# Matt's arXiv selection: week ending 3 November 2006.

From: Matthew Davis <mdavis_at_physics.uq.edu.au>
Date: Mon, 6 Nov 2006 17:43:52 +1000 (EST)

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

A total of 28 new abstracts this week:

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Paper: cond-mat/0610749
Date: Thu, 26 Oct 2006 20:03:27 GMT (218kb)

Title: Dynamical collapse in a degenerate binary fermion mixture using a
hydrodynamic model
Subj-class: Other
Journal-ref: New J. Phys 8 (2006) 258 (1-15)
\\
We use a time-dependent dynamical hydrodynamic model to study a collapse in a
degenerate fermion-fermion mixture (DFFM) of different atoms. Due to a strong
Pauli-blocking repulsion among identical spin-polarized fermions at short
distances there cannot be a collapse for repulsive interspecies fermion-fermion
interaction. However, there can be a collapse for a sufficiently attractive
interspecies fermion-fermion interaction in a DFFM of different atoms. Using a
variational analysis and numerical solution of the hydrodynamic model we study
different aspects of collapse in such a DFFM initiated by a jump in the
interspecies fermion-fermion interaction (scattering length) to a large
negative (attractive) value using a Feshbach resonance. Suggestion for
experiments of collapse in a DFFM of distinct atoms is made.
\\ ( http://arXiv.org/abs/cond-mat/0610749 , 218kb)
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Paper: cond-mat/0610766
Date: Fri, 27 Oct 2006 11:25:02 GMT (130kb)

Title: Cold Collision Frequency Shift in Two-Dimensional Atomic Hydrogen
Authors: J. Ahokas, J. Jarvinen, and S. Vasiliev
Subj-class: Other
\\
We report a measurement of the cold collision frequency shift in atomic
hydrogen gas adsorbed on the surface of superfluid 4He at T<=90 mK. Using
two-photon electron and nuclear magnetic resonance in 4.6 T field we separate
the resonance line shifts due to the dipolar and exchange interactions, both
proportional to surface density sigma. We find the clock shift Delta v_c =
-1.0(1)x10^-7 Hz cm^-2 x sigma, which is about 100 times smaller than the value
predicted by the mean field theory and known scattering lengths in the 3D case.
\\ ( http://arXiv.org/abs/cond-mat/0610766 , 130kb)
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Paper: cond-mat/0610767
Date: Fri, 27 Oct 2006 14:42:46 GMT (910kb)

Title: Universality in nonadiabatic behaviour of classical actions in nonlinear
models with separatrix crossings
Authors: A.P. Itin, S. Watanabe
Subj-class: Other
\\
We discuss dynamics of approximate adiabatic invariants in several nonlinear
models being related to physics of Bose-Einstein condensates (BEC). We show
that nonadiabatic dynamics in Feschbach resonance passage, nonlinear
Landau-Zener (NLZ) tunnelling, and BEC tunnelling oscillations in a double-well
can be considered within a unifying approach based on the theory of separatrix
crossings. The problems were considered previously within nonlinear two-state
models, and there are regimes of motion that was not discussed so far in the
context of nonadiabatic behaviour, that is when initial populations of either
mode of a two-mode system are not zero or very small. Here we consider a
two-mode model for coupled atom-molecular BEC, and a two-mode model for two
coupled (atomic) BECs as examples. The former model is able to describe process
of Feschbach resonance passage, while the latter is similar to NLZ model.
Self-trapping phenomenon and the associated \emph{geometric} jump in action can
population at adiabatic Feschbach resonance crossing. However, the most
complicated issue is \emph{dynamical} jumps in action at separatrix crossings
which were investigated previously in some problems of classical mechanics,
plasma physics and hydrodynamics, but have not got adequate treatment in
BEC-related models yet. We derive explicit formulas for the change in the
action in several models using a general method of classical adiabatic theory.
Extensive numerical calculations support the general theory and demonstrate its
universal character. We also discovered a qualitatively new nonlinear
phenomenon in a NLZ model which we propose to call {\em separated adiabatic
tunnelling}.
\\ ( http://arXiv.org/abs/cond-mat/0610767 , 910kb)
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Paper: cond-mat/0610773
Date: Fri, 27 Oct 2006 14:00:42 GMT (547kb)

Title: Dynamical properties of ultra-cold bosons in an optical lattice
Authors: S.D. Huber, E. Altman, H.P. B\"uchler, and G. Blatter
Subj-class: Other
\\
We study the excitation spectrum of strongly correlated lattice bosons for
the Mott-insulating phase and for the superfluid phase close to localization.
Within a Schwinger-boson mean-field approach we find two gapped modes in the
Mott insulator and the combination of a sound mode (Goldstone) and a gapped
(Higgs) mode in the superfluid. To make our findings comparable with
experimental results, we calculate the dynamic structure factor as well as the
linear response to the optical lattice modulation introduced by Stoeferle et
al. [Phys. Rev. Lett. 92, 130403 (2004)]. We find that the puzzling finite
frequency absorption observed in the superfluid phase could be explained via
the excitation of the gapped (Higgs) mode. We check the consistency of our
results with an adapted f-sum-rule and propose an extension of the experimental
technique by Stoeferle et al. to further verify our findings.
\\ ( http://arXiv.org/abs/cond-mat/0610773 , 547kb)
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Paper (*cross-listing*): nucl-th/0610105
Date: Thu, 26 Oct 2006 13:46:12 GMT (32kb)

