# Matt's arXiv selection, Tuesday 19th September 2006.

From: Matthew Davis <mdavis_at_physics.uq.edu.au>
Date: Tue, 19 Sep 2006 15:17:34 +1000 (EST)

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

So it seems that I am still running a day late....

The abstracts for the past week:

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Paper: cond-mat/0609212
Date: Fri, 8 Sep 2006 23:53:00 GMT (98kb)

Title: Exotic Superconducting Phases of Ultracold Atom Mixtures on Triangular
Lattices
Authors: L. Mathey, S.-W. Tsai, A.H. Castro Neto
Subj-class: Superconductivity
\\
We study the phase diagram of two-dimensional Bose-Fermi mixtures of
ultracold atoms on a triangular optical lattice, in the limit when the velocity
of bosonic condensate fluctuations is much larger than the Fermi velocity.
Using functional renormalization group techniques we show that this phase
diagram contains exotic superconducting phases. For spin-1/2 fermions on an
isotropic lattice we find a competition of $s$-, $p$-, extended $d$-, and
$f$-wave symmetry, as well as antiferromagnetic order. For an anisotropic
lattice, we further find an extended p-wave phase. A Bose-Fermi mixture with
spinless fermions on an isotropic lattice shows a competition between $p$- and
$f$-wave symmetry.
\\ ( http://arXiv.org/abs/cond-mat/0609212 , 98kb)
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Paper: cond-mat/0609218
Date: Sat, 9 Sep 2006 10:14:48 GMT (15kb)

Title: Quantum tunneling of magnetization in dipolar spin-1 condensates under
external fields
Authors: Limin Yang, Yunbo Zhang
Subj-class: Other
\\
We study the macroscopic quantum tunneling of magnetization of the F=1 spinor
condensate interacting through dipole-dipole interaction with an external
magnetic field applied along the longitudinal or transverse direction. We show
that the ground state energy and the effective magnetic moment of the system
exhibit an interesting macroscopic quantum oscillation phenomenon originating
from the oscillating dependence of thermodynamic properties of the system on
the vacuum angle. Tunneling between two degenerate minima are analyzed by means
of an effective potential method and the periodic instanton method.
\\ ( http://arXiv.org/abs/cond-mat/0609218 , 15kb)
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Paper: cond-mat/0609219
Date: Sat, 9 Sep 2006 10:23:20 GMT (44kb)

Title: Ground-state Competition of Two-Component Bosons in Optical Lattice near
a Feshbach Resonance
Authors: Liping Guo, Yunbo Zhang, Shu Chen
Comments: 2 figures, submitted to PRA
Subj-class: Other
\\
We investigate the ground state properties of an equal mixture of two species
of bosons in its Mott-insulator phase at a filling factor two per site. We
identify one type of spin triplet-singlet transition through the competition of
ground state. When the on-site interaction is weak ($U<U_c$) the two particles
prefer to stay in the lowest band and with weak tunneling between neighboring
sites the system is mapped into an effective spin-1 ferromagnetic exchange
Hamiltonian. When the interaction is tuned by a Feshbach resonance to be large
enough ($U>U_c$), higher band will be populated. Due to the orbital coupling
term $S^+S^-$ in the Hamiltonian, the two atoms in different orbits on a site
would form an on-site singlet.
\\ ( http://arXiv.org/abs/cond-mat/0609219 , 44kb)
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Paper: cond-mat/0609230
Date: Sun, 10 Sep 2006 15:29:53 GMT (210kb)

Title: Finite-temperature effects on the number fluctuation of ultracold atoms
across the Superfluid to Mott-insulator transition
Authors: Xiancong Lu and Yue Yu
Subj-class: Other
\\
We study thermodynamics of ultracold Bose atoms in optical lattice by
numerically diagonalizing the mean-field Hamiltonian of the Bose-Hubbard model.
The advantage of this method to the previous finite-temperature perturbation
theory is its validity deep in the superfluid phase. For the homogeneous
Bose-Hubbard model, we draw the finite-temperature phase diagram and calculate
the superfluid density at unity filling. We evaluate the finite-temperature
effects in a recent experiment probing number fluctuation [Phys. Rev. Lett.
\textbf{96}, 090401 (2006)], and find that our theoretical calculations
including the finite-temperature effects are in good agreement with the
experiment results.
\\ ( http://arXiv.org/abs/cond-mat/0609230 , 210kb)
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Paper: cond-mat/0609240
Date: Mon, 11 Sep 2006 17:14:19 GMT (87kb)

