Matt's arXiv selection: week ending 2 May 2008.

From: Matthew Davis <>
Date: Thu, 08 May 2008 08:28:17 +1000

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

Hi all,

A rather quiet week with only 14 new preprints and 17 replacements:

Date: Thu, 24 Apr 2008 20:02:40 GMT (25kb)

Title: Adiabatic nonlinear probes of one-dimensional Bose gases
Authors: C. De Grandi, R. A. Barankov, A. Polkovnikov
Categories: cond-mat.other
Comments: 4+ pages, 4 figures
   We discuss two complementary problems: adiabatic loading of one-dimensional
bosons into an optical lattice and merging two one-dimensional Bose systems.
Both problems can be mapped to the sine-Gordon model. This mapping allows us to
find power-law scalings for the number of excitations with the ramping rate in
the regime where the conventional linear response approach fails. We show that
the exponent of this power law is sensitive to the interaction strength. In
particular, the response is larger, or less adiabatic, for strongly (weakly)
interacting bosons for the loading (merging) problem. Our results illustrate
that in general the nonlinear response to slow relevant perturbations can be a
powerful tool for characterizing properties of interacting systems.
\\ ( , 25kb)

Date: Thu, 24 Apr 2008 20:24:21 GMT (429kb,D)

Title: A Mott insulator of fermionic atoms in an optical lattice
Authors: Robert J\"ordens, Niels Strohmaier, Kenneth G\"unter, Henning Moritz,
   Tilman Esslinger
Categories: cond-mat.other cond-mat.str-el
   In a solid material strong interactions between the electrons can lead to
surprising properties. A prime example is the Mott insulator, where the
suppression of conductivity is a result of interactions and not the consequence
of a filled Bloch band. The proximity to the Mott insulating phase in fermionic
systems is the origin for many intriguing phenomena in condensed matter
physics, most notably high-temperature superconductivity. Therefore it is
highly desirable to use the novel experimental tools developed in atomic
physics to access this regime. Indeed, the Hubbard model, which encompasses the
essential physics of the Mott insulator, can be realised with quantum gases
trapped in an optical lattice. However, the Mott insulating regime has so far
been reached only with a gas of bosons, lacking the rich and peculiar nature of
fermions. Here we report on the formation of a Mott insulator of a repulsively
interacting two-component Fermi gas in an optical lattice. It is signalled by
three features: a drastic suppression of doubly occupied lattice sites, a
strong reduction of the compressibility inferred from the response of double
occupancy to atom number increase, and the appearance of a gapped mode in the
excitation spectrum. Direct control of the interaction strength allows us to
compare the Mott insulating and the non-interacting regime without changing
tunnel coupling or confinement. Our results pave the way for further studies of
the Mott insulator, including spin ordering and ultimately the question of
d-wave superfluidity.
\\ ( , 429kb)

arXiv:0804.3972 (*cross-listing*)
Date: Thu, 24 Apr 2008 17:15:16 GMT (14kb)

Title: Toward an AdS/cold atoms correspondence: a geometric realization of the
   Schroedinger symmetry
Authors: D.T. Son
Categories: hep-th cond-mat.other nucl-th
Comments: 14 pages
Report-no: INT PUB 08-08
   We discuss a realization of the nonrelativistic conformal group (the
Schroedinger group) as the symmetry of a spacetime. We write down a toy model
in which this geometry is a solution to field equations. We discuss various
issues related to nonrelativistic holography. In particular, we argue that free
fermions and fermions at unitarity correspond to the same bulk theory with
different choices for the near-boundary asymptotics corresponding to the source
and the expectation value of one operator. We describe an extended version of
nonrelativistic general coordinate invariance which is realized
\\ ( , 14kb)

Date: Fri, 25 Apr 2008 11:19:03 GMT (29kb)

Title: Causal signal transmission by quantum fields. I. Response of the
   harmonic oscillator
Authors: L.I. Plimak and S. Stenholm
Categories: quant-ph
Comments: Accepted to Annals of Physics
DOI: 10.1016/j.aop.2007.11.013
   It is shown that response properties of a quantum harmonic oscillator are in
essence those of a classical oscillator, and that, paradoxical as it may be,
these classical properties underlie all quantum dynamical properties of the
system. The results are extended to non-interacting bosonic fields, both
neutral and charged.
\\ ( , 29kb)
Date: Fri, 25 Apr 2008 12:06:34 GMT (39kb)

