Matt's arXiv selection, Wednesday 25th October 2006.

From: Matthew Davis <>
Date: Wed, 25 Oct 2006 17:26:57 +1000 (EST)

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

Late again... but today I had my last 3 hours of teaching for 2006. So
from next week I should get back to Mondays for this email...

34 new papers this week.

Home page

The abstracts:

Paper: cond-mat/0610364
Date: Fri, 13 Oct 2006 10:32:46 GMT (401kb)

Title: Dynamical Instabilities in a two-component Bose condensate in a 1d
   optical lattice
Authors: Samantha Hooley and Keith A Benedict
Comments: 14 Pages, 9 figures
Subj-class: Other
   In this paper we carry out a stability analysis of the Bloch states of a
two-component Bose-Einstein condensate confined to a 1d optical lattice. We
consider two concrete systems: a mixture of two hyperfine states of Rubidium-87
and a mixture of Sodium-23 and Rubidium-87. The former is seen to exhibit
similar phenomena to a single component condensate while the latter also
suffers an instability to phase separation at small Bloch wave vectors. It is
shown that sufficiently deep optical lattices can remove this latter
instability, potentially allowing imiscible cold atoms species to be held in
intimate contact and transported within an experimental system.
\\ ( , 401kb)
Paper: cond-mat/0610366
Date: Fri, 13 Oct 2006 11:02:39 GMT (13kb)

Title: Condition for the Existence of Complex Modes in a Trapped Bose--Einstein
   Condensate with a Highly Quantized Vortex
Authors: Eriko Fukuyama, Makoto MIne, Masahiko Okumura, Tomoka Sunaga, Yoshiya
Subj-class: Other
   We consider a trapped Bose--Einstein condensate (BEC) with a highly quantized
vortex. For the BEC with a doubly, triply or quadruply quantized vortex, the
numerical calculations have shown that the Bogoliubov--de Gennes equations,
which describe the fluctuation of the condensate, have complex eigenvalues. In
this paper, we obtain the analytic expression of the condition for the
existence of complex modes, using the method developed by Rossignoli and
Kowalski [R. Rossignoli and A. M. Kowalski, Phys. Rev. A 72, 032101 (2005)] for
the small coupling constant. To derive it, we make the two-mode approximation.
With the derived analytic formula, we can identify the quantum number of the
complex modes for each winding number of the vortex. Our result is consistent
with those obtained by the numerical calculation in the case that the winding
number is two, three or four. We prove that the complex modes always exist when
the condensate has a highly quantized vortex.
\\ ( , 13kb)
Paper: cond-mat/0610367
Date: Fri, 13 Oct 2006 11:20:44 GMT (9kb)

Title: The depletion in Bose Einstein condensates using Quantum Field Theory in
   curved space
Authors: Roberto Balbinot, Serena Fagnocchi, Alessandro Fabbri
Comments: 4 pages, no figure
Subj-class: Other
   Using methods developed in Quantum Field Theory in curved space we can
estimate the effects of the inhomogeneities and of a non vanishing flux on the
depletion of a Bose Einstein condensate within hydrodynamical approximation.
\\ ( , 9kb)
Paper: cond-mat/0610380
Date: Fri, 13 Oct 2006 17:46:33 GMT (17kb)

Title: Ultracold heteronuclear molecules and ferroelectric superfluids
Authors: M. Iskin and C. A. R. Sa de Melo
Comments: 4 pages and 3 figures
Subj-class: Other; Superconductivity
   We analyze the possibility of a ferroelectric transition in heteronuclear
molecules consisting of Bose-Bose, Bose-Fermi or Fermi-Fermi atom pairs. This
transition is characterized by the appearance of a spontaneous electric
polarization below a critical temperature. We discuss the existence of a
ferroelectric Fermi liquid phase for Fermi molecules and the existence of a
ferroelectric superfluid phase for Bose molecules characterized by the
coexistence of ferroelectric and superfluid orders. Lastly, we propose an
experiment to detect ferroelectric correlations through the observation of
coherent dipole radiation pulses during time of flight.
\\ ( , 17kb)
Paper: quant-ph/0610107
Date: Fri, 13 Oct 2006 17:46:14 GMT (610kb)

Title: Non-destructive interferometric characterization of an optical dipole
Authors: Plamen G. Petrov, Daniel Oblak, Carlos L. Garrido Alzar, Niels
   Kjaergaard, and Eugene S. Polzik
Comments: 9 pages, 6 figures, submitted to PRA
   A method for non-destructive characterization of a dipole trapped atomic
sample is presented. It relies on a measurement of the phase-shift imposed by
cold atoms on an optical pulse that propagates through a free space
Mach-Zehnder interferometer. Using this technique we are able to determine,
with very good accuracy, relevant trap parameters such as the atomic sample
temperature, trap oscillation frequencies and loss rates. Another important
feature is that our method is faster than conventional absorption or
fluorescence techniques, allowing the combination of high-dynamical range
measurements and a reduced number of spontaneous emission events per atom.
\\ ( , 610kb)
Paper: physics/0610096
Date: Fri, 13 Oct 2006 01:06:40 GMT (336kb)