Title: Normal-Superfluid Interface Scattering For Polarized Fermion Gases
Authors: Bert Van Schaeybroeck and Achilleas Lazarides
Subj-class: Other; Superconductivity
\\
The scattering on an interface between a normal (N) and a gapped superfluid
(SF) strongly affects the thermal equilibration process at low temperatures for
fermion gases with population imbalance. Using the Bogoliubov-de Gennes
formalism, we theoretically study the various reflection and transmission
channels for an N-SF interface from the deep BCS to to the unitary regime. We
find that the thermal conductivity drops exponentially fast with increasing
$h/k_B T$, where $h$ is the chemical potential imbalance. It is also argued
that the presence of the interface may, at least at T=0, modify or even cause
the FFLO-like states seen in recent studies.
\\ ( http://arXiv.org/abs/cond-mat/0609240 , 87kb)
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Paper: cond-mat/0609251
Date: Mon, 11 Sep 2006 11:35:54 GMT (9kb)

Title: Collective motions of a quantum gas confined in a harmonic trap
Authors: Dae-Yup Song
Comments: Typos in the printed verions are corrected
Subj-class: Mesoscopic Systems and Quantum Hall Effect; Statistical Mechanics
Journal-ref: Phys. Rev. A 72, 023614 (2005)
DOI: 10.1103/PhysRevA.72.023614
\\
Single-component quantum gas confined in a harmonic potential, but otherwise
isolated, is considered. From the invariance of the system of the gas under a
displacement-type transformation, it is shown that the center of mass
oscillates along a classical trajectory of a harmonic oscillator. It is also
shown that this harmonic motion of the center has, in fact, been implied by
Kohn's theorem. If there is no interaction between the atoms of the gas, the
system in a time-independent isotropic potential of frequency $\nu_c$ is
invariant under a squeeze-type unitary transformation, which gives collective
{\it radial} breathing motion of frequency $2\nu_c$ to the gas. The amplitudes
of the oscillating and breathing motions from the {\it exact} invariances could
be arbitrarily large. For a Fermi system, appearance of $2\nu_c$ mode of the
large breathing motion indicates that there is no interaction between the
atoms, except for a possible long-range interaction through the
inverse-square-type potential.
\\ ( http://arXiv.org/abs/cond-mat/0609251 , 9kb)
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Paper: cond-mat/0609253
Date: Mon, 11 Sep 2006 11:45:04 GMT (8kb)

Title: Exact coherent states of a noninteracting Fermi gas in a harmonic trap
Authors: Dae-Yup Song
Subj-class: Mesoscopic Systems and Quantum Hall Effect
\\
Exact and closed-form expressions of the particle density, the kinetic energy
density, the probability current density, and the momentum distribution are
derived for a coherent state of a noninteracting Fermi gas, while such a state
can be obtained from the ground state in a $d$-dimensional isotropic harmonic
trap by modulating the trap frequency and shifting the trap center.
Conservation laws for the relations of the densities are also given. The
profile of the momentum distribution turns out to be identical in shape with
that of the particle density, however, %as an observable manifestation of the
uncertainty principle, the dispersion of the distribution increases (decreases)
when that of the particle density is decreased (increased). The expressions are
also applicable for a sudden and total opening of the trap, and it is shown
that, after the opening, the gas has a stationary momentum distribution whose
dispersion could be arbitrarily large or small.
\\ ( http://arXiv.org/abs/cond-mat/0609253 , 8kb)
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Paper: cond-mat/0609259
Date: Mon, 11 Sep 2006 19:04:22 GMT (259kb)

Title: Dual-species quantum degeneracy of potassium-40 and rubidium-87 on an
atom chip
Authors: M. H. T. Extavour, L. J. LeBlanc, T. Schumm, B. Cieslak, S. Myrskog,
A. Stummer, S. Aubin, J. H. Thywissen
Comments: 8 pages, 4 figures. To be published in the Proceedings of the 20th
International Conference on Atomic Physics, 2006 (Innsbruck, Austria)
Subj-class: Statistical Mechanics
\\
In this article we review our recent experiments with a 40K-87Rb mixture. We
demonstrate rapid sympathetic cooling of a 40K-87Rb mixture to dual quantum
degeneracy on an atom chip. We also provide details on efficient BEC
production, species-selective magnetic confinement, and progress toward
integration of an optical lattice with an atom chip. The efficiency of our
evaporation allows us to reach dual degeneracy after just 6 s of evaporation -
more rapidly than in conventional magnetic traps. When optimizing evaporative
cooling for efficient evaporation of 87Rb alone we achieve BEC after just 4 s
of evaporation and an 8 s total cycle time.
\\ ( http://arXiv.org/abs/cond-mat/0609259 , 259kb)
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Paper: cond-mat/0604580
replaced with revised version Sat, 9 Sep 2006 08:13:47 GMT (16kb)

