Matt's arXiv selection, Monday 13th March 2006.

From: Matthew Davis <>
Date: Mon, 13 Mar 2006 09:17:47 +1000 (EST)

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Have a good week,

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
Paper: cond-mat/0603056
Date: Thu, 2 Mar 2006 22:00:44 GMT   (22kb)
Title: Bose atoms in a trap: a variational Monte Carlo formulation for the
   universal behavior at the Van der Waals length scale
Authors: Imran Khan and Bo Gao
Comments: 6 pages, 4 figures
Subj-class: Statistical Mechanics
   We present a variational Monte Carlo (VMC) formulation for the universal
equations of state at the Van der Waals length scale [B. Gao, J. Phys. B
\textbf{37}, L227 (2004)] for $N$ Bose atoms in a trap. The theory illustrates
both how such equations of state can be computed exactly, and the existence and
the importance of long-range atom-atom correlation under strong confinement.
Explicit numerical results are presented for N=3 and 5, and used to provide a
quantitative understanding of the shape-dependent confinement correction that
is important for few atoms under strong confinement.
\\ ( ,  22kb)
Paper: cond-mat/0603059
Date: Fri, 3 Mar 2006 00:44:12 GMT   (151kb)
Title: Collisions between solitary waves of three-dimensional Bose-Einstein
Authors: N.G. Parker, A. M. Martin, S. L. Cornish and C. S. Adams
Comments: 5 pages, 4 figures
Subj-class: Other
   We study bright solitary waves of three dimensional trapped Bose-Einstein
condensates and their collisions. For a single solitary wave, in addition to an
upper critical number, we also find a {\em lower} cut-off, below which no
stable state can be found. Collisions between solitary waves can be elastic,
inelastic with either reduced or increased outgoing speed, or completely
unstable due to a collapse instability. A $\pi$-phase difference between the
waves promotes elastic collisions, and gives excellent agreement with recent
experimental results over long timescales.
\\ ( ,  151kb)
Paper: cond-mat/0603070
Date: Fri, 3 Mar 2006 10:51:43 GMT   (260kb)
Title: Dark solitons in F=1 spinor Bose--Einstein condensate
Authors: Masaru Uchiyama, Jun'ichi Ieda, Miki Wadati
Comments: 19 pages, 3 figures
Subj-class: Other; Soft Condensed Matter
   We study dark soliton solutions of a multi-component Gross--Pitaevskii
equation for hyperfine spin F=1 spinor Bose--Einstein condensate. The
interactions are supposed to be inter-atomic repulsive and anti-ferromagnetic
ones of equal magnitude. The solutions are obtained from those of an integrable
$2\times 2$ matrix nonlinear Schr\"{o}dinger equation with nonvanishing
boundary conditions. We investigate the one-soliton and two-soliton solutions
in detail. One-soliton is classified into two kinds. The ferromagnetic state
has wavefunctions of domain-wall shape and its total spin is nonzero. The polar
state provides a hole soliton and its total spin is zero. These two states are
selected by choosing the type of the boundary conditions. In two-soliton
collisions, we observe the spin-mixing or spin-transfer. It is found that, as
"magnetic" carriers, solitons in the ferromagnetic state are operative for the
spin-mixing while those in the polar are passive.
\\ ( ,  260kb)
Paper: cond-mat/0603071
Date: Fri, 3 Mar 2006 10:03:49 GMT   (5kb)
Title: Generalized Thermostatistics and Bose-Einstein Condensation
Authors: H. G. Miller, F. C. Khanna, R.Teshima, A.R. Plastino and A. Plastino
Subj-class: Statistical Mechanics
   Analytical expressions for Bose-Einstein condensation of an ideal Bose gas
analyzed within the strictures of non-extensive, generalized thermostatistics
are here obtained.
