# Matt's arXiv selection: week ending 3 April 2009

From: Matthew Davis <mdavis_at_physics.uq.edu.au>
Date: Mon, 25 May 2009 08:41:19 +1000

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

Dear subscribers,

We again have Andy Ferris to thank for this week's update. There are 32 new
preprints and 14 replacements in this mailing.

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arXiv:0903.4713
Date: Thu, 26 Mar 2009 22:33:06 GMT (11kb)

Title: Effect of random on-site energies on the critical temperature of a
lattice Bose gas
Authors: Luca Dell'Anna, Stefano Fantoni, Pasquale Sodano, Andrea Trombettoni
Categories: cond-mat.stat-mech cond-mat.dis-nn
Comments: To appear in Laser Physics, issue on the LPHYS'08 conference
(Trondheim, 2008)
\\
We study the effect of random on-site energies on the critical temperature of
a non-interacting Bose gas on a lattice. In our derivation the on-site energies
are distributed according a Gaussian probability distribution function having
vanishing average and variance $v_o2$. By using the replicated action obtained
by averaging on the disorder, we perform a perturbative expansion for the Green
functions of the disordered system. We evaluate the shift of the chemical
potential induced by the disorder and we compute, for $v_o2 << 1$, the
critical temperature for condensation. We find that, for large filling,
disorder slightly enhances the critical temperature for condensation.
\\ ( http://arxiv.org/abs/0903.4713 , 11kb)
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arXiv:0903.4732
Date: Fri, 27 Mar 2009 05:31:16 GMT (577kb)

Title: Creation of Dirac monopoles in spinor Bose-Einstein condensates
Authors: Ville Pietil\"a and Mikko M\"ott\"onen
Categories: cond-mat.other
Comments: 5 pages + 4 pages of supplementary material
\\
We demonstrate theoretically that using standard external magnetic fields,
one can imprint point-like topological defects to the spin texture of a dilute
Bose-Einstein condensate. Symmetries of the condensate order parameter render
this topological defect to be accompanied with a vortex filament corresponding
to the Dirac string of a magnetic monopole. The vorticity in the condensate
coincides with the magnetic field of a magnetic monopole, providing an ideal
analogue to the monopole studied by Dirac.
\\ ( http://arxiv.org/abs/0903.4732 , 577kb)
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arXiv:0903.4784
Date: Fri, 27 Mar 2009 12:19:31 GMT (31kb)

Title: Suppression of selection among broken-symmetry states by
cross-correlated noises in double-well system
Authors: Iurii V. Gudyma, Artur Iu. Maksymov
Categories: cond-mat.stat-mech
\\
Suppression of selection among broken-symmetry states has been found in
double-well system resulting from two simultaneous correlated white noises, one
additive and the other multiplicative. Symmetry-asymmetry-symmetry transition
is re-entrant as a function of the additive noise intensity for small
multiplicative noise.
\\ ( http://arxiv.org/abs/0903.4784 , 31kb)
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arXiv:0903.4823
Date: Fri, 27 Mar 2009 17:51:53 GMT (1551kb)

Title: Quantum transport through a Tonks-Girardeau gas
Authors: Stefan Palzer, Christoph Zipkes, Carlo Sias, and Michael K\"ohl
Categories: cond-mat.mes-hall
\\
We investigate the propagation of spin impurity atoms through a strongly
interacting one-dimensional Bose gas. The initially well localized impurities
are accelerated by a constant force, very much analogous to electrons subject
to a bias voltage, and propagate as a one-dimensional guided atom laser pulse.
We follow the motion of the impurities in situ and characterize the interaction
induced dynamics. We observe a very complex non-equilibrium dynamics, including
the emergence of large density fluctuations in the remaining Bose gas, and
multiple scattering events leading to dissipation of the impurity's motion.
\\ ( http://arxiv.org/abs/0903.4823 , 1551kb)
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arXiv:0903.4837
Date: Fri, 27 Mar 2009 16:06:51 GMT (1233kb,D)

Title: Experimental demonstration of single-site addressability in a
two-dimensional optical lattice
Authors: Peter W\"urtz, Tim Langen, Tatjana Gericke, Andreas Koglbauer, Herwig
Ott
Categories: cond-mat.other
\\
We demonstrate single site addressability in a two-dimensional optical
in the lattice potential we use a focused electron beam to remove atoms from
selected sites. The patterned structure is subsequently imaged by means of
scanning electron microscopy. This technique allows us to create arbitrary
patterns of mesoscopic atomic ensembles. We find that the patterns are
remarkably stable against tunneling diffusion. Such micro-engineered quantum
gases are a versatile resource for applications in quantum simulation, quantum
optics and quantum information processing with neutral atoms.
\\ ( http://arxiv.org/abs/0903.4837 , 1233kb)
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arXiv:0903.4858
Date: Fri, 27 Mar 2009 17:26:13 GMT (452kb)