Title: Superfluidity in a Three-flavor Fermi Gas with SU(3) Symmetry
Authors: Lianyi He, Meng Jin and Pengfei Zhuang
Comments: 9 pages, 2 figures, published version
Subj-class: Other; Superconductivity; Atomic Physics
Journal-ref: Phys. Rev. A 74, 033604 (2006)
DOI: 10.1103/PhysRevA.74.033604
\\ ( http://arXiv.org/abs/cond-mat/0604580 , 16kb)
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Paper: cond-mat/0606624
replaced with revised version Sun, 10 Sep 2006 02:00:40 GMT (27kb)

Title: Asymmetric two-component Fermi gas with unequal masses
Authors: M. Iskin and C. A. R. Sa de Melo
Comments: 4 pages and 4 figures
Subj-class: Superconductivity; Other
\\ ( http://arXiv.org/abs/cond-mat/0606624 , 27kb)
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Paper: cond-mat/0607542
replaced with revised version Mon, 11 Sep 2006 05:40:43 GMT (25kb)

Title: Analytic solutions of the 1D finite coupli,ng delta function Bose gas
Authors: P. J. Forrester, N. E. Frankel and M. I. Makin
Comments: 23 pages, 0 figures, uses rotate.sty. A few lines added. Accepted by
Phys. Rev. A
Subj-class: Statistical Mechanics; Mathematical Physics
\\ ( http://arXiv.org/abs/cond-mat/0607542 , 25kb)
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Paper: quant-ph/0609077
Date: Mon, 11 Sep 2006 12:35:22 GMT (34kb)

Title: An investigation into why macroscopic systems behave classically
Authors: David W. Hallwood, Keith Burnett, Jacob Dunningham
\\
We study why it is hard to make a macroscopic superposition of superfluid
flows in a Bose-Einstein condensate. Initially we investigate N atoms trapped
in a simple 1D ring with a barrier at one point and a phase applied around it.
Perturbation theory is used to show that quasi-momentum (or flow) macroscopic
superpositions can be made and we investigate factors which affect the cat
state. The 1D ring is improved using the Bose-Hubbard model to study an array
of Bose-Einstein condensates trapped in optical potentials and coupled to one
another to form a ring. We derive an analytic expression to describe the
quality of the cat, which agrees well with direct diagonalisation of the
Hamiltonian for relatively small numbers of atoms. We show that for macroscopic
superposition to be realised there are three factors that are required, other
than an absence of decoherence, which become harder to satisfy when the system
size increases. These are, (1) the energies of the two macroscopic states must
be similar, (2) coupling between the two macroscopic states must be strong, and
(3) other states must not be strongly coupled to the macroscopic states. The
results help us to understand quantum mechanics on a macroscopic level.
\\ ( http://arXiv.org/abs/quant-ph/0609077 , 34kb)
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Paper: cond-mat/0609290
Date: Tue, 12 Sep 2006 16:07:30 GMT (83kb)

Title: Renormalized atomic interaction and quadrupole excitations of cold Fermi
gas near Feshbach resonance
Authors: Lai-Wa Siu, T. T. S. Kuo, B. A. Gelman
Subj-class: Other
\\
We present a model space particle-hole Green's function calculation for the
quadrupole excitations of cold Fermi gas near Feshbach resonance using a simple
model where atoms are confined in a harmonic oscillator potential. Both the
Tamm-Dancoff and random phase approximations are employed. By summing up
exactly the ladder diagrams between a pair of interacting atoms to all orders,
we obtain a renormalized atomic interaction which has well defined and
identical limits as the scattering length tends to $\pm \infty$. The
experimentally observed abrupt rise in the excitation spectrum and its
associated large decay width are satisfactorily reproduced by our calculation.
\\ ( http://arXiv.org/abs/cond-mat/0609290 , 83kb)
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Paper: quant-ph/0609095
Date: Tue, 12 Sep 2006 16:23:58 GMT (331kb)

