Matt's arXiv sele tion: week ending 11 April 2008.

From: Matthew Davis <>
Date: Thu, 24 Apr 2008 22:11:06 +1000

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

Just when you were wondering what had happened to your weekly arXiv email, it's
back! I took a weeks holiday last week and the lead up to being away and the
subsequent catching up has lead to the delay.

This week there are 27 new preprints and 18 replacements.

Date: Thu, 3 Apr 2008 21:20:17 GMT (48kb)

Title: Topological order from quantum loops and nets
Authors: Paul Fendley
Categories: cond-mat.stat-mech cond-mat.str-el
   I define models of quantum loops and nets which have ground states with
topological order. These make possible excited states comprised of deconfined
anyons with non-abelian braiding. With the appropriate inner product, these
quantum loop models are equivalent to net models whose topological weight
involves the chromatic polynomial. A useful consequence is that the models have
a quantum self-duality, making it possible to find a simple Hamiltonian
preserving the topological order. For the square lattice, this Hamiltonian has
only four-spin interactions.
\\ ( , 48kb)
Date: Fri, 4 Apr 2008 16:42:06 GMT (82kb)

Title: Collective modes in asymmetric ultracold Fermi systems
Authors: Elena Gubankova, Massimo Mannarelli and Rishi Sharma
Categories: cond-mat.supr-con cond-mat.stat-mech
Comments: 22 pages, 7 figures
   We derive the low energy effective action for the collective modes in systems
of fermions interacting via a short-range s-wave attraction, featuring unequal
chemical potentials for the two fermionic species (asymmetric systems). As a
consequence of the attractive interaction, fermions form a condensate that
spontaneously breaks the U(1) symmetry associated with total number
conservation. Therefore at sufficiently small temperatures and asymmetries, the
system is a superfluid. We obtain criteria of stability for the system from the
coefficients of the low energy effective Lagrangian of the modes describing
fluctuations in the magnitude (Higgs mode) and in the phase (Goldstone mode) of
the difermion condensate. We find that there is a region in parameter space
where the system features one gapless Fermi surface, and is stable. Regions
with two gapless Fermi surfaces are excluded. In the stable gapless region, for
certain values of parameters, the Higgs mode is light. Its mass decreases with
increasing mismatch between the chemical potentials of the two populations, if
we keep the scattering length and the gap parameter constant. Furthermore, we
find that the elasticity of the Higgs mode diverges at the boundary of the
gapless region and these two features may lead to experimentally detectable
effects. As an example, we argue that if the superfluid is put in rotation, the
square of the radius of the outer core is proportional to the ratio of the
Higgs elasticity and the Higgs mass. Therefore one should detect an increase in
the radius of the vortex on increasing the asymmetry, when we pass through the
relevant region in the gapless superfluid phase. Finally, by gauging the global
U(1) symmetry, we relate the coefficients of the effective Lagrangian of the
Goldstone mode with the screening masses of the gauge field.
\\ ( , 82kb)
Date: Tue, 1 Apr 2008 21:45:43 GMT (733kb)

Title: Quantum State Engineering and Precision Metrology using
   State-Insensitive Light Traps
Authors: Jun Ye, H. J. Kimble, and Hidetoshi Katori
Categories: quant-ph physics.atom-ph
Comments: 23 pages of main text, 4 figures, and 12 pages of Supporting Online
   Material (SOM)
   Precision metrology and quantum measurement often demand matter be prepared
in well defined quantum states for both internal and external degrees of
freedom. Laser-cooled neutral atoms localized in a deeply confining optical
potential satisfy this requirement. With an appropriate choice of wavelength
and polarization for the optical trap, two electronic states of an atom can
experience the same trapping potential, permitting coherent control of
electronic transitions independent of the atomic center-of-mass motion. We
review a number of recent experiments that use this approach to investigate
precision quantum metrology for optical atomic clocks and coherent control of
optical interactions of single atoms and photons within the context of cavity
quantum electrodynamics. We also provide a brief survey of promising prospects
for future work.
\\ ( , 733kb)
Date: Mon, 7 Apr 2008 13:25:27 GMT (33kb)

Title: Particle partitioning entanglement in itinerant many-particle systems
Authors: O.S. Zozulya, Masudul Haque, K. Schoutens
Categories: cond-mat.other cond-mat.str-el
Comments: 4 pages, 4 figures
   For itinerant fermionic and bosonic systems, we study `particle
entanglement', defined as the entanglement between two subsets of particles
making up the system. We formulate the general structure of particle
entanglement in many-fermion ground states, analogous to the `area law' for the
more usually studied entanglement between spatial regions. Basic properties of
particle entanglement are uncovered by considering relatively simple itinerant
\\ ( , 33kb)
Date: Mon, 7 Apr 2008 06:43:00 GMT (46kb)

