Matt's arXiv selection: week ending 12 December 2008

From: Matthew Davis <>
Date: Mon, 12 Jan 2009 09:42:15 +1000

The following message was sent to the matts_arxiv list by Matthew Davis <>

Hi all,

To get the week started, here is another 37 new preprints and 23 replacements
from December.

Date: Fri, 5 Dec 2008 19:13:26 GMT (198kb)

Title: Three-body loss in lithium from functional renormalization
Authors: R. Schmidt, S. Floerchinger, and C. Wetterich
Categories: cond-mat.other
Comments: 4 pages, 4 figures
   We use functional integral methods for an estimate of the three-body loss in
a three-component $^6$Li ultracold atom gas. We advocate a simple picture where
the loss proceeds by the formation of a three-atom bound state, the trion. In
turn, the effective amplitude for the trion formation from three atoms is
estimated from a simple effective boson exchange process. The energy gap of the
trion and other key quantities for the loss coefficient are computed in a
functional renormalization group framework.
\\ ( , 198kb)
Date: Fri, 5 Dec 2008 19:37:33 GMT (569kb)

Title: Phase-diffusion dynamics in weakly coupled Bose-Einstein condensates
Authors: Erez Boukobza, Maya Chuchem, Doron Cohen, and Amichay Vardi
Categories: cond-mat.other
Comments: 5 pages, 4 figures
   We study the phase-sensitivity of collisional phase-diffusion between weakly
coupled Bose-Einstein condensates, using a semiclassical picture of the
two-mode Bose-Hubbard model. When weak-coupling is allowed, zero relative phase
locking is attained in the Josephson-Fock transition regime, whereas a $\pi$
relative phase is only locked in Rabi-Josephson point. Our analytic
semiclassical estimates agree well with the numerical results.
\\ ( , 569kb)
arXiv:0812.0883 (*cross-listing*)
Date: Thu, 4 Dec 2008 09:13:16 GMT (21kb)

Title: Quantum Monte Carlo method applied to strongly correlated dilute fermi
   gases with finite effective range
Authors: G. Wlazlowski, P. Magierski
Categories: nucl-th cond-mat.stat-mech
Comments: 7 pages, 1 figure, proceedings from XIV Nuclear Physics Workshop in
   Kazimierz Dolny, Poland
   We discuss the Auxiliary Field Quantum Monte Carlo (AFQMC) method applied to
dilute neutron matter at finite temperatures. We formulate the discrete
Hubbard-Stratonovich transformation for the interaction with finite effective
range which is free from the sign problem. The AFQMC results are compared with
those obtained from exact diagonalization for a toy model. Preliminary
calculations of energy and chemical potential as a function of temperature are
\\ ( , 21kb)
Date: Fri, 5 Dec 2008 01:35:26 GMT (110kb)

Title: Pure Quantum Correlations Between Bright Optical Beams
Authors: Yana Shang, Zhihui Yan, Xiaojun Jia, Xiaolong Su, Changde Xie, and
   Kunchi Peng
Categories: quant-ph
   The pure quantum correlations totally independent of the classical coherence
of light have been experimentally demonstrated. By measuring the visibility of
the interference fringes and the correlation variances of amplitude and phase
quadratures between a pair of bright twin optical beams with different
frequencies produced from a non-degenerate optical parametric oscillator, we
found that when classical interference became worse even vanished, the
quadrature quantum correlations were not influenced, completely. The presented
experiment obviously shows the quantum correlations of light do not necessarily
imply the classical coherence.
\\ ( , 110kb)
Date: Fri, 5 Dec 2008 14:03:45 GMT (3020kb)

Title: Sympathetically cooled molecular ions: from principles to first
Authors: Bernhard Roth, Stephan Schiller
Categories: quant-ph
Comments: 52 pages, 41 figures; to appear in "Cold Molecules", R. Krems, B.
   Friedrich, and W. Stwalley, eds., Taylor and Francis (2009)
   We review the current status of the field of sympathetically cooled molecular
ions, i.e. the method used for cooling the translational degrees of freedom,
the techniques applied for detection and analysis of the cold trapped ion
ensembles produced as well as first applications. We summarize a few salient
results and point out various possibilities for future developments.
\\ ( , 3020kb)
Date: Fri, 5 Dec 2008 19:52:15 GMT (242kb)

Title: Transient dynamics and momentum redistribution in cold atoms via
   recoil-induced resonances
Authors: Joel A. Greenberg and Daniel J. Gauthier
Categories: quant-ph
Comments: 7 pages, 6 figures
   We use an optically dense, anisotropic magneto-optical trap to study
recoil-induced resonances (RIRs) in the transient, high-gain regime. We find
that two distinct mechanisms govern the atomic dynamics: the finite,
frequency-dependent atomic response time, and momentum-space population
redistribution. At low input probe intensities, the residual Doppler width of
the atoms, combined with the finite atomic response time, result in a linear,
transient hysteretic effect that modifies the locations, widths, and magnitudes
of the resulting gain spectra depending on the sign of the scan chirp. When
larger intensities (\textit{i.e.}, greater than a few $\mu$W/cm$^2$) are
incident on the atomic sample for several $\mu$s, hole-burning in the atomic
sample's momentum distribution leads to a coherent population redistribution
that persists for approximately 100 $\mu$s. We propose using RIRs to engineer
the atomic momentum distribution to enhance the nonlinear atom-photon coupling.
We present a numerical model, and compare the calculated and experimental
results to verify our interpretation.
\\ ( , 242kb)
arXiv:0812.0815 (*cross-listing*)
Date: Wed, 3 Dec 2008 21:07:07 GMT (284kb)

Title: Fermion induced superfluid decoherence in the boson Hubbard model on an
   optical lattice
Authors: Roman M. Lutchyn, Sumanta Tewari, S. Das Sarma
Categories: cond-mat.str-el quant-ph
Comments: 4 pages, 1 eps figure
   We study the phase diagram of a degenerate gas of bosons in an optical
lattice, described by the boson Hubbard Hamiltonian, interacting with
spin-polarized fermions. Virtual transitions of the bosons to the higher Bloch
bands, coupled with the contact interspecies interactions of either sign,
result in an effective increase of the bosonic on-site repulsion. If this
renormalization of the on-site potential is dominant over the fermionic
screening of the boson interactions, superfluid coherence of the Bose-Hubbard
system will be reduced by the fermions. We discuss experimental implications
for cold atomic systems.
\\ ( , 284kb)
Date: Sat, 6 Dec 2008 11:14:26 GMT (883kb)