Title: Feshbach Resonances and Medium Effects in ultracold atomic Gases
Authors: G. M. Bruun
Categories: cond-mat.other
Comments: Presented at the 5th workshop on Critical Stability, Erice, Italy
13-17 October 2008. 8 pages, 3 figures
DOI: 10.1007/s00601-009-0040-9
\\
We develop an effective low energy theory for multi-channel scattering of
cold atomic alkali atoms with particular focus on Feshbach resonances. The
scattering matrix is expressed in terms of observables only and the theory
allows for the inclusion of many-body effects both in the open and in the
closed channels.
We then consider the frequency and damping of collective modes for Fermi
gases and demonstrate how medium effects significantly increase the scattering
rate determining the nature of the modes. Our results obtained with no fitting
parameters are shown to compare well with experimental data.
\\ ( http://arxiv.org/abs/0903.4858 , 452kb)
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arXiv:0903.4859
Date: Fri, 27 Mar 2009 17:27:21 GMT (145kb)

Title: Controlling Grey Solitons in a Trap
Authors: Ayan Khan, Rajneesh Atre and Prasanta K. Panigrahi
Categories: cond-mat.other
\\
It is pointed out that, the energy and velocity profiles of the recently
observed grey solitons match well with the Lieb mode of the Gross-Pitaevskii
equation. These nonlinear excitations are found to have strong coupling with
the trap at low momenta and hence can be effectively isolated from the
Bogoliubov sound modes, which responds weakly to harmonic confinement. This
strong coupling with the trap also makes the grey soliton amenable for control
and manipulation through both trap modulation and temporal variation of the two
body interaction.
\\ ( http://arxiv.org/abs/0903.4859 , 145kb)
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arXiv:0903.5016
Date: Sun, 29 Mar 2009 01:20:41 GMT (408kb)

Title: Pulsating and persistent vector solitons in a Bose-Einstein condensate
in a lattice upon phase separation instability
Authors: Uttam Shrestha, Juha Javanainen, and Janne Ruostekoski
Categories: cond-mat.other
\\
We study numerically the outcome of the phase separation instability of a
dual-species Bose-Einstein condensate in an optical lattice. When only one
excitation mode is unstable a bound pair of a bright and dark solitons
periodically appears and disappears, whereas for more than one unstable mode a
persistent soliton-antisoliton pair develops.
\\ ( http://arxiv.org/abs/0903.5016 , 408kb)
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arXiv:0903.5153
Date: Mon, 30 Mar 2009 08:57:38 GMT (46kb)

Title: Critical behavior and scaling in trapped systems
Authors: Massimo Campostrini and Ettore Vicari
Categories: cond-mat.stat-mech
\\
We study the scaling properties of critical particle systems confined by a
potential. Using renormalization-group arguments, we show that their critical
behavior can be cast in the form of a trap-size scaling, resembling finite-size
scaling theory, with a nontrivial trap critical exponent theta, which describes
how the correlation length scales with the trap size l, i.e., $\xi\sim l^\theta$ at the critical point. theta depends on the universality class of the
transition, the power law of the confining potential, and on the way it is
coupled to the critical modes. We present numerical results for two-dimensional
lattice gas (Ising) models with various types of harmonic traps, which support
the trap-size scaling scenario.
\\ ( http://arxiv.org/abs/0903.5153 , 46kb)
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arXiv:0903.5226
Date: Mon, 30 Mar 2009 14:05:13 GMT (38kb)

Title: Fermion mediated long-range interactions of bosons in the 1D
Bose-Fermi-Hubbard model
Authors: Alexander Mering, Michael Fleischhauer
Categories: cond-mat.other cond-mat.str-el
\\
The ground-state phase diagram of mixtures of spin polarized fermions and
bosons in a 1D periodic lattice is discussed in the limit of large fermion
hopping. Formally eliminating the fermions gives rise to a long-range
oscillatory interaction between bosons, which is the origin of charge density
waves (CDW). We derive a renormalized effective Hamiltonian for half filling of
fermions that allows an analytic description of the transition from the
insulating Mott-insulator (MI) and CDW phases to a superfluid (SF) phase for
bosons. For non-commensurate boson filling a spatial phase separation (PS)
between incompressible Mott and CDW regions occurs for small hopping
amplitudes. The phase diagram is calculated from the effective model, in
particular the CDW--SF transition is discussed. The analytic predictions agree
well with numerical simulations obtained with the density-matrix
renormalization group. Numerical evidence is given that CDW and SF are
separated by a region with exponentially decaying first-order correlations,
i.e. there is no supersolid phase.
\\ ( http://arxiv.org/abs/0903.5226 , 38kb)
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arXiv:0903.5265
Date: Mon, 30 Mar 2009 17:05:16 GMT (723kb)

