Matt's arXiv selection, Monday 29th May 2006.

From: Matthew Davis <>
Date: Mon, 29 May 2006 10:50:52 +1000 (EST)

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On with the abstracts:

Paper: cond-mat/0605506
Date: Sun, 21 May 2006 10:10:24 GMT (519kb)

Title: Many-body effects on adiabatic passage through Feshbach resonances
Authors: I. Tikhonenkov, E. Pazy, Y. B. Band, M. Fleischhauer, and A. Vardi
Comments: 9 pages, 9 figures
Subj-class: Other
Journal-ref: Phys. Rev. A 73, 043605 (2006)
   We theoretically study the dynamics of an adiabatic sweep through a Feshbach
resonance, thereby converting a degenerate quantum gas of fermionic atoms into
a degenerate quantum gas of bosonic dimers. Our analysis relies on a zero
temperature mean-field theory which accurately accounts for initial molecular
quantum fluctuations, triggering the association process. The structure of the
resulting semiclassical phase space is investigated, highlighting the dynamical
instability of the system towards association, for sufficiently small detuning
from resonance. It is shown that this instability significantly modifies the
finite-rate efficiency of the sweep, transforming the single-pair exponential
Landau-Zener behavior of the remnant fraction of atoms Gamma on sweep rate
alpha, into a power-law dependence as the number of atoms increases. The
obtained nonadiabaticity is determined from the interplay of characteristic
time scales for the motion of adiabatic eigenstates and for fast periodic
motion around them. Critical slowing-down of these precessions near the
instability leads to the power-law dependence. A linear power law $Gamma\propto
alpha$ is obtained when the initial molecular fraction is smaller than the 1/N
quantum fluctuations, and a cubic-root power law $Gamma\propto alpha^{1/3}$ is
attained when it is larger. Our mean-field analysis is confirmed by exact
calculations, using Fock-space expansions. Finally, we fit experimental low
temperature Feshbach sweep data with a power-law dependence. While the
agreement with the experimental data is well within experimental error bars,
similar accuracy can be obtained with an exponential fit, making additional
data highly desirable.
\\ ( , 519kb)
Paper: cond-mat/0605507
Date: Sun, 21 May 2006 20:00:01 GMT (768kb)

Title: Fluctuations in Ideal and Interacting Bose-Einstein Condensates: From
   the laser phase transition analogy to squeezed states and Bogoliubov
Authors: Vitaly V. Kocharovsky, Vladimir V. Kocharovsky, Martin Holthaus, C.H.
   Raymond Ooi, Anatoly A. Svidzinsky, Wolfgang Ketterle and Marlan O. Scully
Comments: 78 pages, 19 figures, review article
Subj-class: Statistical Mechanics
Journal-ref: Advances in Atomic, Molecular and Optical Physics v. 53, 291
   We review the phenomenon of equilibrium fluctuations in the number of
condensed atoms in a trap containing N atoms total. We start with a history of
the Bose-Einstein distribution, the Einstein-Uhlenbeck debate concerning the
rounding of the mean number of condensed atoms near a critical temperature, and
a discussion of the relations between statistics of BEC fluctuations in the
grand canonical, canonical, and microcanonical ensembles.
   Next we discuss different approaches capable of providing approximate
analytical results and physical insight into the problem of fluctuations. In
particular, we describe the master equation (similar to the quantum theory of
the laser) and canonical-ensemble quasiparticle approaches which give the most
accurate and physically transparent picture of the BEC fluctuations.
   In the last part we describe condensate fluctuations in the interacting Bose
gas. In particular, we show that the canonical-ensemble quasiparticle approach
works very well for the interacting gases and yields analytical formulas for
the characteristic function and all moments of the condensate fluctuations. In
most cases the ground-state occupation fluctuations are anomalously large and
are not Gaussian even in the thermodynamic limit. We clarify a crossover
between the ideal and weakly-interacting-gas statistics which is governed by a
pair-correlation squeezing mechanism.
\\ ( , 768kb)
Paper: cond-mat/0605508
Date: Sun, 21 May 2006 21:42:00 GMT (190kb)

