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

Date: Mon, 10 Jul 2006 09:35:38 +1000 (EST)

Date: Mon, 10 Jul 2006 09:35:38 +1000 (EST)

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

Hi all,

Lots of interesting looking papers this week. One that caught my eye in

particular was a Fermi gas released into an optical lattice by the Ketterle

group, and subsequent inference of superfluidity.

This email service will be slightly irregular for the next few weeks as I travel

about Europe, starting with attending ICAP 2006 in Innsbruck next week. If you

find these emails useful and happen to run into me, do say hello! Positive

feedback will help keep me motivated (as well as good Austrian beer.) :)

On with the abstracts:

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Paper: cond-mat/0606815

Date: Fri, 30 Jun 2006 15:53:12 GMT (271kb)

Title: Localized modes in arrays of boson-fermion mixtures

Authors: Yu. V. Bludov, V. V. Konotop

Subj-class: Other

\\

It is shown that the mean-field description of a boson-fermion mixture with a

dominating fermionic component, loaded in a one-dimensional optical lattice, is

reduced to the nonlinear Schr\"{o}dinger equation with a periodic potential and

periodic nonlinearity. In such system there exist localized modes having

peculiar properties. In particular, for some regions of parameters there exists

a lower bound for a number of atoms necessary for creation of a mode, while for

other domains small amplitude gap solitons are not available in vicinity of

either of the gap edges. We found that the lowest branch of the symmetric

solution may either exist only for a restricted range of energies in a gap or

does not exist, unlike in pure bosonic condensates. The simplest bifurcations

of the modes are shown and stability of the modes is verified numerically.

\\ ( http://arXiv.org/abs/cond-mat/0606815 , 271kb)

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Paper: cond-mat/0512018

replaced with revised version Fri, 30 Jun 2006 08:37:55 GMT (201kb)

Title: Fourier synthesis of optical potentials for atomic quantum gases

Authors: Gunnar Ritt, Carsten Geckeler, Tobias Salger, Giovanni Cennini, Martin

Weitz

Comments: 4 figures

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0512018 , 201kb)

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Paper: cond-mat/0601147

replaced with revised version Fri, 30 Jun 2006 07:21:19 GMT (889kb)

Title: LOFF Pairing vs. Breached Pairing in Asymmetric Fermion Superfluids

Authors: Lianyi He, Meng Jin and Pengfei Zhuang

Comments: 12 pages, 13 figures, published in Physical Review B. Notice: an

algebra error in Equation (39) corrected

Subj-class: Superconductivity

Journal-ref: Phys. Rev. B73, 214527(2006)

\\ ( http://arXiv.org/abs/cond-mat/0601147 , 889kb)

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Paper: cond-mat/0604216

replaced with revised version Fri, 30 Jun 2006 03:49:09 GMT (68kb)

Title: Optimal conversion of Bose condensed atoms into molecules via a Feshbach

resonance

Authors: Jaeyoon Jeong, Chris P. Search, and Ivana Djuric

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0604216 , 68kb)

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Paper: cond-mat/0605038

replaced with revised version Fri, 30 Jun 2006 18:44:20 GMT (77kb)

Title: The evolution of additional (hidden) quantum variables in the

interference of Bose-Einstein condensates

Authors: W. J. Mullin, R. Krotkov, and F. Lalo\"{e}

Comments: 27 pages, 7 figures

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0605038 , 77kb)

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Paper: quant-ph/0511222

replaced with revised version Thu, 29 Jun 2006 23:00:54 GMT (18kb)

Title: Proposal of an experimentally accessible measure of many-fermion

entanglement

Authors: M. Kindermann

Comments: 5 pages, 3 figures, published version

Subj-class: Quantum Physics; Mesoscopic Systems and Quantum Hall Effect

Journal-ref: Phys. Rev. Lett. 96, 240403 (2006)

\\ ( http://arXiv.org/abs/quant-ph/0511222 , 18kb)

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Paper: quant-ph/0606246

Date: Thu, 29 Jun 2006 20:09:50 GMT (67kb)

