# [Matts-arxiv] Matt's arXiv selection: week ending 4 September 2009

From: Matthew Davis <mdavis_at_physics.uq.edu.au>
Date: Wed, 21 Oct 2009 19:22:27 +1000

Dear subscribers,

This week was compiled by Simon Haine, and contains 30 new abstracts and 12
replacements.

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arXiv:0908.4200
Date: Fri, 28 Aug 2009 12:59:11 GMT (670kb)

Title: Adiabatic transport of Bose-Einstein condensate in double-well trap
Authors: V.O. Nesterenko, A.N. Novikov, A.Yu. Cherny, F.F. de Souza Cruz, and
E. Suraud
Categories: cond-mat.quant-gas cond-mat.other
Comments: 8 pages, 8 figures, submitted to J.Phys.B
\\
A complete irreversible adiabatic transport of Bose-Einstein condensate (BEC)
in a double-well trap is investigated within the mean field approximation. The
transfer is driven by time-dependent (Gaussian) coupling between the wells and
their relative detuning. The protocol successfully works in a wide range of
both repulsive and attractive BEC interaction. The nonlinear effects caused by
the interaction can be turned from detrimental into favorable for the
transport. The results are compared with familiar Landau-Zener scenarios using
the constant coupling. It is shown that the pulsed Gaussian coupling provides a
new transport regime where coupling edges are decisive and convenient switch of
the transport is possible.
\\ ( http://arxiv.org/abs/0908.4200 , 670kb)
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arXiv:0908.4147
Date: Fri, 28 Aug 2009 07:40:10 GMT (163kb)

Title: Experimental comparison of Raman and RF outcouplers for high flux atom
lasers
Authors: J. E. Debs, D. D\"oring, P. A. Altin, C. Figl, J. Dugu\'e, M.
Jeppesen, J. T. Schultz, N. P. Robins, J. D. Close
Categories: quant-ph physics.atom-ph
Comments: 8 Pages, 5 Figures, Submitted to PRA
\\
We study the properties of an atom laser beam derived from a Bose-Einstein
condensate using three different outcouplers, one based on multi-state radio
frequency transitions and two others based on Raman transitions capable of
imparting momentum to the beam. We first summarize the differences that arise
in such systems, and how they may impact on the use of an atom laser in
interferometry. Experimentally, we examine the formation of a bound state in
all three outcouplers, a phenomenon which limits the atom laser flux, and find
that a two-state Raman outcoupler is the preferred option for high flux, low
divergence atom laser beams.
\\ ( http://arxiv.org/abs/0908.4147 , 163kb)
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arXiv:0908.4313
Date: Sat, 29 Aug 2009 02:39:35 GMT (104kb)

Title: Aligned dipolar Bose-Einstein condensate in a double-well potential:
From cigar-shaped to pancake-shaped
Authors: M. Asad-uz-Zaman and D. Blume
Categories: cond-mat.quant-gas
\\
We consider a Bose-Einstein condensate (BEC), which is characterized by
long-range and anisotropic dipole-dipole interactions and vanishing s-wave
scattering length, in a double-well potential. The properties of this system
are investigated as functions of the height of the barrier that splits the
harmonic trap into two halves, the number of particles (or dipole-dipole
strength) and the aspect ratio $\lambda$, which is defined as the ratio between
the axial and longitudinal trapping frequencies $\omega_z$ and $\omega_{\rho}$.
The phase diagram is determined by analyzing the stationary mean-field
solutions. Three distinct regions are found: a region where the energetically
lowest lying stationary solution is symmetric, a region where the energetically
lowest lying stationary solution is located asymmetrically in one of the wells,
and a region where the system is mechanically unstable. For sufficiently large
aspect ratio $\lambda$ and sufficiently high barrier height, the system
consists of two connected quasi-two-dimensional sheets with density profiles
whose maxima are located either at $\rho=0$ or away from $\rho=0$. The
stability of the stationary solutions is investigated by analyzing the
Bogoliubov de Gennes excitation spectrum and the dynamical response to small
perturbations. These studies reveal unique oscillation frequencies and distinct
collapse mechanisms. The results derived within the mean-field framework are
complemented by an analysis based on a two-mode model.
\\ ( http://arxiv.org/abs/0908.4313 , 104kb)
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arXiv:0908.4513
Date: Mon, 31 Aug 2009 12:12:57 GMT (14kb)

Title: Quantum decay of dark solitons in one dimensional Bose systems
Authors: D.M. Gangardt, A. Kamenev
Categories: cond-mat.quant-gas cond-mat.stat-mech
\\
We study dissipative dynamics of a dark soliton at temperatures $T$ lower
than the chemical potential $\mu$ of the background Bose liquid. We show that,
unless the system is integrable, the Raman scattering of phonons leads to a
finite lifetime $\tau\sim (T/\mu)^{-4}$ of the dark soliton. This behavior is
qualitatively different from $\tau\sim (T/\mu)^{-1}$, obtained earlier in the
high temperature regime, and reflects regime of cold'' quantum phonons.
Coherence of such phonons manifests itself in long-range soliton-soliton
\\ ( http://arxiv.org/abs/0908.4513 , 14kb)
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arXiv:0908.4568
Date: Mon, 31 Aug 2009 16:13:17 GMT (321kb)