Title: Antiferromagnetic Order of Repulsively Interacting Fermions on Optical
lattices
Authors: Tobias Gottwald, Peter van Dongen
Categories: cond-mat.quant-gas
\\
The N\'eel state in fermionic mixtures of two pseudospin species in an
optical lattice is analyzed at low temperatures. Experimentally it remains a
challenge to demonstrate antiferromagnetic correlations in ultracold fermionic
quantum gases. We find that, while in balanced systems the N\'eel order
parameter can point in any spatial direction, in imbalanced mixtures
antiferromagnetism is strictly perpendicular to the quantization axis (i.e.,
the z-axis). Since, experimentally, one always has to assume some minimal
imbalance this should have important consequences for ongoing experiments.
\\ ( http://arxiv.org/abs/0903.5265 , 723kb)
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arXiv:0903.5019
Date: Sun, 29 Mar 2009 03:38:16 GMT (91kb)

Title: Nonlinear Phenomenology from Quantum Mechanics: Soliton in a Lattice
Authors: Juha Javanainen and Uttam Shrestha
Categories: quant-ph
Journal-ref: Phys. Rev. Lett. 101, 170405 (2008)
\\
We study a soliton in an optical lattice holding bosonic atoms quantum
mechanically using both an exact numerical solution and quantum Monte Carlo
simulations. The computation of the state is combined with an explicit account
of the measurements of the numbers of the atoms at the lattice sites. In
particular, importance sampling in the quantum Monte Carlo method arguably
produces faithful simulations of individual experiments. Even though the
quantum state is invariant under lattice translations, an experiment may show a
noisy version of the localized classical soliton.
\\ ( http://arxiv.org/abs/0903.5019 , 91kb)
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arXiv:0903.5181
Date: Mon, 30 Mar 2009 11:08:32 GMT (27kb)

Title: Numerical and Analytical Approach to the Quantum Dynamics of Two Coupled
Spins in Bosonic Baths
Authors: Alessandro Sergi, Ilya Sinayskiy, Francesco Petruccione
Categories: quant-ph
\\
The quantum dynamics of a spin chain interacting with multiple bosonic baths
is described in a mixed Wigner-Heisenberg representation. The formalism is
illustrated by simulating the time evolution of the reduced density matrix of
two coupled spins, where each spin is also coupled to its own bath of harmonic
oscillators. In order to prove the validity of the approach, an analytical
solution in the Born-Markov approximation is found. The agreement between the
two methods is shown.
\\ ( http://arxiv.org/abs/0903.5181 , 27kb)
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arXiv:0903.5029
Date: Sun, 29 Mar 2009 08:46:01 GMT (744kb)

Title: Time-of-Flight Signatures of Bosons in a Double Well
Authors: Analabha Roy, Linda E. Reichl
Categories: physics.atom-ph
\\
We present analytical and numerical treatments for evaluating the
time-of-flight momentum distribution for the stationary states of a two-boson
system trapped in a quartic double-well potential, paying particular attention
to the Tonks and noninteracting regimes. We find that the time-of-flight
distributions can serve as a valuable tool in profiling the states of this
system, which will be useful in understanding the chaotic dynamics of coherent
quantum controlled excitations of trapped bosons.
\\ ( http://arxiv.org/abs/0903.5029 , 744kb)
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arXiv:0903.5324
Date: Tue, 31 Mar 2009 00:02:19 GMT (25kb)

Title: Evaporative depolarization and spin transport in an ultracold trapped
Fermi gas
Authors: Meera M. Parish and David A. Huse
Categories: cond-mat.quant-gas
\\
We consider a partially spin-polarized atomic Fermi gas in a
high-aspect-ratio trap, with a flux of predominantly spin-up atoms exiting the
center of the trap. We argue that such a scenario can be produced by
evaporative cooling, and we find that it can result in a substantially
non-equilibrium polarization pattern for typical experimental parameters. We
offer this as a possible explanation for the quantitative discrepancies in
recent experiments on spin-imbalanced unitary Fermi gases.
\\ ( http://arxiv.org/abs/0903.5324 , 25kb)
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arXiv:0903.5343
Date: Tue, 31 Mar 2009 15:40:09 GMT (317kb)

Title: Repulsive Fermi gas in a harmonic trap: Ferromagnetism and spin textures
Authors: L. J. LeBlanc, J. H. Thywissen, A. A. Burkov, A. Paramekanti
Categories: cond-mat.quant-gas
\\
We study ferromagnetism in a repulsively interacting two-component Fermi gas
in a harmonic trap at zero net magnetization. Within a local density
approximation, the two components phase-separate beyond a critical interaction
strength, with one species having a higher density at the trap center. The mean
field release energy depends on the interaction strength and contains a sharp
signature of this transition. To go beyond the local density approximation, we
derive an energy functional which includes a term that depends on the local
magnetization gradient and acts as a surface tension'. Using this energy
functional, we numerically study the energetics of some candidate spin textures
which may be stabilized in a harmonic trapping potential. We find that a
hedgehog state has a lower energy than an in-out' domain wall state in an
isotropic trap. Upon inclusion of trap anisotropy we find that the hedgehog
magnetization profile gets distorted due to the surface tension term, this
distortion being more apparent for small atom numbers. We estimate that the
magnetic dipole interaction does not play a significant role in this system. We
consider implications for experiments on trapped two-component Fermi systems
such as Li-6 and K-40 gases.
\\ ( http://arxiv.org/abs/0903.5343 , 317kb)
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arXiv:0903.5366
Date: Tue, 31 Mar 2009 04:59:32 GMT (843kb)

