# Matt's arXiv selection: week ending 28 January 2008.

From: Matthew Davis <mdavis_at_physics.uq.edu.au>
Date: Tue, 29 Jan 2008 20:25:26 +1000

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

It has been a couple of busy weeks... 33 new preprints and 10 replacements this
week:

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arXiv:0801.2795
Date: Thu, 17 Jan 2008 23:43:20 GMT (26kb)

Title: Bose-Einstein condensation in magnetic systems under strong fields
Authors: D. Reyes, M. A. Continentino and A. Paduan-Filho
Categories: cond-mat.str-el
Comments: 4 pages, 1 figure. submitted to PRB
\\
At zero temperature and strong applied magnetic fields the ground sate of an
anisotropic antiferromagnet is a saturated paramagnet with fully aligned spins.
We study the quantum phase transition as the field is reduced below an upper
critical $H_{c2}$ and the system enters a XY-antiferromagnetic phase. Using a
bond operator representation we consider a model spin-1 Heisenberg
antiferromagnetic with single-ion anisotropy in hyper-cubic lattices under
strong magnetic fields. We show that the transition at $H_{c2}$ can be
interpreted as a Bose-Einstein condensation (BEC) of magnons. The theoretical
results are used to analyze our magnetization versus field data in the organic
compound $NiCl_2$-$4SC(NH_2)_2$ (DTN) at very low temperatures. This is the
ideal BEC system to study this transition since $H_{c2}$ is sufficiently low to
be reached with static magnetic fields (as opposed to pulsed fields). The
scaling of the magnetization as a function of field and temperature close to
$H_{c2}$ shows excellent agreement with the theoretical predictions. It allows
to obtain the quantum critical exponents and confirm the BEC nature of the
transition at $H_{c2}$.
\\ ( http://arxiv.org/abs/0801.2795 , 26kb)
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arXiv:0801.2798
Date: Fri, 18 Jan 2008 00:41:04 GMT (38kb)

Title: Heteronuclear fermionic superfluids with spin degrees of freedom
Authors: D. B. M. Dickerscheid, Y. Kawaguchi, M. Ueda
Categories: cond-mat.stat-mech
Comments: Submitted for publication in PRA
\\
We present a theory of spinor superfluidity in a two-species heteronuclear
ultracold fermionic atomic gas consisting of arbitrary half-integer spin and
one-half spin atoms. In particular, we focus on the magnetism of the superfluid
phase and determine the possible phases in the absence of a magnetic field. Our
work demonstrates similarities between heteronuclear fermionic superfluids and
spinor Bose-Einstein condensates at the mean-field level. Possible experimental
situations are discussed.
\\ ( http://arxiv.org/abs/0801.2798 , 38kb)
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arXiv:0801.2872
Date: Fri, 18 Jan 2008 12:28:40 GMT (289kb)

Title: Characterization of reconnecting vortices in superfluid helium
Authors: Gregory P. Bewley, Matthew S. Paoletti, Katepalli R. Sreenivasan, and
Daniel P. Lathrop
Categories: cond-mat.other cond-mat.supr-con
\\
When two vortices cross, each of them breaks into two parts and exchanges
part of itself for part of the other. This process, called vortex reconnection,
occurs in classical as well as superfluids, and in magnetized plasmas and
superconductors. We present the first experimental observations of reconnection
between quantized vortices in superfluid helium. We do so by imaging
micron-sized solid hydrogen particles trapped on quantized vortex cores (Bewley
GP, Lathrop DP, Sreenivasan KR, 2006, Nature, 441:588), and by inferring the
occurrence of reconnection from the motions of groups of recoiling particles.
We show the distance separating particles on the just-reconnected vortex lines
grows as a power law in time. The average value of the scaling exponent is
approximately 1/2, consistent with the scale-invariant evolution of the
vortices.
\\ ( http://arxiv.org/abs/0801.2872 , 289kb)
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arXiv:0801.2910
Date: Fri, 18 Jan 2008 15:34:23 GMT (151kb)

Title: Functional renormalization for Bose-Einstein Condensation
Authors: S. Floerchinger and C. Wetterich
Categories: cond-mat.supr-con
Comments: 21 pages, 16 figures
\\
We investigate Bose-Einstein condensation for interacting bosons at zero and
nonzero temperature. Functional renormalization provides us with a consistent
method to compute the effect of fluctuations beyond the Bogoliubov
approximation. For three dimensional dilute gases, we find an upper bound on
the scattering length a which is of the order of the microphysical scale -
typically the range of the Van der Waals interaction. In contrast to fermions
near the unitary bound, no strong interactions occur for bosons with
approximately pointlike interactions, thus explaining the high quantitative
reliability of perturbation theory for most quantities. For zero temperature we
compute the quantum phase diagram for bosonic quasiparticles with a general
dispersion relation, corresponding to an inverse microphysical propagator with
terms linear and quadratic in the frequency. We compute the temperature
dependence of the condensate and particle density n, and find for the critical
temperature T_c a deviation from the free theory, Delta T_c/T_c = 2.1 a
n^{1/3}. For the sound velocity at zero temperature we find very good agreement
with the Bogoliubov result, such that it may be used to determine the particle
density accurately.
\\ ( http://arxiv.org/abs/0801.2910 , 151kb)
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arXiv:0801.2928
Date: Fri, 18 Jan 2008 16:26:16 GMT (453kb)

