From: Matthew Davis <mdavis_at_physics.uq.edu.au>

Date: Fri, 23 Nov 2007 14:46:30 +1000

Date: Fri, 23 Nov 2007 14:46:30 +1000

The following message was sent to the matts_arxiv list by Matthew Davis <mdavis_at_physics.uq.edu.au>

At least I haven't fallen further behind this week... 34 new preprints and 9

replacements:

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arXiv:0710.5060

Date: Fri, 26 Oct 2007 11:21:05 GMT (896kb)

Title: Kosterlitz-Thouless transition of the quasi two-dimensional trapped Bose

gas

Authors: Markus Holzmann and Werner Krauth

Categories: cond-mat.stat-mech

Comments: 4 pages, 4 figures

\\

We present Quantum Monte Carlo calculations with up to N=576000 interacting

bosons in a quasi two-dimensional trap geometry closely related to recent

experiments with atomic gases. The density profile of the gas and the

non-classical moment of inertia yield intrinsic signatures for the

Kosterlitz--Thouless transition temperature T_KT. From the reduced one-body

density matrix, we compute the condensate fraction, which is quite large for

small systems. It decreases slowly with increasing system sizes, vanishing in

the thermodynamic limit. We interpret our data in the framework of the

local-density approximation, and point out the relevance of our results for the

analysis of experiments.

\\ ( http://arxiv.org/abs/0710.5060 , 896kb)

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arXiv:0710.5083

Date: Fri, 26 Oct 2007 13:06:53 GMT (254kb)

Title: Control of Interaction-Induced Dephasing of Bloch Oscillations

Authors: M. Gustavsson, E. Haller, M.J. Mark, J.G. Danzl, G. Rojas-Kopeinig,

H.-C. Naegerl

Categories: cond-mat.other

Comments: 4 pages, 5 figures

\\

We report on the control of interaction-induced dephasing of Bloch

oscillations for an atomic Bose-Einstein condensate in an optical lattice under

the influence of gravity. When tuning the strength of the interaction towards

zero by means of a Feshbach resonance, the dephasing time is increased from a

few to more than twenty thousand Bloch oscillation periods. We quantify the

dephasing in terms of the width of the quasi-momentum distribution and measure

its dependence on time for different values of the scattering length.

Minimizing the dephasing allows us to realize a BEC-based atom interferometer

in the non-interacting limit. We use it for a precise determination of a

zero-crossing for the atomic scattering length and to observe collapse and

revivals of Bloch oscillations when the atomic sample is subject to a spatial

force gradient.

\\ ( http://arxiv.org/abs/0710.5083 , 254kb)

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arXiv:0710.5099

Date: Fri, 26 Oct 2007 14:28:30 GMT (405kb)

Title: Creation of robust entangled states and new resources for

measurement-based quantum computation using optical superlattices

Authors: B. Vaucher, A. Nunnenkamp, and D. Jaksch

Categories: cond-mat.other

Comments: 23 pages, 6 figures, IOP style

\\

We investigate how to create robust entangled states of ultracold atoms

trapped in optical lattices by dynamically manipulating the shape of the

lattice potential. We consider an additional potential (the superlattice) that

allows both the splitting of each site into a double well potential, and the

control of the height of potential barrier between sites. We use superlattice

manipulations to perform entangling operations between neighbouring qubits

encoded on the Zeeman levels of the atoms without having to perform transfers

between the different vibrational states of the atoms. We show how to use

superlattices to engineer robust many-body entangled states. Also, we present a

method to realize a 2D resource for measurement-based quantum computing via

Bell-pair measurements that is resilient to collective dephasing noise. We

analyze measurement networks that allow the execution of quantum algorithms

while maintaining the resilience properties of the system throughout the

computation.

\\ ( http://arxiv.org/abs/0710.5099 , 405kb)

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arXiv:0710.5131

Date: Fri, 26 Oct 2007 16:05:43 GMT (241kb)

Title: Atom interferometry with a weakly-interacting Bose Einstein condensate

Authors: Marco Fattori, Chiara D'Errico, Giacomo Roati, Matteo Zaccanti, Mattia

Jona-Lasinio, Michele Modugno, Massimo Inguscio and Giovanni Modugno

Categories: cond-mat.other

Comments: 5 pages, 5 figures

\\

We demonstrate the operation of an atom interferometer based on a weakly

interacting Bose-Einstein condensate. We strongly reduce the interaction

induced decoherence that usually limits interferometers based on trapped

condensates by tuning the s-wave scattering length almost to zero via a

magnetic Feshbach resonance. We employ a $^{39}$K condensate trapped in an

optical lattice, where Bloch oscillations are forced by gravity. With a control

of the scattering length better that 0.1 $a_0$ we achieve coherence times of

several hundreds of ms. The micrometric sizes of the atomic sample make our

sensor an ideal candidate for measuring forces with high spatial resolution.

Our technique can be in principle extended to other measurement schemes opening

new possibilities in the field of trapped atom interferometry.