Title: Stochastic Schroedinger equation from optimal observable evolution

Authors: Denis Lacroix

Comments: 13 pages, 1 figure

\\

In this article, we consider a set of trial wave-functions denoted by $| Q

\right>$ and an associated set of operators $A_\alpha$ which generate

transformations connecting those trial states. Using variational principles, we

show that we can always obtain a quantum Monte-Carlo method where the quantum

evolution of a system is replaced by jumps between density matrices of the form

$D = |Q_a> <Q_b|$, and where the average evolutions of the moments of

$A_\alpha$ up to a given order $k$, i.e. $< A_{\alpha_1} >$, $< A_{\alpha_1}

A_{\alpha_2} >$,..., $< A_{\alpha_1} ... A_{\alpha_k} >$, are constrained to

follow the exact Ehrenfest evolution at each time step along each stochastic

trajectory. Then, a set of more and more elaborated stochastic approximations

of a quantum problem is obtained which approach the exact solution when more

and more constraints are imposed, i.e. when $k$ increases. The Monte-Carlo

process might even become exact if the Hamiltonian $H$ applied on the trial

state can be written as a polynomial of $A_\alpha$. The formalism makes a

natural connection between quantum jumps in Hilbert space and phase-space

dynamics. We show that the derivation of stochastic Schroedinger equations can

be greatly simplified by taking advantage of the existence of this hierarchy of

approximations and its connection to the Ehrenfest theorem. Several examples

are illustrated: the free wave-packet expansion, the Kerr oscillator, a

generalized version of the Kerr oscillator, as well as interacting bosons or

fermions.

\\ ( http://arXiv.org/abs/quant-ph/0606246 , 67kb)

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Paper: quant-ph/0606247

Date: Fri, 30 Jun 2006 10:25:55 GMT (780kb)

Title: Experimental evidence for the breakdown of a Hartree-Fock approach in a

weakly interacting Bose gas

Authors: Jean-Baptiste Trebbia (LCFIO), J\'{e}r\^{o}me Est\`{e}ve (LCFIO),

Christoph I. Westbrook (LCFIO), Isabelle Bouchoule (LCFIO)

Comments: submitted to Phys. Rev. Letters

Proxy: ccsd ccsd-00083391

\\

We study the formation of a quasi-condensate in a nearly one dimensional,

weakly interacting trapped atomic Bose gas. We show that a Hartree Fock

(mean-field) approach fails to explain the presence of the quasi-condensate in

the center of the cloud: the quasi-condensate appears through an

interaction-driven cross-over and not a saturation of the excited states.

Numerical calculations based on Bogoliubov theory give an estimate of the

cross-over density in agreement with experimental results.

\\ ( http://arXiv.org/abs/quant-ph/0606247 , 780kb)

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Paper: quant-ph/0606249

Date: Fri, 30 Jun 2006 18:57:20 GMT (163kb)

Title: Direct measurement of decoherence for entanglement between a photon and

stored atomic excitation

Authors: H. de Riedmatten, J. Laurat, C.W. Chou, E.W. Schomburg, D. Felinto and

H.J. Kimble

Comments: 5 pages, 3 figures

\\

Violations of a Bell inequality are reported for an experiment where one of

two entangled qubits is stored in a collective atomic memory for a user-defined

time delay. The atomic qubit is found to preserve the violation of a Bell

inequality for storage times up to 21 microseconds, 700 times longer than the

duration of the excitation pulse that creates the entanglement. To address the

question of the security of entanglement-based cryptography based upon this

system, an investigation of the Bell violation as a function of the

cross-correlation between the generated nonclassical fields is reported, with

saturation of the violation close to the maximum value allowed by quantum

mechanics.

\\ ( http://arXiv.org/abs/quant-ph/0606249 , 163kb)

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Paper: quant-ph/0512226

replaced with revised version Fri, 30 Jun 2006 14:33:52 GMT (355kb)

Title: Efficient quantum memory and entanglement between light and an atomic

ensemble using magnetic fields

Authors: Christine A. Muschik, Klemens Hammerer, Eugene S. Polzik, J. Ignacio

Cirac

Journal-ref: Phys. Rev. A 73 062329 (2006)

\\ ( http://arXiv.org/abs/quant-ph/0512226 , 355kb)

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Paper: quant-ph/0603156

replaced with revised version Fri, 30 Jun 2006 12:04:40 GMT (19kb)

Title: Implementing 1 Dimensional Quantum (Hadamard) Walk using Bose-Einstein

Condensate

Authors: C.M. Chandrashekar

Comments: 6 pages, 3 figures

\\ ( http://arXiv.org/abs/quant-ph/0603156 , 19kb)

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Paper: physics/0606257

Date: Fri, 30 Jun 2006 01:55:06 GMT (722kb)

Title: Nonlinear magneto-optical rotation with modulated light in tilted

magnetic fields

Authors: S. Pustelny, S. M. Rochester, D. F. Jackson Kimball, V. V. Yashchuk,

D. Budker, W. Gawlik

Comments: Submitted to Phys. Rev. A, 6 pages, 9 figures

Subj-class: Atomic Physics; Optics

\\

Larmor precession of laser-polarized atoms contained in

anti-relaxation-coated cells, detected via nonlinear magneto-optical rotation

(NMOR) is a promising technique for a new generation of ultra-sensitive atomic

magnetometers. For magnetic fields directed along the light propagation

direction, resonances in NMOR appear when linearly polarized light is

frequency- or amplitude-modulated at twice the Larmor frequency. Because the

frequency of these resonances depends on the magnitude but not the direction of

the field, they are useful for scalar magnetometry. New NMOR resonances at the

Larmor frequency appear when the magnetic field is tilted away from the light

propagation direction in the plane defined by the light propagation and

polarization vectors. These new resonances, studied both experimentally and

with a density matrix calculation in the present work, offer a convenient

method for NMOR-based vector magnetometry.