Title: Optical atomic coherence at the one-second time scale
Authors: Martin M. Boyd, Tanya Zelevinsky, Andrew D. Ludlow, Seth M. Foreman,
   Sebastian Blatt, Tetsuya Ido, and Jun Ye
Comments: in press (2006)
Subj-class: Atomic Physics; Optics
   Highest resolution laser spectroscopy has generally been limited to single
trapped ion systems due to rapid decoherence which plagues neutral atom
ensembles. Here, precision spectroscopy of ultracold neutral atoms confined in
a trapping potential shows superior optical coherence without any deleterious
effects from motional degrees of freedom, revealing optical resonance
linewidths at the hertz level with an excellent signal to noise ratio. The
resonance quality factor of 2.4 x 10^{14} is the highest ever recovered in any
form of coherent spectroscopy. The spectral resolution permits direct
observation of the breaking of nuclear spin degeneracy for the 1S0 and 3P0
optical clock states of 87Sr under a small magnetic bias field. This optical
NMR-like approach allows an accurate measurement of the differential Lande
g-factor between the two states. The optical atomic coherence demonstrated for
collective excitation of a large number of atoms will have a strong impact on
quantum measurement and precision frequency metrology.
\\ ( , 336kb)
Paper: physics/0610098
Date: Fri, 13 Oct 2006 02:01:43 GMT (145kb)

Title: Dynamic cancellation of ac Stark shift for pulsed EIT/Raman optical
   lattice clocks
Authors: T. Zanon-Willette, A.D. Ludlow, S. Blatt, M.M. Boyd, E. Arimondo,* Jun
Comments: submitted to Physical Review Letters
Subj-class: Atomic Physics; Optics
   We propose a combination of Electromagnetically Induced Transparency
(EIT)/Raman and pulsed spectroscopy techniques to accurately cancel frequency
shifts arising from EIT fields in forbidden optical lattice clock transitions
of alkaline earth atoms. Time-separated laser pulses are designed to trap atoms
in coherent superpositions while eliminating off-resonance ac Stark
contributions at particular laser detunings from the intermediate excited
state. The scheme achieves efficient population transfer up to 60% with
potential inaccuracy $<$ $10^{-17}$. Cancellation of external light shifts
determined by a density matrix approach is confirmed by a complex wave-function
formalism, sufficient at the mHz accuracy, under low field strengths or short
interaction times.
\\ ( , 144kb)
Paper: cond-mat/0610389
Date: Mon, 16 Oct 2006 06:37:23 GMT (198kb)

Title: Ultracold Bose Gases in 1D Random Potentials: From Lifshits Glasses to
   Bose-Einstein Condensates
Authors: Pierre Lugan (LCFIO), David Cl\'{e}ment (LCFIO), Philippe Bouyer
   (LCFIO), Alain Aspect (LCFIO), Maciej Lewenstein (ICFO), Laurent
   Sanchez-Palencia (LCFIO)
Comments: 4 pages; 3 figures; minor reformulations compared to version 1
Proxy: ccsd ccsd-00106356
Subj-class: Other
   We study an ultracold Bose gas in the presence of 1D disorder for repulsive
inter-atomic interactions, ranging from zero to the Thomas-Fermi regime. We
show that for very small interactions, the Bose gas populates a finite number
of localized single particle Lifshits states, while for large interactions, it
forms a delocalized disordered Bose-Einstein condensate. We discuss the phase
diagram and compute the equations of state in various phases.
\\ ( , 198kb)
Paper: cond-mat/0610400
Date: Sun, 15 Oct 2006 14:02:31 GMT (146kb)

Title: Thermodynamics of ideal quantum gas with fractional statistics in D
Authors: Geoffrey G. Potter and Gerhard Muller and Michael Karbach
Comments: 15 pages, 31 figures
Subj-class: Statistical Mechanics; Disordered Systems and Neural Networks
   We present exact and explicit results for the thermodynamic properties
(isochores, isotherms, isobars, response functions, velocity of sound) of a
quantum gas in dimensions D>=1 and with fractional exclusion statistics 0<=g<=1
connecting bosons (g=0) and fermions (g=1). In D=1 the results are equivalent
to those of the Calogero-Sutherland model. Emphasis is given to the crossover
between boson-like and fermion-like features, caused by aspects of the
statistical interaction that mimic long-range attraction and short-range
repulsion. The full isochoric heat capacity and the leading low-T term of the
isobaric expansivity in D=2 are independent of g. The onset of Bose-Einstein
condensation along the isobar occurs at a nonzero transition temperature in all
dimensions. The T-dependence of the velocity of sound is in simple relation to
isochores and isobars. The effects of soft container walls are accounted for
rigorously for the case of a pure power-law potential.
\\ ( , 146kb)
Paper: cond-mat/0610402
Date: Sun, 15 Oct 2006 17:03:41 GMT (92kb)

