# Matt's arXiv selection: week ending 11 January 2008.

From: Matthew Davis <mdavis_at_physics.uq.edu.au>
Date: Sat, 26 Jan 2008 13:08:37 +1000

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

This week there were 31 new preprints and 6 replacements:

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arXiv:0801.0600
Date: Thu, 3 Jan 2008 21:12:14 GMT (898kb,D)

Title: Addressable, spin-dependent sub-wavelength optical lattices with cold
atoms
Authors: A. J. Daley, G. Pupillo, W. Yi, P. Zoller
Categories: cond-mat.other
\\
lattices on a subwavelength scale, which can be used as a tool for local
the faster timescales and higher energy and temperature scales determined by
the shorter lattice spacing. For Alkaline Earth atoms with non-zero nuclear
spin these potentials can be made state dependent, and we give specific
examples for Yb atoms.
\\ ( http://arxiv.org/abs/0801.0600 , 898kb)
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arXiv:0801.0635
Date: Fri, 4 Jan 2008 07:24:46 GMT (127kb)

Title: Phase separation and collapse in Bose-Fermi mixtures with a Feshbach
resonance
Authors: F. M. Marchetti, C. Mathy, M. M. Parish, D. A. Huse
Categories: cond-mat.other
\\
We consider a mixture of single-component bosonic and fermionic atoms with an
interspecies interaction that is varied using a Feshbach resonance. By
performing a mean-field analysis of a two-channel model, which describes both
narrow and broad Feshbach resonances, we find an unexpectedly rich phase
diagram at zero temperature: Bose-condensed and non-Bose-condensed phases form
a variety of phase-separated states that are accompanied by both critical and
tricritical points. We discuss the implications of our results for the
experimentally observed collapse of Bose-Fermi mixtures on the attractive side
of the Feshbach resonance, and we make predictions for future experiments on
Bose-Fermi mixtures close to a Feshbach resonance.
\\ ( http://arxiv.org/abs/0801.0635 , 127kb)
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arXiv:0801.0636
Date: Fri, 4 Jan 2008 08:52:18 GMT (23kb)

Title: Fermions in Deep Optical Lattice under p-wave Feshbach Resonance
Authors: S.-K. Yip
Categories: cond-mat.other cond-mat.supr-con
\\
We investigate theoretically the energy levels of two identical Fermions in a
harmonic potential well under p-wave Feshbach resonance. The magnetic fields
needed to affect the energy levels differ strongly among the levels, and they
can be at values far from the free space resonant field.
\\ ( http://arxiv.org/abs/0801.0636 , 23kb)
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arXiv:0801.0656
Date: Fri, 4 Jan 2008 10:58:07 GMT (11kb)

Title: Thermal Lifshitz Force between Atom and Conductor with Small Density of
Carriers
Authors: L. P. Pitaevskii
Categories: cond-mat.other cond-mat.stat-mech
\\
A new theory describing the interaction between atoms and a conductor with
small densities of current carriers is presented. The theory takes into account
the penetration of the static component of the thermally fluctuating field in
the conductor and generalizes the Lifshitz theory in the presence of a spatial
dispersion. The equation obtained for the force describes the continuous
crossover between the Lifshitz results for dielectrics and metals.
\\ ( http://arxiv.org/abs/0801.0656 , 11kb)
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arXiv:0801.0723
Date: Fri, 4 Jan 2008 19:45:45 GMT (105kb)

Title: Quantum criticality of U(1) gauge theories with fermionic and bosonic
matter in two spatial dimensions
Authors: Ribhu K. Kaul and Subir Sachdev
Categories: cond-mat.str-el
\\
We consider relativistic U(1) gauge theories in 2+1 dimensions, with N_b
species of complex bosons and N_f species of Dirac fermions at finite
temperature. The quantum phase transition between the Higgs and Coulomb phases
is described by a conformal field theory (CFT). At large N_b and N_f, but for
arbitrary values of the ratio N_b/N_f, we present computations of various
critical exponents and universal amplitudes for these CFTs. We make contact
with the different spin-liquids, charge-liquids and deconfined critical points
of quantum magnets that these field theories describe. We compute physical
observables that may be measured in experiments or numerical simulations of
insulating and doped quantum magnets.
\\ ( http://arxiv.org/abs/0801.0723 , 105kb)
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arXiv:0801.0427 (*cross-listing*)
Date: Wed, 2 Jan 2008 16:44:30 GMT (13kb)

