# Matt's arXiv selection, Monday 22nd May 2006

From: Matthew Davis <mdavis_at_physics.uq.edu.au>
Date: Mon, 22 May 2006 18:04:39 +1000 (EST)

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

Hi all,

I've had a busy day today, and so the arXiv selection email was delayed until
now. However, you have the bonus that it includes the latest arXiv mailings as
posted a couple of hours ago.

On with the abstracts:

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Paper: quant-ph/0605098
Date: Thu, 11 May 2006 02:39:28 GMT (253kb)

Title: Deterministic single photons via conditional quantum evolution
Authors: D. N. Matsukevich, T. Chaneliere, S. D. Jenkins, S.-Y. Lan, T. A. B.
Kennedy, and A. Kuzmich
\\
A source of deterministic single photons is proposed and demonstrated by the
application of a measurement-based feedback protocol to a heralded single
photon source consisting of an ensemble of cold rubidium atoms. Our source is
stationary and produces a photoelectric detection record with sub-Poissonian
statistics.
\\ ( http://arXiv.org/abs/quant-ph/0605098 , 253kb)
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Paper: cond-mat/0605315
Date: Thu, 11 May 2006 20:57:40 GMT (73kb)

Title: Dipolar Bose-Einstein condensates with dipole-dependent scattering
length
Authors: Shai Ronen, Daniele C. E. Bortolotti, D. Blume, and John L. Bohn
Subj-class: Statistical Mechanics
\\
We consider a Bose-Einstein condensate of polar molecules in a harmonic trap,
where the effective dipole may be tuned by an external field. We demonstrate
that taking into account the dependence of the scattering length on the dipole
moment is essential to reproducing the correct energies and for predicting the
stability of the condensate. We do this by comparing Gross-Pitaevskii
calculations with diffusion Monte Carlo calculations. We find very good
agreement between the results obtained by these two approaches once the dipole
dependence of the scattering length is taken into account. We also examine the
behavior of the condensate in non-isotropic traps.
\\ ( http://arXiv.org/abs/cond-mat/0605315 , 73kb)
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Paper: cond-mat/0605335
Date: Fri, 12 May 2006 15:01:59 GMT (214kb)

Title: Ultracold polarized Fermi gas at intermediate temperatures
Authors: Jani-Petri Martikainen
Subj-class: Statistical Mechanics
\\
We consider the polarized two-component Fermi gas at non-zero temperatures.
We point out that stable polarized paired states which are more stable than
their phase separated counterparts with unpolarized superfluid region can exist
below the critical temperature. We also solve the system behavior in a trap
using the local density approximation and find gradually increasing
polarization in the center of the system as the temperature is increased.
However, in the strongly interacting region the central polarization increases
most rapidly close to the mean-field critical temperature, which is known to be
substantially higher than the critical temperature for superfluidity. This
indicates that most of the phase separation occurs in the fluctuation region
prior to superfluidity and that the polarization in the actual superfluid is
modest.
\\ ( http://arXiv.org/abs/cond-mat/0605335 , 214kb)
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Paper: cond-mat/0605343
Date: Fri, 12 May 2006 14:33:27 GMT (93kb)

Title: Composite fermion theory of rapidly rotating two-dimensional bosons
Authors: N. Regnault, C.C. Chang, Th. Jolicoeur, J.K. Jain
Comments: 12 pages, 9 figures. Conference proceeding. BEC 2005 Italy
Subj-class: Mesoscopic Systems and Quantum Hall Effect
Journal-ref: J. Phys. B: At. Mol. Opt. Phys. 39 (2006) S89-S99
DOI: 10.1088/0953-4075/39/10/S09
\\
Ultracold neutral bosons in a rapidly rotating atomic trap have been
predicted to exhibit fractional quantum Hall-like states. We describe how the
composite fermion theory, used in the description of the fractional quantum
Hall effect for electrons, can be applied to interacting bosons. Numerical
evidence supporting the formation of composite fermions, each being the bound
state of a boson and one flux quantum, is shown for filling fractions of the
type nu=p/(p+1), both by spectral analysis and by direct comparison with trial
wave functions. The rapidly rotating system of two-dimensional bosons thus
constitutes an interesting example of "statistical transmutation," with bosons
behaving like composite fermions. We also describe the difference between the
electronic and the bosonic cases when p approaches infinity. Residual
interactions between composite fermions are attractive in this limit, resulting
in a paired composite-fermion state described by the Moore-Read wave function.
\\ ( http://arXiv.org/abs/cond-mat/0605343 , 93kb)
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Paper: cond-mat/0506046
replaced with revised version Fri, 12 May 2006 00:09:49 GMT (174kb)

Title: Equation of state of a superfluid Fermi gas in the BCS-BEC crossover
Authors: Hui Hu, Xia-Ji Liu, and Peter D. Drummond
Comments: 7 pages, 4 figures, published version in Europhysics Letters, a long
preprint with details will appear soon
Subj-class: Superconductivity; Statistical Mechanics
Journal-ref: Europhys. Lett. 74, 574 (2006)
DOI: 10.1209/epl/i2006-10023-y
\\ ( http://arXiv.org/abs/cond-mat/0506046 , 174kb)
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Paper: cond-mat/0602483
replaced with revised version Fri, 12 May 2006 03:37:34 GMT (84kb)

Title: Ground state properties of one-dimensional ultracold Bose gases in a
hard-wall trap
Authors: Yajiang Hao, Yunbo Zhang, J.-Q. Liang and Shu Chen
Comments: 7 pages, 6 figures, typos corrected, version to be published in Phys.
Rev. A
Subj-class: Strongly Correlated Electrons
\\ ( http://arXiv.org/abs/cond-mat/0602483 , 84kb)
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Paper: quant-ph/0601137
replaced with revised version Fri, 12 May 2006 07:03:32 GMT (465kb)

