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

Date: Tue, 08 Jan 2008 09:27:27 +1000

Date: Tue, 08 Jan 2008 09:27:27 +1000

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

Hi all,

I'm off to a good start this year... it was a quiet week with only 15 new

preprints and 5 replacements... and even then a couple of them aren't actually

relevant to cold atoms but caught my eye anyway.

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arXiv:0712.4284

Date: Thu, 27 Dec 2007 21:29:46 GMT (493kb)

Title: The $p_{x,y}$-orbital counterpart of graphene: cold atoms in the

honeycomb optical lattice

Authors: Congjun Wu and S. Das Sarma

Categories: cond-mat.str-el cond-mat.mtrl-sci

\\

We study the ground state properties of the interacting spinless fermions in

the $p_{x,y}$-orbital bands in the two dimensional honeycomb optical lattice,

which exhibit different novel features from those in the $p_z$-orbital system

of graphene. In addition to two dispersive bands with Dirac cones, the

tight-binding band structure exhibits another two completely flat bands over

the entire Brillouin zone. With the realistic sinusoidal optical potential, the

flat bands acquire a finite but much smaller band width compared to the

dispersive bands. The band flatness dramatically enhanced interaction effects

giving rise to various charge and bond ordered states at commensurate fillings

of $n=\frac{i}{6} (i=1 \sim 6)$. At $n=1/6$, the many-body ground states can be

exactly solved as the close packed hexagon states which can be stabilized even

in the weak interacting regime. The dimerization of bonding strength occurs at

both $n=1/2$ and 5/6, and the latter case is accompanied with the charge

density wave of holes. The trimerization of bonding strength and charge

inhomogeneity appear at $n={1/3},{2/3}$. These crystalline orders exhibit

themselves in the noise correlations of the time of flight spectra.

\\ ( http://arxiv.org/abs/0712.4284 , 493kb)

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arXiv:0801.0009

Date: Fri, 28 Dec 2007 22:02:12 GMT (317kb,D)

Title: Non Perturbative Renormalization Group and Bose-Einstein Condensation

Authors: Jean-Paul Blaizot

Categories: cond-mat.stat-mech

Comments: Lectures given at the 2006 ECT* School "Renormalization Group and

Effective Field Theory Approaches to Many-Body Systems", Trento, Italy. Late

submission to arXiv

\\

These lectures are centered around a specific problem, the effect of weak

repulsive interactions on the transition temperature $T_c$ of a Bose gas. This

problem provides indeed a beautiful illustration of many of the techniques

which have been discussed at this school on effective theories and

renormalization group. Effective theories are used first in order to obtain a

simple hamiltonian describing the atomic interactions: because the typical

atomic interaction potentials are short range, and the systems that we consider

are dilute, these potentials can be replaced by a contact interaction whose

strength is determined by the s-wave scattering length. Effective theories are

used next in order to obtain a simple formula for the shift in $T_c$: one

exploits there the fact that near $T_c$ the physics is dominated by low

momentum modes whose dynamics is most economically described in terms of

classical fields; the ingredients needed to calculate the shift of $T_c$ can be

obtained from this classical field theory. Finally the renormalization group is

used both to obtain a qualitative understanding, and also as a non perturbative

tool to evaluate quantitatively the shift in $T_c$.

\\ ( http://arxiv.org/abs/0801.0009 , 317kb)

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arXiv:0801.0020

Date: Sat, 29 Dec 2007 01:26:48 GMT (96kb)

Title: Intrinsic relation between ground state fidelity and the

characterization of a quantum phase transition

Authors: Shu Chen, Li Wang, Yajiang Hao, Yupeng Wang

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

Comments: 4 pages, 3 figures

\\

The notion of fidelity in quantum information science has been recently

applied to analyze quantum phase transitions from the viewpoint of the ground

state (GS) overlap for various many-body systems. In this work, we unveil the

intrinsic relation between the GS fidelity and the derivatives of GS energy and

find that they play equivalent role in identifying the quantum phase

transition. The general connection between the two approaches enables us to

understand the different singularity and scaling behaviors of fidelity

exhibited in various systems on general grounds. Our general conclusions are

illustrated via several quantum spin models which exhibit different kinds of

QPTs.

