Matt's arXiv selection: week ending 26 January 2007.

From: Matthew Davis <>
Date: Fri, 2 Feb 2007 05:26:44 +1000 (EST)

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

... and the second email - a more reasonable 19 new preprints

Paper: cond-mat/0701464
Date: Thu, 18 Jan 2007 22:14:54 GMT (68kb)

Title: Spatial distortion of trapped Fermi gases
Authors: Masudul Haque, H.T.C. Stoof
Categories: cond-mat.mes-hall cond-mat.supr-con
Comments: 4+ pages, 3 figures. Formalism for distorted trapped fermi systems +
   treatment of polarized fermion experiments
Subj-class: Mesoscopic Systems and Quantum Hall Effect; Superconductivity
   We present a general approach for calculating densities and other local
quantities of trapped Fermi gases, when the cloud shape is distorted with
respect to the trap shape due to global energy considerations. Our approach
provides a consistent way to explore physics beyond the local density
approximation, if this is necessary due to the distortion. We illustrate this
by analyzing in detail experimentally observed distortions in an imbalanced
Fermi mixture in an elongated trap. In particular, we demonstrate in that case
dramatic deviations from ellipsoidal cloud shapes arising from the competition
between surface and bulk energies.
\\ ( , 68kb)
Paper: cond-mat/0701471
Date: Fri, 19 Jan 2007 06:40:31 GMT (63kb)

Title: Anomalous fermion bunching in density-density correlation
Authors: Hongwei Xiong; Shujuan Liu
Categories: cond-mat.other cond-mat.stat-mech
Comments: RevTex, 4 pages
Subj-class: Other; Statistical Mechanics
   We consider theoretically density-density correlation of identical Fermi
system by including the finite resolution of a detector and delta-function term
omitted in the ordinary method. We find an anomalous fermion bunching effect,
which is a quantum effect having no classical analogue. This anomalous fermion
bunching is studied for ultracold Fermi gases released from a three-dimensional
optical lattices. It is found that this anomalous fermion bunching is supported
by a recent experiment (T. Rom et al Nature 444, 733 (2006)).
\\ ( , 63kb)
Paper: cond-mat/0701476
Date: Fri, 19 Jan 2007 13:00:11 GMT (100kb)

Title: Unconventional Transition from Superfluid to Mott Insulator Phase of
   Hard-Core Bosons on the Checkerboard Lattice
Authors: Arnab Sen, Kedar Damle and T. Senthil
Categories: cond-mat.str-el
Comments: 11 pages, PRB format
Subj-class: Strongly Correlated Electrons
   We study hard-core bosons on the checkerboard lattice with nearest neighbour
unfrustrated hopping $t$ and `tetrahedral' plaquette charging energy $U$.
Analytical arguments and Quantum Monte Carlo simulations lead us to the
conclusion that the system undergoes a zero temperature ($T$) quantum phase
transition from a superfluid phase at small $U/t$ to a large $U/t$ Mott
insulator phase with $\rho$ = 1/4 for a range of values of the chemical
potential $\mu$. Further, the quarter-filled insulator breaks lattice
translation symmetry in a characteristic four-fold ordering pattern, and
occupies a lobe of finite extent in the $\mu$-$U/t$ phase diagram. A Quantum
Monte-Carlo study slightly away from the tip of the lobe provides evidence for
a direct weakly first-order superfluid-insulator transition. However, a
combination of indirect numerical evidence and analytical arguments leads us to
conclude that the transition {\em at} the tip of the lobe belongs to a
different landau-forbidden second-order universality class.
\\ ( , 100kb)
Paper: cond-mat/0701481
Date: Fri, 19 Jan 2007 16:05:44 GMT (559kb)