\\ ( http://arxiv.org/abs/0710.5131 , 241kb)

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arXiv:0709.2747

Date: Tue, 18 Sep 2007 02:35:47 GMT (312kb)

Title: Spin squeezing and maximal-squeezing time

Authors: Guang-Ri Jin and Sang Wook Kim

Categories: quant-ph cond-mat.other

Comments: 7 pages, 5 figures, 1 table. Resubmitted to Phys. Rev. A

Journal-ref: Phys. Rev. A76, 043621(2007)

DOI: 10.1103/PhysRevA.76.043621

\\

Spin squeezing of a nonlinear interaction model with Josephson-like coupling

is studied to obtain time scale of maximal squeezing. Based upon two exactly

solvable cases for two and three particles, we find that the maximal-squeezing

time depends on the level spacing between the ground state and its next

neighbor eigenstate.

\\ ( http://arxiv.org/abs/0709.2747 , 312kb)

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arXiv:0710.0110

Date: Sun, 30 Sep 2007 06:48:05 GMT (122kb)

Title: Storage of spin squeezing in a two-component Bose-Einstein condensate

Authors: Guang-Ri Jin and Sang Wook Kim

Categories: quant-ph cond-mat.other

Comments: 10 pages, 5 figures. This version is slightly different from the one

published in Phys. Rev. Lett

Journal-ref: Phys. Rev. Lett.99, 170405 (2007)

DOI: 10.1103/PhysRevLett.99.170405

\\

Efficient control of spin squeezing in a two-component Bose-Einstein

Condensate is studied by rapidly turning-off the external field at a time that

maximal spin squeezing appears. We show that strong reduction of spin

fluctuation can be maintained in a nearly fixed direction for a long time. We

explain the underlying physics unambiguously, and present analytical

expressions of the maximal-squeezing time.

\\ ( http://arxiv.org/abs/0710.0110 , 122kb)

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arXiv:0710.4402

Date: Wed, 24 Oct 2007 08:16:00 GMT (171kb)

Title: Control of Optical Dynamic Memory Capacity of an Atomic Bose-Einstein

Condensate

Authors: Devrim Tarhan, Alphan Sennaroglu, Ozgur E. Mustecaplioglu

Categories: quant-ph cond-mat.other

Comments: 4 figures, 9 pages

\\

Light storage in an atomic Bose-Einstein condensate is one of the most

practical usage of these coherent atom-optical systems. In order to make them

even more practical, it is necessary to enhance our ability to inject multiple

pulses into the condensate. In this paper, we report that dispersion of pulses

injected into the condensate can be compensated by optical nonlinearity. In

addition, we will present a brief review of our earlier results in which

enhancement of light storage capacity is accomplished by utilizing multi-mode

light propagation or choosing an optimal set of experimental parameters.

\\ ( http://arxiv.org/abs/0710.4402 , 171kb)

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arXiv:0710.4860

Date: Thu, 25 Oct 2007 13:21:46 GMT (236kb)

Title: Loschmidt cooling by time reversal of atomic matter waves

Authors: J. Martin, B. Georgeot, D. L. Shepelyansky (CNRS, Toulouse)

Categories: cond-mat.stat-mech nlin.CD quant-ph

Comments: revtex 4 pages, 5 figs, research at http://www.quantware.ups-tlse.fr/

\\

We propose an experimental scheme which allows to realize approximate time

reversal of matter waves of ultracold atoms in the regime of quantum chaos. We

show that a significant fraction of the atoms return back to their original

state, being at the same time cooled down by two orders of magnitude. We give a

theoretical description of this effect supported by extensive numerical

simulations. The proposed scheme can be implemented with existing experimental

setups.

\\ ( http://arxiv.org/abs/0710.4860 , 236kb)

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arXiv:0710.5187

Date: Fri, 26 Oct 2007 22:14:19 GMT (445kb)

Title: Phase Coherence and Superfluid-Insulator Transition in a Disordered

Bose-Einstein Condensate

Authors: Yong P. Chen, J. Hitchcock, D. Dries, M. Junker, C. Welford, R. G.

Hulet

Categories: cond-mat.other

Comments: 5 pages, 4 figures

\\

We have studied the effects of a disordered optical potential on the

transport and phase coherence of a Bose-Einstein condensate (BEC) of 7Li atoms.

At moderate disorder strengths (V_D), we observe inhibited transport and

damping of dipole excitations, while in time-of-flight images, random but

reproducible interference patterns are observed. The interference reflects

phase coherence in the disordered BEC and is interpreted as speckle for matter

waves. At higher V_D, the interference contrast diminishes as the BEC fragments

into multiple pieces with little phase coherence.

\\ ( http://arxiv.org/abs/0710.5187 , 445kb)

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arXiv:0710.5210

Date: Sat, 27 Oct 2007 07:10:53 GMT (10kb)

Title: Dynamical symmetry in spinor Bose-Einstein condensates

Authors: Shun Uchino, Takaharu Otsuka, Masahito Ueda

Categories: cond-mat.other

Comments: 18 pages

\\

We demonstrate that dynamical symmetry plays a crucial role in determining

the structure of the eigenspectra of spinor Bose-Einstein condensates (BECs).

In particular, the eigenspectra of spin-1 and spin-2 BECs in the single-mode

approximation are shown to be completely determined by dynamical symmetries,

where a spin-2 BEC corresponds to the U(5) limit of the interacting boson model

in nuclear physics. The eigenspectrum of a spin-3 BEC is solved exactly for a

specific class of coupling constants, while it is shown that dynamical symmetry

alone is not enough to determine the spectrum for arbitrary coupling constants.