Title: Fast rotating condensates in an asymmetric harmonic trap
Authors: Amandine Aftalion (LJLL), Xavier Blanc (LJLL), Nicolas Lerner (IMJ)
Categories: cond-mat.other
Comments: 4 pages, 2 figures
Proxy: ccsd hal-00270540
   We investigate the effect of the anisotropy of a harmonic trap on the
behaviour of a fast rotating Bose-Einstein condensate. Fast rotation is reached
when the rotational velocity is close to the smallest trapping frequency,
thereby deconfining the condensate in the corresponding direction. A striking
new feature is the non-existence of visible vortices for the ground state. The
condensate can be described with the lowest Landau level set of states, but
using distorted complex coordinates. We find that the coarse grained atomic
density behaves like an inverted parabola with large radius in the deconfined
direction, and like a fixed Gaussian in the other direction. It has no visible
vortices, but invisible vortices which are needed to recover the mixed
Thomas-Fermi Gaussian profile. There is a regime of small anisotropy and
intermediate rotational velocity where the behaviour is similar to the
isotropic case: a hexagonal Abrikosov lattice of vortices, with an inverted
parabola profile.
\\ ( , 46kb)
Date: Mon, 7 Apr 2008 14:17:16 GMT (30kb)

Title: Vortex core states in superfluid Fermi-Fermi mixtures with unequal
Authors: M. Iskin
Categories: cond-mat.supr-con cond-mat.other
Comments: 4+ pages with 3 figures, to be submitted to PRA
   We analyze the vortex core states of two-species (mass imbalanced) superfluid
fermion mixtures as a function of the two-body binding energy in two
dimensions. In particular, we solve the self-consistent Bogoliubov-de Gennes
equations for a population balanced but mass imbalanced mixture of $^{6}$Li and
$^{40}$K atoms at zero temperature. We find that the vortex core is mostly
filled with the light-mass ($^{6}$Li) fermions and that the core density of
heavy-mass ($^{40}$K) fermions is highly depleted. This is in contrast with the
one-species (mass balanced) mixtures, where equal amount of density depletion
is found at the vortex core for both pseudo-spin components.
\\ ( , 30kb)
Date: Sun, 6 Apr 2008 12:49:37 GMT (285kb)

Title: Controlling transition probability from matter-wave soliton to chaos
Authors: Qianquan Zhu, Wenhua Hai, Shiguang Rong
Categories: quant-ph
Comments: 4 pages, 2 figures
   For a Bose-Einstein condensate loaded into a weak traveling optical
superlattice it is demonstrated that under a stochastic initial set and in a
given parameter region the solitonic chaos appears with a certain probability.
Effects of the lattice depths and wave vectors on the chaos probability are
investigated analytically and numerically, and different chaotic regions
associated with different chaos probabilities are found. The results suggest a
feasible method for eliminating or strengthening chaos by modulating the moving
superlattice experimentally.
\\ ( , 285kb)
Date: Sat, 5 Apr 2008 23:19:38 GMT (8kb)

Title: Mathematical Models in Physics : a Quest for Clarity
Authors: Elemer E. Rosinger
Categories: physics.gen-ph
   The role of mathematical models in physics has for longer been well
established. The issue of their proper building and use appears to be less
clear. Examples in this regard from relativity and quantum mechanics are
mentioned. Comments concerning a more appropriate way in setting up and using
mathematical models in physics are presented.
\\ ( , 8kb)
Date: Mon, 7 Apr 2008 20:52:44 GMT (787kb)

Title: Signatures of Strong Correlations in One-Dimensional Ultra-Cold Atomic
   Fermi Gases
Authors: Paata Kakashvili, S. G. Bhongale, Han Pu and C. J. Bolech
Categories: cond-mat.other cond-mat.str-el
Comments: 4 pages, 2 figures
   Recent success in manipulating ultra-cold atomic systems allows to probe
different strongly correlated regimes in one-dimension. Regimes such as the
(spin-coherent) Luttinger liquid and the spin-incoherent Luttinger liquid can
be realized by tuning the inter-atomic interaction strength and trap
parameters. We identify the noise correlations of density fluctuations as a
robust observable (uniquely suitable in the context of trapped atomic gases) to
discriminate between these two regimes. Finally, we address the prospects to
realize and probe these phenomena experimentally using optical lattices.
\\ ( , 787kb)
Date: Tue, 8 Apr 2008 09:15:16 GMT (4kb)