Title: Universal Properties of the Four-Body System with Large Scattering
Length
Authors: H.-W. Hammer (Bonn U.), L. Platter (Ohio U.)
Comments: 14 pages, 4 ps figures
Report-no: HISKP-TH-06/31
Subj-class: Nuclear Theory; Other
\\
Few-body systems with large scattering length have universal properties that
do not depend on the details of their interactions at short distances. We study
the universal bound state properties of the four-boson system with large
scattering length in an effective quantum mechanics approach. We compute the
four-body binding energies using the Yakubovsky equations for positive and
negative scattering length. Moreover, we study the correlation between three-
and four-body energies and present a generalized Efimov plot for the four-body
system. These results are useful for understanding the cluster structure of
nuclei and for the creation of weakly-bound tetramers with cold atoms close to
a Feshbach resonance.
\\ ( http://arXiv.org/abs/nucl-th/0610105 , 32kb)
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Paper: physics/0610253
Date: Fri, 27 Oct 2006 12:02:14 GMT (233kb)

Title: All-optical atomic magnetometers based on nonlinear magneto-optical
rotation with amplitude modulated light
Authors: S. Pustelny, A. Wojciechowski, M. Kotyrba, K. Sycza, J. Zachorowski,
W. Gawlik, A. Cingoz, N. Leefer, J. M. Higbie, E. Corsinib, M. P. Ledbetter,
S. M. Rochester, A. O. Sushkov, and D. Budker
Comments: 8 pages, 6 figures, Submitted to Proc. of SPIE, Proceedings of XIVth
International School on Quantum Electronics, Sunny Beach, Bulgaria 2006
Subj-class: Atomic Physics; Optics
\\
We demonstrate a magnetometric technique based on nonlinear magneto-optical
rotation using amplitude modulated light. The magnetometers can be operated in
either open-loop (typical nonlinear magneto-optical rotation with
amplitude-modulated light) or closed-loop (self-oscillating) modes. The latter
mode is particularly well suited for conditions where the magnetic field is
changing by large amounts over a relatively short timescale.
\\ ( http://arXiv.org/abs/physics/0610253 , 233kb)
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Paper: cond-mat/0610797
Date: Sat, 28 Oct 2006 18:49:26 GMT (50kb)

Title: Theory of Critical Temperature Adiabatic Change for Ideal Gas
Bose-Einstein Condensation in Optical Lattices
Subj-class: Other; Statistical Mechanics
\\
We present a scheme of analytical calculations determining the critical
temperature and the number of condensed atoms of ideal gas Bose-Einstein
condensation in external potentials with 1D, 2D or 3D periodicity. In
particular we show that the width of the lowest energy band appears as the main
parameter determining the critical temperature of condensation. Is obtained a
very simple, proportional to 1/3 degree, regularity for this dependence. The
fundamental role of tunneling in physics of condensate establishment is
underscored.
\\ ( http://arXiv.org/abs/cond-mat/0610797 , 50kb)
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Paper: cond-mat/0610798
Date: Sat, 28 Oct 2006 19:00:47 GMT (278kb)

Title: Large-N expansion for unitary superfluid Fermi gases
Authors: M. Y. Veillette, D. E. Sheehy, and L. Radzihovsky
Subj-class: Other
\\
We analyze strongly interacting Fermi gases in the unitary regime by
considering the generalization to an arbitrary number N of spin-1/2 fermion
flavors with Sp(2N) symmetry. For N=\infty this problem is exactly solved by
the BCS-BEC mean-field theory, with corrections small in the parameter 1/N. The
large-N expansion provides a systematic way to determine corrections to
mean-field predictions, allowing the calculation of a variety of thermodynamic
quantities at (and in the proximity to) unitarity, including the energy, the
pairing gap, and upper-critical polarization (in the case of a polarized gas)
for the normal to superfluid instability. For the physical case of N=1, among
other quantities, we predict in the unitarity regime, the energy of the gas to
be \xi=0.28 times that for the non-interacting gas and the pairing gap to be
0.52 times the Fermi energy.
\\ ( http://arXiv.org/abs/cond-mat/0610798 , 278kb)
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Paper: cond-mat/0610804
Date: Sun, 29 Oct 2006 08:26:12 GMT (34kb)

