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

Date: Fri, 6 Jul 2007 14:24:35 +1000 (EST)

Date: Fri, 6 Jul 2007 14:24:35 +1000 (EST)

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

And you are almost up-to-date: 30 new preprints and 7 replacements last week:

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arXiv:0706.3280

Date: Fri, 22 Jun 2007 11:31:41 GMT (44kb)

Title: Theoretical background for observing ultra-slow microwaves in a

Bose-Einstein condensate of alkali atoms

Authors: Yuriy V. Slyusarenko and Andrey G. Sotnikov

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

Comments: 6 pages, 2 figures

\\

We represent a new microscopic approach that allows studying the propagation

properties of microwaves in a Bose-Einstein condensate of alkali atoms. It is

assumed that the frequency of signal is tuned up to the transition between

hyperfine ground state levels of such atoms. Pulse slowing conditions

dependence on the system parameters is found. It is shown that the slowed

signal can propagate in mentioned system with rather small energy loss. Such

phenomenon is also studied in case of hyperfine levels Zeeman splitting. A

possibility of ultra-slow microwaves observing in a condensed gas of cesium

atoms is discussed.

\\ ( http://arxiv.org/abs/0706.3280 , 44kb)

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arXiv:0706.3360

Date: Fri, 22 Jun 2007 15:02:52 GMT (2160kb)

Title: Theory of ultracold Fermi gases

Authors: Stefano Giorgini, Lev P. Pitaevskii, Sandro Stringari

Categories: cond-mat.other

Comments: 78 pages, 56 figures

\\

The physics of quantum degenerate Fermi gases in uniform as well as in

harmonically trapped configurations is reviewed from a theoretical perspective.

Emphasis is given to the effect of interactions which play a crucial role,

bringing the gas into a superfluid phase at low temperature. In these dilute

systems interactions are characterized by a single parameter, the s-wave

scattering length, whose value can be tuned using an external magnetic field

near a Feshbach resonance. The BCS limit of ordinary Fermi superfluidity, the

Bose-Einstein condensation (BEC) of dimers and the unitary limit of large

scattering length are important regimes exhibited by interacting Fermi gases.

In particular the BEC and the unitary regimes are characterized by a high value

of the superfluid critical temperature, of the order of the Fermi temperature.

Different physical properties are discussed, including the density profiles and

the energy of the ground-state configurations, the momentum distribution, the

fraction of condensed pairs, collective oscillations and pair breaking effects,

the expansion of the gas, the main thermodynamic properties, the behavior in

the presence of optical lattices and the signatures of superfluidity, such as

the existence of quantized vortices, the quenching of the moment of inertia and

the consequences of spin polarization. Various theoretical approaches are

considered, ranging from the mean-field description of the BCS-BEC crossover to

non-perturbative methods based on quantum Monte Carlo techniques. A major goal

of the review is to compare the theoretical predictions with the available

experimental results.

\\ ( http://arxiv.org/abs/0706.3360 , 2160kb)

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arXiv:0706.3361

Date: Fri, 22 Jun 2007 15:46:08 GMT (398kb)

Title: Polarized States and Domain Walls in Spinor Bose-Einstein Condensates

Authors: H.E. Nistazakis, D.J. Frantzeskakis, P.G. Kevrekidis, B.A. Malomed, R.

Carretero-Gonzalez, and A.R. Bishop

Categories: cond-mat.other

Comments: 7 pages, 9 figures, submitted to Phys. Rev. A

\\

We study spin-polarized states and their stability in anti-ferromagnetic

states of spinor (F=1) quasi-one-dimensional Bose-Einstein condensates. Using

analytical approximations and numerical methods, we find various types of

polarized states, including: patterns of the Thomas-Fermi type; structures with

a pulse-shape in one component inducing a hole in the other components; states

with holes in all three components; and domain walls. A Bogoliubov-de Gennes

analysis reveals that families of these states contain intervals of a weak

oscillatory instability, except for the domain walls, which are always stable.

The development of the instabilities is examined by means of direct numerical

simulations.

