Matt's arXiv selection: week ending 13 March 2009

From: Matthew Davis <>
Date: Wed, 20 May 2009 16:57:41 +1000

The following message was sent to the matts_arxiv list by Matthew Davis <>

Dear subscribers,

Mike Garrett deserves our thanks for preparing this week's arXiv selection.
There are 34 new preprints and 17 replacements:

Date: Fri, 6 Mar 2009 18:06:33 GMT (1356kb)

Title: Intrinsic and dislocation induced elastic behavior of solid helium
Authors: James Day, Oleksandr Syshchenko, and John Beamish
Categories: cond-mat.other
   Recent experiments showed that the shear modulus of solid 4He stiffens in the
same temperature range (below 200 mK) where mass decoupling and supersolidity
have been inferred from torsional oscillator measurements. The two phenomena
are clearly related and crystal defects, particularly dislocations, appear to
be involved in both. We have studied the effects of annealing and the effects
of applying large stresses on the elastic properties of solid 4He, using both
acoustic resonances and direct low-frequency and low-amplitude measurements of
the shear modulus. Both annealing and stressing affect the shear modulus, as
expected if dislocations are responsible. However, it is the high temperature
modulus which is affected; the low temperature behavior is unchanged and
appears to reflect the intrinsic modulus of solid helium. We interpret this
behavior in terms of dislocations which are pinned by isotopic 3He impurities
at low temperatures and so have no effect on the shear modulus. At higher
temperatures they become mobile and weaken the solid. Stressing the crystal at
low temperatures appears to introduce new defects or additional pinning sites
for the dislocation network but these effects can be reversed by heating the
crystal above 500 mK. This is in contrast to dislocations produced during
crystal growth, which are only annealed at temperatures close to melting.
\\ ( , 1356kb)
Date: Fri, 6 Mar 2009 18:50:14 GMT (1126kb)

Title: Evidence for universal four-body states tied to an Efimov trimer
Authors: F. Ferlaino, S. Knoop, M. Berninger, W. Harm, J. P. D'Incao, H.-C.
   N\"agerl, and R. Grimm
Categories: cond-mat.other
Comments: 4 pages, 4 figures
   We report on the measurement of four-body recombination rate coefficients in
an atomic gas. Our results obtained with an ultracold sample of cesium atoms at
negative scattering lengths show a resonant enhancement of losses and provide
strong evidence for the existence of a pair of four-body states, which is
strictly connected to Efimov trimers via universal relations. Our findings
confirm recent theoretical predictions and demonstrate the enrichment of the
Efimov scenario when a fourth particle is added to the generic three-body
\\ ( , 1126kb)
Date: Fri, 6 Mar 2009 08:10:33 GMT (58kb)

Title: Testing General Relativity with Atomic Clocks
Authors: S. Reynaud, C. Salomon and P. Wolf
Categories: quant-ph gr-qc
Comments: Contribution for "The Nature of Gravity" (eds. F. Everitt et al)
   We discuss perspectives for new tests of general relativity which are based
on recent technological developments as well as new ideas. We focus our
attention on tests performed with atomic clocks and do not repeat arguments
present in the other contributions to the present volume. In particular, we
present the scientific motivations of the space projects ACES and SAGAS.
\\ ( , 58kb)
Date: Fri, 6 Mar 2009 13:55:15 GMT (50kb)

Title: Generation of entangled coherent states for distant Bose-Einstein
   condensates via electromagnetically induced transparency
Authors: Le-Man Kuang, Zeng-Bing Chen, and Jian-Wei Pan
Categories: quant-ph
Comments: 15 pages, 3 figures
Journal-ref: Phys. Rev. A 76, 052324 (2007)
   In this paper, we propose a method to generate entangled coherent states
between two spatially separated atomic Bose-Einstein condensates (BECs) via the
technique of the electromagnetically induced transparency (EIT). Two strong
coupling laser beams and two entangled probe laser beams are used to make two
distant BECs be in EIT states and to generate an atom-photon entangled state
between probe lasers and distant BECs. The two BECs are initially in
un-entangled product coherent states while the probe lasers are initially in an
entangled state. Entangled states of two distant BECs can be created through
performing projective measurements upon the two outgoing probe lasers under
certain conditions. Concretely, we propose two protocols to show how to
generate entangled coherent states of the two distant BECs. One is a
single-photon scheme in which an entangled single-photon state serves the
quantum channel to generate entangled distant BECs. The other is a multiphoton
scheme where an entangled coherent state of the probe lasers is used as the
quantum channel. Additionally, we also obtain some atom-photon entangled states
of particular interest such as entangled states between a pair of optical Bell
(or quasi-Bell) states and a pair of atomic entangled coherent (or quasi-Bell)
\\ ( , 50kb)
arXiv:0903.0895 s
Date: Thu, 5 Mar 2009 16:04:41 GMT (654kb)

Title: Quantum Quench from a Thermal Initial State
Authors: Spyros Sotiriadis, Pasquale Calabrese, John Cardy
Categories: cond-mat.stat-mech quant-ph
Comments: 8 pages, 3 figures
   We consider a quantum quench in a system of free bosons, starting from a
thermal initial state. As in the case where the system is initially in the
ground state, any finite subsystem eventually reaches a stationary thermal
state with a momentum-dependent effective temperature. Remarkably enough, we
find that this can, in some cases, even be lower than the initial temperature.
We also study lattice effects and discuss more general types of quenches.
\\ ( , 654kb)
Date: Fri, 6 Mar 2009 15:08:36 GMT (655kb)