Title: Cold atom dynamics in non-Abelian gauge fields
Authors: A. Jacob, P. Ohberg, G. Juzeliunas and L. Santos
Categories: cond-mat.other
Comments: 8 pages, 9 figures
Journal-ref: Appl. Phys. B 89, 439-445 (2007)
\\
The dynamics of ultracold neutral atoms subject to a non-Abelian gauge field
is investigated. In particular we analyze in detail a simple experimental
scheme to achieve a constant, but non-Abelian gauge field, and discuss in the
frame of this gauge field the non-Abelian Aharanov-Bohm effect. In the last
part of this paper, we discuss intrinsic non-Abelian effects in the dynamics of
cold atomic wavepackets.
\\ ( http://arxiv.org/abs/0801.2928 , 453kb)
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arXiv:0801.2935
Date: Fri, 18 Jan 2008 16:45:35 GMT (153kb)

Title: Landau levels of cold atoms in non-Abelian gauge fields
Authors: A. Jacob, P. Ohberg, G. Juzeliunas and L. Santos
Categories: cond-mat.other
Comments: 13 pages, 9 figures
\\
The Landau levels of cold atomic gases in non-Abelian gauge fields are
analyzed. In particular we identify effects on the energy spectrum and density
distribution which are purely due to the non-Abelian character of the fields.
We investigate in detail non-Abelian generalizations of both the Landau and the
symmetric gauge. Finally, we discuss how these non-Abelian Landau and symmetric
gauges may be generated by means of realistically feasible lasers in a tripod
scheme.
\\ ( http://arxiv.org/abs/0801.2935 , 153kb)
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arXiv:0801.2952
Date: Fri, 18 Jan 2008 18:33:23 GMT (964kb)

Title: Rotating trapped Bose-Einstein condensates
Authors: Alexander L. Fetter
Categories: cond-mat.stat-mech
Comments: 44 pages, 18 figures, submitted to Reviews of Modern Physics
\\
After reviewing the ideal Bose-Einstein gas in a box and in a harmonic trap,
I discuss the effect of interactions on the formation of a Bose-Einstein
condensate (BEC), along with the dynamics of small-amplitude perturbations (the
Bogoliubov equations). When the condensate rotates with angular velocity Omega,
one or several vortices nucleate, with many observable consequences. With more
rapid rotation, the vortices form a dense triangular array, and the collective
behavior of these vortices has additional experimental implications. For Omega
near the radial trap frequency omega_perp, the lowest-Landau-level
approximation becomes applicable, providing a simple picture of such rapidly
rotating condensates. Eventually, as Omega approaches omega_perp, the rotating
dilute gas is expected to undergo a quantum phase transition from a superfluid
to various highly correlated (nonsuperfluid) states analogous to those familiar
from the fractional quantum Hall effect for electrons in a strong perpendicular
magnetic field.
\\ ( http://arxiv.org/abs/0801.2952 , 964kb)
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arXiv:0801.2964
Date: Thu, 17 Jan 2008 22:31:18 GMT (430kb)

Title: Vortex Splitting in Subcritical Nonlinear Schrodinger Equation
Authors: Natalia G. Berloff
Categories: cond-mat.other physics.flu-dyn
Comments: Invited submission to the special issue on Vortex Rings, Journal of
Fluid Dynamics Research
\\
Vortices and axisymmetric vortex rings are considered in the framework of the
subcritical nonlinear Schrodinger equations. The higher order nonlinearity
present in such systems models many-body interactions in superfluid systems and
allows one to study the effects of negative pressure on vortex dynamics. We
find the critical pressure for which the straight-line vortex becomes unstable
to radial expansion of the core. The energy of the straight-line vortices and
energy, impulse and velocity of vortex rings are calculated. The effect of a
varying pressure on the vortex core is studied. It is shown that under the
action of the periodically varying pressure field a vortex ring may split into
many vortex rings and the conditions for which this happens are elucidated.
These processes are also relevant to experiments in Bose-Einstein condensates
where the strength and the sign of two-body interactions can be changed via
Feshbach resonance.
\\ ( http://arxiv.org/abs/0801.2964 , 430kb)
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arXiv:0801.2791
Date: Thu, 17 Jan 2008 23:18:13 GMT (277kb)

Title: Versatile two-dimensional potentials for ultra-cold atoms
Authors: S.K. Schnelle, E.D. van Ooijen, M.J. Davis, N.R. Heckenberg and H.
Rubinsztein-Dunlop
Categories: physics.atom-ph
Comments: 8 pages, 5 figures
\\
We propose and investigate a technique for generating smooth two-dimensional
potentials for ultra-cold atoms based on the rapid scanning of a far-detuned
laser beam using a two-dimensional acousto-optical modulator (AOM). We
demonstrate the implementation of a feed-forward mechanism for fast and
accurate control of the spatial intensity of the laser beam, resulting in
improved homogeneity for the atom trap. This technique could be used to
generate a smooth toroidal trap that would be useful for static and dynamic
experiments on superfluidity and persistent currents with ultra-cold atoms.
\\ ( http://arxiv.org/abs/0801.2791 , 277kb)
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arXiv:0801.2943
Date: Fri, 18 Jan 2008 17:26:10 GMT (962kb,D)