Title: Causal signal transmission by quantum fields. II. Quantum-statistical
   response of interacting bosons
Authors: L.I. Plimak and S. Stenholm
Categories: quant-ph
Comments: Accepted to Annals of Physics
DOI: 10.1016/j.aop.2007.11.014
   We analyse nonperturbatively signal transmission patterns in Green's
functions of interacting quantum fields. Quantum field theory is re-formulated
in terms of the nonlinear quantum-statistical response of the field. This
formulation applies equally to interacting relativistic fields and
nonrelativistic models. Of crucial importance is that all causality properties
to be expected of a response formulation indeed hold. Being by construction
equivalent to Schwinger's closed-time-loop formalism, this formulation is also
shown to be related naturally to both Kubo's linear response and Glauber's
macroscopic photodetection theories, being a unification of the two with
generalisation to the nonlinear quantum-statistical response problem. In this
paper we introduce response formulation of bosons; response reformulation of
fermions will be subject of a separate paper.
\\ ( , 39kb)

Date: Mon, 28 Apr 2008 18:51:20 GMT (25kb)

Title: Field theory of a quasi-one dimensional imbalanced Fermi gas
Authors: Erhai Zhao and W. Vincent Liu
Categories: cond-mat.other cond-mat.supr-con
   One-dimensional (1D) Fermi superfluid with finite population imbalance is a
quantum disordered version of the Fulde-Ferrel-Larkin-Ovchinnikov (FFLO) state
in higher dimensions. We show that this state violates spin-charge separation,
and its elementary excitations are fractional states carrying both charge and
spin. We construct the low energy effective field theory for this state from
the Bethe ansatz exact solution and generalize the theory to the study of a
lattice array of weakly coupled 1D-tubes of ultracold attractive Fermi gases
with spin imbalance. We obtain the phase diagram of such a quasi-1D system as
functions of density, population imbalance, and interaction strength. We also
estimate the transition temperature of the quasi-1D FFLO state.
\\ ( , 25kb)

Date: Tue, 29 Apr 2008 19:52:49 GMT (39kb)

Title: Andreev reflection in bosonic condensates
Authors: I. Zapata and F. Sols
Categories: cond-mat.other cond-mat.mes-hall cond-mat.supr-con
   We study the bosonic analog of Andreev reflection at a normal-superfluid
interface where the superfluid is a bosonic condensate. We model the normal
region as a zone where, due to the absence of interactions, nonlinear effects
can be neglected. For sufficiently reflecting interfaces, a stationary decaying
solution to the Gross-Pitaevskii equation does exist. Against the background of
a decaying condensate wave function, we find a novel contribution to the
current of reflected atoms. The group velocity of this Andreev reflected
component differs from that of the normally reflected one. For a
three-dimensional planar interface we find that Andreev reflection is neither
specular nor conjugate.
\\ ( , 39kb)

Date: Wed, 30 Apr 2008 10:53:55 GMT (380kb,D)

Title: High Resolution Imaging of Single Atoms in a Quantum Gas
Authors: Tatjana Gericke, Peter W\"urtz, Daniel Reitz, Tim Langen, and Herwig
Categories: cond-mat.other
Comments: 5 pages, 5 figures
   Our knowledge on ultracold quantum gases is strongly influenced by our
ability to probe these objects. In situ imaging combined with single atom
sensitivity is an especially appealing scenario as it can provide direct
information on the structure and the correlations of such systems. For a
precise characterization a high spatial resolution is mandatory. In particular,
the perspective to study quantum gases in optical lattices makes a resolution
well below one micrometer highly desirable. Here, we report on a novel
microscopy technique which is based on scanning electron microscopy and allows
for the detection of single atoms inside a quantum gas with a spatial
resolution of better than 150 nm. Imaging a Bose-Einstein condensate in a
one-dimensional optical lattice with 600 nm period we demonstrate single site
addressability in a sub-um optical lattice. The technique offers exciting
possibilities for the preparation, manipulation and analysis of quantum gases.
\\ ( , 380kb)
Date: Wed, 30 Apr 2008 09:23:42 GMT (80kb)

Title: Quantum motion effects in an ultracold-atom Mach-Zehnder interferometer
Authors: I. Lizuain, S. V. Mousavi, D. Seidel, J. G. Muga
Categories: quant-ph
Comments: 11 pages, 5 figures
   We study the effect of quantum motion in a Mach-Zehnder interferometer where
ultracold, two-level atoms cross a $\pi/2 $-$\pi $-$\pi/2$ configuration of
separated, laser illuminated regions. Explicit and exact expressions are
obtained for transmission amplitudes of monochromatic, incident atomic waves
using recurrence relations which take into account all possible paths: the
direct ones usually considered in the simple semiclassical treatment, but
including quantum motion corrections, and the paths in which the atoms are
repeatedly reflected at the fields.
\\ ( , 80kb)
Date: Wed, 30 Apr 2008 16:10:42 GMT (74kb)

