# Matt's arXiv selection: week ending 6 March 2009

From: Matthew Davis <mdavis_at_physics.uq.edu.au>
Date: Tue, 19 May 2009 08:44:33 +1000

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

Dear subscribers,

We have Simon Haine to thank for this week's list. There are 18 new preprints
and 9 replacements:

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arXiv:0902.4707
Date: Thu, 26 Feb 2009 21:31:39 GMT (901kb)

Title: On-site correlations in optical lattices: band mixing to coupled quantum
Hall puddles
Authors: Kaden R. A. Hazzard and Erich J. Mueller (Cornell)
Categories: cond-mat.other
\\
We extend the standard Bose-Hubbard model to capture arbitrarily strong
on-site correlations. In addition to being important for quantitatively
modeling experiments, for example, with Rubidium atoms, these correlations must
be included to describe more exotic situations. Two such examples are when the
interactions are made large via a Feshbach resonance, or when each site rotates
rapidly, making a coupled array of quantum Hall puddles. Remarkably, even the
mean field approximation to our model includes all on-site correlations. We
describe how these on-site correlations manifest themselves in the system's
global properties: modifying the phase diagram and depleting the condensate.
\\ ( http://arxiv.org/abs/0902.4707 , 901kb)
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arXiv:0902.4734
Date: Fri, 27 Feb 2009 01:11:49 GMT (94kb)

Title: Ultracold Bosons with 3-Body Attractive Interactions in an Optical
Lattice
Authors: E. Fersino, B.A. Malomed, G. Mussardo, A. Trombettoni
Categories: cond-mat.stat-mech
Comments: Special issue of European Physical Journal B on the conference
"Theory of Quantum Gases and Quantum Coherence" held in Grenoble, 2008
\\
We study the effect of an optical lattice (OL) on the ground-state properties
of one-dimensional ultracold bosons with three-body attraction and two-body
repulsion, which are described by a cubic-quintic Gross-Pitaevskii equation
with a periodic potential. Without the OL and with a vanishing two-body
interaction term, soliton solutions of the Townes type are possible only at a
critical value of the three-body interaction strength, at which an infinite
degeneracy of the ground-state occurs; a repulsive two-body interaction makes
such localized solutions unstable. We show that the OL opens a stability window
around the critical point when the strength of the periodic potential is above
a critical threshold. We also consider the effect of an external parabolic
trap, studying how the stability of the solitons depends on matching between
minima of the periodic potential and the minimum of the parabolic trap.
\\ ( http://arxiv.org/abs/0902.4734 , 94kb)
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arXiv:0902.4746
Date: Fri, 27 Feb 2009 02:55:08 GMT (603kb)

Title: Massless Dirac Fermions in a Square Optical Lattice
Authors: Jing-Min Hou, Wen-Xing Yang, Xiong-Jun Liu
Categories: cond-mat.other
\\
We propose a novel scheme to simulate and observe massless Dirac fermions
with cold atoms in a square optical lattice. A U(1) adiabatic phase is created
by two laser beams for the tunneling of atoms between neighbor lattice sites.
Properly adjusting the tunneling phase, we find that the energy spectrum has
conical points in per Brillouin zone where band crossing occurs. Near these
crossing points the quasiparticles and quasiholes can be considered as massless
Dirac fermions. Furthermore, the anisotropic effects of massless Dirac fermions
are obtained in the present square lattice model. The Dirac fermions as well as
the anisotropic behaviors realizeded in our system can be experimentally
detected with the Bragg spectroscopy technique.
\\ ( http://arxiv.org/abs/0902.4746 , 603kb)
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arXiv:0902.4775
Date: Fri, 27 Feb 2009 09:15:26 GMT (39kb)

Title: Asymptotic solutions of a nonlinear diffusive equation in the framework
of $\kappa$-generalized statistical mechanics
Authors: T. Wada and A.M. Scarfone
Categories: cond-mat.stat-mech
\\
The asymptotic behavior of a nonlinear diffusive equation obtained in the
framework of the $\kappa$-generalized statistical mechanics is studied. The
analysis based on the classical Lie symmetry shows that the $\kappa$-Gaussian
function is not a scale invariant solution of the generalized diffusive
equation. Notwithstanding, several numerical simulations, with different
initial conditions, show that the solutions asymptotically approach to the
$\kappa$-Gaussian function. Simple argument based on a time-dependent
transformation performed on the related $\kappa$-generalized Fokker-Planck
equation, supports this conclusion.
\\ ( http://arxiv.org/abs/0902.4775 , 39kb)
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arXiv:0902.4792
Date: Fri, 27 Feb 2009 10:46:30 GMT (35kb)

