# Matt's arXiv selection, Monday 10th July 2006.

From: Matthew Davis <mdavis_at_physics.uq.edu.au>
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
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}
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
\\
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
\\
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
\\ ( 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
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
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
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
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
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
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
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
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
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
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
\\
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
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
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
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
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
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
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/
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Received on Mon Jul 10 2006 - 09:35:38 EST

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