[Matts-arxiv] Matt's arXiv selection: week ending 8 October 2010

From: Matthew Davis <mdavis_at_physics.uq.edu.au>
Date: Mon, 8 Nov 2010 14:56:10 +1000

Dear subscribers,

This week's selection was compiled by Simon Haine, and contains 34 new
abstracts and 12 replacements.

arXiv:0902.3980 (*cross-listing*)
Date: Mon, 23 Feb 2009 19:58:19 GMT (42kb,D)
Date (revised v2): Wed, 6 Oct 2010 20:18:10 GMT (42kb,D)

Title: Causality in Condensates: Grey Solitons as Remnants of BEC Formation
Authors: Wojciech H. Zurek
Categories: cond-mat.stat-mech hep-ph quant-ph
Comments: Typos in Eq. (3), (13), and (25) fixed
Journal-ref: Phys. Rev. Lett. 102, 105702 (2009)
DOI: 10.1103/PhysRevLett.102.105702
   Symmetry breaking during phase transitions can lead to the formation of
topological defects (such as vortex lines in superfluids). However, the usually
studied BEC's have the shape of a cigar, a geometry that impedes vortex
formation, survival, and detection. I show that, in elongated traps, one can
expect the formation of "grey solitons" (long-lived, non-topological "phase
defects") as a result of the same mechanism. Their number will rise
approximately in proportion to the transition rate. This steep rise is due to
the increasing size of the region of the BEC cigar where the phase of the
condensate wavefunction is chosen locally (rather than passed on from the
already formed BEC).
\\ ( http://arxiv.org/abs/0902.3980 , 42kb)
arXiv:1007.4260 (*cross-listing*)
Date: Sat, 24 Jul 2010 09:31:59 GMT (66kb)
Date (revised v2): Mon, 4 Oct 2010 15:22:21 GMT (66kb)

Title: The itinerant ferromagnetic phase of the Hubbard model
Authors: Giuseppe Carleo, Saverio Moroni, Federico Becca and Stefano Baroni
Categories: cond-mat.str-el cond-mat.other physics.comp-ph
   Using a newly developed quantum Monte Carlo technique, we provide strong
evidence for the stability of a saturated ferromagnetic phase in the
high-density regime of the two-dimensional infinite-U Hubbard model. By
decreasing the electron density, a discontinuous transition to a paramagnetic
phase is observed, accompanied by a divergence of the susceptibility on the
paramagnetic side. This behavior, resulting from a high degeneracy among
different spin sectors, is consistent with an infinite-order phase transition.
The remarkable stability of itinerant ferromagnetism renews the hope to
describe this phenomenon within a purely kinetic mechanism and will facilitate
the validation of experimental quantum simulators with cold atoms loaded in
optical lattices.
\\ ( http://arxiv.org/abs/1007.4260 , 66kb)
Date: Thu, 30 Sep 2010 20:39:44 GMT (145kb)

Title: Nonlinear Landau-Zener tunneling in quantum phase space
Authors: F. Trimborn, D. Witthaut, V. Kegel, and H. J. Korsch
Categories: quant-ph cond-mat.quant-gas
Comments: 26 pages, 12 figures
Journal-ref: New J. Phys. 12, 053010 (2010)
DOI: 10.1088/1367-2630/12/5/053010
   We present a detailed analysis of the Landau-Zener problem for an interacting
Bose-Einstein condensate in a time-varying double-well trap, especially
focussing on the relation between the full many-particle problem and the
mean-field approximation. Due to the nonlinear self-interaction a dynamical
instability occurs, which leads to a breakdown of adiabaticity condition and
thus fundamentally alters the dynamics. It is shown that essentially all
features of the Landau-Zener problem including the depletion of the condensate
mode can be already understood within a semiclassical phase space picture. In
particular, this treatment resolves the formerly imputed incommutability of the
adiabatic and semiclassical limits. The possibility to exploit Landau-Zener
sweeps to generate squeezed states for spectroscopic tasks is analysed in
detail. Moreover, we study the influence of phase noise and propose a
Landau-Zener sweep as a sensitive, yet readily implementable probe for
decoherence, since this has a significant effect on the transition rate for
slow parameter variations.
\\ ( http://arxiv.org/abs/1010.0016 , 145kb)
Date: Thu, 30 Sep 2010 23:37:35 GMT (174kb)

Title: Photon-photon gates in Bose-Einstein condensates
Authors: Arnaud Rispe, Bing He, Christoph Simon
Categories: quant-ph
Comments: 4 pages, 3 figures
   It has recently been shown that light can be stored in Bose-Einstein
condensates for over a second. Here we propose a method for realizing a
controlled phase gate between two stored photons. The photons are both stored
in the ground state of the effective trapping potential inside the condensate.
The collision-induced interaction is enhanced by adiabatically increasing the
trapping frequency and by using a Feshbach resonance. A controlled phase shift
of $\pi$ can be achieved in one second.
\\ ( http://arxiv.org/abs/1010.0037 , 174kb)
Date: Fri, 1 Oct 2010 01:18:04 GMT (30kb)

Title: T-matrix approach for few-body problems in ultracold atomic gases
Authors: Xiaoling Cui
Categories: cond-mat.quant-gas
Comments: 4 pages, 1 figure
   We propose a systematic T-matrix approach to solve two-body and few-body
problems in a dilute cold atomic gas. In most general cases, the problem is
reduced to a matrix equation expanded by various orthogonal molecular states
describing external center-of-mass motions of a pair of interacting particles;
while each matrix element is guaranteed to be finite by properly renormalizing
the short-range contributions for internal relative motions. We apply this
method to study three two-species fermions with different mass ratios in a
(rotating) harmonic trap, where distinct scattering properties tuned by the
mass ratio are analyzed and the transitions between different total angular
momenta are identified, which can shed light on quantum Hall physics in this
\\ ( http://arxiv.org/abs/1010.0044 , 30kb)
Date: Fri, 1 Oct 2010 09:44:46 GMT (589kb,D)