\\ ( http://arxiv.org/abs/0710.5210 , 10kb)

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arXiv:0710.5223

Date: Sat, 27 Oct 2007 12:18:05 GMT (132kb)

Title: Phase space deformation of a trapped dipolar Fermi gas

Authors: Takahiko Miyakawa, Takaaki Sogo, Han Pu

Categories: cond-mat.other

Comments: 5 pages, 5 figures

\\

We consider a system of quantum degenerate spin polarized fermions in a

harmonic trap at zero temperature, interacting via dipole-dipole forces. We

introduce a variational Wigner function to describe the deformation and

compression of the Fermi gas in phase space and use it to examine the stability

of the system. We emphasize the important roles played by the Fock exchange

term of the dipolar interaction which results in a non-spherical Fermi surface.

\\ ( http://arxiv.org/abs/0710.5223 , 132kb)

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arXiv:0710.5288

Date: Sun, 28 Oct 2007 14:53:54 GMT (36kb)

Title: BCS-BEC crossover in a strongly correlated Fermi gas

Authors: S. G. Bhongale, M. R. Goosen, and S.J.J.M.F. Kokkelmans

Categories: cond-mat.mes-hall

Comments: 4 pages, 3 figures

\\

We study the BCS-BEC crossover in the strongly correlated regime of an

ultra-cold rotating two component Fermi gas. Strong correlations are shown to

generate an additional long-range interaction which results in a modified

crossover region compared to the non-rotating situation. The two-particle

correlation function reveals a smooth crossover between the s-wave paired

fermionic fractional quantum Hall state and the bosonic Laughlin state.

\\ ( http://arxiv.org/abs/0710.5288 , 36kb)

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arXiv:0710.5318

Date: Sun, 28 Oct 2007 23:01:48 GMT (16kb)

Title: Phase diagram of a Bose gas near a wide Feshbach resonance

Authors: Lan Yin

Categories: cond-mat.other cond-mat.stat-mech cond-mat.str-el cond-mat.supr-con

Comments: 4 pages, 4 figures

\\

In this paper, we study the phase diagram of a homogeneous Bose gas with a

repulsive interaction near a wide Feshbach resonance at zero temperature. The

Bose-Einstein-condensation (BEC) state of atoms is a metastable state. When the

scattering length $a$ exceeds a critical value depending on the atom density

$n$, $na^3>0.035$, the molecular excitation energy is imaginary and the atomic

BEC state is dynamically unstable against molecule formation. The BEC state of

diatomic molecules has lower energy, where the atomic excitation is gapped and

the molecular excitation is gapless. However when the scattering length is

above another critical value, $na^3>0.0164$, the molecular BEC state becomes a

unstable coherent mixture of atoms and molecules.

\\ ( http://arxiv.org/abs/0710.5318 , 16kb)

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arXiv:0710.5481

Date: Mon, 29 Oct 2007 16:59:57 GMT (629kb)

Title: Bose-Einstein condensates of atoms with arbitrary spin

Authors: P. Van Isacker (GANIL), S. Heinze

Categories: cond-mat.other

Comments: Journal of Physics A, in press

Proxy: ccsd in2p3-00183262

Report-no: GANIL P 07 20

\\

We show that the ground state of a Bose-Einstein condensate of atoms with

hyperfine spin f = 2 can be either spin aligned, condensed into pairs of atoms

coupled to F = 0, or condensed into triplets of atoms coupled to F = 0. The

complete phase diagram is constructed for f = 2 and the generic properties of

the phase diagram are obtained for f > 2.

\\ ( http://arxiv.org/abs/0710.5481 , 629kb)

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arXiv:0710.5484

Date: Mon, 29 Oct 2007 16:09:03 GMT (1484kb)

Title: Exploring Exotic Superfluidity of Polarized Ultracold Fermions in

Optical Lattices

Authors: Y. Chen, Z. D. Wang, F. C. Zhang, and C. S. Ting

Categories: cond-mat.supr-con

Comments: 5 pages, 4 figures

\\

We explore theoretically the novel superfluidity of harmonically-trapped

polarized ultracold fermionic atoms in a two-dimensional (2D) optical lattice

by solving the Bogoliubov-de Gennes equations. The pairing amplitude is found

to oscillate along the radial direction at low particle density and along the

angular direction at high density. The former is consistent with the existing

experiments and the latter is a newly predicted

Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, which can be tested in

experiments.

\\ ( http://arxiv.org/abs/0710.5484 , 1484kb)

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arXiv:0710.5506

Date: Mon, 29 Oct 2007 19:28:37 GMT (84kb)

Title: An Atom Laser is not monochromatic

Authors: S. Choi, D. Stromberg, and B. Sundaram

Categories: cond-mat.other

Comments: 4 figures. Submitted for publication

\\

We study both numerically and analytically the possibility of using an

adiabatic passage control method to construct a Mach-Zehnder interferometer

(MZI) for Bose-Einstein condensates (BECs) in the time domain, in exact

one-to-one correspondence with the traditional optical MZI that involves two

beam splitters and two mirrors. The interference fringes one obtains from such

a minimum-disturbance set up clearly demonstrates that, fundamentally, an atom

laser is not monochromatic due to interatomic interactions. We also consider

how the amount of entanglement in the system correlates to the interference

fringes.