\\ ( ,  5kb)
Paper: cond-mat/0603082
Date: Fri, 3 Mar 2006 16:15:48 GMT   (2921kb)
Title: Liquid 4He: contributions to first principles theory of quantized
   vortices, thermohydrodynamic properties, and the lambda transition
Authors: H.W. Jackson
Comments: 155 pages, 28 figures
Subj-class: Statistical Mechanics
   Liquid 4He has been studied extensively for almost a century, but there are
still a number of outstanding weak or missing links in our comprehension of it.
This paper reviews some of the principal paths taken in previous research and
then proceeds to fill gaps and create an integrated picture with more complete
understanding through first principles treatment of a realistic model that
starts with a microscopic, atomistic description of the liquid. Newly derived
results for vortex cores and thermohydrodynamic properties for a two-fluid
model are used to show that interacting quantized vortices may produce a lambda
anomaly in specific heat near the superfluid transition where flow properties
change. The nature of the order in the superfluid state is explained.
Experimental support for new calculations is exhibited, and a unique specific
heat experiment is proposed to test predictions of the theory. Relevance of the
theory to modern research in cosmology, astrophysics, and Bose-Einstein
condensates is discussed.
\\ ( ,  2921kb)
Paper: cond-mat/0603083
Date: Fri, 3 Mar 2006 16:39:15 GMT   (38kb)
Title: Spin Hall Effect in Atoms
Authors: Xiong-Jun Liu, Xin Liu, L. C. Kwek, and C. H. Oh
Comments: 4 pages, 1 figure
Subj-class: Mesoscopic Systems and Quantum Hall Effect
   We investigate a new type of spin hall effect (SHE) in neutral atomic system
by coupling atoms' internal freedom (atom spin states) to radiation. Atoms with
opposite spin polarization are shown to experience opposite effective
electromagnetic fields, and then can move in the opposite direction. For this
pure spin currents in atomic system are obtained, i.e. no massive current
occurs in this way. Besides, we show for special case the spin currents created
in present way can exhibit interesting topological properties.
\\ ( ,  38kb)
Paper: cond-mat/0511206
replaced with revised version Thu, 2 Mar 2006 21:18:59 GMT   (21kb)
Title: Solitons of Bose-Fermi mixtures in a strongly elongated trap
Authors: J. Santhanam, V. M. Kenkre, V. V. Konotop
Comments: 1 figure
Subj-class: Other
Journal-ref: Physical Review A, Volume 73, Number 1, 013612 (2006)
\\ ( ,  21kb)
Paper: quant-ph/0603025
Date: Fri, 3 Mar 2006 13:43:32 GMT   (661kb)
Title: Intensity correlation and anticorrelations in coherently prepared atomic
Authors: Gombojav O. Ariunbold, Vladimir A. Sautenkov, Yuri V. Rostovtsev, and
   Marlan O. Scully
   Motivated by the recent experiment [V.A. Sautenkov, Yu.V. Rostovtsev, and
M.O. Scully, Phys. Rev. A 72, 065801 (2005)], we develop a theoretical model in
which the field intensity fluctuations resulted from resonant interaction of a
dense atomic medium with laser field having finite bandwidth. The
intensity-intensity cross correlation between two circular polarized beams can
be controlled by the applied external magnetic field. A smooth transition from
perfect correlations to anti-correlations (at zero delay time) of the outgoing
beams as a function of the magnetic field strength is observed. It provides us
with the desired information about decoherence rate in, for example, $^{87}$Rb
atomic vapor.
\\ ( ,  661kb)
Paper: quant-ph/0603028
Date: Fri, 3 Mar 2006 17:33:37 GMT   (291kb)
Title: Simultaneous Magneto-Optical Trapping of Bosonic and Fermionic Chromium
Authors: R. Chicireanu, A. Pouderous, R. Barbe, B. Laburthe-Tolra, E. Marechal,
   L. Vernac, J.-C. Keller, and O. Gorceix
Comments: 8 pages, 5 figures. submitted to Phys Rev A
   We report on magneto-optical trapping of fermionic 53Cr atoms. A
Zeeman-slowed atomic beam provides loading rates up to 3 10^6 /s. We present
systematic characterization of the magneto-optical trap (MOT). We obtain up to
5 10^5 atoms in the steady state MOT. The atoms radiatively decay from the
excited P state into metastable D states, and, due to the large dipolar
magnetic moment of chromium atoms in these states, they can remain magnetically
trapped in the quadrupole field gradient of the MOT. We study the accumulation
of metastable 53Cr atoms into this magnetic trap. We also report on the first
simultaneous magneto-optical trapping of bosonic 52Cr and fermionic 53Cr atoms.