Title: Population Dynamics of a Spin-1 Bose Gas Above the Bose-Einstein
Transition Temperature
Authors: Yuki Endo and Tetsuro Nikuni
Categories: cond-mat.other
\\
We study population dynamics of a trapped spin-1 Bose gas above the
Bose-Einstein transition temperature. Starting from the semiclassical kinetic
equation for a spin-1 gas, we derive a coupled rate equations for the
populations of internal states. Solving the rate equations, we discuss the
dynamical evolution of spin populations. We also estimate the characteristic
timescale in which the system reaches equilibrium. Finally, we briefly discuss
how the presence of the condensate will affect the population dynamics.
\\ ( http://arxiv.org/abs/0902.4792 , 35kb)
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arXiv:0902.4628 (*cross-listing*)
Date: Thu, 26 Feb 2009 16:40:16 GMT (8kb)

Title: Is it possible to stimulate nuclear alpha decay by superfluid helium?
Authors: A. L. Barabanov
Categories: nucl-th cond-mat.stat-mech nucl-ex
\\
It is suggested that superfluid helium (condensate of 4-He atoms) may
stimulate nuclear alpha decay in situation when alpha emitter moves through
superfluid helium, while the back-emitted alpha particle comes to rest. It is
shown that the probability of stimulated alpha decay may be sizable enough to
be detected.
\\ ( http://arxiv.org/abs/0902.4628 , 8kb)
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arXiv:0902.4898
Date: Fri, 27 Feb 2009 19:19:20 GMT (8kb)

Title: Effective Quantum Time Travel
Authors: George Svetlichny
Categories: quant-ph
\\
The quantum teleportation protocol can be used to probabilistically simulate
a quantum circuit with backward-in-time connections. This allows us to analyze
some conceptual problems of time travel in the context of physically realizable
situations, to realize encrypted measurements of future states for which the
decryption key becomes available only after the state is created, and to
probabilistically realize a multistage quantum state processing within the time
needed to complete only one stage. The probabilistic nature of the process
\\ ( http://arxiv.org/abs/0902.4898 , 8kb)
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arXiv:0902.4692 (*cross-listing*)
Date: Thu, 26 Feb 2009 20:33:23 GMT (287kb)

Title: The Tiger and the Sun: Solar Power Plants and Wildlife Sanctuaries
Authors: Michael McGuigan
Categories: q-bio.PE physics.soc-ph
Comments: 19 pages, 4 tables, 9 figures
\\
We discuss separate and integrated approaches to building scalable solar
power plants and wildlife sanctuaries. Both solar power plants and wildlife
sanctuaries need a lot of land. We quantify some of the requirements using
various estimates of the rate of solar power production as well as the rate of
adding wildlife to a sanctuary over the time range 2010-2050. We use population
dynamics equations to study the evolution of solar energy and tiger populations
up to and beyond 2050.
\\ ( http://arxiv.org/abs/0902.4692 , 287kb)
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arXiv:0903.0016
Date: Sat, 28 Feb 2009 09:09:00 GMT (59kb)

Title: Magnon BEC in superfluid 3He-A
Authors: Yu.M. Bunkov and G.E. Volovik
Categories: cond-mat.other cond-mat.dis-nn
Comments: 6 pages, 2 figures, JETP Letters style
\\
The new mode of magnetization precession in superfluid 3He-A in a squeezed
aerogel has been recently reported. We consider this mode in terms of the
Bose-Einstein condensation (BEC) of magnons. The difference between magnon BEC
states in 3He-A and in 3He-B is discussed.
\\ ( http://arxiv.org/abs/0903.0016 , 59kb)
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arXiv:0903.0108
Date: Sat, 28 Feb 2009 21:03:08 GMT (378kb)