\\ ( http://arxiv.org/abs/0710.5506 , 84kb)

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arXiv:0710.5397

Date: Mon, 29 Oct 2007 11:52:40 GMT (173kb)

Title: Ground-State Properties for Coupled Bose-Einstein Condensates inside a

Cavity Quantum Electrodynamics

Authors: Gang Chen, Zidong Chen, and J.-Q.Liang

Categories: quant-ph

Report-no: Department of Physics, Shaoxing College of Arts and Sciences,

Shaoxing 312000, People's Republic of China

Journal-ref: EPL, 80 (2007) 40004

\\

We analytically investigate the ground-state properties of two-component

Bose-Einstein condensates with few ⁸⁷Rb atoms inside a high-quality

cavity quantum electrodynamics. In the SU(2) representation for atom, this

quantum system can be realized a generalized Dicke model with a quadratic term

arising from the interatomic interactions, which can be controlled

experimentally by Feshbach resonance technique. Moreover, this weak

interspecies interaction can give rise to an important zero-temperature quantum

phase transition from the normal to the superradiant phases, where the atomic

ensemble in the normal phase is collectively unexcited while is macroscopically

excited with coherent radiations in the superradiant phase. Finally, we propose

to observe this predicted quantum phase transition by measuring the direct and

striking signatures of the photon field in terms of a heterodyne detector out

of the cavity.

\\ ( http://arxiv.org/abs/0710.5397 , 173kb)

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arXiv:0710.5448

Date: Mon, 29 Oct 2007 14:51:22 GMT (32kb)

Title: Exciton-Polariton scattering for defect detection in cold atom Optical

Lattices

Authors: Hashem Zoubi, and Helmut Ritsch

Categories: quant-ph

Comments: 9 pages, 10 figures

\\

We study the effect of defects in the Mott insulator phase of ultracold atoms

in an optical lattice on the dynamics of resonant excitations. Defects, which

can either be empty sites in a Mott insulator state with one atom per site or a

singly occupied site for a filling factor two, change the dynamics of Frenkel

excitons and cavity polaritons. While the vacancies in first case behave like

hard sphere scatters for excitons, singly occupied sites in the latter case can

lead to attractive or repulsive scattering potentials. We suggest cavity

polaritons as observation tool of such defects, and show how the scattering can

be controlled in changing the exciton-photon detuning. In the case of

asymmetric optical lattice sites we present how the scattering effective

potential can be detuned by the cavity photon polarization direction, with the

possibility of a crossover from a repulsive into an attractive potential.

\\ ( http://arxiv.org/abs/0710.5448 , 32kb)

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arXiv:0710.5479

Date: Mon, 29 Oct 2007 16:55:26 GMT (125kb)

Title: A Weyl function approach to matter-wave coherence and Talbot-Lau effects

Authors: Saijun Wu, Pierre S. Striehl, Mara G. Prentiss

Categories: physics.atom-ph

Comments: 38 pages, 17 figures

\\

Weyl functions conveniently describe the evolution of wave coherences in

periodic or quadratic potentials. In this work we use Weyl functions to study

the ``Talbot-Lau effect'' in a time-domain matter-wave interferometer. A

``displacement diagram'' is introduced to analyze and calculate the matter-wave

interference for an atomic cloud in a quadratic potential that interacts with a

sequence of short optical standing wave pulses producing an atomic grating

echo. Unlike previous treatments, this new approach allows the atomic ensemble

to have an arbitrary initial phase-space distribution, and the standing wave

grating vectors to span three dimensions. Several examples are discussed to

illustrate the convenience of the diagrammatic technique including the

following: a two-dimensional Talbot-Lau effect, the shift in the echo time and

the recoil phase for the interferometer perturbed by a quadratic potential; and

the realization of a time-domain ``Lau effect'' using a pulsed harmonic

potential. The diagrammatic technique is applicable to diffraction gratings

with arbitrary grating transmission functions. We conclude the paper with a

general discussion on the Weyl function representations of matter-wave

coherence, and discuss a conservation law that distinguishes decoherence

effects from dephasing effects.

\\ ( http://arxiv.org/abs/0710.5479 , 125kb)

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arXiv:0710.5444

Date: Mon, 29 Oct 2007 14:47:24 GMT (57kb)

Title: Light propagation in atomic Mott Insulators

Authors: Francesco Bariani, Iacopo Carusotto

Categories: physics.optics physics.atom-ph

\\

We study radiation-matter interaction in a system of ultracold atoms trapped

in an optical lattice in a Mott insulator phase. We develop a fully general

quantum model, and we perform calculations for a one-dimensional geometry at

normal incidence. Both two- and three-level $\Lambda$ atomic configurations are

studied. The polariton dispersion and the reflectivity spectra are

characterized in the different regimes, for both semi-infinite and finite-size

geometries. We apply this model to propose a photon energy lifter experiment: a

device which is able to shift the carrier frequency of a slowly travelling

wavepacket without affecting the pulse shape nor its coherence.