Finally, we characterize the light assisted collision losses in this Bose-Fermi
cold mixture.
\\ ( ,  291kb)
Paper: physics/0512084
replaced with revised version Thu, 2 Mar 2006 01:36:45 GMT   (81kb)
Title: Direct excitation of the forbidden clock transition in neutral 174Yb
   atoms confined to an optical lattice
Authors: Zeb W. Barber (1), Chad W. Hoyt (1), Chris W. Oates (1), Leo Hollberg
   (1), Aleksei V. Taichenachev (2), Valera I. Yudin (2) ((1) NIST-Boulder, (2)
Comments: Submitted to Physics Review Letters
Subj-class: Atomic Physics
\\ ( ,  81kb)
Paper: cond-mat/0603091
Date: Sat, 4 Mar 2006 17:51:02 GMT   (64kb)
Title: Fermion pairing with population imbalance: energy landscape and phase
   separation in a constrained Hilbert subspace
Authors: Zheng-Cheng Gu, Geoff Warner and Fei Zhou (UBC)
Comments: 4 pages, 3 figures
Subj-class: Other
   In this Letter we map out the mean field energy potential landscape of
fermion pairing states with population imbalance near broad Feshbach
Resonances. We apply the landscape to investigate the nature of phase
separation, when the Hilbert space is subject to the constraint of constant
population imbalance. We calculate the scattering length dependence of the
critical population imbalance for various phase separated states across
Feshbach resonances.
\\ ( ,  64kb)
Paper: cond-mat/0603093
Date: Sat, 4 Mar 2006 05:14:32 GMT   (179kb)
Title: The q-deformed Bose gas: Integrability and thermodynamics
Authors: Michael Bortz and Sergey Sergeev
Comments: 10 pages, 6 figures
Subj-class: Statistical Mechanics
   We investigate the exact solution of the q-deformed one-dimensional Bose gas
to derive all integrals of motion and their corresponding eigenvalues. As an
application, the thermodynamics is given and compared to an effective field
theory at low temperatures.
\\ ( ,  179kb)
Paper: cond-mat/0603094
Date: Sat, 4 Mar 2006 07:06:54 GMT   (104kb)
Title: Electromagnetically induced transparency in an atom-molecule
   Bose-Einstein condensate
Authors: Guang-Ri Jin, Chul Koo Kim, and Kyun Nahm
Comments: 3.7pages, 4 figures
Subj-class: Other
   We propose a new measurement scheme for the atom-molecule dark state by using
electromagnetically induced transparency (EIT) technique. Based on a
density-matrix formalism, we calculate the absorption coefficient numerically.
The appearance of the EIT dip in the spectra profile gives clear evidence for
the creation of the dark state in the atom-molecule Bose-Einstein condensate.
\\ ( ,  104kb)
Paper: cond-mat/0603106
Date: Sun, 5 Mar 2006 18:21:53 GMT   (124kb)
Title: Kinetics of quantum fluctuations in the Bose-Einstein condensation of
Authors: Davide Sarchi, Vincenzo Savona
Subj-class: Materials Science; Mesoscopic Systems and Quantum Hall Effect;
   We develop a kinetic theory of polariton non-equilibrium Bose-Einstein
condensation, in which the field dynamics of collective excitations is treated
self-consistently along with the condensation kinetics. The theory accounts
properly for the dominant role of quantum fluctuations in the condensate. In
realistic situations with optical excitation at high energy, it predicts a
considerable depletion of the condensate caused by long-wavelength
fluctuations. We discuss how this depletion and the subsequent partial
suppression of long-range order depend on the finite size of the system.
