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

Date: Fri, 10 Jul 2009 14:37:39 +1000

Date: Fri, 10 Jul 2009 14:37:39 +1000

Dear subscribers,

This week Simon Haine compiled the list of abstracts. There are 14 new

preprints and 10 replacements:

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arXiv:0905.4750

Date: Thu, 28 May 2009 21:09:05 GMT (301kb)

Title: Transport of ultracold Bose gases beyond the Gross-Pitaevskii

description

Authors: Thomas Ernst, Tobias Paul, and Peter Schlagheck

Categories: cond-mat.quant-gas

Comments: 12 pages, 7 figures

\\

We explore atom-laser-like transport processes of ultracold Bose-condensed

atomic vapors in mesoscopic waveguide structures beyond the Gross-Pitaevskii

mean-field theory. Based on a microscopic description of the transport process

in the presence of a coherent source which models the outcoupling from a

reservoir of perfectly Bose-Einstein condensed atoms, we derive a system of

coupled quantum evolution equations that describe the dynamics of a dilute

condensed Bose gas in the framework of the Hartree-Fock-Bogoliubov

approximation. We apply this method to study the transport of dilute Bose gases

through an atomic quantum dot and through waveguides with disorder. Our

numerical simulations reveal that the onset of an explictly time-dependent flow

corresponds to the appearance of strong depletion of the condensate on the

microscopic level and leads to a loss of global phase coherence.

\\ ( http://arxiv.org/abs/0905.4750 , 301kb)

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arXiv:0905.4783

Date: Fri, 29 May 2009 04:21:41 GMT (107kb)

Title: Critical temperature of a Bose gas in an optical lattice

Authors: D. Baillie and P. B. Blakie

Categories: cond-mat.quant-gas

Comments: 4 pages, 4 figures

\\

We present a theory for the critical temperature of a Bose gas in a combined

harmonic lattice potential based on a mean-field description of the system. We

develop practical expressions for the ideal-gas critical temperature, and

corrections due to interactions, the finite-size effect, and the occupation of

excited bands. We compare our expressions to numerical calculations and find

excellent agreement over a wide parameter regime.

\\ ( http://arxiv.org/abs/0905.4783 , 107kb)

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arXiv:0905.4817

Date: Fri, 29 May 2009 10:04:24 GMT (24kb)

Title: High-field instability of low-temperature magnon Bose-Einstein

condensate

Authors: Abdulla Rakhimov, E. Ya. Sherman and Chul Koo Kim

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

Comments: 13 pages, 4 figures, Revtex

\\

We study the instability of the low-temperature Bose-Einstein condensation

(BEC) of magnons in magnetic dielectrics as a function of the temperature and

external magnetic field within the Hartree-Fock-Bogoliubov approach including

the anomalous density. We show that magnetization is continuous across the

transition, in agreement with the experiment. In sufficiently high fields the

condensate becomes unstable due to the magnon-magnon repulsion. As a result,

the system is characterized by two critical magnetic fields: one producing the

condensate and the other destroying it. We show that nonparabolic magnon

dispersion arising due to the gapped bare spectrum and the crystal structure

has the crucial influence on the magnon BEC phase diagram, making the stability

region smaller than it would be expected for the parabolic dispersion.

\\ ( http://arxiv.org/abs/0905.4817 , 24kb)

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arXiv:0905.4833

Date: Fri, 29 May 2009 11:29:35 GMT (52kb)

Title: Quantum quenches in the Dicke model: statistics of the work done and of

other observables

Authors: Francis N.C. Paraan, Alessandro Silva

Categories: cond-mat.stat-mech

Comments: 8 pages, 2 figures

\\

We study the statistics of the work done in a zero temperature quench of the

coupling constant in the Dicke model describing the interaction between a gas

of two level atoms and a single electromagnetic cavity mode. When either the

final or the initial coupling constants approach the critical coupling

$\lambda_c$ that separates the normal and superradiant phases of the system,

the probability distribution of the work done displays singular behavior. The

average work tends to diverge as the initial coupling parameter is brought

closer to the critical value $\lambda_c$. In contrast, for quenches ending

close to criticality, the distribution of work has finite moments but displays

a sequence of edge singularities. This contrasting behavior is related to the

difference between the processes of compression and expansion of a particle

subject to a sudden change of its confining potential. We confirm this by

studying in detail the time dependent statistics of other observables, such as

the quadratures of the photons and the total occupation of the bosonic modes.

