Dear subscribers,
This week's selection was compiled by Chao Feng, and contains 36 new
abstracts and 17 replacements.
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arXiv:1003.0854 (*cross-listing*)
Date: Wed, 3 Mar 2010 17:06:45 GMT (55kb,D)
Date (revised v2): Mon, 19 Jul 2010 18:12:41 GMT (94kb)
Title: Multiple scattering of matter waves: an analytic model of the refractive
index for atomic and molecular gases
Authors: Mikhail Lemeshko, Bretislav Friedrich
Categories: physics.atom-ph physics.chem-ph physics.optics quant-ph
Comments: 5 pages, 1 figure, 2 tables
\\
We present an analytic model of the refractive index for matter waves
propagating through atomic or molecular gases. The model, which combines a WKB
treatment of the long range attraction with the Fraunhofer model treatment of
the short range repulsion, furnishes a refractive index in compelling agreement
with recent experiments of Jacquey et al. [Phys. Rev. Lett. 98, 240405 (2007)]
on Li atom matter waves passing through dilute noble gases. We show that the
diffractive contribution, which arises from scattering by a two dimensional
"hard core" of the potential, is essential for obtaining a correct imaginary
part of the refractive index.
\\ ( http://arxiv.org/abs/1003.0854 , 94kb)
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arXiv:1007.2416 (*cross-listing*)
Date: Wed, 14 Jul 2010 20:02:08 GMT (727kb)
Title: Quantum localization without disorder in interacting Bose-Einstein
condensates
Authors: Roberto Franzosi, Salvatore M. Giampaolo, Fabrizio Illuminati
Categories: cond-mat.quant-gas physics.atom-ph quant-ph
Comments: 4 pages, 4 figures
\\
We discuss the possibility of exponential quantum localization in systems of
ultracold bosonic atoms with repulsive interactions in open optical lattices
without disorder. We show that exponential localization occur in the maximally
excited state of the lowest energy band. We establish the conditions under
which the presence of the upper energy bands can be neglected, determine the
successive stages and the quantum phase boundaries at which localization
occurs, and discuss how to detect it experimentally by visibility measurements.
The discussed mechanism is a bona fide type of quantum localization, solely due
to the interplay between nonlinearity and a bounded energy spectrum. In
particular, it does not require the presence of random disorder or other local
sources of noise, in striking contrast with Anderson localization.
\\ ( http://arxiv.org/abs/1007.2416 , 727kb)
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arXiv:1007.2652
Date: Thu, 15 Jul 2010 20:44:18 GMT (49kb)
Title: A Simple Quantum Model of Ultracold Polar Molecule Collisions
Authors: Zbigniew Idziaszek, Goulven Qu\'em\'ener, John L. Bohn, Paul S.
Julienne
Categories: quant-ph cond-mat.quant-gas
\\
We present a unified formalism for describing chemical reaction rates of
trapped, ultracold molecules. This formalism reduces the scattering to its
essential features, namely, a propagation of the reactant molecules through a
gauntlet of long-range forces before they ultimately encounter one another,
followed by a probability for the reaction to occur once they do. In this way,
the electric-field dependence should be readily parametrized in terms of a pair
of fitting parameters (along with a $C_6$ coefficient) for each asymptotic
value of partial wave quantum numbers $|L,M \rangle$. From this, the electric
field dependence of the collision rates follows automatically. We present
examples for reactive species such as KRb, and non-reactive species, such as
RbCs.
\\ ( http://arxiv.org/abs/1007.2652 , 49kb)
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arXiv:1007.2677 (*cross-listing*)
Date: Thu, 15 Jul 2010 23:10:10 GMT (786kb)
Title: Rotating Few-body Atomic Systems in the Fractional Quantum Hall Regime
Authors: Nathan Gemelke, Edina Sarajlic, and Steven Chu
Categories: cond-mat.quant-gas quant-ph
\\
Topologically-ordered matter is a novel quantum state of matter observed only
in a small number of physical systems, notably two-dimensional electron systems
exhibiting fractional quantum Hall effects. It was recently proposed that a
simple form of topological matter may be created in interacting systems of
rotating ultra-cold atoms. We describe ensemble measurements on small, rotating
clusters of interacting bosonic atoms, demonstrating that they can be induced
into quantum ground states closely analogous to topological states of
electronic systems. We report measurements of inter-particle correlations and
momentum distributions of Bose gases in the fractional quantum Hall limit,
making comparison to a full numerical simulation. The novel experimental
apparatus necessary to produce and measure properties of these deeply entangled
quantum states is described.
\\ ( http://arxiv.org/abs/1007.2677 , 786kb)
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arXiv:1007.2682
Date: Thu, 15 Jul 2010 23:51:48 GMT (355kb)
Title: Coherent control of diffuse light dynamics in an ultracold atomic gas
Authors: L.V. Gerasimov, I.M. Sokolov, D.V. Kupriyanov, R.G. Olave, and M.D.
Havey
Categories: quant-ph physics.atom-ph physics.optics
Comments: To appear, Optics Letters (2010)
\\
We show that diffuse light propagation in a disordered atomic medium,
prepared at ultra-low temperatures, can be be effectively delayed in the
presence of a strong control field initiating a stimulated Raman process. On a
time scale of a few milliseconds, when the atomic system can preserve its
configuration, the scattered signal pulse, diffusely propagating through the
medium, can be stored in the spin subsystem via its stimulated Raman-type
conversion into spin coherence. We demonstrate how this mechanism, potentially
interesting for developing quantum memories, would work for the example of a
coherent light pulse propagating through an alkali-metal atomic vapor under
typical conditions attainable in experiments with ultracold atoms.
