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

Date: Fri, 29 May 2009 08:12:09 +1000

Date: Fri, 29 May 2009 08:12:09 +1000

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

Dear subscribers,

Mike Garrett is the person to thank for helping edit this week's abstracts.

There are 34 new preprints and 15 replacements.

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arXiv:0904.2630

Date: Fri, 17 Apr 2009 04:32:53 GMT (34kb)

Title: Ginzburg-Landau theory of a trapped Fermi gas with a BEC-BCS crossover

Authors: Kun Huang, Zeng-Qiang Yu, Lan Yin

Categories: cond-mat.quant-gas cond-mat.supr-con

Comments: 16 pages, 2 figures, to be published in PRA

\\

The Ginzburg-Landau theory of a trapped Fermi gas with a BEC-BCS crossover is

derived by the path-integral method. In addition to the standard

Ginzburg-Landau equation, a second equation describing the total atom density

is obtained. These two coupled equations are necessary to describe both

homogeneous and inhomogeneous systems. The Ginzburg-Landau theory is valid near

the transition temperature $T_c$ on both sides of the crossover. In the

weakly-interacting BEC region, it is also accurate at zero temperature where

the Ginzburg-Landau equation can be mapped onto the Gross-Pitaevskii (GP)

equation. The applicability of GP equation at finite temperature is discussed.

On the BEC side, the fluctuation of the order parameter is studied and the

renormalization to the molecule coupling constant is obtained.

\\ ( http://arxiv.org/abs/0904.2630 , 34kb)

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arXiv:0904.2640

Date: Fri, 17 Apr 2009 06:29:08 GMT (171kb,D)

Title: Absence of Pressure-Driven Supersolid Flow at Low Frequency

Authors: Ann Sophie C. Rittner, Wonsuk Choi, Erich J. Mueller, and John D.

Reppy

Categories: cond-mat.other cond-mat.stat-mech

Comments: 4 pages, 5 figures

\\

We have conducted a low frequency (0.002 Hz) search for evidence of a

pressure-driven supersolid response, finding a null result. Our results set an

upper bound on the low frequency AC supersolid flow velocity of $3.3 \times

10^{-3}$ nm/s and on the AC displacement of 0.26 nm, a value roughly the size

of the $^4$He atom, and less than typical torsional oscillator amplitude of a

few nm. These findings, combined with related DC measurements by Day and

Beamish, suggest either that supersolid flow cannot be generated by pressure

gradients, or that supersolidity is a frequency dependent phenomenon that is

clearly evident at several hundred Hz, but undetectably small at mHz

frequencies.

\\ ( http://arxiv.org/abs/0904.2640 , 171kb)

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arXiv:0904.2729

Date: Fri, 17 Apr 2009 15:52:52 GMT (107kb)

Title: Dynamics and thermodynamics of systems with long-range interactions:

interpretation of the different functionals

Authors: Pierre-Henri Chavanis

Categories: cond-mat.stat-mech

Comments: Chapter of the volume "Dynamics and Thermodynamics of systems with

long range interactions: theory and experiments", A. Campa, A. Giansanti, G.

Morigi, F. Sylos Labini Eds., American Institute of Physics Conference

proceedings, 970 (2008)

Journal-ref: AIP Conf. Proc., 970, 39 (2008)

\\

We discuss the dynamics and thermodynamics of systems with weak long-range

interactions. Generically, these systems experience a violent collisionless

relaxation in the Vlasov regime leading to a (usually) non-Boltzmannian quasi

stationary state (QSS), followed by a slow collisional relaxation leading to

the Boltzmann statistical equilibrium state. These two regimes can be explained

by a kinetic theory, using an expansion of the BBGKY hierarchy in powers of

1/N, where N is the number of particles. We discuss the physical meaning of the

different functionals appearing in the analysis: the Boltzmann entropy, the

Lynden-Bell entropy, the "generalized" entropies arising in the reduced space

of coarse-grained distribution functions, the Tsallis entropy, the generalized

H-functions increasing during violent relaxation (not necessarily

monotonically) and the convex Casimir functionals used to settle the formal

nonlinear dynamical stability of steady states of the Vlasov equation. We show

the connection between the different variational problems associated with these

functionals. We also introduce a general class of nonlinear mean field

Fokker-Planck (NFP) equations that can be used as numerical algorithms to solve

these constrained optimization problems.

\\ ( http://arxiv.org/abs/0904.2729 , 107kb)

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arXiv:0904.2735

Date: Fri, 17 Apr 2009 16:03:41 GMT (590kb)

Title: Mesoscopic phases of dipolar ensembles with polar molecules and Rydberg

atoms

Authors: G. Pupillo, A. Micheli, M. Boninsegni, I. Lesanovsky, and P. Zoller

Categories: cond-mat.quant-gas cond-mat.stat-mech

Comments: 4+1 pages, 4 figs

\\

We discuss the realization of mesoscopic phases of dipolar gases relevant to

current experiments with cold polar molecules and Rydberg atoms confined to two

dimensions. We predict the existence of superfluid clusters, mesoscopic

supersolids, and crystals for a small number of trapped particles, with no

counterpart in the homogeneous situation. For certain strengths of the

dipole-dipole interactions, the stabilization of purely {\it non-classical

crystals} by quantum fluctuations is possible. We propose a magnification

scheme to detect the spatial structure of these crystalline phases.

\\ ( http://arxiv.org/abs/0904.2735 , 590kb)

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arXiv:0904.2616

Date: Fri, 17 Apr 2009 01:52:39 GMT (333kb)

Title: Strongly correlated quantum dynamics of multimode light coupled to a

two-level atom in a cavity

Authors: Tarun Kumar, Aranya B Bhattacherjee and ManMohan

Categories: quant-ph

\\

We study a composite multimode light-two-level atom system in a cavity. We

show that coupling of the two-level atom to multiple modes of the light

destroys the Mott phase of the composite system thus making the system less

useful platform for developing concepts in quantum information processing.