Title: Accessing the Neel phase of ultracold fermionic atoms in a simple-cubic
optical lattice
Authors: C.J.M. Mathy, D.A. Huse
Categories: cond-mat.str-el
\\
We examine the phase diagram of a simple-cubic optical lattice half-filled by
two species of fermionic atoms with a repulsive s-wave contact interaction. We
use the Hartree approximation in the regime of weaker interactions, and a
Hubbard model approximation in the Mott insulating phase. The regime where the
Neel phase of this system is likely to be most accessible to experiments is at
intermediate lattice strengths and interactions, and our two approximations
agree fairly well in this regime. We discuss the various issues that may
determine where in this phase diagram the Neel phase is first produced and
detected experimentally, and analyze the quantum phases that occur in the
intermediate lattice strength regime.
\\ ( http://arxiv.org/abs/0903.0108 , 378kb)
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arXiv:0903.0146
Date: Sun, 1 Mar 2009 14:50:08 GMT (384kb)

Title: Stable Bloch oscillations of cold atoms with time dependent interaction
Authors: C. Gaul, R. P. A. Lima, E. Diaz, C. A. Mueller, and F. Dominguez-Adame
Categories: cond-mat.other
\\
We investigate Bloch oscillations of interacting cold atoms in a mean-field
framework. In general, atom-atom interaction causes dephasing and destroys
Bloch oscillations. Here, we show that Bloch oscillations are persistent if the
interaction is modulated harmonically with suitable frequency and phase. For
other modulations, Bloch oscillations are rapidly damped. We explain this
behavior in terms of collective coordinates whose Hamiltonian dynamics permits
to predict a whole family of stable solutions. In order to describe also the
unstable cases, we carry out a stability analysis for Bogoliubov excitations.
Using Floquet theory, we are able to predict the unstable modes as well as
their growth rate, found to be in excellent agreement with numerical
simulations.
\\ ( http://arxiv.org/abs/0903.0146 , 384kb)
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arXiv:0903.0151
Date: Sun, 1 Mar 2009 16:25:51 GMT (725kb)

Title: Dissipation-induced coherent structures in Bose-Einstein condensates
Authors: Valeriy A. Brazhnyi, Vladimir V. Konotop, Victor M. Perez-Garcia,
Herwig Ott
Categories: cond-mat.other
\\
We discuss how to engineer the phase and amplitude of a complex order
parameter using localized dissipative perturbations. Our results are applied to
generate and control various types of atomic nonlinear matter waves (solitons)
by means of localized dissipative defects.
\\ ( http://arxiv.org/abs/0903.0151 , 725kb)
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arXiv:0903.0260
Date: Mon, 2 Mar 2009 11:24:44 GMT (1569kb)

Title: Nonperturbative thermodynamics of an interacting Bose gas
Authors: S. Floerchinger and C. Wetterich
Categories: cond-mat.other
\\
We discuss the thermodynamics of a non-relativistic gas of bosons with a
local repulsive interaction. In particular, we compute the temperature and
density dependence of pressure, energy and entropy-density, superfluid and
condensate-fraction, correlation length, specific heat, isothermal and
adiabatic compressibility and various sound velocities. The T->0 limit
approaches the quantum phase transition, while the universal critical behavior
of a classical second order phase transition in the O(2) universality class
determines the region around the critical temperature. Our non-perturbative
flow equations based on exact functional renormalization cover all regions in
the phase diagram.
\\ ( http://arxiv.org/abs/0903.0260 , 1569kb)
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arXiv:0902.4725 (*cross-listing*)
Date: Thu, 26 Feb 2009 23:31:15 GMT (11kb)

Title: Mapping the Two-Component Atomic Fermi Gas to the Nuclear Shell-Model
Authors: C. \"Ozen and N.T. Zinner
Categories: nucl-th cond-mat.str-el
Comments: 7 pages, no figures. Revtex4
\\
The physics of two-component fermi systems is now frequently addressed in
laboratories. Usually this is done for large samples of tens to hundreds of
thousands of particles. However, there are now groups working towards few-body
systems (1-100 particles) in very tight traps where the shell structure of the
external potential becomes important. This is analogous to the situation
encountered in nuclear structure physics. Here the state-of-the-art method is
large-scale diagonalization of the interaction hamiltonian in an appropriate
model space. We map the atomic physics problem onto the nuclear shell-model and
show that the two-component atomic fermi gas with zero-range interaction does
not suffer from the famous fermionic sign problem, making Quantum Monte Carlo
methods feasible.
\\ ( http://arxiv.org/abs/0902.4725 , 11kb)
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arXiv:0903.0724
Date: Wed, 4 Mar 2009 10:39:55 GMT (1120kb,D)