Title: Intensity correlations and mesoscopic fluctuations of diffusing photons
in cold atoms
Authors: O. Assaf and E. Akkermans
Subj-class: Mesoscopic Systems and Quantum Hall Effect
\\
We study the angular correlation function of speckle patterns that result
from multiple scattering of photons by cold atomic clouds. We show that this
correlation function becomes larger than the value given by Rayleigh law for
classical scatterers. These large intensity fluctuations constitute a new
mesoscopic interference effect specific to atom-photon interactions, that could
not be observed in other systems such as weakly disordered metals. We provide a
complete description of this behavior and expressions that allow for a
quantitative comparison with experiments.
\\ ( http://arXiv.org/abs/cond-mat/0610804 , 34kb)
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Paper: cond-mat/0610830
Date: Mon, 30 Oct 2006 12:19:19 GMT (16kb)

Title: Superfluidity of a Bose gas in the presence of a random potential
Authors: M. Ogren, G. M. Kavoulakis (LTH, Lund)
Comments: 4 pages, RevTex, 3 figures
Subj-class: Other
\\
We examine bosonic atoms that are confined in a toroidal,
quasi-one-dimensional trap, subjected to a random potential. The resulting
inhomogeneous atomic density is smoothened for sufficiently strong, repulsive
interatomic interactions. The gas supports persistent currents, which become
more fragile due to the disorder. Strong disorder requires correspondingly
strong interactions in order for the currents to be (meta)stable.
\\ ( http://arXiv.org/abs/cond-mat/0610830 , 16kb)
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Paper: cond-mat/0610844
Date: Mon, 30 Oct 2006 20:30:41 GMT (87kb)

Title: A Cold Atomic Fermi Gas with a Spatially Modulated Interaction
Authors: Hao Fu, Alberto G. Rojo
Subj-class: Superconductivity; Other
\\
We study an ultra-cold atomic Fermi Gas with the atom-atom interaction
modulated periodically in space. A novel ground state with cooper pairs
occupying non-zero center of mass momenta is found. Such a state is closely
related to the state proposed by Fulde, Ferrell, Larkin, and Ovchinnikov(FFLO).
The resultant single particle excitations with momenta along the direction of
the modulation shows multiple-gap structures. Such a system can be realized in
experiment with a spatially modulated Feshbach resonance. Experimental
signatures of such a state are discussed.
\\ ( http://arXiv.org/abs/cond-mat/0610844 , 46kb)
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Paper: cond-mat/0610848
Date: Mon, 30 Oct 2006 18:47:34 GMT (63kb)

Title: Renormalized mean-field theory for a two-component Fermi gas with s-wave
interactions
Authors: Javier von Stecher, Chris H. Greene
Comments: 11 pages, 9 figures, 2 tables
Subj-class: Superconductivity
\\
A method is introduced to renormalize the zero-range interaction for use in
mean-field and many-body theory, starting from two-body calculations. The
density-renormalized delta-function interaction is then applied using
mean-field theory to a two-component fermion gas, and compared with diffusion
Monte Carlo simulations and conventional mean-field calculations. In the
unitarity limit, the equation of state exhibits the expected behavior
$\mu\propto\rho^{2/3}$, with a parameter $\beta= -0.492$, which is consistent
with recent experiments \cite{partridge2006pap, bourdel2004esb, kinast2005hcs,
Stewart06}.
\\ ( http://arXiv.org/abs/cond-mat/0610848 , 63kb)
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Paper: quant-ph/0610244
Date: Mon, 30 Oct 2006 07:28:01 GMT (519kb)

Title: Emergent quantum phases in a heteronuclear molecular Bose--Einstein
condensate model
Authors: Melissa Duncan, Angela Foerster, Jon Links, Eduardo Mattei, Norman
Oelkers, Arlei Prestes Tonel
\\
We study a three-mode Hamiltonian modelling a heteronuclear molecular
Bose--Einstein condensate. Two modes are associated with two distinguishable
atomic constituents, which can combine to form a molecule represented by the
third mode. Beginning with a semi-classical analogue of the model, we conduct
an analysis to determine the phase space fixed points of the system.
Bifurcations of the fixed points naturally separate the coupling parameter
space into different regions. Two distinct scenarios are found, dependent on
whether the imbalance between the number operators for the atomic modes is zero
or non-zero. This result suggests the ground-state properties of the model
exhibit an unusual sensitivity on the atomic imbalance. We then test this
finding for the quantum mechanical model. Specifically we use Bethe ansatz
methods, ground-state expectation values, the character of the quantum
dynamics, and ground-state wavefunction overlaps to clarify the nature of the
ground-state phases. The character of the transition is smoothed due to quantum
fluctuations, but we may nonetheless identify the emergence of a quantum phase
boundary in the limit of zero atomic imbalance.
\\ ( http://arXiv.org/abs/quant-ph/0610244 , 519kb)
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Paper: quant-ph/0610251
Date: Mon, 30 Oct 2006 15:15:36 GMT (3kb)

