between the
moving kinks and their radiated phasonlike modes. A mean-field consideration is
introduced to g... | 9802251v1 |
1998-05-09 | The resonance peak in cuprate superconductors | We pursue the consequences of a theory in which the resonance peak observed
in inelastic neutron scattering (INS) experiments on underdoped and optimally
doped YBa$_2$Cu$_3$O$_{6+x}$ compounds arises from a spin-wave excitation. We
find that it is heavily damped, and thus almost not observable, in the normal
state, but... | 9805107v1 |
1998-05-22 | On the driven Frenkel-Kontorova model: I. Uniform sliding states and dynamical domains of different particle densities | The dynamical behavior of a harmonic chain in a spatially periodic potential
(Frenkel-Kontorova model, discrete sine-Gordon equation) under the influence of
an external force and a velocity proportional damping is investigated. We do
this at zero temperature for long chains in a regime where inertia and damping
as well... | 9805287v1 |
1999-01-29 | Acoustic radiation controls friction: Evidence from a spring-block experiment | Brittle failures of materials and earthquakes generate acoustic/seismic waves
which lead to radiation damping feedbacks that should be introduced in the
dynamical equations of crack motion. We present direct experimental evidence of
the importance of this feedback on the acoustic noise spectrum of
well-controlled sprin... | 9901350v2 |
1999-03-02 | d_{x^2-y^2}-Wave Pairing Fluctuations and Pseudo Spin Gap in Two-Dimensional Electron Systems | Pseudogap phenomena of high-T_c cuprates are examined. In terms of AFM
(antiferromagnetic) and dSC (d_{x^2-y^2}-wave superconducting) auxiliary fields
introduced to integrate out the fermions, the effective action for 2D electron
systems with AFM and dSC fluctuations is considered. By the self-consistent
renormalizatio... | 9903030v2 |
1999-03-11 | Thermally activated escape rates of uniaxial spin systems with transverse field | Classical escape rates of uniaxial spin systems are characterized by a
prefactor differing from and much smaller than that of the particle problem,
since the maximum of the spin energy is attained everywhere on the line of
constant latitude: theta=const, 0 =< phi =< 2*pi. If a transverse field is
applied, a saddle poin... | 9903192v2 |
1999-04-19 | Numerical analysis of the dissipative two-state system with the density-matrix Hilbert-space-reduction algorithm | Ground state of the dissipative two-state system is investigated by means of
the Lanczos diagonalization method. We adopted the Hilbert-space-reduction
scheme proposed by Zhang, Jeckelmann and White so as to reduce the overwhelming
reservoir Hilbert space to being tractable in computers. Both the
implementation of the ... | 9904260v1 |
1999-05-02 | Finite Temperature Time-Dependent Effective Theory For The Goldstone Field In A BCS-Type Superfluid | We extend to finite temperature the time-dependent effective theory for the
Goldstone field (the phase of the pair field) $ \theta $ which is appropriate
for a superfluid containing one species of fermions with s-wave interactions,
described by the BCS Lagrangian. We show that, when Landau damping is
neglected, the eff... | 9905008v2 |
1999-06-29 | Simulation of I-V Hysteresis Branches in An Intrinsic Stack of Josephson Junctions in High $T_c$ Superconductors | I-V characteristics of the high T$_c$ superconductor
Bi$_2$Sr$_2$Ca$_1$C$_2$O$_8$ shows a strong hysteresis, producing many
branches. The origin of hysteresis jumps is studied by use of the model of
multi-layered Josephson junctions proposed by one of the authors (T. K.). The
charging effect at superconducting layers p... | 9906422v1 |
1999-07-05 | The interplay between flattening and damping of single particle spectra in strongly correlated Fermi systems | The self-consistent theory of the fermion condensation, a specific phase
transition which results in a rearrangement of the single particle degrees of