Title: Theoretical study of a cold atom beam splitter
Authors: Naceur Gaaloul (PPM, LSAMA), Annick Suzor-Weiner (PPM), Laurence
Pruvost (LAC), Mourad Telmini (LSAMA), Eric Charron (PPM)
Proxy: ccsd ccsd-00017414
\\ ( http://arXiv.org/abs/quant-ph/0601137 , 465kb)
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Paper: cond-mat/0605350
Date: Fri, 12 May 2006 20:41:41 GMT (223kb)

Title: The Fermi-Hubbard model at unitarity
Authors: Evgeni Burovski, Nikolay Prokof'ev, Boris Svistunov and Matthias
Troyer
Comments: 27 pages, iopart class file. Submitted to New J. Phys
Subj-class: Superconductivity; Statistical Mechanics
\\
We simulate the dilute attractive Fermi-Hubbard model in the unitarity regime
using a diagrammatic determinant Monte Carlo algorithm with worm-type updates.
We obtain the dependence of the critical temperature on the filling factor
$\nu$ and, by extrapolating to $\nu \to 0$, determine the universal critical
temperature of the continuum unitary Fermi gas in units of Fermi energy:
$T_c/\epsilon_F=0.152(7)$. We also determine the thermodynamic functions and
show how the Monte Carlo results can be used for accurate thermometry of a
trapped unitary gas.
\\ ( http://arXiv.org/abs/cond-mat/0605350 , 223kb)
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Paper: cond-mat/0605351
Date: Mon, 15 May 2006 16:19:48 GMT (740kb)

Title: Spontaneous symmetry breaking in a quenched ferromagnetic spinor Bose
condensate
Authors: L. E. Sadler, J. M. Higbie, S. R. Leslie, M. Vengalattore and D. M.
Stamper-Kurn
Subj-class: Statistical Mechanics
\\
A central goal in condensed matter and modern atomic physics is the
exploration of many-body quantum phases and the universal characteristics of
quantum phase transitions in so far as they differ from those established for
thermal phase transitions. Compared with condensed-matter systems, atomic gases
are more precisely constructed and also provide the unique opportunity to
explore quantum dynamics far from equilibrium. Here we identify a second-order
quantum phase transition in a gaseous spinor Bose-Einstein condensate, a
quantum fluid in which superfluidity and magnetism, both associated with
symmetry breaking, are simultaneously realized. $^{87}$Rb spinor condensates
were rapidly quenched across this transition to a ferromagnetic state and
probed using in-situ magnetization imaging to observe spontaneous symmetry
breaking through the formation of spin textures, ferromagnetic domains and
domain walls. The observation of topological defects produced by this symmetry
breaking, identified as polar-core spin-vortices containing non-zero spin
current but no net mass current, represents the first phase-sensitive in-situ
detection of vortices in a gaseous superfluid.
\\ ( http://arXiv.org/abs/cond-mat/0605351 , 740kb)
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Paper: cond-mat/0605369
Date: Mon, 15 May 2006 07:38:51 GMT (477kb)

Title: Anisotropic Kosterlitz-Thouless Transition Induced by Hard-Wall
Boundaries
Authors: Gary A. Williams
Comments: 4 pages, 3 figures, submitted to PRB
Subj-class: Statistical Mechanics
\\
The spatial dependence of the superfluid density is calculated for the
Kosterlitz-Thouless transition in the presence of hard-wall boundaries, for the
case of a single wall bounding the half-infinite plane, and for a superfluid
strip bounded by two walls. The boundaries induce additional vortices that
cause the superfluid density to become anisotropic, with the tensor component
perpendicular to the wall falling to zero at the wall, whereas the component
parallel to the wall remains finite. The effects of the boundaries are found to
extend over all measured length scales, since the correlation length is
infinite in the superfluid phase.
\\ ( http://arXiv.org/abs/cond-mat/0605369 , 477kb)
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Paper: cond-mat/0605374
Date: Mon, 15 May 2006 09:49:58 GMT (600kb)

Title: Statics and dynamics of BEC's in double square well potentials
Authors: E. Infeld, P. Zi\'{n}, J. Goca{\l}ek and M. Trippenbach
Subj-class: Other
\\
In this paper we treat the behavior of Bose Einstein condensates in double
square well potentials, both of equal and different depths. For even depth,
symmetry preserving solutions to the relevant nonlinear Schr\"{o}dinger
equation is known, just as in the linear limit. When the nonlinearity is strong
enough, symmetry breaking solutions also exist, side by side with the symmetric
one. Interestingly, solutions almost entirely localized in one of the wells are
known as an extreme case. Here we outline a method for obtaining all these
solutions for repulsive interactions. The bifurcation point at which, for
critical nonlinearity, the asymmetric solutions branch off from the symmetry
preserving ones is found analytically. We also find this bifurcation point and
treat the solutions generally via a Josephson Junction model.
When the confining potential is in the form of two wells of different depth,
interesting new phenomena appear. This is true of both the occurrence of the
bifurcation point for the static solutions, and also of the dynamics of phase
and amplitude varying solutions. Again a generalization of the Josephson model
proves useful. The stability of solutions is treated briefly.
\\ ( http://arXiv.org/abs/cond-mat/0605374 , 600kb)
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Paper: cond-mat/0605388
Date: Mon, 15 May 2006 14:54:34 GMT (140kb)