\\ ( http://arxiv.org/abs/0904.2616 , 333kb)

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arXiv:0904.2790

Date: Fri, 17 Apr 2009 22:05:16 GMT (431kb)

Title: Solitons and solitary vortices in "pancake"-shaped Bose-Einstein

condensates

Authors: Luca Salasnich and Boris A. Malomed

Categories: cond-mat.quant-gas cond-mat.other

Comments: Phys. Rev. A, in press

\\

We study fundamental and vortical solitons in disk-morphed Bose-Einstein

condensates (BECs) subject to strong confinement along the axial direction.

Starting from the three-dimensional (3D) Gross-Pitaevskii equation (GPE), we

proceed to an effective 2D nonpolynomial Schroeodinger equation (NPSE) derived

by means of the integration over the axial coordinate. Results produced by the

latter equation are in very good agreement with those obtained from the full 3D

GPE, including cases when the formal 2D equation with the cubic nonlinearity is

unreliable. The 2D NPSE is used to predict density profiles and dynamical

stability of repulsive and attractive BECs with zero and finite topological

charge in various planar trapping configurations, including the axisymmetric

harmonic confinement and 1D periodic potential. In particular, we find a stable

dynamical regime that was not reported before, viz., periodic splitting and

recombination of trapped vortices with topological charge 2 or 3 in the

self-attractive BEC.

\\ ( http://arxiv.org/abs/0904.2790 , 431kb)

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arXiv:0904.2881

Date: Sun, 19 Apr 2009 05:23:58 GMT (1455kb)

Title: A supercritical superfluid and vortex unbinding following a quantum

quench

Authors: L. Mathey, A. Polkovnikov

Categories: cond-mat.quant-gas

Comments: 6 pages, 6 figures

\\

The technological advances of trapping and manipulating ultra-cold atom

systems provide an opportunity to study many-body dynamics with unprecedented

clarity. Here we study the dynamics of the relative phase of a bilayer of

two-dimensional superfluids after the two superfluids have been decoupled,

using truncated Wigner approximation. We find that on short time scales the

relative phase shows `light cone' like thermalization and creates a metastable

superfluid state, which can be supercritical. On longer time scales this state

relaxes to a disordered state due to dynamical vortex unbinding. This scenario

of dynamically suppressed vortex proliferation constitutes an anti-Kibble-Zurek

effect. Our predictions are directly measurable in interference experiments, as

demonstrated in Ref. 1.

\\ ( http://arxiv.org/abs/0904.2881 , 1455kb)

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arXiv:0904.2927

Date: Sun, 19 Apr 2009 18:39:17 GMT (2173kb)

Title: Thermal effects in light scattering from ultracold bosons in an optical

lattice

Authors: Kazimierz {\L}akomy, Zbigniew Idziaszek, Marek Trippenbach

Categories: cond-mat.quant-gas quant-ph

\\

We study the scattering of a weak and far-detuned light from a system of

ultracold bosons in 1D and 3D optical lattices. We show the connection between

angular distributions of the scattered light and statistical properties of a

Bose gas in a periodic potential. The angular patterns are determined by the

Fourier transform of the second-order correlation function, and thus they can

be used to retrieve information on particle number fluctuations and

correlations. We consider superfluid and Mott insulator phases of the Bose gas

in a lattice, and we analyze in details how does the scattering depend on the

system dimensionality, temperature and atom-atom interactions.

\\ ( http://arxiv.org/abs/0904.2927 , 2173kb)

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arXiv:0904.2966

Date: Mon, 20 Apr 2009 08:15:56 GMT (42kb)

Title: Creation and detection of vortices in polariton condensates

Authors: Michiel Wouters and Vincenzo Savona

Categories: cond-mat.quant-gas

Comments: 4 pages, 4 figures

\\

We investigate theoretically the creation, persistence and detection of

quantized vortices in nonequilibrium polariton condensates within a stochastic

classical field model. The life time of the quantized vortices is shown to

increase with the spatial coherence and to depend on the geometry of the

condensate. The relation with superfluidity in conventional superfluids is

discussed. Three different ways to measure the vorticity of the polariton

condensate are proposed.

\\ ( http://arxiv.org/abs/0904.2966 , 42kb)

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arXiv:0904.3015

Date: Mon, 20 Apr 2009 12:10:07 GMT (118kb)

Title: Universal Spectra of Coherent Atoms in a Recurrent RandomWalk

Authors: R. Pugatch, O. Firstenberg, M. Shuker, N. Davidson

Categories: cond-mat.stat-mech

Comments: 5 pages, 3 figures

Journal-ref: Phys. Rev. Lett. vol. 102, p. 150602 (2009)

DOI: 10.1103/PhysRevLett.102.150602

\\

The probability of a random walker to return to its starting point in

dimensions one and two is unity, a theorem first proven by G. Polya. The

recurrence probability -- the probability to be found at the origin at a time

t, is a power law with a critical exponent d/2 in dimensions d=1,2. We report

an experiment that directly measures the Laplace transform of the recurrence

probability in one dimension using Electromagnetically Induced Transparency

(EIT) of coherent atoms diffusing in a vapor-cell filled with buffer gas. We

find a regime where the limiting form of the complex EIT spectrum is universal

and only depends on the effective dimensionality in which the random recurrence

takes place. In an effective one-dimensional diffusion setting, the measured

spectrum exhibits power law dependence over two decades in the frequency domain

with a critical exponent of 0.56 close to the expected value 0.5. Possible

extensions to more elaborate diffusion schemes are briefly discussed.

\\ ( http://arxiv.org/abs/0904.3015 , 118kb)

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arXiv:0904.3023

Date: Mon, 20 Apr 2009 14:53:34 GMT (20kb)

Title: Bulk viscosities for cold Fermi superfluids close to the unitary limit

Authors: Miguel Angel Escobedo, Massimo Mannarelli, Cristina Manuel

Categories: cond-mat.quant-gas cond-mat.other

Comments: 14 pages

\\

We compute the coefficients of bulk viscosity for a non-relativistic

superfluid corresponding to a fermionic system close to the unitarity limit. We

consider the low temperature regime assuming that the transport properties of

the system are dominated by phonons. To compute the coefficients of bulk

viscosity we use kinetic theory in the relaxation time approximation and the

low energy effective field theory of the corresponding system. We show that the

three independent bulk viscosity coefficients, $\zeta_1, \zeta_2, \zeta_3$,

associated with irreversible flows vanish for phonons with a linear dispersion

law. Considering a phonon dispersion law with a cubic term in momentum we find

that in the conformal limit $\zeta_1 = \zeta_2=0$, while $\zeta_3$ is non-zero.