Title: Creating p-wave superfluids and topological excitations in optical
lattices
Authors: P. Massignan, A. Sanpera, M. Lewenstein
Categories: cond-mat.quant-gas
\\
We propose various optical lattice setups as viable routes towards the
realization of a stable p-wave superfluid. We analyze the vortex excitations on
the lattice with a self-consistent Bogolubov-de Gennes calculation, showing
that the topological zero-energy Majorana mode known to exist in the continuum
survives in the experimentally relevant conditions of finite lattices and
external trapping. Lattice effects are strongest at half-filling: here the
linearity of the low-lying spectrum is lost, and the Majorana mode acquires a
d-wave symmetry, becoming supersolid. When the vortex rotates in the same
direction as the chirality, supersolidity is attained through a quantum phase
transition, over which the Majorana mode changes parity and spreads over the
whole lattice.
\\ ( http://arxiv.org/abs/0908.4568 , 321kb)
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arXiv:0908.4458
Date: Mon, 31 Aug 2009 05:23:02 GMT (256kb)

Title: An exactly solvable phase transition model: generalized statistics and
generalized Bose-Einstein condensation
Authors: Wu-Sheng Dai and Mi Xie
Categories: cond-mat.stat-mech cond-mat.quant-gas
Journal-ref: J. Stat. Mech. (2009) P07034
\\
In this paper, we present an exactly solvable phase transition model in which
the phase transition is purely statistically derived. The phase transition in
this model is a generalized Bose-Einstein condensation. The exact expression of
the thermodynamic quantity which can simultaneously describe both gas phase and
condensed phase is solved with the help of the homogeneous Riemann-Hilbert
problem, so one can judge whether there exists a phase transition and determine
the phase transition point mathematically rigorously. A generalized statistics
in which the maximum occupation numbers of different quantum states can take on
different values is introduced, as a generalization of Bose-Einstein and
Fermi-Dirac statistics.
\\ ( http://arxiv.org/abs/0908.4458 , 256kb)
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arXiv:0908.4583
Date: Mon, 31 Aug 2009 17:11:36 GMT (286kb)

Title: Collective Motion of Polarized Dipolar Fermi Gases in the Hydrodynamic
Regime
Authors: Aristeu R. P. Lima, Axel Pelster
Categories: cond-mat.quant-gas
\\
Recently, a seminal STIRAP experiment allowed the creation of 40K87Rb
molecules in the rovibrational ground state [K.-K. Ni et al., Science 322, 231
(2008)]. In order to describe such a polarized dipolar Fermi gas in the
hydrodynamic regime, we work out a variational time-dependent Hartree-Fock
approach. With this we calculate dynamical properties of such a system as, for
instance, the frequencies of the low-lying excitations and the time-of-flight
expansion. We find remarkable effects of a strong dipole-dipole interaction
such as anisotropic breathing oscillations in momentum space and a suppression
of the aspect-ratio inversion after release of the harmonic trap.
\\ ( http://arxiv.org/abs/0908.4583 , 286kb)
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arXiv:0908.4589
Date: Mon, 31 Aug 2009 18:00:26 GMT (65kb)

Title: Dynamical mean-field theory for light fermion--heavy boson mixtures on
optical lattices
Authors: M. Iskin and J. K. Freericks
Categories: cond-mat.quant-gas cond-mat.str-el
Comments: 10 pages with 4 figures
\\
We theoretically analyze Fermi-Bose mixtures consisting of light fermions and
heavy bosons that are loaded into optical lattices (ignoring the trapping
potential). To describe such mixtures, we consider the Fermi-Bose version of
the Falicov-Kimball model on a periodic lattice. This model can be exactly
mapped onto the spinless Fermi-Fermi Falicov-Kimball model at zero temperature
for all parameter space as long as the mixture is thermodynamically stable. We
employ dynamical mean-field theory to investigate the evolution of the
Fermi-Bose Falicov-Kimball model at higher temperatures. We calculate spectral
moment sum rules for the retarded Green's function and self-energy, and use
them to benchmark the accuracy of our numerical calculations, as well as to
reduce the computational cost by exactly including the tails of infinite
summations or products. We show how the occupancy of the bosons,
single-particle many-body density of states for the fermions, momentum
distribution, and the average kinetic energy evolve with temperature. We end by
briefly discussing how to experimentally realize the Fermi-Bose Falicov-Kimball
model in ultracold atomic systems.
\\ ( http://arxiv.org/abs/0908.4589 , 65kb)
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arXiv:0908.4337
Date: Sat, 29 Aug 2009 17:07:26 GMT (535kb)

Title: Deterministic generation of non-classical states of light using photon
Authors: Andrei Faraon, Arka Majumdar and Jelena Vuckovic
Categories: quant-ph
\\
The generation of non-classical states of light via photon blockade with
time-modulated input is analyzed. We show that improved single photon
statistics can be obtained by adequately choosing the parameters of the driving
laser pulses. An alternative method, where the system is driven via a
continuous wave laser and the frequency of the dipole is controlled (e.g.
electrically) at very fast timescales is presented.
\\ ( http://arxiv.org/abs/0908.4303 , 535kb)
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arXiv:0908.4337
Date: Sat, 29 Aug 2009 17:07:26 GMT (1494kb)