Title: Transition from Free to Interacting Composite Fermions away from
$\nu$=1/3
Authors: Y. Gallais, T.H. Kirschenmann, I. Dujovne, C.F. Hirjibehedin, A.
Pinczuk, B.S. Dennis, L.N. Pfeiffer and K.W. West
Subj-class: Mesoscopic Systems and Quantum Hall Effect; Strongly Correlated
Electrons
\\
Spin excitations from a partially populated composite fermion level are
studied above and below $\nu=1/3$. In the range $2/7<\nu<2/5$ the experiments
uncover significant departures from the non-interacting composite fermion
picture that demonstrate the increasing impact of interactions as quasiparticle
Landau levels are filled. The observed onset of a transition from free to
interacting composite fermions could be linked to condensation into the higher
order states suggested by transport experiments and numerical evaluations
performed in the same filling factor range.
\\ ( http://arXiv.org/abs/cond-mat/0605388 , 140kb)
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Paper: quant-ph/0605114
Date: Sat, 13 May 2006 01:00:03 GMT (277kb)

Title: Reaching 7Li BEC with a Mini-Trap
Authors: Ruquan Wang, Mingchang Liu, Francesco Minardi and Mark Kasevich
\\
A novel mm-scale Ioffe-Pritchard trap is used to achieve Bose-Einstein
condensation in 7Li. The trap employs free-standing copper coils integrated
onto a direct-bond copper surface electrode structure. The trap achieves a
radial magnetic gradient of 420 G/cm, an axial oscillation frequency of 50 Hz
and a trap depth of 66 G with a 100 A drive current and 7 W total power
dissipation.
\\ ( http://arXiv.org/abs/quant-ph/0605114 , 277kb)
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Paper: quant-ph/0605122
Date: Mon, 15 May 2006 06:00:09 GMT (114kb)

Title: Efficient retrieval of a single excitation stored in an atomic ensemble
Authors: Julien Laurat, Hugues de Riedmatten, Daniel Felinto, Chin-wen Chou,
Erik Schomburg, H. Jeff Kimble
\\
We report significant improvements in the retrieval efficiency of a single
excitation stored in an atomic ensemble and in the subsequent generation of
strongly correlated pairs of photons. A 50% probability to transform the stored
excitation into one photon in a well-defined spatio-temporal mode at the output
of the ensemble is demonstrated. These improvements are illustrated by the
generation of high-quality heralded single photons with a suppression of the
two-photon component below 1% of the value for a coherent state. A broad
characterization of our system is performed for different parameters in order
to provide input for the future design of realistic quantum networks.
\\ ( http://arXiv.org/abs/quant-ph/0605122 , 114kb)
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Paper: quant-ph/0605123
Date: Mon, 15 May 2006 07:18:19 GMT (8kb)

Title: Exact Solutions of a Non-Polynomially Nonlinear Schrodinger Equation
Authors: R. Parwani and H. S. Tan
\\
A nonlinear generalisation of Schrodinger's equation had previously been
obtained using information-theoretic arguments. The nonlinearities in that
equation were of a nonpolynomial form, equivalent to the occurence of
higher-derivative nonlinear terms at all orders. Here we construct some exact
solutions to that equation in 1+1 dimensions. On the half-line, the solutions
resemble exponentially damped Bloch waves even though no external periodic
potential is included: the periodicity is induced by the nonpolynomiality. The
solutions are nonperturbative as they do not reduce to solutions of the linear
theory in the limit that the nonlinearity parameter vanishes. An intriguing
feature of the solutions is their infinite degeneracy: for a given energy,
there exists a very large arbitrariness in the normalisable wavefunctions. We
also consider solutions to a q-deformed version of the nonlinear equation and
discuss a natural discretisation implied by the nonpolynomiality. Finally, we
contrast the properties of our solutions with other solutions of nonlinear
Schrodinger equations in the literature and suggest some possible applications
of our results in the domains of low-energy and high-energy physics.
\\ ( http://arXiv.org/abs/quant-ph/0605123 , 8kb)
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Paper: quant-ph/0605125
Date: Mon, 15 May 2006 13:45:45 GMT (266kb)

Title: Splitting times of doubly quantized vortices in dilute Bose-Einstein
condensates
Authors: J. A. M. Huhtam\"aki (1), M. M\"ott\"onen (2), T. Isoshima (3), V.
Pietil\"a (1), and S. M. M. Virtanen (1) ((1) Laboratory of Physics, Helsinki
University of Technology, Finland, (2) Low Temperature Laboratory, Helsinki
University of Technology, Finland, (3) Institute of Physics, Academia Sinica,
Taiwan)
\\
Recently, the splitting of a topologically created doubly quantized vortex
into two singly quantized vortices was experimentally investigated in dilute
atomic cigar-shaped Bose-Einstein condensates [Y. Shin et al., Phys. Rev. Lett.
93, 160406 (2004)]. In particular, the dependency of the splitting time on the
peak particle density was studied. We present results of theoretical
simulations which closely mimic the experimental set-up. Contrary to previous
theoretical studies, claiming that thermal excitations are the essential
mechanism in initiating the splitting, we show that the combination of
gravitational sag and time dependency of the trapping potential alone suffices
to split the doubly quantized vortex in time scales which are in good agreement
with the experiments. We also study the dynamics of the resulting singly
quantized vortices which typically intertwine--especially, a peculiar vortex
chain structure appears for certain parameter values.
\\ ( http://arXiv.org/abs/quant-ph/0605125 , 266kb)
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Paper: quant-ph/0605129
Date: Mon, 15 May 2006 15:27:16 GMT (388kb)

Title: Phase Space Quantum Mechanics - Direct
Authors: S. Nasiri, Y. Sobouti, and F. Taati
\\
Conventional approach to quantum mechanics in phase space, (q,p), is to take
the operator based quantum mechanics of Schrodinger, or and equivalent, and
assign a c-number function in phase space to it. We propose to begin with a
higher level of abstraction, in which the independence and the symmetric role
of q and p is maintained throughout, and at once arrive at phase space state
functions. Upon reduction to the q- or p-space the proposed formalism gives the
conventional quantum mechanics, however, with a definite rule for ordering of
factors of non commuting observables. Further conceptual and practical merits
of the formalism are demonstrated throughout the text.
\\ ( http://arXiv.org/abs/quant-ph/0605129 , 388kb)
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Paper: physics/0605111
Date: Fri, 12 May 2006 21:50:34 GMT (220kb)