\\ ( http://arXiv.org/abs/physics/0606257 , 481kb)

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Paper: cond-mat/0607004

Date: Mon, 3 Jul 2006 18:16:28 GMT (390kb)

Title: Superfluidity of Ultracold Fermions in an Optical Lattice

Authors: J. K. Chin, D. E. Miller, Y. Liu, C. Stan, W. Setiawan, C. Sanner, K.

Xu, W. Ketterle

Subj-class: Other

\\

The study of superfluid fermion pairs in a crystalline potential has

important ramifications for understanding superconductivity in many materials.

By simulating such systems using cold atomic gases, various condensed matter

models can be studied in a highly controllable environment. Here we show that

when a condensate of fermionic atom pairs was released from an optical lattice,

distinct interference peaks appear, implying long range order and

superfluidity. These observations were made for unitarity limited interactions

on both sides of a Feshbach resonance. For larger lattice depths, the coherence

was lost in a reversible manner. Such strongly interacting fermions in an

optical lattice can be used to study a new class of Hamiltonians with interband

and atom-molecule couplings.

\\ ( http://arXiv.org/abs/cond-mat/0607004 , 390kb)

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Paper: cond-mat/0607045

Date: Mon, 3 Jul 2006 13:38:52 GMT (54kb)

Title: Bogoliubov theory of Feshbach molecules in the BEC-BCS crossover

Authors: M. W. J. Romans and H. T. C. Stoof

Comments: 13 pages of RevTex and 12 Figures. Submitted for publication in

Physical review A

Subj-class: Statistical Mechanics; Superconductivity

\\

We present the Bogoliubov theory for the Bose-Einstein condensation of

Feshbach molecules in a balanced Fermi mixture. Because the Bogoliubov theory

includes (Gaussian) fluctuations, we can in this manner accurately incorporate

both the two-body and many-body aspects of the BEC-BCS crossover that occurs

near a Feshbach resonance. We apply the theory in particular to the very broad

Feshbach resonance in atomic Li-6 at a magnetic field of B_0 = 834 G and find

good agreement with experiments in that case. The BEC-BCS crossover for more

narrow Feshbach resonances is also discussed.

\\ ( http://arXiv.org/abs/cond-mat/0607045 , 54kb)

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Paper (*cross-listing*): quant-ph/0406095

Date: Mon, 14 Jun 2004 19:46:50 GMT (17kb)

Title: On interacting fermions and bosons with definite total momentum

Authors: Ofir E. Alon, Alexej I. Streltsov, and Lorenz S. Cederbaum

Categories: quant-ph

Subj-class: Quantum Physics; Other

Journal-ref: Phys. Rev. B 71, 125113 (2005)

\\

Any {\it exact} eigenstate with a definite momentum of a many-body

Hamiltonian can be written as an integral over a {\it symmetry-broken} function

$\Phi$. For two particles, we solve the problem {\it exactly} for all energy

levels and any inter-particle interaction. Especially for the ground-state,

$\Phi$ is given by the simple Hartree-Fock/Hartree ansatz for fermions/bosons.

Implications for several and many particles as well as a numerical example are

provided.

\\ ( http://arXiv.org/abs/quant-ph/0406095 , 17kb)

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Paper: cond-mat/0602437

replaced with revised version Mon, 3 Jul 2006 05:40:06 GMT (187kb)

Title: Phase diagrams of one-dimensional Bose-Fermi mixtures of ultra-cold

atoms

Authors: L. Mathey, D.-W. Wang

Comments: 16 pages, 8 figures, v2: minor changes

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0602437 , 187kb)

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Paper: cond-mat/0604625

replaced with revised version Mon, 3 Jul 2006 16:35:25 GMT (493kb)

Title: Signatures of the superfluid to Mott-insulator transition in the

excitation spectrum of ultracold atoms

Authors: S.R. Clark and D. Jaksch

Comments: 18 pages and 12 figures; Some improved results and additional

references. To appear in a special issue of New J. Phys

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0604625 , 493kb)

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Paper: quant-ph/0601137

replaced with revised version Mon, 3 Jul 2006 09:51:41 GMT (466kb)

Title: Theoretical study of a cold atom beam splitter

Authors: Naceur Gaaloul (PPM, LSAMA), Annick Suzor-Weiner (PPM), Laurence

Pruvost (LAC), Mourad Telmini (LSAMA), Eric Charron (PPM)

Proxy: ccsd ccsd-00017414

\\ ( http://arXiv.org/abs/quant-ph/0601137 , 466kb)

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Paper: physics/0607008

Date: Sun, 2 Jul 2006 23:27:32 GMT (51kb)

Title: Study of Degeneracy Three Fermi Fluid

Authors: S. Y. Chang V. R. Pandharipande

Comments: 6 figures, 1 table

Subj-class: Atomic Physics

\\

We present an analysis of the three species or degeneracy three Fermi fluid.