Title: Some entanglement features of three-atoms Tavis-Cummings model:
Cooperative case
Authors: M. Youssef, A.-S. F. Obada and N. Metwally
Categories: quant-ph
\\
In this paper we consider a system of identical three two-level atoms
interacting at resonance with a single-mode of the quantized field in a
lossless cavity. The initial cavity field is prepared in the coherent state
while the atoms are taken initially to be either in the uppermost excited state
"$|eee>$" or The $\textmd{GHZ}$-state or the $\textmd{W}$-state. For this
system we investigate different kinds of atomic inversion and entanglement,
which arise between the different parts of the system due to the interaction.
Also the relationship, between entanglement and some other nonclassical effects
in the statistical properties, such as collapses and revivals in the atomic
inversion where superharmonic effects appear, is discussed. The $Q$-functions
for different cases are discussed. Most remarkably it is found that the
$\textmd{GHZ}$-state is more robust against energy losses, showing almost
coherent trapping and Schr\"odinger-cat states can not be produced from such
state. Also the entanglement of $\textmd{GHZ}$-state is more robust than the
$\textmd{W}$-state. Another interesting feature found is that the state which
has no pairwise entanglement initially will have a much improvement of such
pairwise entanglement through the evolution. Sudden death and sudden revival of
atoms-pairwise entanglement are produced with the $\textmd{W}$-state.
\\ ( http://arxiv.org/abs/0908.4337 , 1494kb)
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arXiv:0908.4348
Date: Sat, 29 Aug 2009 17:07:26 GMT (314kb)

Title: Relational Blockworld Interpretation of Quantum Field Theory
Authors: W.M. Stuckey, Timothy McDevitt and Michael Silberstein
Categories: quant-ph
Comments: 38 pages text, 8 figures
\\
We propose a new interpretation of quantum field theory (QFT) based on our
interpretation of non-relativistic quantum mechanics called Relational
Blockworld. In our interpretation, QFT is the continuous approximation of a
more fundamental, discrete theory whereby the transition amplitude Z is not
viewed as a sum over all paths in configuration space, but is a mathematical
machine for measuring the symmetry of the differential operator and source
vector of the discrete action in determining the relative locations of
individual detector clicks. We propose that the differential operator and
source vector of the underlying discrete theory are related via a
self-consistency criterion (SCC) based on a discrete counterpart to the
identity that underwrites divergence-free sources in classical field theory,
i.e., the boundary of a boundary is zero. Thereby Z is constructed from the
SCC, rather than classical field theory, and QFT is the continuous
approximation using trajectories, rather than individual detector clicks, as
the fundamental entities. In order to illustrate this interpretation, we
construct a candidate for the SCC using a discrete path integral formalism over
graphs. In this specific approach, the SCC is a tautology, based on the
boundary of a boundary is zero, that ensures the source vector is
divergence-free and resides in the row space of the differential operator.
Accordingly, the differential operator will necessarily have an eigenvector
with eigenvalue zero, so the SCC is the origin of gauge invariance. Using this
formalism, we obtain the two-source transition amplitude over a
(1+1)-dimensional graph with N vertices fundamental to the scalar Gaussian
theory.
\\ ( http://arxiv.org/abs/0908.4348 , 314kb)
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arXiv:0908.4473
Date: Mon, 31 Aug 2009 08:21:21 GMT (169kb)

Title: Unequal intensity splitting can reduce back action in interferometers
Authors: Ole Steuernagel
Categories: quant-ph
\\
Typical two-path interferometers are intensity-balanced because this
maximizes the visibility of their interference patterns. Unbalancing the
interferometer can be advised when back action on the object whose position is
monitored is to be reduced. Variations of the intensity splitting ratios in
two-path interferometers are analyzed in order to determine optimal
interferometric performance while minimizing back action: it turns out that
homodyning-like schemes perform best.
\\ ( http://arxiv.org/abs/0908.4473 , 169kb)
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arXiv:0908.4475
Date: Mon, 31 Aug 2009 08:26:26 GMT (773kb)

Title: Multi-barrier resonant tunneling for the one-dimensional nonlinear
Schr\"odinger Equation
Authors: K Rapedius and H J Korsch
Categories: quant-ph
\\
For the stationary one-dimensional nonlinear Schr\"odinger equation (or
Gross-Pitaevskii equation) nonlinear resonant transmission through a finite
number of equidistant identical barriers is studied using a (semi-) analytical
approach. In addition to the occurrence of bistable transmission peaks known
from nonlinear resonant transmission through a single quantum well
(respectively a double barrier) complicated (looped) structures are observed in
the transmission coefficient which can be identified as the result of symmetry
breaking similar to the emergence of self-trapping states in double well
potentials. Furthermore it is shown that these results are well reproduced by a
nonlinear oscillator model based on a small number of resonance eigenfunctions
of the corresponding linear system.
\\ ( http://arxiv.org/abs/0908.4475 , 773kb)
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arXiv:0908.4444
Date: Tue, 1 Sep 2009 14:40:27 GMT (348kb)