\\ ( http://arxiv.org/abs/0706.3361 , 398kb)

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arXiv:0706.3376

Date: Fri, 22 Jun 2007 16:40:12 GMT (404kb)

Title: Quantum limited measurements of atomic scattering properties

Authors: A. M. Rey, L. Jiang and M. D. Lukin

Categories: cond-mat.other

Comments: 7 pages, 5 figures

\\

We propose a method to perform precision measurements of the interaction

parameters in systems of N ultra-cold spin 1/2 atoms. The spectroscopy is

realized by first creating a coherent spin superposition of the two relevant

internal states of each atom and then letting the atoms evolve under a

squeezing Hamiltonian. The non-linear nature of the Hamiltonian decreases the

fundamental limit imposed by the Heisenberg uncertainty principle to N^(-2), a

factor of N smaller than the fundamental limit achievable with non-interacting

atoms. We study the effect of decoherence and show that even with decoherence,

entangled states can outperform the signal to noise limit of non-entangled

states. We present two possible experimental implementations of the method

using Bose-Einstein spinor condensates and fermionic atoms loaded in optical

lattices and discuss their advantages and disadvantages.

\\ ( http://arxiv.org/abs/0706.3376 , 404kb)

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arXiv:0706.3378

Date: Fri, 22 Jun 2007 17:13:16 GMT (735kb)

Title: Many-body protected entanglement generation in interacting spin systems

Authors: A. M. Rey, L. Jiang, M. Fleischhauer, E. Demler and M.D. Lukin

Categories: cond-mat.other

Comments: 11 pages, 7 figures. This paper is a longer version of the paper

cond-mat/0703108

\\

We discuss a method to achieve decoherence resistent entanglement generation

in two level spin systems governed by gapped and multi-degenerate Hamiltonians.

In such systems, while the large number of degrees of freedoms in the ground

state levels allows to create various quantum superposition, the energy gap

prevents decoherence as local excitations become energetically suppressed. We

apply the protected evolution to achieve decoherence resistent generation of

many particle GHZ states and show it can significantly increase the sensitivity

in frequency spectroscopy. We discuss how to engineer the desired many-body

protected manifold in two specific physical systems, trapped ions and neutral

atoms in optical lattices, and present simple expressions for the fidelity of

GHZ generation under non-ideal conditions.

\\ ( http://arxiv.org/abs/0706.3378 , 735kb)

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arXiv:0706.3300

Date: Fri, 22 Jun 2007 09:43:14 GMT (16kb)

Title: Trapped Bose gases with large positive scattering length

Authors: M. Th{\o}gersen, D.V. Fedorov, and A.S. Jensen

Categories: quant-ph

\\

We calculate the energy and the condensate fraction of a system of trapped

bosons interacting via a short-range two-body potential with positive

scattering length. The potential is attractive and has a two-body bound state.

When the scattering length is small compared to the trap length the system is

model independent: all potential models -- attractive, repulsive and zero-range

-- provide similar results. When the scattering length is large the attractive

model differs qualitatively from the repulsive and zero-range models. In this

regime the system with attractive potential becomes independent of the

scattering length, with both the energy and the condensate fraction converging

towards finite constants.

\\ ( http://arxiv.org/abs/0706.3300 , 16kb)

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arXiv:0706.3417

Date: Fri, 22 Jun 2007 22:54:40 GMT (28kb)

Title: Superfuid-insulator transitions at non-integer filling in optical

lattices of fermionic atoms

Authors: Chih-Chun Chien, Yan He, Qijin Chen, and K. Levin

Categories: cond-mat.other

Comments: 4 pages, 3 figures

\\

We determine the superfluid transition temperatures $T_c$ and the ground

states of the attractive Hubbard model and find new insulating phases

associated with non-integer filling at sufficiently strong pairing attraction

$|U|$. These states, distinct from the band and Mott insulating phases, derive

from pair localization; pair hopping at large $|U|$ and high densities is

impeded by inter-site, inter-pair repulsive interactions. The best way to

detect the breakdown of superfluidity is using fermionic optical lattices which

should reveal new forms of ``bosonic'' order, reflecting ground state pairing

without condensation.

\\ ( http://arxiv.org/abs/0706.3417 , 28kb)

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arXiv:0706.3458

Date: Mon, 25 Jun 2007 15:29:54 GMT (191kb)

Title: The Thermodynamic Casimir Effect in $^4$He Films near $T_\lambda$: Monte

Carlo Results

Authors: Alfred Hucht

Categories: cond-mat.stat-mech

Comments: 4 pages, 4 figures

\\

The universal finite-size scaling function of the critical Casimir force for

the three dimensional XY universality class with Dirichlet boundary conditions

is determined using Monte Carlo simulations. The results are in excellent

agreement with recent experiments on $^4$He Films at the superfluid transition

and with available theoretical predictions.