freedom in strongly correlated Fermi systems is developed. Beyond the phase
transition point, the single particle spectra are shown to be flat. The
interplay between the... | 9907061v1 |
1999-10-19 | Zener transitions between dissipative Bloch bands. II: Current Response at Finite Temperature | We extend, to include the effects of finite temperature, our earlier study of
the interband dynamics of electrons with Markoffian dephasing under the
influence of uniform static electric fields. We use a simple two-band
tight-binding model and study the electric current response as a function of
field strength and the ... | 9910290v1 |
1999-11-02 | Shifts and widths of collective excitations in trapped Bose gases by the dielectric formalism | We present predictions for the temperature dependent shifts and damping
rates. They are obtained by applying the dielectric formalism to a simple model
of a trapped Bose gas. Within the framework of the model we use lowest order
perturbation theory to determine the first order correction to the results of
Hartree-Fock-... | 9911018v1 |
2000-06-13 | Characteristic features of anharmonic effects in the lattice dynamics of fcc metals | The dispersion in the entire Brillouin zone and the temperature dependence
(right up to the melting temperature) of the anharmonic frequency shift and
phonon damping in a number of fcc metals is investigated on the basis of
microscopic calculations. It is found that the anharmonic effects depend
sharply on the wave vec... | 0006205v1 |
2000-06-20 | Collisional damping of the collective oscillations of a trapped Fermi gas | We consider a Fermi gas confined by a harmonic trapping potential and we
highlight the role of the Fermi-Dirac statistics by studying frequency and
damping of collective oscillations of quadrupole type in the framework of the
quantum Boltzmann equation, in which statistical corrections are taken into
account in the col... | 0006305v2 |
2000-06-21 | Resonances in the dynamics of $φ^4$ kinks perturbed by ac forces | We study the dynamics of $\phi^4$ kinks perturbed by an ac force, both with
and without damping. We address this issue by using a collective coordinate
theory, which allows us to reduce the problem to the dynamics of the kink
center and width. We carry out a careful analysis of the corresponding ordinary
differential e... | 0006313v1 |
2000-07-11 | Quantum phase transitions in d-wave superconductors | Motivated by the strong, low temperature damping of nodal quasiparticles
observed in some cuprate superconductors, we study quantum phase transitions in
d_{x^2-y^2} superconductors with a spin-singlet, zero momentum, fermion
bilinear order parameter. We present a complete, group-theoretic classification
of such transit... | 0007170v3 |
2000-07-12 | Frequencies and Damping rates of a 2D Deformed Trapped Bose gas above the Critical Temperature | We derive the equation of motion for the velocity fluctuations of a 2D
deformed trapped Bose gas above the critical temperature in the hydrodynamical
regime. From this equation, we calculate the eigenfrequencies for a few
low-lying excitation modes. Using the method of averages, we derive a
dispersion relation in a def... | 0007210v2 |
2000-09-01 | The Broad Brillouin Doublet and CP of Ktao_3 : Second Sound vs. Two-Phonon Difference Scattering | Low-T Brillouin spectra of the incipient ferroelectric KTaO3 exhibit a broad
central peak (CP), and additional Brillouin doublets (BD), that can both be
related to phonon-density fluctuations. On the basis of new high-resolution
neutron data obtained of low-lying phonon branches, we analysed the
phonon-kinetics mechani... | 0009011v1 |
2000-09-21 | Landau-Khalatnikov two-fluid hydrodynamics of a trapped Bose gas | Starting from the quantum kinetic equation for the non-condensate atoms and
the generalized Gross-Pitaevskii equation for the condensate, we derive the
two-fluid hydrodynamic equations of a trapped Bose gas at finite temperatures.