Title: Molecular vibrational cooling by Optical Pumping with shaped femtosecond
Authors: Dimitris Sofikitis (LAC), Sebastien Weber (LCAR), Andr\'ea Fioretti
   (LAC), Ridha Horchani (LAC), Maria Allegrini (LAC, CNISM), B\'eatrice Chatel
   (LCAR), Daniel Comparat (LAC), Pierre Pillet (LAC)
Categories: physics.atom-ph
Comments: TO be published in New Journal of Physics
   Some of us have recently reported in Science 321 232 (2008) vibrational
cooling of translationally cold Cs_2 molecules into the lowest vibrational
level v=0 of the singlet X 1Sigma_g ground electronic state. Starting from a
sample of cold molecules produced in a collection of vibrational levels of the
ground state, our method was based on repeated optical pumping by laser light
with a spectrum broad enough to excite all populated vibrational levels but
frequency-limited in such a way to eliminate transitions from v=0 level, in
which molecules accumulate. In this paper this method is generalized to
accumulate molecules into an arbitrary selected "target" vibrational level. It
is implemented by using ultrashort pulse shaping techniques based on Liquid
Crystal spatial light modulator. In particular a large fraction of the
initially present molecule is transferred into a selected vibrational level
such as v=1, 2 and 7. Limitations of the method as well as the possible
extension to rotational cooling are also discussed.
\\ ( , 655kb)
Date: Fri, 6 Mar 2009 08:02:16 GMT (7kb)

Title: Dark states of dressed spinor Bose-Einstein condensates of spin-1 atoms
Authors: Ma Luo, Chengguang Bao, Zhibing Li
Categories: physics.atm-clus physics.optics
Comments: 4 pages
   Dressed states of spinor Bose-Einstein condensates of spin-1 atoms located in
optical cavity of near resonance frequency of excited state of the atom are
investigated. The wave function of dark states are given.
\\ ( , 7kb)
Date: Fri, 6 Mar 2009 22:43:54 GMT (333kb)

Title: Simulation of complete many-body quantum dynamics using controlled
   quantum-semiclassical hybrids
Authors: Piotr Deuar
Categories: cond-mat.other
Comments: 4+4 pages, 10 figures
   A controlled hybridization between full quantum dynamics and semiclassical
approaches (mean-field and truncated Wigner) is implemented for interacting
many-boson systems. One obtains continuous families of evolution equations that
interpolate smoothly between the (exact) positive-P representation and the
other incomplete treatments. It is then demonstrated how simulating these
hybrid equations allows one to obtain the full quantum dynamics for much longer
times than is possible using the exact treatment directly. This is demonstrated
on the realistic case of a collision of sodium BECs with 1.5x10^5 atoms. The
uncertainty of physical quantities remains well characterised because no ad-hoc
cutoffs are introduced in the description of the system. Extension to other
physical systems is discussed.
\\ ( , 333kb)
Date: Sat, 7 Mar 2009 06:38:51 GMT (353kb)

Title: Possible vortex fluid to supersolid transition in solid $^4$He below
   about 75 mK
Authors: Andrey Penzev, Nobutaka Shimizu, Yoshinori Yasuta, and Minoru Kubota
Categories: cond-mat.other
Comments: 4 pages, 5 figures
   A detailed torsional oscillator (TO) study on a stable solid 4He sample at 49
bar with To = 0.5K, is reported to T below the dissipation peak at Tp . We find
hysteretic behavior starting below Tc = about 75 mK, in period shift, as well
as in dissipation, with changes of AC excitation amplitude Vac . The derived
difference of non-linear rotational susceptibility DeltaNLRS(T)hys across the
hysteresis loop under a systematic condition is analyzed as a function of Vac
and T . We propose that DeltaN LRS(T)hys is proportional to non- classical
rortational inertia fraction, NCRIF, and is actually the supersolid density
rho_ss of the 3D supersolid state below Tc . rho_ss changes linearly with T
down to about 60 mK and then increases much more steeply, and approaching a
finite value towards T = 0. We find an AC velocity of 40 micrometer/s beyond
which the hysteresis starts at T < Tc and a critical AC velocity, about 1 cm/s,
above which rho_ss is completely destroyed. We discuss also the coherence
length of the supersolid.
\\ ( , 353kb)
Date: Mon, 9 Mar 2009 05:10:20 GMT (690kb)

Title: A simple mathematical proof of Boltzmann's equal a priori probability
Authors: Denis J. Evans, Debra J. Searles and Stephen R. Williams
Categories: cond-mat.stat-mech
Comments: 12 pages
   Using the Fluctuation Theorem (FT), we give a first-principles derivation of
Boltzmann's postulate of equal a priori probability in phase space for the
microcanonical ensemble. Using a corollary of the Fluctuation Theorem, namely
the Second Law Inequality, we show that if the initial distribution differs
from the uniform distribution over the energy hypersurface, then under very
wide and commonly satisfied conditions, the initial distribution will relax to
that uniform distribution. This result is somewhat analogous to the Boltzmann
H-theorem but unlike that theorem, applies to dense fluids as well as dilute
gases and also permits a nonmonotonic relaxation to equilibrium. We also prove
that in ergodic systems the uniform (microcanonical) distribution is the only
stationary, dissipationless distribution for the constant energy ensemble.
\\ ( , 690kb)
Date: Mon, 9 Mar 2009 15:30:25 GMT (1416kb)