Title: Reply to Comment on 'Spin Decoherence in Superconducting Atom Chips'
Authors: Bo-Sture K. Skagerstam, Ulrich Hohenester, Asier Eiguren, and Per
Kristian Rekdal
\\
This is a reply to the Comment on 'Spin Decoherence in Superconducting Atom
Chips' [arXiv:quant-ph/0610095 (2006)].
\\ ( http://arXiv.org/abs/quant-ph/0610251 , 3kb)
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Paper: physics/0610261
Date: Sat, 28 Oct 2006 12:17:41 GMT (29kb)

Title: Low-energy three-body dynamics in binary quantum gases
Authors: O. I. Kartavtsev, A. V. Malykh
Subj-class: Atomic Physics
\\
The universal three-body dynamics in ultra-cold binary Fermi and Fermi-Bose
mixtures is studied. Two identical fermions of the mass $m$ and a particle of
the mass $m_1$ with the zero-range two-body interaction in the states of the
total angular momentum L=1 are considered. Using the boundary condition model
for the s-wave interaction of different particles, both eigenvalue and
scattering problems are treated by solving hyper-radial equations, whose terms
are derived analytically. The dependencies of the three-body binding energies
on the mass ratio $m/m_1$ for the positive two-body scattering length are
calculated; it is shown that the ground and excited states arise at $m/m_1 \ge \lambda_1 \approx 8.17260$ and $m/m_1 \ge \lambda_2 \approx 12.91743$,
respectively. For $m/m_1 \alt \lambda_1$ and $m/m_1 \alt \lambda_2$, the
relevant bound states turn to narrow resonances, whose positions and widths are
calculated. The 2 + 1 elastic scattering and the three-body recombination near
the three-body threshold are studied and it is shown that a two-hump structure
in the mass-ratio dependencies of the cross sections is connected with arising
of the bound states.
\\ ( http://arXiv.org/abs/physics/0610261 , 29kb)
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Paper: cond-mat/0610862
Date: Tue, 31 Oct 2006 07:57:30 GMT (546kb)

Title: Topological defect formation in quenched ferromagnetic Bose-Einstein
condensates
Authors: Hiroki Saito, Yuki Kawaguchi, and Masahito Ueda
Subj-class: Other
\\
We study the dynamics of the quantum phase transition of a ferromagnetic
spin-1 Bose-Einstein condensate from the polar phase to the broken-axisymmetry
phase by changing magnetic field, and find the spontaneous formation of spinor
domain walls followed by the creation of polar-core spin vortices. We also find
that the spin textures depend very sensitively on the initial noise
distribution, and that an anisotropic and colored initial noise is needed to
reproduce the Berkeley experiment [Sadler et al., Nature 443, 312 (2006)]. The
dynamics of vortex nucleation and the number of created vortices depend also on
the manner in which the magnetic field is changed. We point out an analogy
between the formation of spin vortices from domain walls in a spinor BEC and
that of vortex-antivortex pairs from dark solitons in a scalar BEC.
\\ ( http://arXiv.org/abs/cond-mat/0610862 , 546kb)
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Paper: cond-mat/0610881
Date: Tue, 31 Oct 2006 13:59:21 GMT (186kb)

Title: Dark solitons in external potentials
Authors: Dmitry E. Pelinovsky and Panayotis G. Kevrekidis
Subj-class: Other
\\
We consider the persistence and stability of dark solitons in the
Gross-Pitaevskii (GP) equation with a small decaying potential. We show that
families of black solitons with zero speed originate from extremal points of an
appropriately defined effective potential and persist for sufficiently small
strength of the potential. We prove that families at the maximum points are
generally unstable with exactly one real positive eigenvalue, while families at
the minimum points are generally unstable with exactly two complex-conjugated
eigenvalues with positive real part. This mechanism of destabilization of the
black soliton is confirmed in numerical approximations of eigenvalues of the
linearized GP equation and full numerical simulations of the nonlinear GP
equation with cubic nonlinearity. We illustrate the monotonic instability
associated with the real eigenvalues and the oscillatory instability associated
with the complex eigenvalues and compare the numerical results of evolution of
a dark soliton with the predictions of Newton's particle law for its position.
\\ ( http://arXiv.org/abs/cond-mat/0610881 , 186kb)
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Paper: cond-mat/0611010
Date: Wed, 1 Nov 2006 09:53:06 GMT (15kb)

Title: Mixtures of fermionic atoms in an optical lattice
Authors: K. Ziegler
Subj-class: Disordered Systems and Neural Networks; Statistical Mechanics
\\
A mixture of light and heavy spin-polarized fermionic atoms in an optical
lattice is considered. Tunneling of the heavy atoms is neglected such that they
are only subject to thermal fluctuations. This results in a complex interplay
between light and heavy atoms caused by quantum tunneling of the light atoms.
The distribution of the heavy atoms is studied. It can be described by an
Ising-like distribution with a first-order transition from homogeneous to
staggered order. The latter is caused by an effective nonlocal interaction due
to quantum tunneling of the light atoms. A second-order transition is also
possible between an ordered and a disordered phase of the heavy atoms.
\\ ( http://arXiv.org/abs/cond-mat/0611010 , 15kb)
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Paper: cond-mat/0611017
Date: Wed, 1 Nov 2006 16:18:19 GMT (51kb)