Title: Coherent transport of atomic wave packets in amplitude-modulated optical
lattices under the effect of gravity
Authors: A. Alberti, G. Ferrari, V. V. Ivanov and G. M. Tino
Categories: quant-ph
\\
We report on the experimental realization of a dynamical control of transport
of ultra-cold atoms loaded in an accelerated and amplitude-modulated 1D optical
lattice potential. We tailor the dispersion law of traveling wave packets and
we show the ability to reversibly switch between localization regime and
tunneling one. From this we demonstrate a novel atom mirror in optical lattices
by reversing the group velocity of the atoms independently of their momentum
state. We discuss a direct application of this transport mechanism to measure
forces at micrometric spatial scales.
\\ ( http://arxiv.org/abs/0903.0724 , 1120kb)
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arXiv:0903.0968
Date: Thu, 5 Mar 2009 11:54:10 GMT (107kb)

Title: "Scars" in Bose-Einstein condensates?
Authors: Nadav Katz and Oded Agam
Categories: cond-mat.other
\\
Parametric excitation of a Bose-Einstein condensate (BEC) can be realized by
periodically changing the interaction strength between the atoms. Above
threshold, this excitation modulates the condensate density. We show that when
the condensate is trapped in a potential well of irregular shape, such as the
stadium billiard, the density waves can be strongly scarred along the shortest
periodic orbits of rays moving within the confining potential. However, while
single-particle wave functions of chaotic systems may exhibit rich scarring
patterns, we find that nonlinear effects in BEC hinder the excitation of long
scars. Scars are found to be unstable to dephasing. This property provides a
sensitive probe for measuring decoherence in BECs.
\\ ( http://arxiv.org/abs/0903.0968 , 107kb)
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arXiv:0903.0997
Date: Thu, 5 Mar 2009 14:10:09 GMT (9kb)

Title: New application of Dirac's representation: N-mode squeezing enhanced
operator and squeezed state
Authors: Xue-xiang Xu, Li-yun Hu and Hong-yi Fan
Categories: quant-ph
\\
It is known that exp[i\lamda(Q_1P_1-i/2)] is a unitary single-mode squeezing
operator, where Q_1,P_1 are the coordinate and momentum operators,
respectively. In this paper we employ Dirac's coordinate representation to
prove that the exponential operator S_{n}=Exp[i\lamda
sum_{i=1}^{n}](Q_{i}P_{i+1}+Q_{i+1}P_{i}))], (Q_{n+1}=Q_1P_{n+1}=P_1), is a
n-mode squeezing operator which enhances the standard squeezing. By virtue of
the technique of integration within an ordered product of operators we derive
S_{n}'s normally ordered expansion and obtain new n-mode squeezed vacuum
states, its Wigner function is calculated by using the Weyl ordering invariance
under similar transformations.
\\ ( http://arxiv.org/abs/0903.0997 , 9kb)
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arXiv:0903.0998 (*cross-listing*)
Date: Thu, 5 Mar 2009 02:32:14 GMT (25kb)

Title: Modification of spin mixing of spinor BEC by cavity QED coupling
Authors: Ma Luo, Chengguang Bao, Zhibing Li
Categories: physics.atm-clus physics.optics
\\
Dressed states of spinor Bose-Einstein condensates of spin-1 atoms coupling
with optical cavity modes with far off resonance frequency are investigated.
The exact solution of time evolution of population of spin component is
derived, and the numerical result shows that the evolution is different from
spin mixing without the coupling. Due to the coupling with the atoms, the
photon state also evolute to different optical cavity modes.
\\ ( http://arxiv.org/abs/0903.0998 , 25kb)
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The replacements:

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arXiv:0809.2387
replaced with revised version Fri, 27 Feb 2009 03:37:10 GMT (77kb)

Title: Absence of Anomalous Tunneling of Bogoliubov Excitations for Arbitrary
Potential Barrier under the Critical Condensate Current
Authors: Daisuke Takahashi and Yusuke Kato
Categories: cond-mat.other
Journal-ref: J. Phys. Soc. Jpn. 78, 023001 (2009)
DOI: 10.1143/JPSJ.78.023001
\\ ( http://arxiv.org/abs/0809.2387 , 77kb)
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arXiv:0812.1387
replaced with revised version Fri, 27 Feb 2009 13:25:58 GMT (355kb)