Title: The effects of optically induced non-Abelian gauge field in cold atoms
Authors: Li-Hua Lu and You-Quan Li
Categories: cond-mat.other cond-mat.mes-hall
Comments: Revtex 6 pages, 2 figures
Subj-class: Other; Mesoscopic Systems and Quantum Hall Effect
   We present a general description that $N-1$ degenerate dark states can be
generated by coupling $N$-fold degenerate ground states and a common excited
state with $N$ laser fields. Interferences between light waves with different
frequencies can produce laser fields with time-dependent amplitudes, which can
induce not only U(N) non-Abelian vector fields but also the scalar ones for the
adiabatic motion of atoms in such laser fields. As an example, a time-periodic
gauge potential is produced by applying specific laser fields to a tripod
system. Some features of the Landau levels and the ground-state phase diagram
of a rotating Bose-Einstein condensate for a concrete gauge field are also
\\ ( , 559kb)
Paper: cond-mat/0701484
Date: Fri, 19 Jan 2007 18:36:17 GMT (44kb)

Title: Finite temperature phase diagram of a polarized Fermi gas in an optical
Authors: T.K. Koponen, T. Paananen, J.-P. Martikainen, and P. Torma
Categories: cond-mat.supr-con cond-mat.other
Comments: 4 pages, 3 figures
Subj-class: Superconductivity; Other
   We present phase diagrams for a polarized Fermi gas in an optical lattice as
a function of temperature, polarization, and lattice filling factor. We
consider the possibility of the Fulde-Ferrel-Larkin-Ovchinnikov (FFLO) phase,
Sarma or the breached pair (BP) phase, the BCS phase, the normal state, as well
as a phase separation (PS) where the BCS phase occupies one part of the volume
and the normal phase the other. We calculate the phase diagrams also at
non-zero temperatures. We show that the FFLO phase appears in a considerable
portion of the phase diagram: at zero temperature, phase separation dominates
for low polarizations, the FFLO phase appears after a critical polarization,
and the system makes a transition into a normal phase at an even higher
polarization. Phase separation ceases to exists at a certain temperature after
which the FFLO, BP, or the normal phase dominates. The phase diagrams show two
critical points of different nature. We show how various phases leave clear
signatures to the momentum distributions of the atoms which can be observed
after time of flight expansion.
\\ ( , 44kb)
Paper: physics/0701223
Date: Fri, 19 Jan 2007 14:25:34 GMT (74kb)

Title: Variance minimization variational Monte Carlo method
Authors: Imran Khan and Bo Gao
Categories: physics.comp-ph physics.atom-ph
Comments: 5 pages, 3 figures
Subj-class: Computational Physics; Atomic Physics
   We present a variational Monte Carlo (VMC) method that works equally well for
the ground and the excited states of a quantum system. The method is based on
the minimization of the variance of energy, as opposed to the energy itself in
standard methods. As a test, it is applied to the investigation of the
universal spectrum at the van der Waals length scale for two identical Bose
atoms in a symmetric harmonic trap, with results compared to the basically
exact results obtained from a multiscale quantum-defect theory.
\\ ( , 74kb)
Paper: physics/0701231
Date: Fri, 19 Jan 2007 17:20:57 GMT (154kb)

Title: Self-citation corrections for the Hirsch index
Authors: Michael Schreiber
Categories: physics.soc-ph
Comments: 6 pages, 6 figures, submitted to EPL
Subj-class: Physics and Society
   I propose to sharpen the index h, proposed by Hirsch as a useful index to
characterize the scientific output of a researcher, by excluding the
self-citations. Performing a self-experiment and also analyzing two anonymous
data sets, it is shown that self-citations can significantly reduce the $h$
index in contrast to Hirsch's expectations.
\\ ( , 154kb)
Paper: cond-mat/0701502
Date: Sun, 21 Jan 2007 08:20:17 GMT (171kb)

Title: Quantum dynamics of repulsively bound atom pairs in an optical lattice
Authors: Li Wang, Yajiang Hao, Shu Chen
Categories: cond-mat.other
Comments: 5 pages, 5 figures
Subj-class: Other
   In this paper, we investigate the quantum dynamics of repulsively bound atom
pairs in an optical lattice described by the periodic Bose-Hubbard model by
using the exact diagonalization method. It is shown that how the dynamic
evolution of an initially confined system is affected by the on-site
interaction and the choice of the initial state. Our results are in qualitative
agreement with the corresponding experiment recently carried out in Innsbruck.
We also study the dynamics of a system in which all the particles are initially
loaded into only one optical lattice site and find that with the increasing of
the on-site interaction, the system displays a kind of self-trapping.
\\ ( , 171kb)
Paper: cond-mat/0701506
Date: Mon, 22 Jan 2007 16:37:41 GMT (15kb)