\\ ( ,  124kb)
Paper: cond-mat/0603113
Date: Mon, 6 Mar 2006 03:14:21 GMT   (27kb)
Title: Stability analysis for $n$-component Bose-Einstein condensate
Authors: David C. Roberts and Masahito Ueda
Subj-class: Other; Statistical Mechanics
   We derive the dynamic and thermodynamic stability conditions for dilute
multicomponent Bose-Einstein condensates (BECs). These stability conditions,
generalized for $n$-component BECs, are found to be equivalent and are shown to
be consistent with the phase diagrams of two- and three-component condensates
that are derived from energetic arguments.
\\ ( ,  27kb)
Paper: cond-mat/0603118
Date: Mon, 6 Mar 2006 15:06:36 GMT   (258kb)
Title: Interacting Fermi Gases in Disordered One-Dimensional Lattices
Authors: Gao Xianlong, M. Polini, B. Tanatar, and M.P. Tosi
Comments: 7 pages, 4 figures, submitted
Subj-class: Strongly Correlated Electrons; Disordered Systems and Neural
   Interacting two-component Fermi gases loaded in a one-dimensional (1D)
lattice and subject to harmonic trapping exhibit intriguing compound phases in
which fluid regions coexist with local Mott-insulator and/or band-insulator
regions. Motivated by experiments on cold atoms inside disordered optical
lattices, we present a theoretical study of the effects of a random potential
on these ground-state phases. Within a density-functional scheme we show that
disorder has two main effects: (i) it destroys the local insulating regions if
it is sufficiently strong compared with the on-site atom-atom repulsion, and
(ii) it induces an anomaly in the compressibility at low density from quenching
of percolation.
\\ ( ,  258kb)
Paper (*cross-listing*): nlin.SI/0603010
Date: Fri, 3 Mar 2006 10:54:11 GMT   (25kb)
Title: Inverse scattering method for the multicomponent nonlinear Schr\"odinger
   equation under nonvanishing boundary conditions
Authors: Jun'ichi Ieda, Masaru Uchiyama, Miki Wadati
Comments: 22 pages, 2 figures
Subj-class: Exactly Solvable and Integrable Systems; Mathematical Physics;
   Matrix generalization of the inverse scattering method is developed to solve
the multicomponent nonlinear Schr\"odinger equation with nonvanishing boundary
conditions. It is shown that the initial value problem can be solved exactly.
The multi-soliton solution is obtained from the Gel'fand--Levitan--Marchenko
\\ ( ,  25kb)
Paper: cond-mat/0509505
replaced with revised version Mon, 6 Mar 2006 03:38:56 GMT   (232kb)
Title: Quantum atom optics with fermions from molecular dissociation
Authors: K. V. Kheruntsyan
Comments: Changes in response to referees' comments, updated references
Subj-class: Other; Statistical Mechanics
\\ ( ,  232kb)
Paper: cond-mat/0510397
replaced with revised version Mon, 6 Mar 2006 08:56:27 GMT   (81kb)
Title: Observations of density fluctuations in an elongated Bose gas: ideal gas
   and quasi-condensate regimes
Authors: Jerome Esteve (LCFIO), Jean-Baptiste Trebbia (LCFIO), Thorsten Schumm
   (LCFIO), Alain Aspect (LCFIO), Christoph I. Westbrook (LCFIO), Isabelle
   Bouchoule (LCFIO)
Proxy: ccsd ccsd-00011123
Subj-class: Other
\\ ( ,  81kb)
Paper: quant-ph/0603037
Date: Mon, 6 Mar 2006 07:05:49 GMT   (19kb)
Title: Bright entanglement in the intracavity nonlinear coupler
Authors: M.K. Olsen
Comments: 15 pages, 4 figures
   We show that the intracavity Kerr nonlinear coupler is a potential source of
bright continuous variable entangled light beams which are tunable and
spatially separated. This system may be realised with integrated optics and
thus provides a potentially rugged and stable source of bright entangled beams.