Title: Entanglement properties and moment distributions of a system of
   hard-core anyons on a ring
Authors: Raoul Santachiara, Franck Stauffer and Daniel Cabra
Comments: 5 pages, 3 eps figures
Subj-class: Strongly Correlated Electrons; Mesoscopic Systems and Quantum Hall
   We study the one-particle von Neumann entropy of a system of N hard-core
anyons on a ring. The entropy is found to have a clear dependence on the
anyonic parameter which characterizes the generalized fractional statistics
described by the anyons. This confirms the entanglement as a valuable measure
to investigate topological properties of quantum states. Furthermore, we
determine analytically the large N asymptotics of the anyonic one-particle
density matrix. The formula presented here generalizes the Lenard formula
obtained for a system of N hard-core bosons. Finally, we present a numerical
analysis which confirms the analytical results and provides additional insight
into the problem under consideration.
\\ ( , 92kb)
Paper: cond-mat/0610411
Date: Mon, 16 Oct 2006 08:34:03 GMT (10kb)

Title: Level Density of a Bose Gas and Extreme Value Statistics
Authors: A. Comtet, P. Leboeuf, Satya N. Majumdar
Comments: 4 pages, no figures
Subj-class: Statistical Mechanics
   We establish a connection between the level density of a gas of
non-interacting bosons and the theory of extreme value statistics. Depending on
the exponent that characterizes the growth of the underlying single-particle
spectrum, we show that at a given excitation energy the limiting distribution
function for the number of excited particles follows the three universal
distribution laws of extreme value statistics, namely Gumbel, Weibull and
Fr\'echet. Implications of this result, as well as general properties of the
level density at different energies, are discussed.
\\ ( , 10kb)
Paper: cond-mat/0610412
Date: Mon, 16 Oct 2006 08:51:38 GMT (7kb)

Title: Bose-Einstein condensation temperature of a gas of weakly dissociated
   diatomic molecules
Authors: L. M. Jensen, H. M\"akel\"a and C. J. Pethick
Comments: 4 pages
Report-no: NORDITA-2006-35
Subj-class: Other; Superconductivity
   We consider the properties of a gas of bosonic diatomic molecules in the
limit when few of the molecules are dissociated. Taking into account the
effects of dissociation and scattering among molecules and atoms, we calculate
the dispersion relation for a molecule, and the thermal depletion of the
condensate. We calculate the dependence of the Bose-Einstein condensation
temperature of a uniform gas on the atom-atom scattering length, and conclude
that, for a broad Feshbach resonance, the condensation temperature increases as
the molecular state becomes less strongly bound, thereby giving rise to a
maximum in the transition temperature in the BEC-BCS crossover. We also argue
on general grounds that, for a gas in a harmonic trap and for a narrow Feshbach
resonance, the condensation temperature will decrease with increasing
scattering length.
\\ ( , 7kb)
Paper: cond-mat/0610414
Date: Mon, 16 Oct 2006 09:00:15 GMT (245kb)

Title: Production of a degenerate Fermi gas of metastable helium-3 atoms
Authors: W. Vassen, T. Jeltes, J.M. McNamara and A.S. Tychkov
Comments: 18 pages, 11 figures; to be published in the Proceedings of the
   International school of physics "Enrico Ferm": Ultracold Fermi gases,
   Varenna, June 20-30 (2006)
Subj-class: Other
   We give an overview of the experiments at the Laser Centre of the Vrije
Universiteit in Amsterdam on ultracold gases of metastable helium-4 and
helium-3 as well as mixtures of both isotopes. We describe our experimental
setup and discuss our experiments on Bose-Einstein condensation of 4He* (more
than 10 million atoms in a BEC) and sympathetic cooling of 3He* towards Fermi
degeneracy (more than 1 million atoms below the Fermi temperature as well as
realization of a degenerate boson-fermion mixture). We also present our results
on Penning Ionization in ~1 mK clouds containing a single isotope (homonuclear
losses) or a mixture of both isotopes (heteronuclear losses).
\\ ( , 245kb)
Paper: cond-mat/0610420
Date: Mon, 16 Oct 2006 11:50:34 GMT (6kb)

Title: Kelvin-wave turbulence generated by vortex reconnections
Authors: Sergey Nazarenko
Comments: To be submitted to JETP Letters
Subj-class: Other; Statistical Mechanics
   Reconnections of quantum vortex filaments create sharp bends which degenerate
into propagating Kelvin waves. These waves cascade their energy down-scale and
their waveaction up-scale via weakly nonlinear interactions, and this is the
main mechanism of turbulence at the scales less than the inter-vortex distance.
In case of an idealised forcing concentrated around a single scale k0, the
turbulence spectrum exponent has a pure direct cascade form -17/5 at scales
k>k0 and a pure inverse cascade form -3 at k<k0. However, forcing produced by
the reconnections contains a broad range of Fourier modes. What scaling should
one expect in this case? In this Letter I obtain an answer to this question
using the differential model for the Kelvin wave turbulence. The main result is
that the direct cascade scaling dominates, i.e. the reconnection forcing is
more or less equivalent to a low-frequency forcing.
\\ ( , 6kb)
Paper: cond-mat/0610435
Date: Mon, 16 Oct 2006 15:10:53 GMT (15kb)