Title: Fractional Spin Hall Effect in Bosonic Atomic Gas
Authors: Xiong-Jun Liu, Xin Liu, L. C. Kwek and C. H. Oh
Categories: cond-mat.mes-hall
Comments: 5 pages, 1 figure
Subj-class: Mesoscopic Systems and Quantum Hall Effect
   We propose fractional spin hall effect (FSHE) in bosonic atomic system by
coupling the atomic spins to optical fields. The present scheme is an extension
to bosonic system of the recent work [7] on optically induced spin hall effect
in fermionic atomic system. The system has two different types of ground
states. The 1st type of ground state is a 1/3-factor Laughlin function, and has
the property of chiral - anti-chiral interchange antisymmetry, while the 2nd
type is shown to be a 1/4-factor Laughlin function with chiral - anti-chiral
symmetry. The experimental realization of the present model is also discussed.
\\ ( , 15kb)
Paper: quant-ph/0701148
Date: Sun, 21 Jan 2007 04:48:45 GMT (313kb)

Title: Inelastic collisions in an exactly solvable two-mode Bose-Einstein
Authors: I. Fuentes-Schuller, P. Barberis-Blostein
Categories: quant-ph
   Inelastic collisions occur in Bose-Einstein condensates, in some cases,
producing particle loss in the system. Nevertheless, these processes have not
been studied in the case when particles do not escape the trap. We show that
such inelastic processes are relevant in quantum properties of the system such
as the evolution of the relative population, the self trapping effect and the
probability distribution of particles. Moreover, including inelastic terms in
the model of the two-mode condensate allows for an exact analytical solution.
Using this solution, we show that collisions favor the generation of
entanglement between the modes of the condensate as long as the collision rate
does not exceed the natural frequency of the system.
\\ ( , 313kb)
Paper: quant-ph/0701158
Date: Mon, 22 Jan 2007 12:41:35 GMT (431kb)

Title: Phase detection at the quantum limit with multi-photon Mach-Zehnder
Authors: L. Pezze (BEC-CNR-Infm), A. Smerzi (BEC-CNR-Infm), G. Khoury (UCSB),
   J. F. Hodelin (UCSB) and D. Bouwmeester (UCSB)
Categories: quant-ph
Comments: 4 pages, 5 figures
   We study a Mach-Zehnder interferometer fed by a coherent state in one input
port and vacuum in the other. We explore a Bayesian phase estimation strategy
to demonstrate that it is possible to achieve the standard quantum limit
independently from the true value of the phase shift and specific assumptions
on the noise of the interferometer. We have been able to implement the protocol
using parallel operation of two photon-number-resolving detectors and
multiphoton coincidence logic electronics at the output ports of a
weakly-illuminated Mach-Zehnder interferometer. This protocol is unbiased and
saturates the Cramer-Rao phase uncertainty bound and, therefore, is an optimal
phase estimation strategy.
\\ ( , 431kb)
Paper: quant-ph/0701167
Date: Tue, 23 Jan 2007 13:39:22 GMT (511kb)

Title: Cold Atom Physics Using Ultra-Thin Optical Fibers: Light-Induced Dipole
   Forces and Surface Interactions
Authors: G. Sagu\'{e}, E. Vetsch, W. Alt, D. Meschede and A. Rauschenbeutel
Categories: quant-ph
Comments: 4 pages, 5 figures
   The strong evanescent field around ultra-thin unclad optical fibers bears a
high potential for detecting, trapping, and manipulating cold atoms.
Introducing such a fiber into a cold atom cloud, we investigate the interaction
of a small number of cold Caesium atoms with the guided fiber mode and with the
fiber surface. Using high resolution spectroscopy, we observe and analyze
light-induced dipole forces, van der Waals interaction, and a significant
enhancement of the spontaneous emission rate of the atoms. The latter can be
assigned to the modification of the vacuum modes by the fiber.
\\ ( , 511kb)
Paper: physics/0701263
Date: Tue, 23 Jan 2007 17:11:53 GMT (904kb)