Title: Upper Limit on the Magnetic Dipole Contribution to the 5p-8p Transition
in Rb by Use of Ultracold Atom Spectroscopy
Authors: R. Pires, M. Ascoli, E. E. Eyler, P. L. Gould, and A. Derevianko
Categories: physics.atom-ph
Comments: 7 pages, 4 figures, 3 tables
\\
We report on hyperfine-resolved spectroscopic measurements of the
electric-dipole forbidden 5$p_{3/2} \to 8p_{1/2}$ transition in a sample of
ultracold $^{87}$Rb atoms. The hyperfine selection rules enable the weak
magnetic-dipole (M1) contribution to the transition strength to be
distinguished from the much stronger electric-quadrupole (E2) contribution. An
upper limit on the M1 transition strength is determined that is about 50 times
smaller than an earlier experimental determination. We also calculate the
expected value of the M1 matrix element and find that it is less than the upper
limit extracted from the experiment.
\\ ( http://arxiv.org/abs/0908.4444 , 348kb)
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arXiv:0909.0195
Date: Tue, 1 Sep 2009 14:40:27 GMT (696kb)

Title: Interaction-induced dynamical phase locking of Bose-Einstein condensates
Authors: Erez Boukobza, Doron Cohen, and Amichay Vardi
Categories: cond-mat.quant-gas
\\
We show that interactions result in the emergence of a {\it definite}
relative-phase between two initially incoherent Bose-Einstein condensates. The
many-realization interference fringe visibility is universal at
$g_{12}^{(1)}\sim1/3$ throughout the Josephson interaction regime, as evident
from a semiclassical picture. Other types of incoherent preparation yield
qualitatively different coherence dynamics.
\\ ( http://arxiv.org/abs/0909.0195 , 696kb)
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arXiv:0909.0102
Date: Tue, 1 Sep 2009 19:55:51 GMT (117kb)

Title: Double diffraction in an atomic gravimeter
Authors: Nicola Malossi (SYRTE), Quentin Bodart (SYRTE), S\'ebastien Merlet
(SYRTE), Arnaud Landragin (SYRTE), Franck Pereira Dos Santos (SYRTE)
Categories: physics.atom-ph
\\
We demonstrate the realization of a new scheme for cold atom gravimetry based
on the use of double diffraction beamsplitters recently demonstrated in
\cite{Leveque}, where the use of two retro-reflected Raman beams allows
symmetric diffraction in $\pm \hbar k_{eff}$ momenta. Though in principle
restricted to the case of zero Doppler shift, for which the two pairs of Raman
beams are simultaneously resonant, we demonstrate that such diffraction pulses
can remain efficient on atoms with non zero velocity, such as in a gravimeter,
when modulating the frequency of one of the two Raman laser sources. We use
such pulses to realize an interferometer insensitive to laser phase noise and
some of the dominant systematics. This reduces the technical requirements and
would allow the realization of a simple atomic gravimeter. We demonstrate a
sensitivity of $1.2\times10^{-7}g$ per shot.
\\ ( http://arxiv.org/abs/0909.0102 , 117kb)
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arXiv:0909.0249
Date: Tue, 1 Sep 2009 19:55:51 GMT (1051kb)

Title: Large spin relaxation rates in trapped submerged-shell atoms
Authors: Colin B. Connolly, Yat Shan Au, S. Charles Doret, Wolfgang Ketterle,
John M. Doyle
Categories: physics.atom-ph
\\
Spin relaxation due to atom-atom collisions is measured for magnetically
trapped erbium and thulium atoms at a temperature near 500 mK. The rate
constants for Er-Er and Tm-Tm collisions are 3.0 times 10^-10 cm^3 s^-1 and 1.1
times 10^-10 cm^3 s^-1, respectively, 2-3 orders of magnitude larger than those
observed for highly magnetic S-state atoms. This is strong evidence for an
additional, dominant, spin relaxation mechanism, electrostatic anisotropy, in
collisions between these "submerged-shell" L > 0 atoms. These large spin
relaxation rates imply that evaporative cooling of these atoms in a magnetic
trap will be highly inefficient.
\\ ( http://arxiv.org/abs/0909.0249 , 1051kb)
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arXiv:0909.0416
Date: Wed, 2 Sep 2009 15:31:28 GMT (3637kb)

Title: Functional renormalization and ultracold quantum gases
Authors: S. Floerchinger
Categories: cond-mat.quant-gas
Comments: doctoral thesis, 187 pages, 60 figures
\\
The method of functional renormalization is applied to the theoretical
investigation of ultracold quantum gases. Flow equations are derived for a Bose
gas with approximately pointlike interaction, for a Fermi gas with two
(hyperfine) spin components in the Bardeen-Cooper-Schrieffer (BCS) to
Bose-Einstein condensation (BEC) crossover and for a Fermi gas with three
components. The solution of the flow equations determine the properties of
these systems both in the few-body regime and in thermal equilibrium.
For the Bose gas this covers the quantum phase diagram, the condensate and
superfluid fraction, the critical temperature, the correlation length, the
specific heat or sound propagation. The properties are discussed both for three
and two spatial dimensions. The discussion of the Fermi gas in the BCS-BEC
crossover concentrates on the effect of particle-hole fluctuations but
addresses the complete phase diagram. For the three component fermions, the
flow equations in the few-body regime show a limit-cycle scaling and the Efimov
tower of three-body bound states. Applied to the case of Lithium they explain
recently observed three-body loss features. Extending the calculations by
continuity to nonzero density, it is found that a new trion phase separates a
BCS and a BEC phase for three component fermions close to a common resonance.
More formal is the derivation of a new exact flow equation for scale
dependent composite operators. This equation allows for example a better
treatment of bound states.
\\ ( http://arxiv.org/abs/0909.0416 , 3637kb)
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arXiv:0909.0489
Date: Wed, 2 Sep 2009 18:24:16 GMT (1515kb)