Title: The model charged spinless nonideal Bose gas within finite temperatures
Authors: V. N. Minasyan
Categories: cond-mat.supr-con
Comments: 8 pages
   First, it is demonstrated an exactly solution of the model of charged
nonideal Bose gas, at quantity of the condensate fraction
$0\leq\frac{N_0}{N}\leq 1$. As new result of presented theory is that an
application of the S-wave scattering between charged bosons, in addition to a
repulsive Coulomb interaction, leads to a creation of phonon term in the energy
spectrum of plasmon excitations. As new result of presented theory, there are
absent the phonons and plasmon gap, at critical temperature $T_c$.
\\ ( , 4kb)
Date: Tue, 8 Apr 2008 13:57:00 GMT (8kb)

Title: Hydrodynamics of Bose and Fermi superfluids at zero temperature: the
   superfluid nonlinear Schodinger equation
Authors: Luca Salasnich (CNR-INFM and CNISM, University of Padua)
Categories: cond-mat.stat-mech cond-mat.other
Comments: 4 pages, no figures, prepared for the Special Issue of Laser Physics:
   Physics of Cold Trapped Atoms
   We discuss the zero-temperature hydrodynamics equations of bosonic and
fermionic superfluids and their connection with generalized Gross-Pitaevskii
and Ginzburg-Landau equations through a single superfluid nonlinear Schrodinger
\\ ( , 8kb)
Date: Tue, 8 Apr 2008 07:50:47 GMT (90kb)

Title: Quantum improvement of time transfer between remote clocks
Authors: Brahim Lamine (LKB - Jussieu), Claude Fabre (LKB - Jussieu), Nicolas
   Treps (LKB - Jussieu)
Categories: quant-ph
Proxy: ccsd hal-00270912
   Exchanging light pulses to perform accurate space-time positioning is a
paradigmatic issue of physics. It is ultimately limited by the quantum nature
of light, which introduces fluctuations in the optical measurements and leads
to the so-called Standard Quantum Limit (SQL). We propose a new scheme
combining homodyne detection and mode-locked femtosecond lasers that lead to a
new SQL in time transfer, potentially reaching the yoctosecond range
(10^-21-10^-24 s). We prove that no other measurement strategy can lead to
better sensitivity with shot noise limited light. We then demonstrate that this
already very low SQL can be overcome using appropriately multimode squeezed
light. Benefitting from the large number of photons used in the experiment and
from the optimal choice of both the detection strategy and of the quantum
resource, the proposed scheme represents a significant potential improvement in
space-time positioning.
\\ ( , 90kb)
Date: Tue, 8 Apr 2008 00:22:14 GMT (248kb)

Title: Gaussian Schell Source as Model for Slit-Collimated Atomic and Molecular
Authors: Ben McMorran, Alex Cronin
Categories: physics.optics physics.atom-ph
   We show how to make a Gaussian Schell-model (GSM) beam. Then we compare the
intensity profile, the transverse coherence width and the divergence angle of a
GSM beam with those same properties of a beam that is collimated with two
hard-edged slits. This work offers an intuitive way to understand various
interferometer designs, and we compare our results with data.
\\ ( , 248kb)
Date: Tue, 8 Apr 2008 22:09:15 GMT (17kb)

Title: Construction of density operator for a general mean-field Hamiltonian
   and its application to the models of correlated fermions
Authors: Jakub J\c{e}drak, Jozef Spa{\l}ek
Categories: cond-mat.str-el cond-mat.stat-mech
Comments: 17 pages
   We analyze a class of the mean-field lattice-fermion Hamiltonians. We
construct the corresponding grand-canonical density operator for such a model
system. New terms are introduced, and may be interpreted as local fugacities,
molecular fields, etc. The presence of such terms is an unavoidable consequence
of the consistent statistical description. Although in some cases (e.g. the
Hartree or the Hartree-Fock type of approximations) the presented formalism is
redundant, in general (e.g. for a renormalized t-J model) it leads to
nontrivial modifications. The case of zero temperature is also briefly
\\ ( , 17kb)
Date: Wed, 9 Apr 2008 16:57:38 GMT (119kb)

