# Matt's arXiv selection, Wednesday 18th October 2006.

From: Matthew Davis <mdavis_at_physics.uq.edu.au>
Date: Wed, 18 Oct 2006 17:50:19 +1000 (EST)

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

Getting later in the week again.... 30 new listings this week.

The abstracts:

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Paper: cond-mat/0610187
Date: Fri, 6 Oct 2006 16:59:18 GMT (479kb)

Title: Vortex Formation by Interference of Multiple Trapped Bose-Einstein
Condensates
Authors: David R. Scherer, Chad N. Weiler, Tyler W. Neely, Brian P. Anderson
Subj-class: Other
\\
We report observations of vortex formation as a result of merging together
multiple $^{87}$Rb Bose-Einstein condensates (BECs) in a confining potential.
In this experiment, a trapping potential is partitioned into three sections by
a barrier, enabling the simultaneous formation of three independent,
uncorrelated condensates. The three condensates then merge together into one
BEC, either by removal of the barrier, or during the final stages of
evaporative cooling if the barrier energy is low enough; both processes can
naturally produce vortices within the trapped BEC. We interpret the vortex
formation mechanism as originating in interference between the initially
independent condensates, with indeterminate relative phases between the three
initial condensates and the condensate merging rate playing critical roles in
the probability of observing vortices in the final, single BEC.
\\ ( http://arXiv.org/abs/cond-mat/0610187 , 479kb)
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Paper: quant-ph/0610043
Date: Fri, 6 Oct 2006 15:57:24 GMT (405kb)

Title: KLM quantum computation with bosonic atoms
Authors: Sandu Popescu
\\
A Knill-Laflamme-Milburn (KLM) type quantum computation with bosonic neutral
atoms or bosonic ions is suggested. Crucially, as opposite to other quantum
computation schemes involving atoms (ions), no controlled interactions between
atoms (ions) involving their internal levels are required. Versus photonic KLM
computation this scheme has the advantage that single atom (ion) sources are
more natural than single photon sources, and single atom (ion) detectors are
far more efficient than single photon ones.
\\ ( http://arXiv.org/abs/quant-ph/0610043 , 405kb)
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Paper: cond-mat/0610198
Date: Sat, 7 Oct 2006 09:44:57 GMT (14kb)

Title: Effective Hamiltonian for repulsively bound pairs of particles in a
periodic potential
Authors: David Petrosyan, Michael Fleischhauer, James R. Anglin
Subj-class: Other
\\
Recently, Winkler et al. [Nature 441, 853 (2006)] have predicted and observed
repulsively bound atom pairs in an optical lattice whose dynamics is well
described by the Bose-Hubbard model valid in the tight-binding regime. When the
on-site repulsion between the particles exceeds the single-particle tunneling
rate between the neighboring sites of the periodic potential, such dimer states
are well localized at single sites and are stable on the time scale on which
the energy dissipation in the system can be neglected. Here we derive an
effective Hamiltonian for a lattice containing only even number of particles
per site. We then find that the interaction between dimers is a
nearest-neighbor attraction, which allows for the formation of attractively
bound clusters of repulsively bound pairs of particles.
\\ ( http://arXiv.org/abs/cond-mat/0610198 , 14kb)
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Paper: cond-mat/0610199
Date: Sat, 7 Oct 2006 11:52:59 GMT (203kb)

Title: Vector solitons in nearly-one-dimensional Bose-Einstein condensates
Authors: Luca Salasnich (CNISM and CNR-INFM, Padova) and Boris A. Malomed (Tel
Aviv Univ.)
Comments: 7 pages, 6 figures; Physical Review A, in press
Subj-class: Other
\\
We derive a system of nonpolynomial Schroedinger equations (NPSEs) for
one-dimensional wave functions of two components in a binary self-attractive
Bose-Einstein condensate loaded in a cigar-shaped trap. The system is obtained
by means of the variational approximation, starting from the coupled 3D
Gross-Pitaevskii equations and assuming, as usual, the factorization of 3D wave
functions. The system can be obtained in a tractable form under a natural
condition of symmetry between the two species. A family of vector
(two-component) soliton solutions is constructed. Collisions between orthogonal
solitons (ones belonging to the different components) are investigated by means
of simulations. The collisions are essentially inelastic. They result in strong
excitation of intrinsic vibrations in the solitons, and create a small
orthogonal component ("shadow") in each colliding soliton. The collision may
initiate collapse, which depends on the mass and velocities of the solitons.
\\ ( http://arXiv.org/abs/cond-mat/0610199 , 203kb)
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Paper: cond-mat/0610200
Date: Sun, 8 Oct 2006 03:21:13 GMT (516kb)

