Matt's arXiv selection: week ending 31 October 2008

From: Matthew Davis <>
Date: Thu, 06 Nov 2008 21:15:48 +1000

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

Hello again,

This week there were 30 new preprints and 16 replacements:

Date: Fri, 24 Oct 2008 00:29:46 GMT (342kb)

Title: Testing of spin ordering Hamiltonian with ultracold atoms in optical
Authors: G. E. Akpojotor and W. Li
Categories: cond-mat.str-el
   Laser cooling and trapping are now widely used in atomic physics laboratory.
Interestingly, cold atoms in optical lattices are now used in advanced research
to mimic phenomena in condensed matter physics and also as a test laboratory
for the models of these phenomena. It follows then that it is now possible and
necessary to advance the atomic physics laboratory by including the use of
ultracold atoms in optical lattices for instructional contents of phenomena in
condensed matter physics. In this paper, we have proposed how to introduce into
the atomic physics laboratory the study of quantum magnetism with cold atoms in
a double well optical lattice. In particular, we demonstrates how to compare
the theoretical parameters of a spin Hamiltonian model with those extracted
from spin ordering experiment.
\\ ( , 342kb)
Date: Fri, 24 Oct 2008 08:35:01 GMT (685kb)

Title: Rapidly Rotating Atomic Gases
Authors: N. R. Cooper
Categories: cond-mat.mes-hall
Comments: Submitted for publication in Advances in Physics
   This article reviews developments in the theory of rapidly rotating
degenerate atomic gases. The main focus is on the equilibrium properties of a
single component atomic Bose gas, which (at least at rest) forms a
Bose-Einstein condensate. Rotation leads to the formation of quantized vortices
which order into a vortex array, in close analogy with the behaviour of
superfluid helium. Under conditions of rapid rotation, when the vortex density
becomes large, atomic Bose gases offer the possibility to explore the physics
of quantized vortices in novel parameter regimes. First, there is an
interesting regime in which the vortices become sufficiently dense that their
cores -- as set by the healing length -- start to overlap. In this regime, the
theoretical description simplifies, allowing a reduction to single particle
states in the lowest Landau level. Second, one can envisage entering a regime
of very high vortex density, when the number of vortices becomes comparable to
the number of particles in the gas. In this regime, theory predicts the
appearance of a series of strongly correlated phases, which can be viewed as
{\it bosonic} versions of fractional quantum Hall states. This article
describes the equilibrium properties of rapidly rotating atomic Bose gases in
both the mean-field and the strongly correlated regimes, and related
theoretical developments for Bose gases in lattices, for multi-component Bose
gases, and for atomic Fermi gases. The current experimental situation and
outlook for the future are discussed in the light of these theoretical
\\ ( , 685kb)
Date: Fri, 24 Oct 2008 08:41:30 GMT (54kb)

Title: Green's Function Approach to the Bose-Hubbard Model
Authors: Matthias Ohliger, Axel Pelster
Categories: cond-mat.stat-mech
   We use a diagrammatic hopping expansion to calculate finite-temperature Green
functions of the Bose-Hubbard model which describes bosons in an optical
lattice. This technique allows for a summation of subsets of diagrams, so the
divergence of the Green function leads to non-perturbative results for the
boundary between the superfluid and the Mott phase for finite temperatures.
Whereas the first-order calculation reproduces the seminal mean-field result,
the second order goes beyond and shifts the phase boundary in the immediate
vicinity of the critical parameters determined by the latest high-precision
Monte-Carlo simulations of the Bose-Hubbard model. In addition, our Green's
function approach allows for calculating the excitation spectrum at finite
temperature and for determining the effective masses of particles and holes.
\\ ( , 54kb)
Date: Fri, 24 Oct 2008 09:03:00 GMT (633kb)

Title: Topologically trapped vortex molecules in Bose-Einstein condensates
Authors: R. Geurts, M. V. Milo\v{s}evi\'c, F. M. Peeters
Categories: cond-mat.other
Comments: 5 pages, 4 figures
   In a numerical experiment based on Gross-Pitaevskii formalism, we demonstrate
unique topological quantum coherence in optically trapped Bose-Einstein
condensates (BECs). Exploring the fact that vortices in rotating BEC can be
pinned by a geometric arrangement of laser beams, we show the parameter range
in which vortex-antivortex molecules or multiquantum vortices are formed as a
consequence of the optically imposed symmetry. Being low-energy states, we
discuss the conditions for spontaneous nucleation of these unique molecules and
their direct experimental observation, and provoke the potential use of the
phase print of an antivortex or a multiquantum vortex when realized in
unconventional circumstances.
\\ ( , 633kb)
Date: Fri, 24 Oct 2008 09:11:47 GMT (188kb)