\\ ( http://arxiv.org/abs/1007.2682 , 355kb)
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arXiv:1007.2690
Date: Fri, 16 Jul 2010 03:22:12 GMT (4468kb)
Title: Controlling phase separation of binary Bose-Einstein condensates via
mixed-spin-channel Feshbach resonance
Authors: Satoshi Tojo, Yoshihisa Taguchi, Yuta Masuyama, Taro Hayashi, Hiroki
Saito, and Takuya Hirano
Categories: cond-mat.quant-gas
Comments: 6 pages, 5 figures
\\
We investigate controlled phase separation of a binary Bose-Einstein
condensate (BEC) in the proximity of mixed-spin-channel Feshbach resonance in
the |F = 1, mF = +1> and |F = 2,mF = -1> states of 87Rb at a magnetic field of
9.10 G. Phase separation occurs on the lower magnetic-field side of the
Feshbach resonance while the two components overlap on the higher
magnetic-field side. The Feshbach resonance curve of the scattering length is
obtained from the shape of the atomic cloud by comparison with the numerical
analysis of coupled Gross-Pitaevskii equations.
\\ ( http://arxiv.org/abs/1007.2690 , 4468kb)
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arXiv:1007.2716
Date: Fri, 16 Jul 2010 08:26:37 GMT (281kb)
Title: Excitations in disordered bosonic optical lattices
Authors: Michael Knap, Enrico Arrigoni, Wolfgang von der Linden
Categories: cond-mat.quant-gas cond-mat.dis-nn
Comments: 6 pages, 6 figures
\\
Spectral excitations of ultracold gases of bosonic atoms trapped in one
dimensional optical lattices with disorder are investigated by means of the
variational cluster approach applied to the Bose-Hubbard model. In particular,
qualitatively different disorder distributions typically employed in
experiments are considered. The computed spectra exhibit a strong dependence on
both the shape of the disorder distribution and the disorder strength. We
compare alternative results for the Mott gap obtained from its formal
definition and from the minimum peak distance, which is the quantity available
from experiments.
\\ ( http://arxiv.org/abs/1007.2716 , 281kb)
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arXiv:1007.2807
Date: Fri, 16 Jul 2010 16:36:46 GMT (717kb)
Title: Disorder in quantum vacuum: Casimir-induced localization of matter waves
Authors: G. A. Moreno, R. Messina, D. A. R. Dalvit, A. Lambrecht, P. A. Maia
Neto and S. Reynaud
Categories: quant-ph cond-mat.quant-gas
\\
Disordered geometrical boundaries such as rough surfaces induce important
modifications to the mode spectrum of the electromagnetic quantum vacuum, and
may generate a disordered Casimir interaction between material bodies. In
analogy to Anderson localization of waves induced by a random potential, here
we show that the Casimir-Polder interaction between a cold atomic sample and a
rough surface also produces localization phenomena. These effects, that
represent a macroscopic manifestation of disorder in quantum vacuum, should be
observable with Bose-Einstein condensates expanding in proximity of rough
surfaces.
\\ ( http://arxiv.org/abs/1007.2807 , 717kb)
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arXiv:1007.2890
Date: Sat, 17 Jul 2010 00:56:54 GMT (169kb)
Title: Phonon-mediated Josephson oscillations in excitonic and polaritonic
condensates
Authors: E.B. Magnusson, H. Flayac, G. Malpuech and I.A. Shelykh
Categories: cond-mat.quant-gas
Comments: 10 pages, Submitted to Phys. Rev. B
\\
We analyze theoretically the role of the exciton-phonon interactions in
phenomena related to the Josephson effect between two spatially separated
exciton and exciton-polariton condensates. We consider the role of the
dephasing introduced by phonons in such phenomena as Josephson tunneling,
self-trapping and spontaneous polarization separation. In the regime of cw
pumping we find a remarkable bistability effect arising from exciton- exciton
interactions as well as regimes of self- sustained regular and chaotic
oscillations.
\\ ( http://arxiv.org/abs/1007.2890 , 169kb)
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arXiv:1007.2891
Date: Sat, 17 Jul 2010 01:03:37 GMT (1660kb)
Title: Rotons in a hybrid Bose-Fermi system
Authors: I.A. Shelykh, T. Taylor and A.V. Kavokin
Categories: cond-mat.quant-gas
Comments: 4 pages, submitted to Phys. Rev. Lett
\\
We calculate the spectrum of elementary excitations in a two-dimensional
exciton superfluid in the vicinity of a two-dimensional electron gas. We show
that attraction of excitons due to their scattering with free electrons may
lead to formation of a roton minimum. The energy of this minimum may go below
the ground state energy which manifests breaking of the superfluidity. The
Berezinsky-Kosterlitz-Thouless phase transition temperature decreases due to
the exciton-exciton attraction mediated by electrons.
\\ ( http://arxiv.org/abs/1007.2891 , 1660kb)
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arXiv:1007.2912 (*cross-listing*)
Date: Sat, 17 Jul 2010 08:49:07 GMT (518kb)
Title: Direct Forced Evaporative Cooling in Permanent Magnetic Microtraps
Authors: Amir Mohammadi, Saeed Ghanbari and Aref Pariz
Categories: cond-mat.quant-gas physics.atom-ph
Comments: 4 pages and 4 figures
\\
We propose two simple permanent magnetic micro-structures for creating single
Ioffe-Pritchard magnetic microtraps. Direct forced evaporative cooling of
neutral atoms without using spin flips can be implemented in these
microstructures to attain Bose-Einstein condensation (BEC). A BEC critical
temperature of $\sim 10 \mu$K is numerically obtained for $^{87}$Rb atoms in
the atom chips. A bias magnetic field is used to vary the depth of the trap,
frequencies and the minimum of the potential. Even without the external
magnetic field, it is possible to hold ultracold atoms in the microtraps.
Therefore, after achieving the BEC in the atom chips, the bias magnetic field
can be slowly removed to increase the trap barrier heights for more efficiently
holding the Bose-Einstein condensate.
\\ ( http://arxiv.org/abs/1007.2912 , 518kb)
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arXiv:1007.2936
Date: Sat, 17 Jul 2010 15:35:57 GMT (874kb)
Title: Optical probing of correlation driven liquid-to-insulator transition in
2D electron gas
Authors: F. Dionigi, F. Rossella, V. Bellani, M. Amado, E. Diez, K. Kowalik, G.