Title: Trapping molecules on a chip in traveling potential wells
Authors: Samuel A. Meek, Hendrick L. Bethlem, Horst Conrad, Gerard Meijer
Categories: physics.atom-ph
Comments: 4 pages, 3 figures
\\
A microstructured array of over 1200 electrodes on a substrate has been
configured to generate an array of local minima of electric field strength with
a periodicity of $120 \mu$m about $25 \mu$m above the substrate. By applying
sinusoidally varying potentials to the electrodes, these minima can be made to
move smoothly along the array. Polar molecules in low field seeking quantum
states can be trapped in these traveling potential wells. This is
experimentally demonstrated by transporting metastable CO molecules in 30 mK
deep wells that move at constant velocities above the substrate.
\\ ( http://arxiv.org/abs/0801.2943 , 962kb)
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arXiv:0801.3127
Date: Mon, 21 Jan 2008 05:37:43 GMT (16kb)

Title: Phase Diagram of Cold Polarized Fermi Gas in Two Dimensions
Authors: Lianyi He and Pengfei Zhuang
Categories: cond-mat.supr-con
Comments: 4 pages, 1 figure
\\
The superfluid phase diagrams and bound states in a two-dimensional cold
polarized Fermi gas are systematically and analytically studied. Phase
separation is the energetically favored ground state at finite polarization for
all coupling, and there is no stable gapless phase at strong coupling. Phase
separation appears explicitly in both coupling-Zeeman field and
coupling-polarization planes, and there exist a lower and an upper critical
Zeeman field, in contrast to the well-known result in the weak coupling limit.
The di-fermion bound states can survive in highly polarized normal state even
at weak coupling limit.
\\ ( http://arxiv.org/abs/0801.3127 , 16kb)
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arXiv:0801.3137
Date: Mon, 21 Jan 2008 07:10:52 GMT (11kb)

Title: Analysis on Condition for Emergence of Complex Eigenvalues in the
Bogoliubov-de Gennes Equations
Authors: Y.Nakamura, M.Mine, M.Okumura, and Y.Yamanaka
Categories: cond-mat.other
Comments: 6pages
\\
The condition for the appearance of dynamical instability of the
Bose-condensed system, characterized by the emergence of complex eigenvalues in
the Bogoliubov-de Gennes equations, is studied analytically. We perturbatively
expand both the Gross-Pitaevskii and Bogoliubov-de Gennes equations with
respect to the coupling constant. It is concluded that the degeneracy between a
positive-norm eigenmode and a negative-norm one is essential for the emergence
of complex modes. Based on the conclusion, we justify the two-mode
approximation applied in our previous work [E. Fukuyama \textit{et al}., Phys.
Rev. A {\bf 76}, 043608 (2007)], in which we analytically studied the condition
for the existence of complex modes when the condensate has a highly quantized
vortex.
\\ ( http://arxiv.org/abs/0801.3137 , 11kb)
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arXiv:0801.3154
Date: Mon, 21 Jan 2008 16:53:52 GMT (357kb)

Title: Number squeezing, quantum fluctuations and oscillations in mesoscopic
Bose Josephson junctions
Authors: G. Ferrini, A. Minguzzi, F.W.J. Hekking (UJF-CNRS Grenoble)
Categories: cond-mat.mes-hall
Comments: 4 pages, 3 figures
\\
Starting from a quantum two-mode Bose-Hubbard Hamiltonian we determine the
ground state properties, momentum distribution and dynamical evolution for a
Bose Josephson junction realized by an ultracold Bose gas in a double-well
trap. Varying the well asymmetry we identify Mott-like regions of parameters
where number fluctuations are suppressed and the interference fringes in the
momentum distribution are strongly reduced. We also show how Schroedinger cat
states, realized from an initially phase coherent state by a sudden rise of the
barrier among the two wells, will give rise to a destructive interference in
the time-dependent momentum distribution.
\\ ( http://arxiv.org/abs/0801.3154 , 357kb)
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arXiv:0801.3168
Date: Mon, 21 Jan 2008 10:45:13 GMT (32kb)

Title: Representative statistical ensembles for Bose systems with broken gauge
symmetry
Authors: V.I. Yukalov
Categories: cond-mat.stat-mech
Comments: 43 pages, Latex file
Journal-ref: Ann. Phys. 323 (2008) 461-499
\\
Bose-condensed systems with broken global gauge symmetry are considered. The
description of these systems, as has been shown by Hohenberg and Martin,
possesses an internal inconsistency, resulting in either nonconserving theories
or yielding an unphysical gap in the spectrum. The general notion of
representative statistical ensembles is formulated for arbitrary statistical
systems, equilibrium or not. The principal idea of this notion is the necessity
of taking into account all imposed conditions that uniquely define the given
statistical system. Employing such a representative ensemble for Bose-condensed
systems removes all paradoxes, yielding a completely self-consistent theory,
both conserving and gapless in any approximation. This is illustrated for an
equilibrium uniform Bose system.
\\ ( http://arxiv.org/abs/0801.3168 , 32kb)
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arXiv:0801.3252
Date: Mon, 21 Jan 2008 19:42:02 GMT (313kb)