\\ ( ,  19kb)
Paper: quant-ph/0603039
Date: Mon, 6 Mar 2006 10:38:52 GMT   (164kb)
Title: Effects of cavity-field statistics on atomic entanglement
Authors: Biplab Ghosh, A. S. Majumdar, N. Nayak
Comments: Revtex, 9 pages, 10 eps figures
   We study the entanglement properties of a pair of two-level atoms going
through a cavity one after another. The initial joint state of two successive
atoms that enter the cavity is unentangled. Interactions mediated by the cavity
photon field result in the final two-atom state being of a mixed entangled
type. We consider respectively various field statistics as in the Fock state
field, thermal field, coherent state field and squeezed state field inside the
cavity, and calculate the entanglement of formation, the well-known measure
appropriate for mixed states, of the joint two-atom state as a function of the
Rabi-angle $gt$. We present a detailed and comparitive study of two-atom
entanglement for low and high mean photon number cases corresponding to the
different cavity fields.
\\ ( ,  164kb)
Paper: quant-ph/0603044
Date: Mon, 6 Mar 2006 15:43:26 GMT   (152kb)
Title: Optical Transparency Using Interference Between Two Modes of a Cavity
Authors: J.D. Franson and S.M. Hendrickson
Comments: 4 pages, 5 figures
   In electromagnetically-induced transparency (EIT), the absorption of a probe
beam is greatly reduced due to destructive interference between two dressed
atomic states produced by a strong laser beam. Here we show that a similar
reduction in the single-photon absorption rate can be achieved by tuning a
probe beam to be halfway between the resonant frequencies of two modes of a
cavity. This technique is expected to be useful in enhancing two-photon
absorption while reducing losses due to single-photon scattering.
\\ ( ,  152kb)
Paper: quant-ph/0603048
Date: Mon, 6 Mar 2006 18:58:42 GMT   (90kb)
Title: Experimental interference of independent photons
Authors: Rainer Kaltenbaek, Bibiane Blauensteiner, Marek Zukowski, Markus
   Aspelmeyer, Anton Zeilinger
Comments: 4 pages, 3 figures
   Interference of photons emerging from independent sources is essential for
modern quantum information processing schemes, above all quantum repeaters and
linear-optics quantum computers. We report an observation of non-classical
interference of two single photons originating from two independent, separated
sources, which were actively synchronized with an r.m.s. timing jitter of 260
fs. The resulting (two-photon) interference visibility was 83(+/-)4 %.
\\ ( ,  90kb)
Paper: quant-ph/0603054
Date: Tue, 7 Mar 2006 16:08:59 GMT   (193kb)
Title: Elastic vs. inelastic coherent backscattering of laser light by cold
   atoms: a master equation treatment
Authors: Vyacheslav Shatokhin, Cord A. M\"uller, Andreas Buchleitner
Comments: 14 pages, 6 figures
   We give a detailed derivation of the master equation description of the
coherent backscattering of laser light by cold atoms. In particular, our
formalism accounts for the nonperturbative nonlinear response of the atoms when
the injected intensity saturates the atomic transition. Explicit expressions
are given for total and elastic backscattering intensities in the different
polarization channels, for the simplest nontrivial multiple scattering scenario
of intense laser light multiply scattering from two randomly placed atoms.
\\ ( ,  193kb)
Paper: cond-mat/0603162
Date: Tue, 7 Mar 2006 12:25:25 GMT   (152kb)
Title: Bose-Fermi mixtures in an optical lattice
Authors: K. Sengupta, N. Dupuis, and P. Majumdar
Comments: 10 pages, 7 figures, version 1
Subj-class: Strongly Correlated Electrons
   We study an atomic Bose-Fermi mixture in an optical lattice which is confined
using an optical trap. We obtain the Mott ground states of such a system in the
limit of deep optical lattice and discuss the effect of quantum fluctuations on
these states. We also study the superfluid-insulator transitions of bosons and
metal-insulator transition of fermions in such a mixture within a slave-rotor
mean-field approximation, and obtain the corresponding phase diagram. We
discuss experimental implications of our results.