Biasiol and L. Sorba
Categories: cond-mat.str-el cond-mat.quant-gas
\\
We study the optical emission in an high mobility two dimensional electron
gas at intermediate density in the quantum Hall regime at the liquid-insulator
transition. For nu > 2 the emission from the liquid follows a Landau dispersion
with a screened magneto-Coulomb contribution while for 2 > nu > 1/3 the hidden
symmetry manifests. Above nu = 1/3 the electrons correlate into an insulating
phase with an increased renormalized mass, and the liquid-insulator transition
is coherent with a charge ordering driven by Coulomb correlations, which
conciliate the Wigner and Mott scenarios.
\\ ( http://arxiv.org/abs/1007.2936 , 874kb)
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arXiv:1007.3063
Date: Mon, 19 Jul 2010 06:05:37 GMT (792kb)
Title: Synergy Dynamics of Vortices and Solitons in Atomic Bose-Einstein
Condensate Excited by an Oscillating Potential
Authors: Kazuya Fujimoto and Makoto Tsubota
Categories: cond-mat.quant-gas
Comments: 4 pages, 3 figures
\\
The hydrodynamics of quantized vortices and solitons in an atomic
Bose-Einstein condensate excited by an oscillating potential are studied by
numerically solving the two-dimensional Gross-Pitaevskii equation. The
oscillating potential keeps nucleating vortex dipoles, whose impulses
alternatively change their direction synchronously with the oscillation of the
potential. This leads to synergy dynamics of vortices and solitons which have
not been previously reported in quantum fluids.
\\ ( http://arxiv.org/abs/1007.3063 , 792kb)
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arXiv:1007.3180 (*cross-listing*)
Date: Mon, 19 Jul 2010 15:19:59 GMT (18kb)
Title: Variational methods with coupled Gaussian functions for Bose-Einstein
condensates with long-range interactions. I. General concept
Authors: Stefan Rau, J\"org Main, G\"unter Wunner
Categories: cond-mat.quant-gas nlin.CD quant-ph
Comments: 10 pages, submitted to Phys. Rev. A
\\
The variational method of coupled Gaussian functions is applied to
Bose-Einstein condensates with long-range interactions. The time-dependence of
the condensate is described by dynamical equations for the variational
parameters. We present the method and analytically derive the dynamical
equations from the time-dependent Gross-Pitaevskii equation. The stability of
the solutions is investigated using methods of nonlinear dynamics. The concept
presented in this paper will be applied to Bose-Einstein condensates with
monopolar 1/r and dipolar 1/r^3 interaction in the subsequent paper [S. Rau et
al., Phys. Rev. A, submitted], where we will present a wealth of new phenomena
obtained by using the ansatz with coupled Gaussian functions.
\\ ( http://arxiv.org/abs/1007.3180 , 18kb)
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arXiv:1007.3182 (*cross-listing*)
Date: Mon, 19 Jul 2010 15:25:04 GMT (1458kb,D)
Title: Variational methods with coupled Gaussian functions for Bose-Einstein
condensates with long-range interactions. II. Applications
Authors: Stefan Rau, J\"org Main, Holger Cartarius, Patrick K\"oberle, G\"unter
Wunner
Categories: cond-mat.quant-gas nlin.CD quant-ph
Comments: 14 pages, 14 figures, submitted to Phys. Rev. A
\\
Bose-Einstein condensates with an attractive 1/r interaction and with
dipole-dipole interaction are investigated in the framework of the Gaussian
variational ansatz introduced by S. Rau, J. Main, and G. Wunner [Phys. Rev. A,
submitted]. We demonstrate that the method of coupled Gaussian wave packets is
a full-fledged alternative to direct numerical solutions of the
Gross-Pitaevskii equation, or even superior in that coupled Gaussians are
capable of producing both, stable and unstable states of the Gross-Pitaevskii
equation, and thus of giving access to yet unexplored regions of the space of
solutions of the Gross-Pitaevskii equation. As an alternative to numerical
solutions of the Bogoliubov-de Gennes equations, the stability of the
stationary condensate wave functions is investigated by analyzing the stability
properties of the dynamical equations of motion for the Gaussian variational
parameters in the local vicinity of the stationary fixed points. For
blood-cell-shaped dipolar condensates it is shown that on the route to collapse
the condensate passes through a pitchfork bifurcation, where the ground state
itself turns unstable, before it finally vanishes in a tangent bifurcation.
\\ ( http://arxiv.org/abs/1007.3182 , 1458kb)
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arXiv:1007.3191
Date: Mon, 19 Jul 2010 15:54:34 GMT (3kb)
Title: On role of symmetries in Kelvin wave turbulence
Authors: V. V. Lebedev, V. S. L'vov and S. V. Nazarenko
Categories: cond-mat.other
\\
E.V. Kozik and B.V. Svistunov (KS) paper "Symmetries and Interaction
Coefficients of Kelvin waves", arXiv:1006.1789v1, [cond-mat.other] 9 Jun 2010,
contains a comment on paper "Symmetries and Interaction coefficients of Kelvin
waves", V. V. Lebedev and V. S. L'vov, arXiv:1005.4575, 25 May 2010. It relies
mainly on the KS text "Geometric Symmetries in Superfluid Vortex Dynamics}",
arXiv:1006.0506v1 [cond-mat.other] 2 Jun 2010. The main claim of KS is that a
symmetry argument prevents linear in wavenumber infrared asymptotics of the
interaction vertex and thereby implies locality of the Kelvin wave spectrum
previously obtained by these authors. In the present note we reply to their
arguments. We conclude that there is neither proof of locality nor any
refutation of the possibility of linear asymptotic behavior of interaction
vertices in the texts of KS.