Including a conformal breaking term which arises for a large but finite s-wave

scattering length, $a$, at the leading order in $1/a$ we obtain that $\zeta_1

\propto 1/a$ and $\zeta_2 \propto 1/a^2$.

\\ ( http://arxiv.org/abs/0904.3023 , 20kb)

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arXiv:0904.3031

Date: Mon, 20 Apr 2009 13:35:47 GMT (258kb)

Title: Non-extensive entropy of bosonic Fibonacci oscillators

Authors: Abdullah Algin

Categories: cond-mat.stat-mech cond-mat.quant-gas

Comments: 30 pages, 2 figures, accepted on JSTAT

Journal-ref: J. Stat. Mech.: Ther. Exp. (2009) P04007

DOI: 10.1088/1742-5468/2009/04/P04007

\\

We discuss possible connections between the thermostatistical properties of a

gas of the two-parameter deformed bosonic particles called Fibonacci

oscillators and the properties of the Tsallis thermostatistics. In this

framework, we particularly focus on a comparison of the non-extensive entropy

functions expressed by these two generalized theories. We also show that the

thermostatistics of the two-parameter deformed bosons can be studied by the

formalism of Fibonacci calculus, which generalizes the recently proposed

formalism by Lavagno and Narayana Swamy of q-calculus for the one-parameter

deformed boson gas. As an application, we briefly summarize some of the recent

results on the Bose-Einstein condensation phenomenon for the present

two-parameter generalized boson gas.

\\ ( http://arxiv.org/abs/0904.3031 , 258kb)

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arXiv:0904.3065

Date: Mon, 20 Apr 2009 16:00:38 GMT (451kb)

Title: Symmetry breaking in quantum systems: the case study of vortex

nucleation

Authors: D. Dagnino, N. Barberan, M. Lewenstein, and J. Dalibard

Categories: cond-mat.quant-gas

Comments: Accepted in Nature Physics

\\

Mean field (MF) methods constitute a very powerful tool for investigations of

weakly interacting many-body systems in many branches of physics. In articular

they describe with an excellent accuracy trapped Bose-Einstein condensates. A

generic, but difficult question concerns the relation between the symmetry

properties of the true many-body state and its MF approximation. We address

this question by considering vortex nucleation in a rotating Bose-Einstein

condensate (BEC). A slow sweep of the rotation frequency changes the state of

the system from being at rest to the one containing one vortex. Within the MF

framework, the jump in the symmetry occurs through a turbulent phase around a

certain critical frequency. The exact many-body ground state at the critical

frequency corresponds to a fragmented condensate with strong correlations and

entanglement. We believe that this constitutes a paradigm example of symmetry

breaking/change in the adiabatic evolution of quantum many-body systems.

\\ ( http://arxiv.org/abs/0904.3065 , 451kb)

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arXiv:0904.3075

Date: Mon, 20 Apr 2009 17:24:55 GMT (218kb)

Title: Exact solution of the Bose-Hubbard model on the Bethe lattice

Authors: Guilhem Semerjian, Marco Tarzia and Francesco Zamponi

Categories: cond-mat.quant-gas cond-mat.other

Comments: 27 pages, 16 figures

\\

The exact solution of a quantum Bethe lattice model in the thermodynamic

limit amounts to resolve a functional self-consistent equation. In this paper

we obtain this equation for the Bose-Hubbard model on the Bethe lattice, under

two equivalent forms. The first one, based on a coherent state path integral,

leads in the large connectivity limit to the mean field treatment of Fisher et

al. [Phys. Rev. B 40, 546 (1989)] at the leading order, and to the bosonic

Dynamical Mean Field Theory as a first correction, as recently derived by

Byczuk and Vollhardt [Phys. Rev. B 77, 235106 (2008)]. We obtain an alternative

form of the equation using the occupation number representation, which can be

easily solved with an arbitrary numerical precision, for any finite

connectivity. We thus compute the transition line between the superfluid and

Mott insulator phases of the model, along with thermodynamic observables and

the space and imaginary time dependence of correlation functions. The finite

connectivity of the Bethe lattice induces a richer physical content with

respect to its mean-field counterpart: a notion of distance between sites of

the lattice is preserved, and the bosons are still weakly mobile in the Mott

insulator phase. The Bethe lattice construction can be viewed as an

approximation to the finite dimensional version of the model. We show indeed a

quantitatively reasonable agreement between our predictions and the results of

Quantum Monte Carlo simulations in two and three dimensions.

\\ ( http://arxiv.org/abs/0904.3075 , 218kb)

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arXiv:0904.2415

Date: Wed, 15 Apr 2009 23:41:30 GMT (170kb)

Title: Soliton Dynamics in Linearly Coupled Discrete Nonlinear Schr\"odinger

Equations

Authors: A. Trombettoni, H.E. Nistazakis, Z. Rapti, D.J. Frantzeskakis, P.G.

Kevrekidis

Categories: nlin.PS cond-mat.stat-mech

Comments: to be published in Mathematics and Computers in Simulation,

proceedings of the fifth IMACS International Conference on Nonlinear

Evolution Equations and Wave Phenomena: Computation and Theory (Athens,

Georgia - April 2007)

\\

We study soliton dynamics in a system of two linearly coupled discrete

nonlinear Schr\"odinger equations, which describe the dynamics of a

two-component Bose gas, coupled by an electromagnetic field, and confined in a

strong optical lattice. When the nonlinear coupling strengths are equal, we use

a unitary transformation to remove the linear coupling terms, and show that the

existing soliton solutions oscillate from one species to the other. When the

nonlinear coupling strengths are different, the soliton dynamics is numerically

investigated and the findings are compared to the results of an effective

two-mode model. The case of two linearly coupled Ablowitz-Ladik equations is

also investigated.