Title: Efficient Guiding of Cold Atoms though a Photonic Band Gap Fiber
Authors: S. Vorrath, S. A. M\"oller, P. Windpassinger, K. Bongs and K.
Categories: quant-ph physics.atom-ph
Comments: 8 pages, 3 figures
   We demonstrate the first guiding of cold atoms through a 88 mm long piece of
photonic band gap fiber. The guiding potential is created by a far-off
resonance dipole trap propagating inside the fiber with a hollow core of 12 mu
m. We load the fiber from a dark spot 85-Rb magneto optical trap and observe a
peak flux of more than 10^5 atoms/s at a velocity of 1.5 m/s. With an
additional reservoir optical dipole trap, a constant atomic flux of 1.5 10^4
atoms/s is sustained for more than 150\,ms. These results open up interesting
possibilities to study nonlinear light-matter interaction in a nearly
one-dimensional geometry and pave the way for guided matter wave
\\ ( http://arxiv.org/abs/1010.0101 , 589kb)
Date: Fri, 1 Oct 2010 10:02:56 GMT (602kb)

Title: Spin Squeezing, Negative Correlations, and Concurrence in the Quantum
   Kicked Top Model
Authors: Xiaoqian Wang, Jian Ma, Lijun Song, Xihe Zhang, Xiaoguang Wang
Categories: quant-ph
Comments: 8 pages, 6 figures
   We study spin squeezing, negative correlations, and concurrence in the
quantum kicked top model. We prove that the spin squeezing and negative
correlations are equivalent for spin systems with only symmetric Dicke states
populated. We numerically analyze spin squeezing parameters and concurrence in
this model, and find that the maximal spin squeezing direction, which refers to
the minimal pairwise correlation direction, is strongly influenced by quantum
chaos. Entanglement (spin squeezing) sudden death and sudden birth occur
alternatively for the periodic and quasi-periodic cases, while only
entanglement (spin squeezing) sudden death is found for the chaotic case.
\\ ( http://arxiv.org/abs/1010.0109 , 602kb)
Date: Fri, 1 Oct 2010 10:13:59 GMT (273kb,D)

Title: Loss-induced phase separation and pairing for 3-species atomic lattice
Authors: A. Privitera, I. Titvinidze, S.-Y. Chang, S. Diehl, A. J. Daley and W.
Categories: cond-mat.quant-gas
Comments: 5 pages, 3 figures
   We study the physics of a three-component Fermi gas in an optical lattice, in
the presence of a strong three-body constraint arising due to three-body loss.
Using analytical and numerical techniques, we show that an atomic color
superfluid phase is formed in this system and undergoes phase separation
between unpaired fermions and superfluid pairs. This phase separation survives
well above the critical temperature, giving a clear experimental signature of
the three-body constraint.
\\ ( http://arxiv.org/abs/1010.0114 , 273kb)
Date: Fri, 1 Oct 2010 10:24:32 GMT (5048kb,D)

Title: Energy cascade with small-scales thermalization, counterflow
   metastability and anomalous velocity of vortex rings in Fourier-truncated
   Gross-Pitaevskii equation
Authors: Giorgio Krstulovic and Marc Brachet
Categories: cond-mat.stat-mech
   The statistical equilibria of the dynamics of the Gross-Pitaevskii Equation
(GPE) with a finite range of spatial Fourier modes are characterized using a
new algorithm, based on a stochastically forced Ginzburg-Landau equation
(SGLE), that directly generates grand canonical distributions.. The
SGLE-generated distributions are validated against finite-temperature
GPE-thermalized states and exact low-temperature results. A standard
second-order $\lambda$-transition is exhibited. A new mechanism of GPE
thermalization through a direct cascade of energy is found using initial
conditions with mass and energy distributed at large scales. A long transient
with partial thermalization at small-scales is observed. Vortices are shown to
disappear as a prelude to final thermalization and their annihilation is
related to the contraction of vortex rings due to mutual friction. Increasing
the amount of dispersion at truncation wavenumber is shown to slowdown
thermalization and vortex annihilation. A bottleneck that produces spontaneous
effective self truncation with partial thermalization is characterized in the
limit of large dispersive effects. Metastable counter-flow states are generated
using the SGLE algorithm. Spontaneous nucleation of vortex ring is observed and
the corresponding Arrhenius law is characterized. Dynamical counter-flow
effects on vortex evolution are investigated. Longitudinal effects are produced
and measured. A dilatation of vortex rings is obtained for larger counterflows.
The vortex ring longitudinal velocity has a strong dependence on temperature,
an effect that is related to the presence of finite-amplitude Kelvin waves.
This anomalous vortex ring velocity is quantitatively reproduced by assuming
equipartition of energy of the Kelvin waves. Orders of magnitude are given for
the predicted effects in weakly interacting Bose-Einstein condensates and
superfluid $^4{\rm He}$.
\\ ( http://arxiv.org/abs/1010.0116 , 5048kb)
Date: Fri, 1 Oct 2010 13:53:24 GMT (373kb)

Title: How to observe dipolar effects in spinor Bose-Einstein condensates
Authors: Krzysztof Gawryluk, Kai Bongs, and Miroslaw Brewczyk
Categories: cond-mat.quant-gas
Comments: 4 pages, 3 figures
   We study a spinor condensate of alkali atoms in F = 1 hyperfine state under
the presence of an oscillating magnetic field. We find resonances which, due to
the dipolar interactions, magnify the transfer of atoms from mF = 1 to mF = 0
Zeeman sublevel. These resonances occur at magnetic fields of the order of
milligaus and are broad enough to enable observation of the famous Einstein-de
Haas effect, which is solely a dipolar effect, in systems of cold alkali gases.
\\ ( http://arxiv.org/abs/1010.0165 , 373kb)
arXiv:1010.0198 (*cross-listing*)
Date: Fri, 1 Oct 2010 16:25:38 GMT (1888kb)