Title: Temperature and final state effects in radio frequency spectroscopy
   experiments on atomic Fermi gases
Authors: Yan He, Chih-Chun Chien, Qijin Chen, and K. Levin
Categories: cond-mat.supr-con cond-mat.str-el
Comments: 4 pages, 4 figures
   We present a formalism for addressing radio frequency (RF) spectroscopy
experiments in homogeneous atomic Fermi gases in the presence of pairing, but
not necessarily superfluidity, and at finite temperatures, $T$. Our approach
includes final state effects and our calculated spectra satisfy the zeroth- and
first-moment sum rules at all $T$. We show how the continuum and bound state
contributions depend significantly on $T$, and explain recent RF experiments on
"bound-bound" transitions. We make predictions for future experiments.
\\ ( , 119kb)
Date: Wed, 9 Apr 2008 11:21:48 GMT (424kb)

Title: Quantum Phase Transition Induced by a Preformed Pair in a Boson-Fermion
   Model of Fulleride Superconductivity
Authors: Richard H. Squire, Norman H. March
Categories: cond-mat.supr-con cond-mat.str-el
Comments: presented at Sanibel Symposium, Feb 2008
   There continues to be enormous interest in the BCS to BEC transition as there
still is no exact theory. We recently reported a revealing reinterpretation of
the condensed phase Boson-Fermion Model (BFM) by comparing it to a cold atom
formulation [1]. While the ground and singly excited states appear to remain
continuous in all models we have examined, the collective modes contain a
singularity due to a Feshbach resonance (tuned by doping) causing a breakdown
of the Migdal theorem. As a result of vertex corrections, there is a
fundamental change in the nature of the superconductivity due to the formation
of preformed pairs as the previously suggested location [1] of a quantum
critical point in the fulleride phase diagram is passed. The result is a
quantum phase transition (QPT) between BCS and BEC-like (or Feshbach resonance)
superconductivity (SC).
   We discuss features of the resonance and the role of the experimentally
observed preformed pair formation in fullerides, essential to the Boson-Fermion
Model (BFM), and often speculated since the work of Nozieres and Schmitt-Rink
[17]. Here, we present arguments to establish a model of the preformed pair
which can be favorably compared to a circular charge density wave (CDW)
isolated on a fulleride molecule. The binding is much larger than a Cooper
pair. The CDW seems to be stabalized by splitting of the Jahn-Teller active
vibrational modes to reduce Coulomb repulsions. Our conclusions are: 1) the
doping of two electrons into triply degenerate orbitals results in the
experimentally observed singlet state (CDW); and 2) this CDW (preformed pair)
has a dual role as doping is varied: suppression of BCS SC and enabling a
Feshbach resonance form of SC.
\\ ( , 424kb)
Date: Wed, 9 Apr 2008 13:23:58 GMT (62kb)

Title: Properties of Fractional Exclusion Statistics in Interacting Particle
Authors: Drago\c{s}-Victor Anghel
Categories: cond-mat.stat-mech cond-mat.other
Comments: 8 pages, 3 figures, to appear in Rom. J. Phys. Is a continuation of
   J. Phys. A: Math. Theor. 40 F1013-F1019 (2007); arXiv:0710.0724, and
   We show that fractional exclusion statistics is manifested in general in
interacting systems and we discuss the conjecture recently introduced (J. Phys.
A: Math. Theor. 40, F1013, 2007), according to which if in a thermodynamic
system the mutual exclusion statistics parameters are not zero, then they have
to be proportional to the dimension of the Hilbert space on which they act. By
using simple, intuitive arguments, but also concrete calculations in
interacting systems models, we show that this conjecture is not some abstract
consequence of unphysical modeling, but is a natural--and for a long time
overlooked--property of fractional exclusion statistics. We show also that the
fractional exclusion statistics is the consequence of interaction between the
particles of the system and it is due to the change from the description of the
system in terms of free-particle energies, to the description in terms of the
quasi-particle energies. From this result, the thermodynamic equivalence of
systems of the same, constant density of states, but any exclusion statistics
follows immediately.
\\ ( , 62kb)
Date: Wed, 9 Apr 2008 15:55:21 GMT (113kb,D)

Title: Time-dependent current-density-functional theory of spin-charge
   separation and spin drag in one-dimensional ultracold Fermi gases
Authors: Gao Xianlong, Marco Polini, Diego Rainis, M.P. Tosi, G. Vignale
Categories: cond-mat.str-el
Comments: 4+epsilon pages, 3 figures, submitted. High-quality figures can be
   requested to the authors
   Motivated by the large interest in the non-equilibrium dynamics of
low-dimensional quantum many-body systems, we present a fully-microscopic
theoretical and numerical study of the "charge" and "spin" dynamics in a
one-dimensional ultracold Fermi gas following a quench. Our approach, which is
based on time-dependent current-density-functional theory, is applicable well
beyond the linear-response regime and produces both spin-charge separation and
spin-drag-induced broadening of the spin packets.
\\ ( , 113kb)
Date: Tue, 8 Apr 2008 22:12:17 GMT (85kb)