\\ ( http://arxiv.org/abs/0904.2415 , 170kb)

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arXiv:0904.3048

Date: Mon, 20 Apr 2009 14:47:16 GMT (24kb)

Title: Quantum particles from classical statistics

Authors: C.Wetterich

Categories: quant-ph

Comments: 15 pages

\\

Quantum particles and classical particles are described in a common setting

of classical statistical physics. Both correspond to isolated subsystems of

ensembles describing the particle and its environment. The property of a

particle being "classical" or "quantum" ceases to be a basic conceptual

difference. The dynamics differs, however, between quantum and classical

particles. We describe location, motion and correlations of a quantum particle

in terms of observables in a classical statistical ensemble. We also construct

explicitly the quantum mechanical Hamiltonian and wave function for classical

particles. Besides conceptual advances, the treatment of classical and quantum

particles in a common formalism could lead to interesting cross-fertilization

between classical statistics and quantum mechanics.

\\ ( http://arxiv.org/abs/0904.3048 , 24kb)

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arXiv:0904.3059

Date: Mon, 20 Apr 2009 15:43:01 GMT (79kb)

Title: Cooling of a particle by coupling to its own reflection

Authors: Peter Horak, Andr\'e Xuereb, Tim Freegarde

Categories: quant-ph

Comments: 4 pages, 3 figures

\\

We identify and explore a cooling force resulting from the retarded dipole

interaction between an illuminated particle and its reflection. For a

one-dimensional example, we find cooling times of milliseconds and limiting

temperatures in the millikelvin range. The force, which may be considered the

prototype for cavity-mediated cooling, may also be enhanced by plasmon and

cavity resonances at the mirror.

\\ ( http://arxiv.org/abs/0904.3059 , 79kb)

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arXiv:0904.3097

Date: Mon, 20 Apr 2009 20:06:42 GMT (409kb)

Title: Composite Fermion Theory for Bosonic Atoms in Optical Lattices

Authors: Gunnar Moller and Nigel R. Cooper

Categories: cond-mat.mes-hall cond-mat.quant-gas

Comments: 4 pages, 2 figures

\\

We study the groundstates of cold atomic gases on rotating optical lattices,

as described by the Bose-Hubbard model in a uniform effective magnetic field.

Mapping the bosons to composite fermions leads to the prediction of quantum

Hall fluids that have no counterpart in the continuum. We construct trial

wavefunctions for these phases, and perform numerical tests of the predictions

of the composite fermion model. Our results establish the existence of strongly

correlated phases beyond those in the continuum limit, and provide evidence for

a wider scope of the composite fermion approach beyond its application to the

lowest Landau-level.

\\ ( http://arxiv.org/abs/0904.3097 , 409kb)

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arXiv:0904.3131

Date: Mon, 20 Apr 2009 22:43:00 GMT (226kb)

Title: Fortran programs for the time-dependent Gross-Pitaevskii equation in a

fully anisotropic trap

Authors: P. Muruganandam and S. K. Adhikari

Categories: cond-mat.quant-gas physics.comp-ph

Comments: 34 pages, 11 figures, 18 Fortran programs with respective output

files included in 18 compressed tar files

\\

We develop simple numerical algorithms for both stationary and non-stationary

solutions of the time-dependent Gross-Pitaevskii (GP) equation describing the

properties of Bose-Einstein condensates at ultra low temperatures. In

particular, we consider algorithms involving real and imaginary-time

propagation based on a split-step Crank-Nicholson method. In a

one-space-variable form of the GP equation we consider the one-dimensional

linear, two-dimensional circularly symmetric, and the three-dimensional

spherically-symmetric traps. In the two-space-variable form we consider the GP

equation in two-dimensional anisotropic and three-dimensional axially-symmetric

traps. The fully-anisotropic three-dimensional GP equation is also considered.

Numerical results for the chemical potential and root-mean-square size of

stationary states are reported using imaginary-time propagation programs for

all the cases and compared with previously obtained results. Also presented are

numerical results of non-stationary oscillation for different trap symmetries

using real-time propagation programs. A set of convenient working codes

developed in Fortran 77 are also provided for all these cases (twelve programs

in all). In the case of two or three space variables, {Fortran 90/95 versions

provide some simplification over the Fortran 77 programs}, and these programs

are also included (six programs in all).

\\ ( http://arxiv.org/abs/0904.3131 , 226kb)

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arXiv:0904.3179

Date: Tue, 21 Apr 2009 09:03:10 GMT (2448kb)

Title: Instability of superfluid Fermi gases induced by a roton-like density

mode in optical lattices

Authors: Yoshihiro Yunomae, Daisuke Yamamoto, Ippei Danshita, Nobuhiko Yokoshi,

Shunji Tsuchiya

Categories: cond-mat.quant-gas cond-mat.other

Comments: 32 pages, 11 figures

\\

We study the stability of superfluid Fermi gases in deep one-dimensional (1D)

and two-dimensional (2D) optical lattices in the BCS-BEC crossover at zero

temperature. Within the tight-binding attractive Hubbard model, we calculate

the spectrum of the low-energy Anderson-Bogoliubov (AB) mode as well as the

single-particle excitations in the presence of superfluid flow in order to

determine the critical velocities. To obtain the spectrum of the AB mode, we

calculate the density response function in the generalized random phase

approximation (GRPA) applying the Green's function formalism developed by

C\^ot\'e and Griffin to the Hubbard model. We find that the spectrum of the AB

mode is separated from the particle-hole continuum having the characteristic

roton-like minimum at short wavelength due to the strong charge-density-wave

(CDW) fluctuations. The energy of the roton-like minimum decreases with

increasing the lattice velocity and it reaches zero at the critical velocity

which is smaller than the pair-breaking velocity. This indicates that the

superfluid state is energetically unstable due to the spontaneous emission of

the short wavelength roton-like excitations of the AB mode instead due to

pair-breaking. We determine the critical velocities as functions of the

interaction strength across the BCS-BEC crossover regime.