\\ ( ,  152kb)
Paper: cond-mat/0410417
replaced with revised version Tue, 7 Mar 2006 09:20:21 GMT   (544kb)
Title: Universality in Few-body Systems with Large Scattering Length
Authors: Eric Braaten (Ohio State U.), H.-W. Hammer (INT and Bonn U.)
Comments: 219 pages, 58 figures, accepted for publication in Physics Reports,
   updated and some errors corrected
Report-no: INT-PUB 04-27, HISKP-TH-06-07
Subj-class: Other; Soft Condensed Matter
\\ ( ,  544kb)
Paper: cond-mat/0510680
replaced with revised version Tue, 7 Mar 2006 17:21:49 GMT   (71kb)
Title: Response of a Fermi gas to time-dependent perturbations: Riemann-Hilbert
   approach at non-zero temperatures
Authors: Bernd Braunecker
Comments: 10 pages, 2 figures; 2 appendices added, a few modifications in the
   text, typos corrected; published in Phys. Rev. B
Subj-class: Strongly Correlated Electrons; Mesoscopic Systems and Quantum Hall
Journal-ref: Phys. Rev. B 73, 075122 (2006)
DOI: 10.1103/PhysRevB.73.075122
\\ ( ,  71kb)
Paper: cond-mat/0603190
Date: Wed, 8 Mar 2006 03:49:58 GMT   (18kb)
Title: Realization, Characterization, and Detection of Novel Superfluid Phases
   with Pairing between Unbalanced Fermion Species
Authors: Kun Yang
Comments: This is an invited contribution to a book titled "Pairing beyond BCS
   Theory in Fermionic Systems" (Mark Alford, John Clark and Armen Sedrakian,
   eds.), to be published by World Scientific. 20 pages
Subj-class: Superconductivity
   In this chapter we review recent experimental and theoretical work on various
novel superfluid phases in fermion systems, that result from pairing fermions
of different species with unequal densities. After briefly reviewing existing
experimental work in superconductors subject to a strong magnetic field and
trapped cold fermionic atom systems, we discuss how to characterize the
possible pairing phases based on their symmetry properties, and the
structure/topology of the Fermi surface(s) formed by the unpaired fermions due
to the density imbalance. We also discuss possible experimental probes that can
be used to directly detect the structure of the superfluid order parameter in
superconductors and trapped cold atom systems, which may establish the presence
of some of these phases unambiguously.
\\ ( ,  18kb)
Paper: cond-mat/0603197
Date: Wed, 8 Mar 2006 09:54:48 GMT   (613kb)
Title: Dark solitons as quasiparticles in trapped condensates
Authors: V.A. Brazhnyi, V.V. Konotop, L.P. Pitaevskii
Comments: 16 pages, 4 figures. To appear in Phys. Rev. A
Subj-class: Other
   We present a theory of dark soliton dynamics in trapped quasi-one-dimensional
Bose-Einstein condensates, which is based on the local density approximation.
The approach is applicable for arbitrary polynomial nonlinearities of the
mean-field equation governing the system as well as to arbitrary polynomial
traps. In particular, we derive a general formula for the frequency of the
soliton oscillations in confining potentials. A special attention is dedicated
to the study of the soliton dynamics in adiabatically varying traps. It is
shown that the dependence of the amplitude of oscillations {\it vs} the trap
frequency (strength) is given by the scaling law $X_0\propto\omega^{-\gamma}$
where the exponent $\gamma$ depends on the type of the two-body interactions,
on the exponent of the polynomial confining potential, on the density of the
condensate and on the initial soliton velocity. Analytical results obtained
within the framework of the local density approximation are compared with the
direct numerical simulations of the dynamics, showing remarkable match. Various
limiting cases are addressed. In particular for the slow solitons we computed a
general formula for the effective mass and for the frequency of oscillations.