Strongly interacting three component Fermi fluid could be realized

experimentally with the spin polarized states of $^6$Li and broad and close

lying Feshbach resonances. At high enough trapping field, the electron spin is

polarized and the internal degrees of freedom are given by the nuclear spin

projection. For $^6$Li the nuclear angular momentum $I = 1$ can support three

Zeeman states such that s-wave interaction becomes possible for atoms occupying

different states. We estimate the threshold of the three body binding using

numerical and dimensional arguments. This threshold s-wave scattering length

depends on the range, unlike the two body case. We find that the

pseudo-potential approximation does not provide accurate description of the

degeneracy three Fermi fluid. We also explore superfluidity through broken

symmetry pairing between two of the fermion species.

\\ ( http://arXiv.org/abs/physics/0607008 , 51kb)

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Paper: cond-mat/0607060

Date: Mon, 3 Jul 2006 20:04:48 GMT (22kb)

Title: Dissipation-managed soliton in a quasi-one-dimensional Bose-Einstein

condensate

Authors: Sadhan K. Adhikari

Comments: 5 pages, 3 figures

Subj-class: Other

\\

We use the time-dependent mean-field Gross-Pitaevskii equation to study the

formation of a dynamically-stabilized dissipation-managed bright soliton in a

quasi-one-dimensional Bose-Einstein condensate (BEC). Because of three-body

recombination of bosonic atoms to molecules, atoms are lost (dissipated) from a

BEC. Such dissipation leads to the decay of a BEC soliton. We demonstrate by a

perturbation procedure that an alimentation of atoms from an external source to

the BEC may compensate for the dissipation loss and lead to a

dynamically-stabilized soliton. The result of the analytical perturbation

method is in excellent agreement with mean-field numerics. It seems possible to

obtain such a dynamically-stabilized BEC soliton without dissipation in

laboratory.

\\ ( http://arXiv.org/abs/cond-mat/0607060 , 22kb)

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Paper: cond-mat/0607068

Date: Tue, 4 Jul 2006 08:02:45 GMT (725kb)

Title: Gap solitons in quasiperiodic optical lattices

Authors: Hidetsugu Sakaguchi and Boris A. Malomed

Comments: 8 pages, 11 figures

Subj-class: Soft Condensed Matter; Statistical Mechanics

\\

Families of solitons in one- and two-dimensional (1D and 2D) Gross-Pitaevskii

equations with the repulsive nonlinearity and a potential of the

quasicrystallic type are constructed (in the 2D case, the potential corresponds

to a five-fold optical lattice). Stable 1D solitons in the weak potential are

explicitly found in three bandgaps. These solitons are mobile, and they collide

elastically. Many species of tightly bound 1D solitons are found in the strong

potential, both stable and unstable (unstable ones transform themselves into

asymmetric breathers). In the 2D model, families of both fundamental and

vortical solitons are found and are shown to be stable.

\\ ( http://arXiv.org/abs/cond-mat/0607068 , 725kb)

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Paper: cond-mat/0607091

Date: Tue, 4 Jul 2006 18:20:35 GMT (243kb)

Title: Tuning of heteronuclear interactions in a quantum-degenerate Fermi-Bose

mixture

Authors: S. Ospelkaus, C. Ospelkaus, L. Humbert, K. Sengstock, and K. Bongs

Comments: 4 pages, 4 figures

Subj-class: Statistical Mechanics

\\

We demonstrate tuning of interactions between fermionic 40K and bosonic 87Rb

atoms by Feshbach resonances and access the complete phase diagram of the

harmonically trapped mixture from phase separation to collapse. On the

attractive side of the resonance, we observe a strongly enhanced mean-field

energy of the condensate due to the mutual mean-field confinement, predicted by

a Thomas-Fermi model. As we increase heteronuclear interactions beyond a

threshold, we observe an induced collapse of the mixture. On the repulsive side

of the resonance, we observe vertical phase separation of the mixture in the

presence of the gravitational force, thus entering a completely unexplored part

of the phase diagram of the mixture. In addition, we identify the 515 G

resonance as p-wave by its characteristic doublet structure.

\\ ( http://arXiv.org/abs/cond-mat/0607091 , 243kb)

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Paper (*cross-listing*): cond-mat/0606743

Date: Thu, 29 Jun 2006 03:37:03 GMT (19kb)

Title: Predicted quantum stripe ordering in optical lattices

Authors: Congjun Wu, W. Vincent Liu, Joel Moore, and Sankar Das Sarma

Comments: 5 pages, two figures

Subj-class: Strongly Correlated Electrons; Superconductivity

\\

We predict the robust existence of a novel quantum orbital stripe order in

the $p$-band Bose-Hubbard model of two-dimensional triangular optical lattices

with cold bosonic atoms. An orbital angular momentum moment is formed on each

site exhibiting a stripe order both in the superfluid and Mott-insulating

phases. The stripe order spontaneously breaks time-reversal, lattice

translation and rotation symmetries. In addition, it induces staggered

plaquette bond currents in the superfluid phase. Possible signatures of this

stripe order in the time of flight experiment are discussed.