Title: Quantum Noise as an Entanglement Meter
Authors: Israel Klich, Leonid Levitov
Categories: quant-ph
   Entanglement entropy, which is a measure of quantum correlations between
separate parts of a many-body system, has emerged recently as a fundamental
quantity in broad areas of theoretical physics, from cosmology and field theory
to condensed matter theory and quantum information. The universal appeal of the
entanglement entropy concept is related, in part, to the fact that it is
defined solely in terms of the many-body density matrix of the system, with no
relation to any particular observables. However, for the same reason, it has
not been clear how to access this quantity experimentally. Here we derive a
universal relation between entanglement entropy and the fluctuations of current
flowing through a quantum point contact (QPC) which opens a way to perform a
direct measurement of entanglement entropy. In particular, by utilizing
space-time duality of 1d systems, we relate electric noise generated by opening
and closing the QPC periodically in time with the seminal S = 1/3 log L
prediction of conformal field theory.
\\ ( , 85kb)
Date: Wed, 9 Apr 2008 10:35:03 GMT (141kb)

Title: Macroscopic Quantum Superposition and Entanglement in light reflection
   from Bose-Einstein Condensates
Authors: Francesco S. Cataliotti and Francesco De Martini
Categories: quant-ph
Comments: 4 pages, 4 figures
   The multiphoton quantum superposition generated by a quantum-injected optical
parametric amplifier (QI-OPA) seeded by a single-photon belonging to an EPR
entangled pair is made to interact with a Mirror-BEC shaped as a Bragg
interference structure. The effect can be greatly enhanced if the mirror is
part of a cavity structure or is used within an optical interferometer. The
overall process will realize an Entangled Macroscopic Quantum Superposition
involving a ''microscopic'' singe-photon state of polarization and the coherent
''macroscopic'' displacement of the BEC structure acting in space-like
separated distant places.
\\ ( , 141kb)
Date: Wed, 9 Apr 2008 18:57:02 GMT (63kb)

Title: Influence of the Radio-Frequency source properties on RF-based atom
Authors: Olivier Morizot (LPL), Laurent Longchambon (LPL), Raghavan Kollengode
   Easwaran (LPL), Romain Dubessy (LPL), Elena Knyazchyan (LPL), Paul-Eric
   Pottie (LPL), Vincent Lorent (LPL), H\'el\`ene Perrin (LPL)
Categories: physics.atom-ph
Comments: 5 figures, 7 pages
Proxy: ccsd hal-00271653
Journal-ref: The European Physical Journal D 47 (2008) 209
DOI: 10.1140/epjd/e2008-00050-2
   We discuss the quality required for the RF source used to trap neutral atoms
in RF-dressed potentials. We illustrate this discussion with experimental
results obtained on a Bose-Einstein condensation experiment with different RF
\\ ( , 63kb)
arXiv:0804.1144 (*cross-listing*)
Date: Mon, 7 Apr 2008 20:52:44 GMT (787kb)

Title: Signatures of Strong Correlations in One-Dimensional Ultra-Cold Atomic
   Fermi Gases
Authors: Paata Kakashvili, S. G. Bhongale, Han Pu and C. J. Bolech
Categories: cond-mat.other cond-mat.str-el physics.atom-ph
Comments: 4 pages, 2 figures
   Recent success in manipulating ultra-cold atomic systems allows to probe
different strongly correlated regimes in one-dimension. Regimes such as the
(spin-coherent) Luttinger liquid and the spin-incoherent Luttinger liquid can
be realized by tuning the inter-atomic interaction strength and trap
parameters. We identify the noise correlations of density fluctuations as a
robust observable (uniquely suitable in the context of trapped atomic gases) to
discriminate between these two regimes. Finally, we address the prospects to
realize and probe these phenomena experimentally using optical lattices.
\\ ( , 787kb)
Date: Wed, 9 Apr 2008 20:00:26 GMT (612kb)

Title: Supersolid state of ultracold fermions in an optical lattice
Authors: Akihisa Koga, Takuji Higashiyama, Kensuke Inaba, Seiichiro Suga, and
   Norio Kawakami
Categories: cond-mat.supr-con
Comments: 4 pages, 4 figures
   We study ultracold fermionic atoms trapped in an optical lattice with
harmonic confinement by means of the dynamical mean-field approximation. It is
demonstrated that a supersolid state, where an s-wave superfluid coexists with
a density-wave state with a checkerboard pattern, is stabilized by attractive
onsite interactions on a square lattice. Our new finding here is that a
confining potential plays an invaluable role in stabilizing the supersolid
state. We establish a rich phase diagram at low temperatures, which clearly
shows how the insulator, the density wave and the superfluid compete with each
other to produce an intriguing domain structure. Our results shed light on the
possibility of the supersolid state in fermionic optical lattice systems.
\\ ( , 612kb)
Date: Thu, 10 Apr 2008 12:17:06 GMT (477kb)