Title: Ground state properties of a Tonks-Girardeau Gas in a periodic potential
Authors: Bo-Bo Wei, Shi-Jian Gu and Hai-Qing Lin
Categories: cond-mat.stat-mech cond-mat.mes-hall
Comments: 7 pages
   In this paper, we investigate the ground-state properties of a bosonic
Tonks-Girardeau gas confined in a one-dimensional periodic potential. The
single-particle reduced-density matrix is computed numerically for systems up
to N=41 bosons. Then we are able to study the scaling behavior of the
occupation numbers of the most dominant orbital for both commensurate and
non-commensurate cases, which correspond to an insulating phase and a
conducting phase, respectively. We find that, in the commensurate case, the
fractional occupation decays as $f_0 \propto 1/\ln N$ with the particle number,
while $f_0 \propto 1/N^{0.44}$ in the non-commensurate case. So there is no BEC
in both cases. The study of zero momentum peaks shows that $n(0)\propto N$ in
commensurate case, which implies that all bonons are localized in the
insulating phase.
\\ ( , 883kb)
Date: Sat, 6 Dec 2008 22:12:50 GMT (1190kb)

Title: Exploring Universality of Few-Body Physics Based on Ultracold Atoms Near
   Feshbach Resonances
Authors: Nathan Gemelke, Chen-Lung Hung, Xibo Zhang, Cheng Chin
Categories: cond-mat.other
Comments: ICAP 2008 Proceeding
   A universal characterization of interactions in few- and many-body quantum
systems is often possible without detailed description of the interaction
potential, and has become a defacto assumption for cold atom research.
Universality in this context is defined as the validity to fully characterize
the system in terms of two-body scattering length. We discuss universality in
the following three contexts: closed-channel dominated Feshbach resonance,
Efimov physics near Feshbach resonances, and corrections to the mean field
energy of Bose-Einstein condensates with large scattering lengths. Novel
experimental tools and strategies are discussed to study universality in
ultracold atomic gases: dynamic control of interactions, run-away evaporative
cooling in optical traps, and preparation of few-body systems in optical
\\ ( , 1190kb)
Date: Sun, 7 Dec 2008 09:35:57 GMT (318kb,D)

Title: Critical properties of a trapped interacting Bose gas
Authors: A. Bezett and P. B. Blakie
Categories: cond-mat.stat-mech
Comments: 10 pages, 9 figures
   We develop a practical theoretical formalism for studying the critical
properties of a trapped Bose-Einstein condensate using the projected
Gross-Pitaevskii equation. We show that this approach allows us investigate the
behavior of the correlation length, condensate mode and its number fluctuations
about the critical point. Motivated by recent experiments [Science {\bf 315},
1556 (2007)] we calculate the critical exponent for the correlation length,
observe clear finite-size effects, and develop characteristic length scales to
characterize the finite-size influences. We extend the Binder cumulant to the
trapped system and discuss an experimental method for measuring number
\\ ( , 318kb)
Date: Mon, 8 Dec 2008 09:34:36 GMT (510kb)

Title: Vortex splitting and phase separating instabilities of coreless vortices
   in F=1 spinor Bose-Einstein condensates
Authors: M. Takahashi, V. Pietila, M. Mottonen, T. Mizushima, K. Machida
Categories: cond-mat.other
Comments: 11 pages, 9 figures
   The low lying excitations of coreless vortex states in F = 1 spinor
Bose-Einstein condensates (BECs) are theoretically investigated using the
Gross-Pitaevskii and Bogoliubov-de Gennes equations. The spectra of the
elementary excitations are calculated for different spin-spin interaction
parameters and ratios of the number of particles in each sublevel. There exist
dynamical instabilities of the vortex state which are suppressed by
ferromagnetic interactions, and conversely, enhanced by antiferromagnetic
interactions. In both of the spin-spin interaction regimes, we find vortex
splitting instabilities in analogy with scalar BECs. In addition, a phase
separating instability is found in the antiferromagnetic regime.
\\ ( , 510kb)
Date: Sat, 6 Dec 2008 11:39:55 GMT (3199kb)

Title: Feshbach Resonances in Ultracold Gases
Authors: Cheng Chin, Rudolf Grimm, Paul Julienne, and Eite Tiesinga
Categories: cond-mat.other
Comments: Review article, 63 pages, 48 figures
   Feshbach resonances are the essential tool to control the interaction between
atoms in ultracold quantum gases. They have found numerous experimental
applications, opening up the way to important breakthroughs. This Review
broadly covers the phenomenon of Feshbach resonances in ultracold gases and
their main applications. This includes the theoretical background and models
for the description of Feshbach resonances, the experimental methods to find
and characterize the resonances, a discussion of the main properties of
resonances in various atomic species and mixed-species systems, and an overview
of key experiments with atomic Bose-Einstein condensates, degenerate Fermi
gases, and ultracold molecules.
\\ ( , 3199kb)
Date: Mon, 8 Dec 2008 17:08:48 GMT (103kb)