Title: Laser-trapping of Ra-225 and Ra-226 with repumping by room temperature
   blackbody radiation
Authors: J. R. Guest, N. D. Scielzo, I. Ahmad, K. Bailey, J. P. Greene, R. J.
   Holt, Z.-T. Lu, T. P. O'Connor, D. H. Potterveld
Categories: physics.atom-ph physics.optics
Comments: 4 pages, 4 figures, to be published in Phys. Rev. Lett
Subj-class: Atomic Physics; Optics
   We have demonstrated Zeeman slowing and capture of neutral Ra-225 and Ra-226
atoms in a magneto-optical trap (MOT). The intercombination transition 1S0-3P1
is the only quasi-cycling transition in radium and was used for laser-cooling
and trapping. Repumping along the 3D1-1P1 transition extended the lifetime of
the trap from milliseconds to seconds. Room-temperature blackbody radiation was
demonstrated to provide repumping from the metastable 3P0 level. We measured
the isotope shift and hyperfine splittings on the 3D1-1P1 transition with the
laser-cooled atoms, and set a limit on the lifetime of the 3D1 level based on
the measured blackbody repumping rate. Laser-cooled and trapped radium is an
attractive system for studying fundamental symmetries.
\\ ( , 904kb)
Paper: cond-mat/0701590
Date: Wed, 24 Jan 2007 11:58:09 GMT (14kb)

Title: Critical properties and Bose Einstein Condensation in dimer spin systems
Authors: E. Orignac, R. Citro, T. Giamarchi
Categories: cond-mat.str-el cond-mat.other
Comments: 4 pages, RevTeX 4, 3 EPS figures
Subj-class: Strongly Correlated Electrons; Other
   We analyze the spin relaxation time $1/T_1$ for a system made of weakly
coupled one dimensional ladders.This system allows to probe the dimensional
crossover between a Luttinger liquid and a Bose-Einstein condensateof magnons.
We obtain the temperature dependence of $1/T_1$ in the various dimensional
regimes, and discuss the experimental consequences.
\\ ( , 14kb)
Paper: quant-ph/0701172
Date: Tue, 23 Jan 2007 21:06:00 GMT (74kb)

Title: Initializing a Quantum Register from Mott Insulator States in Optical
Authors: Chuanwei Zhang, V.W. Scarola, and S. Das Sarma
Categories: quant-ph
Comments: 5 pages, 3 figures
   We propose and quantitatively develop two schemes to quickly and accurately
generate a stable initial configuration of neutral atoms in optical microtraps
by extraction from the Mott insulator state in optical lattices. We show that
thousands of atoms may be extracted and stored in the ground states of optical
microtrap arrays with one atom per trap in one operational process
demonstrating massive scalability. The failure probability during extraction in
the first scheme can be made sufficiently small ($\sim 10^{-4}$)to initialize a
large scale quantum register with high fidelity. A complementary faster scheme
with more extracted atoms but lower fidelity is also developed.
\\ ( , 74kb)
Paper: physics/0701272
Date: Tue, 23 Jan 2007 23:52:57 GMT (326kb)

Title: Experimental single-impulse magnetic focusing of launched cold atoms
Authors: David A. Smith, Aidan S. Arnold, Matthew J. Pritchard and Ifan G.
Categories: physics.atom-ph physics.optics
Comments: 10 pages, 4 figures
Subj-class: Atomic Physics; Optics
   Three-dimensional magnetic focusing of cold atoms with a single magnetic
impulse has been observed for the first time. We load 7x10^7 85-Rb atoms into a
magneto-optical trap, precool the atoms with optical molasses, then use moving
molasses to launch them vertically through 20.5cm to the apex of flight. In
transit the atoms are optically pumped, prior to the single magnetic lens
impulse that occurs 16.5cm above the MOT. Fluorescence images at the apex of
flight characterise the widths of the focussed cloud. Results were obtained for
four different configurations of the baseball lens, which tuned the
relationship between the axial and radial frequencies of the lens. Compact
focused clouds were seen for all four configurations.
\\ ( , 326kb)
Paper: cond-mat/0701616
Date: Thu, 25 Jan 2007 14:29:28 GMT (131kb)