Title: Quantum quenches in a spinor condensate
Authors: Austen Lamacraft
Subj-class: Statistical Mechanics
\\
We discuss the ordering of a spin-1 condensate when quenched from its
paramagnetic phase to its ferromagnetic phase by reducing magnetic field. We
first elucidate the nature of the equilibrium quantum phase transition, which
has a multicritical point when the magnetization in the direction of the field
vanishes. Quenching through this transition reveals XY ordering either at a
specific wavevector, or the light-cone' correlations familiar from
relativistic theories, depending on the endpoint of the quench. The creation of
vortices through growth of the magnetization fluctuations is also discussed.
The long time dynamics again depends on the endpoint, conserving the order
parameter in zero field, but not at finite field, with differing exponents for
the coarsening of magnetic order. The results are discussed in the light of a
recent experiment by Sadler et al.
\\ ( http://arXiv.org/abs/cond-mat/0611017 , 51kb)
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Paper: cond-mat/0611022
Date: Wed, 1 Nov 2006 20:56:55 GMT (427kb)

Title: Resonantly-paired fermionic superfluids
Comments: 71 pgs, 28 eps figures
Subj-class: Superconductivity
\\
We present a theory of a degenerate atomic Fermi gas, interacting through a
narrow Feshbach resonance, whose position and therefore strength can be tuned
experimentally, as demonstrated recently in ultracold trapped atomic gases. The
distinguishing feature of the theory is that its accuracy is controlled by a
dimensionless parameter proportional to the ratio of the width of the resonance
to Fermi energy. The theory is therefore quantitatively accurate for a narrow
Feshbach resonance. In the case of a narrow s-wave resonance, our analysis
leads to a quantitative description of the crossover between a weakly-paired
BCS superconductor of overlapping Cooper pairs and a strongly-paired molecular
Bose-Einstein condensate of diatomic molecules. In the case of pairing via a
p-wave resonance, that we show is always narrow for a sufficiently low density,
we predict a detuning-temperature phase diagram, that in the course of a
BCS-BEC crossover can exhibit a host of thermodynamically-distinct phases
separated by quantum and classical phase transitions. For an intermediate
strength of the dipolar anisotropy, the system exhibits a p_x + i p_y paired
superfluidity that undergoes a topological phase transition between a
weakly-coupled gapless ground state at large positive detuning and a
strongly-paired fully-gapped molecular superfluid for a negative detuning. In
two dimensions the former state is characterized by a Pfaffian ground state
exhibiting topological order and non-Abelian vortex excitations familiar from
fractional quantum Hall systems.
\\ ( http://arXiv.org/abs/cond-mat/0611022 , 427kb)
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Paper: quant-ph/0611005
Date: Tue, 31 Oct 2006 23:21:06 GMT (500kb)

Title: Quantum correlation in the photoassociation of a heteronuclear molecular
Bose-Einstein Condensate
Authors: Lu Zhou, Weiping Zhang, Hong Y. Ling, Han Pu
\\
We study a atomic-molecular model for interspecies photoassociation. A
general Hamiltonian which takes into account the s-wave scattering interactions
are considered. By approximating the quantum Hamiltonian by a classical
Hamiltonian, the fixed points of the system are found. The stability analysis
is performed and we found that the population imbalance between the two atomic
species will play an important role in the modulational instability of the
system. It is found that effecient photoassociation could be achieved in wider
experimental parameter region with population imbalance. The dynamics of the
system is predicted with mean-field theory as well as with quantum solution.
The difference between them are found and analyzed. In addition, we give a
brief discussion on the role of the quantum statistical properties of the
initial atomic condensate state on the dynamics of the system. The time
evolution of the correlation between atoms of different species are calculated
with different initial states and we found that the two species can be kept
anti-correlated under appropriate conditions. We also numerically show that
quantum statistical properties of the matter wave field changes due to the
nonlinear interaction.
\\ ( http://arXiv.org/abs/quant-ph/0611005 , 500kb)
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Paper: physics/0611003
Date: Wed, 1 Nov 2006 01:04:59 GMT (109kb)

Title: Probing Ultracold Collisional Dynamics with Frequency-Chirped Pulses
Authors: M.J. Wright, J.A. Pechkis, J.L. Carini, and P.L. Gould
Subj-class: Atomic Physics
\\
We report on the dynamics of ultracold collisions induced by near-resonant
frequency-chirped light. A series of identical chirped pulses, separated by a
variable delay, is applied to an ultracold sample of 85Rb, and the rate of
inelastic trap-loss collisions is measured. For small detunings of the chirped
light below the atomic resonance, we observe that the rate of collisions
induced by a given pulse can be increased by the presence of an earlier pulse.
We attribute this to the enhancement of short-range collisional flux by the
long-range excitation of atom pairs to an attractive molecular potential. For
larger detunings and short delays, we find that a leading pulse can suppress
the rate of collisions caused by a following pulse. This is due to a depletion
of short-range atom pairs by the earlier pulse. Comparison of our data to
classical Monte-Carlo simulations of the collisions yields reasonable
agreement.
\\ ( http://arXiv.org/abs/physics/0611003 , 109kb)
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Paper: cond-mat/0611028
Date: Wed, 1 Nov 2006 19:48:32 GMT (166kb)