Title: Inverse Symmetry Breaking in Multi-Scalar Field Theories
Authors: Marcus Benghi Pinto and Rudnei O. Ramos
Comments: 7 pages, 3 figures, talk given at the workshop on Quantum Fields
   Under the Influence of External Conditions, QFEXT05, Barcelona, sep-2005
Subj-class: Other
Journal-ref: J. Phys. A39, (2006) 6649-6655
   We review how the phenomena of inverse symmetry breaking (and symmetry
nonrestoration) may arise in the context of relativistic as well as
nonrelativistic multi-scalar field theories. We discuss how the consideration
of thermal effects on the couplings produce different transition patterns for
both theories. For the relativistic case, these effects allow the appearance of
inverse symmetry breaking (and symmetry nonrestoration) at arbitrarily large
temperatures. On the other hand, the same phenomena are suppressed in the
nonrelativistic case, which is relevant for condensed matter physics. In this
case, symmetry nonrestoration does not happen while inverse symmetry is allowed
only to be followed by symmetry restoration characterizing a reentrant phase.
The aim of this paper is to give more insight concerning the, qualitatively
correct, results obtained by using one loop perturbation theory in the
evaluation of thermal masses and couplings.
\\ ( , 190kb)
Paper: cond-mat/0605509
Date: Mon, 22 May 2006 03:51:56 GMT (68kb)

Title: Spin current and shot noise from a quantum dot coupled to a quantized
   cavity field
Authors: Ivana Djuric and Chris P. Search
Subj-class: Other
   We examine the spin current and the associated shot noise generated in a
quantum dot connected to normal leads with zero bias voltage across the dot.
The spin current is generated by spin flip transitions induced by a quantized
electromagnetic field inside a cavity with one of the Zeeman states lying below
the Fermi level of the leads and the other above. In the limit of strong
Coulomb blockade, this model is analogous to the Jaynes-Cummings model in
quantum optics. We also calculate the photon current and photon current shot
noise resulting from photons leaking out of the cavity. We show that the photon
current is equal to the spin current and that the spin current can be
significantly larger than for the case of a classical driving field as a result
of cavity losses. In addition to this, the frequency dependent spin (photon)
current shot noise show dips (peaks) that are a result of the discrete nature
of photons.
\\ ( , 68kb)
Paper: cond-mat/0605513
Date: Mon, 22 May 2006 09:54:35 GMT (10kb)

Title: Many-body wavefunctions for normal liquid $^3$He
Authors: Markus Holzmann, Bernard Bernu, D. M. Ceperley
Comments: 4 pages
Subj-class: Strongly Correlated Electrons; Statistical Mechanics
   We present new trial wave-functions which include 3-body correlations into
the backflow coordinates and a 4-body symmetric potential. We show that our
wavefunctions lower the energy enough to stabilize the ground state energies of
normal liquid $^3$He in the unpolarized state at all pressures in agreement
with experiment; however, quantitative discrepancies remain. Further, we
include strong spin coupling into the Fermi liquid by adapting pairing wave
functions. We demonstrate a new, numerically stable method to evaluate pairing
functions which is also useful for Path Integrals calculations at low, but
non-zero temperatures.
\\ ( , 10kb)
Paper: cond-mat/0410287
replaced with revised version Mon, 22 May 2006 13:04:24 GMT (449kb)

Title: The Gross-Pitaevskii equations and beyond for inhomogeneous condensed
Authors: G. G. N. Angilella, S. Bartalini, F. S. Cataliotti, I. Herrera, N. H.
   March, R. Pucci
Comments: To appear in "Trends in Boson Research", edited by A. V. Ling (Nova
   Science, New York, ISBN 1594545219). Better quality figures available upon
Subj-class: Soft Condensed Matter
\\ ( , 449kb)
Paper: quant-ph/0605190
Date: Mon, 22 May 2006 10:54:05 GMT (838kb)