Title: Transition from a two-dimensional superfluid to a one-dimensional Mott
Authors: Sara Bergkvist, Robert Saers, Emil Lundh, Anders Rosengren, Magnus
   Rehn, Anders Kastberg
Categories: cond-mat.other
Comments: 4 pages, 4 figures
Subj-class: Other
   A two-dimensional system of atoms in an anisotropic optical lattice is
studied theoretically. If the system is finite in one direction, it is shown to
exhibit a transition between a two-dimensional superfluid and a one-dimensional
Mott insulating chain of superfluid tubes. Monte Carlo simulations are
consistent with the expectation that the phase transition is of
Kosterlitz-Thouless type. The effect of the transition on experimental
time-of-flight images is discussed.
\\ ( , 131kb)
Paper: quant-ph/0701182
Date: Thu, 25 Jan 2007 17:07:07 GMT (68kb)

Title: Generation of EPR-entangled radiation through an atomic reservoir
Authors: Susanne Pielawa, Giovanna Morigi, David Vitali, Luiz Davidovich
Categories: quant-ph
Comments: 4 pages, 3 figures
   We propose a scheme for generating two-mode squeezing in high-Q resonators
using a beam of atoms with random arrival times. The scheme requires a
classical field driving transversally the atoms inside the cavity. The field
saturates the dipole transition and thereby sets it on resonance with two
non-degenerate cavity modes. The atomic beam pumps the cavity through
single-photon processes and acts like a spin reservoir, which attracts the
cavity field to the desired non-classical state, independently of the initial
state of the field. At steady state the cavity modes are in a two-mode squeezed
state, i.e., an Einstein-Podolski-Rosen (EPR) state, whose degree of
entanglement is controlled by the intensity and the frequency of the transverse
field. This scheme is robust against stochastic fluctuations in the atomic
beam, does not require atomic detection nor velocity selection, and can be
realized by presently available experimental setups with microwave resonators.
\\ ( , 68kb)
Paper: physics/0701297
Date: Thu, 25 Jan 2007 16:10:22 GMT (858kb)

Title: All-Optical Delay of Images using Slow Light
Authors: Ryan M. Camacho, Curtis J. Broadbent, Irfan Ali-Khan, and John C.
Categories: physics.optics physics.atom-ph
Comments: 4 pages, 5 figures
Subj-class: Optics; Atomic Physics
Journal-ref: PRL 98, 043902 (2007)
   Two-dimensional images carried by optical pulses (2 ns) are delayed by up to
10 ns in a 10 cm cesium vapor cell. By interfering the delayed images with a
local oscillator, the transverse phase and amplitude profiles of the images are
shown to be preserved. It is further shown that delayed images can be well
preserved even at very low light levels, where each pulse contains on average
less than one photon.
\\ ( , 858kb)


Paper: cond-mat/0611376
replaced with revised version Fri, 19 Jan 2007 16:23:15 GMT (29kb)

Title: The angular momentum of a magnetically trapped atomic condensate
Authors: P. Zhang, H. H. Jen, C. P. Sun and L. You
Categories: cond-mat.other
Comments: 4 pages, 1 figures
Subj-class: Other
Journal-ref: Phys. Rev. Lett. 98, 030403 (2007)
\\ ( , 29kb)
Paper: quant-ph/0610225
replaced with revised version Fri, 19 Jan 2007 16:19:19 GMT (45kb)

Title: Geometric phase of an atom in a magnetic storage ring
Authors: P. Zhang and L. You
Categories: quant-ph cond-mat.other
Comments: 7pages, 4 figures
Subj-class: Quantum Physics; Other
Journal-ref: Phys. Rev. A 74, 062110 (2006)
\\ ( , 45kb)
Paper: cond-mat/0606672
replaced with revised version Sat, 20 Jan 2007 15:51:18 GMT (16kb)