\\ ( http://arxiv.org/abs/0905.4833 , 52kb)

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arXiv:0905.4880

Date: Fri, 29 May 2009 14:43:35 GMT (318kb,D)

Title: Assessing the accuracy of projected entangled-pair states on infinite

lattices

Authors: Bela Bauer and Guifre Vidal and Matthias Troyer

Categories: cond-mat.str-el

Comments: 9 pages, 12 figures

\\

Generalizations of the density-matrix renormalization group method have long

been sought after. In this paper, we assess the accuracy of tensor-product

states/projected entangled-pair states on infinite lattices by comparing with

Quantum Monte Carlo results for several non-frustrated spin-1/2 systems.

Furthermore, we apply the method to a frustrated quantum system.

\\ ( http://arxiv.org/abs/0905.4880 , 318kb)

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arXiv:0905.4882

Date: Fri, 29 May 2009 14:44:19 GMT (1316kb)

Title: Suppression of the critical temperature for superfluidity near the Mott

transition: validating a quantum simulator

Authors: S. Trotzky, L. Pollet, F. Gerbier, U. Schnorrberger, I. Bloch, N.V.

Prokof'ev, B. Svistunov, M. Troyer

Categories: cond-mat.quant-gas

\\

Ultracold atomic gases in optical lattices have proven to be a controllable,

tunable and clean implementation of strongly interacting quantum many-body

systems. An essential prospect for such quantum simulators is their ability to

map out the phase diagram of fundamental many-body model Hamiltonians. However,

the results need to be validated first for representative benchmark problems

via state-of-the-art numerical methods of quantum many-body theory. Here we

present the first ab-initio comparison between experiments and quantum Monte

Carlo simulations for strongly interacting Bose gases on a lattice for large

systems (up to N = 3e5 particles). The comparison has enabled us to perform

thermometry for the interacting quantum gas and to experimentally determine the

finite temperature phase diagram for bosonic superfluids in an optical lattice.

Our results reveal a downshift of the critical temperature as the transition to

the Mott insulator is approached.

\\ ( http://arxiv.org/abs/0905.4882 , 1316kb)

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arXiv:0905.4780

Date: ?

Title: Mapping out atom-wall interaction with atomic clocks

Authors: A. Derevianko, B. Obreshkov, V. A. Dzuba

Categories: physics.atom-ph

Comments: 4 pages, 4 figures

\\

We explore a feasibility of measuring atom-wall interaction using atomic

clocks based on atoms trapped in engineered optical lattices. Optical lattice

is normal to the wall.

By monitoring the wall-induced clock shift at individual wells of the

lattice, one would measure a dependence of the atom-wall interaction on the

atom-wall separation. We rigorously evaluate the relevant clock shifts and show

that the proposed scheme may uniquely probe the long-range atom-wall

interaction in all three qualitatively-distinct regimes of the interaction: van

der Waals (image-charge interaction), Casimir-Polder (QED vacuum fluctuations)

and Lifshitz (thermal bath fluctuations). The analysis is carried out for atoms

Mg, Ca, Sr, Cd, Zn, and Hg, with a particular emphasis on Sr clock.

\\ ( http://arxiv.org/abs/0905.4780 , 1213kb)

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arXiv:0906.0016

Date: ?