Title: Direct observation of Anderson localization of matter-waves in a
   controlled disorder
Authors: Juliette Billy (LCFIO), Vincent Josse (LCFIO), Zhanchun Zuo (LCFIO),
   Alain Bernard (LCFIO), Ben Hambrecht (LCFIO), Pierre Lugan (LCFIO), David
   Cl\'ement (LCFIO), Laurent Sanchez-Palencia (LCFIO), Philippe Bouyer (LCFIO),
   Alain Aspect (LCFIO)
Categories: cond-mat.dis-nn cond-mat.other
Proxy: ccsd hal-00271681
   We report the observation of exponential localization of a Bose-Einstein
condensate (BEC) released into a one-dimensional waveguide in the presence of a
controlled disorder created by laser speckle . We operate in a regime allowing
AL: i) weak disorder such that localization results from many quantum
reflections of small amplitude; ii) atomic density small enough that
interactions are negligible. We image directly the atomic density profiles vs
time, and find that weak disorder can lead to the stopping of the expansion and
to the formation of a stationary exponentially localized wave function, a
direct signature of AL. Fitting the exponential wings, we extract the
localization length, and compare it to theoretical calculations. Moreover we
show that, in our one-dimensional speckle potentials whose noise spectrum has a
high spatial frequency cut-off, exponential localization occurs only when the
de Broglie wavelengths of the atoms in the expanding BEC are larger than an
effective mobility edge corresponding to that cut-off. In the opposite case, we
find that the density profiles decay algebraically, as predicted in [Phys. Rev.
Lett. 98, 210401 (2007)]. The method presented here can be extended to
localization of atomic quantum gases in higher dimensions, and with controlled
\\ ( , 477kb)
Date: Thu, 10 Apr 2008 12:23:03 GMT (54kb)

Title: Criterion for Bose-Einstein condensation in traps and self-bound systems
Authors: T. Yamada, Y. Funaki, H. Horiuchi, G. Roepke, P. Schuck, and A.
Categories: cond-mat.other
Comments: 15 pages, 1 figure
   The internal one-particle density matrix is discussed for Bose-Einstein
condensates with finite number of particles in a harmonic trap. The outcome of
the digonalization of the density matrix depends on the choice of the internal
coordinates: The Pethick-Pitaevskii-type internal density matrix, whose
analytical eigenvalues and eigenfunctions are evaluated, yields a fragmented
condensate, while the Jacobi-type internal density matrix leads to an ideal
condensate. We give a criterion for the choice of the internal coordinates: In
the macroscopic limit the internal density matrix should have eigenvalues and
eigenfunctions of an ideal Bose-Einstein condensate, this being a very physical
condition for cases where the system is also an ideal Bose condensation in the
laboratory frame. One choice fulfilling this boundary condition is given by the
internal Jacobi coordinates, while the internal coordinates with respect to the
center of mass do not satisfy the condition. Based on our criterion, a general
definition of the internal one-particle density matrix is presented in a
self-bound system, consisting of interacting bosons.
\\ ( , 54kb)
Date: Thu, 10 Apr 2008 12:51:59 GMT (58kb)

Title: Statistical correlations of an anyon liquid at low temperatures
Authors: F. M. D. Pellegrino, G. G. N. Angilella, N. H. March, R. Pucci
Categories: cond-mat.stat-mech cond-mat.mes-hall
Comments: to appear in Phys. Chem. Liquids
   Using a proposed generalization of the pair distribution function for a gas
of non-interacting particles obeying fractional exclusion statistics in
arbitrary dimensionality, we derive the statistical correlations in the
asymptotic limit of vanishing or low temperature. While Friedel-like
oscillations are present in nearly all non-bosonic cases at T=0, they are
characterized by exponential damping at low temperature. We discuss the
dependence of these features on dimensionality and on the value of the
statistical parameter alpha.
\\ ( , 58kb)
Date: Thu, 10 Apr 2008 17:00:32 GMT (220kb)