\\ ( http://arxiv.org/abs/0904.3179 , 2448kb)

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arXiv:0904.3221

Date: Tue, 21 Apr 2009 10:51:15 GMT (148kb)

Title: Exact methods in analysis of nonequilibrium dynamics of integrable

models: application to the study of correlation functions in nonequilibrium

1D Bose gas

Authors: Vladimir Gritsev, Timofei Rostunov, Eugene Demler

Categories: cond-mat.quant-gas cond-mat.other

Comments: 26 pages, 7 figures

\\

In this paper we study nonequilibrium dynamics of one dimensional Bose gas

from the general perspective of dynamics of integrable systems. After outlining

and critically reviewing methods based on inverse scattering transform,

intertwining operators, q-deformed objects, and extended dynamical conformal

symmetry, we focus on the form-factor based approach. Motivated by possible

applications in nonlinear quantum optics and experiments with ultracold atoms,

we concentrate on the regime of strong repulsive interactions. We consider

dynamical evolution starting from two initial states: a condensate of particles

in a state with zero momentum and a condensate of particles in a gaussian

wavepacket in real space. Combining the form-factor approach with the method of

intertwining operator we develop a numerical procedure which allows explicit

summation over intermediate states and analysis of the time evolution of

non-local density-density correlation functions. In both cases we observe a

tendency toward formation of crystal-like correlations at intermediate time

scales.

\\ ( http://arxiv.org/abs/0904.3221 , 148kb)

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arXiv:0904.3314

Date: Tue, 21 Apr 2009 18:46:54 GMT (1683kb)

Title: Rapid production of $^{87}$Rb BECs in a combined magnetic and optical

potential

Authors: Y.-J. Lin, A. R. Perry, R. L. Compton, I. B. Spielman and J. V. Porto

Categories: cond-mat.quant-gas

\\

We describe an apparatus for quickly and simply producing $\Rb87$

Bose-Einstein condensates. It is based on a magnetic quadrupole trap and a red

detuned optical dipole trap. We collect atoms in a magneto-optical trap (MOT)

and then capture the atom in a magnetic quadrupole trap and force rf

evaporation. We then transfer the resulting cold, dense cloud into a spatially

mode-matched optical dipole trap by lowering the quadrupole field gradient to

below gravity. This technique combines the efficient capture of atoms from a

MOT into a magnetic trap with the rapid evaporation of optical dipole traps;

the approach is insensitive to the peak quadrupole gradient and the precise

trapping beam waist. Our system reliably produces a condensate with

$N\approx2\times10^6$ atoms every $16\second$.

\\ ( http://arxiv.org/abs/0904.3314 , 1683kb)

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arXiv:0904.2768 (*cross-listing*)

Date: Fri, 17 Apr 2009 19:26:12 GMT (288kb)

Title: The Bogoliubov/de Gennes system, the AKNS hierarchy, and nonlinear

quantum mechanical supersymmetry

Authors: Francisco Correa, Gerald V. Dunne and Mikhail S. Plyushchay

Categories: hep-th cond-mat.supr-con math-ph math.MP quant-ph

Comments: 25 pages, 4 figures

\\

We show that the Ginzburg-Landau expansion of the grand potential for the

Bogoliubov-de Gennes Hamiltonian is determined by the integrable nonlinear

equations of the AKNS hierarchy, and that this provides the natural

mathematical framework for a hidden nonlinear quantum mechanical supersymmetry

underlying the dynamics.

\\ ( http://arxiv.org/abs/0904.2768 , 288kb)

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arXiv:0904.3175

Date: Tue, 21 Apr 2009 07:09:33 GMT (1074kb)

Title: Cold and Ultracold Molecules: Science, Technology, and Applications

Authors: Lincoln D. Carr, David DeMille, Roman V. Krems, and Jun Ye

Categories: quant-ph

Comments: 82 pages, 9 figures, review article to appear in New Journal of

Physics Special Issue on Cold and Ultracold Molecules

\\

This article presents a review of the current state of the art in the

research field of cold and ultracold molecules. It serves as an introduction to

the Special Issue of the New Journal of Physics on Cold and Ultracold Molecules

and describes new prospects for fundamental research and technological

development. Cold and ultracold molecules may revolutionize physical chemistry

and few body physics, provide techniques for probing new states of quantum

matter, allow for precision measurements of both fundamental and applied

interest, and enable quantum simulations of condensed-matter phenomena.

Ultracold molecules offer promising applications such as new platforms for

quantum computing, precise control of molecular dynamics, nanolithography, and

Bose-enhanced chemistry. The discussion is based on recent experimental and

theoretical work and concludes with a summary of anticipated future directions

and open questions in this rapidly expanding research field.

\\ ( http://arxiv.org/abs/0904.3175 , 1074kb)

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arXiv:0904.3238

Date: Tue, 21 Apr 2009 12:45:51 GMT (20kb)

Title: Non-local quantum correlations and detection processes in QFT

Authors: Fabrizio Buscemi and Giuseppe Compagno

Categories: quant-ph

Comments: 23 pages

\\

Quantum detection processes in QFT must play a key role in the description of

quantum field correlations, such as the appearance of entanglement, and of

causal effects. We consider the detection in the case of a simple QFT model

with a suitable interaction to exact treatment, consisting of a quantum scalar

field coupled linearly to a classical scalar source. We then evaluate the

response function to the field quanta of two-level point-like quantum model

detectors, and analyze the effects of the approximation adopted in standard

detection theory. We show that the use of the RWA, that characterizes the

Glauber detection model, leads in the detector response to non-local terms

corresponding to an instantaneously spreading of source effects over the whole

space. Other detector models, obtained with non-standard or the no-application

of RWA, give instead local responses to field quanta, apart from source

independent vacuum contribution linked to preexisting correlations of

zero-point field.