\\ ( http://arxiv.org/abs/0710.5444 , 57kb)

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arXiv:0710.5550

Date: Tue, 30 Oct 2007 05:01:10 GMT (142kb)

Title: Vortex lattice transitions in cyclic spinor condensates

Authors: Ryan Barnett, Subroto Mukerjee, Joel E. Moore

Categories: cond-mat.other

Comments: 4 pages, 2 figures

\\

We study the energetics of vortices and vortex lattices produced by rotation

in the cyclic phase of F=2 spinor Bose condensates. In addition to the familiar

triangular lattice predicted by Tkachenko for $^4$He, many more complex

lattices appear in this system as a result of the spin degree of freedom. In

particular, we predict a magnetic-field-driven transition from a triangular

lattice to a honeycomb lattice. Other transitions and lattice geometries are

driven at constant field by changes in the temperature-dependent ratio of

charge and spin stiffnesses, including a transition through an aperiodic vortex

structure.

\\ ( http://arxiv.org/abs/0710.5550 , 142kb)

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arXiv:0710.5610

Date: Tue, 30 Oct 2007 11:06:58 GMT (392kb)

Title: Quantum matter wave dynamics with moving mirrors

Authors: A. del Campo, J. G. Muga, M. Kleber

Categories: quant-ph

Comments: 5.2 pages, 6 figures

\\

When a stationary reflecting wall acting as a perfect mirror for an atomic

beam with well defined incident velocity is suddenly removed, the density

profile develops during the time evolution an oscillatory pattern known as

diffraction in time. The interference fringes are suppressed or their

visibility is diminished by several effects such as averaging over a

distribution of incident velocities, apodization of the aperture function,

atom-atom interactions, imperfect reflection or environmental noise. However,

when the mirror moves with finite velocity along the direction of propagation

of the beam, the visibility of the fringes is enhanced. For mirror velocities

below beam velocity, as used for slowing down the beam, the matter wave splits

into three regions separated by space-time points with classical analogues. For

mirror velocities above beam velocity a visibility enhancement occurs without a

classical counterpart. When the velocity of the beam approaches that of the

mirror the density oscillations rise by a factor 1.8 over the stationary value.

\\ ( http://arxiv.org/abs/0710.5610 , 392kb)

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arXiv:0710.5622

Date: Tue, 30 Oct 2007 12:09:27 GMT (29kb)

Title: Rydberg excitation of Bose-Einstein condensates

Authors: Rolf Heidemann, Ulrich Raitzsch, Vera Bendkowsky, Bj\"orn Butscher,

Robert L\"ow, Tilman Pfau

Categories: quant-ph

Comments: 4 pages, 3 figures

\\

Rydberg atoms provide a wide range of possibilities to tailor interactions in

a quantum gas. Here we report on Rydberg excitation of Bose-Einstein condensed

87Rb atoms. The Rydberg fraction was investigated for various excitation times

and temperatures above and below the condensation temperature. The excitation

is locally blocked by the van der Waals interaction between Rydberg atoms to a

density-dependent limit. Therefore the abrupt change of the thermal atomic

density distribution to the characteristic bimodal distribution upon

condensation could be observed in the Rydberg fraction. The observed features

are reproduced by a simulation based on local collective Rydberg excitations.

\\ ( http://arxiv.org/abs/0710.5622 , 29kb)

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arXiv:0710.5631

Date: Tue, 30 Oct 2007 12:38:06 GMT (63kb,D)

Title: Scheme for implementing atomic multiport devices

Authors: Jacob A. Dunningham

Categories: quant-ph

Comments: 6 pages, 3 figures

\\

Multiport generalizations of beam splitters are an important tool in a range

of quantum information processing protocols. Networks for realising these

devices in optical systems, however, often involve complicated arrangements of

beam splitters and phase plates. This complexity threatens to undermine their

practicality for any more than a few input and output ports. Here we discuss

the case of multiport devices for atoms trapped in optical lattices. We

demonstrate simple schemes for implementing `tritters' and `quarters' and

discuss how these could be combined to create much larger devices with a

substantially lower overhead in atom-optical elements than other proposals.

\\ ( http://arxiv.org/abs/0710.5631 , 63kb)

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arXiv:0710.5798

Date: Wed, 31 Oct 2007 03:06:25 GMT (929kb,D)

Title: Two point correlations of a trapped interacting Bose gas at finite

temperature

Authors: A. Bezett, E. Toth, P. B. Blakie

Categories: cond-mat.other

Comments: 9 pages, 4 figures

\\

We develop a computationally tractable method for calculating correlation

functions of the finite temperature trapped Bose gas that includes the effects

of s-wave interactions. Our approach uses a classical field method to model the

low energy modes and treats the high energy modes using a Hartree-Fock

description. We present results of first and second order correlation

functions, in position and momentum space, for an experimentally realistic

system in the temperature range of $0.6T_c$ to $1.0T_c$. We also characterize

the spatial coherence length of the system. Our theory should be applicable in

the critical region where experiments are now able to measure first and second

order correlations.

\\ ( http://arxiv.org/abs/0710.5798 , 929kb)

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arXiv:0710.5812

Date: Wed, 31 Oct 2007 07:44:10 GMT (94kb)

Title: Anomalous behavior of the spatial pair correlation in a 1D Bose gas

Authors: A. G. Sykes, D. M. Gangardt, M. J. Davis, K. Viering, M. G. Raizen,

and K. V. Kheruntsyan

Categories: cond-mat.other cond-mat.stat-mech

Comments: 4 pages, 2 figures

\\

We analytically calculate the nonlocal pair correlation function for an

interacting uniform 1D Bose gas at finite temperature. Our results span a

number of physical realms, including the weakly and strongly interacting

regimes. We find that under certain conditions the pair correlation may exhibit

a global maximum or minimum at a finite interparticle separations, implying

anomalous, non-monotonic behaviour and the existence of regimes with two

characteristic correlation lengths. We discuss possible experimental methods to

measure the nonlocal pair correlation function.