\\ ( http://arxiv.org/abs/0801.0020 , 96kb)

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arXiv:0801.0150

Date: Sun, 30 Dec 2007 18:02:15 GMT (164kb)

Title: Effects of strong correlations for 2D Bose-Einstein condensed dipolar

excitons

Authors: Yu. E. Lozovik, I. L. Kurbakov, G. E. Astrakharchik, J. Boronat, M.

Willander

Categories: cond-mat.str-el

Journal-ref: Sol.St.Comms., 144, 399-404 (2007)

\\

By doing quantum Monte Carlo ab initio simulations we show that dipolar

excitons, which are now under experimental study, actually are strongly

correlated systems. Strong correlations manifest in significant deviations of

excitation spectra from the Bogoliubov one, large Bose condensate depletion,

short-range order in the pair correlation function, and peak(s) in the

structure factor.

\\ ( http://arxiv.org/abs/0801.0150 , 164kb)

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arXiv:0801.0152

Date: Sun, 30 Dec 2007 18:06:09 GMT (75kb)

Title: Superfluidity of two- dimensional excitons in flat and harmonic traps

Authors: Yu. E. Lozovik, I. L. Kurbakov, M. Willander

Categories: cond-mat.str-el

Journal-ref: Phys. Lett. A 366, No. 4-5, 487-492 (2007)

\\

Superfluid exciton density and superfluid transition (crossover) temperature

are calculated for 2D excitons in large-size flat and harmonic traps. A

generalized local density approximation for the Kosterlitz-Thouless theory is

developed.

\\ ( http://arxiv.org/abs/0801.0152 , 75kb)

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arXiv:0801.0383

Date: Wed, 2 Jan 2008 13:44:40 GMT (424kb)

Title: Vortex-lattice formation and melting in a nonrotating Bose-Einstein

Condensate

Authors: Gary Ruben, David M. Paganin, and Michael J. Morgan (School of

Physics, Monash University)

Categories: cond-mat.other

Comments: 9 pages, 7 figures, REVTeX4

\\

Numerical simulations of the interference of a three-way segmented

nonrotating Bose-Einstein Condensate reveal the production of a honeycomb

vortex lattice containing significant numbers of vortices and antivortices

which, if confined within a trap, interact in complex ways over time. In

contrast with nonlinear vortex production mechanisms previously described for

BECs, the process here is primarily one of linear superposition, with initial

vortex locations described by a linear theory of wave packet interference. The

subsequent interaction dynamics, involving a rich vortex-antivortex chemistry,

reveal a phase transition from an ordered to a disordered state.

\\ ( http://arxiv.org/abs/0801.0383 , 424kb)

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arXiv:0801.0119

Date: Sun, 30 Dec 2007 09:59:27 GMT (627kb)

Title: Spectrum of coherently backscattered light from two atoms

Authors: Vyacheslav Shatokhin, Thomas Wellens, Beno\^it Gr\'emaud, Andreas

Buchleitner

Categories: quant-ph

Comments: 14 pages, 9 figures

Journal-ref: Phys. Rev. A 76, 043832 (2007)

\\

We present a detailed analytical and numerical analysis of the inelastic

coherent backscattering spectrum of laser light incident on cold atoms. We

identify frequency domains where the interference contribution can be positive

\emph{as well as} negative -- or exhibits dispersive character. These

distinctive features are explained by reciprocity arguments and dressed state

two-photon scattering amplitudes.