Title: Adiabatic melting of two-component Mott-insulator states
Authors: M. Rodriguez, S. R. Clark and D. Jaksch
Categories: cond-mat.mes-hall
Comments: 10 pages, 9 figures
\\
We analyze the outcome of a Mott insulator to superfluid transition for a
two-component Bose gas with two atoms per site in an optical lattice in the
limit of slow ramping down the lattice potential. This manipulation of the
initial Mott insulating state transforms local correlations between hyperfine
states of atom pairs into multiparticle correlations extending over the whole
system. We show how to create macroscopic twin Fock states in this way an that,
in general, the obtained superfluid states are highly depleted even for initial
ground Mott insulator states.
\\ ( http://arxiv.org/abs/0801.3252 , 313kb)
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arXiv:0801.3158
Date: Mon, 21 Jan 2008 10:15:26 GMT (157kb)

Title: Precision measurements with polar molecules: the role of the black body
radiation
Authors: Nicolas Vanhaecke (LAC), Olivier Dulieu (LAC)
Categories: physics.atom-ph physics.chem-ph
Proxy: ccsd hal-00208102
Journal-ref: Molecular Physics 105, 11-12 (2007) 1723-1731
DOI: 10.1080/00268970701466261
\\
In the perspective of the outstanding developments of high-precision
measurements of fundamental constants using polar molecules related to ultimate
checks of fundamental theories, we investigate the possibly counterproductive
role of black-body radiation on a series of diatomic molecules which would be
trapped and observed for long durations. We show that the absorption of
black-body radiation at room temperature may indeed limit the lifetime of
trapped molecules prepared in a well-defined quantum state. Several examples
are treated, corresponding to pure rotational absorption, pure vibrational
absorption or both. We also investigate the role of a black-body
radiation-induced energy shift on molecular levels and how it could affect
high-precision frequency measurements.
\\ ( http://arxiv.org/abs/0801.3158 , 157kb)
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arXiv:0801.3255
Date: Mon, 21 Jan 2008 20:18:44 GMT (181kb,D)

Title: A simple integrated single-atom detector
Authors: Marco Wilzbach, Dennis Heine, S\"onke Groth, Xiyuan Liu, Bj\"orn
Hessmo, J\"org Schmiedmayer
Categories: physics.atom-ph physics.optics
Comments: 4 pages, 3 figures
\\
We experimentally implement an integrated detector capable to detect single
atoms with an efficiency of 56% and a signal-to-noise ratio of 275. We
magnetically guide cold atoms through the focus of a tapered lensed fiber,
mounted on the surface of an atom chip, where they are optically excited and
emit bursts of fluorescent photons. Some of these photons are collected by
another chip-mounted fiber and counted by a photon counter. Simple improvements
will allow atom counting with close to unit efficiency.
\\ ( http://arxiv.org/abs/0801.3255 , 181kb)
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arXiv:0801.3307
Date: Tue, 22 Jan 2008 05:15:06 GMT (190kb)

Title: Solitons in two-dimensional Bose-Einstein condensates
Authors: Shunji Tsuchiya, Franco Dalfovo, Lev P. Pitaevskii
Categories: cond-mat.supr-con cond-mat.other
Comments: 4 pages, 4 figures
\\
The excitations of a two-dimensional (2D) Bose-Einstein condensate in the
presence of a soliton are studied by solving the Kadomtsev-Petviashvili
equation which is valid when the velocity of the soliton approaches the speed
of sound. The excitation spectrum is found to contain states which are
localized near the soliton and have a dispersion law similar to the one of the
stable branch of transverse oscillations of a 1D gray soliton in a 2D
condensate. By using the stabilization method we show that these localized
excitations behave as resonant states coupled to the continuum of free
excitations of the condensate.
\\ ( http://arxiv.org/abs/0801.3307 , 190kb)
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arXiv:0801.3424
Date: Tue, 22 Jan 2008 17:27:14 GMT (89kb)

Title: Critical temperature of interacting Bose gases in two and three
dimensions
Authors: S. Pilati, S. Giorgini, N. Prokof'ev
Categories: cond-mat.other
Comments: 4 pages, 5 figures
\\
We calculate the superfluid transition temperature of homogeneous interacting
Bose gases in three and two spatial dimensions using large-scale Path Integral
Monte Carlo simulations (with up to $N=105$ particles). In 3D we investigate
the limits of the universal critical behavior in terms of the scattering length
alone by using different models for the interatomic potential. We find that
this type of universality sets in at small values of the gas parameter $na3 \lesssim 10^{-4}$. This value is different from the estimate $na3 \lesssim 10^{-6}$ for the validity of the asymptotic expansion in the limit of vanishing
$na3$. In 2D we study the Berezinskii-Kosterlitz-Thouless transition of a gas
with hard-core interactions. For this system we find good agreement with the
classical lattice $|\psi|^4$ model up to very large densities. We also explain
the origin of the existing discrepancy between previous studies of the same
problem.
\\ ( http://arxiv.org/abs/0801.3424 , 89kb)
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arXiv:0801.3428
Date: Tue, 22 Jan 2008 17:49:28 GMT (476kb)