Title: Coherence properties and luminescence spectra of condensed polaritons in
   CdTe microcavities
Authors: M. H. Szymanska, F. M. Marchetti, J. Keeling, P. B. Littlewood
Categories: cond-mat.other
Comments: 7 pages, 6 figures
Journal-ref: Solid State Commun. 144, 364 (2007)
   We analyse the spatial and temporal coherence properties of a two-dimensional
and finite sized polariton condensate with parameters tailored to the recent
experiments which have shown spontaneous and thermal equilibrium polariton
condensation in a CdTe microcavity [J. Kasprzak, M. Richard, S. Kundermann, A.
Baas, P. Jeambrun, J.M.J. Keeling, F.M. Marchetti, M.H. Szymanska, R. Andre,
J.L. Staehli, et al., Nature 443 (7110) (2006) 409]. We obtain a theoretical
estimate of the thermal length, the lengthscale over which full coherence
effectively exists (and beyond which power-law decay of correlations in a
two-dimensional condensate occurs), of the order of 5 micrometers. In addition,
the exponential decay of temporal coherence predicted for a finite size system
is consistent with that found in the experiment. From our analysis of the
luminescence spectra of the polariton condensate, taking into account pumping
and decay, we obtain a dispersionless region at small momenta of the order of 4
degrees. In addition, we determine the polariton linewidth as a function of the
pump power. Finally, we discuss how, by increasing the exciton-photon detuning,
it is in principle possible to move the threshold for condensation from a
region of the phase diagram where polaritons can be described as a weakly
interacting Bose gas to a region where instead the composite nature of
polaritons becomes important.
\\ ( , 103kb)
Date: Mon, 8 Dec 2008 20:16:04 GMT (1635kb)

Title: Emergent Time Scale in Entangled Quantum Dynamics of Ultracold Molecules
   in Optical Lattices
Authors: M. L. Wall and L. D. Carr
Categories: cond-mat.other
Comments: 31 pages, 13 figures
   We derive a novel lattice Hamiltonian, the \emph{Molecular Hubbard
Hamiltonian} (MHH), which describes the essential many body physics of
closed-shell ultracold heteronuclear molecules in their absolute ground state
in a quasi-one-dimensional optical lattice. The MHH is explicitly
time-dependent, making a dynamic generalization of the concept of quantum phase
transitions necessary. Using the Time-Evolving Block Decimation (TEBD)
algorithm to study entangled dynamics, we demonstrate that, in the case of hard
core bosonic molecules at half filling, the MHH exhibits an emergent time scale
over which spatial entanglement grows, crystalline order appears, and
oscillations between rotational states self-damp into an asymptotic
superposition. We show that this time scale is a non-monotonic function of the
physical parameters describing the lattice. We also point out that experimental
mapping of the static phase boundaries of the MHH can be used to measure the
molecular polarizability tensor.
\\ ( , 1635kb)
Date: Sat, 6 Dec 2008 17:07:27 GMT (162kb)

Title: Entanglement control in coupled two-mode boson systems
Authors: A. V. Chizhov and R. G. Nazmitdinov
Categories: quant-ph
Comments: 4 pages, 2 figures
Journal-ref: Phys. Rev. A78, 064302 (2008)
DOI: 10.1103/PhysRevA.78.064302
   A two-mode boson model, widely used for the physics of fast rotating nuclei
and Bose-Einstein condensates, is studied in the context of entanglement
control. We derive an analytical expression for the entanglement between the
fields in this model as a function of time. We found that depending on the
interaction strengths between boson modes and the nature of the initial boson
states the dynamical evolution of the entanglement and the squeezing can occur
\\ ( , 162kb)
Date: Sun, 7 Dec 2008 20:06:33 GMT (419kb)

Title: Effective three-body interactions and decoherence of coherent atom
   states in optical lattices
Authors: P.R. Johnson, E. Tiesinga, J.V. Porto, C.J. Williams
Categories: quant-ph
Comments: 5 pages, 3 figures
   We show that virtual excitations of neutral bosons to higher vibrational
states in a three dimensional optical lattice generate effective attractive
three-body interactions. These processes can quickly decohere non-equilibrium
coherent states held in lattices, and this may explain the surprisingly rapid
damping of collapse and revival oscillations seen in some experiments. Longer
period, secondary revivals associated with the three-body interactions may also
be observable. Using Feshbach resonances it is possible to tune the effective
three-body interaction strength, creating new opportunities for studying the
effects of three-body interactions on the coherence and correlations of both
equilibrium and non-equilibrium many-body states.
\\ ( , 419kb)
Date: Fri, 5 Dec 2008 21:36:57 GMT (279kb)

Title: Ultracold molecules from ultracold atoms: a case study with the KRb
Authors: Paul S. Julienne
Categories: physics.atom-ph physics.chem-ph
Comments: Paper for the Discussions of the Faraday Society, Number 142: Cold
   and Ultracold Molecules, April 15-17, 2009, Durham University, UK
   Ultracold collisions of cold atoms or molecules make the bound states of the
collision complex formed from the two colliding species accessible for control
and manipulation of the cold species or the complex. Such resonances are best
treated by a resonant scattering theory, which in the ultracold domain can take
advantage of the properties of the long-range potential and the methods of
multichannel quantum defect theory. Coupled channels calculations on the
threshold scattering states and bound states of the 40K87Rb molecule illustrate
the ideas and methodology of quantum defect theory using the long-range
potential and also demonstrate the spin properties of the bound states
throughout the spectrum.
\\ ( , 279kb)
Date: Sun, 7 Dec 2008 20:07:49 GMT (1792kb)

Title: Two-color modulation transfer spectroscopy
Authors: A. Perez Galvan, D. Sheng, L. A. Orozco and Y. Zhao
Categories: physics.atom-ph
Comments: 14 pages, 13 figures, to be published in the Canadian Journal of
   We present two-color modulation transfer spectroscopy as a tool for precision
studies of atomic properties of excited states. The bi-colored technique
addresses a narrow set of velocity groups of a thermal atomic vapour using a
two-step transition to "burn a hole" in the velocity distribution. The
resulting spectrum presents sub-Doppler linewidths, good signal to noise ratio
and the trademark sidebands that work as an in situ ruler for the energy
spacing between atomic resonances. The spectra obtained can be used for
different applications such as measurements of energy splittings or
stabilization of laser frequencies to excited atomic transitions.
\\ ( , 1792kb)
Date: Mon, 8 Dec 2008 13:41:55 GMT (1301kb,D)