Title: Modification of scattering lengths via magnetic dipole-dipole
interactions
Authors: I.E. Mazets and G. Kurizki
Comments: revtex, 4 pages, 3 figures
Subj-class: Statistical Mechanics; Atomic Physics
\\
We propose a new mechanism for tuning an atomic s-wave scattering length. The
effect is caused by virtual transitions between different Zeeman sublevels via
magnetic dipole-dipole interactions. These transitions give rise to an
effective potential, which, in contrast to standard magnetic interactions, has
an isotropic component and thus affects s-wave collisions. Our numerical
analysis shows that for chromium-50 the scattering length can be modified up to
15 %.
\\ ( http://arXiv.org/abs/cond-mat/0611028 , 166kb)
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Paper: cond-mat/0611043
Date: Thu, 2 Nov 2006 07:40:48 GMT (111kb)

Title: Bose-Einstein condensates and quantum non-locality
Authors: Franck Lalo\"{e} (LKB - Lhomond)
Comments: contribution to the workshop "Beyond que quantum", at the Lorentz
Institute (Leiden, Netherlands) in may 2006
Proxy: ccsd hal-00110808
Subj-class: Other
\\
The EPR argument points to the existence of additional variables that are
necessary to complete standard quantum theory. It was dismissed by Bohr because
it attributes physical reality to isolated microscopic systems, independently
of the macroscopic measurement apparatus. Here, we transpose the EPR argument
to macroscopic systems, assuming that they are in spatially extended Fock spin
states and subject to spin measurements in remote regions of space. Bohr's
refutation of the EPR argument does not seem to apply in this case, since the
difference of scale between the microscopic measured system and the macroscopic
measuring apparatus can no longer be invoked.
\\ ( http://arXiv.org/abs/cond-mat/0611043 , 111kb)
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Paper: cond-mat/0611047
Date: Thu, 2 Nov 2006 09:32:27 GMT (33kb)

Title: Collisional decay of 87Rb Feshbach molecules at 1005.8 G
Authors: N. Syassen, T. Volz, S. Teichmann, S. D\"urr, G. Rempe
Subj-class: Statistical Mechanics
\\
We present measurements of the loss-rate coefficients K_am and K_mm caused by
inelastic atom-molecule and molecule-molecule collisions. A thermal cloud of
atomic 87Rb is prepared in an optical dipole trap. A magnetic field is ramped
across the Feshbach resonance at 1007.4 G. This associates atom pairs to
molecules. A measurement of the molecule loss at 1005.8 G yields K_am=2 10^-10
cm^3/s. Additionally, the atoms can be removed with blast light. In this case,
the measured molecule loss yields K_mm=3 10^-10 cm^3/s.
\\ ( http://arXiv.org/abs/cond-mat/0611047 , 33kb)
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Paper: cond-mat/0611054
Date: Thu, 2 Nov 2006 18:12:27 GMT (439kb)

Title: Formation of molecules and entangled atomic pairs from atomic BEC due to
Feshbach resonance
Authors: Vladimir A. Yurovsky (Tel Aviv University)
Subj-class: Soft Condensed Matter
\\
Bose-Einstein condensate (BEC) is considered under conditions of Feshbach
resonance in two-atom collisions due to a coupling of atomic pair and resonant
molecular states. The association of condensate atoms can form a molecular BEC,
and the molecules can dissociate to pairs of entangled atoms in two-mode
squeezed states. Both entanglement and squeezing can be applied to quantum
measurements and information processing.
The processes in the atom-molecule quantum gas are analyzed using two
theoretical approaches. The mean-field one takes into account deactivating
collisions of resonant molecules with other atoms and molecules, neglecting
quantum fluctuations. This method allows analysis of inhomogeneous systems,
such as expanding BEC. The non-mean-field approach -- the parametric
approximation -- takes into account both deactivation and quantum fluctuations.
This method allows determination of optimal conditions for formation of
molecular BEC and describes Bose-enhanced dissociation of molecular BEC, as
well as entanglement and squeezing of the non-condensate atoms.
\\ ( http://arXiv.org/abs/cond-mat/0611054 , 439kb)
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Paper: cond-mat/0611058
Date: Thu, 2 Nov 2006 14:51:55 GMT (53kb)