\\ ( http://arxiv.org/abs/0706.3458 , 191kb)

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arXiv:0706.3541

Date: Sun, 24 Jun 2007 23:36:46 GMT (43kb)

Title: Beyond Gross-Pitaevskii Mean Field Theory

Authors: N.P. Proukakis

Categories: cond-mat.other

Comments: Review Article (19 Pages) - To appear in 'Emergent Nonlinear

Phenomena in Bose-Einstein Condensates: Theory and Experiment', Edited by

P.G. Kevrekidis, D.J. Frantzeskakis and R. Carretero-Gonzalez (Springer

Verlag)

\\

A large number of effects related to the phenomenon of Bose-Einstein

Condensation (BEC) can be understood in terms of lowest order mean field

theory, whereby the entire system is assumed to be condensed, with thermal and

quantum fluctuations completely ignored. Such a treatment leads to the

Gross-Pitaevskii Equation (GPE) used extensively throughout this book. Although

this theory works remarkably well for a broad range of experimental parameters,

a more complete treatment is required for understanding various experiments,

including experiments with solitons and vortices. Such treatments should

include the dynamical coupling of the condensate to the thermal cloud, the

effect of dimensionality, the role of quantum fluctuations, and should also

describe the critical regime, including the process of condensate formation.

The aim of this Chapter is to give a brief but insightful overview of various

recent theories, which extend beyond the GPE. To keep the discussion brief,

only the main notions and conclusions will be presented. This Chapter

generalizes the presentation of Chapter 1, by explicitly maintaining

fluctuations around the condensate order parameter. While the theoretical

arguments outlined here are generic, the emphasis is on approaches suitable for

describing single weakly-interacting atomic Bose gases in harmonic traps.

Interesting effects arising when condensates are trapped in double-well

potentials and optical lattices, as well as the cases of spinor condensates,

and atomic-molecular coupling, along with the modified or alternative theories

needed to describe them, will not be covered here.

\\ ( http://arxiv.org/abs/0706.3541 , 43kb)

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arXiv:0706.3611

Date: Mon, 25 Jun 2007 10:21:02 GMT (225kb)

Title: Magnetic and superfluid phases of confined fermions in two-dimensional

optical lattices

Authors: Brian M. Andersen and G. M. Bruun

Categories: cond-mat.str-el cond-mat.supr-con

Comments: 4 pages, 3 figures

\\

We examine antiferromagnetic and d-wave superfluid phases of cold fermionic

atoms with repulsive interactions in a two-dimensional optical lattice combined

with a harmonic trapping potential. For experimentally realistic parameters,

the trapping potential leads to the coexistence of magnetic and superfluid

ordered phases with the normal phase. We study the intriguing shell structures

arising from the competition between the magnetic and superfluid order as a

function of the filling fraction. In certain cases antiferromagnetism induce

superfluidity by charge redistributions. We furthermore demonstrate how these

shell structures can be detected as distinct anti-bunching dips and pairing

peaks in the density-density correlation function probed in expansion

experiments.

\\ ( http://arxiv.org/abs/0706.3611 , 225kb)

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arXiv:0706.3617

Date: Mon, 25 Jun 2007 10:53:34 GMT (22kb)

Title: On microscopic theory of spin-S Bose-Einstein condensate in a magnetic

field

Authors: A.S. Peletminskii, S.V. Peletminskii, Yu.V. Slyusarenko

Categories: cond-mat.stat-mech

Comments: 11 pages

Journal-ref: Physica A 380, 202 (2007)

DOI: 10.1016/j.physa.2007.02.107

\\

The Bogoliubov model for weakly interacting Bose gas is extended to

Bose-Einstein condensation (BEC) of spin-S atoms in a magnetic field. Equation

for the vectorial order parameter valid at temperature $T\to 0$ is derived and

its particular solution is found. This solution corresponds to the formation of

BEC of atoms with a definite spin projection onto direction of a magnetic

field. We study the thermodynamic stability of the found solution and obtain

the expressions for low-lying collective modes.