Title: Nonlinear dynamics of Bose-condensed gases by means of a low- to
high-density variational approach
Authors: Alexandru I. Nicolin and R. Carretero-Gonzalez
Categories: cond-mat.other
Comments: 11 pages, 12 figures, submitted to Phys. Rev. A, January 2008
\\
We propose a versatile variational method to investigate the spatio-temporal
dynamics of one-dimensional magnetically-trapped Bose-condensed gases. To this
end we employ a \emph{q}-Gaussian trial wave-function that interpolates between
the low- and the high-density limit of the ground state of a Bose-condensed
gas. Our main result consists of reducing the Gross-Pitaevskii equation, a
nonlinear partial differential equation describing the T=0 dynamics of the
condensate, to a set of only three equations: \emph{two coupled nonlinear
ordinary differential equations} describing the phase and the curvature of the
wave-function and \emph{a separate algebraic equation} yielding the generalized
width. Our equations recover those of the usual Gaussian variational approach
(in the low-density regime), and the hydrodynamic equations that describe the
high-density regime. Finally, we show a detailed comparison between the
numerical results of our equations and those of the original Gross-Pitaevskii
equation.
\\ ( http://arxiv.org/abs/0801.3428 , 476kb)
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arXiv:0801.3437
Date: Tue, 22 Jan 2008 18:35:15 GMT (398kb)

Title: Damped Bloch Oscillations of Bose-Einstein Condensates in Disordered
Potential Gradients
Authors: S. Drenkelforth, G. Kleine B\"uning, J. Will, T. Schulte, N. Murray,
W. Ertmer, L. Santos, and J.J. Arlt
Categories: cond-mat.other
Comments: 13 pages, 9 figures
\\
We investigate both experimentally and theoretically disorder induced damping
of Bloch oscillations of Bose-Einstein condensates in optical lattices. The
spatially inhomogeneous force responsible for the damping is realised by a
combination of a disordered optical and a magnetic gradient potential. We show
that the inhomogeneity of this force results in a broadening of the
quasimomentum spectrum, which in turn causes damping of the centre-of-mass
oscillation. We quantitatively compare the obtained damping rates to the
simulations using the Gross-Pitaevskii equation. Our results are relevant for
high precision experiments on very small forces, which require the observation
of a large number of oscillation cycles.
\\ ( http://arxiv.org/abs/0801.3437 , 398kb)
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arXiv:0801.3320
Date: Tue, 22 Jan 2008 08:01:11 GMT (10kb)

Title: Noise induced current in a double-well trap
Authors: S. Anderloni, F. Benatti and R. Floreanini
Categories: quant-ph
Comments: 10 pages, LaTeX
\\
We study the behavior of cold atoms trapped in optical double well potentials
in presence of noise, either generated by an external environment or by the
trap itself. We show that quite in general the noise can induce a current
between the two wells even when tunneling between the two wells is highly
suppressed (Mott insulator phase). An engineered environment could provide a
test ground for the behavior of such a current.
\\ ( http://arxiv.org/abs/0801.3320 , 10kb)
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arXiv:0801.3351
Date: Tue, 22 Jan 2008 11:48:15 GMT (493kb,D)

Title: Multi-layer atom chips for versatile atom micro manipulation
Authors: Martin Trinker, S\"onke Groth, Stefan Haslinger, Stephanie Manz,
Thomas Betz, Israel Bar-Joseph, Thorsten Schumm, J\"org Schmiedmayer
Categories: physics.atom-ph physics.ins-det
Comments: 4 pages, 5 figures
\\
We employ a combination of optical UV- and electron-beam-lithography to
create an atom chip combining sub-micron wire structures with larger
conventional wires on a single substrate. The new multi-layer fabrication
enables crossed wire configurations, greatly enhancing the flexibility in
designing potentials for ultra cold quantum gases and Bose-Einstein
condensates. Large current densities of >6 x 107 A/cm2 and high voltages of
up to 65 V across 0.3 micron gaps are supported by even the smallest wire
structures. We experimentally demonstrate the flexibility of the next
generation atom chip by producing Bose-Einstein condensates in magnetic traps
created by a combination of wires involving all different fabrication methods
and structure sizes.
\\ ( http://arxiv.org/abs/0801.3351 , 493kb)
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arXiv:0801.3362
Date: Tue, 22 Jan 2008 13:37:14 GMT (989kb,D)

Title: AC electric trapping of neutral atoms
Authors: Sophie Schlunk, Adela Marian, Wieland Schoellkopf, Gerard Meijer
Categories: physics.atom-ph
Comments: 10 pages, 13 figures
\\
We study the dynamic behavior of ultracold neutral atoms in a macroscopic ac
electric trap. Confinement in such a trap is achieved by switching between two
saddle-point configurations of the electric field. The gradual formation of a
stably trapped cloud is observed and the trap performance is studied versus
switching frequency and asymmetry of the switching cycle. Additionally, the
electric field in the trap is mapped out by imaging the atom cloud while the
fields are still on. Finally, the phase space acceptance of the trap is probed
by introducing a modified switching cycle. The experimental results are
reproduced using full three-dimensional trajectory calculations.
\\ ( http://arxiv.org/abs/0801.3362 , 989kb)
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arXiv:0801.3465
Date: Tue, 22 Jan 2008 21:44:51 GMT (50kb)