\\ ( http://arXiv.org/abs/cond-mat/0606743 , 19kb)

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Paper: cond-mat/0607098

Date: Wed, 5 Jul 2006 01:33:10 GMT (10kb)

Title: Critical velocities for a superfluid in a periodic potential

Authors: Biao Wu and Junren Shi

Comments: 3 pages, 1 figure

Subj-class: Superconductivity

\\

In contrast to the homogeneous superfluid which has only one critical

velocity, there exist two critical velocities for a superfluid in a periodic

potential. The first one, which we call inside critical velocity, is for a

macroscopic impurity to move frictionlessly in the periodic superfluid system;

the second, which is called trawler critical velocity, is the largest velocity

of the lattice relative to the lab frame for the superfluidity to maintain. The

results are relevant to the superfluidity observed in the Bose-Einstein

condensate in an optical lattice and supersolid helium.

\\ ( http://arXiv.org/abs/cond-mat/0607098 , 10kb)

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Paper: cond-mat/0607101

Date: Wed, 5 Jul 2006 06:02:56 GMT (171kb)

Title: Condensation of N bosons IV: A simplified Bogoliubov master equation

analysis of fluctuations in an interacting Bose gas

Authors: Marlan O. Scully, Anatoly A. Svidzinsky

Comments: 11 pages, 5 figures, to appear in JMO

Subj-class: Statistical Mechanics

\\

A nonequilibrium master equation analysis for N interacting bosons, with

Bogoliubov quasiparticles as the reservoir is presented. The analysis is based

on a simplified Hamiltonian. The steady state solution yields the equilibrium

density matrix. The results are in good agreement with and extend our previous

rigorous canonical ensemble equilibrium statistical treatment leading to a

quantum theory of the atom laser.

\\ ( http://arXiv.org/abs/cond-mat/0607101 , 171kb)

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Paper: cond-mat/0607102

Date: Wed, 5 Jul 2006 07:51:15 GMT (679kb)

Title: Observing the Formation of Long-range Order during Bose-Einstein

Condensation

Authors: Stephan Ritter, Anton \"Ottl, Tobias Donner, Thomas Bourdel, Michael

K\"ohl, Tilman Esslinger

Comments: 4 pages, 4 figures

Subj-class: Statistical Mechanics

\\

We have experimentally investigated the formation of off-diagonal long-range

order in a gas of ultra-cold atoms. A magnetically trapped atomic cloud

prepared in a highly non-equilibrium state thermalizes and thereby crosses the

Bose-Einstein condensation phase transition. The evolution of phase coherence

between different regions of the sample is constantly monitored and information

on the spatial first-order correlation function is obtained. We observe the

growth of the spatial coherence and the formation of long-range order in

real-time and compare it to the growth of the atomic density. We find that even

after long-range phase coherence has been established, density ordering is

still progressing which is not compatible with the formation of

quasi-condensates but rather suggests a kinetic evolution of the growth

process.

\\ ( http://arXiv.org/abs/cond-mat/0607102 , 679kb)

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Paper: cond-mat/0607103

Date: Wed, 5 Jul 2006 09:08:18 GMT (43kb)

Title: Bose-Condensed Gases in a 1D Optical Lattice at Finite Temperatures

Authors: E. Arahata and T. Nikuni

Comments: Comments: 6 pages, 3 figures, submitted to Quantum Fluids and Solids

Conference (QFS 2006)

Subj-class: Other

\\

We study equilibrium properties of Bose-Condensed gases in a one-dimensional

(1D) optical lattice at finite temperatures. We assume that an additional

harmonic confinement is highly anisotropic, in which the confinement in the

radial directions is much tighter than in the axial direction. We derive a

quasi-1D model of the Gross-Pitaeavkill equation and the Bogoliubov equations,

and numerically solve these equations to obtain the condensate fraction as a

function of the temperature.

\\ ( http://arXiv.org/abs/cond-mat/0607103 , 43kb)

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Paper: cond-mat/0607116

Date: Wed, 5 Jul 2006 13:35:07 GMT (233kb)

Title: Non-equilibrium dynamics of a Bose-Einstein condensate in an optical

lattice

Authors: Kristan Temme and Thomas Gasenzer

Comments: 9 pages RevTeX, 3 figures

Report-no: HD-THEP-06-11

Subj-class: Other

\\

The dynamical evolution of a Bose-Einstein condensate trapped in a

one-dimensional lattice potential is investigated theoretically in the

framework of the Bose-Hubbard model. The emphasis is set on the

far-from-equilibrium evolution in a case where the gas is strongly interacting.