\\ ( http://arxiv.org/abs/0706.3617 , 22kb)

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arXiv:0706.3686

Date: Mon, 25 Jun 2007 18:01:59 GMT (191kb)

Title: Non-equilibrium solid state quantum condensates: the effect of particle

flux on density profiles

Authors: Jonathan Keeling, Natalia G. Berloff

Categories: cond-mat.other

Comments: 5 pages, 4 figures

\\

For a spatially inhomogeneous quantum condensate in the presence of

incoherent particle injection and particle decay, persistent supercurrents

should exist, connecting regions of net gain with regions of net loss, leading

to modifications of the condensate density profile. We model trapped

exciton-polariton condensates by a complex Gross-Pitaevskii (a modified complex

Ginzburg-Landau) equation with pumping and decay and analyse the density and

supercurrents in the ground states. In particular, we show that in some

well-characterized parameter regime the ground state exhibits concentrated

narrow density peaks, as have been observed experimentally in polariton

condensates. We also consider vortex solutions of the system and demonstrate

the effects of superposition of supercurrents.

\\ ( http://arxiv.org/abs/0706.3686 , 191kb)

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arXiv:0706.3411

Date: Fri, 22 Jun 2007 21:13:30 GMT (483kb)

Title: Cavity QED with a Bose-Einstein condensate

Authors: Ferdinand Brennecke, Tobias Donner, Stephan Ritter, Thomas Bourdel,

Michael K\"ohl and Tilman Esslinger

Categories: quant-ph

Comments: 5 pages, 4 figures

\\

Cavity quantum electrodynamics (cavity QED) has proven to be exceedingly

successful in illuminating matter-light interaction and in providing concepts

for quantum information processing. Importantly, by using high-quality

resonators, a strong coupling regime can be reached in which atoms coherently

exchange a photon with one field mode many times before dissipation sets in.

This led to fundamental studies both with microwave and optical resonators. To

meet the challenges posed by quantum state engineering and quantum information

processing, recent experiments have focused on laser cooling and trapping atoms

inside an optical cavity. However, the tremendous advance in the control over

atomic gases achieved with Bose-Einstein condensation has so far not been

utilized for cavity QED. Here we report on the strong coupling of a

Bose-Einstein condensate to the quantized field of an ultrahigh-finesse optical

cavity and present a measurement of its eigenenergy spectrum. A quantitative

analysis reveals that due to the very strong collective coupling higher-order

transverse cavity modes have a significant influence on the spectrum. With this

experiment we enter a conceptually new regime of cavity QED where all atoms

occupy a single mode of a matter-wave field and couple identically to the light

field, sharing a single excitation. This opens possibilities ranging from

quantum communication to a wealth of new phenomena that can be expected in the

many-body physics of quantum gases with cavity mediated interaction.

\\ ( http://arxiv.org/abs/0706.3411 , 483kb)

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arXiv:0706.3649

Date: Mon, 25 Jun 2007 14:10:47 GMT (212kb)

Title: Vacuum Rabi splitting and intracavity dark state in a cavity-atoms

system

Authors: Gessler Hernandez, Jiepeng Zhang, and Yifu Zhu

Categories: physics.optics physics.atom-ph

Comments: 11 pages, 4 figures

\\

We report experimental measurements of the transmission spectrum of an

optical cavity coupled with cold Rb atoms. We observe the multi-atom vacuum

Rabi splitting of a composite cavity and atom system. When a coupling field is

applied to the atoms and induces the resonant two-photon Raman transition with

the cavity field in a Lamda-type three-level system, we observe a cavity

transmission spectrum with two vacuum Rabi sidebands and a central peak

representing the intracavity dark state. The central peak linewidth is

significantly narrowed by the dark-state resonance and its position is

insensitive to the frequency change of the empty cavity.

\\ ( http://arxiv.org/abs/0706.3649 , 212kb)

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arXiv:0706.3719

Date: Tue, 26 Jun 2007 17:05:08 GMT (83kb)

Title: Spectrum and thermal fluctuations of a microcavity polariton

Bose-Einstein condensate

Authors: Davide Sarchi, Vincenzo Savona

Categories: cond-mat.mes-hall cond-mat.other

\\

The Hartree-Fock-Popov theory of interacting Bose particles is developed, for

modeling exciton-polaritons in semiconductor microcavities undergoing

Bose-Einstein condensation. A self-consistent treatment of the linear

exciton-photon coupling and of the exciton non-linearity provides a thermal

equilibrium description of the collective excitation spectrum, of the polariton

energy shifts and of the phase diagram. Quantitative predictions support recent

experimental findings.

