Matt's arXiv selection: week ending December 15, 2006.

From: Matthew Davis <>
Date: Thu, 21 Dec 2006 13:19:11 +1000 (EST)

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

Hi all,

I'm going to take this opportunity to let you know about a workshop that may be
of interest:

"International Workshop on Quantum Noise" - celebrating Crispin Gardiner's
contributions to Quantum Optics and Atom Optics

14 - 18 MAY 2007
BreakFree Grand Pacific resort, Caloundra, Queensland, Australia.

The workshop will cover hot topics in quantum optics and ultracold quantum
gases, from both theory and experiment. A particular focus will be on quantum
aspects of matter waves and macroscopic quantum states, going beyond the methods
and predictions of mean-field theory. This will include advances in analytical
and computational methods, the latest experimental results probing the quantum
nature of BECs, and applications of BEC to quantum information.

Invited speakers: Brian Anderson, Rob Ballagh, Howard Carmichael, Subhash
Chaturvedi, Crispin Gardiner, Ed Hinds, Gerd Leuchs, Scott Parkins, Silvania
Pereira (tbc), Chris Westbrook, Peter Zoller (tbc)

There is a poster on the website if you wouldn't mind advertising it...

Not so many abstracts this week, only 16:

Paper: cond-mat/0612213
Date: Fri, 8 Dec 2006 12:11:23 GMT (533kb)

Title: Time-Averaged Adiabatic Potentials: Versatile traps and waveguides for
   ultracold quantum gases
Authors: Igor Lesanovsky and Wolf von Klitzing
Comments: 5 pages, 3 figures
Subj-class: Other
   We demonstrate a novel class of trapping potentials, time-averaged adiabatic
potentials (TAAP) which allows the generation of a large variety of traps and
waveguides for ultracold atoms. Multiple traps can be coupled through
controllable tunneling barriers or merged altogether. We present analytical
expressions for pancake-, cigar-, and ring- shaped traps. The ring-geometry is
of particular interest for guided matter-wave interferometry as it provides a
perfectly smooth waveguide of controllable diameter, and thus a tunable
sensitivity of the interferometer.
\\ ( , 533kb)
Paper: cond-mat/0612218
Date: Fri, 8 Dec 2006 18:02:37 GMT (616kb)

Title: Dark soliton dynamics in Bose-Einstein condensates at finite temperature
Authors: B. Jackson, N. P. Proukakis, and C. F. Barenghi
Comments: 4 pages, 4 figures
Subj-class: Statistical Mechanics
   The dynamics of a dark soliton in an elongated Bose-Einstein condensate at
finite temperatures is studied using numerical simulations. We find that in the
presence of harmonic confinement the soliton may oscillate even at finite
temperatures, but with an amplitude that increases with time, indicating the
decay of the soliton. The timescale of this decay decreases both with
increasing temperature and with increasing initial soliton velocity.
Simulations performed for the experiment of S. Burger et al., Phys. Rev. Lett.
83, 5198 (1999), reveal excellent agreement with the observed soliton decay,
confirming the crucial role of the thermal cloud in soliton dynamics.
\\ ( , 616kb)
Paper: quant-ph/0612057
Date: Thu, 7 Dec 2006 22:49:29 GMT (527kb)

Title: Mesoscopic entanglement of atomic ensembles through non-resonant
   stimulated Raman scattering
Authors: Wenhai Ji, Chunbai Wu, S.J. van Enk, M.G. Raymer
Comments: 32 papges, 6 figures and 1 table
   We propose a scheme of generating and verifying mesoscopic-level entanglement
between two atomic ensembles using non-resonant stimulated Raman scattering.
Entanglement can be generated by direct detection or balanced homodyne
detection of the Stokes fields from the two cells, after they interfere on a
beam splitter. The entanglement of the collective atomic fields can be
transferred to the anti-Stokes fields in a readout process. By measuring the
operator moments of the anti-Stokes fields, we can verify the presence of
entanglement. We model the effects of practical factors such as Stokes field
detector quantum efficiency and additive thermal noise in the entanglement
generating process, and anti-Stokes field losses in the entanglement
verification process, and find achievable regimes in which entanglement can be
verified at the levels of tens to hundreds of atomic excitations in the
\\ ( , 527kb)
Paper: cond-mat/0612263
Date: Mon, 11 Dec 2006 16:20:29 GMT (529kb)