\\ ( http://arxiv.org/abs/0710.5812 , 94kb)

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arXiv:0710.5819

Date: Wed, 31 Oct 2007 09:03:59 GMT (185kb)

Title: Molecular Formations in Ultra-cold Mixture of Interacting/Noninteracting

Atomic Gases

Authors: T. Nishimura, A. Matsumoto, H. Yabu

Categories: cond-mat.soft cond-mat.other

Comments: 41 pages, 17 figures

\\

Atom-molecule equilibrium for the molecular formation processes are discussed

for the boson-fermion, fermion-fermion and boson-boson mixtures of the

ultra-cold atomic gases in the framework of the quasichemical equilibrium

theory. After the general formulation is given for the molecular

formation/dissociation processes in the quasichemical equilibrium theory,

zero-temperature phase diagrams of the atom-molecule equilibrium states are

calculated analytically; they are shown to involve several phases depending on

the binding energy of the molecules, the molecular, mixed, and dissociated

ones. The temperature-dependences of the atom/molecule densities, which are

calculated numerically, are shown, and they give the finite-temperature phase

structures of the atom-molecule equilibrium in the mixtures. The transition

temperatures of the atom/molecule Bose-Einstein condensations are also

evaluated from these results. The quantum-statistical deviations of the law of

mass action in the atom-molecule equilibrium, which should be satisfied in the

mixtures of the classical Maxwell-Bolzmann gasses, are calculated, and the

difference in the different types of quantum-statistical particles, boson and

fermion, are clarified. Contributions of the interparticle interactions

(atom-atom, atom-molecule, and molecule-molecule) are formulated in the

mean-field approximation; the interaction effects are shown to be included in

the effective molecular binding energies through their linear

density-dependence. The zero-temperature phase diagrams are calculated for the

interacting mixtures, and they are shown to include the phases with coexistent

local-equilibrium states in the case of the strong repulsive interactions.

\\ ( http://arxiv.org/abs/0710.5819 , 185kb)

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arXiv:0710.5921

Date: Wed, 31 Oct 2007 18:24:30 GMT (761kb)

Title: Faraday waves in Bose-Einstein condensates

Authors: Alexandru I. Nicolin, R. Carretero-Gonzalez, and P.G. Kevrekidis

Categories: cond-mat.other

Comments: 10 pages, 9 figures, submitted to Phys. Rev. A

\\

Motivated by recent experiments on Faraday waves in Bose-Einstein condensates

we investigate both analytically and numerically the dynamics of cigar-shaped

Bose-condensed gases subject to periodic modulation of the strength of the

transverse confinement. We offer a fully analytical explanation of the observed

parametric resonance, based on a Mathieu-type analysis of the non-polynomial

Schr{\"o}dinger equation. The theoretical prediction for the pattern

periodicity versus the driving frequency is directly compared with the

experimental data, yielding good qualitative and quantitative agreement between

the two. These results are corroborated by direct numerical simulations of both

the one-dimensional non-polynomial Schr{\"o}dinger equation and of the fully

three-dimensional Gross-Pitaevskii equation.

\\ ( http://arxiv.org/abs/0710.5921 , 761kb)

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\\

arXiv:0711.0029

Date: Wed, 31 Oct 2007 22:35:46 GMT (656kb)

Title: Superfluid and Mott Insulating shells of bosons in harmonically confined

optical lattices

Authors: Kaushik Mitra, C. J. Williams and C. A. R. Sa de Melo

Categories: cond-mat.other

Comments: 11 pages, 9 figures,

\\

Weakly interacting atomic or molecular bosons in quantum degenerate regime

and trapped in harmonically confined optical lattices, exhibit a wedding cake

structure consisting of insulating (Mott) shells. It is shown that superfluid

regions emerge between Mott shells as a result of fluctuations due to finite

hopping. It is found that the order parameter equation in the superfluid

regions is not of the Gross-Pitaeviskii type except near the insulator to

superfluid boundaries. The excitation spectra in the Mott and superfluid

regions are obtained, and it is shown that the superfluid shells posses low

energy sound modes with spatially dependent sound velocity described by a local

index of refraction directly related to the local superfluid density. Lastly,

the Berezinskii-Kosterlitz-Thouless transition and vortex-antivortex pairs are

discussed in thin (wide) superfluid shells (rings) limited by three (two)

dimensional Mott regions.

\\ ( http://arxiv.org/abs/0711.0029 , 656kb)

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\\

arXiv:0711.0088

Date: Thu, 1 Nov 2007 08:51:33 GMT (168kb)

Title: Dynamical Properties of a Rotating Bose-Einstein Condensate

Authors: Sebastian Kling and Axel Pelster

Categories: cond-mat.stat-mech

Comments: Author Information under

http://www.theo-phys.uni-essen.de/tp/ags/pelster_dir

\\

Within a variational approach to solve the Gross-Pitaevskii equation we

investigate dynamical properties of a rotating Bose-Einstein condensate which

is confined in an anharmonic trap. In particular, we calculate the

eigenfrequencies of low-energy excitations out of the equilibrium state and the

aspect ratio of the condensate widths during the free expansion.