Title: Coexisting Non-Equilibrium Condensates with Long-Range Spatial Coherence
   in Semiconductor Microcavities
Authors: D. N. Krizhanovskii, K. G. Lagoudakis, M. Wouters, B. Pietka, R. A.
   Bradley, K. Guda, D. M. Whittaker, M. S. Skolnick, B. Deveaud-Pledran, M.
   Richard, R. Andre, Le Si Dang
Categories: cond-mat.other
Comments: 9 pages, 12 figures
   Real and momentum space spectrally resolved images of microcavity polariton
emission in the regime of condensation are investigated under non resonant
excitation using a laser source with reduced intensity fluctuations on the
timescale of the exciton lifetime. We observe that the polariton emission
consists of many macroscopically occupied modes. Lower energy modes are
strongly localized by the photonic potential disorder on a scale of few
microns. Higher energy modes have finite k-vectors and are delocalized over
10-15 microns. All the modes exhibit long range spatial coherence comparable to
their size. We provide a theoretical model describing the behavior of the
system with the results of the simulations in good agreement with the
experimental observations. We show that the multimode emission of the polariton
condensate is a result of its nonequilibrium character, the interaction with
the local photonic potential and the reduced intensity fluctuations of the
excitation laser.
\\ ( , 1416kb)
Date: Mon, 9 Mar 2009 16:42:54 GMT (1486kb)

Title: Thermal and quantum fluctuations in chains of ultracold polar molecules
Authors: G. E. Astrakharchik, Gabriele De Chiara, Giovanna Morigi, and Jordi
Categories: cond-mat.mes-hall
Comments: to appear in Special issue on modern applications of trapped ions, J.
   Phys. B: At. Mol. Opt. Phys
   Ultracold polar molecules, in highly anisotropic traps and interacting via a
repulsive dipolar potential, may form one-dimensional chains at high densities.
According to classical theory, at low temperatures there exists a critical
value of the density at which a second order phase transition from a linear to
a zigzag chain occurs. We study the effect of thermal and quantum fluctuations
on these self-organized structures using classical and quantum Monte Carlo
methods, by means of which we evaluate the pair correlation function and the
static structure factor. Depending on the parameters, these functions exhibit
properties typical of a crystalline or of a liquid system. We compare the
thermal and the quantum results, identifying analogies and differences.
Finally, we discuss experimental parameter regimes where the effects of quantum
fluctuations on the linear - zigzag transition can be observed.
\\ ( , 1486kb)
Date: Mon, 9 Mar 2009 18:38:11 GMT (42kb)

Title: Susceptibility Propagation for Constraint Satisfaction Problems
Authors: Saburo Higuchi and Marc M\'ezard
Categories: cond-mat.dis-nn cond-mat.stat-mech
Comments: 17 pages, 5 figures
   We study the susceptibility propagation, a message-passing algorithm to
compute correlation functions. It is applied to constraint satisfaction
problems and its accuracy is examined. As a heuristic method to find a
satisfying assignment, we propose susceptibility-guided decimation where
correlations among the variables play an important role. We apply this novel
decimation to locked occupation problems, a class of hard constraint
satisfaction problems exhibited recently. It is shown that the present method
performs better than the standard belief-guided decimation.
\\ ( , 42kb)
Date: Sun, 8 Mar 2009 21:27:32 GMT (2197kb)

Title: Electromagnetically induced transparency controlled by a microwave field
Authors: Hebin Li, Vladimir A. Sautenkov, Yuri V. Rostovtsev, George R. Welch,
   Philip R. Hemmer, and Marlan O. Scully
Categories: quant-ph
Comments: 7 pages, 6 figures
   We have experimentally studied propagation of two optical fields in a dense
rubidium (Rb) vapor in the case when an additional microwave field is coupled
to the hyperfine levels of Rb atoms. The Rb energy levels form a close-lambda
three-level system coupled to the optical fields and the microwave field. It
has been found that the maximum transmission of a probe field depends on the
relative phase between the optical and the microwave fields. We have observed
both constructive and destructive interference in electromagnetically induced
transparency (EIT). A simple theoretical model and a numerical simulation have
been developed to explain the observed experimental results.
\\ ( , 2197kb)
Date: Mon, 9 Mar 2009 18:07:39 GMT (1280kb,D)

Title: Quantum interferometry with complex molecules
Authors: Markus Arndt, Klaus Hornberger
Categories: quant-ph
Comments: 29 pages, 11 figures; to appear in "Quantum Coherence in Solid State
   Systems", Proceedings of the International School of Physics "Enrico Fermi",
   Course CLXXI
   This chapter reviews recent experiments on matter wave interferometry with
large molecules. Starting from an elementary introduction to matter wave
physics we discuss far-field diffraction and near-field interferometry with
thermally excited many-body systems. We describe the constraints imposed by
decoherence and dephasing effects, and present an outlook to the future
challenges in macromolecule and cluster interferometry.
\\ ( , 1280kb)
Date: Mon, 9 Mar 2009 06:58:39 GMT (16kb)