Title: Virial expansion for a strongly correlated Fermi gas
Authors: Xia-Ji Liu, Hui Hu and Peter D. Drummond
Categories: cond-mat.quant-gas cond-mat.stat-mech
\\
Using a high temperature virial expansion, we present a controllable study of
the thermodynamics of strongly correlated Fermi gases near the BEC-BCS
crossover region. We propose a practical way to determine the expansion
coefficients for both harmonically trapped and homogeneous cases, and calculate
the third order coefficient $b_{3}(T)$ at finite temperatures $T$. At
resonance, a $T$-independent coefficient
$b_{3,\infty}^{\hom}\approx-0.29095295$ is determined in free space. These
results are compared with a recent thermodynamic measurement of $^{6}$Li atoms,
at temperatures below the degeneracy temperature, and with Monte Carlo
simulations.
\\ ( http://arxiv.org/abs/0903.5366 , 843kb)
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arXiv:0903.5371
Date: Tue, 31 Mar 2009 05:46:16 GMT (883kb)

Title: Ultracold Atomic Gases: Novel States of Matter
Authors: L. Mathey, S.-W. Tsai, and A. H. Castro Neto
Categories: cond-mat.quant-gas cond-mat.other
Comments: 43 pages, 17 figures. To appear in the Encyclopedia of Complexity and
Systems Science, Dr. R. A. Meyers (Ed.) (Springer Heidelberg, 2009)
\\
Article to appear in the Encyclopedia of Complexity and Systems Science, Dr.
R. A. Meyers (Ed.) (Springer Heidelberg, 2009).
\\ ( http://arxiv.org/abs/0903.5371 , 883kb)
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arXiv:0903.5459
Date: Tue, 31 Mar 2009 13:25:37 GMT (605kb)

Title: Nonequilibrium Josephson oscillations in Bose-Einstein condensates
without dissipation
Authors: Mauricio Trujillo Martinez, Anna Posazhennikova, and Johann Kroha
Categories: cond-mat.quant-gas cond-mat.other
\\
We discuss a problem of a nonadiabatic Bose Josephson junction. We use
non-equilibrium field theoretical methods to account for excitations above the
condensates, which are induced by the nonadibaticity. We show how the coherent
tunneling between the condensates, known from mean-field calculations, gets
drastically modified by the non-equilibrium effects. We also estimate a
time-scale, at which the condensate dynamics switches from slow Josephson
oscillations to fast Rabi oscillations between the descrete quasi-particle
levels. We analyze in detail how this time scale depends on the parameters of
our system.
\\ ( http://arxiv.org/abs/0903.5459 , 605kb)
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arXiv:0903.5190
Date: Mon, 30 Mar 2009 11:42:31 GMT (832kb)

Title: Threshold of a random laser based on Raman gain in cold atoms
Authors: William Guerin (INLN), Nicolas Mercadier (INLN), Davide Brivio (INLN),
Robin Kaiser (INLN)
Categories: physics.optics cond-mat.dis-nn physics.atom-ph
\\
We address the problem of achieving a random laser with a cloud of cold
atoms, in which gain and scattering are provided by the same atoms. In this
system, the elastic scattering cross-section is related to the complex atomic
polarizability. As a consequence, the random laser threshold is expressed as a
function of this polarizability, which can be fully determined by spectroscopic
measurements. We apply this idea to experimentally evaluate the threshold of a
random laser based on Raman gain between non-degenerate Zeeman states and find
a critical optical thickness on the order of 200, which is within reach of
state-of-the-art cold-atom experiments.
\\ ( http://arxiv.org/abs/0903.5190 , 832kb)
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arXiv:0904.0050
Date: Wed, 1 Apr 2009 02:29:36 GMT (29kb,D)