Title: Vortices and Spontaneous Symmetry Breaking in Rotating Bose Gases
Authors: Robert Seiringer
Categories: math-ph cond-mat.stat-mech math.MP
Comments: Plenary talk given at QMath10, Moeciu, Romania, September 10-15, 2007
\\
We present a rigorous proof of the appearance of quantized vortices in dilute
trapped Bose gases with repulsive two-body interactions subject to rotation,
which was obtained recently in joint work with Elliott Lieb. Starting from the
many-body Schroedinger equation, we show that the ground state of such gases
is, in a suitable limit, well described by the nonlinear Gross-Pitaevskii
equation. In the case of axially symmetric traps, our results show that the
appearance of quantized vortices causes spontaneous symmetry breaking in the
ground state.
\\ ( http://arxiv.org/abs/0801.0427 , 13kb)
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arXiv:0801.0610
Date: Thu, 3 Jan 2008 22:37:50 GMT (15kb)

Title: Bounding the Bogoliubov coefficients
Authors: Petarpa Boonserm (Victoria University of Wellington) and Matt Visser
(Victoria University of Wellington)
Categories: quant-ph
\\
While over the last century or more considerable effort has been put into the
problem of finding approximate solutions for wave equations in general, and
quantum mechanical problems in particular, it appears that as yet relatively
little work seems to have been put into the complementary problem of
establishing rigourous bounds on the exact solutions. We have in mind either
bounds on parametric amplification and the related quantum phenomenon of
particle production (as encoded in the Bogoliubov coefficients), or bounds on
transmission and reflection coefficients. Modifying and streamlining an
approach developed by one of the present authors [Phys. Rev. A 59 (1999)
427-438], we investigate this question by developing a formal but exact
solution for the appropriate second-order linear ODE in terms of a time-ordered
exponential of 2x2 matrices, then relating the Bogoliubov coefficients to
certain invariants of this matrix. By bounding the matrix in an appropriate
manner, we can thereby bound the Bogoliubov coefficients.
\\ ( http://arxiv.org/abs/0801.0610 , 15kb)
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arXiv:0801.0623
Date: Fri, 4 Jan 2008 16:33:14 GMT (95kb)

Title: Double wells, scalar fields and quantum phase transitions in ions traps
Authors: A. Retzker, R. Thompson, D. Segal and M.B. Plenio
Categories: quant-ph
\\
Since Hund's work on the ammonia molecule, the double well potential has
formed a key paradigm in physics. Its importance is further underlined by the
central role it plays in the Landau theory of phase transitions. Recently, the
study of entanglement properties of many-body systems has added a new angle to
the study of quantum phase transitions of discrete and continuous degrees of
freedom, i.e., spin and harmonic chains. Here we show that control of the
radial degree of freedom of trapped ion chains allows for the simulation of
linear and non-linear Klein-Gordon fields on a lattice, in which the parameters
of the lattice, the non-linearity and mass can be controlled at will. The
system may be driven through a phase transition creating a double well
potential between different configurations of the ion crystal. The dynamics of
the system are controllable, local properties are measurable and tunnelling in
the double well potential would be observable.
\\ ( http://arxiv.org/abs/0801.0623 , 95kb)
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arXiv:0801.0624
Date: Fri, 4 Jan 2008 02:52:22 GMT (265kb)

Title: One dimensional lattice of permanent magnetic microtraps for ultracold
atoms on an atom chip
Authors: Mandip Singh, Michael Volk, Alexander Akulshin, Andrei Sidorov,
Russell McLean and Peter Hannaford
Categories: physics.atom-ph
\\
We report on the loading and trapping of ultracold atoms in a one dimensional
permanent magnetic lattice of period 10 micron produced on an atom chip. The
grooved structure which generates the magnetic lattice potential is fabricated
on a silicon substrate and coated with a perpendicularly magnetized
multilayered TbGdFeCo/Cr film of effective thickness 960 nm. Ultracold atoms
are evaporatively cooled in a Z-wire magnetic trap and then adiabatically
transferred to the magnetic lattice potential by applying an appropriate bias
field. Under our experimental conditions trap frequencies of up to 90 kHz in
the magnetic lattice are measured and the atoms are trapped at a distance of
less than 5 micron from the surface with a measured lifetime of about 450 ms.
These results are important in the context of studies of quantum coherence of
neutral atoms in periodic magnetic potentials on an atom chip.
\\ ( http://arxiv.org/abs/0801.0624 , 265kb)
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arXiv:0801.0744
Date: Fri, 4 Jan 2008 21:04:42 GMT (19kb)

