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

Date: Sun, 14 Oct 2007 13:06:52 +1000 (EST)

Date: Sun, 14 Oct 2007 13:06:52 +1000 (EST)

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

Almost caught up... 26 new preprints and 11 replacments this week.

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arXiv:0709.3381

Date: Fri, 21 Sep 2007 12:26:12 GMT (34kb,D)

Title: Generalized ABCD propagation for interacting atomic clouds

Authors: F. Impens and Ch. J. Bord\'e

Categories: cond-mat.soft cond-mat.other

Comments: 10 pages, 2 figures

\\

We present a generalization of the atom optics ABCD formalism which

encapsulates atomic interactions in the aberationless approximation.

Interactions are modelled through an effective atom-optical lens term

determined perturbatively from the linear evolution. We apply this approach to

the determination of interaction effects in a free-falling cloud and to the

derivation of a stability condition for a matter-wave cavity.

\\ ( http://arxiv.org/abs/0709.3381 , 34kb)

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arXiv:0709.3392

Date: Fri, 21 Sep 2007 10:26:52 GMT (14kb)

Title: Optimally localized Wannier functions for quasi one-dimensional

nonperiodic insulators

Authors: H. D. Cornean, A. Nenciu and G. Nenciu

Categories: cond-mat.other

Comments: 16 pages, submitted

\\

It is proved that for general, not necessarily periodic quasi one dimensional

systems, the band position operator corresponding to an isolated part of the

energy spectrum has discrete spectrum and its eigenfunctions have the same

spatial localization as the corresponding spectral projection.

As a consequence, an eigenbasis of the band position operator provides a

basis of optimally localized (generalized) Wannier functions for quasi one

dimensional systems. If the system has some translation symmetries (e.g. usual

translations, screw transformations), they are "inherited" by the Wannier

basis.

\\ ( http://arxiv.org/abs/0709.3392 , 14kb)

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arXiv:0709.3310

Date: Thu, 20 Sep 2007 21:59:38 GMT (575kb)

Title: Final Report on ECCS/NSF Workshop on Quantum, Molecular and High

Performance Modeling and Simulation for Devices and Systems (QMHP)

Authors: Jonathan P. Dowling, Gerhard Klimeck

Categories: quant-ph

Comments: 42 pages, NSF Workshop on Quantum Molecular and High Performance

Modeling and Simulations for Devices and Systems (QMHP), 16-17 April 2007,

Arlington VA

\\

The National Science Foundation has identified a new thrust area in Quantum,

Molecular and High Performance Modeling and Simulation for Devices and Systems

(QMHP) in its core program. The main purpose of this thrust area is to capture

scientific opportunities that result from new fundamental cross-cutting

research involving three core research communities: (1) experts in modeling and

simulation of electronic devices and systems; (2) high performance computing

relevant to devices and systems; and (3) the quantum many-body principles

relevant to devices and systems. ECCS is especially interested in learning how

work in these areas could enable whole new classes of systems or devices,

beyond what is already under development in existing mainstream research. The

workshop helped identify technical areas that will enable fundamental

breakthroughs in the future. Modeling and simulation in the electronics and

optoelectronics areas, in general, have already resulted in important

fundamental scientific understanding and advances in design and development of

devices and systems. With the increasing emphasis on the next generation of

devices and systems at the nano, micro, and macro scales and the

interdisciplinary nature of the research, it is imperative that we explore new

mathematical models and simulation techniques. This workshop report provides a

better understanding of unmet emerging new opportunities to improve modeling,

simulation and design techniques for hybrid devices and systems. The purpose

the QMHP workshop was to define the field and strengthen the focus of the

thrust. The ultimate goal of the workshop was to produce a final report (this

document) that will be posted on the web so that the NSF can use it to guide

reviewers and researchers in this field.

\\ ( http://arxiv.org/abs/0709.3310 , 575kb)

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arXiv:0709.3335

Date: Fri, 21 Sep 2007 14:23:09 GMT (504kb)

Title: The quest for three-color entanglement: experimental investigation of

new multipartite quantum correlations

Authors: K. N. Cassemiro, A. S. Villar, M. Martinelli, and P. Nussenzveig

Categories: quant-ph

Comments: 10 pages, 5 figures, submitted to Opt. Express

\\

We experimentally investigate quadrature correlations between pump, signal,

and idler fields in an above-threshold optical parametric oscillator. We

observe new quantum correlations among the pump and signal or idler beams, as

well as among the pump and a combined quadrature of signal and idler beams. A

further investigation of unforeseen classical noise observed in this system is

presented, which hinders the observation of the recently predicted tripartite

entanglement. In spite of this noise, current results approach the limit

required to demonstrate three-color entanglement.