Title: Dissipative dynamics of atomic Hubbard models coupled to a phonon bath:
   Dark state cooling of atoms within a Bloch band of an optical lattice
Authors: A. Griessner, A. J. Daley, S. R. Clark, D. Jaksch, and P. Zoller
Categories: cond-mat
Comments: 18 Pages, 16 Figures, ReVTeX 4
Subj-class: Other
   We analyse a laser assisted sympathetic cooling scheme for atoms within the
lowest Bloch band of an optical lattice. This scheme borrows ideas from
sub-recoil laser cooling, implementing them in a new context in which the atoms
in the lattice are coupled to a BEC reservoir. In this scheme, excitation of
atoms between Bloch bands replaces the internal structure of atoms in normal
laser cooling, and spontaneous emission of photons is replaced by creation of
excitations in the BEC reservoir. We analyse the cooling process for many
bosons and fermions, and obtain possible temperatures corresponding to a small
fraction of the Bloch band width within our model. This system can be seen as a
novel realisation of a many-body open quantum system.
\\ ( , 529kb)
Paper: cond-mat/0612268
Date: Mon, 11 Dec 2006 20:49:22 GMT (51kb)

Title: Fermionic superfluidity: From high Tc superconductors to ultracold Fermi
Authors: Qijin Chen, Chih-Chun Chien, Yan He, and K. Levin
Categories: cond-mat.str-el cond-mat.supr-con
Comments: Invited talk at the 5th International Conference on Stripes --
   Stripes 2006, 4 pages, 4 figures
Subj-class: Strongly Correlated Electrons; Superconductivity
   We present a pairing fluctuation theory which self-consistently incorporates
finite momentum pair excitations in the context of BCS--Bose-Einstein
condensation (BEC) crossover, and we apply this theory to superfluidity in high
$T_c$ superconductors and ultracold Fermi gases. There are strong similarities
between Fermi gases in the unitary regime and high Tc superconductors. We
address key issues of common interest in both systems, e.g., the pseudogap,
although we focus more on the Fermi gases and recent experiments, e.g., the
phase diagram, evidence for a pseudogap, thermodynamic behavior, and effects of
population imbalance.
\\ ( , 51kb)
Paper: physics/0612097
Date: Mon, 11 Dec 2006 17:08:51 GMT (2753kb)

Title: Ultracold Neutral Plasmas
Authors: T. C. Killian, T. Pattard, T. Pohl and J. M. Rost
Comments: 89 pages, 54 images
Report-no: KL-06-01
Subj-class: Atomic Physics; Plasma Physics
   Ultracold neutral plasmas, formed by photoionizing laser-cooled atoms near
the ionization threshold, have electron temperatures in the 1-1000 kelvin range
and ion temperatures from tens of millikelvin to a few kelvin. They represent a
new frontier in the study of neutral plasmas, which traditionally deals with
much hotter systems, but they also blur the boundaries of plasma, atomic,
condensed matter, and low temperature physics. Modelling these plasmas
challenges computational techniques and theories of non-equilibrium systems, so
the field has attracted great interest from the theoretical and computational
physics communities. By varying laser intensities and wavelengths it is
possible to accurately set the initial plasma density and energy, and
charged-particle-detection and optical diagnostics allow precise measurements
for comparison with theoretical predictions. Recent experiments using optical
probes demonstrated that ions in the plasma equilibrate in a strongly coupled
fluid phase. Strongly coupled plasmas, in which the electrical interaction
energy between charged particles exceeds the average kinetic energy, reverse
the traditional energy hierarchy underlying basic plasma concepts such as Debye
screening and hydrodynamics. Equilibration in this regime is of particular
interest because it involves the establishment of spatial correlations between
particles, and it connects to the physics of the interiors of gas-giant planets
and inertial confinement fusion devices.
\\ ( , 2392kb)
Paper: physics/0612089
Date: Sun, 10 Dec 2006 11:47:10 GMT (28kb)