Title: Resonating plaquette phases in large spin cold atom systems
Authors: Cenke Xu and Congjun Wu
Categories: cond-mat.str-el cond-mat.stat-mech
\\
Large spin cold atom systems can exhibit novel magnetic properties which do
not appear in usual spin-1/2 systems. We investigate the SU(4) resonating
plaquette state in the three dimensional cubic optical lattice with spin-3/2
cold fermions. A novel gauge field formalism is constructed to describe the
Rokhsar-Kivelson type of Hamiltonian and a duality transformation is used to
study the phase diagram. Due to the proliferation of topological defects, the
system is generally gapped for the whole phase diagram of the quantum model,
which agrees with the recent numerical studies. A critical line is found for
the classical plaquette system, which also corresponds to a quantum many-body
wavefunction in a "plaquette liquid phase".
\\ ( http://arxiv.org/abs/0801.0744 , 19kb)
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arXiv:0801.0791
Date: Mon, 7 Jan 2008 05:06:14 GMT (26kb)

Title: Variational wavefunction study of the triangular lattice supersolid
Authors: Arnab Sen, Prasenjit Dutt, Kedar Damle, R. Moessner
Categories: cond-mat.stat-mech cond-mat.str-el
Comments: 4 pages, 2-column PRL format
\\
We present a variational wavefunction which explains the behaviour of the
supersolid state formed by hard-core bosons on the triangular lattice. The
wavefunction is a linear superposition of {\em only and all} configurations
minimising the repulsion between the bosons (which it thus implements as a hard
constraint). Its properties can be evaluated exactly--in particular, the
variational minimisation of the energy yields (i) the surprising and initially
controversial spontaneous density deviation from half-filling (ii) a
quantitatively accurate estimate of the corresponding density wave (solid)
order parameter.
\\ ( http://arxiv.org/abs/0801.0791 , 26kb)
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arXiv:0801.0888
Date: Sun, 6 Jan 2008 20:38:11 GMT (50kb)

Title: Orbital orderings and frustrations of $p$-band systems in optical
lattices
Authors: Congjun Wu
Categories: cond-mat.str-el cond-mat.stat-mech
\\
We investigate general structures of orbital exchange physics in the
Mott-insulating states of $p$-orbital systems in optical lattices. Various new
features of orderings and frustrations are analyzed in different lattices. In
particular, in the honeycomb lattice the $p$-orbital exchange physics is
described by a novel type quantum 120$^\circ$-model whose classical ground
states can be mapped into the fully packed loop model multiplied with a U(1)
degree of freedom. It exhibits strong orbital frustrations and is promising to
realize the orbital liquid state. Orbital exchanges and frustrations in the
$p$-orbital 3D cubic lattice are also discussed.
\\ ( http://arxiv.org/abs/0801.0888 , 50kb)
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arXiv:0801.0911
Date: Mon, 7 Jan 2008 07:25:39 GMT (61kb)

Title: Bold diagrammatic Monte Carlo: A generic technique for polaron (and
many-body?) problems
Authors: Nikolay Prokof'ev and Boris Svistunov
Categories: cond-mat.str-el
Comments: 15 pages, 15 figures, revtex4
\\
We develop a Monte Carlo scheme for sampling series of Feynman diagrams for
the proper self-energy which are self-consistently expressed in terms of
renormalized particle propagators. This approach is used to solve the problem
of a single spin-down fermion resonantly interacting with the Fermi gas of
spin-up particles. Though the original series based on bare propagators are
sign-alternating and divergent one can still determine the answer behind them
by using two strategies (separately or together): (i) using proper series
re-summation techniques, and (ii) introducing renormalized propagators which
are defined in terms of the simulated proper self-energy, i.e. making the
entire scheme self-consistent. Our solution is important for understanding the
phase diagram and properties of the BCS-BEC crossover in the strongly
imbalanced regime. On the technical side, we develop a generic sign-problem
tolerant method for exact numerical solution of polaron-type models, and,
possibly, of the interacting many-body Hamiltonians.
\\ ( http://arxiv.org/abs/0801.0911 , 61kb)
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arXiv:0801.0952
Date: Mon, 7 Jan 2008 11:59:11 GMT (70kb)