Title: Rigorous Upper Bound on the Critical Temperature of Dilute Bose Gases
Authors: Robert Seiringer, Daniel Ueltschi
Categories: cond-mat.stat-mech cond-mat.quant-gas
\\
We prove exponential decay of the off-diagonal correlation function in the
two-dimensional homogeneous Bose gas when a2 \rho is small and the temperature
T satisfies T > 4 \pi \rho / \ln |\ln(a2\rho). Here, a is the scattering
length of the repulsive interaction potential and \rho is the density. To
leading order in a2 \rho, this bound agrees with the expected critical
temperature for superfluidity. In the three-dimensional Bose gas, exponential
decay is proved when \Delta T_c / T_c0 > 5 \sqrt{a \rho^{1/3}}, where T_c0 is
the critical temperature of the ideal gas. While this condition is not expected
to be sharp, it gives a rigorous upper bound on the critical temperature for
Bose-Einstein condensation.
\\ ( http://arxiv.org/abs/0904.0050 , 29kb)
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arXiv:0904.0053
Date: Wed, 1 Apr 2009 10:18:46 GMT (169kb)

Title: Comparative study of the finite-temperature thermodynamics of a unitary
Fermi gas
Authors: Fang Qin, Ji-sheng Chen
Categories: cond-mat.quant-gas cond-mat.other
Comments: 7 pages; accepted for publication in Phys. Rev. A
\\
We study the finite-temperature thermodynamics of a unitary Fermi gas. The
chemical potential, energy density and entropy are given analytically with the
quasi-linear approximation. The ground state energy agrees with previous
theoretical and experimental results. Recently, the generalized exclusion
statistics is applied to the discussion of the finite-temperature unitary Fermi
gas thermodynamics. A concrete comparison between the two different approaches
is performed. Emphasis is made on the behavior of the entropy per particle. In
physics, the slope of entropy gives the information for the effective fermion
mass $m^*/m$ in the low temperature strong degenerate region. Compared with
$m^*/m \approx 0.70<1$ given in terms of the generalized exclusion statistics,
our quasi-linear approximation determines $m^*/m\approx 1.11>1$.
\\ ( http://arxiv.org/abs/0904.0053 , 169kb)
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arXiv:0904.0086
Date: Wed, 1 Apr 2009 08:16:52 GMT (860kb)

Title: Excited spin states and phase separation in spinor Bose-Einstein
condensates
Authors: Michal Matuszewski, Tristram J. Alexander, Yuri S. Kivshar
Categories: cond-mat.quant-gas cond-mat.other
\\
We analyze the structure of spin-1 Bose-Einstein condensates in the presence
of a homogenous magnetic field. We classify the homogenous stationary states
and study their existence, bifurcations, and energy spectra. We reveal that the
phase separation can occur in the ground state of polar condensates, while the
spin components of the ferromagnetic condensates are always miscible and no
phase separation occurs. Our theoretical model, confirmed by numerical
simulations, explains that this phenomenon takes place when the energy of the
lowest homogenous state is a concave function of the magnetization. In
particular, we predict that phase separation can be observed in a $^{23}$Na
condensate confined in a highly elongated harmonic trap. Finally, we discuss
the phenomena of dynamical instability and spin domain formation.
\\ ( http://arxiv.org/abs/0904.0086 , 860kb)
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arXiv:0904.0155
Date: Wed, 1 Apr 2009 13:24:03 GMT (1778kb)

Title: Effect of interactions on the diffusive expansion of a Bose-Einstein
condensate in a 3D random potential
Authors: N. Cherroret and S. E. Skipetrov
Categories: cond-mat.quant-gas cond-mat.dis-nn
\\
We theoretically study the influence of weak interactions on the diffusive
expansion of a Bose-Einstein condensate in a three-dimensional random
potential. For this purpose we develop a perturbative approach and calculate
analytically the first-order nonlinear correction to the ensemble-averaged
atomic density as a function of position and time. We find that interactions
renormalize the typical diffusion coefficient of the condensate. The magnitude
of the nonlinear correction is controlled by a single dimensionless parameter
that includes both interaction and disorder strengths.
\\ ( http://arxiv.org/abs/0904.0155 , 1778kb)
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arXiv:0807.1945 (*cross-listing*)
Date: Sat, 12 Jul 2008 00:49:29 GMT (485kb,D)
Date (revised v2): Fri, 6 Mar 2009 23:34:41 GMT (459kb,D)
Date (revised v3): Fri, 27 Mar 2009 21:36:45 GMT (459kb,D)

Title: Dynamics of Quantum Vorticity in a Random Potential
Categories: astro-ph cond-mat.quant-gas
Comments: Physical Review Letters, final version
\\
I study the dynamics of a superfluid vortex in a random potential, as in the
inner crust of a neutron star. Below a critical flow velocity of the ambient
superfluid, a vortex is effectively immobilized by lattice forces even in the
limit of zero dissipation. Low-velocity, translatory motion is not dynamically
possible, a result with important implications for understanding neutron star
precession and the dynamical properties of superfluid nuclear matter.
\\ ( http://arxiv.org/abs/0807.1945 , 459kb)
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arXiv:0904.0115
Date: Wed, 1 Apr 2009 09:59:09 GMT (49kb)