We follow the standard Chapman-Enskog procedure, starting from a solution of
the kinetic ... | 0009333v1 |
2000-12-29 | Finite Temperature Time-Dependent Effective Theory for the Phase Field in two-dimensional d-wave Neutral Superconductor | We derive finite temperature time-dependent effective actions for the phase
of the pairing field, which are appropriate for a 2D electron system with both
non-retarded d- and s-wave attraction. As for s-wave pairing the d-wave
effective action contains terms with Landau damping, but their structure
appears to be differ... | 0012511v4 |
2001-01-23 | Ginzburg-Landau theory for the time-dependent phase field in a two-dimensional d-wave superconductor | We derive a finite temperature time-dependent effective theory for the phase
$\theta$ of the pairing field, which is appropriate for a 2D conducting
electron system with non-retarded d-wave attraction. As for s-wave pairing the
effective action contains terms with Landau damping, but their structure
appears to be diffe... | 0101353v1 |
2001-06-05 | Damping and frequency shift in the oscillations of two colliding Bose-Einstein condensates | We have investigated the center-of-mass oscillations of a Rb87 Bose-Einstein
condensate in an elongated magneto-static trap. We start from a trapped
condensate and we transfer part of the atoms to another trapped level, by
applying a radio-frequency pulse. The new condensate is produced far from its
equilibrium positio... | 0106072v1 |
2001-07-12 | Ferromagnetism in the Hubbard model | We investigate the possibility and stability of bandferromagnetism in the
single-band Hubbard model. This model poses a highly non-trivial many-body
problem the general solution of which has not been found up to now.
Approximations are still unavoidable. Starting from a simple two-pole ansatz
for the spectral density o... | 0107255v1 |
2001-09-10 | Finite temperature theory of the scissors mode in a Bose gas using the moment method | We use a generalized Gross-Pitaevskii equation for the condensate and a
semi-classical kinetic equation for the noncondensate atoms to discuss the
scissors mode in a trapped Bose-condensed gas at finite temperatures. Both
equations include the effect of $C_{12}$ collisions between the condensate and
noncondensate atoms... | 0109149v1 |
2002-01-24 | Dynamic light scattering from colloidal fractal monolayers | We address experimentally the problem of how the structure of a surface
monolayer determines the visco-elasticity of the interface. Optical microscopy
and surface quasi--elastic light scattering have been used to characterize
aggregation of CaCO$_3$ particles at the air--water interface. The structures
formed by cluste... | 0201438v1 |
2002-08-08 | Excitation and damping of collective modes of a Bose-Einstein condensate in a one-dimensional lattice | The mode structure of a Bose-Einstein condensate non-adiabatically loaded
into a one-dimensional optical lattice is studied by analyzing the visibility
of the interference pattern as well as the radial profile of the condensate
after a time-of-flight. A simple model is proposed that predicts the short-time
decrease of ... | 0208162v1 |
2002-08-12 | Spectral Properties of the Generalized Spin-Fermion Models | In order to account for competition and interplay of localized and itinerant
magnetic behaviour in correlated many body systems with complex spectra the
various types of spin-fermion models have been considered in the context of the
Irreducible Green's Functions (IGF) approach. Examples are generalized d-f
model and Ko... | 0208227v1 |
2002-08-13 | Itinerant Antiferromagnetism of Correlated Lattice Fermions | The problem of finding of the ferromagnetic and antiferromagnetic "symmetry
broken" solutions of the correlated lattice fermion models beyond the
mean-field approximation has been investigated. The calculation of the
quasiparticle excitation spectra with damping for the single- and multi-orbital
Hubbard model has been ... | 0208242v1 |
2003-01-21 | Zero temperature damping of Bose-Einstein condensate oscillations by vortex-antivortex pair creation | We investigate vortex-antivortex pair creation in a supersonically expanding