Title: Paired state in spinor bosons: from exact result to mean field approach
Authors: Junpeng Cao, Yuzhu Jiang, Yupeng Wang
Subj-class: Strongly Correlated Electrons
   An exactly solvable model describing the low density limit of the spinor
bosons in a one dimensional optical lattice is proposed. The exact Bethe ansatz
solution shows that the low energy physics of this system is described by a
quantum liquid of spin singlet bound pairs. Motivated by the exact results, a
mean-field approach to the corresponding three-dimensional system is carried
out. Condensation of singlet pairs and coexistence with ordinary Bose-Einstein
condensation are observed.
\\ ( , 15kb)
Paper: cond-mat/0610437
Date: Mon, 16 Oct 2006 17:10:20 GMT (40kb)

Title: Attractive Fermi gases with unequal populations in higly elongated traps
Authors: G. Orso
Comments: 5 pages, 3 figures
Subj-class: Other; Superconductivity
   We investigate two-component attractive Fermi gases with density imbalance in
trapped quasi-1D configurations. The ground state properties are determined
within local density approximation, starting from the exact Bethe-ansatz
equations for the homogeneous case. We predict that the atoms are distributed
according to a two-shell structure with a partially polarized phase in the
center of the trap and either a fully paired or a fully polarized phase in the
wings. The size of the cloud as well as the critical polarization needed to
suppress the fully paired shell, are calculated as a function of the coupling
\\ ( , 40kb)
Paper: quant-ph/0610114
Date: Mon, 16 Oct 2006 02:49:57 GMT (140kb)

Title: Rotation of quantum gases in a two dimensional lattice with a harmonic
Authors: T. Wang, S. Yelin
Comments: 4 pages
   Rotation of gases in a lattice is studied with the Hubbard model. It is found
that the gases do not fly away when the rotation frequency is slightly greater
than the trapping frequency, which is very different from the behavior in
continuum. The Bragg scattering and the coupling between the angular motion and
the radial motion make the above stability possible. In this regime, density
depletion at the center of the trap can be developed for spin polarized
\\ ( , 140kb)
Paper: quant-ph/0610117
Date: Sat, 14 Oct 2006 15:07:17 GMT (36kb)

Title: Is Fault-Tolerant Quantum Computation Really Possible?
Authors: M. I. Dyakonov
Comments: Based on a talk given at the Future Trends in Microelectronics
   workshop, Crete, June 2006. 8 pages, 1 figure
   The so-called "threshold" theorem says that, once the error rate per qubit
per gate is below a certain value, indefinitely long quantum computation
becomes feasible, even if all of the qubits involved are subject to relaxation
processes, and all the manipulations with qubits are not exact. The purpose of
this article, intended for physicists, is to outline the ideas of quantum error
correction and to take a look at the proposed technical instruction for
fault-tolerant quantum computation. It seems that the mathematics behind the
threshold theorem is somewhat detached from the physical reality, and that some
ideal elements are always present in the construction. This raises serious
doubts about the possibility of large scale quantum computations, even as a
matter of principle.
\\ ( , 36kb)
Paper: cond-mat/0610445
Date: Mon, 16 Oct 2006 22:44:06 GMT (466kb)

Title: Quantum Scattering of Distinguishable Bosons using an Ultracold Atom
Authors: Angela S. Mellish, Niels Kjaergaard, Paul S. Julienne, and Andrew C.
Subj-class: Other
   We describe a new implementation of magnetic collider for investigating cold
collisions between ultracold atomic clouds in different spin states, and we use
this to investigate scattering involving both even and odd order partial waves.
Our method relies on the axial assymetry of a double-well magnetic trap to
selectively prepare the spin state in each cloud. We measure the energy
dependence of s, p and d partial wave phase shifts in collisions up to 300
microKelvin between ^{87}Rb atoms in the 5S_{1/2}, F=1, m_F=-1 and 5S_{1/2},
F=2, m_F=1 states.
\\ ( , 466kb)
Paper: cond-mat/0610448
Date: Tue, 17 Oct 2006 10:32:44 GMT (259kb)

Title: FFLO phase in one-dimensional polarized Fermi gases
Authors: Hui Hu, Xia-Ji Liu, and Peter D. Drummond
Comments: 4 pages, 5 figures
Subj-class: Superconductivity; Statistical Mechanics
   Based on the integrable Gaudin model and local density approximation, we
discuss the phase structure of one-dimensional trapped Fermi gases with
imbalanced spin populations for arbitrary attractive interactions. A phase
separation state, with a polarized superfluid core immersed in an unpolarized
superfluid shell, emerges below a critical spin polarization. Above it, a
coexistence of polarized superfluid matter and a fully polarized normal gas is
favored. These two exotic states could be realized experimentally in highly
elongated atomic traps, and diagnosed by measuring the lowest density
compressional mode. We identify the polarized superfluid as having an FFLO
structure, and predict the resulting mode frequency as a function of the spin
\\ ( , 259kb)
Paper: cond-mat/0610476
Date: Tue, 17 Oct 2006 14:42:40 GMT (207kb)

Title: Mean-field phase diagram of cold lattice bosons in disordered potentials
Authors: P. Buonsante, V. Penna, A. Vezzani and P.B. Blakie
Comments: 5 pages, 4 figures
Subj-class: Soft Condensed Matter; Statistical Mechanics
   We show that a site-dependent mean-field approach captures the quantum phases
of the disordered Bose-Hubbard model commonly adopted to describe ultracold
bosons in random optical lattice potentials. The different phases, namely
superfluid, Mott insulator, Bose-glass and -- at finite temperature -- normal
fluid, are characterized by means of the superfluid and condensate fractions,
and compressibility of the system. We point out that both the boundaries of the
Mott lobes and the nature of the phase surrounding them are related to the
spectral features of a purely off-diagonal non-interacting Anderson model. We
compare our results to other works.
\\ ( , 207kb)
Paper: cond-mat/0610485
Date: Tue, 17 Oct 2006 18:56:07 GMT (233kb)