Title: Cooling in strongly correlated optical lattices: prospects and
Authors: D. McKay and B. DeMarco
Categories: cond-mat.quant-gas physics.atom-ph
Comments: in review with Reports on Progress in Physics
   Optical lattices have emerged as ideal simulators for Hubbard models of
strongly correlated materials, such as the high-temperature superconducting
cuprates. In optical lattice experiments, microscopic parameters such as the
interaction strength between particles are well known and easily tunable.
Unfortunately, this benefit of using optical lattices to study Hubbard models
come with one clear disadvantage: the energy scales in atomic systems are
typically nanoKelvin compared with Kelvin in solids, with a correspondingly
miniscule temperature scale required to observe exotic phases such as d-wave
superconductivity. The ultra-low temperatures necessary to reach the regime in
which optical lattice simulation can have an impact-the domain in which our
theoretical understanding fails-have been a barrier to progress in this field.
To move forward, a concerted effort to develop new techniques for cooling and,
by extension, techniques to measure even lower temperatures. This article will
be devoted to discussing the concepts of cooling and thermometry, fundamental
sources of heat in optical lattice experiments, and a review of proposed and
implemented thermometry and cooling techniques.
\\ ( http://arxiv.org/abs/1010.0198 , 1888kb)
arXiv:1010.0293 (*cross-listing*)
Date: Sat, 2 Oct 2010 06:06:03 GMT (79kb)

Title: The scattering amplitude of ultracold atoms near the p-wave magnetic
   Feshbach Resonance
Authors: Peng Zhang, Pascal Naidon and Masahito Ueda
Categories: physics.atom-ph cond-mat.quant-gas quant-ph
Comments: 13 pages, 3 figs
   Most of the current theories on the p-wave superfluid in cold atomic gases
are based on the effective-range theory for the two-body scattering, where the
low energy p-wave scattering amplitude $f_1(k)$ is given by $%
f_1(k)=-1/[ik+1/(\mathcal{V}k^2)+1/\mathcal{R}]$, where $k$ is the incident
momentum, and $\mathcal{V}$ and $\mathcal{R}$ are the $k$-independent
scattering volume and effective-range, respectively. However, due to the
long-range nature of the van der Waals interaction between two colliding
ultracold atoms, the p-wave scattering amplitude of the two atoms is not
described by the effective-range theory. In this paper we provide an explicit
calculation for the p-wave scattering of two ultracold atoms near the p-wave
magnetic Feshbach resonance (PMFR). We show that the low energy p-wave
scattering amplitude in the presence of PMFR takes the form
where $\mathcal{V}^{\mathrm{eff}},$ $% \mathcal{S}^{\mathrm{eff}}$ and
$\mathcal{R}^{\mathrm{eff}}$ are $k$% -dependent parameters. Based on this
result, we show sufficient conditions for the effective range theory to be a
good approximation of the exact scattering amplitude. Using these conditions we
show that the effective-range theory is a good approximation for the p-wave
scattering in the ultracold gases of $^{6}$Li and $^{40}$K when the scattering
volume is enhanced by the resonance.
\\ ( http://arxiv.org/abs/1010.0293 , 79kb)
arXiv:1010.0391 (*cross-listing*)
Date: Sun, 3 Oct 2010 10:41:32 GMT (152kb,D)

Title: Dynamics of ring dark solitons in Bose-Einstein condensates and
   nonlinear optics
Authors: A.M. Kamchatnov and S.V. Korneev
Categories: nlin.PS cond-mat.quant-gas
Comments: 10 pages, 4 figures
Journal-ref: Physics Letters A 374 (2010), pp. 4625-4628
DOI: 10.1016/j.physleta.2010.09.019
   Quasiparticle approach to dynamics of dark solitons is applied to the case of
ring solitons. It is shown that the energy conservation law provides the
effective equations of motion of ring dark solitons for general form of the
nonlinear term in the generalized nonlinear Schroedinger or Gross-Pitaevskii
equation. Analytical theory is illustrated by examples of dynamics of ring
solitons in light beams propagating through a photorefractive medium and in
non-uniform condensates confined in axially symmetric traps. Analytical results
agree very well with the results of our numerical simulations.
\\ ( http://arxiv.org/abs/1010.0391 , 152kb)
Date: Mon, 4 Oct 2010 03:01:58 GMT (67kb,D)

Title: p-Wave Optical Feshbach Resonances in Yb-171
Authors: Krittika Goyal, Iris Reichenbach and Ivan Deutsch
Categories: physics.atom-ph cond-mat.quant-gas
Comments: 8 pages, 4 figures
   We study the use of an optical Feshbach resonance to modify the p-wave
interaction between ultracold polarized Yb-171 spin-1/2 fermions. A laser
exciting two colliding atoms to the 1S_0 + 3P_1 channel can be detuned near a
purely-long-range excited molecular bound state. Such an exotic molecule has an
inner turning point far from the chemical binding region and thus
three-body-recombination in the Feshbach resonance will be highly suppressed in
contrast to that typically seen in a ground state p-wave magnetic Feshbach
resonance. We calculate the excited molecular bound-state spectrum using a
multichannel integration of the Schr\"{o}dinger equation, including an external
perturbation by a magnetic field. From the multichannel wave functions, we
calculate the Feshbach resonance properties, including the modification of the
elastic p-wave scattering volume and inelastic spontaneous scattering rate. The
use of magnetic fields and selection rules for polarized light yields a highly
controllable system. We apply this control to propose a toy model for
three-color superfluidity in an optical lattice for spin-polarized Yb-171,
where the three colors correspond to the three spatial orbitals of the first
excited p-band. We calculate the conditions under which tunneling and on-site
interactions are comparable, at which point quantum critical behavior is
\\ ( http://arxiv.org/abs/1010.0465 , 67kb)
Date: Mon, 4 Oct 2010 10:17:29 GMT (248kb)

