[Matts-arxiv] Matt's arXiv selection: week ending 6 August 2010

From: Matthew Davis <mdavis_at_physics.uq.edu.au>
Date: Mon, 18 Oct 2010 22:32:45 +1000

Dear subscribers,

This week's selection was compiled by Mike Garrett, and contains 34 new
abstracts and 18 replacements.

arXiv:0905.3263 (*cross-listing*)
Date: Wed, 20 May 2009 09:58:07 GMT (280kb,D)

Title: Energy cascades and spectra in turbulent Bose-Einstein condensates
Authors: Davide Proment, Sergey Nazarenko, Miguel Onorato
Categories: nlin.CD cond-mat.other physics.flu-dyn
Comments: 10 pages, 5 figures
DOI: 10.1103/PhysRevA.80.051603
   We present a numerical study of turbulence in Bose-Einstein condensates
within the 3D Gross-Pitaevskii equation. We concentrate on the direct energy
cascade in forced-dissipated systems. We show that behavior of the system is
very sensitive to the properties of the model at the scales greater than the
forcing scale, and we identify three different universal regimes: (1) a
non-stationary regime with condensation and transition from a four-wave to a
three-wave interaction process when the largest scales are not dissipated, (2)
a steady weak wave turbulence regime when largest scales are dissipated with a
friction-type dissipation, (3) a state with a scale-by-scale balance of the
linear and the nonlinear timescales when the large-scale dissipation is a
\\ ( http://arxiv.org/abs/0905.3263 , 280kb)
arXiv:1007.5331 (*cross-listing*)
Date: Thu, 29 Jul 2010 20:38:25 GMT (1502kb)

Title: Nonequilibrium dynamics of closed interacting quantum systems
Authors: Anatoli Polkovnikov, Krishnendu Sengupta, Alessandro Silva, Mukund
Categories: cond-mat.stat-mech cond-mat.quant-gas hep-th quant-ph
Comments: 22 pages, 2 Figures, Colloquium, submitted to RMP
   This colloquium gives an overview of recent theoretical and experimental
progress in the area of nonequilibrium dynamics of isolated quantum systems. We
particularly focus on quantum quenches: the temporal evolution following a
sudden or slow change of the coupling constants of the system Hamiltonian. We
discuss several aspects of the slow dynamics in driven systems and emphasize
the universality of such dynamics in gapless systems with specific focus on
dynamics near continuous quantum phase transitions. We also review recent
progress on understanding thermalization in closed systems through the
eigenstate thermalization hypothesis and discuss relaxation in integrable
systems. Finally we overview key experiments probing quantum dynamics in cold
atom systems and put them in the context of our current theoretical
\\ ( http://arxiv.org/abs/1007.5331 , 1502kb)
Date: Fri, 30 Jul 2010 06:50:20 GMT (752kb)

Title: Phase-space description of the magneto-optical trap
Authors: Rudy Romain (PhLAM), Daniel Hennequin (PhLAM), Philippe Verkerk
Categories: physics.atom-ph
   An exhaustive kinetic model for the atoms in a 1D Magneto-Optical Trap is
derived, without any approximations. It is shown that the atomic density is
described by a Vlasov-Fokker-Planck equation, coupled with two simple
differential equations describing the trap beam propagation. The analogy of
such a system with plasmas is discussed. This set of equations is then
simplified through some approximations, and it is shown that corrective terms
have to be added to the models usually used in this context.
\\ ( http://arxiv.org/abs/1007.5380 , 752kb)
Date: Fri, 30 Jul 2010 13:58:09 GMT (61kb)

Title: Energy relaxation in the Gross-Pitaevskii equation
Authors: Michiel Wouters and Vincenzo Savona
Categories: cond-mat.quant-gas
Comments: 4 pages, 3 figures
   We introduce a dissipation term in the Gross-Pitaevskii equation that
describes the stimulated relaxation of condensed bosons due to scattering with
a different type of particles. This situation applies to Bose-Einstein
condensates of quasi-particles in the solid state, such as magnons and
excitons. Our model is compatible with the phenomenology of superfluidity:
supercurrents are stable up to a critical speed and decay when they are faster.
\\ ( http://arxiv.org/abs/1007.5453 , 61kb)
Date: Fri, 30 Jul 2010 14:20:40 GMT (64kb)

Title: Canted Antiferromagnetic Order of Imbalanced Fermi-Fermi mixtures in
   Optical Lattices by Dynamical Mean-Field Theory
Authors: Michiel Snoek and Irakli Titvinidze and Walter Hofstetter
Categories: cond-mat.quant-gas
Comments: 6 pages, 5 figures
   We investigate antiferromagnetic order of repulsively interacting fermionic
atoms in an optical lattice by means of Dynamical Mean-Field Theory (DMFT).
Special attention is paid to the case of an imbalanced mixture, in which case
the antiferromagnetism is directed perpendicular to the ferromagnetic
polarization and canted. We take into account the presence of an underlying
harmonic trap, both in a local density approximation and by performing full
Real-Space DMFT calculations. For the moderately strong interactions considered
here, no Stoner instability towards a ferromagnetic phase is found. Phase
separation is only observed for strong imbalance and sufficiently large
\\ ( http://arxiv.org/abs/1007.5457 , 64kb)
Date: Fri, 30 Jul 2010 16:15:53 GMT (1058kb)

Title: Circular Dichroism of RbHe and RbN$_2$ Molecules
Authors: B. Lancor, E. Babcock, R. Wyllie, and T. G. Walker
Categories: physics.atom-ph
   We present measurements of the circular dichroism of optically pumped Rb
vapor near the D1 resonance line. Collisions with the buffer gases $^3$He and
N$_2$ reduce the transparency of the vapor, even when fully polarized. We use
two methods to measure this effect, show that the He results can be understood
from RbHe potential curves, and show how this effect conspires with the
spectral profile of the optical pumping light to increase the laser power
demands for optical pumping of very optically thick samples.
\\ ( http://arxiv.org/abs/1007.5486 , 1058kb)
arXiv:1008.0007 (*cross-listing*)
Date: Fri, 30 Jul 2010 20:13:54 GMT (65kb)