Title: Antiblockade in Rydberg excitation of an ultracold lattice gas
Authors: Cenap Ates, Thomas Pohl, Thomas Pattard, Jan M. Rost
Subj-class: Atomic Physics
\\
It is shown that the two-step excitation scheme typically used to create an
ultracold Rydberg gas can be described with an effective two-level rate
equation, greatly reducing the complexity of the optical Bloch equations. This
allows us to solve the many-body problem of interacting cold atoms with a Monte
Carlo technique. Our results reproduce the Rydberg blockade effect. However, we
demonstrate that an Autler-Townes double peak structure in the two-step
excitation scheme, which occurs for moderate pulse lengths as used in the
experiment, can give rise to an antiblockade effect. It is observable in a
lattice gas with regularly spaced atoms. Since the antiblockade effect is
robust against a large number of lattice defects it should be experimentally
realizable with an optical lattice created by CO$_{2}$ lasers.
\\ ( http://arXiv.org/abs/physics/0605111 , 220kb)
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Paper: cond-mat/0605393
Date: Tue, 16 May 2006 02:50:19 GMT (113kb)

Title: Bose-Einstein condensates in RF-dressed adiabatic potentials
Authors: M. White, H. Gao, M. Pasienski, B. DeMarco
Subj-class: Other
\\
Bose-Einstein condensates of $^{87}$Rb atoms are transferred into
corresponding dressed states are explored. We demonstrate that measurements of
the Zeeman populations of dressed condensates are a sensitive probe of RF
magnetic field strength. We also show that adiabatic potentials can be used to
trap atom gases in novel geometries, including suspending a cigar-shaped cloud
above a curved sheet of atoms.
\\ ( http://arXiv.org/abs/cond-mat/0605393 , 113kb)
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Paper: cond-mat/0605402
Date: Tue, 16 May 2006 09:21:33 GMT (257kb)

Title: Bosonization of Interacting Fermions in Arbitrary Dimensions
Authors: Peter Kopietz (Frankfurt)
Comments: 287 pages, 33 figues. This review has been published in the lecture
note series by Springer Verlag, but it is currently out of print. It will be
available again via Springer Verlag in the future, see
Permission by Springer Verlag to publish this review in this archive has been
obtained
Subj-class: Strongly Correlated Electrons; Statistical Mechanics
Journal-ref: Peter Kopietz, Bosonization of interacting fermions in arbitrary
dimensions, (Springer, Berlin, 1997)
\\
This review is a summary of my work (partially in collaboration with Kurt
Schoenhammer) on higher-dimensional bosonization during the years 1994-1996. It
has been published as a book entitled  Bosonization of interacting fermions
in arbitrary dimensions" by Springer Verlag (Lecture Notes in Physics m48,
Springer, Berlin, 1997). I have NOTrevised this review, so that there is no
reference to the literature after 1996. However, the basic ideas underlying the
functional bosonization approach outlined in this review are still valid today.
\\ ( http://arXiv.org/abs/cond-mat/0605402 , 257kb)
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Paper: cond-mat/0605405
Date: Tue, 16 May 2006 10:10:12 GMT (201kb)

Title: Issues on the transport of one dimensional systems
Authors: X. Zotos
Comments: Conference on "Statistical Physics of Quantum Systems - novel orders
and dynamics -" Sendai, July 2004
Subj-class: Strongly Correlated Electrons; Statistical Mechanics
Journal-ref: Journal of Physical Society of Japan, Suppl. v.74, p.173 (2005)
\\
In this paper, we will critically discuss recent theoretical and experimental
developments on the transport of one dimensional quantum systems. In
particular, we will focus on open issues and controversial results related to
the finite temperature dynamics of integrable quantum models. These singular
systems are commonly used in the description of quasi-one dimensional
materials. They have recently attracted a lot of interest in connection to the
interpretation of experiments, specially after the discovery of unusual thermal
conductivity in magnetic compounds.
\\ ( http://arXiv.org/abs/cond-mat/0605405 , 201kb)
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Paper: cond-mat/0605407
Date: Tue, 16 May 2006 10:18:11 GMT (91kb)

Title: Dimensional Effects on Solitonic Matter and Optical Waves with Normal
and Anomalous Dispersion
Authors: L. Salasnich, A. Parola and L. Reatto
Comments: To be published in Journal of Physics B: At. Mol. Opt. Phys
Subj-class: Other; Statistical Mechanics
\\
We investigate bright and dark solitons with anomalous or normal dispersion
and under transverse harmonic confinement. In matter waves, positive atomic
mass implies anomalous dispersion (kinetic spreading) while negative mass gives
normal dispersion (kinetic shrinking). We find that, contrary to the strictly
one-dimensional case, the axial and transverse profiles of these solitons
crucially depend on the strength of the nonlinearity and on their dispersive
properties. In particular, we show that, like bright solitons with anomalous
dispersion, also dark solitons with normal dispersion disappear at a critical
axial density. Our predictions are useful for the study of atomic matter waves
in Bose-Einstein condensates and also for optical bullets in inhomogeneous Kerr
media.
\\ ( http://arXiv.org/abs/cond-mat/0605407 , 91kb)
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Paper: cond-mat/0605409
Date: Tue, 16 May 2006 11:53:41 GMT (69kb)