Title: Dynamics of an inhomogeneous quantum phase transition
Authors: Jacek Dziarmaga and Marek M. Rams
Categories: quant-ph
\\
We argue that in a second order quantum phase transition driven by an
inhomogeneous quench density of quasiparticle excitations is dramatically
suppressed when velocity at which a critical point propagates across a system
falls below a threshold velocity given by a ratio of the Kibble-Zurek
correlation length to the inverse energy gap at freeze-out. We support this
general prediction by an analytic solution in the particular case of the
quantum Ising chain.
\\ ( http://arxiv.org/abs/0904.0115 , 49kb)
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arXiv:0904.0150
Date: Wed, 1 Apr 2009 13:51:58 GMT (12kb)

Title: Hidden symmetry and nonlinear paraxial atom optics
Authors: F. Impens
Categories: quant-ph
Comments: 5 pages. Submitted to Phys. Rev. A
\\
We exploit a hidden symmetry of the nonlinear wave equation to analyse the
propagation of paraxial and uniform atom-laser beams in time-independent,
quadratic and cylindrical potentials varying smoothly along the propagation
axis. The quality factor and the paraxial ABCD formalism are generalized to
account exactly for mean-field interaction effects in such beams.
\\ ( http://arxiv.org/abs/0904.0150 , 12kb)
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arXiv:0904.0234
Date: Wed, 1 Apr 2009 18:25:35 GMT (34kb)

Title: The impact of magnetic properties on atom-wall interaction
Authors: G. Bimonte, G. L. Klimchitskaya, and V. M. Mostepanenko
Categories: quant-ph
Comments: 14 pages, 2 figures; accepted for publication in Phys. Rev. A
\\
The Lifshitz-type formulas for the free energy and Casimir-Polder force
acting between an atom possessing a permanent magnetic moment and a wall made
of different materials are derived. Simple model allowing analytic results is
considered where the atomic magnetic susceptibility is frequency-independent
and wall is made of ideal metal. Numerical computations of the Casimir-Polder
force are performed for H atom interacting with walls made of ideal metal,
nonmagnetic (Au) and ferromagnetic (Fe) metals and of ferromagnetic dielectric.
It is shown that for the first three wall materials the inclusion of the
magnetic moment of an atom decreases and for the fourth material increases the
magnitude of the Casimir-Polder force.
\\ ( http://arxiv.org/abs/0904.0234 , 34kb)
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arXiv:0904.0238
Date: Wed, 1 Apr 2009 19:32:16 GMT (86kb)

Title: Bragg spectroscopy for measuring Casimir-Polder interactions with
Bose-Einstein condensates above corrugated surfaces
Authors: Gustavo A. Moreno, Diego A. R. Dalvit, Esteban Calzetta
Categories: quant-ph
\\
We propose a method to probe dispersive atom-surface interactions by
measuring via two-photon Bragg spectroscopy the dynamic structure factor of a
Bose-Einstein condensate above corrugated surfaces. We show that this method
enables high resolution measurements of Casimir-Polder forces with present-day
technology.
\\ ( http://arxiv.org/abs/0904.0238 , 86kb)
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arXiv:0904.0225
Date: Wed, 1 Apr 2009 17:24:02 GMT (2968kb)

Title: Demonstrating coherent control in 85Rb2 using ultrafast laser pulses: a
theoretical outline of two experiments
Authors: Hugo E. L. Martay, David J. McCabe, Duncan G. England, Melissa E.
Friedman, Jovana Petrovic, and Ian A. Walmsley
Categories: physics.atom-ph physics.chem-ph
Comments: 8 pages, 9 figures, submitted to PRA
\\
Calculations relating to two experiments that demonstrate coherent control of
preformed rubidium-85 molecules in a magneto-optical trap using ultrafast laser
pulses are presented. In the first experiment, it is shown that pre-associated
molecules in an incoherent mixture of states can be made to oscillate
coherently using a single ultrafast pulse. A novel mechanism that can transfer
molecular population to more deeply bound vibrational levels is used in the
second. Optimal parameters of the control pulse are presented for the
application of the mechanism to molecules in a magneto-optical trap. The
calculations make use of an experimental determination of the initial state of
molecules photoassociated by the trapping lasers in the magneto-optical trap
and use shaped pulses consistent with a standard ultrafast laser system.
\\ ( http://arxiv.org/abs/0904.0225 , 2968kb)
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arXiv:0904.0244 (*cross-listing*)
Date: Wed, 1 Apr 2009 19:23:15 GMT (239kb,D)