Title: Viscosity and scale invariance in the unitary Fermi gas
Authors: Tilman Enss, Rudolf Haussmann, Wilhelm Zwerger
Categories: cond-mat.quant-gas hep-th quant-ph
Comments: 19 pages, 9 figures
   We compute the shear viscosity of the unitary Fermi gas above the superfluid
transition temperature, using a diagrammatic technique that starts from the
exact Kubo formula. The formalism obeys a Ward identity associated with scale
invariance which guarantees that the bulk viscosity vanishes identically. For
the shear viscosity, vertex corrections and the associated Aslamazov-Larkin
contributions are shown to be crucial to reproduce the full Boltzmann equation
result in the high-temperature, low fugacity limit. The frequency dependent
shear viscosity $\eta(\omega)$ exhibits a Drude-like transport peak and a
power-law tail at large frequencies that is proportional to the Tan contact.
The weight in the transport peak is given by the equilibrium energy density,
consistent with a sum rule that has recently been derived by Taylor and
Randeria. Near the superfluid transition, the peak width is of the order $0.5\,
T_F$, thus invalidating a quasiparticle description. The ratio $\eta/s$ between
the static shear viscosity and the entropy density exhibits a minimum near the
superfluid transition temperature whose value is larger than the string theory
bound $\hbar/(4\pi k_B)$ by a factor of about seven.
\\ ( http://arxiv.org/abs/1008.0007 , 65kb)
Date: Sat, 31 Jul 2010 00:38:43 GMT (851kb)

Title: Superfluid state in the periodic Anderson model with attractive
Authors: Akihisa Koga and Philipp Werner
Categories: cond-mat.quant-gas
Comments: 16 pages, 8 figures
   We investigate the periodic Anderson model with attractive interactions by
means of dynamical mean-field theory (DMFT). Using a continuous-time quantum
Monte Carlo impurity solver, we study the competition between the superfluid
state and the paramagnetic Kondo insulating state, and determine the phase
diagram. At the chemical potential-induced phase transition from the Kondo
insulating state to the superfluid state, a low-energy peak characteristic of
the superfluid state appears inside the hybridization gap. We also address the
effect of the confining potential in optical lattice systems by means of
real-space DMFT calculations.
\\ ( http://arxiv.org/abs/1008.0036 , 851kb)
Date: Sat, 31 Jul 2010 07:15:36 GMT (186kb)

Title: Connection between rotation and miscibility in a two-component
   Bose-Einstein condensate
Authors: Takayuki Shimodaira, Tetsuo Kishimoto, Hiroki Saito
Categories: cond-mat.quant-gas
Comments: 6 pages, 7 figures
Journal-ref: Phys. Rev. A 82, 013647 (2010)
   A two-component Bose-Einstein condensate rotating in a toroidal trap is
investigated. The topological constraint depends on the density distribution of
each component along the circumference of the torus, and therefore the
quantization condition on the circulation can be controlled by changing the
miscibility using the Feshbach resonance. We find that the system exhibits a
variety of dynamics depending on the initial angular momentum when the
miscibility is changed.
\\ ( http://arxiv.org/abs/1008.0059 , 186kb)
Date: Sat, 31 Jul 2010 11:56:05 GMT (153kb)

Title: Correlation studies in a spin imbalanced fermionic superfluid in
   presence of a harmonic trap
Authors: Poulumi Dey, Saurabh Basu and Ram Kishore
Categories: cond-mat.supr-con cond-mat.other
Comments: 9 pages, 9 figures, 1 table
   We investigate different physical properties of a spin imbalanced fermionic
superfluid described by an attractive Hubbard model in presence of a harmonic
trap. To characterize the ground state of such a system, we compute various
correlation functions, such as pairing, density and current correlations To
underscore the effect of the trap, we compute these quantities as a function of
strength of the trapping potential. A distinguishing feature of a superfluid
state with population imbalance, is the appearance of a phase with spatially
modulating gap function, called the Fulde- Ferrell-Larkin-Ovchinnikov (FFLO)
phase which is present for both with and without trap. Trapping effects induce
lowering of particle density and yields an empty system in the limit of large
trapping depths.
\\ ( http://arxiv.org/abs/1008.0084 , 153kb)
arXiv:1008.0096 (*cross-listing*)
Date: Sat, 31 Jul 2010 14:39:39 GMT (3133kb,D)

Title: Sustained turbulence in the three-dimensional Gross-Pitaevskii model
Authors: Davide Proment, Sergey Nazarenko, Miguel Onorato
Categories: nlin.CD cond-mat.other
Comments: 37 pages, 22 figures
   We study the 3D forced-dissipated Gross-Pitaevskii equation. We force at
relatively low wave numbers, expecting to observe a direct energy cascade and a
consequent power-law spectrum of the form $k^{-\alpha}$. Our numerical results
show that the exponent $\alpha$ strongly depends on how the inverse particle
cascade is attenuated at $k$'s lower than the forcing wave number. If the
inverse cascade is arrested by a friction at low $k$'s, we observe an exponent
which is in good agreement with the weak wave turbulence prediction $k^{-1}$.
For a hypo-viscosity, a $k^{-2}$ spectrum is observed which we explain using a
critical balance argument. In simulations without any low-$k$ dissipation, a
condensate at $k=0$ is growing and the system goes through a strongly-turbulent
transition from a four-wave to a three-wave weak turbulence acoustic regime
with $k^{-3/2}$ Zakharov-Sagdeev spectrum. In this regime, we also observe a
spectrum for the incompressible kinetic energy which formally resembles the
Kolmogorov $k^{-5/3}$, but whose correct explanation should be in terms of the
Kelvin wave turbulence. The probability density functions for the velocities
and the densities are also discussed.
\\ ( http://arxiv.org/abs/1008.0096 , 3133kb)
Date: Sun, 1 Aug 2010 23:06:11 GMT (181kb)