Title: Quantum Computing Using Crossed Atomic Beams
Authors: P. Blythe, B. Varcoe
Comments: 13 pages, 3 figures. PACS: 32.80.Qk, 42.50.Pq, 03.67.Lx
   A quantum computer is a hypothetical device in which the laws of quantum
mechanics are used to introduce a degree of parallelism into computations and
which could therefore significantly improve on the computational speed of a
classical computer at certain tasks. Cluster state quantum computing (recently
proposed by Raussendorf and Briegel) is a new paradigm in quantum information
processing and is a departure from the conventional model of quantum
computation. The cluster state quantum computer begins by creating a highly
entangled multi-particle state (the cluster state) which it uses as a quantum
resource during the computation. Information is processed in the computer via
selected measurements on individual qubits that form the cluster state. We
describe in detail how a scalable quantum computer can be constructed using
microwave cavity QED and, in a departure from the traditional understanding of
a computer as a fixed array of computational elements, we show that cluster
state quantum computing is well suited to atomic beam experiments. We show that
all of the necessary elements have been individually realised, and that the
construction of a truly scalable atomic beam quantum computer may be an
experimental reality in the near future.
\\ ( , 838kb)
Paper: quant-ph/0605191
Date: Mon, 22 May 2006 12:06:26 GMT (146kb)

Title: Atomic entanglement mediated by a squeezed cavity field
Authors: Biplab Ghosh, A. S. Majumdar, N. Nayak
Comments: 6 pages, 7 eps figures
   We consider the coherent state radiation field inside a micromaser cavity and
study the entanglement mediated by it on a pair of two level atoms passing
though the cavity one after the other. We then investigate the effects of
squeezing of the cavity field on the atomic entanglement. We compute the
entanglement of formation for the emerging mixed two-atom state and show that
squeezing of the cavity radiation field can increase the atomic entanglement.
\\ ( , 146kb)
Paper: physics/0605176
Date: Mon, 22 May 2006 15:56:17 GMT (284kb)

Title: Phase-dependent light propagation in atomic vapors
Authors: S. Kajari-Schroeder, G. Morigi, S. Franke-Arnold and G.-L. Oppo
Comments: 16 pages, 11 figures
Subj-class: Atomic Physics
   Light propagation in an atomic medium whose coupled electronic levels form a
diamond-configuration exhibits a critical dependence on the input conditions.
In particular, the relative phase of the input fields gives rise to
interference phenomena in the electronic excitation whose interplay with
relaxation processes determines the stationary state. We integrate numerically
the Maxwell-Bloch equations and observe two metastable behaviors for the
relative phase of the propagating fields corresponding to two possible
interference phenomena. These phenomena are associated to separate types of
response along propagation, minimize dissipation, and are due to atomic
coherence. These behaviors could be studied in gases of isotopes of
alkali-earth atoms with zero nuclear spin, and offer new perspectives in
control techniques in quantum electronics.
\\ ( , 284kb)
Paper : cond-mat/0506415
replaced with revised version Tue, 23 May 2006 18:36:54 GMT (74kb)

Title: Cold Atom Optical Lattices as Quantum Analog Simulators for Aperiodic
   One-Dimensional Localization Without Disorder
Authors: V.W. Scarola and S. Das Sarma
Subj-class: Other; Atomic Physics
Journal-ref: Phys. Rev. A 73, 041609(R) (2006)
\\ ( , 74kb)
Paper: cond-mat/0605550
Date: Tue, 23 May 2006 03:42:20 GMT (127kb)

Title: Fermion nodes and nodal cells of noninteracting and interacting fermions
Authors: Lubos Mitas
Comments: 17 pages, 10 figures
Subj-class: Other; Strongly Correlated Electrons
   A fermion node is subset of fermionic configurations for which a real wave
function vanishes due to the antisymmetry and the node divides the
configurations space into compact nodal cells (domains). We analyze the
properties of fermion nodes of fermionic ground state wave functions for a
number of systems. For several models we demonstrate that noninteracting
spin-polarized fermions in dimension two and higher have closed-shell ground
state wave functions with the minimal two nodal cells for any system size and
we formulate a theorem which sumarizes this result. The models include periodic
fermion gas, fermions on the surface of a sphere, fermions in a box. We prove
the same property for atomic states with up to 3d half-filled shells. Under
rather general assumptions we then derive that the same is true for unpolarized
systems with arbitrarily weak interactions using Bardeen-Cooper-Schrieffer
(BCS) variational wave function. We further show that pair correlations
included in the BCS wave function enable singlet pairs of particles to wind
around the periodic box without crossing the node pointing towards the
relationship of nodes to transport and many-body phases such as
superconductivity. Finally, we point out that the arguments extend also to
fermionic temperature dependent/imaginary-time density matrices. The results
reveal fundamental properties of fermion nodal structures and provide new
insights for accurate constructions of wave functions and density matrices in
quantum and path integral Monte Carlo methods.
\\ ( , 127kb)
Paper: cond-mat/0605554
Date: Tue, 23 May 2006 09:22:27 GMT (52kb)