Title: Compression as a tool to detect Bose glass in cold atoms experiments
Authors: Dominique Delande and Jakub Zakrzewski
Categories: cond-mat.dis-nn cond-mat.other
Comments: 4pp. 4figs
   We suggest that measuring the variation of the radius of an atomic cloud when
the harmonic tap confinement is varied make it possible to monitor the
disappearance of the insulating Mott phase of an ultracold atomic gas trapped
in a disordered optical lattice. This paves the way for an unambiguous
identification of a Bose glass phase in the system.
\\ ( , 188kb)
Date: Fri, 24 Oct 2008 15:10:03 GMT (388kb)

Title: Thermodynamical approaches to efficient sympathetic cooling in ultracold
   Fermi-Bose atomic mixtures
Authors: Michael Brown-Hayes, Qun Wei, Carlo Presilla, Roberto Onofrio
Categories: cond-mat.supr-con cond-mat.stat-mech
Comments: 13 pages, 9 figures, higher quality figures in published version
Journal-ref: Phys. Rev. A 78, 013617 (2008)
   We discuss the cooling efficiency of ultracold Fermi-Bose mixtures in
species-selective traps using a thermodynamical approach. The dynamics of
evaporative cooling trajectories is analyzed in the specific case of
bichromatic optical dipole traps also taking into account the effect of partial
spatial overlap between the Fermi gas and the thermal component of the Bose
gas. We show that large trapping frequency ratios between the Fermi and the
Bose species allow for the achievement of a deeper Fermi degeneracy,
consolidating in a thermodynamic setting earlier arguments based on more
restrictive assumptions. In particular, we confirm that the minimum temperature
of the mixture is obtained at the crossover between boson and fermion heat
capacities, and that below such a temperature sympathetic cooling vanishes.
When the effect of partial overlap is taken into account, optimal sympathetic
cooing of the Fermi species may be achieved by properly tuning the relative
trapping strength of the two species in a time-dependent fashion.
Alternatively, the dimensionality of the trap in the final stage of cooling can
be changed by increasing the confinement strength, which also results in a
crossover of the heat capacities at deeper Fermi degeneracies. This technique
may be extended to Fermi-Bose degenerate mixtures in optical lattices.
\\ ( , 388kb)
Date: Fri, 24 Oct 2008 16:19:17 GMT (34kb)

Title: Cooling ultracold bosons in optical lattices by spectral transform
Authors: David L. Feder
Categories: cond-mat.stat-mech
Comments: 13+e pages, two embedded figures, revtex
   It is shown theoretically how to directly obtain the energy distribution of a
weakly interacting gas of bosons confined in an optical lattice in the
tight-binding limit. This is accomplished by adding a linear potential to a
suitably prepared lattice, and allowing the gas to evolve under the influence
of the total potential. After a prescribed time, a spectral transform is
effected where each (highly non-local) energy state is transformed into a
distinct site of the lattice, thus allowing the energy distribution to be
(non-destructively) imaged in real space. Evolving for twice the time returns
the atoms to their initial state. The results suggest efficient methods to both
measure the temperature in situ, as well as to cool atoms within the lattice:
after applying the spectral transform one simply needs to remove atoms from all
but a few lattice sites. Using exact numerical calculations, the effects of
interactions and errors in the application of the lattice are examined.
\\ ( , 34kb)
Date: Fri, 24 Oct 2008 15:34:34 GMT (149kb)

Title: Optical Lenses for Atomic Beams
Authors: Ole Steuernagel
Categories: quant-ph physics.optics
Comments: 10 figures
   Superpositions of paraxial laser beam modes to generate atom-optical lenses
based on the optical dipole force are investigated theoretically. Thin, wide,
parabolic, cylindrical and circular atom lenses with numerical apertures much
greater than those reported in the literature to date can be synthesized. This
superposition approach promises to make high quality atom beam imaging and
nano-deposition feasible.
\\ ( , 149kb)
Date: Fri, 24 Oct 2008 14:21:09 GMT (249kb)

Title: Collisional decoherence in trapped atom interferometer that use
   non-degenerate sources
Authors: James A. Stickney, Matthew B. Squires, James Scoville, Paul Baker, and
   Steven Miller
Categories: physics.atom-ph
Comments: (23 pages, 5 figures)
   The coherence time, and thus sensitivity, of trapped atom interferometers
that use non-degenerate gasses are limited by the collisions between the atoms.
An analytic model that describes the effects of collisions between atoms in an
interferometer is developed. It is then applied to an interferometer using a
harmonically trapped non-degenerate atomic gas that is manipulated with a
single set of standing wave laser pulses. The model is used to find the optimal
operating conditions of the interferometer and direct Monte-Carlo simulation of
the interferometer is used to verify the analytic model.
\\ ( , 249kb)
Date: Fri, 24 Oct 2008 14:40:05 GMT (171kb)