Title: Vortices and phase transitions of interacting bosons in a rotating
   lattice ring
Authors: Qi Zhou
Comments: 4 pages, 3 figures
Subj-class: Other
   We investigate the ground state properties of the repulsive interacting
bosons in an one dimensional rotating lattice ring, and reveal that the
superfluid density of the system and the mass current it can carry in the
rotating coordinate are periodic functions of the velocity of the lattice. In
the weakly interacting limit, the vortices are generated at the critical
velocities, and in the strongly interacting limit, the phase twist of the
bosons induced by the rotating lattice manifests the superfluid density and
drive the system to undergo phase transitions between the superfluid and Mott
\\ ( , 233kb)
Paper: quant-ph/0610135
Date: Tue, 17 Oct 2006 09:59:37 GMT (12kb)

Title: Majorana spin-flip transitions in a magnetic trap
Authors: D.M.Brink and C.V.Sukumar
Comments: 16pages
   Atoms confined in a magnetic trap can escape by making spin-flip Majorana
transitions due to a breakdown of the adiabatic approximation. Several papers
have studied this process for atoms with spin $F = 1/2$ or $F= 1$. The present
paper calculates the escape rate for atoms with spin $F > 1$. This problem has
new features because the perturbation $\Delta T$ which allows atoms to escape
satisfies a selection rule $\Delta F_z = 0, \pm 1, \pm 2$ and multi-step
processes contribute in leading order. When the adiabatic approximation is
satisfied the leading order terms can be summed to yield a simple expression
for the escape rate.
\\ ( , 12kb)
Paper: quant-ph/0610136
Date: Tue, 17 Oct 2006 10:28:32 GMT (380kb)

Title: Optical Nanofibers for Manipulating and Probing Single-Atom Fluorescence
Authors: K. P. Nayak, P. N. Melentiev, M. Morinaga, Fam Le Kien, V. I. Balykin,
   and K. Hakuta
   We demonstrate how optical nanofibers can be used to manipulate and probe
single-atom fluorescence. We show that fluorescence photons from a very small
number of atoms, average atom number of less than 0.1, around the nanofiber can
readily be observed through single-mode optical fiber under resonant laser
irradiation. We show also that optical nanofibers enable us to probe the van
der Waals interaction between atoms and surface with high precision by
observing the fluorescence excitation spectrum.
\\ ( , 380kb)
Paper: quant-ph/0610141
Date: Tue, 17 Oct 2006 16:04:58 GMT (156kb)

Title: High-temperature Bose-Einstein condensation of polaritons: realization
   under the intracavity laser pumping of matter condition
Authors: V. A. Averchenko, A. P. Alodjants, S. M. Arakelian, S. N. Bagayev, E.
   A. Vinogradov, V. S. Egorov, A. I. Stolyarov, I. A. Chekhonin
Comments: 9 pages, PDF only
Journal-ref: Kvantovaya Elektronika (Quantum Elactronics), V.36 (2006)
   A quantum model of Bose-Einstein condensation based on processes involving
polaritons excited in an intracavity absorbing cell with resonance atoms, which
is manifested in the spectral characteristics of the system, is considered. It
is shown that the spectral 'condensation' appears which is directly related to
the degeneracy of a weakly interacting gas of polaritons resulting in
quasi-condensation at room temperature. The possibility of obtaining polariton
condensation as a new phase state by using the confinement of polaritons in an
atomic optical harmonic trap is discussed.
\\ ( , 156kb)
Paper: physics/0610123
Date: Tue, 17 Oct 2006 11:18:51 GMT (52kb)

Title: Dissipative light field as a way to create strongly localized structures
   for atom lithography
Authors: O.N. Prudnikov, A.V. Taichenachev, A.M. Tumaikin, V.I. Yudin
Comments: 4 figures
Subj-class: Atomic Physics
   Generally, the conditions for deep sub-Doppler laser cooling do not match the
conditions for the strong atomic localization that takes a place in deeper
optical potential and, in consequence, leads to larger temperature. Moreover,
for a given detuning in a deep optical potential the secular approximation
which is usually used for quantum description of laser cooling becomes no more
valid. Here we perform an analysis of atomic localization in optical potential
based on a full quantum approach for atomic density matrix. We also show that
the laser cooling in a deep far-off detuned optical potential, created by a
light field with a polarization gradient, can be used as an alternative method
for forming high contrast spatially localized structures of atoms for the
purposes of atom lithography and atomic nanofabrication. Finally, we perform an
analysis of the possible limits for the width and the contrast of localized
atomic structures that can in principle be reached by this type of the light
\\ ( , 52kb)
Paper: cond-mat/0610498
Date: Wed, 18 Oct 2006 07:46:25 GMT (105kb)