\\ ( http://arxiv.org/abs/0709.3335 , 504kb)

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arXiv:0709.3463

Date: Fri, 21 Sep 2007 15:32:52 GMT (113kb,D)

Title: Quantum Ratchets for Quantum Communication with Optical Superlattices

Authors: Oriol Romero-Isart and Juan Jose Garcia-Ripoll

Categories: quant-ph

Comments: 9 pages, 5 figures

\\

We propose to use a quantum ratchet to transport quantum information in a

chain of atoms trapped in an optical superlattice. The quantum ratchet is

created by a continuous modulation of the optical superlattice which is

periodic in time and in space. Though there is zero average force acting on the

atoms, we show that indeed the ratchet effect permits atoms on even and odd

sites to move along opposite directions. By loading the optical lattice with

two-level bosonic atoms, this scheme permits to perfectly transport a qubit or

entangled state imprinted in one or more atoms to any desired position in the

lattice. From the quantum computation point of view, the transport is achieved

by a smooth concatenation of perfect swap gates. We analyze setups with

noninteracting and interacting particles and in the latter case we use the

tools of optimal control to design optimal modulations. We also discuss the

feasibility of this method in current experiments.

\\ ( http://arxiv.org/abs/0709.3463 , 113kb)

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arXiv:0709.3331

Date: Fri, 21 Sep 2007 00:16:52 GMT (168kb)

Title: Parallel TREE code for two-component ultracold plasma analysis

Authors: Byoungseon Jeon, Joel D. Kress, Lee A. Collins and Niels

Gr{\o}nbech-Jensen

Categories: physics.comp-ph physics.plasm-ph

\\

The TREE method has been widely used for long-range interaction {\it N}-body

problems. We have developed a parallel TREE code for two-component classical

plasmas with open boundary conditions and highly non-uniform charge

distributions. The program efficiently handles millions of particles evolved

over long relaxation times requiring millions of time steps. Appropriate domain

decomposition and dynamic data management were employed, and large-scale

parallel processing was achieved using an intermediate level of granularity of

domain decomposition and ghost TREE communication. Even though the

computational load is not fully distributed in fine grains, high parallel

efficiency was achieved for ultracold plasma systems of charged particles. As

an application, we performed simulations of an ultracold neutral plasma with a

half million particles and a half million time steps. For the long temporal

trajectories of relaxation between heavy ions and light electrons, large

configurations of ultracold plasmas can now be investigated, which was not

possible in past studies.

\\ ( http://arxiv.org/abs/0709.3331 , 168kb)

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arXiv:0709.3740

Date: Mon, 24 Sep 2007 12:07:07 GMT (497kb)

Title: Staggered Vortex Superfluid of Ultracold Bosons in an Optical Lattice

Authors: Lih-King Lim, C. Morais Smith, Andreas Hemmerich

Categories: cond-mat.supr-con cond-mat.other

Comments: 4 pages, 3 figures

\\

We show that the dynamics of an ultracold bosonic gas loaded into a

two-dimensional square optical lattice with anisotropic and time-dependent

hopping terms can be described by a Bose-Hubbard model with an effective

staggered magnetic field. Besides the uniform superfluid and Mott insulating

phases, the zero-temperature phase diagram exhibits a novel kind of superfluid

phase, characterized by a quantized staggered rotational flux. This superfluid

condenses at finite momentum, a feature known from

Fulde-Ferrel-Larkin-Ovchinnikov phases of paired fermions.

\\ ( http://arxiv.org/abs/0709.3740 , 497kb)

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arXiv:0709.3768

Date: Mon, 24 Sep 2007 14:12:07 GMT (13kb)

Title: Thermalisation by a boson bath in a pure state

Authors: S. Camalet

Categories: cond-mat.mes-hall

\\

We consider a quantum system weakly coupled to a large heat bath of harmonic

oscillators. It is well known that such a boson bath initially at thermal

equilibrium thermalises the system. We show that assuming a priori an

equilibrium state is not necessary to obtain the thermalisation of the system.

We determine the complete Schr\"odinger time evolution of the subsystem of

interest for an initial pure product state of the composite system consisting

of the considered system and the bath. We find that the system relaxes into

canonical equilibrium for almost all initial pure bath states of

macroscopically well-defined energy. The temperature of the system asymptotic

thermal state is determined by the energy of the initial bath state as the

corresponding microcanonical temperature. Moreover, the time evolution of the

system is identical to the one obtained assuming that the boson bath is

initially at thermal equilibrium with this temperature. A significant part of

our approach is applicable to other baths and we identify the bath features

which are requisite for the thermalisation studied.