Title: Dark stationary matter-waves via parity-selective evaporation in a
   Tonks-Girardeau gas
Authors: H. Buljan, O. Manela, R. Pezer, A. Vardi, and M. Segev
Comments: 4 pages, 1 figure
Subj-class: Other
   We propose a scheme for observing dark stationary waves in a Tonks-Girardeau
(TG) gas. The scheme is based on parity-selective dynamical "evaporation" of
the gas via a time-dependent potential, which excites the gas from its ground
state towards a desired specially-tailored many-body state. These excitations
of the TG gas are analogous to linear partially coherent nondiffracting beams
in optics, as evident from the mapping between the quantum dynamics of the TG
gas and the propagation of incoherent light in one-dimensional linear photonic
\\ ( , 52kb)
Paper: cond-mat/0605571
Date: Tue, 23 May 2006 13:19:44 GMT (36kb)

Title: Phases of the polar spin-1 Bose gas in magnetic field
Authors: Krisztian Kis-Szabo, Peter Szepfalusy, Gergely Szirmai
Comments: 5 pages, 1 figure
Subj-class: Other
   We study different properties of the phases originating from the polar phase
of a Bose--Einstein condensed spin-1 gas when a magnetic field is switched on.
Within the Green's function approach generalized Hugenholtz--Pines theorems are
presented, which ensure the existence of gapless Goldstone modes, whose number
is shown to reflect the number of independent phase fluctuations of the complex
order parameter. Crossover to a quantum phase transition when the temperature
goes to zero is also studied. Detailed calculations are presented in a
generalized mean field approximation.
\\ ( , 36kb)
Paper: cond-mat/0506371
replaced with revised version Tue, 23 May 2006 14:46:05 GMT (134kb)

Title: Localization of Matter Waves in 2D-Disordered Optical Potentials
Authors: R. C. Kuhn, C. Miniatura, D. Delande, O. Sigwarth and C. A. Mueller
Comments: 4 pages, 3 figures, figures changed, references updated
Subj-class: Mesoscopic Systems and Quantum Hall Effect
Journal-ref: Phys. Rev. Lett. 95, 250403 (2005)
DOI: 10.1103/PhysRevLett.95.250403
\\ ( , 134kb)
Paper: cond-mat/0512243
replaced with revised version Tue, 23 May 2006 13:20:09 GMT (217kb)

Title: Phase diagram of Bose-Fermi mixtures in one-dimensional optical lattices
Authors: Lode Pollet, Matthias Troyer, Kris Van Houcke, Stefan M. A. Rombouts
Comments: 5 pages, 5 figures, replaced with published version
Subj-class: Statistical Mechanics
Journal-ref: Phys. Rev. Lett. 96, 190402 (2006)
\\ ( , 217kb)
Paper: cond-mat/0603332
replaced with revised version Tue, 23 May 2006 00:21:00 GMT (410kb)

Title: Mean field phase diagrams of imbalanced Fermi gases near a Feshbach
Authors: Hui Hu and Xia-Ji Liu
Comments: 4 pages + 5 figures, references updated, Published verison in Phys.
   Rev. A as a Rapid Communication
Subj-class: Strongly Correlated Electrons; Superconductivity
Journal-ref: Phys. Rev. A 73, 051603 (R) (2006)
DOI: 10.1103/PhysRevA.73.051603
\\ ( , 410kb)
Paper: cond-mat/0603571
replaced with revised version Tue, 23 May 2006 16:01:22 GMT (90kb)