Title: Optical signatures of quantum phase transitions in a light-matter system
Authors: Timothy C. Jarrett, Alexandra Olaya-Castro and Neil F. Johnson
\\
Information about quantum phase transitions in conventional condensed matter
systems, must be sought by probing the matter system itself. By contrast, we
show that mixed matter-light systems offer a distinct advantage in that the
photon field carries clear signatures of the associated quantum critical
phenomena. Having derived an accurate, size-consistent Hamiltonian for the
photonic field in the well-known Dicke model, we predict striking behavior of
the optical squeezing and photon statistics near the phase transition. The
corresponding dynamics resemble those of a degenerate parametric amplifier. Our
findings boost the motivation for exploring exotic quantum phase transition
phenomena in atom-cavity, nanostructure-cavity, and
nanostructure-photonic-band-gap systems.
\\ ( http://arXiv.org/abs/quant-ph/0609095 , 331kb)
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Paper: quant-ph/0603156
replaced with revised version Tue, 12 Sep 2006 04:24:25 GMT (22kb)

Title: Implementing the one-dimensional quantum (Hadamard) walk using a
Bose-Einstein Condensate
Authors: C.M. Chandrashekar
Journal-ref: Phys. Rev. A . 74, 032307 (2006)
\\ ( http://arXiv.org/abs/quant-ph/0603156 , 22kb)
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Paper: cond-mat/0609307
Date: Wed, 13 Sep 2006 05:17:04 GMT (220kb)

Title: Hidden order in one dimensional Bose insulators
Authors: Emanuele G. Dalla Torre, Erez Berg, Ehud Altman
Subj-class: Other; Strongly Correlated Electrons
\\
We investigate the phase diagram of spinless bosons with long range (~ 1/r^3)
repulsive interactions, relevant to ultracold polarized atoms or molecules,
using DMRG. Between the two conventional insulating phases, the Mott and
density wave phases, we find a new phase possessing hidden order revealed by
non local string correlations analogous to those characterizing the Haldane
gapped phase of integer spin chains. We develop a mean field theory that
describes the low energy excitations in all three insulating phases. This is
used to calculate the absorption spectrum due to oscillatory lattice
modulation. We predict a sharp resonance in the spectrum due to a collective
excitation of the new phase that would provide clear evidence for the existence
of this phase.
\\ ( http://arXiv.org/abs/cond-mat/0609307 , 220kb)
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Paper: cond-mat/0609313
Date: Wed, 13 Sep 2006 08:34:56 GMT (70kb)

Title: Dynamically stable multiply quantized vortices in dilute Bose-Einstein
condensates
Authors: J. A. M. Huhtam\"aki (1), M. M\"ott\"onen (1 and 2) and S. M. M.
Virtanen (1)
Subj-class: Statistical Mechanics
\\
Multiquantum vortices in dilute atomic Bose-Einstein condensates confined in
long cigar-shaped traps are known to be both energetically and dynamically
unstable. They tend to split into single-quantum vortices even in the ultralow
temperature limit with vanishingly weak dissipation, which has also been
confirmed in the recent experiments [Y. Shin et al., Phys. Rev. Lett. 93,
160406 (2004)] utilizing the so-called topological phase engineering method to
create multiquantum vortices. We study the stability properties of multiquantum
vortices in different trap geometries by solving the Bogoliubov excitation
spectra for such states. We find that there are regions in the trap asymmetry
and condensate interaction strength plane in which the splitting instability of
multiquantum vortices is suppressed, and hence they are dynamically stable. For
example, the doubly quantized vortex can be made dynamically stable even in
spherical traps within a wide range of interaction strength values. We expect
that this suppression of vortex-splitting instability can be experimentally
verified.
\\ ( http://arXiv.org/abs/cond-mat/0609313 , 70kb)
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Paper (*cross-listing*): nlin.PS/0609032
Date: Tue, 12 Sep 2006 15:39:15 GMT (213kb)