Title: Stochastic optimization of a cold atom experiment using a genetic
Authors: Wolfgang Rohringer, Robert Buecker, Stephanie Manz, Thomas Betz,
   Christian Koller, Martin Goebel, Aurelien Perrin, Joerg Schmiedmayer,
   Thorsten Schumm
Categories: physics.atom-ph
Comments: 4 pages, 3 figures
   We employ an evolutionary algorithm to automatically optimize different
stages of a cold atom experiment without human intervention. This approach
closes the loop between computer based experimental control systems and
automatic real time analysis and can be applied to a wide range of experimental
situations. The genetic algorithm quickly and reliably converges to the most
performing parameter set independent of the starting population. Especially in
many-dimensional or connected parameter spaces the automatic optimization
outperforms a manual search.
\\ ( , 171kb)
Date: Sun, 26 Oct 2008 23:51:46 GMT (1484kb,D)

Title: Introduction to Quantum Noise, Measurement and Amplification
Authors: A. A. Clerk, M. H. Devoret, S. M. Girvin, F. Marquardt, R. J.
Categories: cond-mat.mes-hall
Comments: To be submitted to Reviews of Modern Physics; 102 pages
   The topic of quantum noise has become extremely timely due to the rise of
quantum information physics and the resulting interchange of ideas between the
condensed matter and AMO/quantum optics communities. This review gives a
pedagogical introduction to the physics of quantum noise and its connections to
quantum measurement and quantum amplification. After introducing quantum noise
spectra and methods for their detection, we describe the basics of weak
continuous measurements. Particular attention is given to treating the standard
quantum limit on linear amplifiers and position detectors using a general
linear-response framework. We show how this approach relates to the standard
Haus-Caves quantum limit for a bosonic amplifier known in quantum optics, and
illustrate its application for the case of electrical circuits, including
mesoscopic detectors and resonant cavity detectors.
\\ ( , 1484kb)
Date: Mon, 27 Oct 2008 17:24:39 GMT (28kb)

Title: Density and spin response function of a normal Fermi gas at unitarity
Authors: S. Stringari
Categories: cond-mat.stat-mech
Comments: 4 pages, 2 figures
   Using Landau theory of Fermi liquids we calculate the dynamic response of
both a polarized and unpolarized normal Fermi gas at zero temperature in the
strongly interacting regime of large scattering length. We show that at small
excitation energies the {\it in phase} (density) response is enhanced with
respect to the ideal gas prediction due to the increased compressibility.
Viceversa, the {\it out of phase} (spin) response is quenched as a consequence
of the tendency of the system to pair opposite spins. The long wavelength
behavior of the static structure factor is explicitly calculated. The results
are compared with the predictions in the collisional and superfluid regimes.
The emergence of a spin zero sound solution in the unpolarized normal phase is
explicitly discussed.
\\ ( , 28kb)
Date: Mon, 27 Oct 2008 10:00:38 GMT (308kb)

Title: Pairing in fermionic systems: A quantum information perspective
Authors: Christina V. Kraus, Michael M. Wolf, J. Ignacio Cirac, Geza Giedke
Categories: quant-ph
Comments: 23 pages, 4 figures
   The notion of "paired" fermions is central to important condensed matter
phenomena such as superconductivity and superfluidity. While the concept is
widely used and its physical meaning is clear there exists no systematic and
mathematical theory of pairing which would allow to unambiguously characterize
and systematically detect paired states. We propose a definition of pairing and
develop methods for its detection and quantification applicable to current
experimental setups. Pairing is shown to be a quantum correlation different
from entanglement, giving further understanding in the structure of highly
correlated quantum systems. In addition, we will show the resource character of
paired states for precision metrology, proving that the BCS states allow phase
measurements at the Heisenberg limit.
\\ ( , 308kb)
Date: Tue, 28 Oct 2008 06:59:27 GMT (236kb,D)

Title: Rotating Fermi gases in an anharmonic trap
Authors: Kiel Howe, Aristeu R. P. Lima, Axel Pelster
Categories: cond-mat.stat-mech
   Motivated by recent experiments on rotating Bose-Einstein condensates, we
investigate a rotating, polarized Fermi gas trapped in an anharmonic potential.
We apply a semiclassical expansion of the density of states in order to
determine how the thermodynamic properties depend on the rotation frequency.
The accuracy of the semiclassical approximation is tested and shown to be
sufficient for describing typical experiments. At zero temperature, rotating
the gas above a given frequency $\Omega_{\rm DO}$ leads to a `donut'-shaped
cloud which is analogous to the hole found in two-dimensional Bose-Einstein
condensates. The free expansion of the gas after suddenly turning off the trap
is considered and characterized by the time and rotation frequency dependence
of the aspect ratio. Temperature effects are also taken into account and both
low- and high-temperature expansions are presented for the relevant
thermodynamical quantities. In the high-temperature regime a virial theorem
approach is used to study the delicate interplay between rotation and
\\ ( , 236kb)
Date: Tue, 28 Oct 2008 14:54:47 GMT (70kb)