Title: Hall viscosity, orbital spin, and geometry: paired superfluids and
   quantum Hall systems
Authors: N. Read, E.H. Rezayi
Categories: cond-mat.mes-hall cond-mat.quant-gas cond-mat.supr-con
Comments: 26 pages, 10 figures
   The Hall viscosity, a non-dissipative transport coefficient analogous to Hall
conductivity, is considered for quantum fluids in gapped or topological phases.
The relation to mean orbital spin per particle discovered in previous work by
one of us (NR) is elucidated with the help of examples, using the geometry of
shear transformations and rotations. For non-interacting particles in a
magnetic field, there are several ways to derive the result (even at non-zero
temperature), including standard linear response theory. Arguments for the
quantization, and the robustness of Hall viscosity to small changes in the
Hamiltonian that preserve rotational invariance, are given. Numerical
calculations of adiabatic transport are performed to check the predictions for
quantum Hall systems, with excellent agreement for trial states. The
coefficient of k^4 in the static structure factor is also considered, and shown
to be exactly related to the orbital spin and robust to perturbations in
rotation invariant systems also.
\\ ( http://arxiv.org/abs/1008.0210 , 181kb)
Date: Mon, 2 Aug 2010 02:34:12 GMT (186kb)

Title: Computational Theory of a splitting BEC using a Generalized Wannier
   basis I: Theory and Statics
Authors: Douglas K. Faust and William P. Reinhardt
Categories: cond-mat.quant-gas
Comments: 25 pages, 7 figures
   We present a novel and tractable method using what may be considered to be a
generalized Wannier basis to describe the splitting of a large number of
indistinguishable bosons trapped in a single potential well which is then
deformed into two wells during a finite time. This method incorporates
successful features of previous theoretical and computational assays into the
splitting problem, including mean field effects, and with access to the trap
parameters and particle numbers relevant to recent experiments. At all times we
are able to discern between a two-mode state and a state which is described
sufficiently by mean field theory and, further give a criterion and technique
for matching the two-mode theory to the zero-barrier state. We compare the
basis used in this model to the de-localized basis functions underlying
different models used in recent work. We show that only the generalized Wannier
basis displays the level crossing and emergence of two complex order parameters
with overall $U(1) \oplus U(1)$ symmetry as expected from a large$-N$ analog of
the superfluid to Mott insulator transition. Finally, we identify a universal
structure, independent of $N$ in this phase transition and discuss its
consequences for realizing true two-mode physics with a BEC which trends
towards the thermodynamic limit.
\\ ( http://arxiv.org/abs/1008.0217 , 186kb)
Date: Mon, 2 Aug 2010 07:14:54 GMT (15kb)

Title: The p=0 condensate is a myth
Authors: Yatendra S. Jain
Categories: cond-mat.quant-gas
Comments: 9 pages including 1 figure
   Analyzing some of the basic aspects of the dynamics of two bosons
(interacting through a central force) and their importance in determining the
ground state of a system like liquid $^4He$, it is unequivocally concluded that
our conventional belief in the existence $p=0$ condensate in the superfluid
state of such systems [including the state of Bose Einstein condensate (BEC) of
trapped dilute gases] is a myth.
\\ ( http://arxiv.org/abs/1008.0240 , 15kb)
Date: Mon, 2 Aug 2010 14:37:40 GMT (218kb,D)

Title: Reproducible mesoscopic superpositions of Bose-Einstein condensates and
   mean-field chaos
Authors: Bettina Gertjerenken, Stephan Arlinghaus, Niklas Teichmann, Christoph
Categories: cond-mat.quant-gas
Comments: 7 pages, 7 png figures, accepted for publication in Phys. Rev. A
   In a parameter regime for which the mean-field (Gross-Pitaevskii) dynamics
becomes chaotic, mesoscopic quantum superpositions in phase space can occur in
a double-well potential which is shaken periodically. For experimentally
realistic initial states like the ground state of some 100 atoms, the emergence
of mesoscopic quantum superpositions in phase space is investigated
numerically. It is shown to be reproducible even if the initial conditions
slightly change. While the final state is not a perfect superposition of two
distinct phase-states, the superposition is reached an order of magnitude
faster than in the case of the collapse and revival phenomenon. Furthermore, a
generator of entanglement is identified.
\\ ( http://arxiv.org/abs/1008.0314 , 218kb)
arXiv:1008.0361 (*cross-listing*)
Date: Mon, 2 Aug 2010 17:58:36 GMT (7200kb,D)