Title: Effective three-body interactions and decoherence of coherent atom
states in optical lattices
Authors: P.R. Johnson, E. Tiesinga, J.V. Porto, C.J. Williams
Categories: quant-ph
inhomogeneities on collapse and revival in contrast to effect of three-body
interactions
\\ ( http://arxiv.org/abs/0812.1387 , 355kb)
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arXiv:0902.4574 (*cross-listing*)
replaced with revised version Fri, 27 Feb 2009 14:11:26 GMT (413kb)

Title: Coherent state of the effective mass harmonic oscillator
Authors: Atreyee Biswas and Barnana Roy
Categories: math-ph math.MP quant-ph
Comments: 18 Pages, 5 Figures. To be published in Mod. Phys. Lett. A
\\ ( http://arxiv.org/abs/0902.4574 , 413kb)
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arXiv:cond-mat/0201217
replaced with revised version Mon, 2 Mar 2009 14:42:18 GMT (59kb)

Title: The truncated Wigner method for Bose condensed gases: limits of validity
and applications
Authors: Alice Sinatra, Carlos Lobo, Yvan Castin
Categories: cond-mat.stat-mech
Comments: 28 pages, 7 figures, typos corrected in Eqs.(85) and (91)
Journal-ref: J. Phys. B 35, 3599-3631 (2002)
\\ ( http://arxiv.org/abs/cond-mat/0201217 , 59kb)
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arXiv:0807.1433
replaced with revised version Sun, 1 Mar 2009 23:32:25 GMT (143kb)

Title: Non-Abelian magnetic monopole in a Bose-Einstein condensate
Authors: Ville Pietil\"a and Mikko M\"ott\"onen
Categories: cond-mat.other cond-mat.mes-hall
Comments: 5 pages, 1 color figure; v2 modified according to referees'
suggestions, some typos corrected; v3 minor modifications, published version
Journal-ref: Phys. Rev. Lett. 102, 080403 (2009)
\\ ( http://arxiv.org/abs/0807.1433 , 143kb)
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arXiv:0809.4419
replaced with revised version Mon, 2 Mar 2009 09:05:30 GMT (249kb)

Title: Fermionization of a strongly interacting Bose-Fermi mixture in a
one-dimensional harmonic trap
Authors: Bess Yiyuan Fang (University of Singapore), Patrizia Vignolo (INLN,
Nice, France), Christian Miniatura (University of Singapore and INLN, Nice,
France), Anna Minguzzi (LPMMC, Grenoble, France)
Categories: cond-mat.other
Comments: revised version; 8 pages, 7 figures
Journal-ref: Phys. Rev. A 79, 023623 (2009)
DOI: 10.1103/PhysRevA.79.023623
\\ ( http://arxiv.org/abs/0809.4419 , 249kb)
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arXiv:0806.3877
replaced with revised version Wed, 4 Mar 2009 09:31:36 GMT (1052kb,D)

Title: Optimizing number squeezing when splitting a mesoscopic condensate
Authors: Julian Grond, Joerg Schmiedmayer, Ulrich Hohenester
Categories: cond-mat.other
Comments: 4 pages, v3: minor changes
Journal-ref: Phys. Rev. A 79, 021603(R) (2009)
DOI: 10.1103/PhysRevA.79.021603
\\ ( http://arxiv.org/abs/0806.3877 , 1052kb)
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arXiv:0807.0572
replaced with revised version Thu, 5 Mar 2009 16:38:47 GMT (326kb)

Title: Probing the thermal atoms of a Bose gas through Raman transition
Authors: Patrick Navez
Categories: cond-mat.other
Comments: 18 pages, 6 figures, Topical Issue on Novel Quantum Phases and
Mesoscopic Physics in Quantum Gases
DOI: 10.1140/epjb/e2009-00073-y
\\ ( http://arxiv.org/abs/0807.0572 , 326kb)
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arXiv:0901.2755
replaced with revised version Thu, 5 Mar 2009 20:54:18 GMT (454kb)

Title: Scale invariant thermodynamics of a toroidally trapped Bose gas
Categories: cond-mat.stat-mech
Comments: 10 pages, 3 figures, to appear in Phys. Rev. A, typos corrected,
references added, rewritten to emphasize generalized volume. Results
unchanged
\\ ( http://arxiv.org/abs/0901.2755 , 454kb)
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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/
=========================================================================
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Received on Tue May 19 2009 - 11:49:23 EST

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