Title: A Stark decelerator on a chip
Authors: Samuel A Meek, Horst Conrad, Gerard Meijer
Categories: physics.atom-ph
Comments: 17 pages, 6 figures
   A microstructured array of 1254 electrodes on a substrate has been configured
to generate an array of local minima of electric field strength with a
periodicity of 120 $\mu$m about 25 $\mu$m above the substrate. By applying
sinusoidally varying potentials to the electrodes, these minima can be made to
move smoothly along the array. Polar molecules in low-field seeking quantum
states can be trapped in these traveling potential wells. Recently, we
experimentally demonstrated this by transporting metastable CO molecules at
constant velocities above the substrate [Phys. Rev. Lett. 100 (2008) 153003].
Here, we outline and experimentally demonstrate how this microstructured array
can be used to decelerate polar molecules directly from a molecular beam. For
this, the sinusoidally varying potentials need to be switched on when the
molecules arrive above the chip, their frequency needs to be chirped down in
time, and they need to be switched off before the molecules leave the chip
again. Deceleration of metastable CO molecules from an initial velocity of 360
m/s to a final velocity as low as 240 m/s is demonstrated in the 15-35 mK deep
potential wells above the 5 cm long array of electrodes. This corresponds to a
deceleration of almost $10^5$ $g$, and about 85 cm$^{-1}$ of kinetic energy is
removed from the metastable CO molecules in this process.
\\ ( , 1301kb)
Date: Mon, 8 Dec 2008 22:29:53 GMT (1998kb)

Title: Superconductivity close to the Mott state: From condensed-matter systems
   to superfluidity in optical lattices
Authors: Karyn Le Hur and T. Maurice Rice
Categories: cond-mat.supr-con cond-mat.str-el
Comments: 95 pages and 18 figures
   Since the discovery of high-temperature superconductivity in 1986 by Bednorz
and Mueller, great efforts have been devoted to finding out how and why it
works. From the d-wave symmetry of the order parameter, the importance of
antiferromagnetic fluctuations, and the presence of a mysterious pseudogap
phase close to the Mott state, one can conclude that high-Tc superconductors
are clearly distinguishable from the well-understood BCS superconductors. The
d-wave superconducting state can be understood through a Gutzwiller-type
projected BCS wave-function. In this review article, we revisit the Hubbard
model at half-filling and focus on the emergence of exotic superconductivity
with d-wave symmetry in the vicinity of the Mott state, starting from ladder
systems and then studying the dimensional crossovers to higher dimensions. This
allows to confirm that short-range antiferromagnetic fluctuations can mediate
superconductivity with d-wave symmetry. Ladders are also nice prototype systems
allowing to demonstrate the truncation of the Fermi surface and the emergence
of a Resonating Valence Bond (RVB) state with preformed pairs in the vicinity
of the Mott state. In two dimensions, a similar scenario emerges from
renormalization group arguments. We also discuss theoretical predictions for
the d-wave superconducting phase as well as the pseudogap phase, and address
the crossover to the overdoped regime. Finally, cold atomic systems with
tunable parameters also provide a complementary insight into this outstanding
\\ ( , 1998kb)
Date: Tue, 9 Dec 2008 13:13:32 GMT (168kb)

Title: Energy landscapes and their relation to thermodynamic phase transitions
Authors: Michael Kastner
Categories: cond-mat.stat-mech
Comments: 9 pages, 2 figures
   In order to better understand the occurrence of phase transitions, we adopt
an approach based on the study of energy landscapes: The relation between
stationary points of the potential energy landscape of a classical
many-particle system and the analyticity properties of its thermodynamic
functions is studied for finite as well as infinite systems. For finite
systems, each stationary point is found to cause a nonanalyticity in the
microcanonical entropy, and the functional form of this nonanalytic term can be
derived explicitly. With increasing system size, the order of the nonanalytic
term grows unboundedly, leading to an increasing differentiability of the
entropy. Therefore, in the thermodynamic limit, only asymptotically flat
stationary points may cause a phase transition to take place. For several spin
models, these results are illustrated by predicting the absence or presence of
a phase transition from stationary points and their local curvatures in
microscopic configuration space. These results establish a relationship between
properties of energy landscapes and the occurrence of phase transitions. Such
an approach appears particularly promising for the simultaneous study of
dynamical and thermodynamical properties, as is of interest for example for
protein folding or the glass transition.
\\ ( , 168kb)
Date: Tue, 9 Dec 2008 19:53:12 GMT (218kb)

Title: Relativistic BCS-BEC crossover of a two-species Fermi gas with number
   density asymmetry at zero temperature
Authors: Hao Guo, Chih-Chun Chien and Yan He
Categories: cond-mat.other
Comments: 10 pages, 6 figures
   We systematically study relativistic two-species fermions with tunable
attractive interactions and number-density asymmetry at zero temperature. In
general, a Bardeen-Cooper-Schrieffer (BCS) - Bose-Einstein Condensation (BEC) -
relativistic BEC (RBEC) crossover is observed. A BCS-type ground state and its
stability are analyzed using two equivalent formalisms. Phase separation in
real space is considered when homogeneous phases become unstable. In the
nonrelativistic limit, our results are consistent with well-known results. In
addition to a BCS-BEC crossover similar to that in the nonrelativistic case, in
the strongly attractive regime gapless excitations of antifermions and a RBEC
state are observed. We address how different phases respond to number density
asymmetry and present predictive phase diagrams of BCS-BEC-RBEC crossover.
\\ ( , 218kb)
Date: Mon, 8 Dec 2008 23:33:13 GMT (227kb)

Title: Interferometry with independent Bose-Einstein condensates: parity as an
   EPR/Bell quantum variable
Authors: Franck Lalo\"e (LKB - Lhomond), William Mullin (UMASS)
Categories: quant-ph cond-mat.other
   When independent Bose-Einstein condensates (BEC), described quantum
mechanically by Fock (number) states, are sent into interferometers, the
measurement of the output port at which the particles are detected provides a
binary measurement, with two possible results $\pm1$. With two interferometers
and two BEC's, the parity (product of all results obtained at each
interferometer) has all the features of an Einstein-Podolsky-Rosen quantity,
with perfect correlations predicted by quantum mechanics when the settings
(phase shifts of the interferometers) are the same. When they are different,
significant violations of Bell inequalities are obtained. These violations do
not tend to zero when the number $N$ of particles increases, and can therefore
be obtained with arbitrarily large systems, but a condition is that all
particles should be detected. We discuss the general experimental requirements
for observing such effects, the necessary detection of all particles in
correlation, the role of the pixels of the CCD detectors, and that of the
alignments of the interferometers in terms of matching of the wave fronts of
the sources in the detection regions. Another scheme involving three
interferometers and three BEC's is discussed; it leads to Greenberger Horne
Zeilinger (GHZ) sign contradictions, as in the usual GHZ case with three
particles, but for an arbitrarily large number of them. Finally,
generalizations of the Hardy impossibilities to an arbitrarily large number of
particles are introduced. BEC's provide a large versality for observing
violations of local realism in a variety of experimental arrangements.
\\ ( , 227kb)
Date: Tue, 9 Dec 2008 01:58:35 GMT (1336kb)