Title: Spin-dependent inelastic collisions in spin-2 Bose-Einstein condensates
Authors: Satoshi Tojo, Taro Hayashi, Tatsuyoshi Tanabe, Takuya Hirano, Yuki
Kawaguchi, Hiroki Saito, and Masahito Ueda
Categories: cond-mat.quant-gas
\\
We studied spin-dependent two-body inelastic collisions in F=2 87Rb
Bose-Einstein condensates both experimentally and theoretically. The 87Rb
condensates were confined in an optical trap and selectively prepared in
various spin states in the F=2 manifold at a magnetic field of 3.0 G. Measured
atom loss rates are found to depend on spin states of colliding atoms. We
measured two fundamental loss coefficients for two-body inelastic collisions
with the total spin of 0 and 2; the coefficients determine loss rates for all
the spin pairs. The experimental results for mixtures of all the spin
combinations are in good agreement with numerical solutions of the
Gross-Pitaevskii equations that include the effect of a magnetic field
\\ ( http://arxiv.org/abs/0909.0489 , 1515kb)
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arXiv:0909.0491
Date: Wed, 2 Sep 2009 19:18:46 GMT (2783kb)

Title: Light scattering for thermometry of fermionic atoms in an optical
lattice
Authors: J. Ruostekoski, C. J. Foot, and A. B. Deb
Categories: cond-mat.quant-gas
Comments: submitted to PRL in January 2009
\\
We propose a method for measuring the temperature of fermionic atoms in an
optical lattice potential from the intensity of the scattered light in the
far-field diffraction pattern. We consider a single-component gas in a
tightly-confined two-dimensional lattice, illuminated by far off-resonant light
driving a cycling transition. Our calculations show that thermal correlations
of the fermionic atoms generate fluctuations in the intensity of the
diffraction pattern of light scattered from the atomic lattice array and that
this signal can be accurately detected above the shot noise using a lens to
collect photons scattered in a forward direction (with the diffraction maxima
blocked). The sensitivity of the thermometer is enhanced by an additional
harmonic trapping potential.
\\ ( http://arxiv.org/abs/0909.0491 , 2783kb)
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arXiv:0909.0311
Date: Wed, 2 Sep 2009 03:42:46 GMT (150kb)

Title: Revival-collapse phenomenon in the quadrature squeezing of the
multiphoton intensity-dependent Jaynes-Cummings model
Authors: Faisal A A El-Orany
Categories: quant-ph
Journal-ref: J. Mod. Opt. 53 (2006) 1699-1714
\\
For multiphoton intensity-dependent Jaynes-Cummings model (JCM), which is
described by two-level atom interacting with a radiation field, we prove that
there is a relationship between the atomic inversion and the quadrature
squeezing. We give the required condition to obtain best information from this
relation. Also we show that this relation is only sensitive to large values of
the detuning parameter. Furthermore, we discuss briefly such relation for the
off-resonance standard JCM.
\\ ( http://arxiv.org/abs/0909.0311 , 150kb)
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arXiv:0909.0728
Date: Thu, 3 Sep 2009 19:56:49 GMT (213kb,D)

Title: Simulating and detecting artificial magnetic fields in trapped atoms
Authors: Matthias Rosenkranz, Alexander Klein, Dieter Jaksch
Categories: cond-mat.quant-gas cond-mat.other
\\
A Bose-Einstein condensate exhibiting a nontrivial phase induces an
artificial magnetic field in immersed impurity atoms trapped in a stationary,
ring-shaped optical lattice. We present an effective Hamiltonian for the
impurities for two condensate setups: the condensate in a rotating ring and in
an excited rotational state in a stationary ring. We use Bogoliubov theory to
derive analytical formulas for the induced artificial magnetic field and the
hopping amplitude in the limit of low condensate temperature where the impurity
dynamics is coherent. As methods for observing the artificial magnetic field we
discuss time of flight imaging and mass current measurements. Moreover, we
compare the analytical results of the effective model to numerical results of a
corresponding two-species Bose-Hubbard model. We also study numerically the
clustering properties of the impurities and the quantum chaotic behavior of the
two-species Bose-Hubbard model.
\\ ( http://arxiv.org/abs/0909.0728 , 213kb)
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arXiv:0909.0536
Date: Wed, 2 Sep 2009 22:00:08 GMT (149kb)