Title: Mixtures of strongly interacting ultracold bosonic atoms in optical
lattices
Authors: P. Buonsante, S.M. Giamapaolo, F. Illuminati, V. Penna and A. Vezzani
Categories: cond-mat.other
Comments: 5 pages, 3 figures
\\
We investigate the properties of a strongly interacting heteronuclear
boson-boson mixture loaded in a realistic optical lattice. In particular, we
numerically reproduce the apparently surprising results of a recent experiment,
providing a simple explanation. Also, we consider the quantum emulsion states
recently studied on ideal homogeneous systems, and discuss their robustness to
the inhomogeneity introduced by the harmonic trapping typical of standard
experimental realizations.
\\ ( http://arxiv.org/abs/0801.3465 , 50kb)
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arXiv:0801.3571
Date: Wed, 23 Jan 2008 13:17:27 GMT (139kb)

Title: Lowest Landau Level vortex structure of a Bose-Einstein condensate
rotating in a harmonic plus quartic trap
Authors: X. Blanc, N. Rougerie
Categories: cond-mat.stat-mech
Comments: 8 pages, 4 figures
\\
We investigate the vortex patterns appearing in a two-dimensional annular
Bose-Einstein condensate rotating in a quadratic plus quartic confining
potential. We show that in the limit of small anharmonicity the
Gross-Pitaevskii energy can be minimized amongst the Lowest Landau Level wave
functions and use this particular form to get theoretical results in the spirit
of [A. Aftalion X. Blanc F. Nier, Phys. Rev. A 73, 011601(R) (2006)]. In
particular, we show that the vortex pattern is infinite but not uniform. We
also compute numerically the complete vortex structure: it is an Abrikosov
lattice strongly distorted near the edges of the condensate with multiply
quantized vortices appearing at the center of the trap.
\\ ( http://arxiv.org/abs/0801.3571 , 139kb)
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arXiv:0801.3631
Date: Wed, 23 Jan 2008 17:46:26 GMT (126kb)

Title: Anderson localization of a Bose-Einstein condensate in a 3D random
potential
Authors: S.E. Skipetrov, A. Minguzzi, B.A. van Tiggelen, B. Shapiro
Categories: cond-mat.dis-nn cond-mat.mes-hall
Comments: 4 pages, 2 figures
\\
We study the effect of Anderson localization on the expansion of a
Bose-Einstein condensate, released from a harmonic trap, in a 3D random
potential. We use scaling arguments and the self-consistent theory of
localization to show that the long-time behavior of the condensate density is
controlled by a single parameter equal to the ratio of the mobility edge and
the chemical potential of the condensate. We find that the two critical
exponents of the localization transition determine the evolution of the
condensate density in time and space.
\\ ( http://arxiv.org/abs/0801.3631 , 126kb)
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arXiv:0801.3398 (*cross-listing*)
Date: Tue, 22 Jan 2008 17:01:19 GMT (54kb)

Title: Stability analysis of $\pi$-kinks in a 0-$\pi$ Josephson junction
Authors: G. Derks, A. Doelman, S.A. van Gils, H. Susanto
Categories: nlin.PS cond-mat.supr-con
Comments: figures are not included due to file size limit
Journal-ref: SIAM J. Appl. Dyn. Syst. 6, 99-141 (2007)
\\
We consider a spatially non-autonomous discrete sine-Gordon equation with
constant forcing and its continuum limit(s) to model a 0-$\pi$ Josephson
junction with an applied bias current. The continuum limits correspond to the
strong coupling limit of the discrete system. The non-autonomous character is
due to the presence of a discontinuity point, namely a jump of $\pi$ in the
sine-Gordon phase. The continuum models admits static solitary waves which are
called $\pi$-kinks and are attached to the discontinuity point. For small
forcing, there are three types of $\pi$-kinks. We show that one of the kinks is
stable and the others are unstable. There is a critical value of the forcing
beyond all static $\pi$-kinks fail to exist. Up to this value, the
(in)stability of the $\pi$-kinks can be established analytically in the strong
coupling limits. Applying a forcing above the critical value causes the
nucleation of $2\pi$-kinks and -antikinks. Besides a $\pi$-kink, the unforced
system also admits a static $3\pi$-kink. This state is unstable in the
continuum models. By combining analytical and numerical methods in the discrete
model, it is shown that the stable $\pi$-kink remains stable, and that the
unstable $\pi$-kinks cannot be stabilized by decreasing the coupling. The
$3\pi$-kink does become stable in the discrete model when the coupling is
sufficiently weak.
\\ ( http://arxiv.org/abs/0801.3398 , 54kb)
------------------------------------------------------------------------------
\\
arXiv:0801.3538
Date: Wed, 23 Jan 2008 09:54:35 GMT (183kb,D)

Title: Bose-Einstein condensation on a superconducting atom chip
Authors: C. Roux, A. Emmert, A. Lupascu, T.Nirrengarten, G. Nogues, M. Brune,
J.-M. Raimond and S. Haroche
Categories: physics.atom-ph
Comments: 4 pages, 4 figures. Accepted for publication in Europhysics Letters
\\
We have produced a Bose-Einstein condensate (BEC) on an atom chip using only
superconducting wires in a cryogenic environment. We observe the onset of
condensation for 104 atoms at a temperature of 100 nK. This result opens the
way for studies of atom losses and decoherence in a BEC interacting with a
superconducting surface. Studies of dipole-blockade with long-lived Rydberg
atoms in a small and dense atomic sample are underway.
\\ ( http://arxiv.org/abs/0801.3538 , 183kb)
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\\
arXiv:0801.3688
Date: Thu, 24 Jan 2008 15:15:03 GMT (110kb)