Title: Localization in one dimensional lattices with non-nearest-neighbor
   hopping: Generalized Anderson and Aubry-Andr\'e models
Authors: J. Biddle, D. J. Priour, B. Wang, S. Das Sarma
Categories: cond-mat.dis-nn quant-ph
Comments: 18 pages, 24 figures
   We study the quantum localization phenomena of noninteracting particles in
one-dimensional lattices based on tight-binding models with various forms of
hopping terms beyond the nearest neighbor, which are generalizations of the
famous Aubry-Andr\'e and noninteracting Anderson model. For the case with
deterministic disordered potential induced by a secondary incommensurate
lattice (i.e. the Aubry-Andr\'e model), we identify a class of self dual
models, for which the boundary between localized and extended eigenstates are
determined analytically by employing a generalized Aubry-Andr\'e
transformation. We also numerically investigate the localization properties of
non-dual models with next-nearest-neighbor hopping, Gaussian, and power-law
decay hopping terms. We find that even for these non-dual models, the
numerically obtained mobility edges can be well approximated by the
analytically obtained condition for localization transition in the self dual
models, as long as the decay of the hopping rate with respect to distance is
sufficiently fast. For the disordered potential with genuinely random
character, we examine scenarios with next-nearest-neighbor hopping,
exponential, Gaussian, and power-law decay hopping terms numerically. We find
that the higher order hopping terms can remove the symmetry in the localization
length about the energy band center compared to the Anderson model.
Furthermore, our results demonstrate that for the power-law decay case, there
exists a critical exponent below which mobility edges can be found. Our
theoretical results could, in principle, be directly tested in shallow atomic
optical lattice systems enabling non-nearest-neighbor hopping.
\\ ( http://arxiv.org/abs/1008.0361 , 7200kb)
Date: Mon, 2 Aug 2010 23:17:49 GMT (30kb)

Title: Microscopic Approach to Viscosities in Superfluid Fermi Gases: From BCS
   to BEC
Authors: H. Guo, D. Wulin, C. C. Chien, K. Levin
Categories: cond-mat.quant-gas
Comments: 4 pages, 2 figures
Report-no: LA-UR 10-05100
   We compute the shear $\eta$ and bulk viscosity $\zeta_2$ in a BCS-BEC
crossover scheme which is demonstrably consistent, via sum rules, with
conservation laws. The onset of a normal state pairing gap and the contribution
from bosonic (non-condensed pair) degrees of freedom lead to a reduction in the
magnitude of these viscosities at general temperatures $T$. When quantitatively
compared with shear viscosity experiments (we independently infer an estimated
lifetime from radio frequency data) the agreement is reasonable, as is a
comparison of $\eta/s$, where $s$ is the trap entropy density.
\\ ( http://arxiv.org/abs/1008.0423 , 30kb)
Date: Tue, 3 Aug 2010 00:31:08 GMT (10kb)

Title: Tonks-Girardeau and Super Tonks-Girardeau States of a Trapped 1D Spinor
   Bose Gas
Authors: M.D. Girardeau
Categories: cond-mat.quant-gas
Comments: 4 pages, no figures, revtex4. Submittes to Phys. Rev. A
   A harmonically trapped ultracold 1D spin-1 Bose gas with strongly repulsive
or attractive 1D even-wave interactions induced by a 3D Feshbach resonance is
studied. The exact ground state, a hybrid of Tonks-Girardeau (TG) and ideal
Fermi gases, is constructed in the TG limit of infinite even-wave repulsion by
a spinor Fermi-Bose mapping to a spinless ideal Fermi gas. It is then shown
that in the limit of infinite even-wave attraction this same state remains an
exact many-body eigenstate, now highly excited relative to the collapsed
generalized McGuire cluster ground state, showing that the hybrid TG state is
completely stable against collapse to this cluster ground state under a sudden
switch from infinite repulsion to infinite attraction. It is shown to be the TG
limit of a hybrid super Tonks-Girardeau (STG) state which is metastable under a
sudden switch from finite but very strong repulsion to finite but very strong
attraction. It should be possible to create it experimentally by a sudden
switch from strongly repulsive to strongly attractive interaction, as in the
recent Innsbruck experiment on a spin-polarized bosonic STG gas. In the case of
strong attraction there should also exist another STG state of much lower
energy, consisting of strongly bound dimers, a bosonic analog of a recently
predicted STG gas which is an ultracold gas of strongly bound bosonic dimers of
fermionic atoms, but it is shown that this STG state cannot be created by such
a switch from strong repulsion to strong attraction.
\\ ( http://arxiv.org/abs/1008.0428 , 10kb)
Date: Tue, 3 Aug 2010 06:31:17 GMT (163kb)

Title: Equilibration rates and negative absolute temperatures for ultracold
   atoms in optical lattices
Authors: Akos Rapp, Stephan Mandt, and Achim Rosch
Categories: cond-mat.quant-gas
   As highly tunable interacting systems, cold atoms in optical lattices are
ideal to realize and observe negative absolute temperatures, T < 0. We show
theoretically that by reversing the confining potential, stable superfluid
condensates at finite momentum and T < 0 can be created with low entropy
production for attractive bosons. They may serve as `smoking gun' signatures of
equilibrated T < 0. For fermions, we analyze the time scales needed to
equilibrate to T < 0. For moderate interactions, the equilibration time is
proportional to the square of the radius of the cloud and grows with increasing
interaction strengths as atoms and energy are transported by diffusive
\\ ( http://arxiv.org/abs/1008.0468 , 163kb)
Date: Tue, 3 Aug 2010 08:58:41 GMT (2074kb)

Title: Dynamical Behaviours of the Nonlinear Atom-Field Interaction in the
   Presence of Classical Gravity: f-Deformation Approach
Authors: Sh. Barzanjeh1, M. H. Naderi, and M. Soltanolkotabi
Categories: quant-ph
   In this paper, we investigate the effects of a classical gravitational field
on the dynamical behaviour of nonlinear atom-field interaction within the
framework of the f-deformed Jaynes-Cummings model. For this purpose, we first
introduce a set of new atomic operators obeying an f-deformed su(2) algebraic
structure to derive an effective Hamiltonian for the system under
consideration. Then by solving the Schrodinger equation in the interaction
picture and considering certain initial quantum states for the atomic and
radiation subsystems, we analyze the influence of gravity on the temporal
evolution of the atomic population inversion, atomic dipole squeezing, atomic
momentum diffusion, photon counting statistics, and deformed quadrature
squeezing of the radiation field.
\\ ( http://arxiv.org/abs/1008.0489 , 2074kb)
Date: Tue, 3 Aug 2010 12:10:47 GMT (46kb)