Title: Trapped Phase-Segregated Bose-Fermi Mixtures and their Collective
Authors: Bert Van Schaeybroeck and Achilleas Lazarides
Categories: cond-mat.stat-mech
Comments: 5 pages, 2 figures
   Recent progress in the field of ultracold gases has allowed the creation of
phase-segregated Bose-Fermi systems. We present a theoretical study of their
collective excitations at zero temperature. Analytically solving the transport
equation for the fully-polarized fermionic phase, we extract the monopole mode
frequencies and their damping rates as a function of the fraction of fermions
in the trap. A criterion for damping to occur, also valid for multipole
excitations, is established. We then use a hydrodynamic approximation for the
fermions to obtain further results concerning in-phase and out-of-phase motions
of the bosonic core and the surrounding fermionic shell.
\\ ( , 220kb)

The replacements:

replaced with revised version Fri, 4 Apr 2008 01:45:29 GMT (0kb,I)

Title: Enhanced quantum Zeno effect and bunching in the decay of interacting
   bosons from an unstable state
Authors: Sungyun Kim, Artem Dudarev and Joachim Brand
Categories: cond-mat.mes-hall
Comments: paper withdrawn by author
\\ ( , 0kb)
replaced with revised version Thu, 3 Apr 2008 22:00:34 GMT (116kb)

Title: Scattering Models for Ultracold Atoms
Authors: Eric Braaten, Masaoki Kusunoki and Dongqing Zhang
Categories: cond-mat.other hep-ph nucl-th
Comments: 60 pages, 6 figures, minor corrections
\\ ( , 116kb)
replaced with revised version Fri, 4 Apr 2008 16:44:01 GMT (11kb)

Title: On entropy growth and the hardness of simulating time evolution
Authors: Norbert Schuch, Michael M. Wolf, Karl Gerd H. Vollbrecht, J. Ignacio
Categories: quant-ph cond-mat.str-el
Comments: 15 pages. v2: Published version, Journal-Ref. added
Journal-ref: New J. Phys. 10, 033032 (2008)
\\ ( , 11kb)
replaced with revised version Fri, 4 Apr 2008 05:44:12 GMT (11kb)

Title: Condition for emergence of complex eigenvalues in the Bogoliubov-de
   Gennes equations
Authors: Y.Nakamura, M.Mine, M.Okumura, and Y.Yamanaka
Categories: cond-mat.other
Comments: 7pages
Journal-ref: Phys. Rev. A 77, 043601 (2008)
DOI: 10.1103/PhysRevA.77.043601
\\ ( , 11kb)
replaced with revised version Fri, 4 Apr 2008 07:52:21 GMT (188kb)

Title: Solitons in two-dimensional Bose-Einstein condensates
Authors: Shunji Tsuchiya, Franco Dalfovo, Lev P. Pitaevskii
Categories: cond-mat.supr-con cond-mat.other
Comments: 4 pages, 4 figures, published version
Journal-ref: Phys. Rev. A 77, 045601 (2008)
\\ ( , 188kb)
replaced with revised version Fri, 4 Apr 2008 07:05:27 GMT (151kb)

Title: Anomalous Enhancement of Quasi-particle Current near a Potential Barrier
   in a BEC
Authors: S. Tsuchiya, Y. Ohashi
Categories: cond-mat.other cond-mat.supr-con
Comments: 4 pages, 3 figures, revised version
\\ ( , 151kb)
replaced with revised version Fri, 4 Apr 2008 19:15:47 GMT (881kb)

Title: The quasi-periodic Bose-Hubbard model and localization in
   one-dimensional cold atomic gases
Authors: G. Roux, T. Barthel, I. P. McCulloch, C. Kollath, U. Schollwoeck, T.
Categories: cond-mat.str-el cond-mat.dis-nn
Comments: 17 pages, 19 figures
\\ ( , 881kb)
replaced with revised version Fri, 4 Apr 2008 16:27:47 GMT (25kb)

Title: Strings, Projected Entangled Pair States, and variational Monte Carlo
Authors: Norbert Schuch, Michael M. Wolf, Frank Verstraete, J. Ignacio Cirac
Categories: quant-ph cond-mat.str-el
Comments: 4 pages. v2: Submitted version, containing more numerical data.
   Changed title and renamed "string states" to "string-bond states" to comply
   with PRL conventions. v3: Accepted version, Journal-Ref. added (title differs
   from journal)
Journal-ref: Phys. Rev. Lett. 100, 040501 (2008)
\\ ( , 25kb)
replaced with revised version Sun, 6 Apr 2008 13:32:42 GMT (348kb)