\\ ( http://arxiv.org/abs/0801.0119 , 627kb)

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arXiv:0801.0405

Date: Wed, 2 Jan 2008 15:17:10 GMT (610kb,D)

Title: Atoms in a radiofrequency-dressed optical lattice

Authors: N. Lundblad, P. J. Lee, I. B. Spielman, B. L. Brown, W. D. Phillips,

and J. V. Porto

Categories: quant-ph

Comments: 5 pages, 4 figures

\\

We load cold atoms into an optical lattice dramatically reshaped by

radiofrequency (rf) coupling of state-dependent lattice potentials. This rf

dressing changes the unit cell of the lattice at a subwavelength scale, such

that its curvature and topology departs strongly from that of a simple

sinusoidal lattice potential. Radiofrequency dressing has previously been

performed at length scales from mm to tens of microns, but not at the

single-optical-wavelength scale. At this length scale significant coupling

between adiabatic potentials leads to nonadiabatic transitions, which we

measure as a function of lattice depth and dressing frequency and amplitude. We

also investigate the dressing by measuring changes in the momentum distribution

of the dressed states.

\\ ( http://arxiv.org/abs/0801.0405 , 610kb)

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arXiv:0801.0028

Date: Sat, 29 Dec 2007 02:39:17 GMT (456kb)

Title: CODATA Recommended Values of the Fundamental Physical Constants: 2006

Authors: Peter J. Mohr, Barry N. Taylor, and David B. Newell

Categories: physics.atom-ph physics.gen-ph

Comments: 105 pages, 7 figures, 46 tables; describes in detail the 2006 CODATA

adjustment of the values of the constants

\\

This paper gives the 2006 self-consistent set of the basic constants and

conversion factors of physics and chemistry recommended by the Committee on

Data for Science and Technology (CODATA) for international use. Further, it

describes in detail the adjustment of the values of the constants, including

the selection of the final set of input data based on the results of

least-squares analyses. The 2006 adjustment takes into account the data

considered in the 2002 adjustment as well as the data that became available

between 31 December 2002, the closing date of that adjustment, and 31 December

2006, the closing date of the new adjustment. The new data have led to a

significant reduction in the uncertainties of many recommended values. The 2006

set replaces the previously recommended 2002 CODATA set and also may be found

on the World Wide Web at physics.nist.gov/constants.

\\ ( http://arxiv.org/abs/0801.0028 , 456kb)

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arXiv:0801.0589

Date: Thu, 3 Jan 2008 20:54:15 GMT (44kb)

Title: Orbital order in Mott insulators of spinless p-band fermions

Authors: Erhai Zhao and W. Vincent Liu

Categories: cond-mat.str-el cond-mat.other

Comments: 3 figures

\\

A gas of strongly interacting spinless p-orbital fermionic atoms in 2D

optical lattices is proposed and studied. Several interesting new features are

found. In the Mott limit on a square lattice, the gas is found to be described

effectively by an orbital exchange Hamiltonian equivalent to a pseudospin-1/2

XXZ model. For a triangular, honeycomb, or Kagome lattice, the orbital exchange

is geometrically frustrated and described by a new quantum 120 degree model. We

determine the orbital orderings on each lattice, and show how orbital wave

fluctuations select ground states via the order by disorder mechanism for the

honeycomb and triangular lattice. We discuss experimental signatures of various

orbital ordering.

\\ ( http://arxiv.org/abs/0801.0589 , 44kb)

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arXiv:0801.0132 (*cross-listing*)

Date: Sun, 30 Dec 2007 15:47:47 GMT (25kb)

Title: Exact diagonalisation of 1-d interacting spinless Fermions

Authors: Heiner Kohler

Categories: math-ph cond-mat.str-el math.MP

Comments: 30 pages

MSC-class: 37K10; 37K15

\\

A new method of constructing an infinite set of exact eigenfunctions of 1-d

interacting spinless Fermionic systems is derived. Creation and annihilation

operators for the interacting system are found and thereby the many-body

Hamiltonian is diagonalised. The formalism is applied to several examples. One

instance is the theory of Jack polynomials. For the Calogero-Moser-Sutherland

Hamiltonian a direct proof of the correctness of the asymptotic Bethe Ansatz is

given.