\\ ( http://arxiv.org/abs/0711.0088 , 168kb)

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\\

arXiv:0711.0153

Date: Thu, 1 Nov 2007 16:21:55 GMT (62kb)

Title: Matter-wave vortices in cigar-shaped and toroidal waveguides

Authors: Luca Salasnich, Flavio Toigo (CNISM and CNR-INFM, Unita' di Padova,

Dipartimento di Fisica "Galileo Galilei", Universita' di Padova, Via Marzolo

8, Padova, Italy) and Boris A. Malomed (Department of Physical Electronics,

School of Electrical Engineering, Faculty of Engineering, Tel Aviv

University, Tel Aviv, Israel)

Categories: cond-mat.other

Comments: 6 pages, Physical Review A, in press

\\

We study vortical states in a Bose-Einstein condensate (BEC) filling a

cigar-shaped trap. An effective one-dimensional (1D) nonpolynomial Schroedinger

equation (NPSE) is derived in this setting, for the models with both repulsive

and attractive inter-atomic interactions. Analytical formulas for the density

profiles are obtained from the NPSE in the case of self-repulsion within the

Thomas-Fermi approximation, and in the case of the self-attraction as exact

solutions (bright solitons). A crucially important ingredient of the analysis

is the comparison of these predictions with direct numerical solutions for the

vortex states in the underlying 3D Gross-Pitaevskii equation (GPE). The

comparison demonstrates that the NPSE provides for a very accurate

approximation, in all the cases, including the prediction of the stability of

the bright solitons and collapse threshold for them. In addition to the

straight cigar-shaped trap, we also consider a torus-shaped configuration. In

that case, we find a threshold for the transition from the axially uniform

state, with the transverse intrinsic vorticity, to a symmetry-breaking pattern,

due to the instability in the self-attractive BEC filling the circular trap.

\\ ( http://arxiv.org/abs/0711.0153 , 62kb)

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\\

arXiv:0711.0182

Date: Thu, 1 Nov 2007 18:36:30 GMT (110kb)

Title: Spectroscopy and the nature of the ground state of trapped polarized

fermions

Authors: Erich J. Mueller (Cornell)

Categories: cond-mat.other

Comments: 4 Pages, 2 figures, RevTeX4

\\

We show that bimodal radio frequency spectra universally arise at

intermediate temperatures in models of strongly interacting trapped Fermi

gases. The bimodality is independent of superfluidity or pseudogap physics,

depending only on the functional form of the equation of state -- which is

constrained by dimensional analysis at low temperatures and the virial

expansion at high temperatures. In addition to these model independent results,

we present a simple calculation of the radio frequency line-shape of a highly

polarized Fermi gas which uses energetic considerations to include final state

interactions. While this model only qualitatively captures the line-shapes

observed in the experiments, it provides a conceptually clean and powerful

technique for estimating the energy scales and how they vary with experimental

parameters.

\\ ( http://arxiv.org/abs/0711.0182 , 110kb)

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\\

arXiv:0706.3051

Date: Wed, 20 Jun 2007 20:03:04 GMT (378kb)

Title: Molecular Dipolar Crystals as High Fidelity Quantum Memory for Hybrid

Quantum Computing

Authors: P. Rabl and P. Zoller

Categories: quant-ph cond-mat.other

Journal-ref: Phys. Rev. A 76, 042308 (2007)

\\

We study collective excitations of rotational and spin states of an ensemble

of polar molecules, which are prepared in a dipolar crystalline phase, as a

candidate for a high fidelity quantum memory. While dipolar crystals are formed

in the high density limit of cold clouds of polar molecules under 1D and 2D

trapping conditions, the crystalline structure protects the molecular qubits

from detrimental effects of short range collisions. We calculate the lifetime

of the quantum memory by identifying the dominant decoherence mechanisms, and

estimate their effects on gate operations, when a molecular ensemble qubit is

transferred to a superconducting strip line cavity (circuit QED). In the case

rotational excitations coupled by dipole-dipole interactions we identify

phonons as the main limitation of the life time of qubits. We study specific

setups and conditions, where the coupling to the phonon modes is minimized.

Detailed results are presented for a 1D dipolar chain.

\\ ( http://arxiv.org/abs/0706.3051 , 378kb)

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\\

arXiv:0707.4520

Date: Tue, 31 Jul 2007 01:43:15 GMT (21kb)

Title: Correlations Functions of One-Dimensional Lieb-Liniger Anyons

Authors: Ovidiu I. Patu, Vladimir E. Korepin, Dmitri V. Averin

Categories: cond-mat.stat-mech quant-ph

Comments: 19 pages, RevTeX 4

\\

We have investigated the properties of a model of 1D anyons interacting

through a $\delta$-function repulsive potential. The structure of the

quasi-periodic boundary conditions for the anyonic field operators and the

many-anyon wavefunctions is clarified. The spectrum of the low-lying

excitations including the particle-hole excitations is calculated for periodic

and twisted boundary conditions. Using the ideas of the conformal field theory

we obtain the large-distance asymptotics of the density and field correlation

function at the critical temperature T=0 and at small finite temperatures. Our

expression for the field correlation function extends the results in the

literature obtained for harmonic quantum anyonic fluids.