Title: Identifying the Bose glass phase
Authors: R. Pugatch, N. Bar-gill, N. Katz, E. Rowen, N. Davidson
Comments: 4 pages, 3 figures (corrected and expanded bibliography)
Subj-class: Soft Condensed Matter; Other
\\ ( , 90kb)
Paper: cond-mat/0605102
replaced with revised version Tue, 23 May 2006 16:45:14 GMT (243kb)

Title: Topological defects and the superfluid transition of the $s=1$ spinor
   condensate in two dimensions
Authors: Subroto Mukerjee, Cenke Xu, and J. E. Moore
Comments: 4 pages, 2 figures; corrected references
Subj-class: Other
\\ ( , 243kb)
Paper: physics/0605200
Date: Tue, 23 May 2006 17:01:52 GMT (401kb)

Title: An accurate optical lattice clock with 87Sr atoms
Authors: Rodolphe Le Targat (SYRTE), Xavier Baillard (SYRTE), Mathilde
   Fouch\'{e} (SYRTE), Anders Brusch (SYRTE), Olivier Tcherbakoff (SYRTE),
   Giovanni D. Rovera (SYRTE), Pierre Lemonde (SYRTE)
Proxy: ccsd ccsd-00071833
Subj-class: Atomic Physics
   We report a frequency measurement of the 1S0-3P0 transition of 87Sr atoms in
an optical lattice clock. The frequency is determined to be 429 228 004 229 879
(5) Hz with a fractional uncertainty that is comparable to state-of-the-art
optical clocks with neutral atoms in free fall. Two previous measurements of
this transition were found to disagree by about 2x10^{-13}, i.e. almost four
times the combined error bar, instilling doubt on the potential of optical
lattice clocks to perform at a high accuracy level. In perfect agreement with
one of these two values, our measurement essentially dissipates this doubt.
\\ ( , 401kb)
Paper: cond-mat/0605581
Date: Tue, 23 May 2006 21:08:29 GMT (23kb)

Title: Response to Comment on "Pairing and Phase Separation in a Polarized
   Fermi Gas"
Authors: Guthrie B. Partridge, Wenhui Li, Ramsey I. Kamar, Yean-An Liao, and
   Randall G. Hulet
Comments: This is a response to version 1 of the Comment (cond-mat/0603489 v1).
   This version of the Comment was submitted to and rejected by Science
Subj-class: Superconductivity; Strongly Correlated Electrons
   In their comment, Zwierlein and Ketterle contend that features observed in
real-space distributions recorded in our experiment are an artifact of an
anharmonic trapping potential. We show that Zwierlein and Ketterle have grossly
overestimated these effects, and that anharmonicities can neither
quantitatively nor qualitatively reproduce the observed distributions.
\\ ( , 23kb)
Paper: cond-mat/0605597
Date: Wed, 24 May 2006 13:01:29 GMT (95kb)

Title: Classical simulation of infinite-size quantum lattice systems in one
   spatial dimension
Authors: G. Vidal
Comments: 5 pages, 6 figures
Subj-class: Strongly Correlated Electrons
   We show how translational invariance can be exploited to efficiently simulate
one-dimensional quantum lattice systems in the limit of an infinite lattice.
Both the computation of the ground state and the simulation of time evolution
are considered.
\\ ( , 95kb)
Paper: cond-mat/0605603
Date: Wed, 24 May 2006 15:09:19 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: 3 pages
Subj-class: Other
   We prove the finite-time collapse of a system of N classical fields, which
are described by N coupled nonlinear Schrodinger equations. We derive the
conditions under which all of the fields experiences this finite-time collapse.
Finally, for two-dimensional systems, we derive constraints on the number of
particles associated with each field that are necessary to prevent collapse.
\\ ( , 5kb)
Paper: cond-mat/0605604
Date: Wed, 24 May 2006 15:14:29 GMT (61kb)