\\ ( http://arxiv.org/abs/0706.3719 , 83kb)

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arXiv:0706.3774

Date: Tue, 26 Jun 2007 08:39:16 GMT (69kb)

Title: Superfluid equation of state of dilute composite bosons

Authors: X. Leyronas and R. Combescot

Categories: cond-mat.stat-mech

Comments: 5 pages, 3 figures

\\

We present an exact theory of the BEC-BCS crossover in the BEC regime, which

treats explicitely dimers as made of two fermions. We apply our framework, at

zero temperature, to the calculation of the equation of state. We find that,

when expanding the chemical potential in powers of the density n up to the

Lee-Huang-Yang order, proportional to n^3/2, the result is identical to the one

of elementary bosons in terms of the dimer-dimer scattering length a_M, the

composite nature of the dimers appearing only in the next order term

proportional to n^2 .

\\ ( http://arxiv.org/abs/0706.3774 , 69kb)

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arXiv:0706.3799

Date: Tue, 26 Jun 2007 11:36:50 GMT (160kb)

Title: Mott insulators and correlated superfluids in ultracold Bose-Fermi

mixtures

Authors: F. Hebert, F. Haudin, L. Pollet and G.G. Batrouni

Categories: cond-mat.stat-mech

\\

We study the effects of interaction between bosons and fermions in a

Bose-Fermi mixtures loaded in an optical lattice. We concentrate on the

destruction of a bosonic Mott phase driven by repulsive interaction between

bosons and fermions. Once the Mott phase is destroyed, the system enters a

superfluid phase where the movements of bosons and fermions are correlated. We

show that this phase has simultaneously correlations reminiscent of a

conventional superfluid and of a pseudo-spin density wave order.

\\ ( http://arxiv.org/abs/0706.3799 , 160kb)

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arXiv:0706.3819

Date: Tue, 26 Jun 2007 12:50:55 GMT (13kb)

Title: Condensate Fraction of a Two-Dimensional Attractive Fermi Gas

Authors: Luca Salasnich (CNR-INFM and CNISM, Univ. Padova)

Categories: cond-mat.stat-mech cond-mat.supr-con

Comments: 4 pages, 2 figures, accepted for publication in Phys. Rev. A

\\

We investigate the Bose-Einstein condensation of fermionic pairs in a

two-dimensional uniform two-component Fermi superfluid obtaining an explicit

formula for the condensate density as a function of the chemical potential and

the energy gap. By using the mean-field extended BCS theory, we analyze, as a

function of the bound-state energy, the off-diagonal long-range order in the

crossover from the Bardeen-Cooper-Schrieffer (BCS) state of weakly-bound Cooper

pairs to the Bose-Einstein Condensate (BEC) of strongly-bound molecular dimers.

\\ ( http://arxiv.org/abs/0706.3819 , 13kb)

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arXiv:0706.3869

Date: Tue, 26 Jun 2007 16:39:01 GMT (81kb)

Title: An echo experiment in a strongly interacting Rydberg gas

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

Robert L\"ow, and Tilman Pfau

Categories: quant-ph

Comments: 4 pages, 5 figures

\\

Strong interactions in many-body quantum systems lead to quantum correlations

that typically make it very hard to follow their unitary, i.e., coherent

evolution and distinguish it from incoherent dynamics. When ground state atoms

are excited to a Rydberg state van der Waals interactions among them lead to a

strong suppression of excitation. Despite the strong interactions the evolution

can still be reversed by a simple phase shift in the excitation laser field if

the subsystems behave as effective two level systems, so called `superatoms'

that show a collective dynamics. We experimentally prove the coherence of the

excitation in the strong blockade regime by applying an `optical rotary echo'

technique, in analogy to a method known from nuclear magnetic resonance.

\\ ( http://arxiv.org/abs/0706.3869 , 81kb)

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arXiv:0706.3879

Date: Tue, 26 Jun 2007 17:46:11 GMT (154kb)

Title: Coherent Quantum Optical Control with Sub-wavelength Resolution

Authors: Alexey V. Gorshkov, Liang Jiang, Markus Greiner, Peter Zoller, and

Mikhail D. Lukin

Categories: quant-ph

Comments: 4 pages, 2 figures

\\

We suggest a new method for quantum optical control with nanoscale

resolution. Our method allows for coherent far-field manipulation of individual

quantum systems with spatial selectivity that is not limited by the wavelength

of radiation and can, in principle, approach a few nanometers. The selectivity

is enabled by the nonlinear atomic response, under the conditions of

Electromagnetically Induced Transparency, to a control beam with intensity

vanishing at a certain location. Practical performance of this technique and

its potential applications to quantum information science with cold atoms,

ions, and solid-state qubits are discussed.