\\ ( ,  613kb)
Paper: cond-mat/0603200
Date: Wed, 8 Mar 2006 11:37:19 GMT   (610kb)
Title: Ordered structures in rotating ultracold Bose gases
Authors: N.Barberan, M.Lewenstein, K.Osterloh, and D.Dagnino
Comments: 35 pages, 17 figures
Subj-class: Mesoscopic Systems and Quantum Hall Effect
   The characterization of small samples of cold bosonic atoms in rotating
microtraps has recently attracted increasing interest due to the possibility to
deal with a few number of particles per site in optical lattices. We analyze
the evolution of ground state structures as the rotational frequency $\Omega$
increases. Various kinds of ordered structures are observed. For $N<10$ atoms,
the standard scenario, valid for large sytems, is absent, and only gradually
recovered as $N$ increases. The vortex contribution to the total angular
momentum $L$ as a function of $\Omega$ ceases to be an increasing function of
$\Omega$, as observed in experiments of Chevy {\it et al.} (Phys. Rev. Lett.
85, 2223 (2000)). Instead, for small $N$, it exhibits a sequence of peaks
showing wide minima at the values of $\Omega$, where no vortices appear.
\\ ( ,  610kb)
Paper: cond-mat/0603204
Date: Wed, 8 Mar 2006 13:56:07 GMT   (94kb)
Title: Quantum Dynamics of Atomic Coherence in a Spin-1 Condensate: Mean-Field
   versus Many-Body Simulation
Authors: L.I.Plimak, C.Wei\ss, R.Walser, and W.P.Schleich
Comments: Accepted for publication for the special issue of "Optics
   Communications" on Quantum Control of Light and Matter
Subj-class: Other
   We analyse and numerically simulate the full many-body quantum dynamics of a
spin-1 condensate in the single spatial mode approximation. Initially, the
condensate is in a ``ferromagnetic'' state with all spins aligned along the $y$
axis and the magnetic field pointing along the z axis. In the course of
evolution the spinor condensate undergoes a characteristic change of symmetry,
which in a real experiment could be a signature of spin-mixing many-body
interactions. The results of our simulations are conveniently visualised within
the picture of irreducible tensor operators.
\\ ( ,  94kb)
Paper: cond-mat/0603212
Date: Wed, 8 Mar 2006 15:58:26 GMT   (131kb)
Title: General variational many-body theory with complete self-consistency for
   trapped bosonic systems
Authors: Alexej I. Streltsov, Ofir E. Alon and Lorenz S. Cederbaum
Comments: 53 pages, 8 figures
Subj-class: Other
   In this work we develop a complete variational many-body theory for a system
of $N$ trapped bosons interacting via a general two-body potential. In this
theory both the many-body basis functions {\em and} the respective expansion
coefficients are treated as variational parameters. The optimal variational
parameters are obtained {\em self-consistently} by solving a coupled system of
non-eigenvalue -- generally integro-differential -- equations to get the
one-particle functions and by diagonalizing the secular matrix problem to find
the expansion coefficients. We call this theory multi-configurational Hartree
for bosons or MCHB(M), where M specifies explicitly the number of one-particle
functions used to construct the configurations. General rules for evaluating
the matrix elements of one- and two-particle operators are derived and applied
to construct the secular Hamiltonian matrix. We discuss properties of the
derived equations. It is demonstrated that for any practical computation where
the configurational space is restricted, the description of trapped bosonic
systems strongly depends on the choice of the many-body basis set used, i.e.,
self-consistency is of great relevance. As illustrative examples we consider
bosonic systems trapped in one- and two-dimensional symmetric and asymmetric
double-well potentials. We demonstrate that self-consistency has great impact
on the predicted physical properties of the ground and excited states and show
that the lack of self-consistency may lead to physically wrong predictions. The
convergence of the general MCHB(M) scheme with a growing number M is validated
in a specific case of two bosons trapped in a symmetric double-well.
\\ ( ,  131kb)
Paper: quant-ph/0603063
Date: Wed, 8 Mar 2006 09:50:25 GMT   (176kb)
Title: Matter-wave diffraction in time with a linear potential
Authors: A. del Campo, J. G. Muga
Comments: 11 pages, 6 figures
   Diffraction in time of matter waves incident on a shutter which is removed at
time $t=0$ is studied in the presence of a linear potential. The solution is
also discussed in phase space in terms of the Wigner function. An alternative
configuration relevant to current experiments where particles are released from
a hard wall trap is also analyzed for single-particle states and for a
Tonks-Girardeau gas.