\\ ( http://arxiv.org/abs/0801.0132 , 25kb)

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arXiv:0801.0577

Date: Thu, 3 Jan 2008 19:16:20 GMT (999kb,D)

Title: Magnetically-controlled velocity selection in a cold atom sample using

stimulated Raman transitions

Authors: Matthew L. Terraciano, Spencer E. Olson, Mark Bashkansky, Zachary

Dutton, Fredrik K. Fatemi

Categories: quant-ph

Comments: 5 pages, 6 figures

Journal-ref: Physical Review A 76, 053421 (2007)

DOI: 10.1103/PhysRevA.76.053421

\\

We observe velocity-selective two-photon resonances in a cold atom cloud in

the presence of a magnetic field. We use these resonances to demonstrate a

simple magnetometer with sub-mG resolution. The technique is particularly

useful for zeroing the magnetic field and does not require any additional laser

frequencies than are already used for standard magneto-optical traps. We verify

the effects using Faraday rotation spectroscopy.

\\ ( http://arxiv.org/abs/0801.0577 , 999kb)

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arXiv:0801.0475

Date: Thu, 3 Jan 2008 04:37:32 GMT (290kb)

Title: Observation of coherence revival and fidelity saturation in a

delta-kicked rotor potential

Authors: Saijun Wu, Alexey Tonyushkin, Mara G. Prentiss

Categories: physics.atom-ph physics.gen-ph

Comments: 10 pages, 3 figures

\\

We experimentally investigate the effect of atomic delta-kicked rotor

potentials on the mutual coherence between wavepackets in an atom

interferometer. The differential action of the kicked rotor degrades the mutual

coherence, leading to a reduction of the interferometry fringe visibility;

however, when the repetition rate of the kicked rotor is at or near the quantum

resonance, we observe revival of matter-wave coherence as the number of kicks

increases, resulting in non-vanishing coherence in the large kick number limit.

This coherence saturation effect reflects a fidelity saturation in phase-space

displacement echoes in deep quantum regime. The saturation effect is

accompanied with an invariant distribution of matter-wave coherence under the

kicked rotor perturbations.

\\ ( http://arxiv.org/abs/0801.0475 , 290kb)

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arXiv:0801.0524

Date: Thu, 3 Jan 2008 13:41:05 GMT (263kb)

Title: Self-citation as an impact-reinforcing mechanism in the science system

Authors: Anthony F.J. van Raan

Categories: physics.soc-ph physics.data-an

Comments: 22 pages, 18 figures, 4 tables

\\

In previous papers it was demonstrated that lower performance groups have a

larger size-dependent cumulative advantage for receiving citations than

top-performance groups. Furthermore, regardless of performance, larger groups

have less not-cited publications. Particularly for the lower performance groups

the fraction of not-cited publications decreases considerably with size. These

phenomena can be explained with a model in which self-citation acts as a

promotion mechanism for external citations. In this article we show that for

self-citations similar size-dependent scaling rules apply as for citations but

generally the power law exponents are higher for self-citations as compared to

citations. We also find that the fraction of self-citations is smaller for the

higher performance groups and this fraction decreases more rapidly with

increasing journal impact than for lower performance groups. An interesting

novel finding is that the variance in the correlation of the number of

self-citations with size is considerably less than the variance for external

citations. This is a clear indication that size is a stronger determinant for

self-citations than for external citations. Both higher and particularly lower

performance groups have a size-dependent cumulative advantage for

self-citations, but for the higher performance groups only in the lower impact

journals and in fields with low citation density.