Title: Josephson Oscillation and Transition to Self-Trapping for
Bose-Einstein-Condensates in a Triple-Well Trap
Authors: Bin Liu, Li-Bin Fu, Shi-Ping Yang, and Jie Liu
Subj-class: Other
\\
We investigate the tunnelling dynamics of Bose-Einstein-Condensates(BECs) in
a symmetric as well as in a tilted triple-well trap within the framework of
mean-field treatment. The eigenenergies as the functions of the zero-point
energy difference between the tilted wells show a striking entangled star
structure when the atomic interaction is large. We then achieve insight into
the oscillation solutions around the corresponding eigenstates and observe
several new types of Josephson oscillations. With increasing the atomic
interaction, the Josephson-type oscillation is blocked and the self-trapping
solution emerges. The condensates are self-trapped either in one well or in two
wells but no scaling-law is observed near transition points. In particular, we
find that the transition from the Josephson-type oscillation to the
self-trapping is accompanied with some irregular regime where tunnelling
dynamics is dominated by chaos. The above analysis is facilitated with the help
of the Poicar\'{e} section method that visualizes the motions of BECs in a
reduced phase plane.
\\ ( http://arXiv.org/abs/cond-mat/0610200 , 516kb)
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Paper: cond-mat/0610210
Date: Sun, 8 Oct 2006 21:55:51 GMT (122kb)

Title: Time evolution algorithms for Matrix Product States and DMRG
Authors: Juan Jose Garcia-Ripoll
Comments: This work, with 18 pages and 17 figures, is a continuation/extension
of cond-mat/0602305
Subj-class: Strongly Correlated Electrons
\\
In this work we develop several new simulation algorithms for 1D many-body
quantum mechanical systems combining the Matrix Product State variational
ansatz with Taylor, Pad\'e and Arnoldi approximations to the evolution
operator. By comparing with previous techniques based on MPS and DMRG we
demonstrate that the Arnoldi method is the best one, reaching extremely good
accuracy with moderate resources. Finally we apply this algorithm to studying
how correlations are transferred from the atomic to the molecular cloud when
crossing a Feschbach resonance with two-species hard-core bosons in a 1D
optical lattice.
\\ ( http://arXiv.org/abs/cond-mat/0610210 , 122kb)
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Paper: cond-mat/0610221
Date: Mon, 9 Oct 2006 09:19:44 GMT (12kb)

Title: Bose-Einstein condensation of confined and non-interacting Bose
particles
Authors: Sang-Hoon Kim
Subj-class: Statistical Mechanics
\\
Using the grand-canonical statistics of non-interacting bosons in a three
dimensional harmonic trap, the Bose-Einstein condensation was studied.
Mathematical representation was based on Bose integral functions.
The relation between the particle number and its phase transition temperature
was clarified. The chemical potential was plotted. The mean energy and specific
heat which shown a $\lambda$-like sharp transition into the condensation was
studied.
\\ ( http://arXiv.org/abs/cond-mat/0610221 , 12kb)
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Paper: cond-mat/0610225
Date: Mon, 9 Oct 2006 12:55:27 GMT (171kb)

Title: Sequential superradiant scattering from atomic Bose-Einstein condensates
Authors: O. Zobay and G. M. Nikolopoulos
Comments: 9 pages, 4 figures. Submitted to Proceedings of LPHYS'06 workshop
Subj-class: Other
\\
We theoretically discuss several aspects of sequential superradiant
scattering from atomic Bose-Einstein condensates. Our treatment is based on the
semiclassical description of the process in terms of the Maxwell-Schroedinger
equations for the coupled matter-wave and optical fields. First, we investigate
sequential scattering in the weak-pulse regime and work out the essential
mechanisms responsible for bringing about the characteristic fan-shaped
side-mode distribution patterns. Second, we discuss the transition between the
Kapitza-Dirac and Bragg regimes of sequential scattering in the strong-pulse
regime. Finally, we consider the situation where superradiance is initiated by
coherently populating an atomic side mode through Bragg diffraction, as in
studies of matter-wave amplification, and describe the effect on the sequential
scattering process.
\\ ( http://arXiv.org/abs/cond-mat/0610225 , 171kb)
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Paper: cond-mat/0610238
Date: Mon, 9 Oct 2006 18:20:08 GMT (301kb)

Title: Condensation of N interacting bosons: Hybrid approach to condensate
fluctuations
Authors: Anatoly A. Svidzinsky and Marlan O. Scully
Comments: 6 pages, 4 figures, to appear in Phys. Rev. Lett
Subj-class: Statistical Mechanics
\\
We present a new method of calculating the distribution function and
fluctuations for a Bose-Einstein condensate (BEC) of N interacting atoms. The
present formulation combines our previous master equation and canonical
ensemble quasiparticle techniques. It is applicable both for ideal and
interacting Bogoliubov BEC and yields remarkable accuracy at all temperatures.
For the interacting gas of 200 bosons in a box we plot the temperature
dependence of the first four central moments of the condensate particle number
and compare the results with the ideal gas. For the interacting mesoscopic BEC,
as with the ideal gas, we find a smooth transition for the condensate particle
number as we pass through the critical temperature.
\\ ( http://arXiv.org/abs/cond-mat/0610238 , 301kb)
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Paper: cond-mat/0610242
Date: Mon, 9 Oct 2006 19:40:09 GMT (971kb)