Title: Full and partial reversed transitions in a vertical optical lattice
Authors: V. A. Kuz'menko
Comments: 3 pages LaTeX2e, 1 figure
Subj-class: Optics; General Physics
   Physical explanation of the origin of quantum resonances in a periodically
kicked Bose-Einstein condensate is proposed. It is based on the assumption of
inequality of the differential cross-sections of forward and partially reversed
optical transitions. For quantitative determination of such differences, we
propose to study the Bloch oscillations in a vertical optical lattice with
short pulses of laser radiation.
\\ ( , 28kb)
Paper: cond-mat/0612278
Date: Tue, 12 Dec 2006 08:12:12 GMT (244kb)

Title: Hanbury Brown Twiss effect for bosons versus fermions
Authors: Tom Jeltes (LASER CENTER VRIJE), John M. Mcnamara (LASER CENTER
   Valentina Krachmalnicoff (LCFIO), Martijn Schellekens (LCFIO), Aur\'{e}lien
   Perrin (LCFIO), Hong Chang (LCFIO), Denis Boiron (LCFIO), Alain Aspect
   (LCFIO), Christoph I. Westbrook (LCFIO)
Categories: cond-mat.other cond-mat.other
Comments: Submitted to Nature 15 Nov 2006
Proxy: ccsd hal-00119748
Subj-class: Other
   Fifty years ago, Hanbury Brown and Twiss (HBT) discovered photon bunching in
light emitted by a chaotic source, highlighting the importance of two-photon
correlations and stimulating the development of modern quantum optics . The
quantum interpretation of bunching relies upon the constructive interference
between amplitudes involving two indistinguishable photons, and its additive
character is intimately linked to the Bose nature of photons. Advances in atom
cooling and detection have led to the observation and full characterisation of
the atomic analogue of the HBT effect with bosonic atoms. By contrast, fermions
should reveal an antibunching effect, i.e., a tendency to avoid each other.
Antibunching of fermions is associated with destructive two-particle
interference and is related to the Pauli principle forbidding more than one
identical fermion to occupy the same quantum state. Here we report an
experimental comparison of the fermion and the boson HBT effects realised in
the same apparatus with two different isotopes of helium, 3He (a fermion) and
4He (a boson). Ordinary attractive or repulsive interactions between atoms are
negligible, and the contrasting bunching and antibunching behaviours can be
fully attributed to the different quantum statistics. Our result shows how
atom-atom correlation measurements can be used not only for revealing details
in the spatial density, or momentum correlations in an atomic ensemble, but
also to directly observe phase effects linked to the quantum statistics in a
many body system. It may thus find applications to study more exotic situations
\\ ( , 244kb)
Paper: physics/0612110
Date: Tue, 12 Dec 2006 17:44:27 GMT (90kb)

Title: Cancellation of the collisional frequency shift in caesium fountain
Authors: K. Szymaniec, W. Chalupczak, E. Tiesinga, C.J. Williams, S. Weyers, R.
Categories: physics.atom-ph
Subj-class: Atomic Physics
   We have observed that the collisional frequency shift in primary caesium
fountain clocks varies with the clock state population composition and, in
particular, is zero for a given fraction of the |F = 4, mF = 0> atoms,
depending on the initial cloud parameters. We present a theoretical model
explaining our observations. The possibility of the collisional shift
cancellation implies an improvement in the performance of caesium fountain
standards and a simplification in their operation. Our results also have
implications for test operation of fountains at multiple pi/2 pulse areas.
\\ ( , 90kb)
Paper: cond-mat/0612302
Date: Tue, 12 Dec 2006 21:00:05 GMT (92kb)