Title: Inelastic scattering of atoms in a double well
Authors: E. S. Annibale, O. Fialko and K. Ziegler
Categories: cond-mat.quant-gas
Comments: 12 pages, 9 figures
   We study a mixture of two light spin-1/2 fermionic atoms and two heavy atoms
%in a Mott state in a double well potential. Inelastic scattering processes
between both atomic species excite the heavy atoms and renormalize the
tunneling rate and the interaction of the light atoms (polaron effect). The
effective interaction of the light atoms changes its sign and becomes
attractive for strong inelastic scattering. This is accompanied by a crossing
of the energy levels from singly occupied sites at weak inelastic scattering to
a doubly occupied and an empty site for stronger inelastic scattering. We are
able to identify the polaron effect and the level crossing in the quantum
\\ ( http://arxiv.org/abs/1010.0527 , 248kb)
Date: Mon, 4 Oct 2010 19:38:23 GMT (93kb)

Title: Dimensional reduction of a binary Bose-Einstein condensate in mixed
Authors: L. E. Young S., L. Salasnich, S. K. Adhikari
Categories: cond-mat.quant-gas
   We present effective reduced equations for the study of a binary
Bose-Einstein condensate (BEC), where the confining potentials of the two BEC
components have distinct asymmetry so that the components belong to different
space dimensions as in a recent experiment [G. Lamporesi et al., Phys. Rev.
Lett. 104, 153202 (2010)]. Starting from a binary three-dimensional (3D)
Gross-Pitaevskii equation (GPE) and using a Lagrangian variational approach we
derive a binary effective nonlinear Schroedinger equation with components in
different reduced dimensions, e. g., the first component in one dimension and
the second in two dimensions as appropriate to represent a cigar-shaped BEC
coupled to a disk-shaped BEC. We demonstrate that the effective reduced binary
equation, which depend on the geometry of the system, is quite reliable when
compared with the binary 3D GPE and can be efficiently used to perform
numerical simulation and analytical calculation for the investigation of static
and dynamic properties of a binary BEC in mixed dimensions.
\\ ( http://arxiv.org/abs/1010.0666 , 93kb)
arXiv:1010.0726 (*cross-listing*)
Date: Mon, 4 Oct 2010 23:01:05 GMT (1568kb,D)

Title: An effective theory of pulse propagation in a nonlinear and disordered
   medium in two dimensions
Authors: G. Schwiete and A. M. Finkelstein
Categories: cond-mat.mes-hall cond-mat.quant-gas physics.optics
Comments: 15 pages, 11 figures. Prepared for "Perspectives of Mesoscopic
   Physics - Dedicated to Prof Yoseph Imry's 70th Birthday". This article is
   based on arXiv:0905.4722 [PRL 104, 103904 (2010)] and contains additional
   information and illustrations
   We develop an effective theory of pulse propagation in a nonlinear {\it and}
disordered medium. The theory is formulated in terms of a nonlinear diffusion
equation. Despite its apparent simplicity this equation describes novel
phenomena which we refer to as "locked explosion" and "diffusive" collapse. The
equation can be applied to such distinct physical systems as laser beams
propagating in disordered photonic crystals or Bose-Einstein condensates
expanding in a disordered environment.
\\ ( http://arxiv.org/abs/1010.0726 , 1568kb)
Date: Tue, 5 Oct 2010 00:02:57 GMT (121kb)

Title: Photoionization Rates of Cs Rydberg Atoms in a 1064 nm Far Off-Resonance
Authors: J. Tallant and D. Booth and J. P. Shaffer
Categories: physics.atom-ph
Comments: 12 pages, 4 figures
   Experimental measurements of photoionization rates of $nD_{5/2}$ Rydberg
states of Cs ($50 \leq n \leq 75$) in a 1064 nm far off-resonance dipole trap
are presented. The photoionization rates are obtained by measuring the
lifetimes of Rydberg atoms produced inside of a 1064 nm far off-resonance trap
and comparing the lifetimes to corresponding control experiments in a
magneto-optical trap. Experimental results for the control experiments agree
with recent theoretical predictions for Rydberg state lifetimes and measured
photoionization rates are in agreement with transition rates calculated from a
model potential.
\\ ( http://arxiv.org/abs/1010.0734 , 121kb)
Date: Tue, 5 Oct 2010 09:11:14 GMT (673kb)

Title: Equilibrium and off-equilibrium trap-size scaling in 1D ultracold
   bosonic gases
Authors: Massimo Campostrini and Ettore Vicari
Categories: cond-mat.quant-gas cond-mat.stat-mech
Comments: 24 pages, 36 figs
   We study some aspects of equilibrium and off equilibrium quantum dynamics of
dilute bosonic gases in the presence of a trapping potential. We consider
systems with a fixed number of particles N and study their scaling behavior
with increasing the trap size. We focus on one-dimensional (1D) bosonic
systems, such as gases described by the Lieb-Liniger model and its
Tonks-Girardeau limit of impenetrable bosons, and gases constrained in optical
lattices as described by the Bose-Hubbard model. We study their quantum
(zero-temperature) behavior at equilibrium and off equilibrium during the
unitary time evolution arising from changes of the trapping potential, which
may be instantaneous or described by a power-law time dependence, starting from
the equilibrium ground state for a initial trap size. Renormalization-group
scaling arguments, analytical and numerical calculations show that the
trap-size dependence of the equilibrium and off-equilibrium dynamics can be
cast in the form of a trap-size scaling in the low-density regime,
characterized by universal power laws of the trap size, in dilute gases with
repulsive contact interactions and lattice systems described by the
Bose-Hubbard model. The scaling functions corresponding to several physically
interesting observables are computed. Our results are of experimental relevance
for systems of cold atomic gases trapped by tunable confining potentials.
\\ ( http://arxiv.org/abs/1010.0806 , 673kb)
Date: Tue, 5 Oct 2010 12:09:48 GMT (144kb)