Title: Formation of Vortices, Vortex Necklaces and Vortex Rings in Sliced
Condensates
Authors: N. Whitaker, P. G. Kevrekidis, R. Carretero-Gonzalez, D.J.
Frantzeskakis
Subj-class: Soft Condensed Matter
\\
In this Letter, we study the formation of vortices and vortex ring structures
as a result of the interference of higher-dimensional Bose-Einstein condensates
(BECs). This study is motivated by earlier experimental and theoretical studies
in quasi-one-dimensional condensates that produced interference fringes and the
one-dimensional analog of the structures obtained herein, namely dark solitary
waves. We highlight a number of additional possibilities that emerge in the
higher dimensional settings and elucidate their corresponding phenomenology.
For example, a condensate, initially split into eight fragments, gives rise to
a cage'' of vortex rings that surrounds the bulk of the condensed atoms. Our
results should be immediately tractable to currently existing experimental BEC
setups.
\\ ( http://arXiv.org/abs/cond-mat/0610242 , 971kb)
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Paper: quant-ph/0610051
Date: Sun, 8 Oct 2006 17:59:47 GMT (114kb)

Title: A new link between Boson and Fermion algebras: an alternative to
supersymmetry
Authors: Philip Davies
\\
In this paper we describe a new family of algebras which in the case of n = 2
reduces to the Fermion algebra and in the limiting case of n tends to infinity
reduces to the Boson algebra. These generalized algebras describe particles
which obey a generalized exclusion principle, limiting state occupation to
(n-1) and obeying a generalized particle statistics.
\\ ( http://arXiv.org/abs/quant-ph/0610051 , 114kb)
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Paper: quant-ph/0610053
Date: Mon, 9 Oct 2006 05:42:15 GMT (225kb)

Title: Features of Magneto-Optical Resonances in an Elliptically Polarized
Traveling Light Wave
Authors: D.V. Brazhnikov, A.V. Taichenachev, A.M. Tumaikin, V.I. Yudin, S.A.
Zibrov, Ya.O. Dudin, V.V. Vasil'ev, V.L. Velichansky
Journal-ref: D.V. Brazhnikov, A.V. Taichenachev, A.M. Tumaikin, V.I. Yudin,
S.A. Zibrov, Ya.O. Dudin, V.V. Vasil'ev, V.L. Velichansky, JETP Lett. 83(2),
64-68 (2006)
DOI: 10.1134/S0021364006020044
\\
The parameters of nonlinear absorption magneto-optical resonances in the
Hanle configuration have been studied as functions of the ellipticity of a
traveling light wave. It has been found that these parameters (amplitude,
width, and amplitude-to-width ratio) depend strongly on the polarization of the
light wave. In particular, the resonance amplitude can increase by more than an
order of magnitude when the polarization changes from linear to optimal
elliptic. It has been shown that this effect is associated with the Doppler
frequency shift for atoms in a gas. The theoretical results have been
corroborated in experiments in Rb vapor.
\\ ( http://arXiv.org/abs/quant-ph/0610053 , 225kb)
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Paper: quant-ph/0610054
Date: Mon, 9 Oct 2006 06:28:04 GMT (106kb)

Title: Effect of Atomic Coherence on Absorption in Four-level Systems: an
Analytical study
Authors: S N Sandhya
\\
Absorption profile of a four-level ladder atomic system interacting with
three driving fields is studied perturbatively and analytical results are
presented. Numerical results where the driving field strengths are treated upto
all orders are presented. The absorption features is studied in two regimes, i)
the weak middle transition coupling, i.e.
$\Omega_2 << \Omega_{1,3}$ and ii) the strong middle transition coupling
$\Omega_2 >>\Omega_{1,3}$. In case i), it is shown that the ground state
absorption and the saturation characteristics of the population of level 2
reveal deviation due to the presence of upper level couplings. In particular,
the saturation curve for the population of level 2 shows a dip for $\Omega_1 = \Omega_3$. While the populations of levels 3 and 4 show a maxima when this
resonance condition is satisfied. Thus the resonance condition provides a
criterion for maximally populating the upper levels. A second order
perturbation calculation reveals the nature of this minima (maxima). In the
second case, I report two important features: a) Filtering of the Aulter-Townes
doublet in the three-peak absorption profile of the ground state, which is
achieved by detuning only the upper most coupling field, and b) control of
line-width by controlling the strength of the upper coupling fields. This
filtering technique coupled with the control of linewidth could prove to be
very useful for high resolution studies.
\\ ( http://arXiv.org/abs/quant-ph/0610054 , 106kb)
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Paper: quant-ph/0610056
Date: Mon, 9 Oct 2006 10:47:06 GMT (136kb)