Title: Damagnetization cooling of a gas
Authors: M. Fattori, T. Koch, S. Goetz, A. Griesmaier, S. Hensler, J. Stuhler,
   T. Pfau
Comments: 10 pages, 5 figures
Subj-class: Other
Journal-ref: Nature Physics, November 2006
   We demonstrate demagnetization cooling of a gas of ultracold $^{52}$Cr atoms.
Demagnetization is driven by inelastic dipolar collisions which couple the
motional degrees of freedom to the spin degree. By that kinetic energy is
converted into magnetic work with a consequent temperature reduction of the
gas. Optical pumping is used to magnetize the system and drive continuous
demagnetization cooling. Applying this technique, we can increase the phase
space density of our sample by one order of magnitude, with nearly no atom
loss. This method can be in principle extended to every dipolar system and
could be used to achieve quantum degeneracy via optical means.
\\ ( , 105kb)
Paper: cond-mat/0610512
Date: Wed, 18 Oct 2006 14:54:29 GMT (396kb)

Title: Symmetry breaking in small rotating cloud of trapped ultracold Bose
Authors: D. Dagnino, N. Barber\'an, M. Lewenstein, K. Osterloh, and A. Riera
Comments: 4 pages, 2 figures
Subj-class: Mesoscopic Systems and Quantum Hall Effect
   We study the signatures of rotational and phase symmetry breaking in small
rotating clouds of trapped ultracold Bose atoms by looking at rigorously
defined condensate wave function. Rotational symmetry breaking occurs in narrow
frequency windows, where the ground state of the system has degenerated with
respect to the total angular momentum, and it leads to a complex wave function
that exhibits vortices clearly seen as holes in the density, as well as
characteristic vorticity. Phase symmetry (or gauge symmetry) breaking, on the
other hand, is clearly manifested in the interference of two independent
rotating clouds.
\\ ( , 396kb)
Paper: quant-ph/0610149
Date: Wed, 18 Oct 2006 14:07:38 GMT (285kb)

Title: Quantum interference between two single photons emitted by independently
   trapped atoms
Authors: Jerome Beugnon (LCFIO), Matthew Jones (LCFIO), Jos Dingjan (LCFIO),
   Benoit Darqui\'{e} (LCFIO), Gaetan Messin (LCFIO), Antoine Browaeys (LCFIO),
   Philippe Grangier (LCFIO)
Proxy: ccsd ccsd-00107420
Journal-ref: Nature 440 (06/04/2006) 779
   When two indistinguishable single photons are fed into the two input ports of
a beam splitter, the photons will coalesce and leave together from the same
output port. This is a quantum interference effect, which occurs because the
two possible paths where the photons leave in different output ports interfere
destructively. This effect was first observed in parametric downconversion by
Hong, Ou and Mandel, and then with single photons produced one after the other
by the same quantum emitter. With the recent development of quantum
information, a lot of attention has been devoted to this coalescence effect as
a resource for quantum data processing using linear optics techniques. To
ensure the scalability of schemes based on these ideas, it is crucial that
indistinguishable photons are emitted by a collection of synchronized, but
otherwise independent sources. In this paper, we demonstrate the quantum
interference of two single photons emitted by two independently trapped single
atoms, bridging the gap towards the simultaneous emission of many
indistinguishable single photons by different emitters. Our data analysis shows
that the coalescence observed is mostly limited by the wavefront matching of
the light emitted by the two atoms, and to a lesser extent by the motion of
each atom in its own trap.
\\ ( , 285kb)
Paper: quant-ph/0610150
Date: Wed, 18 Oct 2006 15:53:02 GMT (268kb)

Title: Atom in a coherently controlled squeezed vacuum
Authors: Itay Rabinak, Eran Ginossar and Shimon Levit
Comments: 4 pages, 4 figures
   A broadband squeezed vacuum photon field is characterized by a complex
squeezing function. We show that by controlling the wavelength dependence of
its phase it is possible to change the dynamics of the atomic polarization
interacting with the squeezed vacuum. Such a phase modulation effectively
produces a finite range temporal interaction kernel between the two quadratures
of the atomic polarization yielding the change in the decay rates as well as
the appearance of additional oscillation frequencies. We show that decay rates
slower than the spontaneous decay rate can be achieved even for a squeezed bath
in the classic regime. For linear and quadratic phase modulations the power
spectrum of the scattered light exhibits narrowing of the central peak due to
the modified decay rates. For strong phase modulations side lobes appear
symmetrically around the central peak reflecting additional oscillation
\\ ( , 268kb)
Paper: physics/0610131
Date: Tue, 17 Oct 2006 23:40:23 GMT (156kb)

Title: Cold Atomic Collisions: Coherent Control of Penning and Associative
Authors: Carlos A. Arango, Moshe Shapiro, and Paul Brumer
Comments: 4 pages, 2 tables, 2 figures
Subj-class: Chemical Physics; Atomic Physics
   Coherent Control techniques are computationally applied to cold (1mK < T < 1
K) and ultracold (T < 1 microK) Ne*(3s,3P2) + Ar(1S0) collisions. We show that
by using various initial superpositions of the Ne*(3s,3P2) M = {-2,-1,0,1,2}
Zeeman sub-levels it is possible to reduce the Penning Ionization (PI) and
Associative Ionization (AI) cross sections by as much as four orders of
magnitude. It is also possible to drastically change the ratio of these two
processes. The results are based on combining, within the "Rotating Atom
Approximation", empirical and ab-initio ionization-widths.
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Paper: cond-mat/0610532
Date: Thu, 19 Oct 2006 08:57:27 GMT (129kb)