Title: LOFF and breached pairing with cold atoms
Authors: Amruta Mishra and Hiranmaya Mishra
Comments: 18 pages including 10 figures
Subj-class: Superconductivity
\\
We investigate here the Cooper pairing of fermionic atoms with mismatched
fermi surfaces using a variational construct for the ground state. We determine
the state for different values of the mismatch of chemical potential for weak
as well as strong coupling regimes including the BCS BEC cross over region. We
consider both homogeneous and inhomogeneous Cooper pairing. We also show that
LOFF phase is stable in the weak coupling regime and that the LOFF window is
maximum near the strong coupling regime on the BEC side of the Feshbach
resonance.
\\ ( http://arXiv.org/abs/cond-mat/0611058 , 53kb)
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\\
Paper: cond-mat/0611059
Date: Thu, 2 Nov 2006 14:59:14 GMT (50kb)

Title: Mean-field phase diagram for Bose-Hubbard Hamiltonians with random
hopping
Authors: P. Buonsante, F. Massel, V. Penna, A. Vezzani
Comments: 7 pages, 6 figures. Submitted to Laser Physics
Subj-class: Statistical Mechanics; Other
\\
The zero-temperature phase diagram for ultracold Bosons in a random 1D
potential is obtained through a site-decoupling mean-field scheme performed
over a Bose-Hubbard (BH) Hamiltonian whose hopping term is considered as a
random variable. As for the model with random on-site potential, the presence
of disorder leads to the appearance of a Bose-glass phase. The different phases
-i.e. Mott insulator, superfluid, Bose-glass- are characterized in terms of
condensate fraction and superfluid fraction. Furthermore, the boundary of the
Mott lobes are related to an off-diagonal Anderson model featuring the same
disorder distribution as the original BH Hamiltonian.
\\ ( http://arXiv.org/abs/cond-mat/0611059 , 50kb)
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\\
Paper: physics/0611014
Date: Wed, 1 Nov 2006 21:22:51 GMT (753kb)

Title: Synchronous Optical Pumping of Quantum Revival Beats for Atomic
Magnetometery
Authors: S. J. Seltzer, P. J. Meares, M. V. Romalis
Subj-class: Atomic Physics
\\
We observe quantum beats with periodic revivals due to non-linear spacing of
Zeeman levels in the ground state of potassium atoms and demonstrate their
synchronous optical pumping by double modulation of the pumping light at the
Larmor frequency and the revival frequency. We show that synchronous pumping
increases the degree of spin polarization by a factor of 4. As a practical
example, we explore the application of this double-modulation technique to
atomic magnetometers operating in the geomagnetic field range and find that it
can increase the sensitivity and reduce magnetic field orientation-dependent
measurement errors endemic to alkali-metal magnetometers.
\\ ( http://arXiv.org/abs/physics/0611014 , 753kb)
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The replacements:

------------------------------------------------------------------------------
\\
Paper: cond-mat/0602549
replaced with revised version Fri, 27 Oct 2006 13:39:22 GMT (38kb)

Title: Four-boson scale near a Feshbach resonance
Authors: M. T. Yamashita, Lauro Tomio, A. Delfino and T. Frederico
Subj-class: Soft Condensed Matter; Atomic Physics
Journal-ref: Europhys. Lett. 75, 555 (2006)
\\ ( http://arXiv.org/abs/cond-mat/0602549 , 38kb)
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\\\
Paper: cond-mat/0604063
replaced with revised version Fri, 27 Oct 2006 16:00:21 GMT (347kb)

Title: Disorder contra Mermin-Wagner-Hohenberg effect: From classical spin
systems to ultracold atomic gases
Authors: Jan Wehr (University of Arizona, ICFO), Armand Niederberger (ICFO),
Laurent Sanchez-Palencia (LCFIO), Maciej Lewenstein (ICFO)
Comments: significantly expanded version; 8 pages, 3 figures
Proxy: ccsd ccsd-00022177
Subj-class: Other
\\ ( http://arXiv.org/abs/cond-mat/0604063 , 347kb)
------------------------------------------------------------------------------
\\
Paper: cond-mat/0609052
replaced with revised version Fri, 27 Oct 2006 09:22:11 GMT (22kb)

Title: Quantum Field Theoretical Description of Unstable Behavior of Trapped
Bose-Einstein Condensates with Complex Eigenvalues of Bogoliubov-de Gennes
Equations
Authors: M. Mine, M. Okumura, T. Sunaga, Y. Yamanaka
Subj-class: Other
\\ ( http://arXiv.org/abs/cond-mat/0609052 , 22kb)
------------------------------------------------------------------------------
\\
Paper: cond-mat/0610274
replaced with revised version Thu, 26 Oct 2006 20:33:48 GMT (58kb)

Title: Single-plane-wave Larkin-Ovchinnikov-Fulde-Ferrell state in
BCS--Bose-Einstein condensation crossover
Authors: Yan He, Chih-Chun Chien, Qijin Chen and K. Levin
Comments: 4 pages, 3 figures, some discussions are revised
Subj-class: Strongly Correlated Electrons; Superconductivity
\\ ( http://arXiv.org/abs/cond-mat/0610274 , 58kb)
------------------------------------------------------------------------------
\\
Paper: cond-mat/0503264
replaced with revised version Mon, 30 Oct 2006 04:36:27 GMT (73kb)