Title: Adiabatic Elimination in a Lambda System
Authors: E. Brion, L.H. Pedersen and K. Molmer
\\
This paper deals with different ways to extract the effective two-dimensional
lower level dynamics of a lambda system excited by off-resonant laser beams. We
present a commonly used procedure for elimination of the upper level, and we
show that it may lead to ambiguous results. To overcome this problem and better
understand the applicability conditions of this scheme, we review two rigorous
methods which allow us both to derive an unambiguous effective two-level
Hamiltonian of the system and to quantify the accuracy of the approximation
achieved: the first one relies on the exact solution of the Schrodinger
equation, while the second one resorts to the Green's function formalism and
the Feshbach projection operator technique.
\\ ( http://arXiv.org/abs/quant-ph/0610056 , 136kb)
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Paper: cond-mat/0610256
Date: Tue, 10 Oct 2006 08:49:37 GMT (13kb)

Title: Density functional theory of the trapped Fermi gas in the unitary regime
Authors: Brandon P. van Zyl, D. A. W. Hutchinson and Melodie Need
Subj-class: Other; Statistical Mechanics
\\
We investigate a density-functional theory (DFT) approach for an unpolarized
trapped dilute Fermi gas in the unitary limit . A reformulation of the recent
work of T. Papenbrock [Phys. Rev. A, {\bf 72}, 041602(R) (2005)] in the
language of fractional exclusion statistics allows us to obtain an estimate of
the universal factor, $\xi_{3D}$, in three dimensions (3D), in addition to
providing a systematic treatment of finite-$N$ corrections. We show that in 3D,
finite-$N$ corrections lead to unphysical values for $\xi_{3D}$, thereby
suggesting that a simple DFT applied to a small number of particles may not be
suitable in 3D. We then perform an analogous calculation for the
two-dimensional (2D) system in the infinite-scattering length regime, and
obtain a value of $\xi_{2D}=1$. Owing to the unique properties of the
Thomas-Fermi energy density-functional in 2D our result, in contrast to 3D, is
{\em exact} and therefore requires no finite-$N$ corrections.
\\ ( http://arXiv.org/abs/cond-mat/0610256 , 13kb)
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Paper: cond-mat/0610262
Date: Tue, 10 Oct 2006 10:18:09 GMT (62kb)

Title: Quasiperiodically driven ratchets for cold atoms
Authors: R. Gommers, S. Denisov and F. Renzoni
Comments: misprint in the label of Fig. 4 corrected
Subj-class: Statistical Mechanics; Mesoscopic Systems and Quantum Hall Effect
Journal-ref: Phys. Rev. Lett. 96, 240604 (2006)
\\
We investigate experimentally the route to quasiperiodicity in a driven
ratchet for cold atoms, and examine the relationship between symmetries and
transport while approaching the quasiperiodic limit. Depending on the specific
form of driving, quasiperiodicity results in the complete suppression of
transport, or into the restoration of the symmetries which hold for a periodic
driving.
\\ ( http://arXiv.org/abs/cond-mat/0610262 , 62kb)
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Paper: cond-mat/0610274
Date: Tue, 10 Oct 2006 16:51:01 GMT (59kb)

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
Subj-class: Strongly Correlated Electrons; Superconductivity
\\
We study the single-plane-wave Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) states
for BCS--Bose-Einstein condensation (BEC) crossover at general temperatures
$T$. Because we include the important effects of noncondensed pairs, our $T \neq 0$ phase diagrams are different from those reported in earlier work. We
find that generalized LOFF phases may be the ground state for a wide range of
(weak through moderately strong) interactions, including the unitary regime.
However, these LOFF phases are readily destroyed by non-zero $T$.
\\ ( http://arXiv.org/abs/cond-mat/0610274 , 59kb)
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Paper: quant-ph/0610029
Date: Thu, 5 Oct 2006 01:49:38 GMT (880kb)

Title: Cavity QED determination of atomic number statistics in optical lattices
Authors: W. Chen, D. Meiser, and P. Meystre
Comments: 10 pages revtex, 13 figures
Subj-class: Quantum Physics; Other; Atomic Physics
\\
We study the reflection of two counter-propagating modes of the light field
in a ring resonator by ultracold atoms either in the Mott insulator state or in
the superfluid state of an optical lattice. We obtain exact numerical results
for a simple two-well model and carry out statistical calculations appropriate
for the full lattice case. We find that the dynamics of the reflected light
strongly depends on both the lattice spacing and the state of the matter-wave
field. Depending on the lattice spacing, the light field is sensitive to
various density-density correlation functions of the atoms. The light field and
the atoms become strongly entangled if the latter are in a superfluid state, in
which case the photon statistics typically exhibit complicated multimodal
structures.
\\ ( http://arXiv.org/abs/quant-ph/0610029 , 880kb)
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Paper: quant-ph/0610064
Date: Tue, 10 Oct 2006 04:16:33 GMT (659kb)