Title: Edge Current, Chern Number, and Transport in 2D Cold Atom Optical
   Lattices: Persistent Current in a Mott Insulator and Topological Invariants
   in a Kitaev Lattice
Authors: V.W. Scarola and S. Das Sarma
Categories: cond-mat.other
Subj-class: Other
   We theoretically study the observable response of edge currents in two
dimensional cold atom optical lattices. As an example we use Gutzwiller
mean-field theory to relate persistent edge currents surrounding a Mott
insulator in a slowly rotating trapped Bose-Hubbard system to time of flight
measurements. As an application, we briefly discuss the detection of Chern
number using edge currents of a topologically ordered optical lattice
\\ ( , 92kb)
Paper: cond-mat/0612324
Date: Wed, 13 Dec 2006 12:24:14 GMT (512kb)

Title: Lifetime of weakly-bound dimers of ultracold metastable helium studied
   by photoassociation
Authors: Steven Moal (LKB - Lhomond), Maximilien Portier (LKB - Lhomond),
   Nassim Zahzam (LKB - Lhomond), Mich\`{e}le Leduc (LKB - Lhomond)
Categories: cond-mat.other
Comments: 11 pages, 13 figures
Proxy: ccsd hal-00120114
Subj-class: Other
   We describe two-photon photoassociation (PA) experiments operated in an
ultracold gas of metastable $^4$He$^*$ atoms in the $2^3S_1$ state.
Atom-molecule dark resonances as well as Raman signals provide information on
the exotic molecule in the least bound vibrational J=2, $v=14$ state of the
$^5\Sigma_g^+$ interaction potential of two spin-polarized metastable atoms.
The physical origin of the various two-photon PA signals is first discussed.
Their linewidths are interpreted in term of processes limiting the lifetime
$\tau$ of the exotic molecule. A value of $\tau=1.4\pm0.3 \mu$s is found, which
is discussed in view of two recent calculations of the Penning ionization rate
induced by spin-dipole coupling and of the atom-molecule inelastic collisions.
\\ ( , 512kb)
Paper: physics/0612133
Date: Wed, 13 Dec 2006 17:11:39 GMT (305kb)

Title: Accumulation and thermalization of cold atoms in a finite-depth magnetic
Authors: R. Chicireanu, Q. Beaufils, A. Pouderous, B. Laburthe-Tolra, E.
   Marechal, J. V. Porto, L. Vernac, J. C. Keller, and O. Gorceix
Categories: physics.atom-ph
Comments: 9 pages, 10 Figures
Subj-class: Atomic Physics
   We experimentally and theoretically study the continuous accumulation of cold
atoms from a magneto-optical trap (MOT) into a finite depth trap, consisting in
a magnetic quadrupole trap dressed by a radiofrequency (RF) field. Chromium
atoms (52 isotope) in a MOT are continuously optically pumped by the MOT lasers
to metastable dark states. In presence of a RF field, the temperature of the
metastable atoms that remain magnetically trapped can be as low as 25 microK,
with a density of 10^17 atoms.m-3, resulting in an increase of the phase-space
density, still limited to 7.10^-6 by inelastic collisions. To investigate the
thermalization issues in the truncated trap, we measure the free evaporation
rate in the RF-truncated magnetic trap, and deduce the average elastic cross
section for atoms in the 5D4 metastable states, equal to 7.0 10^-16m2.
\\ ( , 305kb)
Paper: cond-mat/0612342
Date: Wed, 13 Dec 2006 22:03:49 GMT (851kb)

Title: Excitations of Few-Boson Systems in 1-D Harmonic and Double Wells
Authors: Sascha Z\"ollner, Hans-Dieter Meyer, and Peter Schmelcher
Categories: cond-mat.other
Comments: 11 pages, 10 figures
Subj-class: Other
   We examine the lowest excitations of one-dimensional few-boson systems
trapped in double wells of variable barrier height. Based on a numerically
exact multi-configurational method, we follow the whole pathway from the
non-interacting to the fermionization limit. It is shown how, in a purely
harmonic trap, the initially equidistant, degenerate levels are split up due to
interactions, but merge again for strong enough coupling. In a double well, the
low-lying spectrum is largely rearranged in the course of fermionization,
exhibiting level adhesion and (anti-)crossings. The evolution of the underlying
states is explained in analogy to the ground-state behavior. Our discussion is
complemented by illuminating the crossover from a single to a double well.
\\ ( , 851kb)
Paper: cond-mat/0612361
Date: Thu, 14 Dec 2006 13:27:51 GMT (65kb)