Title: Manipulating Higher Partial-Wave Atom-Atom Interaction by Strong
   Photoassoiative Coupling
Authors: B. Deb and J. Harza
Categories: physics.atom-ph physics.optics
Comments: 4 pages 1 figure
   We show that it is possible to change not only s-wave but also higher partial
wave atom-atom interactions in cold collision in the presence of relatively
intense laser fields tuned near a photoassociative transition.
\\ ( , 16kb)
Date: Mon, 9 Mar 2009 17:47:45 GMT (1024kb,D)

Title: Simulating Hard Rigid Bodies
Authors: Cristiano De Michele
Categories: physics.comp-ph
Comments: 36 pages, 17 figures
   Several physical systems in condensed matter have been modeled approximating
their constituent particles as hard objects. In fact, the hard spheres model
has been one of the cornerstones of the computational and theoretical
description in condensed matter. The next level of description is to consider
particles as rigid objects of generic shape enriching enormously the possible
phenomenology. This kind of modeling will be interesting in all the situations
in which steric effect plays a relevant role. These include biology, soft
matter, granular material and molecular systems. Nevertheless, except for the
case of hard spheres systems, there are no general recipes for event-driven
Molecular Dynamics simulations of hard rigid bodies. Two similar algorithms for
calculating the distance between two convex hard rigid bodies and the contact
time of two colliding hard rigid bodies solving non-linear set of equations
will be described. Building on these two methods, an event-driven molecular
dynamics algorithm for simulating systems of convex hard rigid bodies will be
developed and illustrated in details. In order to optimize the collision
detection between very elongated hard rigid bodies, a novel nearest-neighbor
list method based on oriented bounding box will be introduced and fully
explained. Efficiency and performances of the new algorithm proposed will be
extensively tested in the special case of uniaxial hard ellipsoids and
applications in various scientific fields will be reported and discussed.
\\ ( , 1024kb)
Date: Tue, 10 Mar 2009 17:57:02 GMT (487kb)

Title: Superfluid as a powerful light source
Authors: Jinwu Ye, T. Shi, Longhua Jiang and C. P. Sun
Categories: cond-mat.mes-hall cond-mat.mtrl-sci
Comments: 4+ \epsilon pages, 2 color figures, REVTEX4
   Superfluid has been realized in Helium-4, Helium-3 and ultra-cold atoms. It
has been widely used in making high-precision devices and also in cooling
various systems. There have been extensive experimental search for possible
exciton superfluid in semiconductor electron-hole bilayer systems below liquid
Helium temperature. However, exciton superfluid are meta-stable and will
eventually decay through emitting photons. Here we show that the light emitted
from the excitonic superfluid has unique and unusual features not shared by any
other atomic or condensed matter systems. These remarkable features can be used
for high precision measurements, quantum information processing and also for
the development of a new generation of powerful opto-electronic devices.
\\ ( , 487kb)
Date: Mon, 9 Mar 2009 20:54:26 GMT (21kb)

Title: Stability of low-dimensional multicomponent Bose gases
Authors: Alexei Kolezhuk
Categories: cond-mat.other cond-mat.str-el
Comments: 4 pages, 2 figures
   It is shown that in case of low-dimensional geometries the interactions in
dilute Bose mixtures are strongly renormalized. This leads to a considerable
change of the stability conditions as compared to the mean-field results valid
in the high-density regime. Novel states with only partial phase separation or
collapse are predicted to appear in a certain window of inter-species
interaction and density.
\\ ( , 21kb)
Date: Mon, 9 Mar 2009 23:36:03 GMT (15kb)

Title: Mapping Approach for Quantum-Classical Time Correlation Functions
Authors: Ali Nassimi and Raymond Kapral
Categories: cond-mat.other quant-ph
   The calculation of quantum canonical time correlation functions is considered
in this paper. Transport properties, such as diffusion and reaction rate
coefficients, can be determined from time integrals of these correlation
functions. Approximate, quantum-classical expressions for correlation
functions, which are amenable to simulation, are derived. These expressions
incorporate the full quantum equilibrium structure of the system but
approximate the dynamics by quantum-classical evolution where a quantum
subsystem is coupled to a classical environment. The main feature of the
formulation is the use of a mapping basis where the subsystem quantum states
are represented by fictitious harmonic oscillator states. This leads to a full
phase space representation of the dynamics that can be simulated without appeal
to surface-hopping methods. The results in this paper form the basis for new
simulation algorithms for the computation of quantum transport properties of
large many-body systems.
\\ ( , 15kb)
Date: Tue, 10 Mar 2009 19:19:41 GMT (212kb)

Title: Inelastic Collisions of a Fermi Gas in the BEC-BCS Crossover
Authors: X. Du, Y. Zhang, and J. E. Thomas
Categories: cond-mat.other
Comments: 5 pages 4 figures
   We report the measurement of inelastic three-body and two-body collisional
decay rates for a two-component Fermi gas of $^6$Li, which are highly
suppressed by the Pauli exclusion principle. Our measurements are made in the
BEC-BCS crossover regime, near the two-body collisional (Feshbach) resonance.
At high temperature (energy) the data shows a dominant three-body decay
process, which is studied as a function of bias magnetic field. At low energy,
the data shows a coexistence of two-body and three-body decay processes near
and below the Feshbach resonance. Below resonance, the observed two-body
inelastic decay can arise from molecule-atom and molecule-molecule collisions.
We suggest that at and above resonance, an effective two-body decay rate arises
from collisions between atoms and correlated (Cooper) pairs that can exist at
sufficiently low temperature.
\\ ( , 212kb)
Date: Tue, 10 Mar 2009 11:27:49 GMT (523kb)