Title: Measuring the quantum statistics of an atom laser beam
Authors: A. S. Bradley, M. K. Olsen, S. A. Haine and J. J. Hope
\\
We propose and analyse a scheme for measuring the quadrature statistics of an
atom laser beam using extant optical homodyning and Raman atom laser
techniques. Reversal of the normal Raman atom laser outcoupling scheme is used
to map the quantum statistics of an incoupled beam to an optical probe beam. A
multimode model of the spatial propagation dynamics shows that the Raman
incoupler gives a clear signal of de Broglie wave quadrature squeezing for both
pulsed and continuous inputs. Finally, we show that experimental realisations
of the scheme may be tested with existing methods via measurements of Glauber's
intensity correlation function.
\\ ( http://arXiv.org/abs/quant-ph/0610064 , 659kb)
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Paper: quant-ph/0610067
Date: Tue, 10 Oct 2006 10:27:15 GMT (106kb)

Title: Optical excitation spectrum of an atom in a surface-induced potential
Authors: Fam Le Kien, S. Dutta Gupta, and K. Hakuta
\\
We study the optical excitation spectrum of an atom in the vicinity of a
dielectric surface. We calculate the rates of the total scattering and the
scattering into the evanescent modes. With a proper assessment of the
limitations, we demonstrate the portability of the flat-surface results to an
experimental situation with a nanofiber. The effect of the surface-induced
be weak. On the contrary, the effect for bound-to-bound transitions is
significant leading to a large excitation linewidth, a substantial negative
shift of the peak position, and a strong long tail on the negative side and a
small short tail on the positive side of the field--atom frequency detuning.
\\ ( http://arXiv.org/abs/quant-ph/0610067 , 106kb)
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Paper: quant-ph/0610068
Date: Tue, 10 Oct 2006 10:45:55 GMT (329kb)

Title: Spontaneous radiative decay of translational levels of an atom near a
dielectric surface
Authors: Fam Le Kien and K. Hakuta
\\
We study spontaneous radiative decay of translational levels of an atom in
the vicinity of a semi-infinite dielectric. We systematically derive the
microscopic dynamical equations for the spontaneous decay process. We calculate
analytically and numerically the radiative linewidths and the spontaneous
transition rates for the translational levels. The roles of the interference
between the emitted and reflected fields and of the transmission into the
evanescent modes are clearly identified. Our numerical calculations for the
silica--cesium interaction show that the radiative linewidths of the bound
excited levels with large enough but not too large vibrational quantum numbers
are moderately enhanced by the emission into the evanescent modes and those for
the deep bound levels are substantially reduced by the surface-induced red
shift of the transition frequency.
\\ ( http://arXiv.org/abs/quant-ph/0610068 , 329kb)
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Paper: quant-ph/0610071
Date: Tue, 10 Oct 2006 13:37:15 GMT (296kb)

Title: Diffraction limited optics for single atom manipulation
Authors: Y.R.P. Sortais, H. Marion, C. Tuchendler, A.M. Lance, M. Lamare, P.
Fournet, C. Armellin, R. Mercier, G. Messin, A. Browaeys and P. Grangier
\\
We present an optical system designed to capture and observe a single neutral
atom in an optical dipole trap, created by focussing a laser beam using a large
numerical aperture N.A.=0.5 aspheric lens. We experimentally evaluate the
performance of the optical system and show that it is diffraction limited over
a broad spectral range (~ 200 nm) with a large transverse field (+/- 25
microns). The optical tweezer created at the focal point of the lens is able to
trap single atoms of 87Rb and to detect them individually with a large
collection efficiency. We measure the oscillation frequency of the atom in the
dipole trap, and use this value as an independent determination of the waist of
the optical tweezer. Finally, we produce with the same lens two dipole traps
separated by 2.2 microns and show that the imaging system can resolve the two
atoms.
\\ ( http://arXiv.org/abs/quant-ph/0610071 , 296kb)
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Paper: quant-ph/0610073
Date: Tue, 10 Oct 2006 15:32:15 GMT (68kb)

Title: Cavity enhanced light scattering in optical lattices to probe atomic
quantum statistics
Authors: Igor B. Mekhov, Christoph Maschler, Helmut Ritsch
\\
Different quantum states of atoms in optical lattices can be nondestructively
monitored through off-resonant light scattering into a cavity mode. Angle
resolved measurements of photon number and variance provide information about
site. Scattering into a standing-wave mode shows structure at angles where
classical diffraction gives zero. In particular for transverse illumination no
photons are scattered into a cavity for a Mott insulator, while the photon
number is proportional to the atom number for a superfluid.
\\ ( http://arXiv.org/abs/quant-ph/0610073 , 68kb)
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Paper: cond-mat/0610308
Date: Wed, 11 Oct 2006 17:02:06 GMT (33kb)