\\ ( http://arxiv.org/abs/1007.3191 , 3kb)
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arXiv:1007.3200
Date: Mon, 19 Jul 2010 16:23:27 GMT (500kb,D)
Title: Bose-Einstein condensation at finite momentum and magnon condensation in
thin film ferromagnets
Authors: Johannes Hick, Francesca Sauli, Andreas Kreisel, Peter Kopietz
Categories: cond-mat.quant-gas cond-mat.str-el
Comments: 9 pages, 4 figures
\\
We use the Gross-Pitaevskii equation to determine the spatial structure of
the condensate density of interacting bosons whose energy dispersion epsilon_k
has two degenerate minima at finite wave-vectors q. We show that in general the
Fourier transform of the condensate density has finite amplitudes for all
integer multiples of q. If the interaction is such that many Fourier components
contribute, the Bose condensate is localized at the sites of a one-dimensional
lattice with spacing 2pi/q; in this case Bose-Einstein condensation resembles
the transition from a liquid to a crystalline solid. We use our results to
investigate the spatial structure of the Bose condensate formed by magnons in
thin films of ferromagnets with dipole-dipole interactions.
\\ ( http://arxiv.org/abs/1007.3200 , 500kb)
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arXiv:1007.3245 (*cross-listing*)
Date: Mon, 19 Jul 2010 19:07:06 GMT (930kb,D)
Title: Anisotropic sub-Doppler laser cooling in dysprosium magneto-optical
traps
Authors: Seo Ho Youn, Mingwu Lu, and Benjamin L. Lev
Categories: physics.atom-ph quant-ph
Comments: 4 pages, 5 figures
\\
Magneto-optical traps (MOTs) of Er and Dy have recently been shown to exhibit
population-wide sub-Doppler cooling due to their near degeneracy of excited and
ground state Lande g factors. We discuss here an additional, unusual intra-MOT
sub-Doppler cooling mechanism that appears when the total Dy MOT cooling laser
intensity and magnetic quadrupole gradient increase beyond critical values.
Specifically, anisotropically sub-Doppler-cooled cores appear, and their
orientation with respect to the quadrupole axis flips at a critical ratio of
the MOT laser intensity along the quadrupole axis versus that in the plane of
symmetry. This phenomenon can be traced to a loss of the velocity-selective
resonance at zero velocity in the cooling force along directions in which the
atomic polarization is oriented by the quadrupole field. We present data
characterizing this anisotropic laser cooling phenomenon and discuss a
qualitative model for its origin based on the extraordinarily large Dy magnetic
moment and Dy's near degenerate g factors.
\\ ( http://arxiv.org/abs/1007.3245 , 930kb)
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arXiv:1007.3307
Date: Mon, 19 Jul 2010 23:28:10 GMT (148kb)
Title: Superfluid gap formation in a fermionic optical lattice with spin
imbalanced populations
Authors: Akihisa Koga and Philipp Werner
Categories: cond-mat.quant-gas
Comments: 4 pages, 1 figure, To appear in J. Phys.: Conf. Ser. for SCES2010
\\
We investigate the attractive Hubbard model in infinite spatial dimensions at
quarter filling. By combining dynamical mean-field theory with continuous-time
quantum Monte Carlo simulations in the Nambu formalism, we directly deal with
the superfluid phase in the population imbalanced system. We discuss the low
energy properties in the polarized superfluid state and the pseudogap behavior
in the vicinity of the critical temperature.
\\ ( http://arxiv.org/abs/1007.3307 , 148kb)
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arXiv:1007.3391
Date: Tue, 20 Jul 2010 10:48:31 GMT (260kb,D)
Title: Quantum memory for light via stimulated off-resonant Raman process:
beyond the three-level Lambda-scheme approximation
Authors: Alexandra S. Sheremet, Leonid V. Gerasimov, Igor M. Sokolov, Dmitriy
V. Kupriyanov (Department of Theoretical Physics, State Polytechnic
University, St.-Petersburg, Russia), Oxana S. Mishina, Elisabeth Giacobino,
Julien Laurat (Universite Pierre et Marie Curie, Ecole Normale Superieure,
CNRS, Case 74, Paris Cedex 05, France)
Categories: quant-ph
Comments: 8 pages, 6 figures
\\
We consider a quantum memory scheme based on the conversion of a signal pulse
into a long-lived spin coherence via stimulated off-resonant Raman process. For
a storing medium consisting of alkali atoms, we have calculated the
Autler-Townes resonance structure created by a strong control field. By taking
into account the upper hyperfine states of the D1 optical transition, we show
important deviations from the predictions of the usual three-level
Lambda-scheme approximation and we demonstrate an enhancement of the process
for particular detunings of the control. We estimate the memory efficiency one
can obtain using this configuration.
\\ ( http://arxiv.org/abs/1007.3391 , 260kb)
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arXiv:1007.3420
Date: Tue, 20 Jul 2010 13:33:37 GMT (392kb,D)
Title: Driven Dissipative d-Wave Pairing of Atomic Fermions
Authors: S. Diehl, W. Yi, A. J. Daley, P. Zoller
Categories: cond-mat.quant-gas cond-mat.str-el
Comments: 5 pages, 3 figures
\\
We show how dissipative dynamics can give rise to pairing for two-component
fermions on a lattice. In particular, we construct a "parent" Liouvillian
operator so that a BCS-type state of a given symmetry, e.g. a d-wave state, is
reached for arbitrary initial states in the absence of conservative forces. The
system-bath couplings describe single-particle, number conserving and
quasi-local processes. The pairing mechanism crucially relies on Fermi
statistics. We show how such Liouvillians can be realized via reservoir
engineering with cold atoms representing a driven dissipative dynamics.
\\ ( http://arxiv.org/abs/1007.3420 , 392kb)
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arXiv:1007.3432 (*cross-listing*)
Date: Tue, 20 Jul 2010 14:29:57 GMT (310kb)
Title: Toward large-scale Hybrid Monte Carlo simulations of the Hubbard model
on graphics processing units
Authors: Kyle A. Wendt, Joaqu\'{\i}n E. Drut, Timo A. L\"ahde
Categories: cond-mat.stat-mech physics.comp-ph
Comments: 8 pages, 5 figures
\\
The performance of the Hybrid Monte Carlo algorithm is determined by the
speed of sparse matrix-vector multiplication within the context of
preconditioned conjugate gradient iteration. We study these operations as
implemented for the fermion matrix of the Hubbard model in d+1 space-time
dimensions, and report a performance comparison between a 2.66 GHz Intel Xeon
E5430 CPU and an NVIDIA Tesla C1060 GPU using double-precision arithmetic. We
find speedup factors ranging between 30-350 for d = 1, and in excess of 40 for
d = 3. We argue that such speedups are of considerable impact for large-scale
simulational studies of quantum many-body systems.