Title: Superfluid Bose-Fermi mixture from weak-coupling to unitarity
Authors: S. K. Adhikari and Luca Salasnich
Categories: cond-mat.other
Comments: 11 pages
   We investigate the zero-temperature properties of a superfluid Bose-Fermi
mixture by introducing a set of coupled Galilei-invariant nonlinear
Schr\"odinger equations valid from weak-coupling to unitarity. The Bose
dynamics is described by a Gross-Pitaevskii-type equation including
beyond-mean-field corrections possessing the correct weak-coupling and
unitarity limits. The dynamics of the two-component Fermi superfluid is
described by a density-functional equation including beyond-mean-field terms
with correct weak-coupling and unitarity limits. The present set of equations
is equivalent to the equations of generalized superfluid hydrodynamics, which
take into account also surface effects. The equations describe the mixture
properly as the Bose-Bose repulsive (positive) and Fermi-Fermi attractive
(negative) scattering lengths are varied from zero to infinity in the presence
of a Bose-Fermi interaction. The present model is tested numerically as the
Bose-Bose and Fermi-Fermi scattering lengths are varied over wide ranges
covering the weak-coupling to unitarity transition.
\\ ( , 70kb)
Date: Tue, 28 Oct 2008 16:01:42 GMT (26kb)

Title: Trapped fermion mixtures with unequal masses: a Bogoliubov-de Gennes
Authors: M. Iskin and C. J. Williams
Categories: cond-mat.supr-con cond-mat.other
Comments: 4+ pages and 3 figures
   We use the Bogoliubov-de Gennes formalism to analyze the ground state phases
of harmonically trapped two-species fermion mixtures with unequal masses. In
the weakly attracting limit and around unitarity, we find that the superfluid
order parameter is spatially modulated around the trap center, and that its
global maximum occurs at a finite distance away from the trap center where the
mixture is locally unpolarized. As the attraction strength increases towards
the molecular limit, the spatial modulations gradually disappear while the
Bardeen-Cooper-Schrieffer (BCS) type nonmodulated superfluid region expands
until the entire mixture becomes locally unpolarized.
\\ ( , 26kb)
Date: Tue, 28 Oct 2008 16:54:22 GMT (26kb)

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
   The interplay between magnetism and metal-insulator transitions is
fundamental to the rich physics of the single band fermion Hubbard model (FHM).
Recent progress in experiments on trapped ultra-cold atoms have made possible
the exploration of similar effects in the boson Hubbard model (BHM). This paper
reports Quantum Monte Carlo (QMC) simulations of the spin-1 BHM in the ground
state. In the case of antiferromagnetic interactions, which favor singlet
formation within the Mott insulator lobes, we present exact numerical evidence
that the superfluid-insulator phase transition is first (second) order
depending on whether the Mott lobe is even (odd). In the ferromagnetic case,
the transitions are all continuous. We obtain the phase diagram in the case of
attractive spin interactions and demonstrate the existence of the ferromagnetic
superfluid. We also compare the QMC phase diagram with a third order
perturbation calculation.
\\ ( , 26kb)
arXiv:0810.4874 (*cross-listing*)
Date: Mon, 27 Oct 2008 17:44:21 GMT (27kb)

Title: On the Mathematical Theory of Superfluidity
Authors: Geoffrey L. Sewell and Walter F. Wreszinski
Categories: math-ph cond-mat.stat-mech math.MP
Comments: To be published in J. Phys. A
   We provide a general operator algebraic formulation of superfluidity in Bose
systems, with the aim of investigating the relationships of this phenomenon
both to off-diagonal long range order (ODLRO) and to a mathematically precise
version of Landau's picture of elementary excitations. Our principal resulta
are that ODLRO leads both to rotational superfluidity and to Goldstone
excitations, while the neo-Landau picture accounts for the translational
superfluidity of flow along a pipe. The latter picture is realised by the
Lieb-Liniger-Girardeau model. Open problems are briefly discussed.
\\ ( , 27kb)
Date: Tue, 28 Oct 2008 03:36:16 GMT (941kb)