\\ ( http://arxiv.org/abs/0904.3238 , 20kb)

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\\

arXiv:0904.3266

Date: Tue, 21 Apr 2009 15:06:40 GMT (1952kb)

Title: Enhancing an Atom Interferometer Area using Double-diffraction

Authors: Thomas L\'ev\`eque (SYRTE), A. Gauguet (SYRTE), Franck Michaud

(SYRTE), Franck Pereira Dos Santos (SYRTE), Arnaud Landragin (SYRTE)

Categories: physics.atom-ph

\\

In this paper we demonstrate a new scheme for Raman transitions which realize

a symmetric momentum-space splitting of $4 \hbar k$, deflecting the atomic

wave-packets into the same internal state. Combining the advantages of Raman

and Bragg diffraction, we achieve a three pulse state labelled interferometer,

intrinsically insensitive to the main systematics. This splitting scheme can be

extended to $4N \hbar k$ momentum transfer by a multipulse sequence and is

implemented on a $8 \hbar k$ interferometer. Measuring inertial phase shifts,

we demonstrate an area enhancement of a factor of 3.46 with respect to the

traditionally used geometry.

\\ ( http://arxiv.org/abs/0904.3266 , 1952kb)

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\\

arXiv:0904.3376

Date: Wed, 22 Apr 2009 02:50:40 GMT (247kb)

Title: Stability and chaotic behavior of Bose-Einstein condensates in optical

lattices with two- and three-body interactions

Authors: Yan Chen, Li-Bin Fu, Ke-Zhi Zhang, and Yong Chen

Categories: cond-mat.quant-gas

Comments: 13 pages, 6 figures

\\

The stability and chaotic behavior of Bose-Einstein condensates with two- and

three-atoms interactions in optical lattices are discussed with analytically

and numerically methods. It is demonstrated that the steady-state relative

population will appear tuning-fork bifurcation when the system parameters are

changed to certain critical values. In particular, the existence of three-body

interaction not only transform the bifurcation point of the system but also

affect greatly on the self-trapping behavior of the system associated with the

critically stable steady-state solution. In addition, we also investigated the

influence of the initial conditions, three-body interaction and the energy bias

on the macroscopic quantum self-trapping. Finally, by applying the periodic

modulation on the energy bias, we find that the relative population oscillation

can exhibit a process from order to chaos, through a series of period-doubling

bifurcations.

\\ ( http://arxiv.org/abs/0904.3376 , 247kb)

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\\

arXiv:0904.3440

Date: Wed, 22 Apr 2009 12:06:08 GMT (222kb,D)

Title: Numerical method for evolving the dipolar projected Gross-Pitaevskii

equation

Authors: P. B. Blakie, C. Ticknor, A. S. Bradley, A. M. Martin, M. J. Davis,

and Y. Kawaguchi

Categories: cond-mat.quant-gas cond-mat.stat-mech

Comments: 16 pages, 6 figures

\\

We describe a method for evolving the projected Gross-Pitaevskii equation

(PGPE) for an interacting Bose gas in a harmonic oscillator potential, with the

inclusion of a long-range dipolar interaction. The central difficulty in

solving this equation is the requirement that the field is restricted to a

small set of prescribed modes that constitute the low energy c-field region of

the system. We present a scheme, using a Hermite-polynomial based spectral

representation, that precisely implements this mode restriction and allows an

efficient and accurate solution of the dipolar PGPE. We introduce a set of

auxiliary oscillator states to perform a Fourier transform necessary to

evaluate the dipolar interaction in reciprocal space. We extensively

characterize the accuracy of our approach, and derive Ehrenfest equations for

the evolution of the angular momentum.

\\ ( http://arxiv.org/abs/0904.3440 , 222kb)

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\\

arXiv:0904.3477

Date: Wed, 22 Apr 2009 15:26:53 GMT (558kb,D)

Title: Feshbach resonant scattering of three fermions in one-dimensional wells

Authors: T. Duric, A. F. Ho, and D .K. K. Lee

Categories: cond-mat.quant-gas

Comments: 10 pages, 5 figures

\\

We study the weak-tunnelling limit for a system of cold 40K atoms trapped in

a one-dimensional optical lattice close to an s-wave Feshbach resonance. We

calculate the local spectrum for three atoms at one site of the lattice within

a two-channel model. Our results indicate that, for this one-dimensional

system, one- and two-channel models will differ close to the Feshbach

resonance, although the two theories would converge in the limit of strong

Feshbach coupling. We also find level crossings in the low-energy spectrum of a

single well with three atoms that may lead to quantum phase transition for an

optical lattice of many wells. We discuss the stability of the system to a

phase with non-uniform density.

\\ ( http://arxiv.org/abs/0904.3477 , 558kb)

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\\

arXiv:0904.3107 (*cross-listing*)

Date: Tue, 21 Apr 2009 01:15:58 GMT (435kb)

Title: Nearly Perfect Fluidity: From Cold Atomic Gases to Hot Quark Gluon

Plasmas

Authors: Thomas Schaefer (North Carolina State University), Derek Teaney (SUNY

Stony Brook and Riken-BNL)

Categories: hep-ph cond-mat.quant-gas hep-lat hep-th nucl-th

Comments: 69 pages, 9 figures, review article

\\

Quantum uncertainty suggests a lower bound on the internal friction -- shear

viscosity -- of a fluid. The shear viscosity of a nearly perfect fluid

approaches this bound. A measure of fluidity is provided by the ratio of shear

viscosity eta to entropy density s. In this review we summarize theoretical and

experimental information on the properties of the three main classes of quantum

fluids that are known to have values of eta/s that are smaller than hbar/k_B,

where hbar is Planck's constant and k_B is Boltzmann's constant. These fluids

are strongly coupled Bose fluids, in particular liquid helium, strongly

correlated ultracold Fermi gases, and the quark gluon plasma. We discuss the

main theoretical approaches to transport properties of these fluids: kinetic

theory, numerical simulations based on linear response theory, and holographic

dualities. We also summarize the experimental situation, in particular with

regard to the observation of hydrodynamic behavior in ultracold Fermi gases and

the quark gluon plasma.