\\ ( ,  176kb)
Paper: cond-mat/0603264
Date: Thu, 9 Mar 2006 19:39:10 GMT   (24kb)
Title: BCS-BEC crossover and quantum phase transition for 6Li and 40K atoms
   across Feshbach resonance
Authors: W. Yi and L.-M. Duan
Comments: 7 pages, 6 figures
Subj-class: Other
   We systematically study the BCS-BEC crossover and the quantum phase
transition in ultracold 6Li and 40K atoms across a wide Feshbach resonance. The
background scattering lengths for 6Li and 40K have opposite signs, which lead
to very different behaviors for these two types of atoms. For 40K, both the
two-body and the many-body calculations show that the system always has two
branches of solutions: one corresponds to a deeply bound molecule state; and
the other, the one accessed by the current experiments, corresponds to a weakly
bound state with population always dominantly in the open channel. For 6Li,
there is only a unique solution with the standard crossover from the weakly
bound Cooper pairs to the deeply bound molecules as one sweeps the magnetic
field through the crossover region. Because of this difference, for the
experimentally accessible state of 40K, there is a quantum phase transition at
zero temperature from the superfluid to the normal fermi gas at the positive
detuning of the magnetic field where the s-wave scattering length passes its
zero point. For 6Li, however, the system changes continuously across the zero
point of the scattering length. For both types of atoms, we also give detailed
comparison between the results from the two-channel and the single-channel
model over the whole region of the magnetic field detuning.
\\ ( ,  24kb)
Paper: cond-mat/0603270
Date: Thu, 9 Mar 2006 20:52:35 GMT   (844kb)
Title: Dressed-molecules in resonantly-interacting ultracold atomic Fermi gases
Authors: G.M. Falco, H.T.C. Stoof
Comments: 44 pages, 24 figures
Subj-class: Other; Superconductivity
   We present a detailed analysis of the two-channel atom-molecule effective
Hamiltonian for an ultracold two-component homogeneous Fermi gas interacting
near a Feshbach resonance. We particularly focus on the two-body and many-body
properties of the dressed molecules in such a gas. An exact result for the
many-body T-matrix of the two-channel theory is derived by both considering
coupled vertex equations and the functional integral methods. The field theory
incorporates exactly the two-body physics of the Feshbach scattering by means
of simple analytical formulas without any fitting parameters. New interesting
many-body effects are discussed in the case of narrow resonances. We give also
a description of the BEC-BCS crossover above and below T_C. The effects of
different approximations for the selfenergy of the dressed molecules are
discussed. The single-channel results are derived as a special limit for broad
resonances. Moreover, through an analytic analysis of the BEC limit, the
relation between the composite boson of the single-channel model and the
dressed-molecule of the two-channel model is established.
\\ ( ,  844kb)
Paper: cond-mat/0510567
replaced with revised version Thu, 9 Mar 2006 09:33:45 GMT   (502kb)
Title: Thermometry of Fermionic Atoms in an Optical Lattice
Authors: Michael K\"ohl
Comments: 4 pages
Subj-class: Strongly Correlated Electrons
Journal-ref: Phys. Rev. A 73, 031601(R) (2006)
DOI: 10.1103/PhysRevA.73.031601
\\ ( ,  502kb)
Paper: cond-mat/0511080
replaced with revised version Thu, 9 Mar 2006 11:58:43 GMT   (282kb)
Title: Probing number squeezing of ultracold atoms across the superfluid-Mott
   insulator transition
Authors: Fabrice Gerbier, Simon Foelling, Artur Widera, Olaf Mandel, Immanuel
Comments: 4 pages; 4 figures
Subj-class: Other
Journal-ref: Phys. Rev. Lett. 96, 090401 (2006)
\\ ( ,  282kb)
Received on Mon Mar 13 2006 - 09:17:47 EST

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