Title: Mott transition in bosonic systems: Insights from the variational
approach
Authors: Manuela Capello, Federico Becca, Michele Fabrizio, and Sandro Sorella
Categories: cond-mat.str-el
Comments: 12 pages and 19 figures. Related to arXiv:0705.2684
\\
We study the Mott transition occurring for bosonic Hubbard models in one,
two, and three spatial dimensions, by means of a variational wave function
benchmarked by Green's function Monte Carlo calculations. We show that a very
accurate variational wave function, constructed by applying a long-range
Jastrow factor to the non-interacting boson ground state, can describe the
superfluid-insulator transition in any dimensionality. Moreover, by mapping the
quantum averages over such a wave function into the the partition function of a
classical model, important insights into the insulating phase are uncovered.
Finally, the evidence in favor of anomalous scenarios for the Mott transition
in two dimensions are reported whenever additional long-range repulsive
interactions are added to the Hamiltonian.
\\ ( http://arxiv.org/abs/0801.0952 , 70kb)
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arXiv:0801.0966
Date: Mon, 7 Jan 2008 12:55:11 GMT (500kb)

Title: Universality of Many-Body States in Rotating Bose and Fermi Systems
Authors: M. Borgh, M. Koskinen, J. Christensson, M. Manninen, S. M. Reimann
Categories: cond-mat.mes-hall cond-mat.other
\\
We propose a universal transformation from a many-boson state to a
corresponding many-fermion state in the lowest Landau level approximation of
rotating many-body systems, inspired by the Laughlin wave function and by the
Jain composite-fermion construction. We employ the exact-diagonalization
technique for finding the many-body states. The overlap between the transformed
boson ground state and the true fermion ground state is calculated in order to
measure the quality of the transformation. For very small and high angular
momenta, the overlap is typically above 90%. For intermediate angular momenta,
mixing between states complicates the picture and leads to small ground-state
overlaps at some angular momenta.
\\ ( http://arxiv.org/abs/0801.0966 , 500kb)
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arXiv:0801.1015
Date: Mon, 7 Jan 2008 16:08:40 GMT (316kb)

Title: Density-density correlations of the ultra-cold Fermi gas in an optical
lattice
Authors: T. Paananen, T. K. Koponen, P. T\"orm\"a, and J. -P. Martikainen
Categories: cond-mat.other
\\
In this paper we study the density-density correlations of the two component
Fermi gas in optical lattices. Three different type of phases, the BCS-state
(Bardeen, Cooper, and Schieffer), the FFLO-state (Fulde, Ferrel, Larkin, and
Ovchinnikov), and BP (breach pair) state, are considered. We show how these
states differ in their density-density correlations. The density-density
correlations are calculated not only at zero temperature, but also at non-zero
temperatures paying particular attention to how much the finite temperature
effects might complicate the detection of different phases. Since
one-dimensional systems have been shown to be very promising candidates to
observe FFLO states, we apply our results also to the computation of
correlation signals in a one-dimensional lattice. We find that the
density-density correlations reveal important information about the structure
of the underlying order parameter as well as about the quasiparticle
dispersions.
\\ ( http://arxiv.org/abs/0801.1015 , 316kb)
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arXiv:0801.1090
Date: Mon, 7 Jan 2008 18:16:13 GMT (574kb)

Title: Tunneling dynamics of few bosons in a double well
Authors: Sascha Z\"ollner, Hans-Dieter Meyer, Peter Schmelcher
Categories: cond-mat.other
\\
We study few-boson tunneling in a one-dimensional double well. As we pass
from weak interactions to the fermionization limit, the Rabi oscillations first
give way to highly delayed pair tunneling (for medium coupling), whereas for
very strong correlations multi-band Rabi oscillations emerge. All this is
explained on the basis of the exact few-body spectrum and without recourse to
the conventional two-mode approximation. Two-body correlations are found
essential to the understanding of the different tunnel mechanisms. The
investigation is complemented by discussing the effect of skewing the double
well, which offers the possibility to access specific tunnel resonances
\\ ( http://arxiv.org/abs/0801.1090 , 574kb)
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arXiv:0801.0724 (*cross-listing*)
Date: Fri, 4 Jan 2008 19:40:01 GMT (695kb)