Title: Bogoliubov modes of a dipolar condensate in a cylindrical trap
Authors: Shai Ronen, Daniele E. C. Bortolotti, and John L. Bohn
Subj-class: Statistical Mechanics
\\
The calculation of properties of Bose-Einstein condensates with dipolar
interactions has proven a computationally intensive problem due to the long
range nature of the interactions, limiting the scope of applications. In
particular, the lowest lying Bogoliubov excitations in three dimensional
harmonic trap with cylindrical symmetry were so far computed in an indirect
way, by Fourier analysis of time dependent perturbations, or by approximate
variational methods. We have developed a very fast and accurate numerical
algorithm based on the Hankel transform for calculating properties of dipolar
Bose-Einstein condensates in cylindrically symmetric traps. As an application,
we are able to compute many excitation modes by directly solving the
Bogoliubov-De Gennes equations. We explore the behavior of the excited modes in
different trap geometries. We use these results to calculate the quantum
depletion of the condensate by a combination of a computation of the exact
modes and the use of a local density approximation.
\\ ( http://arXiv.org/abs/cond-mat/0605409 , 69kb)
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Paper: cond-mat/0605410
Date: Tue, 16 May 2006 12:27:02 GMT (22kb)

Title: The Hall effect of dipole chain in one dimensional Bose-Einstein
condensation
Authors: Tieyan Si, Yue Yu
Subj-class: Mesoscopic Systems and Quantum Hall Effect; Statistical Mechanics
\\
We find a breather behavior of the dipole chain, this breather excitation
obey fractional statistics, it could be an experimental quantity to detect
anyon. A Hall effect of magnetic monopole in a dipole chain of ultracold
molecules is also presented, we show that this Hall effect can induce the flip
of magnetic dipole chain.
\\ ( http://arXiv.org/abs/cond-mat/0605410 , 22kb)
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Paper: cond-mat/0605412
Date: Tue, 16 May 2006 13:33:05 GMT (146kb)

Title: Solitons in coupled atomic-molecular Bose-Einstein condensates in a trap
Authors: B. Oles and K. Sacha
Subj-class: Other; Statistical Mechanics
\\
We consider coupled atomic-molecular Bose-Einstein condensate system in a
quasi-one-dimensional trap. In the vicinity of a Feshbach resonance the system
can reveal soliton-like behavior. We analyze bright soliton solutions for the
system in the trap and in the presence of the interactions between particles.
We show that with increasing number of particles in the system two bright
soliton solutions start resembling dark soliton profiles known in an atomic
Bose-Einstein condensate with repulsive interactions between atoms. We analyze
also methods for experimental preparation and detection of the soliton states.
\\ ( http://arXiv.org/abs/cond-mat/0605412 , 146kb)
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Paper: cond-mat/0605413
Date: Tue, 16 May 2006 13:54:45 GMT (26kb)

Title: Collective mode damping and viscosity in a 1D unitary Fermi gas
Authors: M. Punk, W. Zwerger
Comments: 9 pages, 3 figures, submitted to New J. Phys
Subj-class: Statistical Mechanics; Superconductivity
\\
We calculate the damping of the Bogoliubov-Anderson mode in a one-dimensional
two-component attractive Fermi gas for arbitrary coupling strength within a
quantum hydrodynamic approach. Using the Bethe-Ansatz solution of the 1D
BCS-BEC crossover problem, we derive analytic results for the viscosity
covering the full range from a Luther-Emery liquid of weakly bound pairs to a
Lieb-Liniger gas of strongly bound bosonic dimers. At the unitarity point, the
system is a Tonks-Girardeau gas with a universal constant $\alpha_{\zeta}=0.38$
in the viscosity $\zeta=\alpha_{\zeta}\hbar n$ for T=0. For the trapped case,
we calculate the Q-factor of the breathing mode and show that the damping
provides a sensitive measure of temperature in 1D Fermi gases.
\\ ( http://arXiv.org/abs/cond-mat/0605413 , 26kb)
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Paper: cond-mat/0605419
Date: Tue, 16 May 2006 17:57:01 GMT (114kb)

Title: Interacting Bose gases in quasi-one dimensional optical lattices
Authors: M. A. Cazalilla, A. F. Ho, and T. Giamarchi
Comments: 55 pages + 5 EPS figures; submitted to NJP
Subj-class: Mesoscopic Systems and Quantum Hall Effect; Statistical Mechanics
\\
We study a two-dimensional array of coupled one-dimensional (1D) tubes of
interacting bosons. Such systems can be produced by loading ultra-cold atoms in
anisotropic optical lattices. We investigate the effects of coupling the tubes
via hopping of the bosons (i.e. Josephson coupling). In the absence of a
periodic potential along the tubes, or when such potential is incommensurate
with the boson density, the system undergoes a transition from an array of
incoherent Tomonaga-Luttinger liquids at high temperature to an anisotropic
Bose-Einstein condensate (BEC), at low temperature. We determine the transition
temperature and long wave-length excitations of the BEC. In addition to the
usual gapless (Goldstone) mode found in standard superfluids, we also find a
gapped mode associated with fluctuations of the amplitude of the order
parameter. When a commensurate periodic potential is applied along the tubes,
they can become 1D Mott insulators. Intertube hopping leads to a deconfinement
quantum phase transition between the 1D Mott insulators and the anisotropic
BEC. We also take into account the finite size of the gas tubes as realized in
actual experiments. We map out the phase diagram of the quasi-1D lattice and
compare our results with the existing experiments on such systems.
\\ ( http://arXiv.org/abs/cond-mat/0605419 , 114kb)
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Paper: cond-mat/0605005
replaced with revised version Tue, 16 May 2006 01:37:43 GMT (50kb)

Title: Phase Transition in Imbalanced Fermion Superfluids
Authors: Heron Caldas
Comments: This is an invited contribution to a book titled "Pairing beyond BCS
Theory in Fermionic Systems" (Mark Alford, John Clark and Armen Sedrakian,
references
Subj-class: Superconductivity; Strongly Correlated Electrons
\\ ( http://arXiv.org/abs/cond-mat/0605005 , 50kb)
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Paper: quant-ph/0605139
Date: Tue, 16 May 2006 14:38:26 GMT (98kb)