\\ ( http://arxiv.org/abs/0709.3768 , 13kb)

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arXiv:0707.2539

Date: Tue, 17 Jul 2007 15:15:12 GMT (100kb)

Title: Three-dimensional Monte Carlo simulations of the quantum linear

Boltzmann equation

Authors: Heinz-Peter Breuer and Bassano Vacchini

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

Comments: 11 pages, revtex, 11 figures

Journal-ref: Phys. Rev. E 76 (2007) 036706

DOI: 10.1103/PhysRevE.76.036706

\\

Recently the general form of a translation-covariant quantum Boltzmann

equation has been derived which describes the dynamics of a tracer particle in

a quantum gas. We develop a stochastic wave function algorithm that enables

full three-dimensional Monte Carlo simulations of this equation. The simulation

method is used to study the approach to equilibrium for various scattering

cross sections and to determine dynamical deviations from Gaussian statistics

through an investigation of higher-order cumulants. Moreover, we examine the

loss of coherence of superpositions of momentum eigenstates and determine the

corresponding decoherence time scales to quantify the transition from quantum

to classical behavior of the state of the test particle.

\\ ( http://arxiv.org/abs/0707.2539 , 100kb)

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arXiv:0709.3780

Date: Mon, 24 Sep 2007 18:03:10 GMT (259kb)

Title: Order parameter for the dynamical phase transition in Bose-Einstein

condensates with topological modes

Authors: E. R. F. Ramos, L. Sanz, V.I. Yukalov and V. S. Bagnato

Categories: quant-ph

Journal-ref: Phys. Rev. A 76, 033608 (2007)

DOI: 10.1103/PhysRevA.76.033608

\\

In a trapped Bose-Einstein condensate, subject to the action of an

alternating external field, coherent topological modes can be resonantly

excited. Depending on the amplitude of the external field and detuning

parameter, there are two principally different regimes of motion, with mode

locking and without it. The change of the dynamic regime corresponds to a

dynamic phase transition. This transition can be characterized by an effective

order parameter defined as the difference between fractional mode populations

averaged over the temporal period of oscillations. The behavior of this order

parameter, as a function of detuning, pumping amplitude, and atomic

interactions is carefully analyzed. A special attention is payed to numerical

calculations for the realistic case of a quadrupole exciting field and the

system parameters accessible in current experiments.

\\ ( http://arxiv.org/abs/0709.3780 , 259kb)

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arXiv:0709.3842

Date: Mon, 24 Sep 2007 21:02:32 GMT (27kb)

Title: A nonlinear Ramsey interferometer operating beyond the Heisenberg limit

Authors: S. Choi and B. Sundaram

Categories: cond-mat.other

Comments: 4 figures. Submitted for publication

\\

We show that a dynamically evolving two-mode Bose-Einstein condensate (TBEC)

with an adiabatic, time-varying Raman coupling maps exactly onto a nonlinear

Ramsey interferometer that includes a nonlinear medium. Assuming a realistic

quantum state for the TBEC, namely the SU(2) coherent spin state, we find that

the measurement uncertainty of the ``path-difference'' phase shift scales as

the standard quantum limit (1/N^{1/2}) where N is the number of atoms, while

that for the interatomic scattering strength scales as 1/N^{7/5}, overcoming

the Heisenberg limit of 1/N.

\\ ( http://arxiv.org/abs/0709.3842 , 27kb)

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arXiv:0709.3888

Date: Tue, 25 Sep 2007 08:01:21 GMT (219kb,D)

Title: Fluctuation Theorems

Authors: E.M. Sevick, R. Prabhakar, Stephen R. Williams and Debra J. Searles

Categories: cond-mat.stat-mech

Comments: A review, submitted to Annual Reviews in Physical Chemistry, July

2007

\\

Fluctuation theorems, which have been developed over the past 15 years, have

resulted in fundamental breakthroughs in our understanding of how

irreversibility emerges from reversible dynamics, and have provided new

statistical mechanical relationships for free energy changes. They describe the

statistical fluctuations in time-averaged properties of many-particle systems

such as fluids driven to nonequilibrium states, and provide some of the very

few analytical expressions that describe nonequilibrium states. Quantitative

predictions on fluctuations in small systems that are monitored over short

periods can also be made, and therefore the fluctuation theorems allow

thermodynamic concepts to be extended to apply to finite systems. For this

reason, fluctuation theorems are anticipated to play an important role in the

design of nanotechnological devices and in understanding biological processes.

These theorems, their physical significance and results for experimental and

model systems are discussed.