Title: Stationary light in cold atomic gases
Authors: Gor Nikoghosyan and Michael Fleischhauer
Categories: quant-ph
Comments: 6 pages, 5 figures
   We discuss stationary light created by a pair of counter-propagating control
fields in Lambda-type atomic gases with electromagnetically induced
transparency for the case of negligible Doppler broadening. In this case the
secular approximation used in the discussion of stationary light in hot vapors
is no longer valid. We discuss the quality of the effective light-trapping
system and show that in contrast to previous claims it is finite even for
vanishing ground-state dephasing. The dynamics of the photon loss is in general
non exponential and can be faster or slower than in hot gases.
\\ ( , 523kb)
arXiv:0807.5062 (*cross-listing*)
Date: Thu, 31 Jul 2008 13:46:29 GMT (51kb)
Date (revised v2): Wed, 15 Oct 2008 21:03:06 GMT (51kb)
Date (revised v3): Tue, 10 Mar 2009 06:21:12 GMT (51kb)

Title: Atom-atom correlations in colliding Bose-Einstein condensates
Authors: Magnus Ogren and K. V. Kheruntsyan
Categories: cond-mat.other cond-mat.stat-mech quant-ph
Comments: Minor corrections to the text; final published version
Journal-ref: Phys. Rev. A 79, 021606(R) (2009)
   We analyze atom-atom correlations in the s-wave scattering halo of two
colliding condensates. By developing a simple perturbative approach, we obtain
explicit analytic results for the collinear (CL) and back-to-back (BB)
correlations corresponding to realistic density profiles of the colliding
condensates with interactions. The results in the short time limit are in
agreement with the first-principles simulations using the positive-$P$
representation and provide analytic insights into the experimental observations
of Perrin et al. [Phys. Rev. Lett. 99, 150405 (2007)]. For long collision
durations, we predict that the BB correlation becomes broader than the CL
\\ ( , 51kb)
Date: Mon, 9 Mar 2009 22:40:55 GMT (13kb)

Title: Calculation of Stark-induced absorption on the 6s6p ^3P_1 - 6s^2 ^1S_0
   transition in Hg
Authors: K. Beloy, V. A. Dzuba, A. Derevianko
Categories: physics.atom-ph
Comments: 5 pages
   We carry out relativistic many-body calculations of the Stark-induced
absorption coefficient on the 254-nm $6s6p ^3P_1 (F=1/2) - 6s^2 ^1S_0$ line of
$^{199}$Hg atom, the effect considered before by Lamoreaux and Fortson using a
simple central field estimate [Phys. Rev. A {\bf 46}, 7053 (1992)]. The
Stark-induced admixing of states of opposite parity opens additional M1 and E2
transition channels. We find that the resulting M1-E1 absorption dominates over
E2-E1 absorption. The value of the E2-E1 absorption coefficient depends
strongly on the details of treatment of the correlation problem. As a result,
our numerical values differ substantially from those of the earlier central
field calculation. Reliable calculation of this effect can enable a useful
experimental check on the optical technique being used to search for a
permanent electric dipole moment of the $^{199}$Hg atom.
\\ ( , 13kb)
Date: Wed, 11 Mar 2009 03:06:00 GMT (344kb)

Title: Heat capacity peak in solid 4He: Effects of disorder and 3He impurities
Authors: X. Lin, A. C. Clark, Z. G. Cheng and M. H. W. Chan
Categories: cond-mat.other
Comments: 14 pages, 3 figures
   Heat capacity measurements with significantly improved resolution find the
presence of a peak in a solid 4He sample in coexistence with liquid. With
improved crystallinity, the peak decreases in height and moves to lower
temperature. A hysteretic heat capacity signature consistent with 3He-4He phase
separation, not detected in an earlier work is clearly observed.
\\ ( , 344kb)
Date: Wed, 11 Mar 2009 03:59:54 GMT (138kb)

Title: Spin-structures of N-boson systems with nonzero spins - an analytically
   solvable model with pairing force
Authors: Chengguang Bao
Categories: cond-mat.other
Comments: 10 pages, 2 figures, accepted by Few-Body Systems
   A model is proposed to study the possible pairing structures of N-boson
systems with nonzero spin. Analytical solutions have been obtained. The
emphasis is placed on the spin-structures of ground states with attractive or
repulsive pairing force, and with or without the action of a magnetic field. A
quantity (an analogue of the two-body density function) is defined to study the
spin-correlation between two bosons in N-body systems. The excitation of the
system has also been studied.
\\ ( , 138kb)
Date: Wed, 11 Mar 2009 06:16:01 GMT (141kb)