\\ ( http://arxiv.org/abs/1007.3432 , 310kb)
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arXiv:1007.3452
Date: Tue, 20 Jul 2010 15:40:41 GMT (7kb)
Title: Tan Relations in Dilute Bose Gasses
Authors: Adriaan M. J. Schakel
Categories: cond-mat.quant-gas
Comments: 4 pages, no figures
\\
The exact relations for strongly interacting Fermi gasses, recently derived
by Tan, are shown to first order in the loop expansion to also apply to dilute
Bose gasses. A simple thermodynamic argument is put forward to support their
validity. As an application, the second-order correction to the depletion of
the condensate is determined to logarithmic accuracy.
\\ ( http://arxiv.org/abs/1007.3452 , 7kb)
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arXiv:1007.3470 (*cross-listing*)
Date: Tue, 20 Jul 2010 17:51:16 GMT (41kb)
Title: On the numerical integration of the Gross-Pitaevskii equation using
Hermite-Fourier methods
Authors: Philipp Bader and Sergio Blanes
Categories: math.NA cond-mat.other math-ph math.MP
Comments: 9 pages of RevTex4-1, 6 figures; as submitted to journal
\\
We consider the numerical integration of the Gross-Pitaevskii equation with a
potential trap given by a harmonic potential or a small perturbation to it.
Splitting methods are frequently used with Fourier techniques since the system
can be split into the kinetic and remaining part, and each part can be solved
efficiently using Fast Fourier Transforms. To split the system into the quantum
harmonic oscillator problem and the remaining part allows to get higher
accuracies in many cases, but it requires to change between Hermite basis
functions and the coordinate space. We show how to build new methods which
combine the advantages of using Fourier methods while solving the harmonic
oscillator exactly.
\\ ( http://arxiv.org/abs/1007.3470 , 41kb)
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arXiv:1007.3513 (*cross-listing*)
Date: Tue, 20 Jul 2010 21:08:13 GMT (68kb)
Title: Status of the Radial Schrodinger Equation
Authors: Anzor A.Khelashvili and Teimuraz P. Nadareishvili
Categories: math-ph hep-th math.MP quant-ph
Comments: 6 pages
\\
We show that equation for radial wave function in its traditional form is
compatible with the full Schrodinger equation if and only if a definite
additional condition is required. This condition has a boundary condition form
at the origin. Some of consequences are also discussed.
\\ ( http://arxiv.org/abs/1007.3513 , 68kb)
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arXiv:1007.3529
Date: Tue, 20 Jul 2010 22:10:37 GMT (807kb)
Title: Measuring the equation of state of trapped ultracold bosonic systems in
an optical lattice with in-situ density imaging
Authors: Ping Nang Ma, Lode Pollet, Matthias Troyer
Categories: cond-mat.quant-gas
Comments: 8 pages, 10 figures
\\
We analyze quantitatively how imaging techniques with single-site resolution
allow to measure thermodynamical properties that cannot be inferred from
time-of-light images for the trapped Bose-Hubbard model. If the normal state
extends over a sufficiently large range, the chemical potential and the
temperature can be extracted from a single shot, provided the sample is in
thermodynamic equilibrium. When the normal state is too narrow, temperature is
low but can still be extracted using the fluctuation-dissipation theorem over
the entire trap range as long as the local density approximation remains valid,
as was recently suggested by Qi Zhou and Tin-Lun Ho [arXiv:0908.3015]. However,
for typical present-day experiments, the number of samples needed is of the
order of 1000 in order to get the temperature at least $10 \%$ accurate, but it
is possible to reduce the variance by 2 orders of magnitude if the
density-density correlation length is short, which is the case for the
Bose-Hubbard model. Our results provide further evidence that cold gases in an
optical lattices can be viewed as quantum analog computers.
\\ ( http://arxiv.org/abs/1007.3529 , 807kb)
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arXiv:1007.3547
Date: Wed, 21 Jul 2010 01:16:22 GMT (1241kb)
Title: Spectral Properties Near the Mott Transition in the One-Dimensional
Hubbard Model
Authors: Masanori Kohno
Categories: cond-mat.str-el cond-mat.stat-mech
Comments: 4 pages, 2 figures, accepted for publication in Physical Review
Letters
\\
Single-particle spectral properties near the Mott transition in the
one-dimensional Hubbard model are investigated using the dynamical
density-matrix renormalization group method and the Bethe ansatz. The
pseudogap, hole-pocket behavior, spectral-weight transfer, and upper Hubbard
band are explained in terms of spinons, holons, antiholons, and doublons. The
Mott transition is characterized by the emergence of a gapless mode whose
dispersion relation extends up to the order of hopping t (spin exchange J) in
the weak (strong) interaction regime caused by infinitesimal doping.
\\ ( http://arxiv.org/abs/1007.3547 , 1241kb)
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arXiv:1007.3548 (*cross-listing*)
Date: Wed, 21 Jul 2010 01:30:39 GMT (130kb,D)
Title: Kelvin-Tkachenko waves of few-vortex arrays in trapped Bose-Einstein
condensates
Authors: T.P. Simula and K. Machida
Categories: cond-mat.quant-gas quant-ph
Comments: 4 pages, 3 figures
\\
We have calculated the low-lying elementary excitations of three-dimensional
few-vortex arrays in trapped Bose-Einstein condensates. The number of different
Kelvin-Tkachenko vortex wave branches matches the number of vortices in the
condensate. The lowest odd-parity modes exhibit superfluid gyroscopic vortex
motion. Experimentally, these modes could be excited and observed individually
or in connection with the formation and decay of quantum turbulence.