Title: pi-Josephson junction and spontaneous superflow in rings from ultracold
   fermionic gases
Authors: Miodrag Kulic
Comments: 6 pages, 3 figures
Subj-class: Statistical Mechanics; Strongly Correlated Electrons
   The BCS like pairing in ultracold fermionic gases is studied in the model of
"isotopic-spin" pairing which is proposed in 1991. This model assumes a
mismatch $\delta $ in energies (chemical potentials) of pairing fermionic
atoms. In case when $\delta >\delta_{c1}$ at T=0 $K$, and $\delta >\delta
^{\ast}$ at $T<T^{\ast}$, the nonuniform (LOFF-like) superfluid state is
realized with the oscillating order parameter. It is shown that the $\pi
$-Josephson junction can be realized in $SMS$ systems, where the left and right
banks $S$ are neutral ultracold fermionic superfluids. The weak link $M$ is
made from the normal ultracold fermionic gas (also neutral) with the finite
mismatch $\delta $. If such a $\pi $% -junction is a part of the closed ring
there is a spontaneous breaking of time-reversal symmetry and spontaneous
superfluid mass-current flows in the ring. This is realized if the radius of
the ring $R$ is larger than the critical one $R_{c}$. All these effects exist
also in the case when $\delta \gg \Delta $, where $\Delta $ is the superfluid
gap, but with the reduced thickness of the weak link.
   It is discussed also, that if junctions such as $SM_{1}M_{2}S$ and trilayers
$% M_{1}SM_{2}$ are realizable in ultracold fermionic atomic gases, they could
open a way for a new kind of electronics - \textit{hypertronics}.
\\ ( , 61kb)
Paper: cond-mat/0605607
Date: Wed, 24 May 2006 18:31:34 GMT (217kb)

Title: A superfluid 4He interferometer operating near 2 K
Authors: Emile Hoskinson, Yuki Sato, and Richard Packard
Comments: 8 pages, 2 figures
Subj-class: Superconductivity
   Matter-wave interferometers reveal some of the most fascinating phenomena of
the quantum world. Phase shifts due to rotation (the Sagnac effect) for
neutrons, free atoms and superfluid 3He reveal the connection of matter waves
to a non-rotating inertial frame. In addition, phase shifts in electron waves
due to magnetic vector potentials (the Aharonov-Bohm effect) show that physical
states can be modified in the absence of classical forces. We report here the
observation of interference induced by the Earth's rotation in superfluid 4He
at 2 K, a temperature 2000 times higher than previously achieved with 3He. This
interferometer, an analog of a dc-SQUID, employs a recently reported phenomenon
wherein superfluid 4He exhibits quantum oscillations in an array of sub-micron
apertures. We find that the interference pattern persists not only when the
aperture array current-phase relation is a sinusoidal function characteristic
of the Josephson effect, but also at lower temperatures where it is linear and
oscillations occur by phase slips. The modest requirements for the
interferometer (2 K cryogenics and fabrication of apertures at the level of
100nm) and its potential resolution suggest that, when engineering challenges
such as vibration isolation are met, superfluid 4He interferometers could
become important scientific probes.
\\ ( , 217kb)
Paper: cond-mat/0508195
replaced with revised version Wed, 24 May 2006 16:08:04 GMT (93kb)

Title: Velocity of vortices in inhomogeneous Bose-Einstein condensates
Authors: Halvor M. Nilsen, Gordon Baym, and C. J. Pethick
Comments: 5 pages, one .eps figure. Published version
Report-no: NORDITA-2005-51
Subj-class: Other
Journal-ref: Proc. Natl. Acad. Sci. 103, 7978 (2006)
\\ ( , 93kb)
Paper: cond-mat/0510750
replaced with revised version Wed, 24 May 2006 10:30:54 GMT (34kb)

Title: Explicit expressions for the topological defects of spinor Bose-Einstein
Authors: H. M\"akel\"a
Comments: 17 pages, partly rewritten to improve clarity, conclusions unchanged
Subj-class: Other
Journal-ref: J. Phys. A: Math. Gen. 39, 7423 (2006)
\\ ( , 34kb)
Paper: cond-mat/0601681
replaced with revised version Wed, 24 May 2006 17:18:29 GMT (226kb)