\\ ( http://arxiv.org/abs/0706.3879 , 154kb)

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arXiv:0706.3946

Date: Wed, 27 Jun 2007 04:42:00 GMT (163kb)

Title: Phase diagram for a Bose-Einstein condensate moving in an optical

lattice

Authors: Jongchul Mun, Patrick Medley, Gretchen K. Campbell, Luis G. Marcassa,

David E. Pritchard, Wolfgang Ketterle

Categories: cond-mat.other

Comments: 4 figures

\\

The stability of superfluid currents in a system of ultracold bosons was

studied using a moving optical lattice. Superfluid currents in a very weak

lattice become unstable when their momentum exceeds 0.5 recoil momentum.

Superfluidity vanishes already for zero momentum as the lattice deep reaches

the Mott insulator(MI) phase transition. We study the phase diagram for the

disappearance of superfluidity as a function of momentum and lattice depth

between these two limits. Our phase boundary extrapolates to the critical

lattice depth for the superfluid-to-MI transition with 2% precision. When a

one-dimensional gas was loaded into a moving optical lattice a sudden

broadening of the transition between stable and unstable phases was observed.

\\ ( http://arxiv.org/abs/0706.3946 , 163kb)

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arXiv:0706.3995

Date: Wed, 27 Jun 2007 11:04:34 GMT (536kb)

Title: Dynamical instability and dispersion management of an attractive

condensate in an optical lattice

Authors: G. Barontini and M. Modugno

Categories: cond-mat.other

Comments: 5 pages, 4 figures

\\

We investigate the stability of an attractive Bose-Einstein condensate in a

moving 1D optical lattice in the presence of transverse confinement. By means

of a Bogoliubov linear stability analysis we find that the system is

dynamically unstable for low quasimomenta and becomes stable near the band

edge, in a specular fashion with respect to the repulsive case. For low

interactions the instability occurs via long wavelength excitations that are

not sufficient for spoiling the condensate coherence, producing instead an

oscillating density pattern both in real and momentum space. This behaviour is

illustrated by simulations for the expansion of the condensate in a moving

lattice.

\\ ( http://arxiv.org/abs/0706.3995 , 536kb)

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arXiv:0706.4000

Date: Wed, 27 Jun 2007 11:31:30 GMT (10kb)

Title: Effective field theory and cold Fermi gases near unitary limit

Authors: Boris Krippa

Categories: cond-mat.supr-con

Comments: 7 pages, 1 figure

\\

We study a dynamics of ultracold Fermi-gases near the unitary limit in the

framework of Effective Field Theory. It is shown that, while one can obtain a

reasonable description of the universal proportionality constant both in the

narrow and the broad Feshbach resonance limits, the reguirement of the

reparametrisation invariance leads to appearance of the three body forces

needed to cancel the otherwise arising off-shell uncertainties. The size of the

unsertainties is estimated.

\\ ( http://arxiv.org/abs/0706.4000 , 10kb)

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arXiv:0706.4041

Date: Wed, 27 Jun 2007 14:47:56 GMT (776kb)

Title: Matter-wave Interferometry with Phase Fluctuating Bose-Einstein

Condensates

Authors: G.-B. Jo, J.-H. Choi, C.A. Christensen, Y.-R. Lee, T.A. Pasquini, W.

Ketterle, and D.E. Pritchard

Categories: cond-mat.other

Comments: 4 pages, 5 figures

\\

Elongated Bose-Einstein condensates (BECs) exhibit strong spatial phase

fluctuations even well below the BEC transition temperature. We demonstrate

that atom interferometers using such condensates are robust against phase

fluctuations, i.e. the relative phase of the split condensate is reproducible

despite axial phase fluctuations. However, larger phase fluctuations limit the

coherence time, especially in the presence of some asymmetries in the two wells

of the interferometer.