\\ ( http://arxiv.org/abs/1007.3548 , 130kb)
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arXiv:1007.3551 (*cross-listing*)
Date: Wed, 21 Jul 2010 01:50:34 GMT (236kb,D)
Title: Rotating Dipolar Spin-1 Bose-Einstein Condensates
Authors: T. P. Simula, J. A. M. Huhtam\"aki, M. Takahashi, T. Mizushima, and K.
Machida
Categories: cond-mat.quant-gas quant-ph
Comments: 4 pages, 4 figures
\\
We have computed phase diagrams for rotating spin-1 Bose-Einstein condensates
with long-range magnetic dipole-dipole interactions. Spin textures including
vortex sheets, staggered half-quantum- and skyrmion vortex lattices and higher
order topological defects have been found. These systems exhibit both
superfluidity and magnetic crystalline ordering and they could be realized
experimentally by imparting angular momentum in the condensate.
\\ ( http://arxiv.org/abs/1007.3551 , 236kb)
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\\
arXiv:1007.3561
Date: Wed, 21 Jul 2010 05:06:03 GMT (1003kb)
Title: Introduction to Xgrid: Cluster Computing for Everyone
Authors: Barbara J. Breen and John F. Lindner
Categories: physics.comp-ph cs.DC
\\
Xgrid is the first distributed computing architecture built into a desktop
operating system. It allows you to run a single job across multiple computers
at once. All you need is at least one Macintosh computer running Mac OS X v10.4
or later. (Mac OS X Server is not required.) We provide explicit instructions
and example code to get you started, including examples of how to distribute
your computing jobs, even if your initial cluster consists of just two old
laptops in your basement.
\\ ( http://arxiv.org/abs/1007.3561 , 1003kb)
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\\
arXiv:1007.3694
Date: Wed, 21 Jul 2010 17:03:26 GMT (87kb)
Title: Finite temperature damping of collective modes of a BCS-BEC crossover
superfluid
Authors: Zixu Zhang and W. Vincent Liu
Categories: cond-mat.quant-gas cond-mat.str-el
Comments: 8 pages, 4 figures
\\
A new mechanism is proposed to explain the puzzling damping of collective
excitations, which was recently observed in the experiments of strongly
interacting Fermi gases below the superfluid critical temperature on the
fermionic (BCS) side of Feshbach resonance. Sound velocity, superfluid density
and damping rate are calculated with effective field theory. We find that a
dominant damping process is due to the interaction between superfluid phonons
and thermally excited fermionic quasiparticles, in contrast to the previously
proposed pair-breaking mechanism. Results from our effective model are compared
quantitatively with recent experimental findings, showing a good agreement.
\\ ( http://arxiv.org/abs/1007.3694 , 87kb)
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\\
arXiv:1007.3713
Date: Wed, 21 Jul 2010 18:40:42 GMT (913kb)
Title: Probing three-body correlations in a quantum gas red using the
measurement of the third moment of density fluctuations
Authors: Julien Armijo (LCFIO), Thibaut Jacqmin (LCFIO), Karen Kheruntsyan,
Isabelle Bouchoule (LCFIO)
Categories: cond-mat.quant-gas
Comments:
\\
We perform measurements of the third moment of atom number fluctuations in
small slices of a very elongated weakly interacting degenerate Bose gas. We
find a positive skewness of the atom number distribution in the ideal gas
regime and a reduced skewness compatible with zero in the quasi-condensate
regime. For our parameters, the third moment is a thermodynamic quantity whose
measurement constitutes a sensitive test of the equation of state and our
results are in agreement with a modified Yang-Yang thermodynamic prediction.
Moreover, we show that the measured skewness reveals the presence of true three
body correlations in the system.
\\ ( http://arxiv.org/abs/1007.3713 , 913kb)
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\\
arXiv:1007.3828 (*cross-listing*)
Date: Thu, 22 Jul 2010 08:36:31 GMT (305kb)
Title: Phonon resonances in atomic currents through lattice Bose-Fermi mixtures
Authors: M. Bruderer, T. H. Johnson, S. R. Clark, D. Jaksch, A. Posazhennikova,
W. Belzig
Categories: cond-mat.quant-gas quant-ph
Comments: 8 pages, 5 figures
\\
We present an analysis of Bose-Fermi mixtures in optical lattices for the
case where the lattice potential of the fermions is tilted and the bosons (in
the superfluid phase) are described by Bogoliubov phonons. It is shown that the
Bogoliubov phonons enable hopping transitions between fermionic Wannier-Stark
states; these transitions are accompanied by energy dissipation into the
superfluid and result in a net atomic current along the lattice. We derive a
general expression for the drift velocity of the fermions and find that the
dependence of the atomic current on the lattice tilt exhibits negative
differential conductance (NDC) and phonon resonances. Numerical simulations of
the full dynamics of the system based on the time-evolving block decimation
(TEBD) algorithm reveal that the phonon resonances should be observable under
the conditions of a realistic measuring procedure.
\\ ( http://arxiv.org/abs/1007.3828 , 305kb)
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\\
arXiv:1007.3840
Date: Thu, 22 Jul 2010 09:47:18 GMT (1671kb)
Title: Superfluid density of states and pseudogap phenomenon in the BCS-BEC
crossover regime of a superfluid Fermi gas
Authors: Ryota Watanabe, Shunji Tsuchiya, and Yoji Ohashi
Categories: cond-mat.quant-gas
Comments: 22 pages, 8 figures
\\
We investigate single-particle excitations and strong-coupling effects in the
BCS-BEC crossover regime of a superfluid Fermi gas. Including phase and
amplitude fluctuations of the superfluid order parameter within a $T$-matrix
theory, we calculate the superfluid density of states (DOS), as well as
single-particle spectral weight, over the entire BCS-BEC crossover region below
the superfluid transition temperature $T_{\rm c}$. We clarify how the pseudogap
in the normal state evolves into the superfluid gap, as one passes through
$T_{\rm c}$. While the pseudogap in DOS continuously evolves into the
superfluid gap in the weak-coupling BCS regime, the superfluid gap in the
crossover region is shown to appear in DOS after the pseudogap disappears below
$T_{\rm c}$. In the phase diagram with respect to the temperature and
interaction strength, we determine the region where strong pairing fluctuations
dominate over single-particle properties of the system. Our results would be
useful for the study of strong-coupling phenomena in the BCS-BEC crossover
regime of a superfluid Fermi gas.