Title: Paired phases and Bose-Einstein condensation of spin-one bosons with
   attractive interaction
Authors: G. Pelka, K. Byczuk, J. Tworzydlo
Categories: cond-mat.quant-gas
Comments: 9 pages, 4 figures
   We analyze paired phases of cold bosonic atoms with the hyper spin S=1 and
with an attractive interaction. We derive mean-field self-consistent equations
for the matrix order parameter describing such paired bosons on an optical
lattice. The possible solutions are classified according to their symmetries.
In particular, we find that the self-consistent equations for the SO(3)
symmetric phase are of the same form as those for the scalar bosons with the
attractive interaction. This singlet phase may exhibit either the BCS type
pairing instability (BCS phase) or the BEC quasiparticle condensation together
with the BCS type pairing (BEC phase) for an arbitrary attraction U_0 in the
singlet channel of the two body interaction. We show that both condensate
phases become stable if a repulsion U_2 in the quintet channel is above a
critical value, which depends on U_0 and other thermodynamic parameters.
\\ ( http://arxiv.org/abs/1008.0529 , 46kb)
Date: Tue, 3 Aug 2010 14:01:26 GMT (453kb)

Title: Universal few-body physics in a harmonic trap
Authors: S. T\"olle, H.-W. Hammer, B.C. Metsch (Bonn Univ.)
Categories: cond-mat.quant-gas nucl-th
Comments: 19 pages, 10 figures
Report-no: HISKP-TH-10-20, INT-PUB-10-036
   Few-body systems with resonant short-range interactions display universal
properties that do not depend on the details of their structure or their
interactions at short distances. In the three-body system, these properties
include the existence of a geometric spectrum of three-body Efimov states and a
discrete scaling symmetry. Similar universal properties appear in 4-body and
possibly higher-body systems as well. We set up an effective theory for
few-body systems in a harmonic trap and study the modification of universal
physics for 3- and 4-particle systems in external confinement. In particular,
we focus on systems where the Efimov effect can occur and investigate the
dependence of the 4-body spectrum on the experimental tuning parameters.
\\ ( http://arxiv.org/abs/1008.0551 , 453kb)
arXiv:1008.0589 (*cross-listing*)
Date: Tue, 3 Aug 2010 16:36:37 GMT (410kb)

Title: Density of states in an optical speckle potential
Authors: G.M. Falco, Andrei A. Fedorenko, Jacopo Giacomelli, Michele Modugno
Categories: cond-mat.dis-nn cond-mat.quant-gas physics.optics
Comments: 11 pages, 11 figures, revtex4
   We study the single particle density of states of a one-dimensional speckle
potential, which is correlated and non-Gaussian. We consider both the repulsive
and attractive cases. The system is controlled by a single dimensionless
parameter determined by the mass of the particle, the correlation length and
the average intensity of the field. Depending on the value of this parameter,
the system exhibits different regimes, characterized by the localization
properties of the eigenfunctions. We calculate the corresponding density of
states using the statistical properties of the speckle potential. We find good
agreement with the results of numerical simulations.
\\ ( http://arxiv.org/abs/1008.0589 , 410kb)
Date: Tue, 3 Aug 2010 17:26:49 GMT (47kb)

Title: Magnetic phases of spin-3/2 fermions on a spatially anisotropic square
Authors: A. K. Kolezhuk and T. Vekua
Categories: cond-mat.quant-gas
Comments: 10 Revtex pages, 5 figures
   We study the magnetic phase diagram of spin-3/2 fermions in a spatially
anisotropic square optical lattice at quarter filling (corresponding to one
particle per lattice site). In the limit of the large on-site repulsion the
system can be mapped to the so-called Sp(N) Heisenberg spin model with N=4. We
analyze the Sp(N) spin model with the help of the large-N field-theoretical
approach and show that the effective theory corresponds to the Sp(N) extension
of the CP^{N-1} model, with the Lorentz invariance generically broken. We
obtain the renormalization flow of the model couplings and show that although
the Sp(N) terms are seemingly irrelevant, their presence leads to a
renormalization of the CP^{N-1} part of the action, driving a phase transition.
We further consider the influence of the external magnetic field (the quadratic
Zeeman effect), and present the qualitative analysis of the ground state phase
\\ ( http://arxiv.org/abs/1008.0598 , 47kb)
Date: Tue, 3 Aug 2010 18:07:26 GMT (372kb)

Title: Pulse pair generation from coherently prepared atomic ensembles
Authors: D. Moretti, D. Felinto, and J. W. R. Tabosa
Categories: quant-ph physics.atom-ph physics.optics
Comments: 9 pages, 6 figures
Journal-ref: Published online on European Physical Journal D (2010)
DOI: 10.1140/epjd/e2010-00200-y
   We report a detailed investigation on the generation of pulse pairs during
the readout of a coherence grating stored in a cold atomic ensemble. The pulse
shapes and the split of the retrieved energy between the two pulses are studied
as a function of the relative intensities of the two reading fields, and a
minimum is observed for the total retrieved energy. We introduce a simplified
analytical theory for the process, considering a three-level atomic system,
which explains all the most striking experimental features.
\\ ( http://arxiv.org/abs/1008.0610 , 372kb)
Date: Wed, 4 Aug 2010 00:21:10 GMT (765kb)