Title: Correlation function of weakly interacting bosons in a disordered
Authors: B. Deissler, E. Lucioni, M. Modugno, G. Roati, L. Tanzi, M. Zaccanti,
   M. Inguscio, G. Modugno
Categories: cond-mat.quant-gas cond-mat.dis-nn
Comments: 16 pages, 8 figures
   One of the most important issues in disordered systems is the interplay of
the disorder and repulsive interactions. Several recent experimental advances
on this topic have been made with ultracold atoms, in particular the
observation of Anderson localization, and the realization of the disordered
Bose-Hubbard model. There are however still questions as to how to
differentiate the complex insulating phases resulting from this interplay, and
how to measure the size of the superfluid fragments that these phases entail.
It has been suggested that the correlation function of such a system can give
new insights, but so far little experimental investigation has been performed.
Here, we show the first experimental analysis of the correlation function for a
weakly interacting, bosonic system in a quasiperiodic lattice. We observe an
increase in the correlation length as well as a change in shape of the
correlation function in the delocalization crossover from Anderson glass to
coherent, extended state. In between, the experiment indicates the formation of
progressively larger coherent fragments, consistent with a fragmented BEC, or
Bose glass.
\\ ( http://arxiv.org/abs/1010.0853 , 144kb)
Date: Wed, 6 Oct 2010 07:13:22 GMT (2608kb)

Title: Ferromagnetic Resonance in Spinor Dipolar Bose--Einstein Condensates
Authors: Masashi Yasunaga and Makoto Tsubota
Categories: cond-mat.quant-gas
Comments: 8 pages, 10 figures
   We used the Gross--Pitaevskii equations to investigate ferromagnetic
resonance in spin-1 Bose--Einstein condensates with a magnetic dipole-dipole
interaction. By introducing the dipole interaction, we obtained equations
similar to the Kittel equations used to represent ferromagnetic resonance in
condensed matter physics. These equations indicated that the ferromagnetic
resonance originated from dipolar interaction, and that the resonance frequency
depended upon the shape of the condensate. Furthermore, spin currents driven by
spin diffusions are characteristic of this system.
\\ ( http://arxiv.org/abs/1010.1075 , 2608kb)
arXiv:1010.1122 (*cross-listing*)
Date: Wed, 6 Oct 2010 11:08:05 GMT (5212kb)

Title: Non-degenerate four-wave mixing in rubidium vapor: transient regime
Authors: F. E. Becerra, R. T. Willis, S. L. Rolston, H. J. Carmichael, and L.
   A. Orozco
Categories: physics.optics physics.atom-ph quant-ph
Comments: 11 pages, 11 figures, to be published in Physical Review A
   We investigate the transient response of the generated light from Four-Wave
Mixing (FWM) in the diamond configuration using a step-down field excitation.
The transients show fast decay times and oscillations that depend on the
detunings and intensities of the fields. A simplified model taking into account
the thermal motion of the atoms, propagation, absorption and dispersion effects
shows qualitative agreement with the experimental observations with the energy
levels in rubidium (5S1/2, 5P1/2, 5P3/2 and 6S1/2). The atomic polarization
comes from all the contributions of different velocity classes of atoms in the
ensemble modifying dramatically the total transient behavior of the light from
\\ ( http://arxiv.org/abs/1010.1122 , 5212kb)
arXiv:1010.1162 (*cross-listing*)
Date: Wed, 6 Oct 2010 14:16:57 GMT (2038kb,D)

Title: The Accelerating Universe
Authors: Dragan Huterer (University of Michigan)
Categories: astro-ph.CO physics.pop-ph
Comments: Invited review chapter for book aimed at general scientists (ed. D.
   Goodstein); 25 pages, 10 figures
   In this article we review the discovery of the accelerating universe using
type Ia supernovae. We then outline ways in which dark energy - component that
causes the acceleration - is phenomenologically described. We finally describe
principal cosmological techniques to measure large-scale properties of dark
energy. This chapter complements other articles in this book that describe
theoretical understanding (or lack thereof) of the cause for the accelerating
\\ ( http://arxiv.org/abs/1010.1162 , 2038kb)
Date: Wed, 6 Oct 2010 16:25:58 GMT (29kb)

Title: Bell's Theory with no Locality assumption
Authors: Charles Tresser
Categories: quant-ph
Report-no: 12 pages, 0 figures
Journal-ref: Eur. Phys. J. D 58, 385-396 (2010)
DOI: 10.1140/epjd/e2010-00122-8
   We prove versions of the Bell and the GHZ Theorems that do not assume
Locality but only the Effect After Cause Principle (EACP) according to which
for any Lorentz observer the value of an observable cannot change because of an
event that happens after the observable is measured. We show that the EACP is
strictly weaker than Locality. As a consequence of our results, Locality cannot
be considered as the common cause of the contradictions obtained in all
versions of Bell's Theory. All versions of Bell's Theorem assume Weak Realism
according to which the value of an observable is well defined whenever the
measurement could be made and some measurement is made. As a consequence of our
results, Weak Realism becomes the only hypothesis common to the contradictions
obtained in all versions of Bell's Theory. Usually, one avoids these
contradictions by assuming Non-Locality; this would not help in our case since
we do not assume Locality. This work indicates that it is Weak Realism, not
Locality, that needs to be negated to avoid contradictions in microscopic
physics, at least if one refuses as false the de Broglie-Bohm Hidden Variable
theory because of its essential violation of Lorentz invariance.
\\ ( http://arxiv.org/abs/1010.1190 , 29kb)
Date: Wed, 6 Oct 2010 16:38:05 GMT (26kb)