Title: Heat Transport in Magnon Bose-Einstein-Condensation State of a
   Low-Dimensional Quantum Magnet
Authors: X. F. Sun, W. Tao, X. M. Wang, C. Fan
Categories: cond-mat.str-el
Comments: 5 pages, 4 figures
   We report a study of the low-temperature thermal conductivity of
NiCl_{2}-4SC(NH_{2})_{2}, which is a spin-1 chain system exhibiting the magnon
Bose-Einstein condensation (BEC) in magnetic field. It is found that the low-T
thermal conductivity along the spin-chain direction shows strong anomalies at
the lower and upper critical fields of the magnon BEC state. In this state,
magnons act mainly as phonon scatterers at relatively high temperature, but
change their role to heat carriers upon temperature approaching zero. The
result demonstrates a large thermal conductivity in the magnon BEC state and
points to a direct analog between the magnon BEC and the conventional one.
\\ ( , 141kb)
Date: Wed, 11 Mar 2009 09:04:33 GMT (521kb)

Title: The effect of population imbalance on the
   Berezinskii-Kosterlitz-Thouless phase transition in a superfluid Fermi gas
Authors: J. Tempere, S.N. Klimin, J.T. Devreese
Categories: cond-mat.stat-mech cond-mat.other
Comments: 3 figures
   The Berezinskii-Kosterlitz-Thouless (BKT) mechanism describes the breakdown
of superfluidity in a two-dimensional Bose gas or a two-dimensional gas of
paired fermions. In the latter case, a population imbalance between the two
pairing partners in the Fermi mixture is known to influence pairing
characteristics. Here, we investigate the effects of imbalance on the
two-dimensional BKT superfluid transition, and show that superfluidity is even
more sensitive to imbalance than for three dimensional systems.
Finite-temperature phase diagrams are derived using the functional integral
formalism in combination with a hydrodynamic action functional for the phase
fluctuations. This allow to identify a phase separation region and tricritical
points due to imbalance. In contrast to superfluidity in the three-dimensional
case, the effect of imbalance is also pronounced in the strong-coupling regime.
\\ ( , 521kb)
Date: Wed, 11 Mar 2009 11:58:52 GMT (227kb)

Title: Dynamics of formation and decay of coherence in a polariton condensate
Authors: E. del Valle, D. Sanvitto, A. Amo, F.P. Laussy, A. Andre, C. Tejedor
   and L. Vina
Categories: cond-mat.mes-hall
   We study the dynamics of formation and decay of a condensate of microcavity
polaritons. We investigate the relationship between the number of particles,
the emission's linewidth and its degree of linear polarization which serves as
the order parameter. Tracking the condensate's formation, we show that, even
when interactions are negligible, coherence is not determined only by
occupation of the ground state. As a result of the competition between the
coherent and thermal fractions of the condensate, the highest coherence is
obtained some time after the particle number has reached its maximum.
\\ ( , 227kb)
Date: Wed, 11 Mar 2009 17:32:54 GMT (232kb)

Title: Quantum distillation: dynamical generation of low-entropy states of
   strongly correlated fermions in an optical lattice
Authors: F. Heidrich-Meisner, S. R. Manmana, M. Rigol, A. Muramatsu, A. E.
   Feiguin, E. Dagotto
Categories: cond-mat.str-el
Comments: 4 pages Revtex 4, 4 eps figures
   Correlations between particles can lead to subtle and sometimes
counterintuitive phenomena. We analyze one such case, occurring during the
sudden expansion of fermions in a lattice when the initial state has a strong
admixture of double occupancies. We promote the notion of quantum distillation:
during the expansion, and in the presence of strongly repulsive interactions,
tightly bound pairs group together, forming a nearly ideal band insulator,
which is metastable with a low entropy. We discuss how this effect could be
used for cooling purposes in experiments with two-component Fermi gases.
\\ ( , 232kb)
Date: Wed, 11 Mar 2009 16:04:47 GMT (328kb,D)

Title: Quantum breathing mode of trapped bosons and fermions at arbitrary
Authors: S. Bauch, K. Balzer, C. Henning, and M. Bonitz
Categories: quant-ph
   An analysis of the quantum breathing behavior of few-particle Coulomb systems
in one- and two-dimensional harmonic traps is presented. We report the
existence of \emph{two independent breathing modes} and present exact numerical
results for two particles at any coupling strength which smoothly connect the
two known limits of an \emph {ideal} quantum and a strongly coupled \emph
{classical} system. Substantial differences in the breathing frequency of
two-dimensional fermions and bosons are observed which may be used as a
sensitive experimental tool to probe confined interacting quantum systems.
\\ ( , 328kb)
Date: Thu, 12 Mar 2009 08:49:39 GMT (159kb)

Title: Critical Velocity in a Bose Gas in a Moving Optical Lattice at Finite
Authors: Emiko Arahata, Tetsuro Nikuni
Categories: cond-mat.other
Comments: 9 pages, 5 figures
   We study the critical velocity of a Bose-condensed gas in a moving
one-dimensional (1D) optical lattice potential at finite temperatures. Solving
the Gross-Pitaeavskii equation and the Bogoliubov equations, within the Popov
approximation, we calculate the Bogoliubov excitations with varying lattice
velocity. From the condition of the negative excitation energy, we determine
the critical velocity as a function of the lattice depth and the temperature.
We find that the critical velocity decreases rapidly with increasing the
temperature; this result is consistent with the experimental observations.
Moreover, the critical velocity shows a rapid decrease with increasing lattice
depth. This tendency is much more significant than in the previous works
ignoring the effect of thermal excitations in the radial direction.
\\ ( , 159kb)
Date: Thu, 12 Mar 2009 19:39:51 GMT (498kb,D)