This is realized by an appropriate choice of the parameters in the Hamiltonian,

and by starting with an initial state, where one lattice well contains a

Bose-Einstein condensate while all other wells are empty. Oscillations of the

condensate as well as non-condensate fractions of the gas between the different

sites of the lattice are found to be damped as a consequence of the collisional

interactions between the atoms. Functional integral techniques involving

self-consistently determined mean fields as well as two-point correlation

functions are used to derive the two-particle-irreducible (2PI) effective

action. The action is expanded in inverse powers of the number of field

components N, and the dynamic equations are derived from it to next-to-leading

order in this expansion. This approach reaches considerably beyond the

Hartree-Fock-Bogoliubov mean-field theory, and its results are compared to the

exact quantum dynamics obtained by A.M. Rey et al., Phys. Rev. A 69, 033610

(2004) for small atom numbers.

\\ ( http://arXiv.org/abs/cond-mat/0607116 , 233kb)

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Paper: cond-mat/0607119

Date: Wed, 5 Jul 2006 13:46:50 GMT (40kb)

Title: Mixing-demixing in a trapped degenerate fermion-fermion mixture

Authors: Sadhan K. Adhikari

Comments: 6 pages, 10 figures

Subj-class: Soft Condensed Matter

Journal-ref: Phys. Rev. A 73 (2006) 043619 (1-6)

\\

We use a time-dependent dynamical mean-field-hydrodynamic model to study

mixing-demixing in a degenerate fermion-fermion mixture (DFFM). It is

demonstrated that with the increase of interspecies repulsion and/or trapping

frequencies, a mixed state of DFFM could turn into a fully demixed state in

both three-dimensional spherically-symmetric as well as quasi-one-dimensional

configurations. Such a demixed state of a DFFM could be experimentally realized

by varying an external magnetic field near a fermion-fermion Feshbach

resonance, which will result in an increase of interspecies fermion-fermion

repulsion, and/or by increasing the external trap frequencies.

\\ ( http://arXiv.org/abs/cond-mat/0607119 , 40kb)

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Paper: cond-mat/0607123

Date: Wed, 5 Jul 2006 14:35:31 GMT (418kb)

Title: Adiabatic Phase Diagram on Degenerate Fermi Gas with Feshbach-Resonance

Authors: S. Watabe, T. Nikuni, N. Nygaard, J. E. Williams, C. W. Clark

Comments: 6 pages, 7 figures, submitted to Quantum Fluids and Solids Conference

(QFS 2006)

Subj-class: Other

\\

We determine the adiabatic phase diagrams for a resonantly-coupled system of

Fermi atoms and Bose molecules confined in a harmonic trap by using the local

density approximation. The key idea of our work is conservation of entropy

through the adiabatic process. We also calculate the molecular conversion

efficiency as a function of the initial temperature. Our work helps to

understand recent experiments on the BCS-BEC crossover, in terms of the initial

temperature measured before a sweep of the magnetic field.

\\ ( http://arXiv.org/abs/cond-mat/0607123 , 418kb)

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Paper: cond-mat/0607127

Date: Wed, 5 Jul 2006 16:59:13 GMT (591kb)

Title: Spin Hall effects for cold atoms in a light induced gauge potential

Authors: Shi-Liang Zhu, Hao Fu, C.-J. Wu, S. -C. Zhang, and L. -M. Duan

Comments: 4 pages

Subj-class: Mesoscopic Systems and Quantum Hall Effect

\\

We propose an experimental scheme to observe spin Hall effects with cold

atoms in a light induced gauge potential. Under an appropriate configuration,

the cold atoms moving in a spatially varying laser field experience an

effective spin-dependent gauge potential. Through numerical simulation, we

demonstrate that such a gauge field leads to observable spin Hall currents

under realistic conditions. We also discuss the quantum spin Hall state in an

optical lattice.

\\ ( http://arXiv.org/abs/cond-mat/0607127 , 591kb)

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Paper: cond-mat/0603279

replaced with revised version Wed, 5 Jul 2006 14:43:54 GMT (975kb)

Title: Hybrid apparatus for Bose-Einstein condensation and cavity quantum

electrodynamics: Single atom detection in quantum degenerate gases

Authors: Anton \"{O}ttl, Stephan Ritter, Michael K\"ohl and Tilman Esslinger

Subj-class: Other

Journal-ref: Rev. Sci. Instrum. 77, 063118 (2006)

DOI: 10.1063/1.2216907

\\ ( http://arXiv.org/abs/cond-mat/0603279 , 975kb)

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Paper: quant-ph/0607033

Date: Wed, 5 Jul 2006 09:33:50 GMT (40kb)

Title: Strong light-matter coupling: parametric interactions in a cavity and

free-space

Authors: I. B. Mekhov, V. S. Egorov, V. N. Lebedev, P. V. Moroshkin, I. A.