\\ ( http://arxiv.org/abs/0706.4041 , 776kb)

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arXiv:0706.4085

Date: Wed, 27 Jun 2007 19:52:25 GMT (20kb)

Title: A new effective interaction for the trapped Fermi gas

Authors: Y. Alhassid, G.F. Bertsch, L. Fang

Categories: cond-mat.other

Comments: 4 pages, 3 figures

\\

We apply the configuration-interaction method to calculate the spectra of

two-component Fermi systems in a harmonic trap, studying the convergence of the

method at the unitary interaction limit. We find that for a fixed

regularization of the two-body interaction the convergence is exponential or

better in the truncation parameter of the many-body space. However, the

conventional regularization is found to have poor convergence in the

regularization parameter, with an error that scales as a low negative power of

this parameter. We propose a new regularization of the two-body interaction

that produces exponential convergence for systems of three and four particles.

From the systematics, we estimate the ground-state energy of the

four-particle system to be (5.05 +- 0.024)hbar omega.

\\ ( http://arxiv.org/abs/0706.4085 , 20kb)

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arXiv:0706.4123

Date: Thu, 28 Jun 2007 00:22:57 GMT (807kb)

Title: Level crossing in the three-body problem for strongly interacting

fermions in a harmonic trap

Authors: J. P. Kestner, L.-M. Duan

Categories: cond-mat.other

Comments: 5 pages, 6 figures

\\

We present a solution of the three-fermion problem in a harmonic potential

across a Feshbach resonance. We compare the spectrum with that of the two-body

problem and show that it is energetically unfavorable for three fermions to

occupy one lattice site rather than two. We also demonstrate the existence of

an energy level crossing in the ground state with a symmetry change of its wave

function, suggesting the possibility of a phase transition for the

corresponding many-body case.

\\ ( http://arxiv.org/abs/0706.4123 , 807kb)

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arXiv:0706.4218

Date: Thu, 28 Jun 2007 12:55:05 GMT (169kb)

Title: Association of heteronuclear molecules in a harmonic oscillator well

Authors: Jesper Fevre Bertelsen and Klaus Molmer

Categories: cond-mat.other

Comments: 10 pages, 4 figures

\\

We describe the collisional interaction between two different atoms that are

trapped in a harmonic potential. The atoms are exposed to a magnetic field,

which is modulated in the vicinity of an s-wave Feshbach resonance, and we

study the formation of molecular bound states and excited states of the trapped

system with non-trivial angular correlations.

\\ ( http://arxiv.org/abs/0706.4218 , 169kb)

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arXiv:0706.4260

Date: Thu, 28 Jun 2007 15:46:41 GMT (384kb)

Title: Ultracold Bose gases in time-dependent 1D superlattices: response and

quasimomentum structure

Authors: Markus Hild, Felix Schmitt, Ilona T\"urschmann, Robert Roth

Categories: cond-mat.stat-mech

Comments: 4 pages, 4 figures

\\

The response of ultracold atomic Bose gases in time-dependent optical

lattices is discussed based on direct simulations of the time-evolution of the

many-body state in the framework of the Bose-Hubbard model. We focus on

small-amplitude modulations of the lattice potential as implemented in several

recent experiment and study different observables in the region of the first

resonance in the Mott-insulator phase. In addition to the energy transfer we

investigate the quasimomentum structure of the system which is accessible via

the matter-wave interference pattern after a prompt release. We identify

characteristic correlations between the excitation frequency and the

quasimomentum distribution and study their structure in the presence of a

superlattice potential.

\\ ( http://arxiv.org/abs/0706.4260 , 384kb)

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arXiv:0706.4149

Date: Thu, 28 Jun 2007 06:04:14 GMT (221kb)

Title: Integrating cavity quantum electrodynamics and ultracold-atom chips with

on-chip dielectric mirrors and temperature stabilization

Authors: T.P. Purdy, D.M. Stamper-Kurn

Categories: quant-ph

Comments: 5 pages, 4 figures

\\

We have fabricated an atom chip device which combines the circuitry for

magnetic trapping of cold atoms with high-finesse optical resonators suitable

for cavity QED in the single-atom strong coupling regime. Fabry-Perot optical

resonators with finesse F > 2 X 10^5 were formed between a micropatterned

on-chip planar mirror with lateral dimension of < 100 um and a curved mirror

suspended above the chip. The strong and rapid thermal coupling between on-chip

electrical and optical elements was utilized to stabilize the cavity mirror

separation with servo bandwidth exceeding 100 kHz during simulated operation of

the atom chip.