Title: Emergent superfluid crystals, frustration, and topologically defected
   states in multimode cavity QED
Authors: Sarang Gopalakrishnan, Benjamin L. Lev, and Paul M. Goldbart
Categories: cond-mat.other
Comments: 8 pages, 3 figures
   We propose that condensed matter phenomena involving the spontaneous
emergence and dynamics of crystal lattices can be realized in the setting of
ultracold Bose-condensed atoms coupled to multimode cavities. Previously, it
was shown that in the case of a transversely pumped single-mode cavity, the
atoms self-organize at either the even or the odd antinodes of the cavity mode,
given sufficient pump intensity, and hence spontaneously break a discrete
translational symmetry. Here, we demonstrate that in multimode cavities the
self-organization brings the additional feature of continuous translational
symmetry breaking, via a variant of Brazovskii's transition, thus paving the
way for realizations of compliant lattices and associated phenomena, e.g.,
quantum melting, topological defects, frustration, glassiness, and even
supersolidity; such phenomena are absent in ultracold atomic systems when the
optical lattices are externally imposed. We apply a functional integral
approach to this many-body cavity QED system, which enables us, inter alia, to
calculate transition thresholds, explore fluctuations near this transition, and
determine how such fluctuations are manifest in the light emitted from the
\\ ( , 498kb)
Date: Wed, 11 Mar 2009 20:03:16 GMT (214kb,D)

Title: Magnetometry via a double-pass continuous quantum measurement of atomic
Authors: Bradley A. Chase, Ben Q. Baragiola, Heather L. Partner, Brigette D.
   Black, JM Geremia
Categories: quant-ph
Comments: 17 pages
   We argue that it is possible in principle to reduce the uncertainty of an
atomic magnetometer by double-passing a far-detuned laser field through the
atomic sample as it undergoes Larmor precession. Numerical simulations of the
quantum Fisher information suggest that, despite the lack of explicit
multi-body coupling terms in the system's magnetic Hamiltonian, the parameter
estimation uncertainty in such a physical setup scales better than the
conventional Heisenberg uncertainty limit over a specified but arbitrary range
of particle number N. Using the methods of quantum stochastic calculus and
filtering theory, we demonstrate numerically an explicit parameter estimator
(called a quantum particle filter) whose observed scaling follows that of our
calculated quantum Fisher information. Moreover, the quantum particle filter
quantitatively surpasses the uncertainty limit calculated from the quantum
Cramer-Rao inequality based on a magnetic coupling Hamiltonian with only
single-body operators. We also show that a quantum Kalman filter is
insufficient to obtain super-Heisenberg scaling, and present evidence that such
scaling necessitates going beyond the manifold of Gaussian atomic states.
\\ ( , 214kb)

The replacements:

replaced with revised version Thu, 5 Mar 2009 07:12:43 GMT (28kb)

Title: Comment on "Laser cooling of rubidium atoms from background vapor in
   diffuse light"
Authors: V.A. Kuz'menko
Categories: physics.gen-ph
Comments: 2 pages, 1 figure
\\ ( , 28kb)
replaced with revised version Thu, 5 Mar 2009 14:01:24 GMT (24kb)

Title: Efficient atomization of cesium metal in solid helium by low energy (10
   $\mu$J) femtosecond pulses
Authors: Mathieu Melich (LKB - Lhomond), Jacques Dupont-Roc (LKB - Lhomond),
   Philippe Jacquier (LKB - Lhomond)
Categories: physics.atm-clus cond-mat.other physics.atom-ph quant-ph
\\ ( , 24kb)
replaced with revised version Mon, 9 Mar 2009 10:10:34 GMT (1106kb)

Title: Multiband bosons in optical lattices
Authors: J. Larson, A. Collin, and J.-P. Martikainen
Categories: cond-mat.other quant-ph
Report-no: NORDITA-2008-50
Journal-ref: Phys. Rev. A 79, 033603 (2009)
\\ ( , 1106kb)
replaced with revised version Tue, 10 Mar 2009 05:54:25 GMT (9kb)

Title: A condition for the Bose-Einstein transition in the superfluid liquid
Authors: V. N. Minasyan
Categories: cond-mat.supr-con
Comments: 8 pages
\\ ( , 9kb)
replaced with revised version Tue, 10 Mar 2009 01:09:20 GMT (501kb)

Title: Dynamics of rotating two-component Bose-Einstein Condensates
Authors: I. Corro, R.G. Scott, and A.M. Martin
Categories: cond-mat.other quant-ph
Comments: v4: more material added. 9 pages, 6 figures v5: figures fixed
\\ ( , 501kb)
replaced with revised version Tue, 10 Mar 2009 10:19:08 GMT (244kb)

Title: Ground state of low dimensional dipolar gases: linear and zigzag chains
Authors: G. E. Astrakharchik, Giovanna Morigi, Gabriele De Chiara, and J.
Categories: cond-mat.other quant-ph
Journal-ref: Phys. Rev. A 78, 063622 (2008); Virtual Journal of Nanoscale
   Science & Technology, vol. 19, Issue 2 (2009)
\\ ( , 244kb)
replaced with revised version Tue, 10 Mar 2009 06:21:12 GMT (51kb)