Title: Reality, locality and all that: "experimental metaphysics" and the
   quantum foundations
Authors: Eric G. Cavalcanti
Categories: quant-ph
Comments: PhD thesis, The University of Queensland. Awarded May 2008
   In recent decades there has been a resurge of interest in the foundations of
quantum theory, partly motivated by new experimental techniques, partly by the
emerging field of quantum information science. Old questions, asked since the
seminal article by Einstein, Podolsky and Rosen (EPR), are being revisited. The
work of John Bell has changed the direction of investigation by recognising
that those fundamental philosophical questions can have, after all, input from
experiment. Abner Shimony has aptly termed this new field of enquiry
"experimental metaphysics". The objective of this Thesis is to contribute to
that body of research, by formalising old concepts, proposing new ones, and
finding new results in well-studied areas. Without losing from sight that the
appeal of experimental metaphysics comes from the adjective, every major result
is followed by clear experimental proposals for quantum-atom optical setups.
\\ ( , 941kb)
Date: Tue, 28 Oct 2008 15:55:05 GMT (428kb)

Title: Velocity distribution measurements in atomic beams generated using laser
   induced back-ablation
Authors: A. Denning, A. Booth, S. Lee, M. Ammonson, and S. D. Bergeson
Categories: physics.atom-ph
Comments: 4 pages, 3 figures
   We present measurements of the velocity distribution of calcium atoms in an
atomic beam generated using a dual-stage laser back-ablation apparatus.
Distributions are measured using a velocity selective Doppler time-of-flight
technique. They are Boltzmann-like with rms velocities corresponding to
temperatures above the melting point for calcium. Contrary to a recent report
in the literature, this method does not generate a sub-thermal atomic beam.
\\ ( , 428kb)
Date: Tue, 28 Oct 2008 22:21:19 GMT (2334kb,D)

Title: Atomic three-body loss as a dynamical three-body interaction
Authors: A. J. Daley, J. M. Taylor, S. Diehl, M. Baranov, P. Zoller
Categories: cond-mat.other
Comments: 4 pages, 4 figures
   We discuss how large three-body loss of atoms in an optical lattice can give
rise to effective hard-core three-body interactions. For bosons, in addition to
the usual atomic superfluid, a dimer superfluid can then be observed for
attractive two-body interactions. The non-equilibrium dynamics of preparation
and stability of these phases are studied in 1D by combining time-dependent
Density Matrix Renormalisation Group techniques with a quantum trajectories
\\ ( , 2334kb)
Date: Wed, 29 Oct 2008 05:11:09 GMT (156kb)

Title: Dynamics and modulation of ring dark soliton in 2D Bose-Einstein
   condensates with tunable interaction
Authors: Xing-Hua Hu, Xiao-Fei Zhang, Dun Zhao, Hong-Gang Luo, and W. M. Liu
Categories: cond-mat.other
Comments: 6 pages, 4 figures
   We investigate the dynamics and modulation of ring dark soliton in 2D
Bose-Einstein condensates with tunable interaction both analytically and
numerically. The analytic solutions of ring dark soliton are derived by using a
new transformation method. For shallow ring dark soliton, it is stable when the
ring is slightly distorted, while for large deformation of the ring, vortex
pairs appear and they demonstrate novel dynamical behaviors: the vortex pairs
will transform into dark lumplike solitons and revert to ring dark soliton
periodically. Moreover, our results show that the dynamical evolution of the
ring dark soliton can be dramatically affected by Feshbach resonance, and the
lifetime of the ring dark soliton can be largely extended which offers a useful
method for observing the ring dark soliton in future experiments.
\\ ( , 156kb)
Date: Wed, 29 Oct 2008 07:54:14 GMT (94kb,D)

Title: Photonic Hall effect in cold atomic clouds
Authors: Beno\^it Gr\'emaud, Dominique Delande, Olivier Sigwarth, Christian
Categories: cond-mat.mes-hall cond-mat.dis-nn
Comments: 4 pages 4 figures
   On the basis of exact numerical simulations and analytical calculations, we
describe qualitatively and quantitatively the interference processes at the
origin of the photonic Hall effect for resonant Rayleigh (point-dipole)
scatterers in a magnetic field. For resonant incoming light, the induced giant
magneto-optical effects result in relative Hall currents in the percent range,
three orders of magnitude larger than with classical scatterers. This suggests
that the observation of the photonic Hall effect in cold atomic vapors is
within experimental reach.
\\ ( , 94kb)
Date: Wed, 29 Oct 2008 13:28:27 GMT (327kb)

Title: Vortex-lattice pinning in two-component Bose-Einstein condensates
Authors: M. P. Mink, C. Morais Smith, and R. A. Duine
Categories: cond-mat.mes-hall
   We investigate the vortex-lattice structure for single- and two-component
Bose-Einstein condensates in the presence of an optical lattice, which acts as
a pinning potential for the vortices. The problem is considered in the
mean-field quantum-Hall regime, which is reached when the rotation frequency
$\Omega$ of the condensate in a radially symmetric trap approaches the (radial)
trapping frequency $\omega$ and the interactions between the atoms are weak. We
determine the vortex-lattice phase diagram as a function of optical-lattice
strength and geometry. In the limit of strong pinning the vortices are always
pinned at the maxima of the optical-lattice potential, similar to the
slow-rotation case. At intermediate pinning strength, however, due to the
competition between interactions and pinning energy, a structure arises for the
two-component case where the vortices are pinned on lines of minimal potential.
\\ ( , 327kb)
Date: Thu, 30 Oct 2008 08:52:53 GMT (902kb)