and contracting quasi-2D Bose-Einstein condensate at zero temperature. For
sufficiently large amplitude condensate oscillations, pair production provides
the leading dissipation mechanism. The condensate oscillations decay in a
nonexponential ... | 0301397v3 |
2003-02-10 | Damped orbital excitations in the titanates | A possible mechanism for the removal of the orbital degeneracy in RTiO3
(where R=La, Y, ...) is considered. The calculation is based on the
Kugel-Khomskii Hamiltonian for electrons residing in the t2g orbitals of the Ti
ions, and uses a self-consistent pe rturbation expansion in the interaction
between the orbital and ... | 0302182v1 |
2003-03-20 | Energies and damping rates of elementary excitations in spin-1 Bose-Einstein condensed gases | Finite temperature Green's function technique is used to calculate the
energies and damping rates of elementary excitations of the homogeneous,
dilute, spin-1 Bose gases below the Bose-Einstein condensation temperature both
in the density and spin channels. For this purpose the self-consistent
dynamical Hartree-Fock mo... | 0303424v3 |
2003-04-17 | Non-Fermi liquid behavior from two-dimensional antiferromagnetic fluctuations: a renormalization-group and large-N analysis | We analyze the Hertz-Moriya-Millis theory of an antiferromagnetic quantum
critical point, in the marginal case of two dimensions (d=2,z=2). Up to
next-to-leading order in the number of components (N) of the field, we find
that logarithmic corrections do not lead to an enhancement of the Landau
damping. This is in agree... | 0304415v1 |
2003-05-21 | The path-coalescence transition and its applications | We analyse the motion of a system of particles subjected a random force
fluctuating in both space and time, and experiencing viscous damping. When the
damping exceeds a certain threshold, the system undergoes a phase transition:
the particle trajectories coalesce. We analyse this transition by mapping it to
a Kramers p... | 0305491v2 |
2003-05-21 | Magnetoresistive response of a high mobility 2DES under electromagnetic wave excitation | Oscillations of the resistance observed under electromagnetic wave excitation
in the high mobility GaAs/AlGaAs 2DES are examined as a function of the
radiation frequency and the power, utilizing an empirical lineshape based on
exponentially damped sinusoids. The fit-analysis indicates the resistance
oscillation frequen... | 0305507v2 |
2003-06-16 | Infrared Spectroscopy of Quantum Crossbars | Infrared (IR) spectroscopy can be used as an important and effective tool for
probing periodic networks of quantum wires or nanotubes (quantum crossbars,
QCB) at finite frequencies far from the Luttinger liquid fixed point. Plasmon
excitations in QCB may be involved in resonance diffraction of incident
electromagnetic ... | 0306409v1 |
2003-06-19 | Superradiant light scattering from a moving Bose-Einstein condensate | We investigate the interaction of a moving BEC with a far detuned laser beam.
Superradiant Rayleigh scattering arises from the spontaneous formation of a
matter-wave grating due to the interference of two wavepackets with different
momenta. The system is described by the CARL-BEC model which is a
generalization of the ... | 0306500v2 |
2003-07-25 | Finite temperature excitations of a trapped Bose-Fermi mixture | We present a detailed study of the low-lying collective excitations of a
spherically trapped Bose-Fermi mixture at finite temperature in the
collisionless regime. The excitation frequencies of the condensate are
calculated self-consistently using the static Hartree-Fock-Bogoliubov theory
within the Popov approximation.... | 0307638v1 |
2003-09-18 | Memory-function approach to the normal-state optical properties of the Bechgaard salt (TMTSF)_2PF_6 | The gauge invariant, two-component optical conductivity model, with a
correlation gap structure related to the umklapp scattering processes, is
applied to the quasi-one-dimensional electronic systems and compared to the
recent measurements on the Bechgaard salt (TMTSF)_2PF_6. The optical response
of both the insulating... | 0309419v1 |