Title: Exact Study of the 1D Boson Hubbard Model with a Superlattice Potential
Authors: V.G. Rousseau, D.P. Arovas M. Rigol, F. H\'ebert, G.G. Batrouni, R.T.
Comments: 12 pages, 22 figures
Subj-class: Other; Strongly Correlated Electrons
Journal-ref: Physical Review B 73, 174516 (2006)
DOI: 10.1103/PhysRevB.73.174516
\\ ( , 226kb)
Paper: cond-mat/0603498
replaced with revised version Wed, 24 May 2006 06:00:43 GMT (682kb)

Title: Pairing in a three component Fermi gas
Authors: T. Paananen, J.-P. Martikainen, and P. Torma
Comments: 10 pages, 3 figures
Subj-class: Superconductivity
Journal-ref: Phys. Rev. A 73, 053606 (2006)
\\ ( , 682kb)
Paper: cond-mat/0604232
replaced with revised version Wed, 24 May 2006 09:39:08 GMT (346kb)

Title: Three-dimensional strong localization of matter waves by scattering from
   atoms in a lattice with a confinement-induced resonance
Authors: Pietro Massignan (LKB - Lhomond), Yvan Castin (LKB - Lhomond)
Comments: 21 pages; 14 figures
Proxy: ccsd ccsd-00022452
Subj-class: Disordered Systems and Neural Networks
\\ ( , 346kb)
Paper: quant-ph/0605202
Date: Tue, 23 May 2006 22:37:44 GMT (21kb)

Title: Adiabatic Condition for Nonlinear Systems
Authors: Han Pu, Peter Maenner, Weiping Zhang, and Hong Y. Ling
Comments: 4 pages, 3 figures
   We revisit the adiabatic criterion in stimulated Raman adiabatic passage for
the three-level $\Lambda$-system, and compare the situation with and without
nonlinearity. In linear systems, the adiabatic condition is derived with the
help of the instantaneous eigenvalues and eigenstates of the Hamiltonian, a
procedure that breaks down in the presence of nonlinearity. Using an explicit
example relevant to photoassociation of atoms into diatomic molecules, we
demonstrate that the proper way to derive the adiabatic condition for the
nonlinear systems is through a linearization procedure.
\\ ( , 21kb)
Paper: quant-ph/0605210
Date: Wed, 24 May 2006 14:20:11 GMT (390kb)

Title: Ultracold Few-Boson Systems in a Double-Well Trap
Authors: Sascha Z\"ollner, Hans-Dieter Meyer, and Peter Schmelcher
   We investigate the transition of a quasi-one-dimensional few-boson system
from a weakly correlated to a fragmented and finally a fermionized ground
state. Our numerically exact analysis, based on a multi-configurational method,
explores the interplay between different shapes of external and inter-particle
forces. Specifically, we demonstrate that the addition of a central barrier to
an otherwise harmonic trap may supports the system's fragmentation, with a
symmetry-induced distinction between even and odd atom numbers. Moreover, the
impact of inhomogeneous interactions is studied, where the effective coupling
strength is spatially modulated. It is laid out how the ground state can be
displaced in a controlled way depending on the trap and the degree of
modulation. We present the one- and two-body densities and, beyond that,
highlight the role of correlations on the basis of the natural occupations.
\\ ( , 390kb)
Paper: cond-mat/0605616
Date: Thu, 25 May 2006 01:25:22 GMT (61kb)