Title: Ultracold molecules: vehicles to scalable quantum information processing
Authors: Kathy-Anne Brickman Soderberg, Nathan Gemelke, Cheng Chin
Categories: quant-ph cond-mat.other
   We describe a novel scheme to implement scalable quantum information
processing using Li-Cs molecular state to entangle $^{6}$Li and $^{133}$Cs
ultracold atoms held in independent optical lattices. The $^{6}$Li atoms will
act as quantum bits to store information, and $^{133}$Cs atoms will serve as
messenger bits that aid in quantum gate operations and mediate entanglement
between distant qubit atoms. Each atomic species is held in a separate optical
lattice and the atoms can be overlapped by translating the lattices with
respect to each other. When the messenger and qubit atoms are overlapped,
targeted single spin operations and entangling operations can be performed by
coupling the atomic states to a molecular state with radio-frequency pulses. By
controlling the frequency and duration of the radio-frequency pulses,
entanglement can either be created or swapped between a qubit messenger pair.
We estimate operation fidelities for entangling two distant qubits and discuss
scalability of this scheme and constraints on the optical lattice lasers.
\\ ( , 1336kb)
Date: Tue, 9 Dec 2008 16:08:03 GMT (819kb)

Title: Jahn-Teller induced Berry phase in spin-orbit coupled Bose-Einstein
Authors: Jonas Larson and Erik Sjoqvist
Categories: quant-ph
Comments: 8 pages, 6 figures
   We demonstrate that Berry phases may greatly affect the dynamics of
spin-orbit coupled Bose-Einstein condensates. The effective model Hamiltonian
under consideration is shown to be equivalent to the Exe Jahn-Teller model
first introduced in molecular physics. The corresponding conical intersection
is identified and the Berry phase acquired for a wave packet encircling the
intersection studied. It is found that this phase manifests itself in the
density profile of the condensate, making it a directly measurable quantity via
time-of-flight detection. Moreover, the non-Abelian gauge structure of the
system is addressed and we verify how it affects the dynamics.
\\ ( , 819kb)
Date: Wed, 10 Dec 2008 03:42:36 GMT (119kb)

Title: Collective excitations and instabilities in multi-layer stacks of
   dipolar condensates
Authors: Daw-Wei Wang, and Eugene Demler
Categories: cond-mat.other cond-mat.supr-con
Comments: 5 pages with 3 figures
   We analyze theoretically the collective mode dispersion in multi-layer stacks
of two dimensional dipolar condensates and find a strong enhancement of the
roton instability. We discuss the interplay between the dynamical instability
and roton softening for moving condensates. We use our results to analyze the
decoherence rate of Bloch oscillations for systems in which the s-wave
scattering length is tuned close to zero using Feshbach resonance. Our results
are in qualitative agreement with recent experiments of Fattori {\it et al.} on
$^{39}$K atoms.
\\ ( , 119kb)
Date: Wed, 10 Dec 2008 14:50:35 GMT (388kb)

Title: The Stochastic Gross-Pitaevskii Equation and some Applications
Authors: S. P. Cockburn, N. P. Proukakis
Categories: cond-mat.other
Comments: 14 pages, 9 figures. To appear in the Laser Physics Special Issue on
   Physics of Cold Trapped Atoms
   The stochastic Gross-Pitaevskii equation represents a versatile approach for
studying the dynamics of trapped degenerate ultracold Bose gases in the
presence of large phase and density fluctuations. Following a brief review of
the original formulation of Stoof, which highlights the benefits of this
approach and its relation to alternative theories, we present selected
applications for the dynamics of effectively one-dimensional systems, and
briefly discuss the generalization to two-dimensional systems, highlighting
certain potential pitfalls in their numerical implementations.
\\ ( , 388kb)
Date: Wed, 10 Dec 2008 14:53:16 GMT (486kb,D)

Title: Quantum quenches from integrability: the fermionic pairing model
Authors: Alexandre Faribault, Pasquale Calabrese, Jean-Sebastien Caux
Categories: cond-mat.str-el cond-mat.mes-hall
Comments: 10 pages, 7 figures
   Understanding the non-equilibrium dynamics of extended quantum systems after
the trigger of a sudden, global perturbation (quench) represents a daunting
challenge, especially in the presence of interactions. The main difficulties
stem from both the vanishing time scale of the quench event, which can thus
create arbitrarily high energy modes, and its non-local nature, which curtails
the utility of local excitation bases. We here show that nonperturbative
methods based on integrability can prove sufficiently powerful to completely
characterize quantum quenches: we illustrate this using a model of fermions
with pairing interactions (Richardson's model). The effects of simple (and
multiple) quenches on the dynamics of various important observables are
discussed. Many of the features we find are expected to be universal to all
kinds of quench situations in atomic physics and condensed matter.
\\ ( , 486kb)
Date: Wed, 10 Dec 2008 17:30:00 GMT (597kb)