\\ ( http://arxiv.org/abs/0709.3888 , 219kb)

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arXiv:0709.3900

Date: Tue, 25 Sep 2007 09:17:56 GMT (485kb)

Title: Nonlinear tunneling in two-dimensional lattices

Authors: V.A. Brazhnyi, V.V. Konotop, V. Kuzmiak, and V.S. Shchesnovich

Categories: cond-mat.other

Journal-ref: Phys. Rev. A 76, 023608 (2007)

\\

We present thorough analysis of the nonlinear tunneling of Bose-Einstein

condensates in static and accelerating two-dimensional lattices within the

framework of the mean-field approximation. We deal with nonseparable lattices

considering different initial atomic distributions in the highly symmetric

states. For analytical description of the condensate before instabilities are

developed, we derive several few-mode models, analyzing both essentially

nonlinear and quasi-linear regimes of tunneling. By direct numerical

simulations, we show that two-mode models provide accurate description of the

tunneling when either initially two states are populated or tunneling occurs

between two stable states. Otherwise a two-mode model may give only useful

qualitative hints for understanding tunneling but does not reproduce many

features of the phenomenon. This reflects crucial role of the instabilities

developed due to two-body interactions resulting in non-negligible population

of the higher bands. This effect becomes even more pronounced in the case of

accelerating lattices. In the latter case we show that the direction of the

acceleration is a relevant physical parameter which affects the tunneling by

changing the atomic rates at different symmetric states and by changing the

numbers of bands involved in the atomic transfer.

\\ ( http://arxiv.org/abs/0709.3900 , 485kb)

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arXiv:0709.4050

Date: Wed, 26 Sep 2007 04:26:57 GMT (358kb)

Title: Extended Gutzwiller Approximation for Inhomogenous System

Authors: Wing-Ho Ko, Cody P. Nave, Patrick A. Lee

Categories: cond-mat.str-el

Comments: 12 pages, 1 table, 6 figures

\\

The generalization of the Gutzwiller approximation to inhomogeneous systems

is considered, with extra spin-and-site-dependent fugacity factors included. It

is found that the inclusion of fugacity factors reconciles the seemingly

contradictory choices of Gutzwiller factors used in the literature. Moreover,

from the derivation of the Gutzwiller factors, it is shown that the Gutzwiller

approximation breaks the rotational symmetry of the trial wavefunctions, and

that different components of the spin-spin interaction need to be renormalized

differently under the approximation. Various schemes to restore the rotational

symmetry are discussed and are compared with results from variational

Monte-Carlo calculations for the two-dimensional square-lattice

antiferromagnet. Results along different paths within the full parameter space,

which corresponds to different choices of fugacity factors in the literature,

are also compared.

\\ ( http://arxiv.org/abs/0709.4050 , 358kb)

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arXiv:0709.4022 (*cross-listing*)

Date: Tue, 25 Sep 2007 19:55:07 GMT (17kb)

Title: The Lieb-Liniger Model as a Limit of Dilute Bosons in Three Dimensions

Authors: Robert Seiringer, Jun Yin

Categories: math-ph cond-mat.stat-mech math.MP

Comments: LaTeX2e, 19 pages

\\

We show that the Lieb-Liniger model for one-dimensional bosons with repulsive

$\delta$-function interaction can be rigorously derived via a scaling limit

from a dilute three-dimensional Bose gas with arbitrary repulsive interaction

potential of finite scattering length. For this purpose, we prove bounds on

both the eigenvalues and corresponding eigenfunctions of three-dimensional

bosons in strongly elongated traps and relate them to the corresponding

quantities in the Lieb-Liniger model. In particular, if both the scattering

length $a$ and the radius $r$ of the cylindrical trap go to zero, the

Lieb-Liniger model with coupling constant $g \sim a/r^2$ is derived. Our bounds

are uniform in $g$ in the whole parameter range $0\leq g\leq \infty$, and apply

to the Hamiltonian for three-dimensional bosons in a spectral window of size

$\sim r^{-2}$ above the ground state energy.

\\ ( http://arxiv.org/abs/0709.4022 , 17kb)

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arXiv:0709.4109

Date: Wed, 26 Sep 2007 15:20:43 GMT (41kb)

Title: Enhanced Deflection of Light Ray by Atomic Ensemble on Coherent

Population Oscillation

Authors: Jing Lu, Lan Zhou, Le-Man Kuang, C. P. Sun

Categories: quant-ph

Comments: 7pages, 2 figures

\\

In recent experiments[e.g., Nature Physics \textbf{2}, 332 (2006)], the

enhancing light deflection in an atomic ensemble due to inhomogeneous fields is

shown by the electromagnetically induced transparency (EIT) based mechanism. In

this paper, we explore an different mechanism for the similar phenomenon of the

enhanced light deflection. This mechanism is based on the coherent population

oscillation, which results in the hole burning of the dispersion windows. The

medium causing the deflection of probe light is an ensemble of two level atoms

manipulated by a strong controlled field on the two photon resonances. In the

large detuning condition, the response of the medium to the pump field and

signal field is obtained with steady state approximation. And it is found that

after the probe field traveling across the medium, the signal ray bends due to

the spatial-dependent profile of the control beam.