\\ ( http://arxiv.org/abs/0904.3107 , 435kb)

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\\

arXiv:0904.3511

Date: Wed, 22 Apr 2009 17:32:19 GMT (230kb)

Title: Capture into Rydberg states and momentum distributions of ionized

electrons

Authors: N.I. Shvetsov-Shilovski (1), S.P. Goreslavski (1), S.V. Popruzhenko

(1), and W. Becker (2) ((1) Moscow State Engineering Physics Institute,

Moscow, Russia (2) Max-Born-Institut, Berlin, Germany)

Categories: physics.atom-ph physics.atm-clus

Comments: 9 pages, 8 figures in one zip-archive

\\

The yield of neutral excited atoms and low-energy photoelectrons generated by

the electron dynamics in the combined Coulomb and laser field after tunneling

is investigated. We present results of Monte-Carlo simulations built on the

two-step semiclassical model, as well as analytic estimates and scaling

relations for the population trapping into the Rydberg states. It is shown that

mainly those electrons are captured into bound states of the neutral atom that

due to their initial conditions (i) have moderate drift momentum imparted by

the laser field and (ii) avoid strong interaction ("hard" collision) with the

ion. In addition, it is demonstrated that the channel of capture, when

accounted for in semiclassical calculations, has a pronounced effect on the

momentum distribution of electrons with small positive energy. For the

parameters that we investigated its presence leads to a dip at zero momentum in

the longitudinal momentum distribution of the ionized electrons.

\\ ( http://arxiv.org/abs/0904.3511 , 230kb)

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\\

arXiv:0904.3643

Date: Thu, 23 Apr 2009 10:12:21 GMT (29kb)

Title: The superfluid-Bose glass transition in a 1-D weakly interacting Bose

gas

Authors: Luca Fontanesi, Michiel Wouters, Vincenzo Savona

Categories: cond-mat.quant-gas cond-mat.dis-nn

Comments: 4 pages, 4 figures

\\

We study the one-dimensional Bose gas in spatially correlated disorder at

T=0, using an extended density-phase Bogoliubov method. The decay of the

one-body density matrix is analyzed and particular attention is paid to the

behavior of the low-energy Bogoliubov excitations across the phase boundary. We

have observed that the transition to the Bose glass phase is marked by a

divergence in the density of states together with a 1/E behaviour of the

localization length of the Bogoliubov modes. Finally we draw the phase diagram

of the superfluid-insulator transition in the limit of small interaction

strength.

\\ ( http://arxiv.org/abs/0904.3643 , 29kb)

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\\

arXiv:0904.3738

Date: Thu, 23 Apr 2009 19:24:02 GMT (458kb)

Title: p-wave resonant Bose gas: a "spinor supersolid"

Authors: Leo Radzihovsky, Sungsoo Choi

Categories: cond-mat.quant-gas cond-mat.other

Comments: 4 pages, 1 figure

\\

We show that a degenerate gas of two-species bosonic atoms interacting

through a p-wave Feshbach resonance (as e.g., realized in a 85Rb-87Rb mixture)

exhibits an atomic-molecular supersolid phase (AMSF), sandwiched by a molecular

p-wave (orbital spinor) superfluid and by an s-wave atomic superfluid at large

negative and positive detunings, respectively. The magnetic field can be used

to tune the modulation wavevector of the AMSF state, as well as to drive

quantum phase transitions in this rich system.

\\ ( http://arxiv.org/abs/0904.3738 , 458kb)

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\\

arXiv:0904.3617

Date: Thu, 23 Apr 2009 08:08:05 GMT (595kb,D)

Title: Entanglement assisted spin-wave atom interferometer

Authors: Yu-Ao Chen, Xiao-Hui Bao, Zhen-Sheng Yuan, Shuai Chen, Bo Zhao,

Jian-Wei Pan

Categories: quant-ph

Comments: 6 pages, 5 figures (including appendix)

\\

We report the observation of phase-super resolution in a motion-sensitive

spin-wave (SW) atom interferometer utilizing a NOON-type entanged state. The SW

interferometer is implemented by generating a superposition of two SWs and

observing the interference between them, where the interference fringe is

sensitive to the atomic collective motion. By heralded generation of a second

order NOON state in the SW interferometer, we clearly observe the interference

pattern with phase super-resolution. The demonstrated SW interferometer can in

principle be scaled up to highly entangled quantum state, and thus is of

fundamental importance to implement quantum-enhanced-measurement.

\\ ( http://arxiv.org/abs/0904.3617 , 595kb)

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The replacements:

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\\

arXiv:0812.1782

replaced with revised version Fri, 17 Apr 2009 14:53:39 GMT (211kb)

Title: Relativistic BCS-BEC crossover of a two-species Fermi gas with number

density asymmetry at zero temperature

Authors: Hao Guo, Chih-Chun Chien and Yan He

Categories: hep-ph cond-mat.other

Comments: 18 pages, 6 figures

Journal-ref: Nuclear Physics A 823, 83 (2009)

\\ ( http://arxiv.org/abs/0812.1782 , 211kb)

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\\

arXiv:0903.1639

replaced with revised version Thu, 16 Apr 2009 20:12:40 GMT (488kb)

Title: Angle resolved photon spectrum and quasiparticle excitation spectrum in

an exciton superfluid

Authors: Jinwu Ye, T. Shi and Longhua Jiang

Categories: cond-mat.mes-hall cond-mat.mtrl-sci physics.atom-ph physics.optics

Comments: 4+ \epsilon pages, 2 color figures, REVTEX4

Report-no: NSF-KITP 09-42

\\ ( http://arxiv.org/abs/0903.1639 , 488kb)

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\\

arXiv:0903.2254

replaced with revised version Mon, 20 Apr 2009 14:58:21 GMT (498kb,D)

Title: Emergent superfluid crystals, frustration, and topologically defected

states in multimode cavity QED

Authors: Sarang Gopalakrishnan, Benjamin L. Lev, and Paul M. Goldbart

Categories: cond-mat.other quant-ph

Comments: 8 pages, 3 figures; added references

\\ ( http://arxiv.org/abs/0903.2254 , 498kb)

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\\

arXiv:0904.2399

replaced with revised version Sun, 19 Apr 2009 22:15:31 GMT (118kb)

Title: Bose-Einstein and Fermi-Dirac distributions in nonextensive quantum

statistics: An exact approach

Authors: Hideo Hasegawa (Tokyo Gakugei Univ.)