Title: Kinetic quantum phase transition in bosonic superfluids on a lattice
Authors: A. S. Alexandrov and I. O. Thomas
Categories: cond-mat.other
Comments: 4 pages, 3 figures. Submitted to Physical Review Letters
   It has long been known that quantum fluctuations induce a macroscopic phase
transition from a superfluid to a Mott insulator phase driven by the repulsive
potential energy in the ground state of bosons on a lattice as observed in
ultracold atomic gases on optical lattices (M. Grenier {\em et al.}, Nature,
{\bf 415,} 39 (2002)). Identifying the superfluid phase is often hard due to
the lack of clear criteria (R. B. Diener {\em et al.}, Phys. Rev. Lett. {\bf
98}, 180404 (2007); Y. Kato {\em et al.} Nature Phys. {\bf 4}, 617 (2008)). We
find a quantum phase transition from a homogeneous to a striped or checkerboard
Bose-condensate driven purely by the kinetic energy which provides a clear
identification of the superfluid state, and which may perhaps be reproduced
experimentally in optical lattices by the appropriate tuning of the lattice
\\ ( , 597kb)
Date: Wed, 10 Dec 2008 18:00:10 GMT (69kb)

Title: Quantum phase transition in Bose-Holstein model in two dimensions
Authors: Sanjoy Datta and Sudhakar Yarlagadda
Categories: cond-mat.str-el cond-mat.supr-con
   We derive an effective d-dimensional Hamiltonian for a system of
hard-core-bosons coupled to optical phonons in a lattice. Away from
half-filling, we show that the presence of next-nearest-neighbor hopping in the
effective Hamiltonian leads to a superfluid-to-supersolid transition at
intermediate boson-phonon (b-p) couplings, while at strong-couplings the system
phase separates. However, at half-filling and at a critical b-p coupling (as in
the xxz-model), the system undergoes a superfluid-to-charge-density-wave
transition without any signature of supersolidity. Our analyses is based on
extensive calculations of the structure factor, the superfluid fraction, the
Bose-Einstein condensate fraction, and the system energy at various fillings.
We present a phase diagram for this system and compare it to that of the
xxz-model. We also demonstrate explicitly that the next-nearest-neighbor
hopping (in the absence of nearest-neighbor hopping) in the effective
Hamiltonian leads only to a single transition, i.e., a first-order
superfluid-to-supersolid transition.
\\ ( , 69kb)
Date: Wed, 10 Dec 2008 18:44:32 GMT (117kb)

Title: Exploring dynamic localization with a Bose-Einstein condensate
Authors: Andre Eckardt, Martin Holthaus, Hans Lignier, Alessandro Zenesini,
   Donatella Ciampini, Oliver Morsch, and Ennio Arimondo
Categories: cond-mat.other
Comments: 7 pages, 5 figures accepted for publication in Phys. Rev. A
   We report on the experimental observation of dynamic localization of a
Bose-Einstein condensate in a shaken optical lattice, both for sinusoidal and
square-wave forcing. The formulation of this effect in terms of a quasienergy
band collapse, backed by the excellent agreement of the observed collapse
points with the theoretical predictions, suggests the feasibility of systematic
quasienergy band engineering.
\\ ( , 117kb)
Date: Wed, 10 Dec 2008 13:47:09 GMT (370kb)

Title: Dynamics of thermal Casimir-Polder forces on polar molecules
Authors: S.A. Ellingsen, S.Y. Buhmann, S. Scheel
Categories: quant-ph
Comments: 5 pages, 3 figures
   We study the influence of thermal Casimir-Polder forces on the near-surface
trapping of cold polar molecules, with emphasis on LiH and YbF near an Au
surface at room temperature. We show that for a molecule initially prepared in
its electronic and rovibrational ground state, the Casimir-Polder force
oscillates with the molecule-wall separation. The non-resonant force
contribution and the evanescent part of the resonant force contribution almost
exactly cancel at high temperature which results in a saturation of the
(attractive) force in this limit. A dynamical calculation reveals how the
spatial oscillations die out as thermalisation of the molecule with its
environment sets in.
\\ ( , 370kb)
Date: Wed, 10 Dec 2008 15:59:24 GMT (32kb)

Title: Zero-mode analysis of quantum statistical physics
Authors: A. Bessa, C.A.A. de Carvalho, E.S. Fraga
Categories: quant-ph
Comments: 9 pages, 5 figures
   We present a unified formulation for quantum statistical physics based on the
representation of the density matrix as a functional integral. We identify the
stochastic variable of the effective statistical theory that we derive as a
boundary configuration and a zero mode relevant to the discussion of infrared
physics. We illustrate our formulation by computing the partition function of
an interacting one-dimensional quantum mechanical system at finite temperature
from the path-integral representation for the density matrix. The method of
calculation provides an alternative to the usual sum over periodic
trajectories: it sums over paths with coincident endpoints, and includes
non-vanishing boundary terms. An appropriately modified expansion into
Matsubara modes provides a natural separation of the zero-mode physics. This
feature may be useful in the treatment of infrared divergences that plague the
perturbative approach in thermal field theory.
\\ ( , 32kb)
Date: Thu, 11 Dec 2008 20:36:33 GMT (2753kb)

Title: Supersolid state in fermionic optical lattice systems
Authors: Akihisa Koga, Takuji Higashiyama, Kensuke Inaba, Seiichiro Suga, and
   Norio Kawakami
Categories: cond-mat.supr-con
Comments: 7 pages, 5 figures, Phys. Rev. A in press
   We study ultracold fermionic atoms trapped in an optical lattice with
harmonic confinement by combining the real-space dynamical mean-field theory
with a two-site impurity solver. By calculating the local particle density and
the pair potential in the systems with different clusters, we discuss the
stability of a supersolid state, where an s-wave superfluid coexists with a
density-wave state of checkerboard pattern. It is clarified that a confining
potential plays an essential role in stabilizing the supersolid state. The
phase diagrams are obtained for several effective particle densities.
\\ ( , 2753kb)
Date: Thu, 11 Dec 2008 18:27:56 GMT (370kb)

Title: Intense Atomic and Molecular Beams via Neon Buffer Gas Cooling
Authors: David Patterson, Julia Rasmussen and John M. Doyle
Categories: physics.atom-ph
Comments: 15 pages, 6 figures
   We realize a continuous guided beam of cold deuterated ammonia with a flux of
3e11 ND3 molecules/s and a continuous free-space beam of cold potassium with a
flux of 1e16 K atoms/s. A novel feature of the buffer gas source used to
produce these beams is cold neon, which, due to intermediate Knudsen number
beam dynamics, produces a forward velocity and low-energy tail that is
comparable to much colder helium-based sources. We expect this source to be
trivially generalizable to a very wide range of atomic and molecular species
with significant vapor pressure below 1000 K. This source has properties that
make it a good starting point for laser cooling of molecules or atoms, cold
collision studies, trapping, or nonlinear optics in buffer-gas-cooled atomic or
molecular gases.
\\ ( , 370kb)
Date: Thu, 11 Dec 2008 06:32:05 GMT (1195kb)