Title: A pump-probe study of the photoassociation of rubidium molecules
Authors: David J. McCabe, Duncan G. England, Hugo E. L. Martay, Melissa E.
Friedman, Jovana Petrovic, Emiliya Dimova, B\'eatrice Chatel and Ian A.
Walmsley
Categories: physics.chem-ph physics.atom-ph physics.optics
\\
An experimental pump-probe study of the excited-state dynamics of ultracold
rubidium molecules is presented together with numerical simulations of the
process. The formation of loosely bound excited-state dimers by
photoassociation is observed as a first step towards a fully coherent pump-dump
approach to the stabilization of Rb$_2$ into its lowest ground vibrational
states. A spectroscopic study of the initial state of the colliding atom pairs
prior to the photoassociation process is performed.
\\ ( http://arxiv.org/abs/0904.0244 , 239kb)
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arXiv:0904.0412
Date: Thu, 2 Apr 2009 16:00:21 GMT (1120kb,D)

Title: Probing interaction-induced ferromagnetism in optical superlattices
Authors: J. von Stecher, E. Demler, M. D. Lukin, A. M. Rey
Categories: cond-mat.quant-gas
\\
We propose a controllable method for observing interaction induced
ferromagnetism in ultracold fermionic atoms loaded in optical superlattices. We
first discuss how to probe and control Nagaoka ferromagnetism in an array of
isolated plaquettes (four lattice sites arranged in a square). Next, we show
that introducing a weak interplaquette coupling destroys the ferromagnetic
correlations. To overcome this instability we propose to mediate long-range
ferromagnetic correlations among the plaquettes via double-exchange processes.
Conditions for experimental realization and techniques to detect such states
are discussed.
\\ ( http://arxiv.org/abs/0904.0412 , 1120kb)
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The replacements:

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\\
arXiv:cond-mat/0607433
replaced with revised version Sun, 29 Mar 2009 23:01:20 GMT (175kb,D)

Title: Coherent Collective Excitations in a Superfluid: Spontaneously Broken
Symmetries and Fluctuations-Dissipation
Authors: S.J. Han
Categories: cond-mat.other
Comments: 84 pages, 1 figure, (1) The Bose-Einstein condensation is discussed
in both a degenerate Bose gas and an imperfect Bose gas to show how the
pair-interaction affects the nature of phase-transition, (2) The
Onsager-Feynman quantization of circulation in He II is discussed with the
identifiable cause with Planck's quantum condition
\\ ( http://arxiv.org/abs/cond-mat/0607433 , 175kb)
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\\
arXiv:0811.2030 (*cross-listing*)
replaced with revised version Mon, 30 Mar 2009 07:28:53 GMT (517kb)

Title: A comparative study of dynamical simulation methods for the dissociation
of molecular Bose-Einstein condensates
Authors: S. L. W. Midgley, S. Wuester, M. K. Olsen, M. J. Davis and K. V.
Kheruntsyan
Categories: quant-ph cond-mat.other
Comments: 11 pages, 7 figures, corrected typos, minor content changes
\\ ( http://arxiv.org/abs/0811.2030 , 517kb)
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arXiv:0903.4058
replaced with revised version Sun, 29 Mar 2009 04:10:05 GMT (55kb)

Title: Interaction Effects on Wannier Functions of a Bose-Einstein Condensate
in an Optical Lattice and Implications for Bose-Hubbard Model
Authors: Z. X. Liang, B. B. Hu, and Biao Wu
Categories: cond-mat.str-el
\\ ( http://arxiv.org/abs/0903.4058 , 55kb)
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\\
arXiv:0902.2058
replaced with revised version Thu, 2 Apr 2009 14:13:42 GMT (2457kb)

Title: Multi-resonant spinor dynamics in a Bose-Einstein condensate
Authors: Carsten Klempt, Oliver Topic, Gebremedhn Gebreyesus, Manuel Scherer,
Thorsten Henninger, Philipp Hyllus, Wolfgang Ertmer, Luis Santos, and Jan
Arlt
Categories: quant-ph cond-mat.other
\\ ( http://arxiv.org/abs/0902.2058 , 2457kb)
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\\
arXiv:0809.1468
replaced with revised version Tue, 31 Mar 2009 16:07:44 GMT (566kb)

Title: Bose-Einstein condensation in an optical lattice: A perturbation
approach
Authors: C. Trallero-Giner, V. Lopez-Richard, Ming-Chiang Chung, Andreas
Buchleitner
Categories: cond-mat.other
\\ ( http://arxiv.org/abs/0809.1468 , 566kb)
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\\
arXiv:0902.4119
replaced with revised version Tue, 31 Mar 2009 10:54:09 GMT (34kb)

Title: Multiple condensed phases in attractively interacting Bose systems
Authors: M. M\"annel, K. Morawetz, P. Lipavsk\'y
Categories: cond-mat.stat-mech nucl-th
\\ ( http://arxiv.org/abs/0902.4119 , 34kb)
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\\
arXiv:0807.2002
replaced with revised version Wed, 1 Apr 2009 19:50:15 GMT (162kb)