Chekhonin, S. N. Bagayev

Comments: 4 pages, 2 figures

\\

We consider parametric interactions of laser pulses in a coherent macroscopic

ensemble of resonant atoms, which are possible in the strong coupling regime of

light-matter interaction. The spectrum condensation (lasing at collective

vacuum Rabi sidebands) was studied in an active cavity configuration.

Parametric interactions under the strong light-matter coupling were proved even

in free space. In contrast to bichromatic beats in a cavity, they were shown to

appear due to interference between polaritonic wave packets of different group

velocities.

\\ ( http://arXiv.org/abs/quant-ph/0607033 , 40kb)

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\\

Paper: physics/0607034

Date: Wed, 5 Jul 2006 06:40:29 GMT (199kb)

Title: A Radio-Frequency Atom Chip for Trapping Atoms in Strong-field Seeking

State

Authors: Xiaolin Li, Haichao Zhang, Min Ke, Bo Yan, and Yuzhu Wang

Subj-class: Atomic Physics

\\

Based on dressed-state theory, we propose two kinds of wire configuration

fabricated on an atom chip surface. Two dimensional (2D) adiabatic rf trap can

be created above the atom chip surface with a static bias magnetic field. Atoms

in strong-seeking state can be trapped in the trap by selecting the positive

detuning between frequency of rf magnetic field and resonance frequency of two

Zeeman sublevels. We also discuss optimization of loading efficiency and trap

depth and how to decide proper construction when design an rf atom chip.

\\ ( http://arXiv.org/abs/physics/0607034 , 199kb)

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\\

Paper: physics/0607041

Date: Wed, 5 Jul 2006 12:09:30 GMT (72kb)

Title: Mechanical effect of van der Waals interactions observed in real time in

an ultracold Rydberg gas

Authors: T. Amthor and M. Reetz-Lamour and S. Westermann and J. Denskat, and M.

Weidem\"uller

Subj-class: Atomic Physics

\\

We present time-resolved spectroscopic measurements of Rydberg-Rydberg

interactions in an ultracold gas, revealing the pair dynamics induced by

long-range van der Waals interactions between the atoms. By detuning the

excitation laser, a specific pair distribution is prepared. Penning ionization

on a microsecond timescale serves as a probe for the pair dynamics under the

influence of the attractive long-range forces. Comparison with a Monte Carlo

model not only explains all spectroscopic features but also gives quantitative

information about the interaction potentials. The results imply that the

interaction-induced ionization rate can be influenced by the excitation laser.

Surprisingly, interaction-induced ionization is also observed for Rydberg

states with purely repulsive interactions.

\\ ( http://arXiv.org/abs/physics/0607041 , 72kb)

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\\

Paper: cond-mat/0607138

Date: Thu, 6 Jul 2006 12:26:33 GMT (186kb)

Title: Color superfluidity and "baryon" formation in ultracold fermions

Authors: Akos Rapp, Gergely Zarand, Carsten Honerkamp, Walter Hofstetter

Comments: 5 PRL pages, 2 figures

Subj-class: Strongly Correlated Electrons; Superconductivity

\\

We study optical lattices loaded with fermionic atoms in three different

internal quantum states (colors) alpha = 1..3, which are interacting through an

attractive interaction, U<0. Within a nonperturbative variational calculation

we show that for equal color densities n_1=n_2=n_3 and small coupling, |U| <

|U_C|, a color superfluid state emerges with a vector-like order parameter and

a tendency to domain formation. For |U| > |U_C|, on the other hand, a trionic

phase appears where triplets of atoms with different color form single fermions

(trions). These two phases are the analogues of the color superconducting and

baryonic phases in QCD. In ultracold fermions, the transition between them is

found to be second order rather than first order due to the short-range

interaction. Our results demonstrate that quantum simulations with ultracold

gases will be able to shed light on outstanding problems in quantum field

theory.

\\ ( http://arXiv.org/abs/cond-mat/0607138 , 186kb)

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\\

Paper: cond-mat/0607147

Date: Thu, 6 Jul 2006 06:40:10 GMT (516kb)

Title: Vortex Core Structure in Neutral Fermion Superfluids with Population

Imbalance

Authors: M. Takahashi, T. Mizushima, M. Ichioka, K. Machida

Comments: 5 pages, 5 figures

Subj-class: Superconductivity

\\

Quantized vortex core structure is theoretically investigated in Fermion

superfluids with population imbalance for two atom species of neutral atom

clouds near a Feshbach resonance. In contrast with vortex core in balance case

where the quantum depletion makes a vortex visible through the density profile

measurement, the vortex core is filled in and becomes less visible because the

quantized discrete bound states are occupied exclusively by the majority

species. Yet it is shown that the core can be visible through the minority

density profile experiment using phase contrast imaging, revealing an

interesting opportunity to examine low-lying Fermionic core bound states

unexplored so far.