Title: A dynamic scheme for generating number squeezing in Bose-Einstein
   condensates through nonlinear interactions
Authors: S. A. Haine and M. T. Johnsson
Categories: quant-ph
Comments: 4 pages, 3 figures
   We develop a scheme to generate number squeezing in a Bose-Einstein
condensate by utilizing interference between two hyperfine levels and nonlinear
atomic interactions. We describe the scheme using a multimode quantum field
model and find agreement with a simple analytic model in certain regimes. We
demonstrate that the scheme gives strong squeezing for realistic choices of
parameters and atomic species. The number squeezing can result in noise well
below the quantum limit, even if the initial noise on the system is classical
and much greater than that of a poisson distribution.
\\ ( , 1195kb)
arXiv:0812.1924 (*cross-listing*)
Date: Wed, 10 Dec 2008 14:18:09 GMT (611kb,D)

Title: Stabilization of two-dimensional solitons and vortices against
   supercritical collapse by lattice potentials
Authors: Rodislav Driben and Boris A. Malomed
Categories: nlin.PS physics.optics
Comments: European Physical Journal D, in press
   It is known that optical-lattice (OL) potentials can stabilize solitons and
solitary vortices against the critical collapse, generated by the cubic
attractive nonlinearity in the 2D geometry. We demonstrate OLs can also
stabilize various species of fundamental and vortical solitons against the
super-critical collapse, driven by the double-attractive cubic-quintic
nonlinearity (however, solitons remain unstable in the case of the pure quintic
nonlinearity). Two types of OLs are considered, producing similar results: the
2D Kronig-Penney "checkerboard", and the sinusoidal potential. Soliton families
are obtained by means of a variational approximation, and as numerical
solutions. The stability of the families, which include fundamental and
multi-humped solitons, vortices of oblique and straight types, vortices built
of quadrupoles, and supervortices, strictly obeys the Vakhitov-Kolokolov
criterion. The model applies to optical media and BEC in "pancake" traps.
\\ ( , 611kb)

The replacements:

replaced with revised version Thu, 4 Dec 2008 22:10:08 GMT (698kb)

Title: Third quantization: a general method to solve master equations for
   quadratic open Fermi systems
Authors: Tomaz Prosen
Categories: quant-ph cond-mat.stat-mech nlin.SI
Comments: 24 pages, with 8 eps figures - few minor corrections to the published
   version, e.g. anti-symmetrizing the matrix given by eq. (27)
Journal-ref: New J. Phys. 10, 043026 (2008)
\\ ( , 698kb)
replaced with revised version Fri, 5 Dec 2008 20:50:49 GMT (7kb)

Title: Observation of the Nuclear Magnetic Octupole Moment of 87Rb from
   Spectroscopic Measurements of Hyperfine Intervals
Authors: Vladislav Gerginov, Carol E. Tanner and W. R. Johnson
Categories: physics.atom-ph
\\ ( , 7kb)
replaced with revised version Fri, 5 Dec 2008 13:12:42 GMT (58kb)

Title: Measurement of the quadratic Zeeman shift of ^{85}Rb hyperfine sublevels
   using stimulated Raman transitions
Authors: Runbing Li, Lin Zhou, Jin Wang, Mingsheng Zhan
Categories: physics.atom-ph
\\ ( , 58kb)
replaced with revised version Mon, 8 Dec 2008 20:42:38 GMT (42kb)

Title: A Unitary Fermi Supersolid: The Larkin-Ovchinnikov Phase
Authors: Aurel Bulgac and Michael McNeil Forbes
Categories: cond-mat.supr-con hep-ph nucl-th
Comments: 4 pages, 3 figures, RevTeX4. (Minor updates to correspond with
   published version.)
Report-no: NG-0809
Journal-ref: Phys. Rev. Lett. 101 (2008) 215301
DOI: 10.1103/PhysRevLett.101.215301
\\ ( , 42kb)
replaced with revised version Mon, 8 Dec 2008 17:23:45 GMT (222kb)

Title: Probing Fermionic Condensates by Fast-Sweep Projection onto Feshbach
Authors: S. Matyjaskiewicz, M. H. Szymanska, K. Goral
Categories: cond-mat.other
Comments: 4 pages, 3 figures, revised version
Journal-ref: Phys. Rev. Lett. 101, 150410 (2008)
DOI: 10.1103/PhysRevLett.101.150410
\\ ( , 222kb)
replaced with revised version Mon, 8 Dec 2008 01:41:25 GMT (204kb)

Title: Spin echo in spinor dipolar Bose-Einstein condensates
Authors: Masashi Yasunaga and Makoto Tsubota
Categories: cond-mat.other
Comments: 4 pages, 5 figures
Journal-ref: Phys. Rev. Lett. 101, 220401 (2008)
\\ ( , 204kb)
replaced with revised version Mon, 8 Dec 2008 04:40:14 GMT (53kb)

Title: Phases and collective modes of hardcore Bose-Fermi mixture in an optical
Authors: S. Sinha and K. Sengupta
Categories: cond-mat.str-el
Comments: 10 pages 6 Figs v2: Updated version with more refs and additional
\\ ( , 53kb)
replaced with revised version Fri, 5 Dec 2008 21:32:46 GMT (22kb)

Title: Hypothesis testing for Gaussian states on bosonic lattices
Authors: Milan Mosonyi
Categories: quant-ph math-ph math.MP
Comments: 22 pages, submitted version
\\ ( , 22kb)
replaced with revised version Mon, 8 Dec 2008 20:51:40 GMT (311kb)

Title: Gaussian wave packets in phase space: The Fermi g_F function
Authors: Giuliano Benenti, Giuliano Strini
Categories: quant-ph
Comments: 7 pages, 4 figures, remarks added
\\ ( , 311kb)
replaced with revised version Tue, 9 Dec 2008 11:14:48 GMT (2450kb,D)