Title: Interfacing light and single atoms with a lens
Authors: Meng Khoon Tey, Syed Abdullah Aljunid, Florian Huber, Brenda Chng,
   Zilong Chen, Gleb Maslennikov and Christian Kurtsiefer
Categories: quant-ph
Comments: 18 pages, 8 figures
   We investigate the interaction between a single atom and a light field in the
strong focusing regime. Such a configuration is subject to recent experimental
work not only with atoms but also molecules and other atom-like systems as
quantum dots. We derive the scattering probability for a photon from such a
microscopic object modeled by a two-level system, starting with a Gaussian beam
as the spatial mode of the light field. The focusing by an ideal lens is
modeled using spherical wave fronts of a field compatible with Maxwell
equations. Using a semi-classical approach for the atom-field interaction, we
predict scattering probability of photons by a single atom of up to 98% for
realistic focusing parameters. Experimental results for different focusing
strengths are compared with our theoretical model.
\\ ( , 74kb)
Date: Wed, 30 Apr 2008 23:11:34 GMT (689kb)

Title: Using photoemission spectroscopy to probe a strongly interacting Fermi
Authors: J. T. Stewart, J. P. Gaebler, and D. S. Jin
Categories: cond-mat.other
   Ultracold atom gases provide model systems in which many-body quantum physics
phenomena can be studied. Recent experiments on Fermi gases have realized a
phase transition to a Fermi superfluid state with strong interparticle
interactions. This system is a realization of the BCS-BEC crossover connecting
the physics of BCS superconductivity and that of Bose-Einstein condensation
(BEC). While many aspects of this system have been investigated, it has not yet
been possible to measure the single-particle excitation spectrum, which is a
fundamental property directly predicted by many-body theories. Here we show
that the single-particle spectral function of the strongly interacting Fermi
gas at T ~ Tc is dramatically altered in a way that is consistent with a large
pairing gap. We use photoemission spectroscopy to directly probe the elementary
excitations and energy dispersion in the Fermi gas of atoms. In these
photoemission experiments, an rf photon ejects an atom from our strongly
interacting system via a spin-flip transition to a weakly interacting state. We
measure the occupied single-particle density of states for an ultracold Fermi
gas of 40-potassium atoms at the cusp of the BCS-BEC crossover and on the BEC
side of the crossover, and compare these results to that for a nearly ideal
Fermi gas. Our results probe the many-body physics in a way that could be
compared to data for high-Tc superconductors. This new measurement technique
for ultracold atom gases, like photoemission spectroscopy for electronic
materials, directly probes low energy excitations and thus can reveal
excitation gaps and/or pseudogaps. Furthermore, this technique can provide an
analog to angle-resolved photoemission spectroscopy (ARPES) for probing
anisotropic systems, such as atoms in optical lattice potentials.
\\ ( , 689kb)
Date: Thu, 1 May 2008 15:27:50 GMT (154kb)

Title: Interference between Bose-Einstein condensates: quantum non-local
Authors: William W.J. Mullin (UMASS), Franck Lalo\"e (LKB - Lhomond)
Categories: quant-ph
Comments: version submitted to PRL
Proxy: ccsd hal-00276743
   In quantum mechanics, Fock states do not have a phase. When two or more
Bose-Einstein condensates are sent into interferometers, they nevertheless
acquire a relative phase under the effect of quantum measurements. The usual
explanation relies on spontaneous symmetry breaking: all probablilities can be
obtained by ascribing a phase to all condensates, and treating these variables
as completely unknown classical quantities. However, this image is not always
sufficient: when all particles are measured, quantum mechanics predicts
probabilities that are sometimes in contradiction with this image, as
illustrated by strong quantum violations of local realism. In this letter, we
show that interferometers can be constructed that demonstrate a large variety
of violations. With two independent condensates, we find violations of the
BCHSH inequalities, as well as new N-body Hardy impossibilities. With three
condensates, we obtain new GHZ (Greenberger, Horne and Zeilinger) type
contradictions. These violations are maintained for an arbitrary number of
\\ ( , 154kb)
Date: Thu, 1 May 2008 19:23:39 GMT (93kb)