\\ ( http://arXiv.org/abs/cond-mat/0607147 , 516kb)

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\\

Paper: cond-mat/0607160

Date: Thu, 6 Jul 2006 16:10:29 GMT (60kb)

Title: Stability and excitations of solitons in 2D Bose-Einstein condensates

Authors: S. Tsuchiya, F. Dalfovo, C. Tozzo, and L. Pitaevskii

Comments: 6 pages, 2 figures

Subj-class: Other

\\

The small oscillations of solitons in 2D Bose-Einstein condensates are

investigated by solving the Kadomtsev-Petviashvili equation which is valid when

the velocity of the soliton approaches the speed of sound. We show that the

soliton is stable and that the lowest excited states obey the same dispersion

law as the one of the stable branch of excitations of a 1D gray soliton in a 2D

condensate. The role of these states in thermodynamics is discussed.

\\ ( http://arXiv.org/abs/cond-mat/0607160 , 60kb)

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\\

Paper: cond-mat/0607166

Date: Thu, 6 Jul 2006 15:26:18 GMT (373kb)

Title: Vortex Lattice Structures of a Bose-Einstein Condensate in a Rotating

Lattice Potential

Authors: T. Sato, T. Ishiyama and T. Nikuni

Comments: 6 pages, 8 figures, submitted to Quantum Fluids and Solids Conference

(QFS 2006)

Subj-class: Other

\\

We study vortex lattice structures of a trapped Bose-Einstein condensate in a

rotating lattice potential by numerically solving the time-dependent

Gross-Pitaevskii equation. By rotating the lattice potential, we observe the

transition from the Abrikosov vortex lattice to the pinned lattice. We

investigate the transition of the vortex lattice structure by changing

conditions such as angular velocity, intensity, and lattice constant of the

rotating lattice potential.

\\ ( http://arXiv.org/abs/cond-mat/0607166 , 374kb)

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\\

Paper: cond-mat/0607169

Date: Thu, 6 Jul 2006 15:47:55 GMT (65kb)

Title: Black soliton in a quasi-one-dimensional trapped fermion-fermion mixture

Authors: Sadhan K. Adhikari

Comments: 7 pages, 10 figures

Subj-class: Soft Condensed Matter

\\

Employing a time-dependent mean-field-hydrodynamic model we study the

generation of black solitons in a degenerate fermion-fermion mixture in a

cigar-shaped geometry using variational and numerical solutions. The black

soliton is found to be the first stationary vibrational excitation of the

system and is considered to be a nonlinear continuation of the vibrational

excitation of the harmonic oscillator state. We illustrate the stationary

nature of the black soliton, by studying different perturbations on it after

its formation.

\\ ( http://arXiv.org/abs/cond-mat/0607169 , 65kb)

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\\

Paper: cond-mat/0607170

Date: Thu, 6 Jul 2006 16:17:28 GMT (780kb)

Title: Atom counting in ultra-cold gases using photoionisation and ion

detection

Authors: T. Campey, C. J. Vale, M. J. Davis, S. Kraft, C. Zimmermann, J.

Fort\'{a}gh, N. R. Heckenberg, H. Rubinsztein-Dunlop

Comments: 10 pages, 6 figures

Subj-class: Other

\\

We analyse photoionisation and ion detection as a means of accurately

counting ultra-cold atoms. We show that it is possible to count clouds

containing many thousands of atoms with accuracies better than $N^{-1/2}$ with

current technology. This allows the direct probing of sub-Poissonian number

statistics of atomic samples. The scheme can also be used for efficient single

atom detection with high spatio-temporal resolution. All aspects of a realistic

detection scheme are considered, and we discuss experimental situations in

which such a scheme could be implemented.

\\ ( http://arXiv.org/abs/cond-mat/0607170 , 780kb)

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\\

Paper: cond-mat/0607172

Date: Thu, 6 Jul 2006 18:58:44 GMT (426kb)

Title: Time interval distributions of atoms in atomic beams

Authors: Michael K\"ohl, Anton \"Ottl, Stephan Ritter, Tobias Donner, Thomas

Bourdel, Tilman Esslinger

Comments: 4 pages, 3 figures

Subj-class: Statistical Mechanics

\\

We report on the experimental investigation of two-particle correlations

between neutral atoms in a Hanbury Brown and Twiss experiment. Both an atom

laser beam and a pseudo-thermal atomic beam are extracted from a Bose-Einstein

condensate and the atom flux is measured with a single atom counter. We

determine the conditional and the unconditional detection probabilities for the

atoms in the beam and find good agreement with the theoretical predictions.

\\ ( http://arXiv.org/abs/cond-mat/0607172 , 426kb)

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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/ ========================================================================= 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 Mon Jul 10 2006 - 09:35:38 EST

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