Title: Coupling of hydrodynamics and quasiparticle motion in collective modes
   of superfluid trapped Fermi gases
Authors: Michael Urban (IPNO)
Categories: cond-mat.other
Comments: 14 pages
Proxy: ccsd in2p3-00120317
Subj-class: Other
   At finite temperature, the hydrodynamic collective modes of superfluid
trapped Fermi gases are coupled to the motion of the normal component, which in
the BCS limit behaves like a collisionless normal Fermi gas. The coupling
between the superfluid and the normal components is treated in the framework of
a semiclassical transport theory for the quasiparticle distribution function,
combined with a hydrodynamic equation for the collective motion of the
superfluid component. We develop a numerical test-particle method for solving
these equations in the linear response regime. As a first application we study
the temperature dependence of the collective quadrupole mode of a Fermi gas in
a spherical trap. The coupling between the superfluid collective motion and the
quasiparticles leads to a rather strong damping of the hydrodynamic mode
already at very low temperatures. At higher temperatures the spectrum has a
two-peak structure, the second peak corresponding to the quadrupole mode in the
normal phase.
\\ ( , 65kb)
Paper: cond-mat/0612370
Date: Thu, 14 Dec 2006 18:16:04 GMT (327kb)

Title: Quantum switches and quantum memories for matter-wave lattice solitons
Authors: V. Ahufinger, A. Mebrahtu, R. Corbalan and A. Sanpera
Categories: cond-mat.other
Subj-class: Other
   We study the possibility of implementing a quantum switch and a quantum
memory for matter wave lattice solitons by making them interact with
"effective" potentials (barrier/well) corresponding to defects of the optical
lattice. In the case of interaction with an "effective" potential barrier, the
bright lattice soliton experiences an abrupt transition from complete
transmission to complete reflection (quantum switch) for a critical height of
the barrier. The trapping of the soliton in an "effective" potential well and
its release on demand, without loses, shows the feasibility of using the system
as a quantum memory. The inclusion of defects as a way of controlling the
interactions between two solitons is also reported.
\\ ( , 327kb)
Paper: physics/0612143
Date: Thu, 14 Dec 2006 16:12:37 GMT (131kb)

Title: Dynamical interferences as a probe of short-pulse-photoassociated
   rubidium dimer
Authors: Jordi Mur-Petit, Eliane Luc-Koenig, Francoise Masnou-Seeuws
Categories: physics.atom-ph
Comments: 4 pages, 4 figures
Subj-class: Atomic Physics
   We analyze the formation of Rb_2 molecules with short photoassociation pulses
applied to a cold Rb-85 sample. The laser field couples a continuum level of
the ground electronic state X ^1 Sigma_g^+ with bound levels in the
0_u^+(5S+5P_{1/2}) and 0_u^+(5S+5P_{3/2}) vibrational series. The non-adiabatic
coupling between the two excited channels induces time-dependent beatings in
the populations. We propose to take advantage of these oscillations either to
probe the photoassociation process via a photoionization pulse, or to optimize
the stabilization step into deep levels of the ground state.
\\ ( , 131kb)


Paper: cond-mat/0605603
replaced with revised version Fri, 8 Dec 2006 17:24:32 GMT (5kb)

Title: Finite time collapse of N classical fields described by coupled
   nonlinear Schrodinger equations
Authors: D. C. Roberts and A. C. Newell
Comments: v2: corrected typo on equation 1
Subj-class: Other; Mathematical Physics
Journal-ref: Phys. Rev. E 74, 047602 (2006)
\\ ( , 5kb)
Paper: cond-mat/0608542
replaced with revised version Fri, 8 Dec 2006 11:32:51 GMT (184kb)

Title: Three-boson recombination at ultralow temperatures
Authors: M.T. Yamashita, T. Frederico and Lauro Tomio
Comments: Published online in Physics Letters A
Subj-class: Soft Condensed Matter
Journal-ref: Physics Letters A (2006), doi:10.1016/j.physleta.2006.11.040
\\ ( , 184kb)
Paper: cond-mat/0606243
replaced with revised version Mon, 11 Dec 2006 15:44:24 GMT (84kb)