Title: Supersolid phases of hardcore bosons on the square lattice: Correlated
   hopping, next-nearest neighbor hopping and frustration
Authors: F. Mila, J. Dorier, and K.P. Schmidt
Categories: cond-mat.str-el
Comments: 20 pages, 15 figures, to be published in the proceedings of YKIS2007
   conference as a special issue of Prog. Theor. Phys. Suppl
   We discuss the appearance of supersolid phases for interacting hardcore
bosons on the square lattice when, in addition to the standard nearest neighbor
hopping and repulsion, correlated or next-nearest neighbor hopping is present.
Having in mind dimer-based quantum magnets in a field described by effective
bosonic models of this kind, we put special emphasis on a comparison between
the different cases of relative signs of the kinetic processes, which
correspond to unfrustrated or frustrated magnetic models. In the unfrustrated
case, we compare Quantum Monte Carlo simulations with a mean-field (classical)
approach, which is shown to give qualitatively correct results. Using this
classical approach for the frustrated case, we find that the phase diagram is
generically richer than in the unfrustrated case. We also investigate in detail
the differences between standard next-nearest neighbour and correlated hopping
over the diagonal, with the conclusion that both cases are similar if
checkerboard order is present at half-filling, while a supersolid phase can be
stabilized without any adjacent solid phase only in the case of correlated
\\ ( , 902kb)
Date: Thu, 30 Oct 2008 15:10:57 GMT (439kb)

Title: Determination of atomic scattering lengths from measurements of
   molecular binding energies near Feshbach resonances
Authors: A. D. Lange, K. Pilch, A. Prantner, F. Ferlaino, B. Engeser, H.-C.
   Naegerl, R. Grimm, and C. Chin
Categories: cond-mat.other
Comments: 6 pages, 4 figures
   We present an analytic model to calculate the atomic scattering length near a
Feshbach resonance from data on the molecular binding energy. Our approach
considers finite-range square-well potentials and can be applied near broad,
narrow, or even overlapping Feshbach resonances. We test our model on Cs$_2$
Feshbach molecules. We measure the binding energy using magnetic-field
modulation spectroscopy in a range where one broad and two narrow Feshbach
resonances overlap. From the data we accurately determine the Cs atomic
scattering length and the positions and widths of two particular resonances.
\\ ( , 439kb)
Date: Thu, 30 Oct 2008 19:08:50 GMT (1412kb,D)

Title: Reconnection Dynamics for Quantized Vortices
Authors: M. S. Paoletti, Michael E. Fisher, and D. P. Lathrop
Categories: cond-mat.stat-mech cond-mat.supr-con
Comments: 12 pages, 13 figures, submitted to Physica D special topics: Fluid
   Science and Turbulence
   By analyzing trajectories of solid hydrogen tracers in superfluid $^4$He, we
identify tens of thousands of individual reconnection events between quantized
vortices. We characterize the dynamics by the minimum separation distance
$\delta(t)$ between the two reconnecting vortices both before and after the
events. Applying dimensional arguments, this separation has been predicted to
behave asymptotically as $\delta(t) \approx A(\kappa |t-t_0|)^{1/2}$, where
$\kappa=h/m$ is the quantum of circulation. The major finding of the
experiments and their analysis is strong support for this asymptotic form with
$\kappa$ as the dominant controlling feature, although there are significant
event to event fluctuations. At the three-parameter level the dynamics may be
about equally well-fit by two modified expressions: (a) an arbitrary power-law
expression of the form $\delta(t)=B|t-t_0|^{\alpha}$ and (b) a
correction-factor expression $\delta(t)=A(\kappa|t-t_0|)^{1/2}(1+c|t-t_0|)$. In
light of possible physical interpretations we regard the correction-factor
expression (b), which attributes the observed deviations from the predicted
asymptotic form to fluctuations in the local environment and in boundary
conditions, as best describing our experimental data. The observed dynamics
appear statistically time-reversible, which suggests that an effective
equilibrium has been established in quantum turbulence on the time scales
investigated. We discuss the impact of reconnection on velocity statistics in
quantum turbulence and, as regards classical turbulence, we argue that forms
analogous to (b) could well provide an alternative interpretation of the
observed deviations from Kolmogorov scaling exponents of the longitudinal
structure functions.
\\ ( , 1412kb)
Date: Thu, 30 Oct 2008 15:10:47 GMT (699kb)