2003-10-03 | Effects of electrostatic fields and Casimir force on cantilever vibrations | The effect of an external bias voltage and fluctuating electromagnetic fields
on both the fundamental frequency and damping of cantilever vibrations is
considered. An external voltage induces surface charges causing
cantilever-sample electrostatic attraction. A similar effect arises from
charged defects in dielectrics ... | 0310081v1 |
2003-10-07 | Precessional switching of thin nanomagnets: analytical study | We study analytically the precessional switching of the magnetization of a
thin macrospin. We analyze its response when subjected to an external field
along its in-plane hard axis. We derive the exact trajectories of the
magnetization. The switching versus non switching behavior is delimited by a
bifurcation trajectory... | 0310147v1 |
2003-11-27 | Temperature dependent Bogoliubov approximation in the classical fields approach to weakly interacting Bose gas | A classical fields approximation to the finite temperature microcanonical
thermodynamics of weakly interacting Bose gas is applied to the idealized case
of atoms confined in a box with periodic boundary conditions. We analyze in
some detail the microcanonical temperature in the model. We also analyze the
spectral prope... | 0311622v1 |
2003-12-29 | Plasmon attenuation and optical conductivity of a two-dimensional electron gas | In a ballistic two-dimensional electron gas, the Landau damping does not lead
to plasmon attenuation in a broad interval of wave vectors q << k_F. Similarly,
it does not contribute to the optical conductivity \sigma (\omega, q) in a wide
domain of its arguments, E_F > \omega > qv_F, where E_F, k_F and v_F are,
respecti... | 0312684v3 |
2004-03-05 | Mode-coupling theory and molecular dynamics simulation for heat conduction in a chain with transverse motions | We study heat conduction in a one-dimensional chain of particles with
longitudinal as well as transverse motions. The particles are connected by
two-dimensional harmonic springs together with bending angle interactions. The
problem is analyzed by mode-coupling theory and compared with molecular
dynamics. We find very g... | 0403162v1 |
2004-03-21 | Evidence for Superfluidity in a Resonantly Interacting Fermi Gas | We observe collective oscillations of a trapped, degenerate Fermi gas of
$^6$Li atoms at a magnetic field just above a Feshbach resonance, where the
two-body physics does not support a bound state. The gas exhibits a radial
breathing mode at a frequency of 2837(05) Hz, in excellent agreement with the
frequency of $\nu_... | 0403540v2 |
2004-03-22 | Parametric Driving of Dark Solitons in Atomic Bose-Einstein Condensates | A dark soliton oscillating in an elongated harmonically-confined atomic
Bose-Einstein condensate continuously exchanges energy with the sound field.
Periodic optical `paddles' are employed to controllably enhance the sound
density and transfer energy to the soliton, analogous to parametric driving. In
the absence of da... | 0403566v2 |
2004-04-09 | Network-Induced Oscillatory Behavior in Material Flow Networks | Network theory is rapidly changing our understanding of complex systems, but
the relevance of topological features for the dynamic behavior of metabolic
networks, food webs, production systems, information networks, or cascade
failures of power grids remains to be explored. Based on a simple model of
supply networks, w... | 0404226v1 |
2004-04-28 | Dynamics of the Electro-Reflective Response of TaS3 | We have observed a large (~1%) change in infrared reflectance of the
charge-density-wave (CDW) conductor, orthorhombic TaS3, when its CDW is
depinned. The change is concentrated near one current contact. Assuming that
the change in reflectance is proportional to the degree of CDW polarization, we
have studied the dynam... | 0404690v1 |
2004-05-06 | Damping of the de Haas-van Alphen oscillations in the superconducting state of MgB_2 | The de Haas-van Alphen (dHvA) signal arising from orbits on the $\pi$ Fermi
surface sheet of the two-gap superconductor MgB$_2$ has been observed in the
vortex state below $H_{c2}$. An extra attenuation of the dHvA signal, beyond