Title: Numerical study of two-body correlation in a 1D lattice with perfect
Authors: B. Sun and F. Robicheaux
Categories: quant-ph
Journal-ref: New J. Phys. 10, 045032 (2008)
   We compute the dynamics of excitation and two-body correlation for two-level
"pseudoatoms" in a 1D lattice. We adopt a simplified model where pair
excitation within a finite range is perfectly blocked. Each superatom is
initially in the ground state, and then subjected to an external driving laser
with Rabi frequency satisfying a Poissonian distribution, mimicking the
scenario as in Rydberg gases. We find that two-body quantum correlation drops
very fast with the distance between pseudoatoms. However, the total correlation
decays slowly even at large distance. Our results may be useful to the
understanding of Rydberg gases in the strong blockade regime.
\\ ( , 93kb)
Date: Thu, 1 May 2008 01:43:44 GMT (45kb)

Title: Superradiant Raman scattering in an ultracold Bose gas at finite
Authors: H. Uys, P. Meystre
Categories: physics.atom-ph
Comments: 7 pages, 4 figures
   We study superradiant Raman scattering from an ultra-cold, but finite
temperature Bose gas in a harmonic trap. Numerical simulations indicate the
existence of distinct timescales associated with the decoherence of the
condensed versus thermal fractions, and the concomitant preferred scattering
from atoms in low lying trap states in the regime where superradiance takes
place on a timescale comparable to an inverse trap frequency. As a consequence
the scattered atoms experience a modest reduction in temperature as compared to
the unscattered atoms.
\\ ( , 45kb)

The replacements:

replaced with revised version Fri, 25 Apr 2008 09:28:38 GMT (181kb)

Title: Molecular formations in ultracold mixture of interacting and
   noninteracting atomic gases
Authors: T. Nishimura, A. Matsumoto, H. Yabu
Categories: cond-mat.soft cond-mat.other
Comments: 36 pages, 14 figures
\\ ( , 181kb)

arXiv:0803.0183 (*cross-listing*)
replaced with revised version Fri, 25 Apr 2008 12:25:21 GMT (316kb)

Title: Optimal control of atom transport for quantum gates in optical lattices
Authors: G. De Chiara, T. Calarco, M. Anderlini, S. Montangero, P. J. Lee, B.
   L. Brown, W. D. Phillips, and J. V. Porto
Categories: quant-ph cond-mat.other
Comments: revised version: minor changes, 2 references added, accepted for
   publication in Phys. Rev. A
\\ ( , 316kb)

replaced with revised version Fri, 25 Apr 2008 03:58:08 GMT (351kb)

Title: Rosen-Zener interferometry with Ultracold Atoms
Authors: Li-Bin Fu, Di-Fa Ye, Chaohong Lee, Weiping Zhang, and Jie Liu
Categories: cond-mat.mes-hall
Comments: 4 pages, 5 figures
\\ ( , 351kb)

replaced with revised version Sun, 27 Apr 2008 11:40:40 GMT (279kb)

Title: Exact Solution of Strongly Interacting Quasi-One-Dimensional Spinor Bose
Authors: Frank Deuretzbacher, Klaus Fredenhagen, Daniel Becker, Kai Bongs,
   Klaus Sengstock, Daniela Pfannkuche
Categories: cond-mat.other
Comments: Revised to discuss large but finite interactions
Journal-ref: Phys. Rev. Lett. 100, 160405 (2008)
DOI: 10.1103/PhysRevLett.100.160405
\\ ( , 279kb)

replaced with revised version Mon, 28 Apr 2008 16:35:41 GMT (155kb)

Title: Collisional stability of fermionic Feshbach molecules
Authors: J. J. Zirbel, K.-K. Ni, S. Ospelkaus, J. P. D'Incao, C. E. Wieman, J.
   Ye, and D. S. Jin
Categories: cond-mat.other
Comments: 4 pages, 4 figures, 1 table
DOI: 10.1103/PhysRevLett.100.143201
\\ ( , 155kb)

replaced with revised version Fri, 25 Apr 2008 20:35:07 GMT (10kb)

Title: Nonlinear Differential Equations for Correlation Functions of Fermi Gas
   in One Dimension
Authors: E. Bettelheim, A. G. Abanov, and P. Wiegmann
Categories: cond-mat.mes-hall
Comments: 5 pages
\\ ( , 10kb)

replaced with revised version Mon, 28 Apr 2008 15:39:12 GMT (284kb)

Title: Incommensurate superfluidity of bosons in a double-well optical lattice
Authors: Vladimir M. Stojanovic, Congjun Wu, W. Vincent Liu, S. Das Sarma
Categories: cond-mat.other quant-ph
Comments: 4 pages, 5 figures. References added, typos corrected
\\ ( , 284kb)

replaced with revised version Sat, 26 Apr 2008 13:47:16 GMT (192kb)