Title: The effect of dipole-dipole interaction for two atoms with different
   couplings in non-Markovian environment
Authors: Yang Li, Jiang Zhou, and Hong Guo
Categories: quant-ph
Comments: 6 pages, 2 figures
   Using the nonperturbative method, we study the exact entanglement dynamics of
two two-level dipole-dipole interacting atoms coupled to a common non-Markovian
reservoir with different coupling strengths. Besides analyzing the conditions
for the existence of steady state, we find, though the dipole-dipole
interaction could destroy the stationary entanglement, that relatively strong
dipole-dipole interaction does suppress the disentanglement in the initial
period of time. These results are helpful for the practical engineering of the
entanglement in the future.
\\ ( , 699kb)
Date: Thu, 30 Oct 2008 07:17:00 GMT (344kb)

Title: Investigation of cold Rb Rydberg atoms in a magneto-optical trap
Authors: D.B.Tretyakov, I.I.Beterov, V.M.Entin, I.I.Ryabtsev, and P.L.Chapovsky
Categories: physics.atom-ph
Comments: 9 pages, 6 figures. To appear in JETP, 2009
   We present our results on the experiments with cold Rb Rydberg atoms in a
magneto-optical trap (MOT). Characteristic features of our experiment were the
excitation of Rydberg atoms in a small volume within the cold atom cloud and
sorting of the measured signals and spectra over the number of registered
Rydberg atoms. We have measured the effective lifetime of the Rydberg state
37P, as well as its polarizability in a weak electric field. The results are in
good agreement with the theoretical calculations. We have shown that
localization of the small excitation volume around the zero-magnetic-field
point makes possible to increase the spectral resolution and to obtain narrow
microwave resonances in Rydberg atoms without switching off the MOT quadrupole
magnetic field. We have measured the dependence of the amplitude of the
dipole-dipole interaction resonances on the number of Rydberg atoms, which has
a linear character and agrees with the theory for weak dipole-dipole
\\ ( , 344kb)
Date: Thu, 30 Oct 2008 15:13:07 GMT (395kb)

Title: Gap solitons on a ring
Authors: Yaroslav V. Kartashov, Boris A. Malomed, Victor A. Vysloukh, Lluis
Categories: physics.optics
Comments: 13 pages, 4 figures, to appear in Optics Letters
   We introduce a new species of gap solitons (GSs) supported by an azimuthally
modulated guiding ring in defocusing cubic media. The periodicity in the
azimuthal direction strongly modifies properties and existence domains of GSs.
In addition to the fundamental solitons, we report even and twisted bound
states. The former type is found to be stable, while the twisted states are
always unstable in defocusing media.
\\ ( , 395kb)

The replacements:

replaced with revised version Fri, 24 Oct 2008 07:07:41 GMT (392kb,D)

Title: Solids and supersolids of three-body interacting polar molecules in an
   optical lattice
Authors: Kai P. Schmidt, Julien Dorier, Andreas Laeuchli
Categories: cond-mat.str-el cond-mat.stat-mech
Comments: 4+ pages, 4 figures, published version
Journal-ref: Phys. Rev. Lett. 101, 150405 (2008)
DOI: 10.1103/PhysRevLett.101.150405
\\ ( , 392kb)
replaced with revised version Fri, 24 Oct 2008 14:07:31 GMT (323kb)

Title: Finite temperature coherence of the ideal Bose gas in an optical lattice
Authors: G.A. Muradyan and J.R. Anglin
Categories: cond-mat.stat-mech
\\ ( , 323kb)
replaced with revised version Fri, 24 Oct 2008 01:35:13 GMT (390kb)

Title: Controlling atomic vapor density in paraffin-coated cells using
   light-induced atomic desorption
Authors: T. Karaulanov, M. T. Graf, D. English, S. M. Rochester, Y. Rosen, K.
   Tsigutkin, D. Budker, E. B. Alexandrov, M. V. Balabas, D. F. Jackson Kimball,
   F. A. Narducci, S. Pustelny, V. V. Yashchuk
Categories: physics.atom-ph
Comments: 10 pages, 11 figures
\\ ( , 390kb)
replaced with revised version Mon, 27 Oct 2008 11:25:14 GMT (170kb)

Title: Cold Fermionic Atoms in Two-Dimensional Traps -- Pairing versus Hund's
Authors: M. Rontani, J. Armstrong, Y. Yu, S. {\AA}berg, S. M. Reimann
Categories: cond-mat.mes-hall
Comments: RevTeX 4.0, 5 pages, 5 colour postscript figures
\\ ( , 170kb)
replaced with revised version Mon, 27 Oct 2008 19:08:22 GMT (941kb)