Title: Atom-atom correlations in colliding Bose-Einstein condensates
Authors: Magnus Ogren and K. V. Kheruntsyan
Categories: cond-mat.other cond-mat.stat-mech quant-ph
Comments: Minor corrections to the text; final published version
Journal-ref: Phys. Rev. A 79, 021606(R) (2009)
\\ ( , 51kb)
replaced with revised version Tue, 10 Mar 2009 04:19:49 GMT (26kb)

Title: Detection of valence bond order of ultracold atoms in optical lattices
   by off-resonant scattering of cavity photons
Authors: Jinwu Ye, Jiangming Zhang, Wuming Liu, Keye Zhang, Yan Li and Weiping
Categories: physics.atom-ph cond-mat.str-el physics.optics
Comments: 4+ \epsilon pages, 3 color figures, REVTEX
\\ ( , 26kb)
replaced with revised version Wed, 11 Mar 2009 08:02:00 GMT (75kb)

Title: Semilinear response for the heating rate of cold atoms in vibrating
Authors: Alexander Stotland, Doron Cohen, Nir Davidson
Categories: quant-ph cond-mat.mes-hall
Comments: 6 pages, 6 figures, improved version to be published in Europhysics
\\ ( , 75kb)
replaced with revised version Wed, 11 Mar 2009 08:45:34 GMT (117kb)

Title: Exploring dynamic localization with a Bose-Einstein condensate
Authors: Andre Eckardt, Martin Holthaus, Hans Lignier, Alessandro Zenesini,
   Donatella Ciampini, Oliver Morsch, and Ennio Arimondo
Categories: cond-mat.other
Comments: 7 pages, 4 figures
Journal-ref: Phys. Rev. A 79, 013611 (2009)
DOI: 10.1103/PhysRevA.79.013611
\\ ( , 117kb)
replaced with revised version Tue, 10 Mar 2009 21:54:41 GMT (115kb)

Title: A geometrical approach to the dynamics of spinor condensates I:
Authors: Ryan Barnett, Daniel Podolsky, Gil Refael
Categories: cond-mat.other cond-mat.str-el
Comments: 12 pages. First paper in two-part series
\\ ( , 115kb)
replaced with revised version Wed, 11 Mar 2009 00:53:54 GMT (52kb)

Title: Adiabatic approximation with exponential accuracy for many-body systems
   and quantum computation
Authors: D.A. Lidar, A.T. Rezakhani, A. Hamma
Categories: quant-ph math-ph math.MP
Comments: 22 pages, 2 figures. Supersedes arXiv:0804.0604. v2: some
   corrections, new remarks, and a new subsection on the adiabatic theorem for
   open systems. v3: additional corrections
\\ ( , 52kb)
replaced with revised version Thu, 12 Mar 2009 03:21:15 GMT (513kb)

Title: Theory for superfluidity in a Bose system
Authors: Zhidong Hao
Categories: cond-mat.supr-con
Comments: 17 pages 12 figures; revised; and added quatitative description of
   Hess-Fiarbank effect
\\ ( , 513kb)
arXiv:0810.2089 (*cross-listing*)
replaced with revised version Thu, 12 Mar 2009 10:07:20 GMT (37kb)

Title: Can stochastic quantization evade the sign problem? -- the relativistic
   Bose gas at finite chemical potential
Authors: Gert Aarts (Swansea University)
Categories: hep-lat cond-mat.other hep-ph nucl-th
Comments: 4 pages, 4 eps figures, v2: minor changes, outlook expanded,
   references added, to appear in PRL
\\ ( , 37kb)
replaced with revised version Thu, 12 Mar 2009 09:24:55 GMT (28kb)

Title: Magnetic and Superfluid Transitions in the d=1 Spin-1 Boson Hubbard
Authors: G.G. Batrouni, V.G. Rousseau, and R.T. Scalettar
Categories: cond-mat.other
Comments: Added results
\\ ( , 28kb)
replaced with revised version Thu, 12 Mar 2009 11:46:33 GMT (88kb)

Title: Bloch oscillations in one-dimensional spinor gas
Authors: D.M. Gangardt, A. Kamenev
Categories: cond-mat.stat-mech
Comments: 4 pages, 2 figures
Journal-ref: Phys. Rev. Lett. 102, 070402 (2009)
DOI: 10.1103/PhysRevLett.102.070402
\\ ( , 88kb)
replaced with revised version Thu, 12 Mar 2009 08:02:01 GMT (580kb,D)

Title: A simple integrated single-atom detector
Authors: Marco Wilzbach, Dennis Heine, S\"onke Groth, Xiyuan Liu, Thomas Raub,
   Bj\"orn Hessmo, J\"org Schmiedmayer
Categories: physics.atom-ph physics.optics
Comments: 3 pages, 3 figures
Journal-ref: Optics Letters, Vol. 34, page 259 (2009)
DOI: 10.1364/OL.34.000259
\\ ( , 580kb)

Till next time,

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,        
Matt's arXiv selection: weekly summary of cold-atom papers from
Legal stuff: Unless stated otherwise, this e-mail represents only the
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Received on Thu May 21 2009 - 15:50:53 EST

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