Title: One-Dimensional Bose Gases with N-Body Attractive Interactions
Authors: E. Fersino, G. Mussardo, and A. Trombettoni
Categories: cond-mat.stat-mech
Comments: 12 pages, 8 Postscript figures
\\
We study the ground state properties of a one-dimensional Bose gas with
N-body attractive contact interactions. By using the explicit form of the
bright soliton solution of a generalized nonlinear Schroedinger equation, we
compute the chemical potential and the ground state energy. For N=3, a
localized soliton wave-function exists only for a critical value of the
interaction strength: in this case the ground state has an infinite degeneracy
that can be parameterized by the chemical potential. The stabilization of the
bright soliton solution by an external harmonic trap is also discussed, and a
comparison with the effect of N-body attractive contact interactions in higher
dimensions is presented.
\\ ( http://arxiv.org/abs/0801.3688 , 110kb)
------------------------------------------------------------------------------
\\
arXiv:0801.3694
Date: Thu, 24 Jan 2008 01:19:42 GMT (84kb)

Title: How to make a bilayer exciton condensate flow
Authors: Jung-Jung Su and A.H. MacDonald
Categories: cond-mat.mes-hall cond-mat.supr-con
Comments: 10 pages, 3 figures
\\
Bose condensation is responsible for many of the most spectacular effects in
physics because it can promote quantum behavior from the microscopic to the
macroscopic world. Bose condensates can be distinguished by the condensing
object; electron-electron Cooper-pairs are responsible for superconductivity,
Helium atoms for superfluidity, and ultracold alkali atoms in vapors for
coherent matter waves. Electron-hole pair (exciton) condensation has maintained
special interest because it has been difficult to realize experimentally, and
because exciton phase coherence is never perfectly spontaneous. Although ideal
condensates can support an exciton supercurrent, it has not been clear how such
a current could be induced or detected, or how its experimental manifestation
would be altered by the phase-fixing exciton creation and annhilation processes
which are inevitably present. In this article we explain how to induce an
exciton supercurrent in separately contacted bilayer condensates, and predict
electrical effects which enable unambiguous detection.
\\ ( http://arxiv.org/abs/0801.3694 , 84kb)
------------------------------------------------------------------------------
\\
arXiv:0801.3795
Date: Thu, 24 Jan 2008 16:36:44 GMT (37kb)

Title: Trapped p-wave superfluids: a local density approach
Authors: M. Iskin and C. J. Williams
Categories: cond-mat.supr-con cond-mat.other
Comments: 4 pages and 4 figures, to be submitted to PRA
\\
The local density approximation is used to study the ground state superfluid
properties of harmonically trapped p-wave Fermi gases as a function of
fermion-fermion attraction strength. While the density distribution is bimodal
on the weakly attracting BCS side, it becomes unimodal with increasing
attraction and saturates towards the BEC side. This non-monotonic evolution is
related to the topological gapless to gapped phase transition, and may be
observed via radio-frequency spectroscopy since quasi-particle transfer current
requires a finite threshold only on the BEC side.
\\ ( http://arxiv.org/abs/0801.3795 , 37kb)
------------------------------------------------------------------------------
\\
arXiv:0801.3842
Date: Thu, 24 Jan 2008 20:51:54 GMT (94kb)

Title: Long-living Bloch oscillations of matter waves in optical lattices
Authors: M. Salerno, V. V. Konotop, Yu. V. Bludov
Categories: cond-mat.other
Comments: Submitted to Phys. Rev. Lett
\\
It is shown that by properly designing the spatial dependence of the
nonlinearity it is possible to induce long-living Bloch oscillations of a
localized wavepacket in a periodic potential. The results are supported both by
analytical and numerical investigations and are interpreted in terms of matter
wave dynamics displaying dozens of oscillation periods without any visible
distortion of the wave packet.
\\ ( http://arxiv.org/abs/0801.3842 , 94kb)
------------------------------------------------------------------------------

The replacements:

------------------------------------------------------------------------------
\\
arXiv:0706.0212
replaced with revised version Thu, 17 Jan 2008 21:50:55 GMT (113kb)

Title: Breakdown of the adiabatic limit in low dimensional gapless systems
Authors: Anatoli Polkovnikov and Vladimir Gritsev
Categories: cond-mat.stat-mech cond-mat.dis-nn hep-th quant-ph
Comments: 11 pages, 5 figures, to appear in Nature Physics (originally
submitted version)
\\ ( http://arxiv.org/abs/0706.0212 , 113kb)
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\\
arXiv:cond-mat/0611490
replaced with revised version Mon, 21 Jan 2008 13:22:26 GMT (175kb)

Title: Static Properties of Trapped Bose Gases at Finite Temperature: I.
Thomas- Fermi Limit
Authors: M. Benarous and H. Chachou Samet
Categories: cond-mat.stat-mech
Comments: 11 pages, 9 figures, revised version
\\ ( http://arxiv.org/abs/cond-mat/0611490 , 175kb)
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\\
arXiv:0712.1265
replaced with revised version Mon, 21 Jan 2008 19:26:46 GMT (214kb)