Title: Emergent physics: Fermi point scenario
Authors: G.E. Volovik
Categories: gr-qc cond-mat.str-el hep-ph
Comments: 15 pages, 7 figures, extended and modified version of
arXiv:0709.1258, draft for proceedings of Royal Society scientific discussion
meeting "Cosmology meets condensed matter" to be held on 28 January 2008 in
London
\\
The Fermi-point scenario of emergent gravity has the following consequences:
gravity emerges together with fermionic and bosonic matter; emergent fermionic
matter consists of massless Weyl fermions; emergent bosonic matter consists of
gauge fields; Lorentz symmetry persists well above the Planck energy;
space-time is naturally 4-dimensional; Universe is naturally flat; cosmological
constant is naturally small or zero; underlying physics is based on discrete
symmetries; quantum gravity' cannot be obtained by quantization of Einstein
equations; there is no contradiction between quantum mechanics and gravity;
etc.
\\ ( http://arxiv.org/abs/0801.0724 , 695kb)
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arXiv:0801.0881
Date: Sun, 6 Jan 2008 18:05:17 GMT (632kb)

Title: High-visibility multi-photon interference of Hanbury Brown - Twiss type
for classical light
Authors: I. N. Agafonov, M. V. Chekhova, T. Sh. Iskhakov, A. N. Penin
Categories: quant-ph
\\
Difference-phase (or Hanbury Brown - Twiss type) intensity interference of
classical light is considered in higher orders in the intensity. It is shown
that, while the visibility of sum-phase (NOON-type) interference for classical
sources drops with the order of interference, the visibility of
difference-phase interference has opposite behavior. For three-photon and
four-photon interference of two coherent sources, the visibility can be as high
as 81.8% and 94.4%, respectively. High-visibility three-photon and four-photon
interference of space-time and polarization types has been observed in
experiment, for both coherent and pseudo-thermal light.
\\ ( http://arxiv.org/abs/0801.0881 , 632kb)
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arXiv:0801.0932
Date: Mon, 7 Jan 2008 09:22:52 GMT (112kb)

Title: Optimum spin-squeezing in Bose-Einstein condensates with particle losses
Authors: Yun Li (LKB - Lhomond, ECNU), Yvan Castin (LKB - Lhomond), Alice
Sinatra (LKB - Lhomond)
Categories: quant-ph
Proxy: ccsd hal-00202464
\\
The problem of spin squeezing with a bimodal condensate in presence of
particle losses is solved analytically by the Monte Carlo wavefunction method.
We find the largest obtainable spin squeezing as a function of the one-body
loss rate, the two-body and three-body rate constants, and the s-wave
scattering length.
\\ ( http://arxiv.org/abs/0801.0932 , 112kb)
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arXiv:0801.0930
Date: Mon, 7 Jan 2008 09:16:44 GMT (25kb)

Title: Suppression of Nonlinear Interactions in Resonant Macroscopic Quantum
Devices : the Example of the Solid-State Ring Laser Gyroscope
Authors: Sylvain Schwartz (TRT), Fran\c{c}ois Gutty, Gilles Feugnet (TRT),
Philippe Bouyer (LCFIO), Jean-Paul Pocholle (TRT)
Categories: physics.optics
Proxy: ccsd hal-00202466
\\
We study the suppression of nonlinear interactions in resonant macroscopic
quantum devices in the case of the solid-state ring laser gyroscope. These
nonlinear interactions are tuned by vibrating the gain medium along the cavity
axis. Beat note occurrence under rotation provides a precise measurement of the
strength of nonlinear interactions, which turn out to vanish for some discrete
values of the amplitude of vibration. Our theoretical description, in very good
agreement with the measured data, suggests the use of a higher vibration
frequency to achieve quasi-ideal rotation sensing over a broad range of
rotation speeds. We finally underline the analogy between this device and some
other macroscopic quantum rotation sensors, such as ring-shaped superfluid
configurations, where nonlinear interactions could be tuned for example by the
use of magnetically-induced Feschbach resonance.
\\ ( http://arxiv.org/abs/0801.0930 , 25kb)
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arXiv:0801.1103
Date: Tue, 8 Jan 2008 01:01:51 GMT (123kb)