Title: Resonant atom-field interaction in large-size coupled-cavity arrays
Authors: Francesco Ciccarello
Categories: quant-ph
Comments: 8 pages, 4 figures
   We consider an array of coupled cavities with staggered inter-cavity
couplings, where each cavity mode interacts with an atom. In contrast to
large-size arrays with uniform-hopping rates where the atomic dynamics is known
to be frozen in the strong-hopping regime, we show that resonant atom-field
dynamics with significant energy exchange can occur in the case of staggered
hopping rates even in the thermodynamic limit. This effect arises from the
joint emergence of an energy gap in the free photonic dispersion relation and a
discrete frequency at the gap's center. The latter corresponds to a bound
normal mode stemming solely from the finiteness of the array length. Depending
on which cavity is excited, either the atomic dynamics is frozen or a
Jaynes-Cummings-like energy exchange is triggered between the bound photonic
mode and its atomic analogue. As these phenomena are effective with any number
of cavities, they are prone to be experimentally observed even in small-size
\\ ( http://arxiv.org/abs/1008.0677 , 765kb)
Date: Wed, 4 Aug 2010 07:02:23 GMT (1081kb)

Title: Expansion of matter waves in static and driven periodic potentials
Authors: C.E. Creffield, F. Sols, D. Ciampini, O. Morsch, and E. Arimondo
Categories: cond-mat.quant-gas
Comments: 4 pages, 3 eps figures
   We study the non-equilibrium dynamics of cold atoms held in an optical
lattice potential. The expansion of an initially confined atom cloud occurs in
two phases: an initial quadratic expansion followed by a ballistic behaviour at
long times. Accounting for this gives a good description of recent experimental
results, and provides a robust method to extract the effective intersite
tunneling from time-of-flight measurements.
\\ ( http://arxiv.org/abs/1008.0708 , 1081kb)
Date: Wed, 4 Aug 2010 08:38:44 GMT (235kb)

Title: Analytical approach to relaxation dynamics of condensed Bose gases
Authors: Miguel Escobedo, Federica Pezzotti, and Manuel Valle
Categories: cond-mat.quant-gas math-ph math.MP
Comments: 25 pages, 3 figures
   The temporal evolution of a perturbation of the equilibrium distribution of a
condensed Bose gas is investigated using the kinetic equation which describes
collision between condensate and noncondensate atoms. The dynamics is studied
in the low momentum limit where an analytical treatment is feasible. Explicit
results are given for the behavior at large times in different temperature
\\ ( http://arxiv.org/abs/1008.0714 , 235kb)
arXiv:1008.0788 (*cross-listing*)
Date: Wed, 4 Aug 2010 14:27:31 GMT (241kb)

Title: Number-conserving master equation theory for a dilute Bose-Einstein
Authors: Alexej Schelle, Thomas Wellens, Dominique Delande, and Andreas
Categories: quant-ph cond-mat.quant-gas physics.atom-ph
   We describe the transition of $N$ weakly interacting atoms into a
Bose-Einstein condensate within a number-conserving quantum master equation
theory. Based on the separation of time scales for condensate formation and
non-condensate thermalization, we derive a master equation for the condensate
subsystem in the presence of the non-condensate environment under the inclusion
of all two body interaction processes. We numerically monitor the condensate
particle number distribution during condensate formation, and derive a
condition under which the unique equilibrium steady state of a dilute, weakly
interacting Bose-Einstein condensate is given by a Gibbs-Boltzmann thermal
state of $N$ non-interacting atoms.
\\ ( http://arxiv.org/abs/1008.0788 , 241kb)
arXiv:1008.0847 (*cross-listing*)
Date: Wed, 4 Aug 2010 19:08:38 GMT (394kb)

Title: Atomic Dipole Traps with Amplified Spontaneous Emission: A Proposal
Authors: Jean-Fran\c{c}ois Cl\'ement, V\'eronique Zehnl\'e, Jean Claude
   Garreau, Pascal Szriftgiser
Categories: quant-ph physics.atom-ph
   We propose what we believe to be a novel type of optical source for
ultra-cold atomic Far Off-Resonance optical-dipole Traps (FORTs). The source is
based on an Erbium Amplified Spontaneous Emission (ASE) source that seeds a
high power Erbium Doped Fiber Amplifier (EDFA). The main interest of this
source is its very low coherence length, thus allowing an incoherent
superposition of several trapping beams without any optical interference. The
behavior of the superimposed beams is then a scalar sum greatly simplifying
complex configurations. As an illustration, we report an estimation of the
intensity noise of this source and an estimation of the atomic excess heating
rate for an evaporative cooling experiment application. They are both found to
be suitable for cold atoms experiments.
\\ ( http://arxiv.org/abs/1008.0847 , 394kb)
Date: Thu, 5 Aug 2010 00:18:13 GMT (109kb)

Title: Phase Diagram for a 2-D Two-Temperature Diffusive XY Model
Authors: Matthew D. Reichl, Charo I. Del Genio, and Kevin E. Bassler
Categories: cond-mat.stat-mech
Comments: 5 pages, 4 figures
   Using Monte Carlo simulations, we determine the phase diagram of a diffusive
two-temperature XY model. When the two temperatures are equal the system
becomes the equilibrium XY model with the continuous Kosterlitz-Thouless (KT)
vortex-antivortex unbinding phase transition. When the two temperatures are
unequal the system is driven by an energy flow through the system from the
higher temperature heat-bath to the lower temperature one and reaches a
far-from-equilibrium steady state. We show that the nonequilibrium phase
diagram contains three phases: A homogenous disordered phase and two phases
with long range, spin-wave order. Two critical lines, representing continuous
phase transitions from a homogenous disordered phase to two phases of long
range order, meet at the equilibrium the KT point. The shape of the
nonequilibrium critical lines as they approach the KT point is described by a
crossover exponent of phi = 2.52 \pm 0.05. Finally, we suggest that the
transition between the two phases with long-range order is first-order, making
the KT-point where all three phases meet a bicritical point.
\\ ( http://arxiv.org/abs/1008.0894 , 109kb)
Date: Thu, 5 Aug 2010 12:28:00 GMT (1732kb,D)