Title: Squeezing and entanglement in a Bose-Einstein condensate
Authors: J. Esteve, C. Gross, A. Weller, S. Giovanazzi, M.K. Oberthaler
   (Kirchhoff Institut f\"ur Physik, Heidelberg, Germany)
Categories: cond-mat.other quant-ph
DOI: 10.1038/nature07332
\\ ( , 2450kb)
replaced with revised version Tue, 9 Dec 2008 14:47:13 GMT (60kb)

Title: Feshbach-Einstein condensates
Authors: Valy G. Rousseau, Peter J.H. Denteneer
Categories: cond-mat.stat-mech
Comments: 4 pages, 6 figures
\\ ( , 60kb)
replaced with revised version Tue, 9 Dec 2008 12:48:15 GMT (265kb)

Title: Bifurcations, order, and chaos in the Bose-Einstein condensation of
   dipolar gases
Authors: Patrick K\"oberle, Holger Cartarius, Toma\v{z} Fab\v{c}i\v{c}, J\"org
   Main, G\"unter Wunner
Categories: quant-ph nlin.CD
Comments: 10 pages, 4 figures, minor changes in the text and additional
   reference added
\\ ( , 265kb)
arXiv:0812.1709 (*cross-listing*)
Date: Tue, 9 Dec 2008 14:58:23 GMT (41kb)

Title: Many Body Theory for Quartets, Trions, and Pairs in Low Density
   Multi-Component Fermi-Systems
Authors: P. Schuck, T. Sogo, and G. R\"opke
Categories: nucl-th cond-mat.other
   A selfconsistent many body approach for the description of gases with
quartets, trions, and pairs is presented. Applications to 3D Fermi systems at
low density are discussed.
\\ ( , 41kb)
replaced with revised version Wed, 10 Dec 2008 09:16:57 GMT (74kb)

Title: Number of closed-channel molecules in the BEC-BCS crossover
Authors: Felix Werner (LKB - Lhomond), Leticia Tarruell (LKB - Lhomond), Yvan
   Castin (LKB - Lhomond)
Categories: cond-mat.other
\\ ( , 74kb)
replaced with revised version Wed, 10 Dec 2008 17:54:13 GMT (15kb)

Title: Tunneling-induced damping of phase coherence revivals in deep optical
Authors: Uwe R. Fischer and Ralf Sch\"utzhold
Categories: cond-mat.other quant-ph
Comments: 4+epsilon pages of RevTex4; Rapid Communication in Physical Review A
Journal-ref: Phys. Rev. A 78, 061603(R) (2008)
DOI: 10.1103/PhysRevA.78.061603
\\ ( , 15kb)
replaced with revised version Wed, 10 Dec 2008 04:23:07 GMT (614kb)

Title: Probing condensate order in deep optical lattices
Authors: Kuei Sun, Courtney Lannert, Smitha Vishveshwara
Categories: cond-mat.other
Comments: 14 pages, 9 figures, RevTeX; content changed, references added
\\ ( , 614kb)
replaced with revised version Wed, 10 Dec 2008 09:57:10 GMT (54kb)

Title: Establishing EPR-channels between Nanomechanics and Atomic Ensembles
Authors: K. Hammerer, M. Aspelmeyer, E.S. Polzik, P. Zoller
Categories: quant-ph
Comments: 4 pages, 1 figure; accepted by PRL
\\ ( , 54kb)
replaced with revised version Wed, 10 Dec 2008 01:20:39 GMT (735kb)

Title: Nuclear quadrupole resonances in compact vapor cells: the crossover from
   the NMR to the NQR interaction regimes
Authors: E.A. Donley, J.L. Long, T.C. Liebisch, E.R. Hodby, T.A. Fisher, and J.
Categories: quant-ph
Comments: 4 pages, 4 figures
\\ ( , 735kb)
replaced with revised version Thu, 11 Dec 2008 19:24:33 GMT (39kb)

Title: Odd-frequency pairing in a binary mixture of bosonic and fermionic cold
Authors: Ryan M. Kalas, Alexander V. Balatsky, Dmitry Mozyrsky
Categories: cond-mat.other
Comments: Final version
Journal-ref: Phys. Rev. B 78, 184513 (2008)
DOI: 10.1103/PhysRevB.78.184513
\\ ( , 39kb)
replaced with revised version Thu, 11 Dec 2008 08:49:00 GMT (46kb)

Title: Superfluidity near phase separation in Bose-Fermi mixtures
Authors: Tilman Enss, Wilhelm Zwerger
Categories: cond-mat.other cond-mat.supr-con
Comments: 7 pages and 3 figures, accepted version
\\ ( , 46kb)
replaced with revised version Thu, 11 Dec 2008 16:11:49 GMT (182kb)

Title: Probing spatial spin correlations of ultracold gases by quantum noise
Authors: G. M. Bruun, Brian M. Andersen, Eugene Demler and Anders S.
Categories: cond-mat.other
Comments: Revised version. 4 pages, 3 figures. Accepted for PRL
\\ ( , 182kb)
replaced with revised version Thu, 11 Dec 2008 11:31:50 GMT (380kb)

Title: Quantum phases of a Two-Dimensional Dipolar Fermi Gas
Authors: G. M. Bruun and E. Taylor
Categories: cond-mat.other
Comments: 4 pages, 4 figures
Journal-ref: Phys. Rev. Lett. 101, 245301 (2008)
DOI: 10.1103/PhysRevLett.101.245301
\\ ( , 380kb)
replaced with revised version Tue, 9 Dec 2008 15:50:17 GMT (865kb,D)

Title: Dimer-dimer collisions at finite energies in two-component Fermi gases
Authors: J. P. D'Incao, Seth T. Rittenhouse, N. P. Mehta, Chris H. Greene
Categories: physics.atom-ph
Comments: 4.1 pages, 3 figures, revised text
\\ ( , 865kb)

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,        
Matt's arXiv selection: weekly summary of cold-atom papers from
Legal stuff: Unless stated otherwise, this e-mail represents only the
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