\\ ( http://arxiv.org/abs/0706.4149 , 221kb)

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arXiv:0706.4159

Date: Thu, 28 Jun 2007 07:50:25 GMT (45kb)

Title: Multimode analysis of the light emitted from a pulsed optical parametric

oscillator

Authors: Anne E. B. Nielsen and Klaus Molmer

Categories: quant-ph

Comments: 10 pages, 6 figures

\\

We present a multimode treatment of the optical parametric oscillator, which

is valid for both pulsed and continuous-wave pump fields. The two-time

correlation functions of the output field are derived, and we apply the theory

to analyze a scheme for heralded production of non-classical field states that

may be subsequently stored in an atomic quantum memory.

\\ ( http://arxiv.org/abs/0706.4159 , 45kb)

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The replacments:

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arXiv:0705.2027

replaced with revised version Fri, 22 Jun 2007 14:18:56 GMT (199kb)

Title: Measuring Electric Fields From Surface Contaminants with Neutral Atoms

Authors: J.M. Obrecht, R.J. Wild, E.A. Cornell

Categories: cond-mat.soft physics.atom-ph

Comments: 7 pages, 6 figures, published in Physical Review A

Journal-ref: Phys. Rev. A 75, 062903 (2007)

DOI: 10.1103/PhysRevA.75.062903

\\ ( http://arxiv.org/abs/0705.2027 , 199kb)

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arXiv:cond-mat/0702178

replaced with revised version Fri, 22 Jun 2007 13:16:34 GMT (250kb)

Title: Excited Thomas-Efimov levels in ultracold gases

Authors: Mark D. Lee, Thorsten Koehler, Paul S. Julienne

Categories: cond-mat.other

Comments: 17 pages, 10 eps figures

\\ ( http://arxiv.org/abs/cond-mat/0702178 , 250kb)

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arXiv:cond-mat/0703443

replaced with revised version Fri, 22 Jun 2007 09:42:00 GMT (149kb)

Title: Spectral properties of a Rydberg atom immersed in a Bose-Einstein

condensate

Authors: Stephan Middelkamp, Igor Lesanovsky, and P. Schmelcher

Categories: cond-mat.other

\\ ( http://arxiv.org/abs/cond-mat/0703443 , 149kb)

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arXiv:physics/0612143

replaced with revised version Fri, 22 Jun 2007 12:26:29 GMT (138kb)

Title: Dynamical interferences to probe short-pulse photoassociation of Rb

atoms and stabilization of Rb_2 dimers

Authors: Jordi Mur-Petit, Eliane Luc-Koenig, Fran\c{c}oise Masnou-Seeuws

Categories: physics.atom-ph cond-mat.other quant-ph

Comments: 4 pages, 5 figures. v2: major changes in introduction, discussion

clarified. v3: minor corrections. v4: matches published version

Journal-ref: Phys. Rev. A 75, 061404(R) (2007)

DOI: 10.1103/PhysRevA.75.061404

\\ ( http://arxiv.org/abs/physics/0612143 , 138kb)

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arXiv:cond-mat/0702649

replaced with revised version Sun, 24 Jun 2007 06:34:32 GMT (995kb)

Title: Quantum dynamics of Raman-coupled Bose-Einstein condensates using

Laguerre-Gaussian beams

Authors: Rina Kanamoto, Ewan M. Wright, Pierre Meystre

Categories: cond-mat.other

Comments: 10 pages, 6 figures

Journal-ref: Phys. Rev. A 75, 063623 (2007)

\\ ( http://arxiv.org/abs/cond-mat/0702649 , 995kb)

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arXiv:cond-mat/0702067

replaced with revised version Tue, 26 Jun 2007 18:55:08 GMT (203kb)

Title: Time-dependent quantum many-body theory of identical bosons in a double

well: Early time ballistic interferences of fragmented and number entangled

states

Authors: David J. Masiello, William P. Reinhardt

Categories: cond-mat.other

Comments: 16 pages, 5 figures

\\ ( http://arxiv.org/abs/cond-mat/0702067 , 203kb)

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arXiv:cond-mat/0702269

replaced with revised version Thu, 28 Jun 2007 09:34:35 GMT (967kb)

Title: Off-diagonal long-range order, cycle probabilities, and condensate

fraction in the ideal Bose gas

Authors: Maguelonne Chevallier, Werner Krauth

Categories: cond-mat.stat-mech

Comments: 6 pages, extensive rewriting, new section on maximum-length cycles

\\ ( http://arxiv.org/abs/cond-mat/0702269 , 967kb)

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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 Fri Jul 06 2007 - 14:24:35 EST

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