\\ ( http://arxiv.org/abs/1007.3840 , 1671kb)
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arXiv:1007.3895 (*cross-listing*)
Date: Thu, 22 Jul 2010 14:39:31 GMT (52kb,D)
Title: Atom-dimer scattering length for fermions with different masses:
analytical study of limiting cases
Authors: F. Alzetto, R. Combescot and X. Leyronas
Categories: cond-mat.quant-gas quant-ph
Comments: 15 pages, 4 figures
\\
We consider the problem of obtaining the scattering length for a fermion
colliding with a dimer, formed from a fermion identical to the incident one and
another different fermion. This is done in the universal regime where the range
of interactions is short enough so that the scattering length $a$ for non
identical fermions is the only relevant quantity. This is the generalization to
fermions with different masses of the problem solved long ago by Skorniakov and
Ter-Martirosian for particles with equal masses. We solve this problem
analytically in the two limiting cases where the mass of the solitary fermion
is very large or very small compared to the mass of the two other identical
fermions. This is done both for the value of the scattering length and for the
function entering the Skorniakov-Ter-Martirosian integral equation, for which
simple explicit expressions are obtained.
\\ ( http://arxiv.org/abs/1007.3895 , 52kb)
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The replacements:
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arXiv:1006.1269
replaced with revised version Mon, 19 Jul 2010 08:55:01 GMT (483kb)
Title: Incompressible states of a two-component Fermi gas in a double-well
optical lattice
Authors: Fran\c{c}ois Cr\'epin, Roberta Citro and Pascal Simon
Categories: cond-mat.quant-gas
Comments: 10 pages, 7 figures. Published in Phys. Rev. A
Journal-ref: Phys. Rev. A 82, 013613 (2010)
DOI: 10.1103/PhysRevA.82.013613
\\ ( http://arxiv.org/abs/1006.1269 , 483kb)
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\\
arXiv:0912.5022
replaced with revised version Mon, 19 Jul 2010 12:04:00 GMT (1577kb,D)
Title: Temporal coherence, anomalous moments, and pairing correlations in the
classical-field description of a degenerate Bose gas
Authors: T. M. Wright, P. B. Blakie, and R. J. Ballagh
Categories: cond-mat.quant-gas
Comments: 11 pages, 6 figures. v3: Final version. Typos fixed, and other minor
changes
Journal-ref: Phys. Rev. A 82, 013621 (2010)
DOI: 10.1103/PhysRevA.82.013621
\\ ( http://arxiv.org/abs/0912.5022 , 1577kb)
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\\
arXiv:1005.2420
replaced with revised version Mon, 19 Jul 2010 15:41:10 GMT (345kb)
Title: Comment on "Inequivalence between the Schrodinger equation and the
Madelung hydrodynamic equations"
Authors: Vel Hushwater
Categories: quant-ph
Comments: Paper was shortened - only one method of the proof was left.
Presentation was improved, some notations were corrected. Note [4] was
improved
\\ ( http://arxiv.org/abs/1005.2420 , 345kb)
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\\
arXiv:1002.3696
replaced with revised version Mon, 19 Jul 2010 15:47:50 GMT (168kb)
Title: Anderson localization vs. Mott-Hubbard metal-insulator transition in
disordered, interacting lattice fermion systems
Authors: K. Byczuk, W. Hofstetter, and D. Vollhardt
Categories: cond-mat.str-el cond-mat.dis-nn
Comments: 25 pages, 5 figures, typos corrected, references updated
Journal-ref: in "50 Years of Anderson Localization", ed. E. Abrahams (World
Scientific, Singapore, 2010), p. 473; reprinted in Int. J. Mod. Phys. B 24,
1727 (2010)
\\ ( http://arxiv.org/abs/1002.3696 , 168kb)
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arXiv:1005.3541 (*cross-listing*)
replaced with revised version Mon, 19 Jul 2010 20:30:30 GMT (87kb)
Title: Nonlinear resonant tunneling of Bose-Einstein condensates in tilted
optical lattices
Authors: K. Rapedius, C. Elsen, D. Witthaut, S. Wimberger, and H. J. Korsch
Categories: cond-mat.quant-gas quant-ph
Comments: Revised and enlarged version, including 1 additional figure
\\ ( http://arxiv.org/abs/1005.3541 , 87kb)
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\\
arXiv:0911.5443
replaced with revised version Tue, 20 Jul 2010 01:26:30 GMT (817kb)
Title: Conformal invariance, multifractality, and finite-size scaling at
Anderson localization transitions in two dimensions
Authors: Hideaki Obuse, Arvind R. Subramaniam, Akira Furusaki, Ilya A.
Gruzberg, Andreas W. W. Ludwig
Categories: cond-mat.dis-nn cond-mat.mes-hall cond-mat.stat-mech
Comments: 13 pages, 7 figures
Journal-ref: Phys. Rev. B 82, 035309 (2010)
DOI: 10.1103/PhysRevB.82.035309
\\ ( http://arxiv.org/abs/0911.5443 , 817kb)
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arXiv:0909.5615 (*cross-listing*)
replaced with revised version Tue, 20 Jul 2010 05:26:45 GMT (24kb)
Title: Pionic BEC--BCS crossover at finite isospin chemical potential
Authors: Masayuki Matsuzaki (Fukuoka Univ. of Education)
Categories: hep-ph cond-mat.quant-gas cond-mat.supr-con nucl-th
Comments: 17 pages, 3 figures, typos in eq.(6) and refs.[37] and [41] are
corrected, published in Phys. Rev. D
Journal-ref: Phys.Rev.D82:016005,2010
\\ ( http://arxiv.org/abs/0909.5615 , 24kb)
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arXiv:1004.2925
replaced with revised version Tue, 20 Jul 2010 18:45:32 GMT (10kb)
Title: Two super Tonks-Girardeau states of a trapped 1D spinor Fermi gas
Authors: M.D. Girardeau
Categories: cond-mat.quant-gas
Comments: 4 pages, no figures, revtex4. Revised version, published in Phys.