Title: Exact results for a charged, harmonically trapped quantum gas at
arbitrary temperature and magnetic field strength
Authors: Patrick Shea and Brandon P. van Zyl
Comments: To appear in Phys. Rev. B
Subj-class: Statistical Mechanics
\\
An analytical expression for the first-order density matrix of a charged,
two-dimensional, harmonically confined quantum gas, in the presence of a
constant magnetic field is derived. In contrast to previous results available
in the literature, our expressions are exact for any temperature and magnetic
field strength. We also present a novel factorization of the Bloch density
matrix in the form of a simple product with a clean separation of the
zero-field and field-dependent parts. This factorization provides an
alternative way of analytically investigating the effects of the magnetic field
on the system, and also permits the extension of our analysis to other
dimensions, and/or anisotropic confinement.
\\ ( http://arXiv.org/abs/cond-mat/0610308 , 33kb)
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Paper: cond-mat/0610314
Date: Wed, 11 Oct 2006 19:43:46 GMT (19kb)

Title: Energy-dependent effective interactions for dilute many-body systems
Authors: A. Collin, P. Massignan, and C. J. Pethick
Report-no: NORDITA-2006-34
Subj-class: Other
\\
We address the issue of determining an effective two-body interaction for
mean-field calculations of energies of many-body systems. We show that the
effective interaction is proportional to the phase shift, and demonstrate this
result in the quasiclassical approximation when there is a trapping potential
in addition to the short-range interaction between a pair of particles. We
calculate numerically energy levels for the case of an interaction with a
short-range square-well and a harmonic trapping potential and show that the
numerical results agree well with the analytical expression. We derive a
generalized Gross--Pitaevskii equation which includes effective range
corrections and discuss the form of the electron--atom effective interaction to
be used in calculations of Rydberg atoms and molecules.
\\ ( http://arXiv.org/abs/cond-mat/0610314 , 19kb)
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Paper: quant-ph/0610087
Date: Wed, 11 Oct 2006 09:45:06 GMT (532kb)

Title: Controlled Single-Photon Emission from a Single Trapped Two-Level Atom
Authors: Benoit Darqui\'{e} (LCFIO), Matthew Jones (LCFIO), Jos Dingjan
(LCFIO), Jerome Beugnon (LCFIO), Silvia Bergamini (LCFIO), Yvan Sortais
(LCFIO), Gaetan Messin (LCFIO), Antoine Browaeys (LCFIO), Philippe Grangier
(LCFIO)
Proxy: ccsd ccsd-00094645
Journal-ref: Science 309 (2005) 454
\\
By illuminating an individual rubidium atom stored in a tight optical tweezer
with short resonant light pulses, we create an efficient triggered source of
single photons with a well-defined polarization. The measured intensity
correlation of the emitted light pulses exhibits almost perfect antibunching.
Such a source of high rate, fully controlled single photon pulses has many
potential applications for quantum information processing.
\\ ( http://arXiv.org/abs/quant-ph/0610087 , 532kb)
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Paper (*cross-listing*): gr-qc/0610047
Date: Tue, 10 Oct 2006 18:03:28 GMT (58kb)

Title: Testing General Relativity with Atom Interferometry
Authors: Savas Dimopoulos, Peter W. Graham, Jason M. Hogan, Mark A. Kasevich
Subj-class: General Relativity and Quantum Cosmology; Atomic Physics
\\
The unprecedented precision of atom interferometry will soon lead to
laboratory tests of general relativity to levels that will rival or exceed
those reached by astrophysical observations. We propose such an experiment that
will initially test the equivalence principle to 1 part in 10^15 (300 times
better than the current limit), and 1 part in 10^17 in the future. It will also
probe general relativistic effects--such as the non-linear three-graviton
coupling, the gravity of an atom's kinetic energy, and the falling of light--to
several decimals. Further, in contrast to astrophysical observations,
laboratory tests can isolate these effects via their different functional
dependence on experimental variables.
\\ ( http://arXiv.org/abs/gr-qc/0610047 , 58kb)
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Paper: cond-mat/0610317
Date: Wed, 11 Oct 2006 20:25:40 GMT (61kb)

Title: Miscibility in a degenerate fermionic mixture induced by linear coupling
Comments: 9 pages, 12 figures, PRA (in press)
Subj-class: Soft Condensed Matter
\\
We consider a one-dimensional mean-field-hydrodynamic model of a
two-component degenerate Fermi gas in an external trap, each component
representing a spin state of the same atom. We demonstrate that the
interconversion between them (linear coupling), imposed by a resonant
electromagnetic wave, transforms the immiscible binary gas into a miscible
state, if the coupling constant, $\kappa$, exceeds a critical value, $\kappa _{\mathrm{cr}}$. The effect is predicted in a variational approximation, and
confirmed by numerical solutions. Unlike the recently studied model of a binary
BEC with the linear coupling, the components in the immiscible phase of the
binary fermion mixture never fill two separated domains with a wall between
them, but rather form anti-locked ($\pi$ -phase-shifted) density waves.
Another difference from the bosonic mixture is spontaneous breaking of symmetry
between the two components in terms of numbers of atoms in them, $N_{1}$ and
$N_{2}$. The latter effect is characterized by the parameter $\nu \equiv (N_{1}-N_{2})/(N_{1}+N_{2})$ (only $N_{1}+N_{2}$ is a conserved quantity), the
onset of miscibility at $\kappa \geq \kappa_{\mathrm{cr}}$ meaning a transition
to $\nu \equiv 0$. At $\kappa <\kappa_{\mathrm{cr}}$, $\nu$ features damped
oscillations as a function of $\kappa$. We also briefly consider an asymmetric
model, with a chemical-potential difference between the two components.
\\ ( http://arXiv.org/abs/cond-mat/0610317 , 61kb)
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\\
Paper: cond-mat/0610345
Date: Thu, 12 Oct 2006 15:38:01 GMT (38kb)