Title: Dynamical Instability in a Trimeric Chain of Interacting Bose-Einstein
Authors: P. Buonsante, R. Franzosi, and V. Penna
Comments: 5 pages, 3 figures
Subj-class: Other
Journal-ref: Phys. Rev Lett. 90 (2003) 050404
DOI: 10.1103/PhysRevLett.90.050404
   We analyze thoroughly the mean-field dynamics of a linear chain of three
coupled Bose-Einstein condensates, where both the tunneling and the
central-well relative depth are adjustable parameters. Owing to its
nonintegrability, entailing a complex dynamics with chaos occurrence, this
system is a paradigm for longer arrays whose simplicity still allows a thorough
analytical study.We identify the set of dynamics fixed points, along with the
associated proper modes, and establish their stability character depending on
the significant parameters. As an example of the remarkable operational value
of our analysis, we point out some macroscopic effects that seem viable to
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Paper: cond-mat/0610536
Date: Thu, 19 Oct 2006 12:38:27 GMT (21kb)

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
Subj-class: Strongly Correlated Electrons
   Bose-Einstein condensation of magnons (BEC) in antiferromagnets (AFs) is
attracted much attention now. In the present paper we discuss BEC in two
classes of magnets that have not been considered before: easy-plane
ferromagnets and AFs containing weakly coupled ferromagnetic plains or chains.
We show that in these magnets the point $H=H_c$ is a quantum critical point
belonging to BEC universality class, where $H$ is the transverse magnetic field
and $H_c$ is its saturation value. Magnetic materials of these types are
promising candidates for experimental investigation of BEC because they have
small saturation fields.
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Paper (*cross-listing*): math-ph/0610034
Date: Mon, 16 Oct 2006 17:31:44 GMT (12kb)

Title: Bose-Einstein Condensation and Spontaneous Symmetry Breaking
Authors: Elliott H. Lieb, Robert Seiringer, Jakob Yngvason
Comments: Contribution to the proceedings of the 21st Max Born Symposium,
   Wroclaw, Poland, June 26--28, 2006
Subj-class: Mathematical Physics; Statistical Mechanics
   After recalling briefly the connection between spontaneous symmetry breaking
and off-diagonal long range order for models of magnets a general proof of
spontaneous breaking of gauge symmetry as a consequence of Bose-Einstein
Condensation is presented. The proof is based on a rigorous validation of
Bogoliubov's $c$-number substitution for the ${\bf k}={\bf 0}$ mode operator
$a_{\bf 0}$.
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Paper: cond-mat/0601500
replaced with revised version Thu, 12 Oct 2006 20:38:44 GMT (18kb)

Title: Thermodynamically activated vortex-dipole formation in a two-dimensional
   Bose-Einstein condensate
Authors: Daniel Schumayer and David A. W. Hutchinson
Comments: 5 pages, 3 figures v2: restructured and minor corrections were made
Subj-class: Statistical Mechanics
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Paper: quant-ph/0601079
replaced with revised version Fri, 13 Oct 2006 01:16:10 GMT (164kb)

Title: Entanglement of indistinguishable particles in condensed matter physics
Authors: Mark R. Dowling, Andrew C. Doherty and Howard M. Wiseman
Comments: 13 pages, 6 figures, comments welcome, published version (minor
   changes, added references)
Journal-ref: Phys. Rev. A, 73, 052323 (2006)
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Paper: physics/0412124
replaced with revised version Fri, 13 Oct 2006 15:27:55 GMT (366kb)

Title: Measurement method for the nuclear anapole moment of laser trapped
   alkali atoms
Authors: E. Gomez (1), S. Aubin (1 and 2), G. D. Sprouse (1), L. A. Orozco (3),
   D. P. DeMille (4) ((1) Dept. of Physics and Astronomy, State University of
   New York at Stony Brook, NY, U.S.A., (2) Dept. of Physics, University of
   Toronto, Ontario, Canada, (3) Dept. of Physics, University of Maryland,
   College Park, MD, U.S.A., (4) Dept. of Physics, Yale University, New Haven,
   CT, U.S.A.)
Comments: 12 pages, 4 figures
Subj-class: Atomic Physics
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Paper: cond-mat/0506293
replaced with revised version Sun, 15 Oct 2006 01:33:34 GMT (57kb)

Title: A new many-body wave function for BCS-BEC crossover in Fermi gases
Authors: Shina Tan and K. Levin
Comments: 5 pages, 2 color figures
Subj-class: Statistical Mechanics
Journal-ref: Phys. Rev. A 74, 043606 (2006)
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Paper: cond-mat/0608673
replaced with revised version Sat, 14 Oct 2006 13:10:22 GMT (369kb)