Title: Berry Phase Effect on Exciton Transport and Bose Einstein Condensate
Authors: Wang Yao, Qian Niu
Categories: cond-mat.mes-hall
\\
We show a gauge structure that naturally exists for excitons in
semiconductors. The resultant Berry phase effects on exciton center-of-mass
motion are discussed for long-lived spatially indirect excitons in coupled
quantum wells. Spin-dependent topological transport driven by mechanical and
statistical forces are predicted. For trapped exciton gas, the Berry phase
effect manifests as a spin-dependent revolving mechanism. When sufficiently
large number of excitons have condensed, a nonrotating Bose-Einstein condensate
may become unstable against vortex formation.
\\ ( http://arxiv.org/abs/0801.1103 , 123kb)
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arXiv:0801.1270
Date: Tue, 8 Jan 2008 16:26:51 GMT (674kb)

Title: Limits to the sensitivity of a low noise compact atomic gravimeter
Authors: J. Le Gou\"et (SYRTE), Tanja Mehlst\"aubler (PTB), Jaewan Kim,
S\'ebastien Merlet (SYRTE), Andre Clairon (SYRTE), Arnaud Landragin (SYRTE),
Franck Pereira Dos Santos (SYRTE)
Categories: physics.atom-ph
Proxy: ccsd hal-00203007
\\
A detailed analysis of the most relevant sources of phase noise in an atomic
interferometer is carried out, both theoretically and experimentally. Even a
short interrogation time of 100 ms allows our cold atom gravimeter to reach an
excellent short term sensitivity to acceleration of $1.4\times 10^{-8}$g at 1s.
This result relies on the combination of a low phase noise laser system,
efficient detection scheme and good shielding from vibrations. In particular,
we describe a simple and robust technique of vibration compensation, which is
based on correcting the interferometer signal by using the AC acceleration
signal measured by a low noise seismometer.
\\ ( http://arxiv.org/abs/0801.1270 , 674kb)
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arXiv:0801.1378
Date: Wed, 9 Jan 2008 09:25:32 GMT (609kb)

Title: Dressed matter waves
Authors: Andre Eckardt and Martin Holthaus
Categories: cond-mat.other
Comments: 9 pages, 4 figures, to be published in: J. Phys.: Conference Series
\\
We suggest to view ultracold atoms in a time-periodically shifted optical
lattice as a "dressed matter wave", analogous to a dressed atom in an
electromagnetic field. A possible effect lending support to this concept is a
transition of ultracold bosonic atoms from a superfluid to a Mott-insulating
state in response to appropriate "dressing" achieved through time-periodic
lattice modulation. In order to observe this effect in a laboratory experiment,
one has to identify conditions allowing for effectively adiabatic motion of a
many-body Floquet state.
\\ ( http://arxiv.org/abs/0801.1378 , 609kb)
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arXiv:0801.1387
Date: Wed, 9 Jan 2008 10:23:50 GMT (54kb)

Title: Stability of the homogeneous Bose-Einstein condensate at large gas
parameter
Authors: Abdulla Rakhimov, Chul Koo Kim, Sang-Hoon Kim, and Jae Hyung Yee
Categories: cond-mat.stat-mech
Comments: 9 pages, 3 figures, Revtex
\\
The properties of the uniform Bose gas is studied within the optimized
variational perturbation theory (Gaussian approximation) in a self-consistent
way. It is shown that the atomic BEC with a repulsive interaction becomes
unstable when the gas parameter gamma=rho a3 exceeds a critical value
gamma_{crit} ~ 0.01. The quantum corrections beyond the Bogoliubov-Popov
approximation to the energy density, chemical potential and pressure in powers
of gamma expansions are presented.
\\ ( http://arxiv.org/abs/0801.1387 , 54kb)
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arXiv:0801.1504
Date: Wed, 9 Jan 2008 20:58:39 GMT (313kb)

Title: Gap and Pseudogap of a Unitary Fermi Gas by Quantum Monte Carlo
Authors: A. Bulgac, J.E. Drut, P. Magierski, and G. Wlazlowski
Categories: cond-mat.stat-mech
\\
We present Monte Carlo calculations of the susceptibility of a homogeneous 3D
system of fermions in the unitary regime at finite temperatures. Our data
allows for the determination of the quasiparticle spectrum, which is accurately
parameterized by an effective mass, a mean field, and a gap, and we discuss the
temperature dependence of these parameters. These results show the presence of
a pseudogap for temperatures above the critical temperature, when the system
ceases to be superfluid. We also report on zero temperature extrapolations of
our data away from unitarity and we compare them with existing fixed-node
Quantum Monte Carlo calculations at zero temperature.
\\ ( http://arxiv.org/abs/0801.1504 , 313kb)
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arXiv:0801.0763 (*cross-listing*)
Date: Sat, 5 Jan 2008 00:05:20 GMT (446kb)