\\ ( http://arxiv.org/abs/0709.4109 , 41kb)

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arXiv:0709.4151

Date: Wed, 26 Sep 2007 13:52:30 GMT (25kb)

Title: Universal description of the rotational-vibrational spectrum of three

particles with zero-range interactions

Authors: O. I. Kartavtsev and A. V. Malykh

Categories: physics.atom-ph

\\

A comprehensive universal description of the rotational-vibrational spectrum

for two identical particles of mass $m$ and the third particle of the mass

$m_1$ in the zero-range limit of the interaction between different particles is

given for arbitrary values of the mass ratio $m/m_1$ and the total angular

momentum $L$. If the two-body scattering length is positive, a number of

vibrational states is finite for $L_c(m/m_1) \le L \le L_b(m/m_1)$, zero for

$L>L_b(m/m_1)$, and infinite for $L<L_c(m/m_1)$. If the two-body scattering

length is negative, a number of states is either zero for $L \ge L_c(m/m_1)$ or

infinite for $L<L_c(m/m_1)$. For a finite number of vibrational states, all the

binding energies are described by the universal function $\epsilon_{LN}(m/m_1)

= {\cal E}(\xi, \eta)$, where $\xi=\displaystyle\frac{N-1/2}{\sqrt{L(L + 1)}}$,

$\eta=\displaystyle\sqrt{\frac{m}{m_1 L (L + 1)}}$,and $N$ is the vibrational

quantum number. This scaling dependence is in agreement with the numerical

calculations for $L > 2$ and only slightly deviates from those for $L = 1, 2$.

The universal description implies that the critical values $L_c(m/m_1)$ and

$L_b(m/m_1)$ increase as $0.401 \sqrt{m/m_1}$ and $0.563 \sqrt{m/m_1}$,

respectively, while a number of vibrational states for $L \ge L_c(m/m_1)$ is

within the range $N \le N_{max} \approx 1.1 \sqrt{L(L+1)}+1/2$.

\\ ( http://arxiv.org/abs/0709.4151 , 25kb)

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arXiv:0709.4024

Date: Tue, 25 Sep 2007 20:00:08 GMT (7kb)

Title: Shut up and calculate

Authors: Max Tegmark (MIT)

Categories: physics.pop-ph hep-th

Comments: This is the "director's cut" version of the September 15 2007 New

Scientist cover story. For references, see the "full strength" version at

arXiv:0704.0646

\\

I advocate an extreme "shut-up-and-calculate" approach to physics, where our

external physical reality is assumed to be purely mathematical. This brief

essay motivates this "it's all just equations" assumption and discusses its

implications.

\\ ( http://arxiv.org/abs/0709.4024 , 7kb)

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arXiv:0709.4335

Date: Thu, 27 Sep 2007 09:15:13 GMT (33kb)

Title: Localization of an impurity particle on a boson Mott insulator

background

Authors: Sevilay Sevincli, R. O. Umucalilar, M. O. Oktel

Categories: cond-mat.other

Comments: 11 pages, 9 figures

\\

We investigate the behavior of a single particle hopping on a three

dimensional cubic optical lattice in the presence of a Mott insulator of bosons

in the same lattice. We calculate the critical interaction strength between the

impurity and background bosons, beyond which there is bound state (polaron)

formation. We give exact results in the limit of a perfect Mott insulator,

where polaron formation is equivalent to impurity localization. We calculate

the effects of lattice anisotropy, higher impurity bands, and fluctuations of

the Mott insulator on the localization threshold. We argue that our results can

be checked experimentally by RF spectroscopy of impurity particles.