Title: Bell's Theory with no Locality assumption: putting Free Will at work
Authors: Charles Tresser
Categories: quant-ph
Comments: 13 pages, 0 figures: Conference in honor of Pierre Coullet's 60th
   Birthday; Vina del Mar, Chile, December 2009. This paper completes the
   original Bell Theorem part of Charles Tresser:"Bell's theory with no locality
   assumption", Eur.Phys.J. D 58, 385-396 (2010); (DOI: 10.1140/ep
   We prove a version of the Bell's Theorem that does not assume Locality but
only the Effect After Cause Principle (EACP) according to which for any Lorentz
observer the value of an observable cannot change because of an event that
happens after the observable is measured. Since the EACP is compatible both
with Locality and with Non-Locality, Locality cannot be considered as the
common cause of the contradictions obtained in all versions of Bell's Theory.
By definition, all versions of Bell's Theorem assume Weak Realism according to
which the value of an observable needed in the discussion of Bell's Theorem is
well defined whenever the measurement could be made and some measurement is
made. As a consequence of our results, Weak Realism becomes the only hypothesis
common to the contradictions obtained in all versions of Bell's Theory. This
work indicates that it is Weak Realism, not Locality, that needs to be negated
to avoid the contradictions in microscopic Physics associated to Bell's Theory,
at least if one refuses as false the de Broglie-Bohm Hidden Variable theory
because of its essential violation of Lorentz invariance. This paper completes
with much more details the genuine Bell Theorem part of a previous paper. That
paper also offered a treatment of the GHZ entanglement, a treatment which did
not suffer from the lack of clarity of the definition of the EACP.
\\ ( http://arxiv.org/abs/1010.1196 , 26kb)
Date: Wed, 6 Oct 2010 16:42:14 GMT (54kb)

Title: Bethe-Salpeter equations for the collective-mode spectrum of a
   superfluid Fermi gas in a moving optical lattice
Authors: Zlatko Koinov
Categories: cond-mat.str-el
   We derive the Bethe-Salpeter (BS) equations for the collective-mode spectrum
of superfluid Fermi gases of equal mixture of atomic Fermi gas of two hyperfine
states loaded into a moving optical lattice. In a moving lattice the superfluid
state is unstable due to spontaneous emission of the short-wavelength rotonlike
excitations which appear in the spectrum of the collective modes. It is shown
that the spectrum obtained by the BS equations is in an excellent agreement
with the collective-mode dispersion calculated by the perturbation approach,
while there are some differences between the results obtained by density
response function method and by the BS approach. The difference increases with
increasing the lattice velocity, which can be seen in the analytical
approximations for the dispersion relation in the long-wavelength limit in a
weak-coupling regime.
\\ ( http://arxiv.org/abs/1010.1200 , 54kb)
Date: Wed, 6 Oct 2010 17:19:50 GMT (236kb,D)

Title: Direct probing of non-classical single-photon wavepacket
Authors: Kaisa Laiho, Katiuscia N. Cassemiro, David Gross, and Christine
Categories: quant-ph
Comments: 4 pages, 4 figures
   We investigate quantum properties of pulsed light fields point-by-point in
phase space. We probe the negative region of the Wigner function of a single
photon state generated by means of waveguided parametric down-conversion. This
capability is achieved by employing loss-tolerant photon number resolving
detection, allowing to directly observe the oscillations of the photon number
statistics in dependence of applied displacements in phase space. Our scheme is
highly mode sensitive and can reveal the single-mode character of the signal
\\ ( http://arxiv.org/abs/1010.1208 , 236kb)
Date: Wed, 6 Oct 2010 18:49:22 GMT (256kb)

Title: Stimulated Raman adiabatic passage into continuum
Authors: A. A. Rangelov, N. V. Vitanov, and E. Arimondo
Categories: quant-ph
Journal-ref: Phys. Rev. A 76, 043414 (2007)
DOI: 10.1103/PhysRevA.76.043414
   We propose a technique which produces nearly complete ionization of the
population of a discrete state coupled to a continuum by a two-photon
transition via a lossy intermediate state whose lifetime is much shorter than
the interaction duration. We show that using counterintuitively ordered pulses,
as in stimulated Raman adiabatic passage (STIRAP), wherein the pulse coupling
the intermediate state to the continuum precedes and partly overlaps the pulse
coupling the initial and intermediate states, greatly increases the ionization
signal and strongly reduces the population loss due to spontaneous emission
through the lossy state. For strong spontaneous emission from that state,
however, the ionization is never complete because the dark state required for
STIRAP does not exist. We demonstrate that this drawback can be eliminated
almost completely by creating a laser-induced continuum structure (LICS) by
embedding a third discrete state into the continuum with a third control laser.
This LICS introduces some coherence into the continuum, which enables a
STIRAP-like population transfer into the continuum. A highly accurate analytic
description is developed and numerical results are presented for Gaussian pulse
\\ ( http://arxiv.org/abs/1010.1228 , 256kb)
Date: Wed, 6 Oct 2010 21:08:57 GMT (146kb)

Title: Counterintuitive transitions between crossing energy levels
Authors: A. A. Rangelov, J. Piilo, and N. V. Vitanov
Categories: quant-ph
Journal-ref: Phys. Rev. A 72, 053404 (2005)
DOI: 10.1103/PhysRevA.72.053404
   We calculate analytically the probabilities for intuitive and
counterintuitive transitions in a three-state system, in which two parallel
energies are crossed by a third, tilted energy. The state with the tilted
energy is coupled to the other two states in a chainwise linkage pattern with
constant couplings of finite duration. The probability for a counterintuitive
transition is found to increase with the square of the coupling and decrease
with the squares of the interaction duration, the energy splitting between the
parallel energies, and the tilt (chirp) rate. Physical examples of this model
can be found in coherent atomic excitation and optical shielding in cold atomic
\\ ( http://arxiv.org/abs/1010.1280 , 146kb)
Date: Wed, 6 Oct 2010 23:31:34 GMT (75kb)