Title: Broadband optical delay with large dynamic range using atomic dispersion
Authors: M. R. Vanner, R. J. McLean, A. I. Sidorov, P. Hannaford and A. M.
Categories: physics.optics
Comments: 8 pages, 5 figures
Journal-ref: J. Phys. B: At. Mol. Opt. Phys. 41 051004 (2008)
\\ ( , 192kb)

replaced with revised version Tue, 29 Apr 2008 11:39:42 GMT (83kb)

Title: Dynamics and stability of Bose-Einstein condensates with attractive 1/r
Authors: Holger Cartarius, Toma\v{z} Fab\v{c}i\v{c}, J\"org Main, G\"unter
Categories: quant-ph nlin.CD
Comments: Corrected the original usage of two inconsistent energy units in some
   equations and in Figs. 2, 4, 5, and 6; 12 pages 12 figures
\\ ( , 83kb)

replaced with revised version Wed, 30 Apr 2008 15:27:56 GMT (856kb)

Title: Renormalization Group Theory for the Imbalanced Fermi Gas
Authors: K. B. Gubbels and H. T. C. Stoof
Categories: cond-mat.stat-mech cond-mat.supr-con
Comments: Replaced with published version
Journal-ref: Phys. Rev. Lett. 100, 140407 (2008)
\\ ( , 856kb)
replaced with revised version Wed, 30 Apr 2008 15:36:12 GMT (739kb)

Title: State-dependent, addressable subwavelength lattices with cold atoms
Authors: W. Yi, A. J. Daley, G. Pupillo, P. Zoller
Categories: cond-mat.other
Comments: replaced with a longer version. 23 pages, 11 figures
\\ ( , 739kb)
replaced with revised version Wed, 30 Apr 2008 13:17:36 GMT (276kb)

Title: Zero-Range Processes with Multiple Condensates: Statics and Dynamics
Authors: Yonathan Schwarzkopf, M. R. Evans and David Mukamel
Categories: cond-mat.stat-mech
Comments: 25 pages, 18 figures
Journal-ref: J. Phys. A: Math. Theor. 41 (2008) 205001
DOI: 10.1088/1751-8113/41/20/205001
\\ ( , 276kb)
replaced with revised version Wed, 30 Apr 2008 10:48:54 GMT (16kb)

Title: Landau levels on the 2D torus: a numerical approach
Authors: Enrico Onofri
Categories: quant-ph
Comments: 8 pages, 4 figures
\\ ( , 16kb)
replaced with revised version Thu, 1 May 2008 02:39:48 GMT (69kb)

Title: Coherent Collective Excitations in a Superfluid: Broken Symmetries and
Authors: S.J. Han
Categories: cond-mat.other
Comments: 82 pages, 1 figure
\\ ( , 69kb)
replaced with revised version Thu, 1 May 2008 15:45:23 GMT (149kb)

Title: How to fix a broken symmetry: Quantum dynamics of symmetry restoration
   in a ferromagnetic Bose-Einstein condensate
Authors: Bogdan Damski and Wojciech H. Zurek
Categories: cond-mat.other hep-th quant-ph
Comments: 15 pages, 11 figures, final version accepted in NJP (slight changes
   with respect to the former submission)
Report-no: LAUR-07-7540
Journal-ref: New J. Phys. 10, 045023 (2008)
\\ ( , 149kb)
replaced with revised version Thu, 1 May 2008 13:26:35 GMT (272kb)

Title: Disorder-induced trapping versus Anderson localization in Bose-Einstein
   condensates expanding in disordered potentials
Authors: Laurent Sanchez-Palencia (LCFIO), David Cl\'ement (LCFIO), Pierre
   Lugan (LCFIO), Philippe Bouyer (LCFIO), Alain Aspect (LCFIO)
Categories: cond-mat.other quant-ph
Comments: New Journal of Physics; focus issue "Quantum Correlations in Tailored
   Matter - Common perspectives of mesoscopic systems and quantum gases"; 30
   pages, 10 figures
Proxy: ccsd hal-00263549
Journal-ref: New Journal of Physics 10 (2008) 045019
DOI: 10.1088/1367-2630/10/4/045019
\\ ( , 272kb)
replaced with revised version Thu, 1 May 2008 02:41:14 GMT (0kb)

Title: Phase Separation in Bose-Fermi-Fermi Mixtures as a Probe of Fermi
Authors: S. G. Bhongale
Categories: cond-mat.stat-mech cond-mat.supr-con quant-ph
\\ ( , 0kb)

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 Thu May 08 2008 - 11:51:26 EST

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