Title: The Energy of n Identical Bosons in a Finite Volume at O(L^{-7})
Authors: William Detmold and Martin J. Savage
Categories: hep-lat cond-mat.stat-mech nucl-th
Report-no: NT_at_UW-08-01
\\
The volume dependence of the ground-state energy of n identical bosons with
short-range interactions in a periodic spatial volume with sides of length L is
calculated at order L^{-7} in the large volume expansion. This result will
enable a refined determination of the pi^+ pi^+ pi^+ interaction from lattice
QCD calculations.
\\ ( http://arxiv.org/abs/0801.0763 , 446kb)
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arXiv:0801.1523
Date: Thu, 10 Jan 2008 18:58:12 GMT (270kb,D)

Title: Determination of the Equation of State of a Two-Component Fermi Gas at
Unitarity
Authors: Yong-il Shin
Categories: cond-mat.stat-mech
\\
We report on the measurement of the equation of state of a two-component
Fermi gas of $^6$Li atoms with resonant interactions. By analyzing the in situ
density distributions of a population-imbalanced Fermi mixture confined in a
harmonic trap, we determine the energy density of a resonantly interacting
Fermi gas as a function of the densities of the two components. The presence of
the non-interacting ideal Fermi gas in the outer region of the trapped sample
allows to measure the equation of state directly from the shape of the cloud
without any absolute calibration of particle density. From the density profiles
obtained at our lowest temperature, we estimate the zero-temperature equation
of state.
\\ ( http://arxiv.org/abs/0801.1523 , 270kb)
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arXiv:0801.1567
Date: Thu, 10 Jan 2008 09:36:23 GMT (140kb)

Title: Semifluxons in Superconductivity and Cold Atomic Gases
Authors: R. Walser, E. Goldobin, O. Crasser, D. Koelle, R. Kleiner and W. P.
Schleich
Categories: cond-mat.mes-hall cond-mat.supr-con
Comments: 15 pages (Latex), 6 color figures (eps)
\\
Josephson junctions and junction arrays are well studied devices in
superconductivity. With external magnetic fields one can modulate the phase in
a long junction and create traveling, solitonic waves of magnetic flux, called
fluxons. Today, it is also possible to device two different types of junctions:
depending on the sign of the critical current density, they are called 0- or
pi-junction. In turn, a 0-pi junction is formed by joining two of such
junctions. As a result, one obtains a pinned Josephson vortex of fractional
magnetic flux, at the 0-pi boundary. Here, we analyze this arrangement of
superconducting junctions in the context of an atomic bosonic quantum gas,
where two-state atoms in a double well trap are coupled in an analogous
fashion. There, an all-optical 0-pi Josephson junction is created by the phase
of a complex valued Rabi-frequency and we a derive a discrete four-mode model
for this situation, which qualitatively resembles a semifluxon.
\\ ( http://arxiv.org/abs/0801.1567 , 140kb)
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arXiv:0801.1570
Date: Thu, 10 Jan 2008 09:54:07 GMT (433kb)

Title: Coherent Delocalization of Atomic Wave Packets in Driven Lattice
Potentials
Authors: V.V. Ivanov, A. Alberti, M. Schioppo, G. Ferrari, M. Artoni, M. L.
Chiofalo, and G. M. Tino
Categories: physics.atom-ph physics.optics
\\
Atomic wave packets loaded into a phase-modulated vertical optical-lattice
potential exhibit a coherent delocalization dynamics arising from intraband
transitions among Wannier-Stark levels. Wannier-Stark intraband transitions are
here observed by monitoring the in situ wave-packet extent. By varying the
modulation frequency, we find resonances at integer multiples of the Bloch
frequency. The resonances show a Fourier-limited width for interrogation times
up to 2 s. This can also be used to determine the gravity acceleration with ppm
resolution.
\\ ( http://arxiv.org/abs/0801.1570 , 433kb)
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\\
arXiv:0801.1580
Date: Thu, 10 Jan 2008 11:49:51 GMT (366kb)