Title: Finite Temperature Excitations of a trapped Bose gas by Feynman-Kac path
integral approach
Authors: S. Datta
Subj-class: Other
\\ ( http://arXiv.org/abs/cond-mat/0503264 , 73kb)
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\\
Paper: cond-mat/0604273
replaced with revised version Mon, 30 Oct 2006 15:10:43 GMT (267kb)

Title: Topological constraints on magnetostatic traps
Authors: R. Gerritsma and R. J. C. Spreeuw
Subj-class: Other
Journal-ref: Phys. Rev. A 74, 043405 (2006)
\\ ( http://arXiv.org/abs/cond-mat/0604273 , 267kb)
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\\
Paper: cond-mat/0605056
replaced with revised version Tue, 31 Oct 2006 09:23:18 GMT (758kb)

Title: Dressed molecules in an optical lattice
Authors: K. B. Gubbels, D. B. M. Dickerscheid, and H. T. C. Stoof
Subj-class: Statistical Mechanics
Journal-ref: New Journal of Physics 8, 151 (2006)
\\ ( http://arXiv.org/abs/cond-mat/0605056 , 758kb)
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\\
Paper: cond-mat/0606757
replaced with revised version Tue, 31 Oct 2006 11:17:47 GMT (114kb)

Title: Control of the interaction in a Fermi-Bose mixture
Authors: M. Zaccanti, C. D'Errico, F. Ferlaino, G.Roati, M. Inguscio, G.
Modugno
Subj-class: Other
Journal-ref: PRA 74, 041605(R) (2006)
\\ ( http://arXiv.org/abs/cond-mat/0606757 , 114kb)
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\\
Paper: cond-mat/0609036
replaced with revised version Tue, 31 Oct 2006 05:58:20 GMT (148kb)

Title: Screening effect and delocalization of interacting Bose-Einstein
condensates in random potentials
Authors: Laurent Sanchez-Palencia (LCFIO)
Comments: To appear in Phs. Rev. A; minor changes
Proxy: ccsd ccsd-00090760
Subj-class: Other
\\ ( http://arXiv.org/abs/cond-mat/0609036 , 148kb)
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\\
Paper: cond-mat/0610844
replaced with revised version Tue, 31 Oct 2006 02:55:33 GMT (47kb)

Title: A Cold Atomic Fermi Gas with a Spatially Modulated Interaction
Authors: Hao Fu, Alberto G. Rojo
Comments: 11 pages, 3 figures, replaced with eps figures
Subj-class: Superconductivity; Other
\\ ( http://arXiv.org/abs/cond-mat/0610844 , 47kb)
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\\
Paper: quant-ph/0609077
replaced with revised version Tue, 31 Oct 2006 17:31:43 GMT (37kb)

Title: An investigation into why macroscopic systems behave classically
Authors: David W. Hallwood, Keith Burnett, Jacob Dunningham
Comments: 23 preprint pages, 12 figures
\\ ( http://arXiv.org/abs/quant-ph/0609077 , 37kb)
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\\
Paper: cond-mat/0610703
replaced with revised version Wed, 1 Nov 2006 17:39:48 GMT (185kb)

Title: Scattering of two-dimensional solitons in dipolar Bose-Einstein
condensates
Authors: R. Nath, P. Pedri and L. Santos
Comments: 4 pages, 5 eps figures, minor changes
Subj-class: Other
\\ ( http://arXiv.org/abs/cond-mat/0610703 , 185kb)
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\\
Paper: cond-mat/0610536
replaced with revised version Thu, 2 Nov 2006 12:09:20 GMT (22kb)

Title: Bose-Einstein condensation of magnons in ferromagnets with easy-plane
anisotropy and in antiferromagnets with weakly coupled ferromagnetic plains
or chains
Authors: A. V. Syromyatnikov
Comments: 5 pages, 1 figure, submitted to PRB, some misprints have been
corrected
Subj-class: Strongly Correlated Electrons
\\ ( http://arXiv.org/abs/cond-mat/0610536 , 22kb)
------------------------------------------------------------------------------

Till next week,
Matt.

--
=========================================================================
Dr M. J. Davis,               Senior Lecturer in Physics
School of Physical Sciences,  email: mdavis_at_physics.uq.edu.au
University of Queensland,     ph   : +61 7 334 69824
Brisbane, QLD 4072,           fax  : +61 7 336 51242
Australia.                    http://www.physics.uq.edu.au/people/mdavis/
=========================================================================
Matt's arXiv selection: weekly summary of cold-atom papers from arXiv.org
http://www.physics.uq.edu.au/people/mdavis/matts_arXiv/
=========================================================================
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views of the sender and not the views of the University of Queensland
=========================================================================
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Received on Mon Nov 06 2006 - 17:43:52 EST

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