Title: Fano blockade by a Bose-Einstein condensate in an optical lattice
Authors: Rodrigo A. Vicencio, Joachim Brand, and Sergej Flach
Comments: 4 pages, 4 figures (fig4 was resized for arXiv)
Subj-class: Pattern Formation and Solitons; Other
\\
We study the transport of atoms across a localized Bose-Einstein condensate
in a one-dimensional optical lattice. For atoms scattering off the condensate
we predict total reflection as well as full transmission for certain parameter
values on the basis of an exactly solvable model. The findings of analytical
and numerical calculations are interpreted by a tunable Fano-like resonance and
may lead to interesting applications for blocking and filtering atom beams.
\\ ( http://arXiv.org/abs/nlin/0609032 , 213kb)
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Paper: cond-mat/0604137
replaced with revised version Wed, 13 Sep 2006 03:15:16 GMT (28kb)

Title: Fermion Cooper Pairing with Unequal Masses: Standard Field Theory
Approach
Authors: Lianyi He, Meng Jin and Pengfei Zhuang
Comments: 13 pages, 2 figures, published version, erratum will appear soon
Subj-class: Superconductivity; Atomic Physics
Journal-ref: Phys. Rev. B 74, 024516 (2006)
DOI: 10.1103/PhysRevB.74.024516
\\ ( http://arXiv.org/abs/cond-mat/0604137 , 28kb)
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Paper: cond-mat/0604673
replaced with revised version Wed, 13 Sep 2006 14:54:38 GMT (283kb)

Title: Evolution from a Bose-Einstein Condensate to a Tonks-Girardeau Gas: An
Exact Diagonalization Study
Authors: Frank Deuretzbacher, Kai Bongs, Klaus Sengstock, Daniela Pfannkuche
Subj-class: Other
\\ ( http://arXiv.org/abs/cond-mat/0604673 , 283kb)
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Paper: cond-mat/0606281
replaced with revised version Wed, 13 Sep 2006 00:35:41 GMT (867kb)

Title: A Primary Noise Thermometer for Ultracold Bose Gases
Authors: R. Gati, J. Esteve, B. Hemmerling, T. B. Ottenstein, J. Appmeier, A.
Weller, M. K. Oberthaler
Subj-class: Other
DOI: 10.1088/1367-2630/8/9/189
\\ ( http://arXiv.org/abs/cond-mat/0606281 , 867kb)
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Paper: quant-ph/0609101
Date: Wed, 13 Sep 2006 14:55:43 GMT (364kb)

Title: Anyonic Braiding in Optical Lattices
Authors: Chuanwei Zhang, V.W. Scarola, Sumanta Tewari and S. Das Sarma
\\
Quantum computers are predicted to utilize intrinsically quantum mechanical
properties of matter to perform difficult computational tasks exponentially
faster than ordinary computers. Isolating and manipulating the delicate quantum
states of individual quantum bits as well as carrying out the necessary quantum
error correction essential for quantum computation require a daunting amount of
precision. Topological quantum computation proposes to use braiding of
collective excitations implanted in topologically ordered coherent quantum
states of many particles, as opposed to a single particle, to perform quantum
computation. Here we explicitly work out how to manipulate and detect
topological excitations in a specific system, cold atom optical lattices. A key
feature of these topological excitations is their braiding statistics, how they
behave when one excitation is taken around another. An observation of the
non-trivial braiding statistics described in this Letter would directly
establish the existence of anyons, quantum particles which are neither fermions
nor bosons. Demonstrating anyonic braiding statistics is tantamount to
observing a new form of matter, topological matter. Once created, excitations
in quantum topological matter, as opposed to delicate single particle quantum
states, can provide a much more robust way to encode and manipulate quantum
information.
\\ ( http://arXiv.org/abs/quant-ph/0609101 , 441kb)
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Paper: cond-mat/0609337
Date: Thu, 14 Sep 2006 07:09:15 GMT (385kb)

Title: Quantum Entanglement Manifestation of Transition to Nonlinear
Self-trapping for Bose-Einstein Condensates in a Symmetric Double-Well
Authors: Li-Bin Fu and Jie Liu
Subj-class: Mesoscopic Systems and Quantum Hall Effect
\\
We investigate the nonlinear self-trapping phenomenon of the Bose-Einstein
condensates (BEC) in a symmetric double-well, emphasizing on its behind
dynamical phase transition. With increasing the nonlinear parameter depicting
the interaction between the degenerate atoms the BEC turns to be self-trapped
manifesting an asymmetric distribution of the atomic density profile. Essence
of this phenomenon is revealed to be a continuous phase transition and
underlying critical behavior is studied analytically and found to follow a
logarithm scaling-law. We then go beyond the mean field treatment and extend to
discuss the effect of the many-body quantum fluctuation on the transition. It
is found that the transition point is shifted and the scaling-law is broken. In
particular, the quantum phase transition is accompanied by the change of the
entanglement entropy which is found to reach maximum at transition point.
Behind physics is revealed.
\\ ( http://arXiv.org/abs/cond-mat/0609337 , 385kb)
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Paper: cond-mat/0609338
Date: Thu, 14 Sep 2006 07:22:19 GMT (318kb)