those effects described in the conventional Lifshitz-Kosevich expression, is
seen due to t... | 0405120v1 |
2004-05-26 | Magnetic droplets in a metal close to a ferromagnetic quantum critical point | Using analytical and path integral Monte Carlo methods, we study the
susceptibility $\chi_{dc}(T)$ of a spin-S impurity with XY rotational symmetry
embedded in a metal. Close to a ferromagnetic quantum critical point, the
impurity polarizes conduction electrons in its vicinity and forms a large
magnetic droplet with mo... | 0405618v2 |
2004-06-29 | Pairing gaps in atomic gases at the BCS-BEC crossover | Strong evidence for pairing and superfluidity has recently been found in
atomic Fermi gases at the BCS-BEC crossover both in collective modes and RF
excitation energies. It is argued that the scale for the effective pairing gaps
measured in RF experiments is set by the lowest quasiparticle in-gap excitation
energies. T... | 0406714v3 |
2004-08-26 | Decoherence of Rabi oscillations in a single quantum dot | We develop a realistic model of Rabi oscillations in a quantum-dot
photodiode. Based in a multi-exciton density matrix formulation we show that
for short pulses the two-level models fails and higher levels should be taken
into account. This affects some of the experimental conclusions, such as the
inferred efficiency o... | 0408570v2 |
2004-08-28 | Breakdown of Hydrodynamics in the Radial Breathing Mode of a Strongly-Interacting Fermi Gas | We measure the magnetic field dependence of the frequency and damping time
for the radial breathing mode of an optically trapped, Fermi gas of $^6$Li
atoms near a Feshbach resonance. The measurements address the apparent
discrepancy between the results of Kinast et al., [Phys. Rev. Lett. {\bf 92},
150402 (2004)] and th... | 0408634v2 |
2004-10-01 | Magnetic Properties of Cuprate Perovskites | The magnetic susceptibility of underdoped yttrium and lanthanum cuprates is
interpreted based on the self-consistent solution of the t-J model of a Cu-O
plane. The calculations reproduce correctly the frequency dependencies of the
susceptibility in YBa2Cu3O_{7-y} and La_{2-x}Sr_xCuO4 attributing their
dissimilarity to ... | 0410009v1 |
2004-11-12 | Microwave induced resistance oscillations on a high-mobility 2DEG: absorption/reflection and temperature damping experiments | In this work we address experimentally a number of unresolved issues related
to microwave induced resistance oscillations (MIRO) and the zero-resistance
states observed recently on very high-mobility 2D electron gases in GaAs/AlGaAs
heterostructures. In particular, we examine electrodynamic effects via
reflection/absor... | 0411338v1 |
2004-11-17 | Path integral derivation of Bloch-Redfield equations for a qubit weakly coupled to a heat bath: Application to nonadiabatic transitions | Quantum information processing has greatly increased interest in the
phenomenon of environmentally-induced decoherence. The spin boson model is
widely used to study the interaction between a spin-modelling a quantum
particle moving in a double well potential-and its environment-modelled by a
heat bath of harmonic oscil... | 0411443v1 |
2004-11-24 | Josephson tunnel junctions with nonlinear damping for RSFQ-qubit circuit applications | We demonstrate that shunting of Superconductor-Insulator-Superconductor
Josephson junctions by Superconductor-Insulator-Normal metal (S-I-N) structures
having pronounced non-linear I-V characteristics can remarkably modify the
Josephson dynamics. In the regime of Josephson generation the phase behaves as
an overdamped ... | 0411607v1 |
2004-12-01 | Reply to Millis et al. on "A Tale of Two Theories: Quantum Griffiths Effects in Metallic Systems" | In a recent paper (cond-mat/0411197) we showed the equivalence of two
seemingly contradictory theories on Griffiths-McCoy singularities (GMS) in
metallic antiferromagnets close to a quantum critical point (QCP). In a recent
comment, Millis {\it et al.} (cond-mat/0411738) argue that in heavy-fermion
materials the electr... | 0412020v2 |
2005-01-04 | On continuum modeling of sputter erosion under normal incidence: interplay between nonlocality and nonlinearity | Under specific experimental circumstances, sputter erosion on semiconductor