Title: Non-locality of Two Ultracold Trapped Atoms
Authors: Thom\'as Fogarty, John Goold, Mauro Paternostro and Thomas Busch
Categories: quant-ph
Comments: 14 pages, 7 figures
   We undertake a detailed analysis of the non-locality properties of the
fundamental problem of two trapped, distinguishable neutral atoms undergoing
s-wave scattering. We show that this interaction generates continuous variable
(CV) entanglement between the external degrees of freedom of the atoms and
consider its behaviour as a function of both, the distance between the
particles and the strength of the inter-particle scattering length. We first
quantify the entanglement in the ground state of the system at zero temperature
and then, adopting a phase-space approach, test the violation of the
Clauser-Horn-Shimony-Holt inequality at both zero and non-zero temperature and
under the effects of general dissipative local environments.
\\ ( http://arxiv.org/abs/1008.0962 , 1732kb)
Date: Thu, 5 Aug 2010 13:37:10 GMT (100kb)

Title: Stochastic simulations of fermionic dynamics with phase-space
Authors: M. Ogren, K. V. Kheruntsyan, J. F. Corney
Categories: physics.comp-ph cond-mat.quant-gas
   A Gaussian operator basis provides a means to formulate phase-space
simulations of the real- and imaginary-time evolution of quantum systems. Such
simulations are guaranteed to be exact while the underlying distribution
remains well-bounded, which defines a useful simulation time. We analyse the
application of the Gaussian phase-space representation to the dynamics of the
dissociation of an ultra-cold molecular gas. We show how the choice of mapping
to stochastic differential equations can be used to tailor the stochastic
behaviour, and thus the useful simulation time. In the phase-space approach, it
is only averages of stochastic trajectories that have a direct physical
meaning. Whether particular constants of the motion are satisfied by individual
trajectories depends on the choice of mapping, as we show in examples.
\\ ( http://arxiv.org/abs/1008.0970 , 100kb)
Date: Thu, 5 Aug 2010 14:46:00 GMT (331kb)

Title: Spatial Light Modulators for the Manipulation of Individual Atoms
Authors: Lukas Brandt, Cecilia Muldoon, Tobias Thiele, Jian Dong, Edouard
   Brainis and Axel Kuhn
Categories: physics.atom-ph physics.optics quant-ph
Comments: 9 pages, 5 figures
   We propose a novel dipole trapping scheme using spatial light modulators
(SLM) for the manipulation of individual atoms. The scheme uses a high
numerical aperture microscope to map the intensity distribution of a SLM onto a
cloud of cold atoms. The regions of high intensity act as optical dipole force
traps. With a SLM fast enough to modify the trapping potential in real time,
this technique is well suited for the controlled addressing and manipulation of
arbitrarily selected atoms.
\\ ( http://arxiv.org/abs/1008.0987 , 331kb)

The replacements:

arXiv:1006.2646 (*cross-listing*)
replaced with revised version Fri, 30 Jul 2010 06:45:09 GMT (197kb)

Title: Crossover in the Efimov spectrum
Authors: Ludovic Pricoupenko (LPTMC)
Categories: cond-mat.quant-gas quant-ph
\\ ( http://arxiv.org/abs/1006.2646 , 197kb)
replaced with revised version Fri, 30 Jul 2010 12:21:50 GMT (1650kb)

Title: Enhanced frequency up-conversion in Rb vapor
Authors: A. Vernier, S. Franke-Arnold, E. Riis and A. S. Arnold
Categories: physics.atom-ph
Comments: 6 pages, 4 figures. Modified to include referees' improvements
Journal-ref: Opt. Express 18, 17020 (2010)
DOI: 10.1364/OE.18.017020
\\ ( http://arxiv.org/abs/0911.0812 , 1650kb)
replaced with revised version Fri, 30 Jul 2010 15:35:39 GMT (211kb)

Title: Universal 1+2-body bound states in planar atomic wave guides
Authors: Ludovic Pricoupenko (LPTMC), Paolo Pedri (LPTMC, LPL)
Categories: cond-mat.other
\\ ( http://arxiv.org/abs/0812.3718 , 211kb)
replaced with revised version Fri, 30 Jul 2010 18:02:31 GMT (588kb)

Title: Spin transport in coupled spinor Bose gases
Authors: J.M. McGuirk
Categories: physics.atom-ph cond-mat.quant-gas
\\ ( http://arxiv.org/abs/1005.5174 , 588kb)
replaced with revised version Fri, 30 Jul 2010 22:32:02 GMT (211kb)

Title: Superfluidity and dimerization in a multilayered system of fermionic
   polar molecules
Authors: Andrew C. Potter, Erez Berg, Daw-Wei Wang, Bertrand I. Halperin,
   Eugene Demler
Categories: cond-mat.quant-gas
Comments: 4+epsilon pages
\\ ( http://arxiv.org/abs/1007.5061 , 211kb)
arXiv:0905.0343 (*cross-listing*)
replaced with revised version Sat, 31 Jul 2010 03:47:17 GMT (1665kb)

Title: Role of spatial inhomogeneity in dissociation of trapped molecular
Authors: Magnus Ogren and K. V. Kheruntsyan
Categories: cond-mat.quant-gas cond-mat.other quant-ph
Comments: Final published version; 23 pages, 13 figures
Journal-ref: Phys. Rev. A 82, 013641 (2010)
DOI: 10.1103/PhysRevA.82.013641
\\ ( http://arxiv.org/abs/0905.0343 , 1665kb)
replaced with revised version Mon, 2 Aug 2010 07:03:32 GMT (201kb)

Title: Critical Exponents and Universality in Bose-Einstein Condensation
Authors: Sanchari Goswami, Tapan Kumar Das and Anindya Biswas
Categories: cond-mat.quant-gas
Comments: reference added in version 2
\\ ( http://arxiv.org/abs/1007.4926 , 201kb)
replaced with revised version Mon, 2 Aug 2010 07:24:00 GMT (101kb)