Title: Shot noise of interference between independent atomic systems
Authors: Anatoli Polkovnikov
Categories: cond-mat.stat-mech cond-mat.dis-nn
Comments: 5 pages, 1 figure, slightly expanded version with added
   clarifications and updated references
Subj-class: Statistical Mechanics; Disordered Systems and Neural Networks
\\ ( , 16kb)
Paper: physics/0604079
replaced with revised version Sun, 21 Jan 2007 10:56:44 GMT (694kb)

Title: Magnetic trapping of buffer-gas cooled chromium atoms and prospects for
   the extension to paramagnetic molecules
Authors: Joost M. Bakker, Michael Stoll, Dennis R. Weise, Oliver Vogelsang,
   Gerard Meijer, and Achim Peters
Categories: physics.atom-ph
Comments: 9 pages, 4 Figures
Subj-class: Atomic Physics
Journal-ref: J. Phys. B: At. Mol. Opt. Phys. 39, S1111-S1123, 2006
\\ ( , 694kb)
Paper: cond-mat/0505598
replaced with revised version Tue, 23 Jan 2007 12:50:23 GMT (74kb)

Title: A renormalized Gross-Pitaevskii Theory and vortices in a strongly
   interacting Bose gas
Authors: Ch. Moseley, K. Ziegler
Categories: cond-mat.other
Comments: 13 pages, 5 figures; revision and extension, figure 2 added
Subj-class: Other
\\ ( , 74kb)
Paper: cond-mat/0509118
replaced with revised version Tue, 23 Jan 2007 02:08:32 GMT (109kb)

Title: The BCS-Bose Crossover Theory
Authors: S.K. Adhikari, M. de Llano, F.J. Sevilla, M.A. Solis and J.J. Valencia
Categories: cond-mat.supr-con
Comments: thirteen pages including two figures. Physica C (in press, 2007)
Subj-class: Superconductivity
\\ ( , 109kb)
Paper: cond-mat/0607803
replaced with revised version Tue, 23 Jan 2007 23:50:52 GMT (286kb)

Title: BEC-BCS crossover, phase transitions and phase separation in polarized
   resonantly-paired superfluids
Authors: Daniel E. Sheehy, Leo Radzihovsky (University of Colorado)
Categories: cond-mat.supr-con
Comments: 76 RevTeX pages, 54 figures. Corrected typos. PRB two-column format.
   To appear in Annals of Physics (already available online at AOP website)
Subj-class: Superconductivity
\\ ( , 286kb)
Paper: cond-mat/0701251
replaced with revised version Wed, 24 Jan 2007 15:35:57 GMT (44kb)

Title: The Shear Viscosity to Entropy Density Ratio of Trapped Fermions in the
   Unitarity Limit
Authors: Thomas Schaefer (North Carolina State University)
Categories: cond-mat.other hep-ph nucl-th
Comments: 4 pages, two figures, minor revisions
Subj-class: Other
\\ ( , 44kb)
Paper: cond-mat/0607412
replaced with revised version Thu, 25 Jan 2007 09:10:50 GMT (6kb)

Title: Bose-Einstein Condensation and Casimir Effect of Trapped Ideal Bose Gas
   in between two Slabs
Authors: Shyamal Biswas
Categories: cond-mat.stat-mech
Comments: 4 pages
Subj-class: Statistical Mechanics
Journal-ref: Eur. Phys. J. D (2007)
DOI: 10.1140/epjd/e2007-00007-y
\\ ( , 6kb)

Till next time,

Dr M. J. Davis,               Senior Lecturer in Physics
School of Physical Sciences,  email:
University of Queensland,     ph   : +61 7 334 69824
Brisbane, QLD 4072,           fax  : +61 7 336 51242
Matt's arXiv selection: weekly summary of cold-atom papers from
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Received on Fri Feb 02 2007 - 05:26:44 EST

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