Title: Derivation of hydrodynamics for the gapless mode in the BEC-BCS
   crossover from the exact one-loop effective action
Authors: Da-Shin Lee, Chi-Yong Lin and Ray J. Rivers
Categories: cond-mat.other
Comments: Four pages, 1 figure. Whereas v.2 contained additional references,
   but was otherwise unchanged, this new version contains new material
   concerning our ability to provide a hydrodynamical description of the BEC/BSC
   system. This explains the change of title. Our old results are unaffected
Subj-class: Other
\\ ( , 84kb)
Paper: quant-ph/0606128
replaced with revised version Mon, 11 Dec 2006 13:32:25 GMT (230kb)

Title: How to observe a coherent superposition of an atom and a molecule
Authors: Mark R. Dowling, Stephen D. Bartlett, Terry Rudolph, and Robert W.
Comments: 17 pages, 1 figure, comments welcome, published version (minor
Subj-class: Quantum Physics; Other
Journal-ref: Phys. Rev. A, 74, 052113 (2006)
\\ ( , 230kb)
Paper: quant-ph/0609077
replaced with revised version Mon, 11 Dec 2006 15:50:19 GMT (36kb)

Title: An investigation into why macroscopic systems behave classically
Authors: David W. Hallwood, Keith Burnett, Jacob Dunningham
Comments: 23 preprint pages, 12 figures
\\ ( , 36kb)
Paper: cond-mat/0607433
replaced with revised version Tue, 12 Dec 2006 03:17:31 GMT (54kb)

Title: Coherent Collective Excitations in a Superfluid: Broken Symmetries and
Authors: S.J. Han
Categories: cond-mat.other
Comments: 53 pages and 1 figure
Subj-class: Other
\\ ( , 54kb)
Paper: physics/0608024
replaced with revised version Tue, 12 Dec 2006 07:58:25 GMT (486kb)

Title: Analysis of a Magnetically Trapped Atom Clock
Authors: D. Kadio and Y.B. Band
Categories: physics.atom-ph cond-mat.soft
Comments: 11 pages, 6 figures. Accepted for publication in Phys. Rev. A
Subj-class: Atomic Physics; Soft Condensed Matter
Journal-ref: Phys. Rev. A74, 053609 (2006)
DOI: 10.1103/PhysRevA.74.053609
\\ ( , 487kb)
Paper: cond-mat/0607127
replaced with revised version Tue, 12 Dec 2006 23:57:02 GMT (608kb)

Title: Spin Hall effects for cold atoms in a light induced gauge potential
Authors: Shi-Liang Zhu, Hao Fu, C.-J. Wu, S. -C. Zhang, and L. -M. Duan
Categories: cond-mat.mes-hall
Comments: 4 pages; The published version
Subj-class: Mesoscopic Systems and Quantum Hall Effect
Journal-ref: Phys. Rev. Lett. 97, 240401 (2006)
\\ ( , 608kb)
Paper: cond-mat/0607697
replaced with revised version Tue, 12 Dec 2006 22:21:22 GMT (570kb)

Title: Observation of Vortex Pinning in Bose-Einstein Condensates
Authors: S. Tung, V. Schweikhard, E. A. Cornell
Categories: cond-mat.other
Comments: 4 pages, 6 figures. Replaced by final version to appear in Phys. Rev.
Subj-class: Other
\\ ( , 570kb)
Paper: cond-mat/0609230
replaced with revised version Thu, 14 Dec 2006 12:37:19 GMT (213kb)

Title: Finite-temperature effects on the number fluctuation of ultracold atoms
   across the Superfluid to Mott-insulator transition
Authors: Xiancong Lu and Yue Yu
Categories: cond-mat.other
Comments: 7 pages,7 figures, final version for publication
Subj-class: Other
Journal-ref: Phys. Rev. A 74, 063615 (2006)
\\ ( , 213kb)

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
Legal stuff: Unless stated otherwise, this e-mail represents only the
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Received on Thu Dec 21 2006 - 13:19:11 EST

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