Title: Collective mode description for a clean Fermi gas with a 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
Subj-class: Strongly Correlated Electrons; Disordered Systems and Neural
Networks
\\
We discuss a recent bosonization method developed to study clean Fermi gases
with a repulsion in any dimensions. The method enables one to consider both
density and spin excitations. It is demonstrated that due to a non-abelian
structure of the effective theory, the spin excitations interact with each
other, which leads to new logarithmic in temperature corrections to physical
quantities. Using a renormalization group scheme constructed for the effective
low energy field theory these logarithms are summed up in all orders.
Temperature dependent corrections to the specific heat and spin susceptibility
are obtained for all dimensions d=1,2,3.
\\ ( http://arXiv.org/abs/cond-mat/0610345 , 38kb)
------------------------------------------------------------------------------
\\
Paper: quant-ph/0610095
Date: Thu, 12 Oct 2006 09:41:52 GMT (2kb)

Title: Comment on Spin Decoherence in Superconducting Atom Chips'
Authors: Stefan Scheel, E. A. Hinds, and P. L. Knight
\\
We comment on a recent paper [Phys. Rev. Lett. 97, 070401 (2006)] concerning
rubidium atoms trapped near a superconducting niobium surface at ~4K. This
seeks to calculate the rate of atomic spin flips induced by thermal magnetic
noise. We point out that the calculation is in error by a large factor because
it is based on the two-fluid model of superconductivity. This model gives a
poor description of electromagnetic dissipation just below the critical
temperature because it cannot incorporate the case II coherences of a fuller
quantum theory.
\\ ( http://arXiv.org/abs/quant-ph/0610095 , 2kb)
------------------------------------------------------------------------------
\\
Paper: quant-ph/0610099
Date: Thu, 12 Oct 2006 13:58:24 GMT (248kb)

Title: A class of quantum many-body states that can be efficiently simulated
Authors: G. Vidal
\\
We introduce the multi-scale entanglement renormalization ansatz (MERA), an
efficient representation of certain quantum many-body states on a D-dimensional
lattice. Equivalent to a quantum circuit with logarithmic depth and distinctive
causal structure, the MERA allows for an exact evaluation of local expectation
values. It is also the structure underlying entanglement renormalization, a
coarse-graining scheme for quantum systems on a lattice that is focused on
preserving entanglement.
\\ ( http://arXiv.org/abs/quant-ph/0610099 , 248kb)
------------------------------------------------------------------------------

Replaced papers:

------------------------------------------------------------------------------
\\
Paper: cond-mat/0606151
replaced with revised version Fri, 6 Oct 2006 18:53:48 GMT (67kb)

Title: Structure of vortices in rotating Bose-Einstein condensates
Authors: Gentaro Watanabe, S. Andrew Gifford, Gordon Baym, C. J. Pethick
Report-no: NORDITA-2006-15
Subj-class: Other; Mesoscopic Systems and Quantum Hall Effect
\\ ( http://arXiv.org/abs/cond-mat/0606151 , 67kb)
------------------------------------------------------------------------------
\\
Paper: cond-mat/0607138
replaced with revised version Fri, 6 Oct 2006 19:26:16 GMT (191kb)

Title: Color superfluidity and "baryon" formation in ultracold fermions
Authors: Akos Rapp, Gergely Zarand, Carsten Honerkamp, Walter Hofstetter
Comments: 5 PRL pages, 2 figures
Subj-class: Strongly Correlated Electrons; Superconductivity
\\ ( http://arXiv.org/abs/cond-mat/0607138 , 191kb)
------------------------------------------------------------------------------
\\
Paper: cond-mat/0607160
replaced with revised version Fri, 6 Oct 2006 13:21:22 GMT (60kb)

Title: Stability and excitations of solitons in 2D Bose-Einstein condensates
Authors: S. Tsuchiya, F. Dalfovo, C. Tozzo, and L. Pitaevskii
Comments: 6 pages, 2 figures, minor corrections, Proceedings of QFS 2006, to be
published in JLTP
Subj-class: Other
\\ ( http://arXiv.org/abs/cond-mat/0607160 , 60kb)
------------------------------------------------------------------------------
\\
Paper (*cross-listing*): math-ph/0605002
replaced with revised version Fri, 6 Oct 2006 16:40:48 GMT (47kb)