Title: Entanglement Entropy and Mutual Information in Bose-Einstein Condensates

Authors: Wenxin Ding, Kun Yang

Categories: quant-ph

Comments: 13 pages, 6 figures

\\

In this paper we study the entanglement properties of free {\em

non-relativistic} Bose gases. At zero temperature, we calculate the bipartite

block entanglement entropy of the system, and find it diverges logarithmically

with the particle number in the subsystem. For finite temperatures, we study

the mutual information between the two blocks. We first analytically study an

infinite-range hopping model, then numerically study a set of long-range

hopping models in one-deimension that exhibit Bose-Einstein condensation. In

both cases we find that a Bose-Einstein condensate, if present, makes a

divergent contribution to the mutual information which is proportional to the

logarithm of the number of particles in the condensate in the subsystem. The

prefactor of the logarithmic divergent term is model dependent.

\\ ( http://arxiv.org/abs/0906.0016 , 125kb)

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arXiv:0906.0484

Date: Tue, 2 Jun 2009 13:54:35 GMT (71kb)

Title: Had the planet mars not existed: Kepler's equant model and its physical

consequences

Authors: Christian Bracco, Jean-Pierre Provost

Categories: physics.hist-ph physics.gen-ph

\\

We examine the equant model for the motion of planets, which has been the

starting point of Kepler's investigations before he modified it because of Mars

observations. We show that, up to first order in eccentricity, this model

implies for each orbit a velocity which satisfies Kepler's second law and

Hamilton's hodograph, and a centripetal acceleration with an inverse square

dependence on the distance to the sun. If this dependence is assumed to be

universal, Kepler's third law follows immediately. This elementary execice in

kinematics for undergraduates emphasizes the proximity of the equant model

coming from Ancient Greece with our present knowledge. It adds to its

historical interest a didactical relevance concerning, in particular, the

discussion of the Aristotelian or Newtonian conception of motion.

\\ ( http://arxiv.org/abs/0906.0484 , 71kb)

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arXiv:0906.0868

Date: Thu, 4 Jun 2009 09:57:44 GMT (969kb)

Title: Condensate density of interacting bosons: a functional renormalization

group approach

Authors: Christopher Eichler, Nils Hasselmann, and Peter Kopietz

Categories: cond-mat.quant-gas

Comments: 9 pages, 6 figures

\\

We calculate the temperature dependent condensate density $\rho^0 (T)$ of

interacting bosons in three dimensions using the functional renormalization

group (FRG). From the numerical solution of suitably truncated FRG flow

equations for the irreducible vertices we obtain $\rho^0 (T)$ for arbitrary

temperatures. We carefully extrapolate our numerical results to the critical

point and determine the order parameter exponent $\beta \approx 0.32$, in

reasonable agreement with the expected value $ 0.345$ associated with the

XY-universality class. We also calculate the condensate density in two

dimensions at zero temperature using a truncation of the FRG flow equations

based on the derivative expansion including cubic and quartic terms in the

expansion of the effective potential in powers of the density. As compared with

the widely used quadratic approximation for the effective potential, the

coupling constants associated with the cubic and quartic terms increase the

result for the condensate density by a few percent. However, the cubic and

quartic coupling constants flow to rather large values, which sheds some doubt

on FRG calculations based on a low order polynomial approximation for the

effective potential.

\\ ( http://arxiv.org/abs/0906.0868 , 969kb)

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arXiv:0906.0952

Date: Thu, 4 Jun 2009 18:35:43 GMT (13kb)

Title: The explicit expression of the fugacity for hard-sphere Bose and Fermi

gases

Authors: Wu-Sheng Dai, Mi Xie

Categories: cond-mat.stat-mech

Comments: 15 pages, no figure

\\

In this paper, we calculate the explicit expression for the fugacity for

three-dimensional hard-sphere Bose and Fermi gases from their equations of

state in isochoric and isobaric processes, respectively, based on the

mathematical result of the boundary problem of an analytic function -- the

homogeneous Riemann-Hilbert problem.