\\ ( http://arxiv.org/abs/0707.4520 , 21kb)

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The replacements:

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\\

arXiv:0710.3094

replaced with revised version Fri, 26 Oct 2007 13:17:46 GMT (38kb)

Title: Effect of the lattice alignment on Bloch oscillations of a Bose-Einstein

condensate in a square optical lattice

Authors: M.-C. Chung and A. R. Kolovsky

Categories: cond-mat.supr-con cond-mat.mes-hall

Comments: 4 pages, 3 figures

\\ ( http://arxiv.org/abs/0710.3094 , 38kb)

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\\

arXiv:cond-mat/0703346

replaced with revised version Mon, 29 Oct 2007 14:36:52 GMT (644kb,D)

Title: Spatial noise correlations of a chain of ultracold fermions - A

numerical study

Authors: Andreas Luscher, Andreas Laeuchli, Reinhard M. Noack

Categories: cond-mat.str-el

Comments: 12 pages, 7 figures

Journal-ref: Phys. Rev. A 76, 043614 (2007)

DOI: 10.1103/PhysRevA.76.043614

\\ ( http://arxiv.org/abs/cond-mat/0703346 , 644kb)

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\\

arXiv:quant-ph/0702193

replaced with revised version Sun, 28 Oct 2007 23:01:34 GMT (181kb)

Title: Light scattering from ultracold atoms in optical lattices as an optical

probe of quantum statistics

Authors: Igor B. Mekhov, Christoph Maschler, Helmut Ritsch

Categories: quant-ph physics.atom-ph physics.optics

Comments: 15 pages, 5 figures

\\ ( http://arxiv.org/abs/quant-ph/0702193 , 181kb)

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\\

arXiv:0710.0692

replaced with revised version Mon, 29 Oct 2007 11:56:28 GMT (362kb)

Title: Entanglement renormalization in fermionic systems

Authors: G. Evenbly, G. Vidal

Categories: quant-ph

Comments: 5 pages, 4 figures Second appendix added

\\ ( http://arxiv.org/abs/0710.0692 , 362kb)

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\\

arXiv:cond-mat/0701198

replaced with revised version Tue, 30 Oct 2007 12:25:23 GMT (75kb)

Title: Flow Equations for the BCS-BEC Crossover

Authors: S. Diehl, H. Gies, J. M. Pawlowski, C. Wetterich

Categories: cond-mat.supr-con cond-mat.stat-mech hep-ph quant-ph

Comments: 4 pages, 4 figures

Report-no: HD-THEP-07-02

Journal-ref: Phys. Rev. A 76, 021602(R) (2007)

\\ ( http://arxiv.org/abs/cond-mat/0701198 , 75kb)

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\\

arXiv:cond-mat/0703366

replaced with revised version Tue, 30 Oct 2007 13:04:15 GMT (75kb)

Title: Renormalisation Flow and Universality for Ultracold Fermionic Atoms

Authors: S. Diehl, H. Gies, J. M. Pawlowski, C. Wetterich

Categories: cond-mat.supr-con cond-mat.stat-mech hep-th quant-ph

Comments: 19 pages, 3 figures, to be published in PRA

\\ ( http://arxiv.org/abs/cond-mat/0703366 , 75kb)

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\\

arXiv:0707.3834

replaced with revised version Mon, 29 Oct 2007 22:44:15 GMT (382kb)

Title: Spin squeezing in optical lattice clocks via lattice-based QND

measurements

Authors: D. Meiser, Jun Ye, and M. J. Holland

Categories: quant-ph physics.atom-ph

Comments: Revised version with expanded introduction and discussion

\\ ( http://arxiv.org/abs/0707.3834 , 382kb)

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\\

arXiv:0710.1033

replaced with revised version Wed, 31 Oct 2007 10:30:32 GMT (120kb)

Title: Dissipation of Quantum Turbulence in the Zero Temperature Limit

Authors: P. M. Walmsley, A. I. Golov, H. E. Hall, A. A. Levchenko and W. F.

Vinen

Categories: cond-mat.other

Comments: 4 pages, 5 figures. Updated following referees comments

\\ ( http://arxiv.org/abs/0710.1033 , 120kb)

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\\

arXiv:0709.3027

replaced with revised version Thu, 1 Nov 2007 18:54:59 GMT (343kb,D)

Title: Phase diagram of a two-component Fermi gas with resonant interactions

Authors: Yong-il Shin, Christian H. Schunck, Andre Schirotzek, Wolfgang

Ketterle

Categories: cond-mat.soft

Comments: 8 pages, 8 figures, reference added, typo corrected

\\ ( http://arxiv.org/abs/0709.3027 , 343kb)

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Till next time,

Matt.

-- ========================================================================= Dr M. J. Davis, Senior Lecturer in Physics School of Physical Sciences, email: mdavis_at_physics.uq.edu.au University of Queensland, ph : +61 7 334 69824 Brisbane, QLD 4072, fax : +61 7 336 51242 Australia. http://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/ ========================================================================= Legal stuff: Unless stated otherwise, this e-mail represents only the views of the sender and not the views of the University of Queensland =========================================================================Received on Wed Nov 28 2007 - 13:10:01 EST

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