Title: Variational ansatz for the nonlinear Landau-Zener problem for cold atom
association
Authors: A. Ishkhanyan, B. Joulakian, and K.-A. Suominen
Categories: cond-mat.quant-gas
\\
We present a rigorous analysis of the Landau-Zener linear-in-time term
crossing problem for quadratic-nonlinear systems relevant to the coherent
association of ultracold atoms in degenerate quantum gases. Our treatment is
based on an exact third-order nonlinear differential equation for the molecular
state probability. Applying a variational two-term ansatz we construct a simple
approximation that accurately describes the whole time dynamics of coupled
atom-molecular system for any set of involved parameters. Assuring an absolute
error less than for the final transition probability, the resultant solution
improves, by several orders of magnitude, the accuracy of the previous
approximations by A. Ishkhanyan et al. developed separately for the weak
coupling [J. Phys. A 38, 3505 (2005)] and strong interaction [J. Phys. A 39,
14887 (2006)] limits. In addition, the constructed approximation covers the
whole moderate coupling regime providing for this intermediate regime the same
accuracy as for the two mentioned limits. The obtained results reveal a
remarkable observation that for the strong coupling limit the resonance
crossing is mostly governed by the nonlinearity while the coherent
atom-molecular oscillations coming up soon after the resonance has been crossed
are basically of linear nature. This observation is supposed to be of general
character due to the basic attributes of the resonance crossing processes in
the nonlinear quantum systems of the discussed type of involved quadratic
nonlinearity.
\\ ( http://arxiv.org/abs/0909.0536 , 149kb)
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arXiv:0909.0565
Date: Thu, 3 Sep 2009 03:37:26 GMT (693kb)

Title: Magnetic Crystallization of a Ferromagnetic Bose-Einstein Condensate
Authors: Yuki Kawaguchi, Hiroki Saito, Kazue Kudo, and Masahito Ueda
Categories: cond-mat.quant-gas
\\
We use mean-field theory to show that magnetic crystallization emerges in a
spin-1 ferromagnetic Bose-Einstein condensate with magnetic dipole-dipole
interaction. The periodicity of the checkerboard pattern is about three times
as large as that observed by the Berkeley group [Phys. Rev. Lett. {\bf 100},
170403 (2008)], and the pattern eventually dissolves. The stationary spin
configuration of the system is determined by the interplay between the dipole
interaction and the quadratic Zeeman effect.
\\ ( http://arxiv.org/abs/0909.0565 , 693kb)
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arXiv:0909.0652
Date: Thu, 3 Sep 2009 13:47:04 GMT (229kb)

Title: Spinor BECs in a double-well: population transfer and Josephson
oscillations
Authors: B. Julia-Diaz, M. Mele-Messeguer, M. Guilleumas, A. Polls
Categories: cond-mat.other cond-mat.quant-gas
\\
The dynamics of an F=1 spinor condensate in a two-well potential is studied
within the framework of the Gross-Pitaevskii equation. We derive two-mode
equations relating the population imbalances, the phase differences among the
condensates at each side of the barrier and the time evolution of the different
Zeeman populations for the case of small population imbalances. The case of
zero total magnetization is scrutinized in this limit demonstrating the ability
of a two mode analysis to describe to a large extent the dynamics observed in
the Gross-Pitaevskii equations. It is also demonstrated that the time evolution
of the different total populations fully decouples from the Josephson tunneling
phenomena. All the relevant time scales are clearly identified with microscopic
properties of the atom-atom interactions.
\\ ( http://arxiv.org/abs/0909.0652 , 229kb)
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arXiv:0909.0678
Date: Thu, 3 Sep 2009 15:05:19 GMT (1436kb,D)

Title: Microwave Control of Atomic Motion in Optical Lattices
Authors: Leonid F\"orster, Micha{\l} Karski, Jai-Min Choi, Andreas Steffen,
Wolfgang Alt, Dieter Meschede, Artur Widera, Enrique Montano, Jae Hoon Lee,
Worawarong Rakreungdet and Poul S. Jessen
Categories: quant-ph physics.atom-ph
\\
We control the quantum mechanical motion of neutral atoms in an optical
lattice by driving microwave transitions between spin states whose trapping
potentials are spatially offset. Control of this offset with nanometer
precision allows for adjustment of the coupling strength between different
motional states, analogous to an adjustable effective Lamb-Dicke factor. This
is used both for efficient one-dimensional sideband cooling of individual atoms
to a vibrational ground state population of 97%, and to drive coherent Rabi
oscillation between arbitrary pairs of vibrational states. We further show that
microwaves can drive well resolved transitions between motional states in
maximally offset, shallow lattices, and thus in principle allow for coherent
control of long range quantum transport.
\\ ( http://arxiv.org/abs/0909.0678 , 1436kb)
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\\
arXiv:0909.0705
Date: Thu, 3 Sep 2009 16:27:14 GMT (18kb)

Title: Rabi Interferometry and Sensitive Measurement of the Casimir-Polder
Force with Ultra-Cold Gases
Authors: Jan Chwede\'nczuk, Luca Pezz\'e, Francesco Piazza and Augusto Smerzi
Categories: quant-ph
\\
We show that Rabi oscillations of a degenerate fermionic or bosonic gas
trapped in a double-well potential can be exploited for the interferometric
measurement of external forces at micrometer length scales. The Rabi
interferometer is less sensitive, but easier to implement, than the
Mach-Zehnder since it does not require dynamical beam-splitting/recombination
processes. As an application we propose a measurement of the Casimir-Polder
force acting between the atoms and a dielectric surface. We find that even if
the interferometer is fed with a coherent state of relatively small number of
atoms, and in the presence of realistic experimental noise, the force can be
measured with a sensitivity sufficient to discriminate between thermal and
zero-temperature regimes of the Casimir-Polder potential. Higher sensitivities
can be reached with spin squeezed states.
\\ ( http://arxiv.org/abs/0909.0705 , 18kb)
------------------------------------------------------------------------------