Title: Continuous measurements enhanced self-trapping of degenerate ultra-cold
atoms: Nonlinear Quantum Zeno Effect
Authors: WeiDong Li and Jie Liu
Subj-class: Mesoscopic Systems and Quantum Hall Effect; Other
\\
In the present paper we investigate the influence of measurements on the
quantum dynamics of degenerate bose atoms gases in a symmetric double-well. We
show that continuous measurement could induce an asymmetric distribution of the
atoms density profile and broaden the parameter regime for self-trapping. We
term this phenomenon as nonlinear quantum Zeno effect in analog to the
celebrated Zeno effect in a linear quantum system. Under a discontinuous
measurement, the self-trapping due to the atomic interaction in the degenerate
bosons is shown to be destroyed completely. Underlying physics is revealed and
possible experimental realization is discussed.
\\ ( http://arXiv.org/abs/cond-mat/0609338 , 318kb)
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Paper: cond-mat/0609340
Date: Thu, 14 Sep 2006 07:48:59 GMT (114kb)

Title: The stationary solutions of G-P equations in double square well
Authors: Weidong Li
Comments: 7 pages, 4 figures. accepted by Phys. Rev. A. (2006)
Subj-class: Mesoscopic Systems and Quantum Hall Effect
\\
We present new analytical stationary solutions for the Gross-Pitaevskii
equation (GPE) of a Bose-Einstein condensate (BEC) trapped in a double-well
potential. These solutions are compared with those described by Mahmud et al.,
PRA 66, 063607 (2002). In particular, we provide further evidences that
symmetry preserving stationary solutions can be reduced to the eigenstates of
the corresponding linear Schrodinger equation. Moreover, we found that the
symmetry breaking solutions can emerge not only from bifurcations, but also
from isolated points in the chemical potential-nonlinear interaction diagram.
We also found that there are some moving nodes in the symmetry breaking
solutions.
\\ ( http://arXiv.org/abs/cond-mat/0609340 , 114kb)
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Paper: cond-mat/0609346
Date: Thu, 14 Sep 2006 12:42:59 GMT (169kb)

Title: Luther-Emery Phase and Atomic-Density Waves in a Trapped Fermion Gas
Authors: Gao Xianlong, M. Rizzi, Marco Polini, Rosario Fazio, M.P. Tosi, V.L.
Campo Jr., K. Capelle
Comments: 10 pages, 3 figures, 1 Table, submitted to Phys. Rev. on July 25th
2006
Subj-class: Strongly Correlated Electrons; Superconductivity
\\
The Luther-Emery liquid is a state of matter that is predicted to occur in
one-dimensional systems of interacting fermions and is characterized by a
gapless charge spectrum and a gapped spin spectrum. In this Letter we discuss a
realization of the Luther-Emery phase in a trapped cold-atom gas. We study by
means of the density-matrix renormalization-group technique a two-component
atomic Fermi gas with attractive interactions subject to parabolic trapping
inside an optical lattice. We demonstrate how this system exhibits compound
phases characterized by the coexistence of spin pairing and atomic-density
waves. A smooth crossover occurs with increasing magnitude of the atom-atom
attraction to a state in which tightly bound spin-singlet dimers occupy the
center of the trap. The existence of atomic-density waves could be detected in
the elastic contribution to the light-scattering diffraction pattern.
\\ ( http://arXiv.org/abs/cond-mat/0609346 , 169kb)
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Paper (*cross-listing*): nlin.PS/0609031
Date: Tue, 12 Sep 2006 14:43:16 GMT (936kb)