Rev. A 82, 011607(R) (2010)
\\ ( http://arxiv.org/abs/1004.2925 , 10kb)
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\\
arXiv:1004.1891
replaced with revised version Tue, 20 Jul 2010 21:44:12 GMT (2468kb)
Title: Dissipative Transport of a Bose-Einstein Condensate
Authors: D. Dries and S. E. Pollack and J. M. Hitchcock and R. G. Hulet
Categories: physics.atom-ph cond-mat.dis-nn cond-mat.quant-gas
Comments: 14 pages, 20 figures
\\ ( http://arxiv.org/abs/1004.1891 , 2468kb)
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arXiv:0804.0782
replaced with revised version Wed, 21 Jul 2010 03:31:28 GMT (106kb)
Title: Collective modes in asymmetric ultracold Fermi systems
Authors: Elena Gubankova, Massimo Mannarelli and Rishi Sharma
Categories: cond-mat.supr-con cond-mat.stat-mech hep-ph
Comments: 41 pages, 6 figures. Expanded introduction, improved figures,
conclusions unchanged. Version to match the published version
DOI: 10.1016/j.aop.2010.05.001
\\ ( http://arxiv.org/abs/0804.0782 , 106kb)
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arXiv:0709.1293
replaced with revised version Wed, 21 Jul 2010 03:55:37 GMT (166kb,D)
Title: Weakly interacting Bose gases below the critical temperature
Authors: E. Kovalchuk and R. Kobes
Categories: cond-mat.other
Comments: 15 pages, 9 figures, uses revtex4-1. Added references and
clarification of the nature and validity of the assumptions used
\\ ( http://arxiv.org/abs/0709.1293 , 166kb)
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\\
arXiv:1005.0463
replaced with revised version Wed, 21 Jul 2010 10:38:34 GMT (22kb)
Title: Mott Insulator to Superfluid transition in Bose-Bose mixtures in a
two-dimensional lattice
Authors: M. Guglielmino, V. Penna and B. Capogrosso-Sansone
Categories: cond-mat.quant-gas
Comments: 4 pages, 3 figures, accepted as PRA Rapid Communication
\\ ( http://arxiv.org/abs/1005.0463 , 22kb)
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arXiv:0908.2026
replaced with revised version Wed, 21 Jul 2010 13:35:09 GMT (214kb)
Title: Interacting trapped bosons yield fragmented condensate states in low
dimensions
Authors: Uwe R. Fischer and Philipp Bader
Categories: cond-mat.quant-gas
Comments: 9 pages of RevTex4, 4 figures; as published in Physical Review A
Journal-ref: Phys. Rev. A 82, 013607 (2010)
DOI: 10.1103/PhysRevA.82.013607
\\ ( http://arxiv.org/abs/0908.2026 , 214kb)
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arXiv:1003.3355
replaced with revised version Wed, 21 Jul 2010 19:07:49 GMT (770kb)
Title: Quantum Classical Correspondence for a non-Hermitian Bose-Hubbard Dimer
Authors: Eva-Maria Graefe, Hans J\"urgen Korsch, and Astrid Elisa Niederle
Categories: quant-ph cond-mat.quant-gas
Comments: 17 pages, 17 figures; bibliography updated, typos corrected,
published version
Journal-ref: Phys. Rev. A 82, 013629 (2010)
DOI: 10.1103/PhysRevA.82.013629
\\ ( http://arxiv.org/abs/1003.3355 , 770kb)
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arXiv:0912.0092
replaced with revised version Wed, 21 Jul 2010 23:27:18 GMT (835kb)
Title: Spin-Imbalance in a One-Dimensional Fermi Gas
Authors: Yean-an Liao, Ann Sophie C. Rittner, Tobias Paprotta, Wenhui Li,
Guthrie B. Partridge, Randall G. Hulet, Stefan K. Baur, Erich J. Mueller
Categories: physics.atom-ph cond-mat.quant-gas
Comments: 30 pages, 7 figures
\\ ( http://arxiv.org/abs/0912.0092 , 835kb)
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arXiv:1005.3239
replaced with revised version Thu, 22 Jul 2010 02:26:19 GMT (599kb)
Title: Competition between Normal Superfluidity and Larkin-Ovchinnikov Phases
of Polarized Fermi Gases in Elongated Traps
Authors: J.C. Pei, J. Dukelsky, W. Nazarewicz
Categories: cond-mat.quant-gas nucl-th
Comments: 4 pages, 4 figures; revision; accepted for publication in Phys.Rev.A
(Rapid Communication)
\\ ( http://arxiv.org/abs/1005.3239 , 599kb)
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arXiv:1007.0840 (*cross-listing*)
replaced with revised version Thu, 22 Jul 2010 09:35:26 GMT (1082kb)
Title: Entanglement spectrum: Identification of the transition from
vortex-liquid to vortex-lattice state in a weakly interacting rotating
Bose-Einstein condensate
Authors: Zhao Liu, Hong-Li Guo, Vlatko Vedral and Heng Fan
Categories: cond-mat.quant-gas quant-ph
Comments: 4 pages, 5 figures, comments are welcome. The title is changed.
Reference is added and reordered
\\ ( http://arxiv.org/abs/1007.0840 , 1082kb)
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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/
=========================================================================
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http://www.physics.uq.edu.au/people/mdavis/matts_arXiv/
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Received on Wed Oct 20 2010 - 09:28:34 EST
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