materials exhibits highly ordered hexagonal dot-like nanostructures. In a
recent attempt to theoretically understand this pattern forming process, Facsko
et al. [Phys. Rev. B 69, 153412 (2004)] suggested a nonlocal, damped
Kuramoto-Sivashinsky ... | 0501049v2 |
2005-01-18 | Incommensurate spin dynamics in underdoped cuprate perovskites | The incommensurate magnetic response observed in normal-state cuprate
perovskites is interpreted based on the projection operator formalism and the
t-J model of Cu-O planes. In agreement with experiment the calculated
dispersion of maxima in the susceptibility has the shape of two parabolas with
upward and downward bra... | 0501418v1 |
2005-02-21 | Velocity dependence of atomic-scale friction: a comparative study of the one- and two-dimensional Tomlinson model | We present a comparative analysis of the velocity dependence of atomic-scale
friction for the Tomlinson model, at zero and finite temperatures, in 1D and
2D, and for different values of the damping. Combining analytical arguments
with numerical simulations, we show that an appreciable velocity dependence of
the kinetic... | 0502496v1 |
2005-03-12 | Collective Oscillations of Strongly Correlated One-Dimensional Bosons on a Lattice | We study the dipole oscillations of strongly correlated 1D bosons, in the
hard-core limit, on a lattice, by an exact numerical approach. We show that far
from the regime where a Mott insulator appears in the system, damping is always
present and increases for larger initial displacements of the trap, causing
dramatic c... | 0503302v2 |
2005-04-28 | Coherence properties of bulk matter | We prove a theorem, using the density functional approach and relying on a
classical result by Lieb and Simon on Thomas-Fermi model, showing that in the
thermodynamic limit bulk matter is at most semiclassical and coherence
preserving. The connection between quantum fluid dynamics and density
functional theory in the f... | 0504768v3 |
2005-05-19 | Harmonic Content of Strain-induced Potential Modulation in Unidirectional Lateral Superlattices | Detailed analysis of the commensurability oscillation (CO) has been performed
on unidirectional lateral superlattices with periods ranging from a=92 to 184
nm. Fourier analysis reveals the second (and the third) harmonics along with
the fundamental oscillation for a>=138 nm (184 nm) at low-enough temperature,
evincing ... | 0505479v1 |
2005-06-14 | Lifetime of the first and second collective excitations in metallic nanoparticles | We determine the lifetime of the surface plasmon in metallic nanoparticles
under various conditions, concentrating on the Landau damping, which is the
dominant mechanism for intermediate-size particles. Besides the main
contribution to the lifetime, which smoothly increases with the size of the
particle, our semiclassi... | 0506320v2 |
2005-07-27 | Dynamics of a nanomechanical resonator coupled to a superconducting single-electron transistor | We present an analysis of the dynamics of a nanomechanical resonator coupled
to a superconducting single electron transistor (SSET) in the vicinity of the
Josephson quasiparticle (JQP) and double Josephson quasiparticle (DJQP)
resonances. For weak coupling and wide separation of dynamical timescales, we
find that for e... | 0507645v1 |
2005-08-01 | Unexpected Effect of Internal Degrees of Freedom on Transverse Phonons in Supercooled Liquids | We show experimentally that in a supercooled liquid composed of molecules
with internal degrees of freedom the internal modes contribute to the frequency
dependent shear viscosity and damping of transverse phonons, which results in
an additional broadening of the transverse Brillouin lines. Earlier, only the
effect of ... | 0508046v1 |
2005-08-05 | Damping of vortex waves in a superfluid | The damping of vortex cyclotron modes is investigated within a generalized
quantum theory of vortex waves. Similarly to the case of Kelvin modes, the
friction coefficient turns out to be essentially unchanged under such
oscillations, but it is shown to be affected by appreciable memory corrections.