Title: Spin-quadrupole ordering of spin-3/2 ultracold fermionic atoms in
   optical lattices in the one-band Hubbard model
Authors: Hong-Hao Tu, Guang-Ming Zhang, Lu Yu
Comments: 12 pages, 4 figures
Subj-class: Strongly Correlated Electrons
Journal-ref: Phys. Rev. B 74, 037641 (2006)
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Paper (*cross-listing*): math-ph/0510006
replaced with revised version Mon, 16 Oct 2006 17:51:59 GMT (31kb)

Title: Bosons in Disc-Shaped Traps: From 3D to 2D
Authors: K. Schnee, J. Yngvason
Comments: Corrected version. To be published in Communications in Mathematical
Subj-class: Mathematical Physics; Statistical Mechanics
\\ ( , 31kb)
Paper: physics/0604008
replaced with revised version Mon, 16 Oct 2006 08:20:22 GMT (359kb)

Title: Anomalous translational velocity of vortex ring with finite-amplitude
   Kelvin waves
Authors: C.F. Barenghi, R. H\"anninen, M. Tsubota
Comments: 6 pages, 5 figures, v2: minor changes, v3: typos corrected
Subj-class: Fluid Dynamics; Soft Condensed Matter
Journal-ref: Phys. Rev. E 74, 046303 (2006)
DOI: 10.1103/PhysRevE.74.046303
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Paper: cond-mat/0601650
replaced with revised version Mon, 16 Oct 2006 21:15:28 GMT (33kb)

Title: Dynamics of the Bose-Hubbard model: transition from Mott insulator to
Authors: Fernando M. Cucchietti, Bogdan Damski, Jacek Dziarmaga, and Wojciech
   H. Zurek
Comments: 7+ pages, the Bogolubov section is completely rewritten
Report-no: LAUR-06-0477
Subj-class: Other
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Paper: cond-mat/0604086
replaced with revised version Tue, 17 Oct 2006 17:39:45 GMT (331kb)

Title: Bright Matter-Wave Soliton Collisions in a Harmonic Trap: Regular and
   Chaotic Dynamics
Authors: A. D. Martin, C. S. Adams and S. A. Gardiner
Comments: 4 pages, 3 figures, content changed in response to referee comments,
   references added
Subj-class: Other
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Paper: cond-mat/0609337
replaced with revised version Wed, 18 Oct 2006 01:35:47 GMT (388kb)

Title: Quantum Entanglement Manifestation of Transition to Nonlinear
   Self-trapping for Bose-Einstein Condensates in a Symmetric Double-Well
Authors: Li-Bin Fu and Jie Liu
Comments: 6 pages, 5 figures
Subj-class: Mesoscopic Systems and Quantum Hall Effect
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Paper: cond-mat/0610345
replaced with revised version Wed, 18 Oct 2006 08:27:14 GMT (38kb)

Title: Collective mode description for a clean Fermi gas with repulsion in
   arbitrary dimensions: interaction of spin excitations and its consequences
Authors: K.B. Efetov, I.L. Aleiner
Comments: A talk given at the conference "Mott's Physics in Nanowires and
   Quantum Dots", Cambridge, UK, 2006; corrected typos
Subj-class: Strongly Correlated Electrons; Disordered Systems and Neural
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Paper: quant-ph/0604165
replaced with revised version Wed, 18 Oct 2006 04:04:08 GMT (113kb)

Title: Entanglement of orbital angular momentum states between an ensemble of
   cold atoms and a photon
Authors: R. Inoue, N. Kanai, T. Yonehara, Y. Miyamoto, M. Koashi and M. Kozuma
Comments: 5 pages, 3 figures To appear in Physical Review A
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Paper: quant-ph/0605252
replaced with revised version Tue, 17 Oct 2006 20:39:02 GMT (740kb)

Title: Photoassociation adiabatic passage of ultracold Rb atoms to form
   ultracold Rb_2 molecules
Authors: Evgeny A. Shapiro, Moshe Shapiro, Avi Pe'er, and Jun Ye
Comments: RevTex, 23 pages, 9 figures
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Paper: cond-mat/0607103
replaced with revised version Tue, 17 Oct 2006 02:46:25 GMT (49kb)

Title: Bose-Condensed Gases in a 1D Optical Lattice at Finite Temperatures
Authors: E. Arahata and T. Nikuni
Comments: Comments: 6 pages, 3 figures, submitted to Quantum Fluids and Solids
   Conference (QFS 2006)
Subj-class: Other
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Paper: cond-mat/0607179
replaced with revised version Tue, 17 Oct 2006 08:09:40 GMT (286kb)

Title: Visualization of vortex bound states in polarized Fermi gases at
Authors: Hui Hu, Xia-Ji Liu, and Peter D. Drummond
Comments: 4 pages, and 4 figures
Subj-class: Superconductivity; Statistical Mechanics
\\ ( , 286kb)
Paper: cond-mat/0607556
replaced with revised version Mon, 16 Oct 2006 23:13:04 GMT (22kb)

Title: Interferences in the density of two initially independent Bose-Einstein
Authors: L. S. Cederbaum, A. I. Streltsov, Y. B. Band, and O. E. Alon
Comments: 13 pages, 2 figures
Subj-class: Other
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Till next week,

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 Wed Oct 25 2006 - 17:26:57 EST

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