\\ ( http://arxiv.org/abs/0709.4335 , 33kb)

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arXiv:0709.4357

Date: Thu, 27 Sep 2007 11:00:03 GMT (368kb)

Title: Collective excitations of BEC under anharmonic trap position jittering

Authors: F. Kh. Abdullaev, R. M. Galimzyanov and Kh. N. Ismatullaev

Categories: cond-mat.other

Comments: This paper contains a manuscript - SolAnJPB.tex and figures (fig1 -

fig1a.eps and fig1b.eps, fig2 - fig2.eps, fig3 - fig3a.eps and fig3b.eps,

fig4 - fig4a.eps and fig4b.eps). The manuscript has been prepared using

LATEX2e with the iopart class and the figures in encapsulated PostScript

\\

Collective excitations of a Bose-Einstein condensate under periodic

oscillations of a quadratic plus quartic trap position has been studied. A

coupled set of variational equations is derived for the width and the

condensate wave function center. Analytical expressions for the growth of

oscillation amplitudes in the resonance case are derived. It is shown that

jittering of an anharmonic trap position can cause double resonance of the BEC

width and the center of mass oscillation in the wide range of the BEC

parameters values. The predictions of variational approach are confirmed by

full numerical simulations of the 1D GP equation.

\\ ( http://arxiv.org/abs/0709.4357 , 368kb)

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arXiv:0709.4424

Date: Thu, 27 Sep 2007 15:28:37 GMT (66kb)

Title: Fermi-Fermi Mixtures in the Strong Attraction Limit

Authors: M. Iskin and C. A. R. Sa de Melo

Categories: cond-mat.supr-con cond-mat.other

Comments: 12 Pages, 6 Figures and 1 Table

\\

The phase diagrams of low density Fermi-Fermi mixtures with equal or unequal

masses and equal or unequal populations are described at zero and finite

temperatures in the strong attraction limit. In this limit, the Fermi-Fermi

mixture can be described by a weakly interacting Bose-Fermi mixture, where the

bosons correspond to Feshbach molecules and the fermions correspond to excess

atoms. First, we discuss the three and four fermion scattering processes, and

use the exact boson-fermion and boson-boson scattering lengths to generate the

phase diagrams in terms of the underlying fermion-fermion scattering length. In

three dimensions, in addition to the normal and uniform superfluid phases, we

find two stable non-uniform states corresponding to (1) phase separation

between pure unpaired (excess) and pure paired fermions (molecular bosons); and

(2) phase separation between pure excess fermions and a mixture of excess

fermions and molecular bosons. Lastly, we also discuss the effects of the

trapping potential in the density profiles of condensed and non-condensed

molecular bosons, and excess fermions at zero and finite temperatures, and

discuss possible implications of our findings to experiments involving mixtures

of ultracold fermions.

\\ ( http://arxiv.org/abs/0709.4424 , 66kb)

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arXiv:0709.4436

Date: Thu, 27 Sep 2007 15:58:36 GMT (135kb)

Title: The Amplitude Mode in the Quantum Phase Model

Authors: S.D. Huber, B. Theiler, E. Altman, and G. Blatter

Categories: cond-mat.other

Comments: 4 pages, 3 figures

\\

We derive the collective low energy excitations of the quantum phase model of

interacting lattice bosons within the superfluid state using a dynamical

variational approach. We recover the well known sound (or Goldstone) mode and

derive a gapped (Higgs type) mode that was overlooked in previous studies of

the quantum phase model. This mode is relevant to ultracold atoms in a strong

optical lattice potential. We predict the signature of the gapped mode in

lattice modulation experiments and show how it evolves with increasing

interaction strength.

\\ ( http://arxiv.org/abs/0709.4436 , 135kb)

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arXiv:0709.4260

Date: Wed, 26 Sep 2007 20:41:40 GMT (138kb)

Title: Geometric resonance cooling of polarizable particles in an optical

waveguide

Authors: G. Szirmai, P. Domokos

Categories: quant-ph

Comments: 4 pages

\\

In the radiation field of an optical waveguide, the Rayleigh scattering of

photons is shown to result in a strongly velocity-dependent force on atoms. The

pump field, which is injected in the fundamental branch of the waveguide, is

favorably scattered by a moving atom into one of the transversely excited

branches of propagating modes. All fields involved are far detuned from any

resonances of the atom. For a simple polarizable particle, a linear friction

force coefficient comparable to that of cavity cooling can be achieved.

\\ ( http://arxiv.org/abs/0709.4260 , 138kb)

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arXiv:0709.4268

Date: Thu, 27 Sep 2007 00:00:35 GMT (53kb)

Title: Coherence lifetimes of excitations in an atomic condensate due to the

thin spectrum

Authors: T. Birol, T. Dereli, \"O. E. M\"ustecapl{\i}o\u{g}lu, L. You

Categories: quant-ph

\\

We study the quantum coherence properties of a finite sized atomic condensate

using a toy-model and the thin spectrum model formalism. The decoherence time

for a condensate in the ground state, nominally taken as a variational symmetry

breaking state, is investigated for both zero and finite temperatures. We also

consider the lifetimes for Bogoliubov quasi-particle excitations, and contrast

them to the observability window determined by the ground state coherence time.