\\ ( http://arxiv.org/abs/0906.0952 , 13kb)

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arXiv:0906.0955

Date: Thu, 4 Jun 2009 18:21:50 GMT (40kb,D)

Title: Polarization Suppression and Nonmonotonic Local Two-Body Correlations in

the Two-Component Bose Gas in One Dimension

Authors: J.-S. Caux, A. Klauser and J. van den Brink

Categories: cond-mat.quant-gas

Comments: 4 pages, 6 figures

\\

We study the interplay of quantum statistics, strong interactions and finite

temperatures in the two-component (spinor) Bose gas with repulsive

delta-function interactions in one dimension. Using the Thermodynamic Bethe

Ansatz, we obtain the equation of state, population densities and local density

correlation numerically as a function of all physical parameters (interaction,

temperature and chemical potentials), quantifying the full crossover between

low-temperature ferromagnetic and high-temperature unpolarized regimes. In

contrast to the single-component, Lieb-Liniger gas, nonmonotonic behaviour of

the local density correlation as a function of temperature is observed.

\\ ( http://arxiv.org/abs/0906.0955 , 40kb)

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arXiv:0906.0962

Date: Thu, 4 Jun 2009 19:00:47 GMT (114kb)

Title: Quantum-limited metrology and Bose-Einstein condensates

Authors: Sergio Boixo, Animesh Datta, Matthew J. Davis, Anil Shaji, Alexandre

B. Tacla and Carlton M. Caves

Categories: quant-ph

Comments: 32 pages, 1 figure

\\

We discuss a quantum-metrology protocol designed to estimate a physical

parameter in a Bose-Einstein condensate of N atoms, and we show that the

measurement uncertainty can decrease faster than 1/N. The 1/N scaling is

usually thought to be the best possible in any measurement scheme. From the

perspective of quantum information theory, we outline the main idea that leads

to a measurement uncertainty that scales better than 1/N. We examine in detail

some potential problems and challenges that arise in implementing such a

measurement protocol using a Bose-Einstein condensate. We discuss how some of

these issues can be dealt with by using lower-dimensional condensates trapped

in nonharmonic potentials.

\\ ( http://arxiv.org/abs/0906.0962 , 114kb)

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arXiv:0906.0946

Date: Thu, 4 Jun 2009 17:13:04 GMT (1114kb,D)

Title: Magnetic trapping of ultracold Rydberg atoms in low angular momentum

states

Authors: Michael Mayle, Igor Lesanovsky, and Peter Schmelcher

Categories: physics.atom-ph

Comments: 12 pages, 7 figures

\\

We theoretically investigate the quantum properties of nS, nP, and nD Rydberg

atoms in a magnetic Ioffe-Pritchard trap. In particular, it is demonstrated

that the two-body character of Rydberg atoms significantly alters the trapping

properties opposed to point-like particles with identical magnetic moment.

Approximate analytical expressions describing the resulting Rydberg trapping

potentials are derived and their validity is confirmed for experimentally

relevant field strengths by comparisons to numerical solutions of the

underlying Schroedinger equation. In addition to the electronic properties, the

center of mass dynamics of trapped Rydberg atoms are studied. In particular, we

analyze the influence of a short-time Rydberg excitation, as required by

certain quantum-information protocols, on the center of mass dynamics of

trapped ground state atoms. A corresponding heating rate is derived and the

implications for the purity of the density matrix of an encoded qubit are

investigated.

\\ ( http://arxiv.org/abs/0906.0946 , 1114kb)

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The replacements:

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arXiv:0805.3693

replaced with revised version Fri, 29 May 2009 10:59:56 GMT (355kb)

Title: Itinerant Ferromagnetism in an Atom Trap

Authors: Ilya Berdnikov, P. Coleman, Steven H. Simon

Categories: cond-mat.str-el

Comments: Final Published version. References added

\\ ( http://arxiv.org/abs/0805.3693 , 355kb)

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arXiv:0905.1708

replaced with revised version Fri, 29 May 2009 01:40:17 GMT (108kb)