Title: Not all pure entangled states are useful for sub shot-noise
Authors: Philipp Hyllus, Otfried G\"uhne, and Augusto Smerzi
Categories: quant-ph cond-mat.quant-gas
Comments: Published version, significantly revised according to the referee's
   comments. Results unchanged
Journal-ref: Phys. Rev. A 82, 012337 (2010)
\\ ( http://arxiv.org/abs/0912.4349 , 101kb)
replaced with revised version Mon, 2 Aug 2010 14:26:31 GMT (46kb)

Title: Spin-1/2 fermions with attractive interaction in an optical lattice
Authors: O. Fialko, A. Gammal, K. Ziegler
Categories: cond-mat.quant-gas
Comments: 10 pages, 7 figures; revised
Journal-ref: Phys. Lett. A, 2010
DOI: 10.1016/j.physleta.2010.07.038
\\ ( http://arxiv.org/abs/0904.4334 , 46kb)
replaced with revised version Mon, 2 Aug 2010 15:49:42 GMT (500kb,D)

Title: Bose-Einstein condensation at finite momentum and magnon condensation in
   thin film ferromagnets
Authors: Johannes Hick, Francesca Sauli, Andreas Kreisel, Peter Kopietz
Categories: cond-mat.quant-gas cond-mat.str-el
Comments: 9 pages, 4 figures, some typos corrected
\\ ( http://arxiv.org/abs/1007.3200 , 500kb)
replaced with revised version Mon, 2 Aug 2010 19:40:12 GMT (94kb)

Title: Role of interactions in time-of-flight expansion of atomic clouds from
   optical lattices
Authors: Joern N. Kupferschmidt (Cornell, Berlin), Erich J. Mueller (Cornell)
Categories: cond-mat.quant-gas
Comments: 6 pages, 3 figures
\\ ( http://arxiv.org/abs/1006.2042 , 94kb)
replaced with revised version Tue, 3 Aug 2010 08:20:09 GMT (2636kb,D)

Title: Atom chips with two-dimensional electron gases: near surface trapping
   and ultracold-atom microscopy of quantum electronic systems
Authors: G. Sinuco-Le\'on and B. Kaczmarek and P. Kr\"uger and T.M. Fromhold
Categories: cond-mat.quant-gas
Comments: 5 pages, 4 figures
\\ ( http://arxiv.org/abs/1007.5339 , 2636kb)
replaced with revised version Wed, 4 Aug 2010 02:52:52 GMT (73kb)

Title: Anisotropic Superfluidity in the Two-Species Polar Fermi Gas
Authors: Renyuan Liao and Joachim Brand
Categories: cond-mat.quant-gas cond-mat.supr-con
Comments: 4 pages, 5 figures
\\ ( http://arxiv.org/abs/1008.0514 , 73kb)
replaced with revised version Wed, 4 Aug 2010 11:28:28 GMT (12kb)

Title: Does one need to consider superconductivity as Bose-Einstein
Authors: B.V.Vasiliev
Categories: cond-mat.supr-con
\\ ( http://arxiv.org/abs/1006.4817 , 12kb)
replaced with revised version Wed, 4 Aug 2010 19:01:22 GMT (343kb)

Title: Intercepts of the momentum correlation functions in \mu-Bose gas model
   and their asymptotics
Authors: A.M. Gavrilik, A.P. Rebesh
Categories: quant-ph cond-mat.stat-mech hep-ph nucl-th
Comments: 11 pages (two column), 3 figures; v.2: small changes (in Abstract,
   Introduction, Conclusions), ref. added
\\ ( http://arxiv.org/abs/1007.5187 , 343kb)
replaced with revised version Thu, 5 Aug 2010 05:48:16 GMT (129kb)

Title: Critical velocity of flowing supersolids of dipolar Bose gases in
   optical lattices
Authors: Ippei Danshita, Daisuke Yamamoto
Categories: cond-mat.quant-gas cond-mat.other
Comments: 7 pages, 4 figures, published version
Journal-ref: Phys. Rev. A 82, 013645 (2010)
\\ ( http://arxiv.org/abs/1002.3925 , 129kb)
replaced with revised version Thu, 5 Aug 2010 11:41:51 GMT (548kb)

Title: Relative number squeezing in four-wave mixing of matter waves
Authors: Jean-Christophe Jaskula, Marie Bonneau, Guthrie B. Partridge,
   Valentina Krachmalnicoff, Piotr Deuar, Karen V. Kheruntsyan, Alain Aspect,
   Denis Boiron, Christoph I. Westbrook
Categories: cond-mat.quant-gas
Comments: 4 pages, 3 figures
\\ ( http://arxiv.org/abs/1008.0845 , 548kb)
replaced with revised version Thu, 5 Aug 2010 17:27:26 GMT (133kb,D)

Title: Dynamical Phase Transitions and Instabilities in Open Atomic Many-Body
Authors: Sebastian Diehl, Andrea Tomadin, Andrea Micheli, Rosario Fazio, Peter
Categories: cond-mat.quant-gas
Comments: 4+ pages, 3 figures
Journal-ref: Phys. Rev. Lett. 105, 015702 (2010)
DOI: 10.1103/PhysRevLett.105.015702
\\ ( http://arxiv.org/abs/1003.2071 , 133kb)

Till next time,

Dr M. J. Davis,                      Associate Professor in Physics
School of Mathematics and Physics,   ph  : +61 7 334 69824
The University of Queensland,        fax : +61 7 336 51242
Brisbane, QLD 4072,                  mdavis_at_physics.uq.edu.au
Australia.                           www.physics.uq.edu.au/people/mdavis/
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