Title: Decay by tunneling of Bosonic and Fermionic Tonks-Girardeau Gases
Authors: A. del Campo, F. Delgado, G. Garcia-Calderon, J. G. Muga, and M. G.
Raizen
\\
We study the tunneling dynamics of bosonic and fermionic Tonks-Girardeau
gases from a hard wall trap, in which one of the walls is substituted by a
delta potential. Using the Fermi-Bose map, the decay of the probability to
remain in the trap is studied as a function of both the number of particles and
the intensity of the end-cap delta laser. The fermionic gas is shown to be a
good candidate to study deviations of the non-exponential decay of the
single-particle type, whereas for the bosonic case a novel regime of
non-exponential decay appears due to the contributions of different resonances
of the trap.
\\ ( http://arXiv.org/abs/quant-ph/0605139 , 98kb)
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\\
Paper: physics/0605134
Date: Tue, 16 May 2006 11:22:50 GMT (100kb)

Title: Exploring the van der Waals Atom-Surface attraction in the nanometric
range
Authors: Mich\{e}le Fichet (LPL), Gabriel Dutier (LPL), Alexander Yarovitski
(LPL), Petko Todorov (LPL), Ismah\{e}ne Hamdi (LPL), Isabelle Maurin (LPL),
Solomon Saltiel (LPL), David Sarkisyan (IPR), Marie-Pascale Gorza (LPL),
Daniel Bloch (LPL), Martial Ducloy (LPL)
Proxy: ccsd ccsd-00069106
Subj-class: Atomic Physics
\\
The van der Waals atom-surface attraction, scaling as C3 z-3 for z the
atom-surface distance, is expected to be valid for ~ 1-1000 nm, covering 8-10
orders of magnitudes in the interaction energy. Thanks to a Cs vapor nanocell,
we analyze the spectroscopic modifications induced by the atom-surface
attraction on the 6P3/2->6D5/2 transition. The C3 value, extracted
independently for various thicknesses ranging from 40 nm to 130 nm, is found to
be independent of the thickness. It agrees, but only within a factor of 2, with
an elementary theoretical prediction, whose validity is discussed.
\\ ( http://arXiv.org/abs/physics/0605134 , 100kb)
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\\
Paper (*cross-listing*): nlin.PS/0605032
Date: Tue, 16 May 2006 09:27:06 GMT (551kb)

Title: Stable circulation modes in a dual-core matter-wave soliton laser
Authors: Peter Y. P. Chen (School of Mechanical and Manufacturing Engineering,
University of New South Wales, Sydney, Australia) and Boris A. Malomed
(Department of Interdisciplinary Studies, School of Electrical Engineering,
Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel)
Comments: J. of Physics B: At. Mol. Opt. Physics, in press
Subj-class: Pattern Formation and Solitons; Soft Condensed Matter
\\
We consider a model of a matter-wave laser generating a periodic array of
solitary-wave pulses. The system, a general version of which was recently
proposed in Ref. [5], is composed of two parallel tunnel-coupled cigar-shaped
traps (a reservoir and a lasing cavity), solitons being released through a
valve at one edge of the cavity. We report a stable lasing mode accounted for
by circulations of a narrow soliton in the cavity, which generates an array of
strong pulses (with 1,000 - 10,000 atoms in each, the array's duty cycle ~ 30%)
when the soliton periodically hits the valve.
\\ ( http://arXiv.org/abs/nlin/0605032 , 551kb)
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\\
Paper (*cross-listing*): nlin.PS/0605035
Date: Tue, 16 May 2006 18:38:53 GMT (336kb)

Title: Stationary localized modes in the quintic nonlinear Schrodinger equation
with a periodic potential
Authors: G. L. Alfimov, V. V. Konotop, P. Pacciani
Subj-class: Pattern Formation and Solitons; Other
\\
We consider one-dimensional quintic nonlinear Schr\"{o}dinger equation with a
periodic potential. In the case of attractive nonlinearity we deduce sufficient
condition for collapse. We show that there exist spatially localized solutions
with arbitrarily large number of particles. We study such solutions in the
semi-infinite gap (attractive case) and in the first gap (attractive and
repulsive cases) and show that a nonzero minimum value of the number of
particles is necessary for a mode to be created. In the limit of large negative
frequencies (attractive case) we observe quantization'' of the number of
particles of the stationary modes. Such solutions can be interpreted as coupled
Townes'' solitons and appear to be stable. The modes in the first gap have
numbers of particles infinitely growing with frequencies approaching one of the
gap edges, what is explained by the power decay of the modes. Gap solitons are
found to be unstable.
\\ ( http://arXiv.org/abs/nlin/0605035 , 336kb)
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\\
Paper: cond-mat/0601147
replaced with revised version Wed, 17 May 2006 08:51:37 GMT (889kb)

Title: LOFF Pairing vs. Breached Pairing in Asymmetric Fermion Superfluids
Authors: Lianyi He, Meng Jin and Pengfei Zhuang
Comments: 12 pages, 13 figures, version to appear in Physical Review B
Subj-class: Superconductivity
\\ ( http://arXiv.org/abs/cond-mat/0601147 , 889kb)
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\\
Paper: cond-mat/0601302
replaced with revised version Tue, 16 May 2006 21:24:54 GMT (20kb)

Title: Quantum magnetism with multicomponent polar molecules in an optical
lattice
Authors: Ryan Barnett, Dmitry Petrov, Mikhail Lukin, Eugene Demler
Subj-class: Strongly Correlated Electrons
Journal-ref: Phys. Rev. Lett. 96, 190401 (2006)
\\ ( http://arXiv.org/abs/cond-mat/0601302 , 20kb)
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\\
Paper: cond-mat/0603458
replaced with revised version Wed, 17 May 2006 16:17:07 GMT (100kb)