Title: Mesoscopic quantum switching of a Bose-Einstein condensate in an optical

lattice governed by the parity of the number of atoms

Authors: V. S. Shchesnovich

Categories: cond-mat.quant-gas

Comments: 4 pages, 3 figures in color

\\ ( http://arxiv.org/abs/0905.1708 , 108kb)

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arXiv:0905.4652

replaced with revised version Fri, 29 May 2009 17:20:08 GMT (86kb)

Title: Sudden Death and Birth of Entanglement Effects for Kerr-Nonlinear

Coupler

Authors: A. Kowalewska-Kud{\l}aszyk and W. Leo\'nski

Categories: quant-ph

Comments: 18 pages including 7 figures. Journal of the Optical Society of

America B - in press

\\ ( http://arxiv.org/abs/0905.4652 , 86kb)

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arXiv:0808.0479

replaced with revised version Fri, 29 May 2009 20:51:19 GMT (9kb)

Title: Dynamics of a one-dimensional spinor Bose liquid: a phenomenological

approach

Authors: A. Kamenev and L.I. Glazman

Categories: cond-mat.mes-hall cond-mat.other

Comments: 4 pages,

\\ ( http://arxiv.org/abs/0808.0479 , 9kb)

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arXiv:0712.3466

replaced with revised version Sat, 30 May 2009 13:42:12 GMT (160kb)

Title: Interpretation of quantum theory - An overview

Authors: Dimitris Lazarou

Categories: quant-ph

Comments: 11 pages; added mathematical formalism, updated references

\\ ( http://arxiv.org/abs/0712.3466 , 160kb)

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arXiv:0903.3194

replaced with revised version Tue, 2 Jun 2009 08:58:16 GMT (97kb)

Title: 60 years of Broken Symmetries in Quantum Physics (From the Bogoliubov

Theory of Superfluidity to the Standard Model)

Authors: D. V. Shirkov

Categories: physics.hist-ph cond-mat.supr-con hep-ph hep-th

Comments: 18 pages, 4 figures, to appear in Physics -- Uspekhi, June 2009. Two

figures are upgraded and small text modifications with few new references are

made

\\ ( http://arxiv.org/abs/0903.3194 , 97kb)

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arXiv:0902.0934

replaced with revised version Wed, 3 Jun 2009 05:25:04 GMT (2121kb)

Title: Interaction of dark-bright solitons in two-component Bose-Einstein

condensates

Authors: S. Rajendran, P. Muruganandam, M. Lakshmanan

Categories: cond-mat.other nlin.PS

Comments: 10 pages, 5 figures

\\ ( http://arxiv.org/abs/0902.0934 , 2121kb)

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arXiv:0904.1750

replaced with revised version Wed, 3 Jun 2009 18:53:27 GMT (17kb)

Title: The Yrast Line of a Rapidly Rotating Bose Gas: Gross-Pitaevskii Regime

Authors: Elliott H. Lieb, Robert Seiringer, Jakob Yngvason

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

Comments: RevTeX4, 9 pages; references added; to appear in Phys. Rev. A

\\ ( http://arxiv.org/abs/0904.1750 , 17kb)

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arXiv:0810.4982

replaced with revised version Thu, 4 Jun 2009 03:00:56 GMT (11kb)

Title: Feasibility of Experimental Realization of Entangled Bose-Einstein

Condensation

Authors: Yu Shi

Categories: cond-mat.other

Comments: 6 pages

\\ ( http://arxiv.org/abs/0810.4982 , 11kb)

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arXiv:0903.2796

replaced with revised version Thu, 4 Jun 2009 17:23:22 GMT (64kb)

Title: Cooling atoms into entangled states

Authors: Giovanni Vacanti and Almut Beige

Categories: quant-ph

Comments: 16 pages, 6 figures, minor corrections, references added

\\ ( http://arxiv.org/abs/0903.2796 , 64kb)

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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 ========================================================================= _______________________________________________ Matts-arxiv mailing list Matts-arxiv_at_lists.sps.uq.edu.auReceived on Fri Jul 10 2009 - 16:01:05 EST

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