Title: Heteronuclear molecules in an optical lattice: Theory and experiment
Authors: Frank Deuretzbacher, Kim Plassmeier, Daniela Pfannkuche, F\'elix
   Werner, Christian Ospelkaus, Silke Ospelkaus, Klaus Sengstock, Kai Bongs
Categories: cond-mat.other physics.atom-ph
Comments: 9 pages, 7 figures, revised discussion of transfer efficiency
Journal-ref: Phys. Rev. A 77, 032726 (2008)
DOI: 10.1103/PhysRevA.77.032726
\\ ( , 348kb)
replaced with revised version Mon, 7 Apr 2008 12:51:48 GMT (9kb)

Title: Correlations in an expanding gas of hard-core bosons
Authors: D. M. Gangardt, M. Pustilnik
Categories: cond-mat.stat-mech cond-mat.other
\\ ( , 9kb)
replaced with revised version Mon, 7 Apr 2008 18:53:10 GMT (111kb)

Title: Dipolar bosons in a planar array of one-dimensional tubes
Authors: C. Kollath, Julia S. Meyer, T. Giamarchi
Categories: cond-mat.other cond-mat.str-el
Journal-ref: Phys. Rev. Lett. 100, 130403 (2008)
DOI: 10.1103/PhysRevLett.100.130403
\\ ( , 111kb)
replaced with revised version Mon, 7 Apr 2008 09:55:09 GMT (416kb)

Title: Damped Bloch Oscillations of Bose-Einstein Condensates in Disordered
   Potential Gradients
Authors: S. Drenkelforth, G. Kleine B\"uning, J. Will, T. Schulte, N. Murray,
   W. Ertmer, L. Santos, and J.J. Arlt
Categories: cond-mat.other
Comments: to be published in New Journal of Physics
\\ ( , 416kb)
replaced with revised version Mon, 7 Apr 2008 19:29:32 GMT (42kb)

Title: Stability of Superflow for Ultracold Fermions in Optical Lattices
Authors: A.A. Burkov, Arun Paramekanti
Categories: cond-mat.supr-con cond-mat.str-el
Comments: 4+ pages, 2 figures
\\ ( , 42kb)
replaced with revised version Sun, 6 Apr 2008 21:41:50 GMT (969kb,D)

Title: Stochastic Mean-Field Theory for the Disordered Bose-Hubbard Model
Authors: U. Bissbort, W. Hofstetter
Categories: cond-mat.dis-nn cond-mat.other
Comments: 4 pages, 5 figures
\\ ( , 969kb)
replaced with revised version Mon, 7 Apr 2008 08:25:43 GMT (493kb)

Title: Quantum-limited position measurements of a dark matter-wave soliton
Authors: Antonio Negretti, Carsten Henkel, and Klaus Molmer
Categories: quant-ph
Comments: RevTex4, 5 pages, 1 figure
Journal-ref: Phys. Rev. A 77, 043606 (2008)
DOI: 10.1103/PhysRevA.77.043606
\\ ( , 493kb)
replaced with revised version Tue, 8 Apr 2008 15:50:56 GMT (40kb)

Title: Engineering many-body quantum dynamics by disorder
Authors: Pierfrancesco Buonsante and Sandro Wimberger
Categories: cond-mat.dis-nn cond-mat.stat-mech
Comments: 4 pages, 4 figures (improved version), to be published in PRA
\\ ( , 40kb)
replaced with revised version Wed, 9 Apr 2008 19:29:08 GMT (7kb)

Title: Casimir Friction II: Casimir effect and drag in zero temperature
Authors: D. C. Roberts and Y. Pomeau
Categories: cond-mat.stat-mech
Comments: To appear in Modern Encyclopedia of Mathematical Physics (MEMPhys);
   companion article to arXiv:0704.2194; v5 - corrected boundary condition,
   other minor editorial changes
\\ ( , 7kb)
replaced with revised version Wed, 9 Apr 2008 08:34:01 GMT (149kb)

Title: Dephasing and the steady state in quantum many-particle systems
Authors: Thomas Barthel, Ulrich Schollw\"ock
Categories: cond-mat.stat-mech
Comments: 4 pages, 3 figures, minor changes
Journal-ref: Phys. Rev. Lett. 100, 100601 (2008)
DOI: 10.1103/PhysRevLett.100.100601
\\ ( , 149kb)

Till next time,

Dr M. J. Davis,               Senior Lecturer in Physics
School of Physical Sciences,  email:
University of Queensland,     ph   : +61 7 334 69824
Brisbane, QLD 4072,           fax  : +61 7 336 51242
Matt's arXiv selection: weekly summary of cold-atom papers from
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 Thu May 08 2008 - 11:45:46 EST

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