Title: Dynamic response of one-dimensional interacting fermions
Authors: M. Pustilnik, M. Khodas, A. Kamenev, L.I. Glazman
Subj-class: Mesoscopic Systems and Quantum Hall Effect; Strongly Correlated
Electrons
Journal-ref: Phys. Rev. Lett. 96, 196405 (2006)
DOI: 10.1103/PhysRevLett.96.196405
\\ ( http://arXiv.org/abs/cond-mat/0603458 , 100kb)
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\\
Paper: cond-mat/0605138
replaced with revised version Wed, 17 May 2006 13:49:25 GMT (52kb)

Title: Landau functions for non-interacting bosons
Authors: Andreas Sinner, Florian Schuetz, and Peter Kopietz
Subj-class: Statistical Mechanics
\\ ( http://arXiv.org/abs/cond-mat/0605138 , 52kb)
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\\
Paper (*cross-listing*): hep-th/0510238
replaced with revised version Wed, 17 May 2006 11:40:35 GMT (10kb)

Title: Casimir forces in Bose-Einstein condensates: finite size effects in
three-dimensional rectangular cavities
Authors: Ariel Edery
Comments: 12 pages; no figures; v.2: version accepted for publication in JSTAT
Subj-class: High Energy Physics - Theory; Statistical Mechanics
\\ ( http://arXiv.org/abs/hep-th/0510238 , 10kb)
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\\
Paper: physics/0605152
Date: Wed, 17 May 2006 16:59:14 GMT (11kb)

Title: Five Frequently Fatal Freshman Physics Fantasies
Authors: Michael Courtney, Norm Althausen, and Amy Courtney
Comments: 3 pages, submitted to The Physics Teacher
Subj-class: Physics Education
\\
college-level Physics courses: the miracle finish, the soft hearted professor,
an extension of high school, weak areas won't be tested, and passing is more
important than learning. These fantasies are unique to neither Physics nor
freshman, but the challenge of learning Physics brings more certain negative
consequences to students retaining these attitudes. Ascribing these student
misconceptions to freshmen acknowledges that they diminish with increasing
\\ ( http://arXiv.org/abs/physics/0605152 , 11kb)
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\\
Paper: cond-mat/0605440
Date: Thu, 18 May 2006 15:54:43 GMT (373kb)

Title: Detecting the breached pair phase in a polarized ultracold Fermi gas
Authors: W. Yi and L.-M. Duan
Subj-class: Other
\\
We propose a method for the experimental detection of a new quantum phase,
the breached pair state, in a strongly interacting ultracold Fermi gas with
population imbalance. We show that through the time-of-flight Raman imaging,
the presence of such a phase can be unambiguously determined with a measurement
of the momentum-space phase separation of the minority spin component. To guide
the experimental efforts, the momentum-space density profiles are calculated
under typical experimental conditions.
\\ ( http://arXiv.org/abs/cond-mat/0605440 , 373kb)
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\\
Paper: cond-mat/0605459
Date: Thu, 18 May 2006 11:58:13 GMT (45kb)

Title: Critical Velocities for Energy Dissipation from Periodic Motions of
Impurity in Bose-Einstein Condensates
Authors: Jun Suzuki
Subj-class: Statistical Mechanics; Other
\\
A phenomenon of energy dissipation in Bose-Einstein condensates is studied
based on a microscopic model for the motion of impurity. Critical velocities
for onset of energy dissipation are obtained for periodic motions, such as a
dipole-like oscillation and a circular motion. The first example is similar to
a series of MIT group experiments settings where the critical velocity was
observed much below the Landau critical velocity. The appearance of the smaller
values for the critical velocity is also found in our model, even in the
homogeneous condensate in the thermodynamic limit. This suggests that the
landau criterion be reexamined in the absence of quantized vortices in the bulk
limit.
\\ ( http://arXiv.org/abs/cond-mat/0605459 , 45kb)
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\\
Paper: cond-mat/0605163
replaced with revised version Thu, 18 May 2006 14:33:31 GMT (156kb)

Title: Mean-field phase diagram of disordered bosons in a lattice at non-zero
temperature
Authors: K.V.Krutitsky, A.Pelster and R.Graham
Subj-class: Other; Disordered Systems and Neural Networks
\\ ( http://arXiv.org/abs/cond-mat/0605163 , 156kb)
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\\
Paper: cond-mat/0605419
replaced with revised version Thu, 18 May 2006 17:30:17 GMT (114kb)

Title: Interacting Bose gases in quasi-one dimensional optical lattices
Authors: M. A. Cazalilla, A. F. Ho, and T. Giamarchi
Comments: 55 pages + 5 EPS figures; submitted to NJP; v2: reference added
Subj-class: Mesoscopic Systems and Quantum Hall Effect; Statistical Mechanics
\\ ( http://arXiv.org/abs/cond-mat/0605419 , 114kb)
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\\
Paper: quant-ph/0605163
Date: Thu, 18 May 2006 19:23:40 GMT (617kb)

Title: Quantum Information Processing in Optical Lattices and Magnetic
Microtraps
Authors: Philipp Treutlein, Tilo Steinmetz, Yves Colombe, Peter Hommelhoff,
Jakob Reichel, Markus Greiner, Olaf Mandel, Arthur Widera, Tim Rom, Immanuel
Bloch, and Theodor W. H\"ansch
\\
We review our experiments on quantum information processing with neutral
atoms in optical lattices and magnetic microtraps.
Atoms in an optical lattice in the Mott insulator regime serve as a large
qubit register. A spin-dependent lattice is used to split and delocalize the
atomic wave functions in a controlled and coherent way over a defined number of
lattice sites. This is used to experimentally demonstrate a massively parallel
quantum gate array, which allows the creation of a highly entangled many-body
cluster state through coherent collisions between atoms on neighbouring lattice
sites.
In magnetic microtraps on an atom chip, we demonstrate coherent manipulation
of atomic qubit states and measure coherence lifetimes exceeding one second at
micron-distance from the chip surface. We show that microwave near-fields on
the chip can be used to create state-dependent potentials for the
implementation of a quantum controlled phase gate with these robust qubit
states. For single atom detection and preparation, we have developed high
finesse fiber Fabry-Perot cavities and integrated them on the atom chip. We
present an experiment in which we detected a very small number of cold atoms
magnetically trapped in the cavity using the atom chip.
\\ ( http://arXiv.org/abs/quant-ph/0605163 , 617kb)
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\\
Paper: physics/0605159
Date: Thu, 18 May 2006 09:35:10 GMT (568kb)