Title: Quantum Criticality of 1D Attractive Fermi Gas
Authors: Xiwen Guan and Tin-Lun Ho
Categories: cond-mat.quant-gas
Comments: 4+2 pages, 5 eps figures, Fig. 5 was improved
   We obtain analytical equation of state for one-dimensional strongly
attractive Fermi gas for all parameter regime in current experiments. The
critical properties of the system are described by that of free fermions and
that mixtures of fermions with mass $m$ and $2m$. We also show how these
critical properties of bulk systems can be revealed from the density profile of
trapped Fermi gas and can be used to determine the T=0 phase boundary.
\\ ( http://arxiv.org/abs/1010.1301 , 75kb)
Date: Thu, 7 Oct 2010 10:02:57 GMT (237kb)

Title: The self-consistent microscopic model of an energy spectrum of a
   superfluity $^{4}$He with the Hermitian form of Bogoliubov-Zubarev
Authors: K.V. Grigorishin and B.I. Lev
Categories: cond-mat.other cond-mat.quant-gas
   Based on the collective variables representation with the Hermitian form of
Bogoliubov-Zubarev Hamiltonian the self-consistent oscillator model of a ground
state and excited states of Bose liquid has been proposed. The new method of
calculation of anharmonic terms in this Hamiltonian and its interpretation have
been presented. The dispersion equation for a collective excitation in a
superfluid $^{4}$He has been obtained in self-consistent way, where real and
virtual processes of decay of a collective excitation were considered. The end
point, determined by a threshold of collective excitation's decay on two
rotons, of the dispersion curve has been obtained and it was shown that the
dispersion curve strongly depends on property of its stability. An approach
with a structure factor has been realized without using of any adaption
parameters. Based on the oscillator model the new method of self-consistent
calculation of a ground state energy and density of Bose condensate has been
proposed. The model of suppression of Bose condensate has been presented.
\\ ( http://arxiv.org/abs/1010.1382 , 237kb)
arXiv:1010.1431 (*cross-listing*)
Date: Thu, 7 Oct 2010 13:39:47 GMT (17kb)

Title: Density and Temperature of Fermions from Quantum Fluctuations
Authors: Hua Zheng and Aldo Bonasera
Categories: nucl-th cond-mat.quant-gas nucl-ex
   A novel method to determine the density and temperature of a system is
proposed based on quantum fluctuations typical of Fermions in the limit where
the reached temperature T is small compared to the Fermi energy $\epsilon_f$ at
a given density $\rho$. Quadrupole and particle multiplicity fluctuations
relations are derived in terms of $\frac{T}{\epsilon_f}$. This method is valid
for infinite and finite fermionic systems, in particular we apply it to heavy
ion collisions using the Constrained Molecular Dynamics (CoMD) approach which
includes the Fermi statistics. A preliminary comparison to available
experimental data is discussed as well. We stress the differences with methods
based on classical approximations. The derived 'quantum' temperatures are
systematically lower than the corresponding 'classical' ones. With the proposed
method we may get important informations on the Equation of State (EOS) of
quantum Fermi systems to order O($\frac{T}{\epsilon_f})^3$, in particular near
the Liquid-Gas (LG) phase transition and at very low densities where quantum
effects are dominant.
\\ ( http://arxiv.org/abs/1010.1431 , 17kb)
Date: Thu, 7 Oct 2010 18:07:41 GMT (75kb)

Title: Coherent Radiation by a Spherical Medium of Resonant Atoms
Authors: Sudhakar Prasad and Roy J. Glauber
Categories: physics.optics
Report-no: PraGla05
   Radiation by the atoms of a resonant medium is a cooperative process in which
the medium participates as a whole. In two previous papers \cite{PG00,GP00}, we
treated this problem for the case of a medium having slab geometry, which,
under plane wave excitation, supports coherent waves that propagate in one
dimension. We extend the treatment here to the three-dimensional problem,
focusing principally on the case of spherical geometry. By regarding the
radiation field as a superposition of electric and magnetic multipole fields of
different orders, we express it in terms of suitably defined scalar fields. The
latter fields possess a sequence of exponentially decaying eigenmodes
corresponding to each multipole order. We consider several examples of
spherically symmetric initial excitations of a sphere. Small uniformly excited
spheres, we find, tend to radiate superradiantly, while the radiation from a
large sphere with an initially excited inner core exhibits temporal
oscillations that result from the participation of a large number of coherently
excited amplitudes in different modes. The frequency spectrum of the emitted
radiation possesses a rich structure, including a frequency gap for large
spheres and sharply defined and closely spaced peaks caused by the small
frequency shifts and even smaller decay rates characteristic of the majority of
\\ ( http://arxiv.org/abs/1010.1501 , 75kb)
Date: Thu, 7 Oct 2010 19:25:58 GMT (1077kb,D)

Title: Differential Light Shift Cancellation in a Magnetic-Field-Insensitive
   Transition of $^{87}$Rb
Authors: R. Chicireanu and K. D. Nelson and S. Olmschenk and N. Lundblad and A.
   Derevianko and J. V. Porto
Categories: quant-ph physics.atom-ph
Comments: 5 pages, 4 figures
   We demonstrate near-complete cancellation of the differential light shift of
a two-photon magnetic-field-insensitive microwave hyperfine (clock) transition
in $^{87}$Rb atoms trapped in an optical lattice. Up to $95(2)%$ of the
differential light shift is canceled while maintaining magnetic-field
insensitivity. This technique should have applications in quantum information
and frequency metrology.
\\ ( http://arxiv.org/abs/1010.1520 , 1077kb)

The replacements:

replaced with revised version Fri, 1 Oct 2010 02:05:01 GMT (328kb)