Title: The trapped two-dimensional Bose gas: from Bose-Einstein condensation to
Berezinskii-Kosterlitz-Thouless physics
Authors: Zoran Hadzibabic (LKB - Lhomond), Peter Kr\"uger (LKB - Lhomond), Marc
Cheneau (LKB - Lhomond), Steffen Patrick Rath (LKB - Lhomond), Jean Dalibard
(LKB - Lhomond)
Categories: cond-mat.other
Comments: 21 pages, 6 figures
Proxy: ccsd hal-00194992
\\ ( http://arxiv.org/abs/0712.1265 , 214kb)
------------------------------------------------------------------------------
\\
arXiv:0705.1256
replaced with revised version Mon, 21 Jan 2008 16:36:39 GMT (344kb)

Title: Memory-built-in quantum teleportation with photonic and atomic qubits
Authors: Yu-Ao Chen, Shuai Chen, Zhen-Sheng Yuan, Bo Zhao, Chih-Sung Chuu,
Joerg Schmiedmayer and Jian-Wei Pan
Categories: quant-ph
Comments: 19 pages 3 figures 1 table
DOI: 10.1038/nphys832
\\ ( http://arxiv.org/abs/0705.1256 , 344kb)
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\\
arXiv:0705.2426
replaced with revised version Tue, 22 Jan 2008 21:48:00 GMT (33kb)

Title: Vortex Lattice Locking in Rotating Two-Component Bose-Einstein
Condensates
Authors: Ryan Barnett, Gil Refael, Mason A. Porter, Hans Peter Buchler
Categories: cond-mat.str-el cond-mat.mes-hall nlin.PS physics.atom-ph
Comments: 4.2 pages
\\ ( http://arxiv.org/abs/0705.2426 , 33kb)
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\\
arXiv:0711.0653
replaced with revised version Wed, 23 Jan 2008 16:59:54 GMT (334kb)

Title: Destroying superfluidity by rotating a Fermi gas at unitarity
Authors: I. Bausmerth, A. Recati, S. Stringari
Categories: cond-mat.soft cond-mat.supr-con
Comments: 5 pages, 4 figures; comments added; 2 figures changed according to
new results; inset Fig.2 corrected; accepted for publication in Phys. Rev.
Lett
\\ ( http://arxiv.org/abs/0711.0653 , 334kb)
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\\
arXiv:0711.2598
replaced with revised version Wed, 23 Jan 2008 18:33:12 GMT (412kb)

Title: Magnetic trapping of a cold Rb-Cs atomic mixture
Authors: M. L. Harris, P. Tierney, S. L. Cornish
Categories: cond-mat.other
Comments: 16 pages, 5 figures Added references, corrected typos, minor changes
to figures and text
\\ ( http://arxiv.org/abs/0711.2598 , 412kb)
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\\
arXiv:0801.2795
replaced with revised version Wed, 23 Jan 2008 19:37:35 GMT (27kb)

Title: Bose-Einstein condensation in antiferromagnets close to the saturation
field
Authors: D. Reyes, M. A. Continentino and A. Paduan-Filho
Categories: cond-mat.str-el
Comments: 4 pages, 1 figure. Accepted for publication in PRB,
\\ ( http://arxiv.org/abs/0801.2795 , 27kb)
------------------------------------------------------------------------------
\\
arXiv:0710.1984
replaced with revised version Thu, 24 Jan 2008 10:49:24 GMT (229kb)

Title: Density Modulations in an Elongated BEC Released from a Disordered
Potential: What Can We Learn ?
Authors: David Cl\'ement (LCFIO), Philippe Bouyer (LCFIO), Alain Aspect
(LCFIO), Laurent Sanchez-Palencia (LCFIO)
Categories: cond-mat.other quant-ph
Proxy: ccsd hal-00178074
\\ ( http://arxiv.org/abs/0710.1984 , 229kb)
------------------------------------------------------------------------------
\\
arXiv:0710.4402
replaced with revised version Wed, 23 Jan 2008 21:24:11 GMT (174kb)

Title: Control of Optical Dynamic Memory Capacity of an Atomic Bose-Einstein
Condensate
Authors: Devrim Tarhan, Alphan Sennaroglu, Ozgur E. Mustecaplioglu
Categories: quant-ph cond-mat.other
Comments: 4 figures, 11 pages
\\ ( http://arxiv.org/abs/0710.4402 , 174kb)
------------------------------------------------------------------------------

Till next time,
Matt.

--
=========================================================================
Dr M. J. Davis,               Senior Lecturer in Physics
School of Physical Sciences,  email: mdavis_at_physics.uq.edu.au
University of Queensland,     ph   : +61 7 334 69824
Brisbane, QLD 4072,           fax  : +61 7 336 51242
Australia.                    http://www.physics.uq.edu.au/people/mdavis/
=========================================================================
Matt's arXiv selection: weekly summary of cold-atom papers from arXiv.org
http://www.physics.uq.edu.au/people/mdavis/matts_arXiv/
=========================================================================
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Received on Fri Feb 01 2008 - 10:16:26 EST

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