Title: Collisional shifts in optical-lattice atom clocks
Authors: Y. B. Band and A. Vardi
Subj-class: Atomic Physics; General Physics
\\
We theoretically study the effects of elastic collisions on the determination
of frequency standards via Ramsey fringe spectroscopy in optical-lattice atom
clocks. Interparticle interactions of bosonic atoms in multiply-occupied
lattice sites can cause a linear frequency shift, as well as generate
asymmetric Ramsey fringe patterns and reduce fringe visibility due to
interparticle entanglement. We propose a method of reducing these collisional
effects in an optical lattice by introducing a phase difference of $\pi$
between the Ramsey driving fields in adjacent sites. This configuration
suppresses site to site hopping due to interference of two tunneling pathways,
without degrading fringe visibility. Consequently, the probability of double
occupancy is reduced, leading to cancellation of collisional shifts.
\\ ( http://arXiv.org/abs/physics/0605159 , 568kb)
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\\
Paper: cond-mat/0605486
Date: Fri, 19 May 2006 13:47:16 GMT (205kb)

Title: The two-site Bose--Hubbard model
Authors: J. Links, A. Foerster, A. Tonel and G. Santos
Comments: 10 pages, 5 figures, submitted for publication in Annales Henri
Poincare
Subj-class: Other
\\
The two-site Bose--Hubbard model is a simple model used to study Josephson
tunneling between two Bose--Einstein condensates. In this work we give an
overview of some mathematical aspects of this model. Using a classical
analysis, we study the equations of motion and the level curves of the
Hamiltonian. Then, the quantum dynamics of the model is investigated using
direct diagonalisation of the Hamiltonian. In both of these analyses, the
existence of a threshold coupling between a delocalised and a self-trapped
phase is evident, in qualitative agreement with experiments. We end with a
discussion of the exact solvability of the model via the algebraic Bethe
ansatz.
\\ ( http://arXiv.org/abs/cond-mat/0605486 , 205kb)
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\\
Paper: cond-mat/0605494
Date: Fri, 19 May 2006 17:04:03 GMT (15kb)

Title: Response functions and superfluid density in a weakly interacting Bose
Authors: Jonathan Keeling
Subj-class: Mesoscopic Systems and Quantum Hall Effect
\\
Motivated by the experimental search for Bose condensation of quasiparticles
in semiconductors, the response functions of a weakly interacting Bose gas,
dispersion modifies the definition of particle current, and leads to modified
sum rules for the current-current response function. The effect of these
modifications on the Berezhinski-Kosterlitz-Thouless transition is discussed.
\\ ( http://arXiv.org/abs/cond-mat/0605494 , 15kb)
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\\
Paper: cond-mat/0601314
replaced with revised version Fri, 19 May 2006 18:32:31 GMT (447kb)

Title: Profiles of near-resonant population-imbalanced trapped Fermi gases
Authors: Theja N. De Silva, Erich J. Mueller
Comments: 4 pages, 5 Figures, Published version
Subj-class: Other
Journal-ref: Phys. Rev. A 73, 051602(R) (2006)
DOI: 10.1103/PhysRevA.73.051602
\\ ( http://arXiv.org/abs/cond-mat/0601314 , 447kb)
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\\
Paper: quant-ph/0605168
Date: Thu, 18 May 2006 21:34:46 GMT (318kb)

Title: Field autocorrelations in electromagnetically induced transparency:
Effects of a squeezed probe field
Authors: P. Barberis-Blostein
\\
The interaction of a quantized field with three-level atoms in $\Lambda$
configuration inside a two mode cavity is analyzed. We calculate the stationary
quadrature noise spectrum of the field outside the cavity in the case where the
input probe field is in a squeezed state and the atoms show electromagnetically
induced transparency (EIT). If the Rabi frequencies of both dipole transitions
of the atoms are different from zero, we show that the output probe field have
four maxima of squeezing absorption. We show that in some cases two of these
frequencies can be very close to the transition frequency of the atom, in a
region where the mean value of the field entering the cavity is hardly altered.
Furthermore, part of the absorbed squeezing of the probe field is transfered to
the pump field. For some conditions this transfer of squeezing can be complete.
\\ ( http://arXiv.org/abs/quant-ph/0605168 , 318kb)
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\\
Paper: quant-ph/0602048
replaced with revised version Fri, 19 May 2006 16:34:39 GMT (10kb)

Title: Single-Site Entanglement of Fermions at a Quantum Phase Transition
Authors: Daniel Larsson and Henrik Johannesson
Comments: 4 pages, no figure. Published version
Subj-class: Quantum Physics; Strongly Correlated Electrons
Journal-ref: Phys. Rev. A 73, 042320 (2006)
\\ ( http://arXiv.org/abs/quant-ph/0602048 , 10kb)
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Till next week,
Matt.

--
-------------------------------------------------------------------------
Dr M. J. Davis,               Senior Lecturer in Physics
School of Physical Sciences,  email: mdavis_at_physics.uq.edu.au
University of Queensland,     ph   : +61 7 334 69824
Brisbane, QLD 4072,           fax  : +61 7 336 51242
Australia.                    http://www.physics.uq.edu.au/people/mdavis/
-------------------------------------------------------------------------

Received on Mon May 22 2006 - 18:04:39 EST

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