Some obscure but interesting ones:

------------------------------------------------------------------------------
\\
arXiv:0908.4464 (*cross-listing*)
Date: Mon, 31 Aug 2009 06:27:46 GMT (1898kb)

Title: The eel-like robot
Authors: Fr\'ed\'eric Boyer (IRCCyN), Damien Chablat (IRCCyN), Philippe Lemoine
(IRCCyN), Philippe Wenger (IRCCyN)
Categories: cs.RO physics.class-ph
Journal-ref: ASME Design Engineering Technical Conferences, San Diego : United
States (2009)
\\
The aim of this project is to design, study and build an "eel-like robot"
prototype able to swim in three dimensions. The study is based on the analysis
of eel swimming and results in the realization of a prototype with 12
vertebrae, a skin and a head with two fins. To reach these objectives, a
multidisciplinary group of teams and laboratories has been formed in the
framework of two French projects.
\\ ( http://arxiv.org/abs/0908.4464 , 1898kb)
------------------------------------------------------------------------------
\\
arXiv:0909.0084
Date: Tue, 1 Sep 2009 04:07:41 GMT (377kb)

Title: Revisiting Pollock's Drip Paintings
Authors: Katherine Jones-Smith, Harsh Mathur
Categories: physics.soc-ph
Comments: Appeared in Nature Nov.2006. Previously unavailable on arxiv. Figures
here are low resolution version
Journal-ref: Nature 444, E9-E10 (30 November 2006)
\\
We investigate the contentions that Jackson Pollock's drip paintings are
fractals produced by the artist's Levy distributed motion and that fractal
analysis may be used to authenticate works of uncertain provenance[1-5]. We
find that the paintings exhibit fractal characteristics over too small a range
to be usefully considered as fractal; their limited fractal characteristics are
easily generated without Levy motion, both by freehand drawing and gaussian
random motion. Several problems must therefore be addressed before fractal
analysis can be used to authenticate paintings.
\\ ( http://arxiv.org/abs/0909.0084 , 377kb)
------------------------------------------------------------------------------
\\
arXiv:0908.4349 (*cross-listing*)
Date: Sat, 29 Aug 2009 17:28:06 GMT (197kb)

Title: Scientific Understanding and the Risk from Extreme Space Weather
Authors: Mike Hapgood
Categories: physics.space-ph physics.plasm-ph physics.soc-ph
\\
Like all natural hazards, space weather exhibits occasional extreme events
over timescales of decades to centuries. Historical events provoked much
advanced technological infrastructures over the past fifty years gives these
events the potential to disrupt those infrastructures - and thus create
profound economic and societal impact. However, like all extreme hazards, such
events are rare, so we have limited data on which to build our understanding of
the events. Many other natural hazards (e.g. flash floods) are highly
localised, so statistically significant datasets can be assembled by combining
data from independent instances of the hazard recorded over a few decades. But
we have a single instance of space weather so we would have to make
observations for many centuries in order to build a statistically significant
dataset. Instead we must exploit our knowledge of solar-terrestrial physics to
find other ways to assess these risks. We discuss three alternative approaches:
(a) use of proxy data, (b) studies of other solar systems, and (c) use of
physics-based modelling. The proxy data approach is well-established as a
technique for assessing the long-term risk from radiation storms, but does not
yet provide any means to assess the risk from severe geomagnetic storms. This
latter risk is more suited to the other approaches. We need to develop and
expand techniques to monitoring key space weather features in other solar
systems. To make progress in modelling severe space weather, we need to focus
on the physics that controls severe geomagnetic storms, e.g. how can dayside
and tail reconnection be modulated to expand the region of open flux to envelop
mid-latitudes?
\\ ( http://arxiv.org/abs/0908.4349 , 197kb)
------------------------------------------------------------------------------

The replacements:

------------------------------------------------------------------------------
\\
arXiv:0709.3740
replaced with revised version Fri, 28 Aug 2009 19:03:01 GMT (1273kb)

Title: Staggered-Vortex Superfluid of Ultracold Bosons in an Optical Lattice
Authors: Lih-King Lim, C. Morais Smith, Andreas Hemmerich
Categories: cond-mat.quant-gas cond-mat.other cond-mat.supr-con
Journal-ref: Phys. Rev. Lett. 100, 130402 (2008)
\\ ( http://arxiv.org/abs/0709.3740 , 1273kb)
------------------------------------------------------------------------------
\\
arXiv:0804.2600
replaced with revised version Fri, 28 Aug 2009 17:53:58 GMT (407kb)

Title: Correlation Effects in Ultracold Two-Dimensional Bose Gases
Authors: Lih-King Lim, C. Morais Smith, and H. T. C. Stoof
Categories: cond-mat.stat-mech
Journal-ref: Phys. Rev. A 78, 013634 (2008)
\\ ( http://arxiv.org/abs/0804.2600 , 407kb)
------------------------------------------------------------------------------
\\
arXiv:0905.1281
replaced with revised version Fri, 28 Aug 2009 17:40:26 GMT (2517kb)