\\ ( http://arxiv.org/abs/0801.0524 , 263kb)

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arXiv:0801.0253 (*cross-listing*)

Date: Mon, 31 Dec 2007 23:51:51 GMT (230kb,D)

Title: Toward a statistical mechanics of four letter words

Authors: Greg J. Stephens and William Bialek

Categories: q-bio.NC cs.CL physics.data-an physics.soc-ph

\\

We consider words as a network of interacting letters, and approximate the

probability distribution of states taken on by this network. Despite the

intuition that the rules of English spelling are highly combinatorial (and

arbitrary), we find that maximum entropy models consistent with pairwise

correlations among letters provide a surprisingly good approximation to the

full statistics of four letter words, capturing ~92% of the multi-information

among letters and even "discovering" real words that were not represented in

the data from which the pairwise correlations were estimated. The maximum

entropy model defines an energy landscape on the space of possible words, and

local minima in this landscape account for nearly two-thirds of words used in

written English.

\\ ( http://arxiv.org/abs/0801.0253 , 230kb)

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The replacements:

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arXiv:cond-mat/0702183

replaced with revised version Fri, 28 Dec 2007 14:18:46 GMT (516kb)

Title: Coherent Matter Wave Transport in Speckle Potentials

Authors: R.C. Kuhn, O. Sigwarth, C. Miniatura, D. Delande, C.A. Mueller

Categories: cond-mat.other

Comments: 33 pages, minor corrections, published version

Journal-ref: New J. Phys. 9 (2007) 161

DOI: 10.1088/1367-2630/9/6/161

\\ ( http://arxiv.org/abs/cond-mat/0702183 , 516kb)

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arXiv:0708.3039

replaced with revised version Fri, 28 Dec 2007 18:36:17 GMT (279kb)

Title: Exact Solution of Strongly Interacting Quasi One-Dimensional Spinor Bose

Gases

Authors: Frank Deuretzbacher, Klaus Fredenhagen, Daniel Becker, Kai Bongs,

Klaus Sengstock, Daniela Pfannkuche

Categories: cond-mat.other

Comments: Revised to discuss large but finite interactions

\\ ( http://arxiv.org/abs/0708.3039 , 279kb)

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\

arXiv:0707.4172

replaced with revised version Wed, 2 Jan 2008 17:48:26 GMT (102kb)

Title: Pairing states of a polarized Fermi gas trapped in a one-dimensional

optical lattice

Authors: A.E. Feiguin, and F. Heidrich-Meisner

Categories: cond-mat.str-el cond-mat.supr-con

Comments: 4 pages, 5 figs

Journal-ref: Phys. Rev. B 76, 220508(R) (2007)

DOI: 10.1103/PhysRevB.76.220508

\\ ( http://arxiv.org/abs/0707.4172 , 102kb)

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arXiv:0712.0205 (*cross-listing*)

replaced with revised version Sun, 30 Dec 2007 13:12:46 GMT (12kb)

Title: Self-consistent equations of unitary fermion thermodynamics with elusive

non-Gaussian correlations

Authors: Ji-sheng Chen, Jia-rong Li, Yan-ping Wang, Xiang-jun Xia

Categories: cond-mat.stat-mech hep-ph nucl-th quant-ph

Comments: Improved version with typos corrected

\\ ( http://arxiv.org/abs/0712.0205 , 12kb)

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arXiv:0707.0379

replaced with revised version Sun, 30 Dec 2007 21:49:38 GMT (228kb)

Title: Dependence of Resonant Absorption Linewidth on Atomic Vapour Column

Thickness for D1 Line of Cs Atoms Confined in Nano-Cell

Authors: A. Sargsyan, D. Sarkisyan, Y. Pashayan-Leroy, C. Leroy, P. Moroshkin,

A. Weis

Categories: physics.atom-ph

Comments: 13 pages

\\ ( http://arxiv.org/abs/0707.0379 , 228kb)

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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 Tue Jan 08 2008 - 10:01:09 EST

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