On the other hand, t... | 0508167v1 |
2005-08-08 | Collective excitations of low density fermion-boson quantum-liquid mixtures | We investigate the collective excitations of a low temperature dilute gas
mixture that consists of a Bose-Einstein condensate and a Fermi-gas that is a
normal (i.e. non-superfluid) Fermi-liquid. We find that the BEC-mediated
fermion-fermion interactions, as a consequence of retardation, can become
repulsive and support... | 0508207v1 |
2005-09-02 | Inhomogeneous soliton ratchets under two ac forces | We extend our previous work on soliton ratchet devices [L. Morales-Molina et
al., Eur. Phys. J. B 37, 79 (2004)] to consider the joint effect of two ac
forces including non-harmonic drivings, as proposed for particle ratchets by
Savele'v et al. [Europhys. Lett. 67}, 179 (2004); Phys. Rev. E {\bf 70} 066109
(2004)]. Cur... | 0509051v1 |
2005-10-26 | Multiple electron-hole scattering effect on quasiparticle properties in a homogeneous electron gas | We present a detailed study of a contribution of the T matrix accounting for
multiple scattering between an electron and a hole to the quasiparticle
self-energy. This contribution is considered as an additional term to the GW
self-energy. The study is based on a variational solution of the T-matrix
integral equation wi... | 0510684v2 |
2005-10-27 | Acoustic damping in Li$_2$O-2B$_2$O$_3$ glass observed by inelastic x-ray and optical Brillouin scattering | The dynamic structure factor of lithium-diborate glass has been measured at
several values of the momentum transfer $Q$ using high resolution inelastic
x-ray scattering. Much attention has been devoted to the low $Q$-range, below
the observed Ioffe-Regel crossover \qco{}$\simeq$ 2.1 nm$^{-1}$. We find that
below \qco{}... | 0510714v1 |
2005-12-07 | Acoustic attenuation probe for fermion superfluidity in ultracold atom gases | Dilute gas Bose-Einstein condensates (BEC's), currently used to cool
fermionic atoms in atom traps, can also probe the superfluidity of these
fermions. The damping rate of BEC-acoustic excitations (phonon modes), measured
in the middle of the trap as a function of the phonon momentum, yields an
unambiguous signature of... | 0512134v4 |
2006-01-11 | Apparent phonon side band modes in pi-conjugated systems: polymers, oligomers and crystals | The emission spectra of many pi-conjugated polymers and oligomers contain
side-band replicas with apparent frequencies that do not match the Raman active
mode frequencies. Using a time dependent model we show that in such many mode
systems, the increased damping of the time dependent transition dipole moment
correlatio... | 0601218v1 |
2006-03-01 | Renormalization of the electron-spin-fluctuation interaction in the t-t'-U Hubbard model | We study the renormalization of the electron-spin-fluctuation (el-sp) vertex
in a two-dimensional Hubbard model with nearest-neighbor (t) and
next-nearest-neighbor (t') hopping by a Quantum-Monte-Carlo calculation. Our
results show that for t'=0, the renormalized el-sp vertex decreases quite
generally with decreasing t... | 0603014v3 |
2006-07-18 | Equilibrium and non-equilibrium dynamics of the sub-ohmic spin-boson model | Employing the non-perturbative numerical renormalization group method, we
study the dynamics of the spin-boson model, which describes a two-level system
coupled to a bosonic bath with spectral density J(omega) propto omega^s. We
show that, in contrast to the case of ohmic damping, the delocalized phase of
the sub-ohmic... | 0607443v2 |
2006-09-29 | Quantum master equation for electron transport through quantum dots and single molecules | A quantum master equation (QME) is derived for the many-body density matrix
of an open current-carrying system weakly coupled to two metal leads. The
dynamics and the steady-state properties of the system for arbitrary bias are
studied using projection operator techniques, which keep track of number of
electrons in the... | 0610004v1 |
2006-10-25 | Pulse and hold strategy for switching current measurements | We investigate by theory and experiment, the Josephson junction switching
current detector in an environment with frequency dependent damping. Analysis
of the circuit's phase space show that a favorable topology for switching can
be obtained with overdamped dynamics at high frequencies. A pulse-and-hold
method is descr... | 0610704v2 |
2006-10-29 | Experimental Studies of Low-field Landau Quantization in Two-dimensional Electron Systems in GaAs/AlGaAs Heterostructures | By applying a magnetic field perpendicular to GaAs/AlGaAs two-dimensional
electron systems, we study the low-field Landau quantization when the thermal
damping is reduced with decreasing the temperature. Magneto-oscillations
following Shubnikov-de Haas (SdH) formula are observed even when their
amplitudes are so large ... | 0610805v1 |
2006-11-18 | Distributions of switching times of single-domain particles using a time quantified Monte Carlo method | Using a time quantified Monte Carlo scheme we performed simulations of the
switching time distribution of single mono-domain particles in the
Stoner-Wohlfarth approximation. We considered uniaxial anisotropy and different
conditions for the external applied field. The results obtained show the
switching time distributi... | 0611494v2 |
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