The lifetimes are shown to exhibit a general characteristic dependence on the

temperature, determined by the thin spectrum accompanying the spontaneous

symmetry breaking ground state.

\\ ( http://arxiv.org/abs/0709.4268 , 53kb)

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arXiv:0709.4320

Date: Thu, 27 Sep 2007 06:53:20 GMT (248kb)

Title: Experimental observation of the Anderson transition with atomic matter

waves

Authors: Julien Chab\'e (PhLAM, CERLA), Gabriel Lemari\'e (LKB - Jussieu),

Beno\^it Gr\'emaud (LKB - Jussieu), Dominique Delande (LKB - Jussieu), Pascal

Szriftgiser (PhLAM, CERLA), Jean Claude Garreau (PhLAM, CERLA)

Categories: quant-ph

Comments: 16 pages, 4 color figures, word 2003 document

Proxy: ccsd hal-00175097

\\

Phase transitions are major phenomena in physics. Of particular interest in

modern physics is the metal-insulator Anderson transition in disordered

systems, ultimately due to the interplay between quantum interference and

disorder. We present the first experimental observation of the Anderson

transition using atomic matter waves. The metal-insulator transition plays a

central role in the study of quantum disordered systems, and has been extended

from its original solid-state scope to many different fields, including

dynamical systems, electromagnetic radiation, acoustics, biology and even

cosmology. Many studies have also pointed out strong analogies between cold

atoms trapped in optical lattices and condensed matter. Using an atom-optics

system formally equivalent to the 3D Anderson model we unambiguously

demonstrate the Anderson transition. Sensitive measurements of the atomic

dynamics and the use of finite-size scaling techniques make it possible to

extract both the critical disorder strength and the critical exponent of the

transition. In doing so, we make use of the physical concepts underlying phase

transition phenomena: universality classes (i.e., the insensitivity of the

critical phenomena to the microscopic properties of the system) and

renormalization (which describes the scaling laws in the vicinity of the

transition).

\\ ( http://arxiv.org/abs/0709.4320 , 248kb)

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\\

arXiv:0709.4349

Date: Thu, 27 Sep 2007 10:08:29 GMT (13kb)

Title: Bose-Einstein condensate in a harmonic trap with an eccentric dimple

potential

Authors: Haydar Uncu, Devrim Tarhan, Ersan Demiralp, Ozgur E. Mustecaplioglu

Categories: quant-ph

Comments: 12 pages, 5 figures, International Laser Physics Workshop. to be

appear in Laser Physics

\\

We investigate Bose-Einstein condensation of noninteracting gases in a

harmonic trap with an off-center dimple potential. We specifically consider the

case of a tight and deep dimple potential which is modelled by a point

interaction. This point interaction is represented by a Dirac delta function.

The atomic density, chemical potential, critical temperature and condensate

fraction, the role of the relative depth and the position of the dimple

potential are analyzed by performing numerical calculations.

\\ ( http://arxiv.org/abs/0709.4349 , 13kb)

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The replacements:

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\\

arXiv:0707.1205

replaced with revised version Fri, 21 Sep 2007 18:32:56 GMT (389kb)

Title: Non-Equilibrium Dynamics and Superfluid Ring Excitations in Binary

Bose-Einstein Condensates

Authors: K. M. Mertes, J. Merrill, R. Carretero-Gonzalez, D. J. Frantzeskakis,

P. G. Kevrekidis, and D. S. Hall

Categories: cond-mat.other

Comments: 4 pages, 3 figures (low res.), to appear in PRL

\\ ( http://arxiv.org/abs/0707.1205 , 389kb)

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\\

arXiv:cond-mat/0702555

replaced with revised version Sat, 22 Sep 2007 21:36:20 GMT (36kb)

Title: Bold Diagrammatic Monte Carlo: When Sign Problem is Welcome

Authors: Nikolay Prokof'ev and Boris Svistunov

Categories: cond-mat.stat-mech cond-mat.str-el

Comments: 4 pages, 2 figures, revtex4

\\ ( http://arxiv.org/abs/cond-mat/0702555 , 36kb)

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\\

arXiv:0705.4352

replaced with revised version Mon, 24 Sep 2007 11:41:06 GMT (277kb)

Title: Signal of Bose condensation in an optical lattice at finite temperature

Authors: W. Yi, G.-D. Lin, and L.-M. Duan

Categories: cond-mat.other

Comments: 4 pages, 2 figures, replaced with the published version

Journal-ref: Phys. Rev. A 76, 031602(R) (2007)