Title: Strongly Interacting Two-Dimensional Dirac Fermions
Authors: Lih-King Lim, Achilleas Lazarides, Andreas Hemmerich, and C. Morais
Smith
Categories: cond-mat.quant-gas cond-mat.supr-con
\\ ( http://arxiv.org/abs/0905.1281 , 2517kb)
------------------------------------------------------------------------------
\\
arXiv:0902.2275
replaced with revised version Mon, 31 Aug 2009 11:31:34 GMT (443kb,D)

Title: Angular FFLO State in Cold Fermion Gases in Toroidal Trap
Authors: Youichi Yanase
Categories: cond-mat.other cond-mat.supr-con
\\ ( http://arxiv.org/abs/0902.2275 , 443kb)
------------------------------------------------------------------------------
\\
arXiv:0908.3356
replaced with revised version Sun, 30 Aug 2009 11:42:49 GMT (1539kb)

Title: Quantum Information Approach to Rotating Bose-Einstein Condensate
Authors: Zhao Liu, Hongli Guo, Shu Chen and Heng Fan
Categories: cond-mat.quant-gas quant-ph
\\ ( http://arxiv.org/abs/0908.3356 , 1539kb)
-----------------------------------------------------------------------------
\\
arXiv:0904.0995
replaced with revised version Mon, 31 Aug 2009 02:06:35 GMT (1019kb)

Title: Drag force on an impurity below the superfluid critical velocity in a
quasi-one-dimensional Bose-Einstein condensate
Authors: Andrew G. Sykes, Matthew J. Davis, and David C. Roberts
Categories: cond-mat.quant-gas
Comments: 7 pages (including supplementary material)
Journal-ref: Phys. Rev. Lett. 103, 085302 (2009)
\\ ( http://arxiv.org/abs/0904.0995 , 1019kb)
------------------------------------------------------------------------------
\\
arXiv:0904.2881
replaced with revised version Sat, 29 Aug 2009 17:48:50 GMT (1947kb)

Title: A supercritical superfluid and vortex unbinding following a quantum
quench
Authors: L. Mathey, A. Polkovnikov
Categories: cond-mat.quant-gas
\\ ( http://arxiv.org/abs/0904.2881 , 1947kb)
------------------------------------------------------------------------------
\\
arXiv:0904.3738
replaced with revised version Mon, 31 Aug 2009 11:10:57 GMT (476kb)

Title: p-Wave Resonant Bose Gas: A Finite-Momentum Spinor Superfluid
Categories: cond-mat.quant-gas cond-mat.other
Comments: updated version published in PRL, with minor typos corrected
Journal-ref: Phys. Rev. Lett. 103, 095302 (2009)
\\ ( http://arxiv.org/abs/0904.3738 , 476kb)
------------------------------------------------------------------------------
\\
arXiv:0905.3420
replaced with revised version Mon, 31 Aug 2009 07:08:07 GMT (286kb)

Title: Photon wave function and zitterbewegung
Authors: Zhi-Yong Wang, Cai-Dong Xiong, Qi Qiu
Categories: quant-ph
\\ ( http://arxiv.org/abs/0905.3420 , 286kb)
-----------------------------------------------------------------------------
\\
arXiv:0908.0248
replaced with revised version Wed, 2 Sep 2009 07:59:51 GMT (147kb)

Title: Bose-Einstein condensation of alkaline earth atoms: $^{40}${Ca}
Authors: Sebastian Kraft, Felix Vogt, Oliver Appel, Fritz Riehle, and Uwe Sterr
Categories: cond-mat.quant-gas physics.atom-ph
\\ ( http://arxiv.org/abs/0908.0248 , 147kb)
------------------------------------------------------------------------------
\\
arXiv:0810.1965
replaced with revised version Thu, 3 Sep 2009 17:54:37 GMT (183kb)

Title: Coherent Atom-Molecule Oscillations in a Bose-Fermi Mixture
Authors: M. L. Olsen, J. D. Perreault, T. D. Cumby, and D. S. Jin
Categories: cond-mat.other
Journal-ref: Phys. Rev. A 80, 030701(R) (2009)
\\ ( http://arxiv.org/abs/0810.1965 , 183kb)
------------------------------------------------------------------------------
\\
arXiv:gr-qc/0506108 (*cross-listing*)
replaced with revised version Thu, 3 Sep 2009 09:31:20 GMT (18kb)

Title: Dark energy from quantum wave function collapse of dark matter
Authors: A. S. Majumdar, D. Home, S. Sinha
Categories: gr-qc quant-ph
Comments: 5 pages in Elsevier style to match with version published in Phys.
Lett. B
Journal-ref: Phys. Lett. B 679 (2009) 167
\\ ( http://arxiv.org/abs/gr-qc/0506108 , 18kb)
------------------------------------------------------------------------------

Till next time,
Matt.

--
=========================================================================
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
http://www.physics.uq.edu.au/people/mdavis/matts_arXiv/
=========================================================================
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=========================================================================
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Received on Fri Nov 20 2009 - 18:54:59 EST

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