Title: Feynman cycles in the Bose gas
Authors: Daniel Ueltschi
Subj-class: Mathematical Physics; Statistical Mechanics
MSC-class: 82B10; 82B21; 82B26; 82D50
\\ ( http://arXiv.org/abs/math-ph/0605002 , 47kb)
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\\
Paper: cond-mat/0510630
replaced with revised version Sat, 7 Oct 2006 10:20:57 GMT (25kb)

Title: Feshbach spectroscopy of a K-Rb atomic mixture
Authors: Francesca Ferlaino, Chiara D'Errico, Giacomo Roati, Matteo Zaccanti,
Massimo Inguscio, Giovanni Modugno, Andrea Simoni
Subj-class: Other
Journal-ref: Phys. Rev. A 73, 040702(R) (2006) and Erratum
\\ ( http://arXiv.org/abs/cond-mat/0510630 , 25kb)
------------------------------------------------------------------------------
\\
Paper: quant-ph/0608109
replaced with revised version Mon, 9 Oct 2006 15:53:13 GMT (68kb)

Title: Controlled splitting of an atomic wave packet
Authors: M. Zhang, P. Zhang, M. S. Chapman and L. you
Comments: 4 pages, 4 figures. Accepted by Phys. Rev. Lett
Journal-ref: Phys. Rev. Lett. 97, 070403 (2006)
\\ ( http://arXiv.org/abs/quant-ph/0608109 , 68kb)
------------------------------------------------------------------------------
\\
Paper: quant-ph/0610019
replaced with revised version Mon, 9 Oct 2006 12:08:45 GMT (325kb)

Title: Realization of a superconducting atom chip
Authors: Thomas Nirrengarten (LKB - Lhomond), Angie Qarry (LKB - Lhomond),
C\'{e}dric Roux (LKB - Lhomond), Andreas Emmert (LKB - Lhomond), Gilles
Nogues (LKB - Lhomond), Michel Brune (LKB - Lhomond), Jean-Michel Raimond
(LKB - Lhomond), Serge Haroche (LKB - Lhomond, CDF)
Comments: Submitted to Phys. Rev. Lett
Proxy: ccsd ccsd-00103290
\\ ( http://arXiv.org/abs/quant-ph/0610019 , 325kb)
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\\
Paper (*cross-listing*): math-ph/0606058
replaced with revised version Tue, 10 Oct 2006 09:01:12 GMT (25kb)

Title: Rapidly Rotating Bose-Einstein Condensates in Strongly Anharmonic Traps
Authors: M. Correggi, T. Rindler-Daller, J. Yngvason
Comments: LaTex2e, 27 pages, slightly revised version, typos fixed
Subj-class: Mathematical Physics; Statistical Mechanics
MSC-class: 35Q55, 47J30, 76M23
\\ ( http://arXiv.org/abs/math-ph/0606058 , 25kb)
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\\
Paper: cond-mat/0606743
replaced with revised version Wed, 11 Oct 2006 18:57:03 GMT (61kb)

Title: Prediction of quantum stripe ordering in optical lattices
Authors: Congjun Wu, W. Vincent Liu, Joel Moore, and Sankar Das Sarma
Comments: 4 pages, three figures, accepted by Phys. Rev. Lett
Subj-class: Strongly Correlated Electrons; Superconductivity
\\ ( http://arXiv.org/abs/cond-mat/0606743 , 61kb)
------------------------------------------------------------------------------
\\
Paper: cond-mat/0607459
replaced with revised version Wed, 11 Oct 2006 22:23:14 GMT (257kb)

Title: Superfluidity in Three-species Mixture of Fermi Gases across Feshbach
Resonances
Authors: Hui Zhai
Comments: 4 pages, 3 figures, revised version
Subj-class: Superconductivity
\\ ( http://arXiv.org/abs/cond-mat/0607459 , 257kb)
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\\
Paper: cond-mat/0608255
replaced with revised version Wed, 11 Oct 2006 22:40:29 GMT (262kb)

Title: FFLO Vortex Lattice States in Cold Fermionic-Atom Systems
Authors: Y.-P. Shim, R. A. Duine, and A. H. MacDonald
Comments: 10 pages, 9 figures, accepted for publication in Phys. Rev. A
Subj-class: Statistical Mechanics
\\ ( http://arXiv.org/abs/cond-mat/0608255 , 262kb)
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\\
Paper: cond-mat/0609748
replaced with revised version Thu, 12 Oct 2006 17:35:58 GMT (42kb)

Title: Quantum Noise Analysis of Spin Systems Realized with Cold Atoms
Authors: R. W. Cherng, Eugene Demler
Comments: 18 pages, 4 figures, updated acknowledgements
Subj-class: Strongly Correlated Electrons; Statistical Mechanics
\\ ( http://arXiv.org/abs/cond-mat/0609748 , 42kb)
------------------------------------------------------------------------------

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 Wed Oct 18 2006 - 17:50:19 EST

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