Categories: cond-mat.stat-mech cond-mat.other

Comments: 23 pages, 11 figures; revised the text

\\ ( http://arxiv.org/abs/0904.2399 , 118kb)

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\\

arXiv:0901.3268

replaced with revised version Sat, 18 Apr 2009 07:31:38 GMT (45kb)

Title: Two-level atom at finite temperature

Authors: Tomasz Sowinski

Categories: quant-ph

Comments: 12 pages

\\ ( http://arxiv.org/abs/0901.3268 , 45kb)

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\\

arXiv:0903.4401

replaced with revised version Mon, 20 Apr 2009 14:00:48 GMT (303kb)

Title: Photoassociation and coherent transient dynamics in the interaction of

ultracold rubidium atoms with shaped femtosecond pulses - II. Theory

Authors: Andrea Merli, Frauke Eimer, Fabian Weise, Albrecht Lindinger, Wenzel

Salzmann, Terry Mullins, Simone Gotz, Roland Wester, Matthias Weidemuller,

Ruzin Aganoglu, Christiane P. Koch

Categories: physics.atom-ph physics.chem-ph

\\ ( http://arxiv.org/abs/0903.4401 , 303kb)

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\\

arXiv:0809.0350

replaced with revised version Tue, 21 Apr 2009 07:14:25 GMT (927kb)

Title: Stability of superfluid Fermi gases in optical lattices

Authors: Yoshihiro Yunomae, Ippei Danshita, Daisuke Yamamoto, Nobuhiko Yokoshi,

and Shunji Tsuchiya

Categories: cond-mat.other

Comments: 4 pages, 4 figures, conference proceeding for ISQM-TOKYO'08

\\ ( http://arxiv.org/abs/0809.0350 , 927kb)

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\\

arXiv:0901.2295

replaced with revised version Tue, 21 Apr 2009 10:12:42 GMT (1414kb)

Title: Photonic spectrum of bichromatic optical lattices

Authors: Stefan Rist, Patrizia Vignolo, Giovanna Morigi

Categories: quant-ph cond-mat.other

Comments: 10 pages, 10 figures, to appear in PRA

\\ ( http://arxiv.org/abs/0901.2295 , 1414kb)

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\\

arXiv:0901.3979

replaced with revised version Tue, 21 Apr 2009 14:28:20 GMT (2032kb,D)

Title: Intensity-field correlation of single-atom resonance fluorescence

Authors: S. Gerber, D. Rotter, L. Slodicka, J. Eschner, H. J. Carmichael, and

R. Blatt

Categories: quant-ph

Comments: 4 pages, 4 figures, accepted in PRL

\\ ( http://arxiv.org/abs/0901.3979 , 2032kb)

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\\

arXiv:0902.4818

replaced with revised version Wed, 22 Apr 2009 15:31:14 GMT (12kb)

Title: Hyperfine frequency shift in two-dimensional atomic hydrogen

Authors: A.I.Safonov, I.I.Safonova and I.S.Yasnikov

Categories: quant-ph cond-mat.soft

Comments: 4 pages, no figures

\\ ( http://arxiv.org/abs/0902.4818 , 12kb)

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\\

arXiv:0904.3015

replaced with revised version Wed, 22 Apr 2009 08:04:36 GMT (118kb)

Title: Universal Spectra of Coherent Atoms in a Recurrent Random Walk

Authors: R. Pugatch, O. Firstenberg, M. Shuker, N. Davidson

Categories: cond-mat.stat-mech

Comments: 5 pages, 3 figures

Journal-ref: Phys. Rev. Lett. vol. 102, p. 150602 (2009)

DOI: 10.1103/PhysRevLett.102.150602

\\ ( http://arxiv.org/abs/0904.3015 , 118kb)

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\\

arXiv:0806.2960

replaced with revised version Thu, 23 Apr 2009 12:37:50 GMT (30kb)

Title: Systematic Semiclassical Expansion for Harmonically Trapped Ideal Bose

Gases

Authors: Ben Kl\"under and Axel Pelster

Categories: cond-mat.stat-mech

Comments: Author Information under

http://www.theo-phys.uni-essen.de/tp/ags/pelster_dir

Journal-ref: European Physical Journal B 68, 457-465 (2009)

\\ ( http://arxiv.org/abs/0806.2960 , 30kb)

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\\

arXiv:0901.4008

replaced with revised version Thu, 23 Apr 2009 18:01:05 GMT (51kb)

Title: Cumulative identical spin rotation effects in collisionless trapped

atomic gases

Authors: F. Piechon, J.N. Fuchs, and F. Laloe

Categories: physics.atom-ph cond-mat.other

Comments: 4 pages, 2 figures; v2: comparison to experimental data added

\\ ( http://arxiv.org/abs/0901.4008 , 51kb)

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\\

arXiv:0902.4653

replaced with revised version Wed, 22 Apr 2009 22:51:48 GMT (402kb)

Title: FFLO vs Bose-Fermi mixture in polarized 1D Fermi gas on a Feshbach

resonance: a 3-body study

Authors: Stefan K. Baur, John Shumway, Erich J. Mueller

Categories: cond-mat.supr-con

Comments: 4 pages, 3 figures

\\ ( http://arxiv.org/abs/0902.4653 , 402kb)

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\\

arXiv:0903.0884

replaced with revised version Thu, 23 Apr 2009 15:28:38 GMT (169kb)

Title: Prediction of Feshbach resonances from three input parameters

Authors: Thomas M. Hanna, Eite Tiesinga, Paul S. Julienne

Categories: cond-mat.other

Comments: 5 pages, 2 figures, revised version

\\ ( http://arxiv.org/abs/0903.0884 , 169kb)

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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/ ========================================================================= Legal stuff: Unless stated otherwise, this e-mail represents only the views of the sender and not the views of the University of Queensland =========================================================================Received on Fri May 29 2009 - 09:16:09 EST

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