Title: Pi-Josephson junction and spontaneous superflow in rings from ultracold
   fermionic atomic gases
Authors: Miodrag L. Kulic
Comments: 6 pages, 3 figures
Subj-class: Superconductivity; Soft Condensed Matter
   The BCS like pairing in ultracold fermionic gases is studied in the model of
"isotopic-spin" pairing which is proposed in 1991 by the present author and his
collaborator. This model assumes a mismatch \delta in energies (chemical
potentials) of pairing fermionic atoms. In case when \delta >\delta_{c1} at T=0
K, and \delta >\delta ^{\ast} at T<T^{\ast}, the nonuniform (LOFF-like)
superfluid state is realized with the oscillating order parameter. It is shown
that the pi-Josephson junction can be realized in SMS systems, where the left
and right banks S are neutral ultracold fermionic superfluids. The weak link
$M$ is made from the normal ultracold fermionic gas (also neutral) with the
finite mismatch \delta. If such a pi-junction is a part of the closed ring
there is a spontaneous breaking of time-reversal symmetry and spontaneous
superfluid mass-current flows in the ring. This is realized if the radius of
the ring R is larger than the critical one R_{c}. All these effects exist also
in the case when \delta >>\Delta, where \Delta is the superfluid gap, but with
the reduced thickness of the weak link.
   It is discussed also, that if junctions such as SM_{1}M_{2}S and trilayers
M_{1}SM_{2} are realizable in ultracold fermionic atomic gases, they could open
a way for a new kind of electronics - hypertronics.
\\ ( , 61kb)
Paper: cond-mat/0605622
Date: Thu, 25 May 2006 09:30:53 GMT (261kb)

Title: Discrete breathers in BEC with two- and three-body interactions in
   optical lattice
Authors: F.Kh. Abdullaev, A. Bouketir, A. Messikh, B.A. Umarov
Comments: 10 pages, 10 figures
Subj-class: Other
   We investigate the properties of discrete breathers in a Bose-Einstein
condensate with two- and three-body interactions in optical lattice. In the
tight-binding approximation the Gross-Pitaevskii equation with periodic
potential for the condensate wavefunction is reduced to the cubic-quintic
discrete nonlinear Schr\"odinger equation. We analyze the regions of
modulational instabilities of nonlinear plane waves. This result is important
to obtain the conditions for generation of discrete solitons(breathers) in
optical lattice. Also using the Page approach, we derive the conditions for the
existence and stability for bright discrete breather solutions. It is shown
that the quintic nonlinearity brings qualitatively new conditions for stability
of strongly localized modes. The numerical simulations conform with the
analytical predictions.
\\ ( , 261kb)
Paper: physics/0605225
Date: Thu, 25 May 2006 15:27:16 GMT (70kb)

Title: Worm Algorithm and Diagrammatic Monte Carlo: A New Approach to
   Continuous-Space Path Integral Monte Carlo Simulations
Authors: M. Boninsegni, N. V. Prokof'ev and B. V. Svistunov
Comments: 17 pages, 13 figures
Subj-class: Computational Physics
   A detailed description is provided of a new Worm Algorithm, enabling the
accurate computation of thermodynamic properties of quantum many-body systems
in continuous space, at finite temperature. The algorithm is formulated within
the general Path Integral Monte Carlo (PIMC) scheme, but also allows one to
perform quantum simulations in the grand canonical ensemble, as well as to
compute off-diagonal imaginary-time correlation functions, such as the
Matsubara Green function, simultaneously with diagonal observables. Another
important innovation consists of the expansion of the attractive part of the
pairwise potential energy into elementary (diagrammatic) contributions, which
are then statistically sampled. This affords a complete microscopic account of
the long-range part of the potential energy, while keeping the computational
complexity of all updates independent of the size of the simulated system. The
computational scheme allows for efficient calculations of the superfluid
fraction and off-diagonal correlations in space-time, for system sizes which
are orders of magnitude larger than those accessible to conventional PIMC. We
present illustrative results for the superfluid transition in bulk liquid
helium-four in two and three dimensions, as well as the calculation of the
chemical potential of solid helium-four.
\\ ( , 70kb)
Paper: physics/0509157
replaced with revised version Thu, 25 May 2006 17:10:31 GMT (132kb)

Title: Polarization spectroscopy in rubidium and cesium
Authors: M. L. Harris, C. S. Adams, S. L. Cornish, I. C. McLeod, E. Tarleton
   and I. G. Hughes
Comments: 8 pages, 5 figures, to be published in Phys. Rev. A; figures and
   discussion added
Subj-class: Atomic Physics
\\ ( , 132kb)

Till next 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
Received on Mon May 29 2006 - 10:50:52 EST

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