Title: Three-vortex configurations in trapped Bose-Einstein condensates
Authors: J. A. Seman, E. A. L. Henn, M. Haque, R. F. Shiozaki, E. R. F. Ramos,
   M. Caracanhas, C. Castelo Branco, P. E. S. Tavares, F. J. Poveda-Cuevas, G.
   Roati, K. M. F. Magalh\~aes and V. S. Bagnato
Categories: cond-mat.quant-gas
Comments: 4 pages, 4 figures
Journal-ref: Published in Physical Review A 82, 033616 (2010)
DOI: 10.1103/PhysRevA.82.033616
\\ ( http://arxiv.org/abs/0907.1584 , 328kb)
arXiv:1007.4441 (*cross-listing*)
replaced with revised version Fri, 1 Oct 2010 09:38:35 GMT (5072kb,D)

Title: Dispersive bottleneck delaying thermalization of turbulent Bose-Einstein
Authors: Giorgio Krstulovic and Marc Brachet
Categories: physics.flu-dyn cond-mat.quant-gas
\\ ( http://arxiv.org/abs/1007.4441 , 5072kb)
replaced with revised version Fri, 1 Oct 2010 16:24:21 GMT (520kb)

Title: $F$-wave pairing of cold atoms in optical lattices
Authors: Wei-Cheng Lee, Congjun Wu, S. Das Sarma
Categories: cond-mat.quant-gas cond-mat.supr-con
Comments: 9 pages, 5 figures
\\ ( http://arxiv.org/abs/0905.1146 , 520kb)
arXiv:1003.3096 (*cross-listing*)
replaced with revised version Fri, 1 Oct 2010 19:33:00 GMT (33kb)

Title: Fermi-Bose Mixtures Near Broad Interspecies Feshbach Resonances
Authors: Jun Liang Song, Mohammad S. Mashayekhi and Fei Zhou
Categories: cond-mat.quant-gas physics.atom-ph
Comments: 5 pages, 4 figures
\\ ( http://arxiv.org/abs/1003.3096 , 33kb)
replaced with revised version Sat, 2 Oct 2010 00:56:12 GMT (218kb)

Title: Dynamic Structure Factor of Normal Fermi Gas from Collisionless to
   Hydrodynamic Regime
Authors: Shohei Watabe, and Tetsuro Nikuni
Categories: cond-mat.quant-gas
Comments: 19 pages, 9 figures
Journal-ref: Phys. Rev. A 82, 033622 (2010)
DOI: 10.1103/PhysRevA.82.033622
\\ ( http://arxiv.org/abs/1006.5540 , 218kb)
replaced with revised version Sat, 2 Oct 2010 23:43:29 GMT (21kb)

Title: Stability of the superfluid state in a disordered 1D ultracold fermionic
Authors: Masaki Tezuka and Antonio M. Garcia-Garcia
Categories: cond-mat.quant-gas cond-mat.dis-nn cond-mat.supr-con
Comments: 5 pages, 5 figures
\\ ( http://arxiv.org/abs/0912.2263 , 21kb)
replaced with revised version Tue, 5 Oct 2010 00:56:45 GMT (1280kb)

Title: Hydrodynamic equation of a spinor dipolar Bose-Einstein condensate
Authors: Kazue Kudo and Yuki Kawaguchi
Categories: cond-mat.quant-gas
Comments: 13 pages, 5 figures
\\ ( http://arxiv.org/abs/1009.1671 , 1280kb)
replaced with revised version Tue, 5 Oct 2010 13:28:25 GMT (5390kb)

Title: Black hole lasers in Bose-Einstein condensates
Authors: Stefano Finazzi and Renaud Parentani
Categories: cond-mat.quant-gas gr-qc
Comments: iopams, 37 pages, 14 figures, 1 table; for associated gif animations,
   see http://people.sissa.it/~finazzi/bec_bhlasers/movies/ or
   http://iopscience.iop.org/1367-2630/12/9/095015/media. Published on New. J.
   Phys. (http://iopscience.iop.org/1367-2630/12/9/095015/). V2: few new
   comments, modified figures
Journal-ref: New J. Phys. 12 (2010) 095015
DOI: 10.1088/1367-2630/12/9/095015
\\ ( http://arxiv.org/abs/1005.4024 , 5390kb)
arXiv:1006.4674 (*cross-listing*)
replaced with revised version Tue, 5 Oct 2010 16:00:19 GMT (412kb,D)

Title: Spin gradient demagnetization cooling of ultracold atoms
Authors: Patrick Medley, David M. Weld, Hirokazu Miyake, David E. Pritchard,
   and Wolfgang Ketterle
Categories: cond-mat.quant-gas physics.atom-ph
Comments: 10 pages, 4 figures; (v3) Added discussion, used updated values of
   scattering lengths
\\ ( http://arxiv.org/abs/1006.4674 , 412kb)
replaced with revised version Tue, 5 Oct 2010 19:09:14 GMT (91kb)

Title: Time-resolved density correlations as probe of squeezing in toroidal
   Bose-Einstein condensates
Authors: Michael Uhlmann
Categories: cond-mat.quant-gas
Comments: 18 pages, IOP style
Journal-ref: New J. Phys. 12 095016 (2010)
DOI: 10.1088/1367-2630/12/9/095016
\\ ( http://arxiv.org/abs/1005.2645 , 91kb)
replaced with revised version Wed, 6 Oct 2010 03:29:10 GMT (271kb)

Title: Linking inverse square law with quantum mechanical probabilities
Authors: Shantilal G. Goradia
Categories: physics.gen-ph
\\ ( http://arxiv.org/abs/physics/0210040 , 271kb)
replaced with revised version Wed, 6 Oct 2010 19:32:53 GMT (320kb)

Title: Cold matter trapping via rotating helical optical potential
Authors: A.Yu.Okulov
Categories: physics.atom-ph cond-mat.quant-gas nlin.PS physics.optics
Comments: 13 pages, 3 figures, submitted to referred journal
\\ ( http://arxiv.org/abs/1005.4213 , 320kb)

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/
Matt's arXiv selection: weekly summary of cold-atom papers from arXiv.org
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Received on Thu Nov 11 2010 - 17:36:56 EST

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