Title: Effective Action Approach for Quantum Phase Transitions in Bosonic
Authors: Barry Bradlyn, Francisco Ednilson A. dos Santos, Axel Pelster
Categories: cond-mat.stat-mech
Comments: Phys. Rev. A (in press)
\\ ( , 941kb)
replaced with revised version Sat, 25 Oct 2008 08:29:33 GMT (2871kb,D)
replaced with revised version Mon, 27 Oct 2008 23:16:49 GMT (74kb)

Title: Theory of spin nematic to spin-Peierls quantum phase transition in
   ultracold spin-1 atoms in optical lattices
Authors: Christoph M. Puetter, Michael J. Lawler, Hae-Young Kee
Categories: cond-mat.str-el
Comments: 7 pages, 4 figures
Journal-ref: Phys. Rev. B 78, 165121 (2008)
\\ ( , 74kb)

Title: Dynamics and statistical mechanics of ultra-cold Bose gases using
   c-field techniques
Authors: P. B. Blakie, A. S. Bradley, M. J. Davis, R. J. Ballagh, and C. W.
Categories: cond-mat.stat-mech cond-mat.other physics.atom-ph quant-ph
Comments: 110 pages, 32 figures. Updated to address referee comments. To appear
   in Advances in Physics
\\ ( , 2871kb)
replaced with revised version Mon, 27 Oct 2008 19:41:16 GMT (984kb)

Title: Robustness of Heisenberg-limited interferometry with balanced Fock
Authors: D. Meiser and M. J. Holland
Categories: quant-ph
Comments: 13 pages, 6 figures; high-resolution version can be obtained from
\\ ( , 984kb)
replaced with revised version Mon, 27 Oct 2008 20:27:30 GMT (1055kb)

Title: Raman Coupling of Zeeman Sublevels in an Alkali Bose Condensate
Authors: K. C. Wright, L. S. Leslie, and N. P. Bigelow
Categories: cond-mat.other
Comments: 12 pages, 16 figures--updated references, small changes to captions,
\\ ( , 1055kb)
replaced with revised version Tue, 28 Oct 2008 18:19:39 GMT (51kb)

Title: Extended Thomas-Fermi Density Functional for the Unitary Fermi Gas
Authors: Luca Salasnich and Flavio Toigo
Categories: cond-mat.other cond-mat.supr-con
Comments: 7 pages, 3 figures, 1 table; corrected some typos; to be published in
   Phys. Rev. A
\\ ( , 51kb)
replaced with revised version Tue, 28 Oct 2008 14:47:05 GMT (549kb)

Title: Beyond mean-field dynamics of small Bose-Hubbard systems based on the
   number-conserving phase space approach
Authors: F. Trimborn, D. Witthaut, and H. J. Korsch
Categories: quant-ph
Comments: Significantly enhanced and revised version (20 pages, 20 figures)
\\ ( , 549kb)
replaced with revised version Wed, 29 Oct 2008 16:28:46 GMT (99kb)

Title: Vacancy supersolid of hard-core bosons on the square lattice
Authors: Long Dang, Massimo Boninsegni and Lode Pollet
Categories: cond-mat.stat-mech
Comments: Replaced with published version
Journal-ref: Phys. Rev. B 78, 132512 (2008)
\\ ( , 99kb)
replaced with revised version Wed, 29 Oct 2008 07:13:03 GMT (415kb)

Title: The inherent fluctuations of the pulsed atom laser in F=2 manifold of
   87Rb atoms
Authors: Lin Xia, Fan Yang, Xiaoji Zhou and Xuzong Chen
Categories: physics.atom-ph
Comments: 5 pages, 6 figures
\\ ( , 415kb)
arXiv:0810.4499 (*cross-listing*)
replaced with revised version Wed, 29 Oct 2008 16:44:08 GMT (698kb)

Title: Coupled Mode Equations and Gap Solitons for the 2D Gross-Pitaevsky
   equation with a non-separable periodic potential
Authors: Tom\'a\v{s} Dohnal and Hannes Uecker
Categories: nlin.PS math.AP physics.optics
\\ ( , 698kb)
replaced with revised version Thu, 30 Oct 2008 14:21:38 GMT (43kb)

Title: Radial quadrupole and scissors modes in trapped Fermi gases across the
   BCS phase transition
Authors: Michael Urban
Categories: cond-mat.other
Comments: 6 pages, v2: extended description of the theoretical method
\\ ( , 43kb)
replaced with revised version Wed, 29 Oct 2008 21:36:03 GMT (185kb)

Title: Point processes in arbitrary dimension from fermionic gases, random
   matrix theory, and number theory
Authors: Salvatore Torquato, A. Scardicchio and Chase E Zachary
Categories: cond-mat.stat-mech math-ph math.MP
Comments: 40 pages, 11 figures, 1 table, iopart; corrected mislabeled section
   numbers and minor typographical issues; minor text changes
\\ ( , 185kb)

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
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Received on Mon Nov 10 2008 - 13:55:15 EST

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