Title: Determination of the Newtonian Gravitational Constant Using Atom
Interferometry
Authors: G. Lamporesi, A. Bertoldi, L. Cacciapuoti, M. Prevedelli and G.M. Tino
Categories: physics.atom-ph
\\
We present a new measurement of the Newtonian gravitational constant G based
on cold atom interferometry. Freely falling samples of laser-cooled rubidium
atoms are used in a gravity gradiometer to probe the field generated by nearby
source masses. In addition to its potential sensitivity, this method is
intriguing as gravity is explored by a quantum system. We report a value of
G=6.667 10^{-11} m^{3} kg^{-1} s^{-2}, estimating a statistical uncertainty of
$\pm$ 0.011 10^{-11} m^{3} kg^{-1} s^{-2} and a systematic uncertainty of $\pm$
0.003 10^{-11} m^{3} kg^{-1} s^{-2}. The long-term stability of the instrument
and the signal-to-noise ratio demonstrated here open interesting perspectives
for pushing the measurement accuracy below the 100 ppm level.
\\ ( http://arxiv.org/abs/0801.1580 , 366kb)
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The replacements:

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\\
arXiv:cond-mat/0612592
replaced with revised version Fri, 4 Jan 2008 11:46:15 GMT (33kb)

Title: Wigner Crystallization in Rapidly Rotating 2D Dipolar Fermi Gases
Authors: M.A. Baranov, H. Fehrmann, and M. Lewenstein
Categories: cond-mat.mes-hall
\\ ( http://arxiv.org/abs/cond-mat/0612592 , 33kb)
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\\
arXiv:0706.3378
replaced with revised version Fri, 4 Jan 2008 22:34:28 GMT (775kb)

Title: Many-body protected entanglement generation in interacting spin systems
Authors: A. M. Rey, L. Jiang, M. Fleischhauer, E. Demler and M.D. Lukin
Categories: cond-mat.other
Comments: 11 pages, 7 figures. This paper is a longer version of the paper
cond-mat/0703108
\\ ( http://arxiv.org/abs/0706.3378 , 775kb)
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\\
arXiv:0710.5099 (*cross-listing*)
replaced with revised version Mon, 7 Jan 2008 16:36:01 GMT (391kb)

Title: Creation of resilient entangled states and a resource for
measurement-based quantum computation with optical superlattices
Authors: B. Vaucher, A. Nunnenkamp, and D. Jaksch
Categories: cond-mat.other quant-ph
Comments: 23 pages, 6 figures, IOP style, to appear in New Journal of Physics
\\ ( http://arxiv.org/abs/0710.5099 , 391kb)
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\\
arXiv:cond-mat/0612133
replaced with revised version Tue, 8 Jan 2008 07:00:48 GMT (79kb)

Title: Density-density correlation and interference mechanism for two initially
independent Bose-Einstein condensates
Authors: Shujuan Liu, Hongwei Xiong
Categories: cond-mat.stat-mech
Journal-ref: New J. Phys. 9, 412 (2007)
\\ ( http://arxiv.org/abs/cond-mat/0612133 , 79kb)
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\\
arXiv:0709.0817
replaced with revised version Tue, 8 Jan 2008 10:38:22 GMT (21kb)

Title: Competition between final-state and pairing-gap effects in the
radio-frequency spectra of ultracold Fermi atoms
Authors: A. Perali, P. Pieri, G.C. Strinati
Categories: cond-mat.supr-con cond-mat.other
Comments: 4 pages, 3 figures, final version published in Phys. Rev. Lett
Journal-ref: Phys. Rev. Lett. 100, 010402 (2008)
DOI: 10.1103/PhysRevLett.100.010402
\\ ( http://arxiv.org/abs/0709.0817 , 21kb)
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\\
arXiv:0712.1482
replaced with revised version Wed, 9 Jan 2008 08:15:25 GMT (701kb)

Title: Guided atom laser : a new tool for guided atom optics
Authors: J. Billy (LCFIO), V. Josse (LCFIO), Z. Zuo (LCFIO), W. Guerin (LCFIO,
Inln), A. Aspect (LCFIO), Philippe Bouyer (LCFIO)
Categories: cond-mat.other
Proxy: ccsd hal-00195321
\\ ( http://arxiv.org/abs/0712.1482 , 701kb)
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Till next time,
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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Received on Fri Feb 01 2008 - 10:16:26 EST

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