DOI: 10.1103/PhysRevA.76.031602

\\ ( http://arxiv.org/abs/0705.4352 , 277kb)

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\\

arXiv:0707.4259

replaced with revised version Mon, 24 Sep 2007 18:04:29 GMT (23kb)

Title: Fermi-Polaron: Diagrammatic Monte Carlo for Divergent Sign-Alternating

Series

Authors: Nikolay Prokof'ev and Boris Svistunov

Categories: cond-mat.stat-mech

Comments: 4 pages, 7 figures

\\ ( http://arxiv.org/abs/0707.4259 , 23kb)

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\\

arXiv:0709.2425

replaced with revised version Sat, 22 Sep 2007 12:16:31 GMT (28kb)

Title: Detection of acceleration radiation in a Bose-Einstein condensate

Authors: A. Retzker, J. I. Cirac, M. B. Plenio, B. Reznik

Categories: quant-ph

Comments: 5 pages, 3 figures

\\ ( http://arxiv.org/abs/0709.2425 , 28kb)

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\\

arXiv:cond-mat/0701484

replaced with revised version Wed, 26 Sep 2007 11:58:21 GMT (57kb)

Title: Finite temperature phase diagram of a polarized Fermi gas in an optical

lattice

Authors: T.K. Koponen, T. Paananen, J.-P. Martikainen, and P. Torma

Categories: cond-mat.supr-con cond-mat.other

Comments: Journal version

Journal-ref: Phys. Rev. Lett. 99, 120403 (2007)

\\ ( http://arxiv.org/abs/cond-mat/0701484 , 57kb)

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\\

arXiv:0705.1502

replaced with revised version Wed, 26 Sep 2007 19:06:09 GMT (34kb)

Title: Three fermions in a box at the unitary limit: universality in a lattice

model

Authors: Ludovic Pricoupenko (LPTMC), Yvan Castin (LKB - Lhomond)

Categories: cond-mat.other

Comments: 6 pages

Proxy: ccsd hal-00145589

\\ ( http://arxiv.org/abs/0705.1502 , 34kb)

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\\

arXiv:0706.4123

replaced with revised version Wed, 26 Sep 2007 13:39:20 GMT (808kb)

Title: Level crossing in the three-body problem for strongly interacting

fermions in a harmonic trap

Authors: J. P. Kestner, L.-M. Duan

Categories: cond-mat.other

Comments: 5 pages, 6 figures, typos corrected, references added

Journal-ref: Phys. Rev. A 76, 033611 (2007)

DOI: 10.1103/PhysRevA.76.033611

\\ ( http://arxiv.org/abs/0706.4123 , 808kb)

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\\

arXiv:0709.1444

replaced with revised version Wed, 26 Sep 2007 07:56:42 GMT (64kb)

Title: Fermi-Bose transformation for the time-dependent Lieb-Liniger gas

Authors: H. Buljan, R. Pezer, T. Gasenzer

Categories: cond-mat.other

Comments: 4+ pages, 1 figure; added references

\\ ( http://arxiv.org/abs/0709.1444 , 64kb)

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\\

arXiv:quant-ph/0702067

replaced with revised version Wed, 26 Sep 2007 11:06:23 GMT (92kb,D)

Title: Spatial Entanglement From Off-Diagonal Long Range Order in a BEC

Authors: Libby Heaney, Janet Anders, Dagomir Kaszlikowski, Vlatko Vedral

Categories: quant-ph

Comments: 7 pages, 3 figures. Extended from 4 to 7 pages. More detailed

derivations of key formula. Extended introduction and background. Results

remain unchanged

\\ ( http://arxiv.org/abs/quant-ph/0702067 , 92kb)

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\\

arXiv:0705.1324

replaced with revised version Thu, 27 Sep 2007 17:39:25 GMT (340kb)

Title: Bright-Dark Soliton Complexes in Spinor Bose-Einstein Condensates

Authors: H.E. Nistazakis, D.J. Frantzeskakis, P.G. Kevrekidis, B.A. Malomed, R.

Carretero-Gonzalez

Categories: cond-mat.other

Comments: 10 pages, 4 figures. Submitted to PRA, May 2007

\\ ( http://arxiv.org/abs/0705.1324 , 340kb)

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Till next time,

Matt.

-- ========================================================================= Dr M. J. Davis, Senior Lecturer in Physics School of Physical Sciences, email: mdavis_at_physics.uq.edu.au University of Queensland, ph : +61 7 334 69824 Brisbane, QLD 4072, fax : +61 7 336 51242 Australia. http://www.physics.uq.edu.au/people/mdavis/ ========================================================================= 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 Sun Oct 14 2007 - 13:06:52 EST

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