Title: Effective one-dimensional dynamics of elongated Bose-Einstein
condensates
Authors: A. Mu\~noz Mateo and V. Delgado (Univ. La Laguna)
Categories: cond-mat.other
Comments: Final version published in Annals of Physics; 10 pages, 5 figures
Journal-ref: Annals of Physics 324, 709 (2009)
DOI: 10.1016/j.aop.2008.10.002
\\ ( http://arxiv.org/abs/0807.2002 , 162kb)
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\\
arXiv:0809.3239
replaced with revised version Wed, 1 Apr 2009 18:38:52 GMT (28kb)

Title: Discerning Incompressible and Compressible Phases of Cold Atoms in
Optical Lattices
Authors: V.W. Scarola, L. Pollet, J. Oitmaa, M. Troyer
Categories: cond-mat.other quant-ph
Journal-ref: Phys. Rev. Lett. 102, 135302 (2009)
\\ ( http://arxiv.org/abs/0809.3239 , 28kb)
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\\
arXiv:0903.4858
replaced with revised version Wed, 1 Apr 2009 06:59:43 GMT (452kb)

Title: Feshbach Resonances and Medium Effects in ultracold atomic Gases
Authors: G. M. Bruun
Categories: cond-mat.other
Comments: Presented at the 5th workshop on Critical Stability, Erice, Italy
13-17 October 2008. 8 pages, 3 figures. Figure caption corrected
DOI: 10.1007/s00601-009-0040-9
\\ ( http://arxiv.org/abs/0903.4858 , 452kb)
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\\
arXiv:0903.4549
replaced with revised version Wed, 1 Apr 2009 15:38:33 GMT (871kb)

Title: Photoassociation and coherent transient dynamics in the interaction of
ultracold rubidium atoms with shaped femtosecond pulses - I. Experiment
Authors: Wenzel Salzmann, Terry Mullins, Simone G\"otz, Magnus Albert, Judith
Eng, Roland Wester, and Matthias Weidem\"uller, Fabian Weise, Andrea Merli,
Stefan M. Weber, Franziska Sauer, Ludger W\"oste, and Albrecht Lindinger
Categories: physics.atom-ph physics.chem-ph
\\ ( http://arxiv.org/abs/0903.4549 , 871kb)
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\\
arXiv:0806.0814
replaced with revised version Thu, 2 Apr 2009 14:50:13 GMT (617kb)

Title: Observation of vortex formation in an oscillating trapped Bose-Einstein
condensate
Authors: E. A. L. Henn, J. A. Seman, E. R. F. Ramos, M. Caracanhas, P.
Castilho, E. P. Olimpio, G. Roati, D. V. Magalh\~aes, K. M. F. Magalh\~aes,
V.S. Bagnato
Categories: cond-mat.other cond-mat.mes-hall
Comments: 1 figure added, text modified, accepted for publication Phys. Rev. A
\\ ( http://arxiv.org/abs/0806.0814 , 617kb)
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\\
arXiv:0806.1773
replaced with revised version Thu, 2 Apr 2009 09:50:49 GMT (60kb)

Title: Exact solution for infinitely strongly interacting Fermi gases in tight
waveguides
Authors: Liming Guan, Shu Chen, Yupeng Wang, Zhong-Qi Ma
Categories: cond-mat.str-el cond-mat.stat-mech
Comments: 4 pages, 3 figures, version accepted for publication in Phys. Rev.
Lett
\\ ( http://arxiv.org/abs/0806.1773 , 60kb)
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\\
arXiv:0902.2058
replaced with revised version Thu, 2 Apr 2009 14:13:42 GMT (2457kb)

Title: Multi-resonant spinor dynamics in a Bose-Einstein condensate
Authors: Carsten Klempt, Oliver Topic, Gebremedhn Gebreyesus, Manuel Scherer,
Thorsten Henninger, Philipp Hyllus, Wolfgang Ertmer, Luis Santos, and Jan
Arlt
Categories: quant-ph cond-mat.other
\\ ( http://arxiv.org/abs/0902.2058 , 2457kb)
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\\
arXiv:0903.5343
replaced with revised version Thu, 2 Apr 2009 16:07:24 GMT (315kb)

Title: Repulsive Fermi gas in a harmonic trap: Ferromagnetism and spin textures
Authors: L. J. LeBlanc, J. H. Thywissen, A. A. Burkov, A. Paramekanti
Categories: cond-mat.quant-gas
Comments: 9 pages, 4 figures (minor typos in text+fig corrected)
\\ ( http://arxiv.org/abs/0903.5343 , 315kb)
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Till next time,
Matt.

--
=========================================================================
Dr M. J. Davis,                      Associate Professor in Physics
School of Mathematics and Physics,   ph  : +61 7 334 69824
The University of Queensland,        fax : +61 7 336 51242
Brisbane, QLD 4072,                  mdavis_at_physics.uq.edu.au
Australia.                           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/
=========================================================================
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=========================================================================

Received on Fri May 29 2009 - 08:38:24 EST

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