Title: Simple and efficient generation of gap solitons in Bose-Einstein
condensates
Authors: Michal Matuszewski, Wieslaw Krolikowski, Marek Trippenbach, Yuri S.
Kivshar
Subj-class: Pattern Formation and Solitons; Other
Journal-ref: Phys. Rev. A 73, 063621 (2006)
DOI: 10.1103/PhysRevA.73.063621
\\
We suggest an efficient method for generating matter-wave gap solitons in a
repulsive Bose-Einstein condensate, when the gap soliton is formed from a
condensate cloud in a harmonic trap after turning on a one-dimensional optical
lattice. We demonstrate numerically that this approach does not require
preparing the initial atomic wave packet in a specific state corresponding to
the edge of the Brillouin zone of the spectrum, and losses that occur during
the soliton generation process can be suppressed by an appropriate adiabatic
switching of the optical lattice.
\\ ( http://arXiv.org/abs/nlin/0609031 , 936kb)
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Paper: cond-mat/0507399
replaced with revised version Wed, 13 Sep 2006 20:40:42 GMT (24kb)

Title: The unitary three-body problem in a trap
Authors: F\'{e}lix Werner (LKB - Lhomond), Yvan Castin (LKB - Lhomond)
Comments: 4 pages, version including a prediction for the lifetime of an
Efimovian state
Proxy: ccsd ccsd-00007574
Subj-class: Other
\\ ( http://arXiv.org/abs/cond-mat/0507399 , 24kb)
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Paper: cond-mat/0606677
replaced with revised version Thu, 14 Sep 2006 11:12:25 GMT (636kb)

Title: Response of Bose gases in time-dependent optical superlattices
Authors: M. Hild, F. Schmitt, R. Roth
Subj-class: Statistical Mechanics
\\ ( http://arXiv.org/abs/cond-mat/0606677 , 636kb)
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Paper: cond-mat/0607251
replaced with revised version Thu, 14 Sep 2006 15:20:22 GMT (49kb)

Title: Quantum Phase Transitions of Hard-Core Bosons in Background Potentials
Authors: Anand Priyadarshee, Shailesh Chandrasekharan, Ji-Woo Lee, and Harold
U. Baranger
clarifications
Subj-class: Statistical Mechanics; Superconductivity
Journal-ref: Phys. Rev. Lett. 97, 115703 (2006)
DOI: 10.1103/PhysRevLett.97.115703
\\ ( http://arXiv.org/abs/cond-mat/0607251 , 49kb)
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Paper: cond-mat/0608542
replaced with revised version Thu, 14 Sep 2006 12:58:01 GMT (169kb)

Title: Three-boson recombination at ultralow temperatures
Authors: M.T. Yamashita, T. Frederico and Lauro Tomio
Subj-class: Soft Condensed Matter
\\ ( http://arXiv.org/abs/cond-mat/0608542 , 169kb)
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Paper: cond-mat/0609230
replaced with revised version Thu, 14 Sep 2006 04:50:40 GMT (210kb)

Title: Finite-temperature effects on the number fluctuation of ultracold atoms
across the Superfluid to Mott-insulator transition
Authors: Xiancong Lu and Yue Yu
Comments: 7 pages,7 figures, minor changes
Subj-class: Other
\\ ( http://arXiv.org/abs/cond-mat/0609230 , 210kb)
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Paper: quant-ph/0609103
Date: Thu, 14 Sep 2006 00:38:22 GMT (132kb)

Title: Opacity of electromagnetically induced transparency for quantum
fluctuations
Authors: P. Barberis-Blostein and M. Bienert
\\
We analyze the propagation of a pair of quantized fields inside a medium of
three-level atoms in $\Lambda$ configuration. We calculate the stationary
quadrature noise spectrum of the field after propagating through the medium, in
the case where the probe field is in a squeezed state and the atoms show
electromagnetically induced transparency (EIT). We find an oscillatory transfer
of the initial quantum properties between the probe and pump fields which is
most strongly pronounced when both fields have comparable Rabi frequencies.
This implies that the quantum state measured after propagation can be
completely different from the initial state, even though the mean values of the
field are unaltered.
\\ ( http://arXiv.org/abs/quant-ph/0609103 , 132kb)
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Paper: quant-ph/0603129
replaced with revised version Thu, 14 Sep 2006 01:34:17 GMT (25kb)

Title: Adiabatic Mach-Zehnder Interferometry on A Quantized Bose-Josephson
Junction
Authors: Chaohong Lee
Comments: Revised version, 4 pages, 4 figures, Accepted for publication in
Physical Review Letters
\\ ( http://arXiv.org/abs/quant-ph/0603129 , 25kb)
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Paper: physics/0609120
Date: Thu, 14 Sep 2006 10:39:29 GMT (34kb)

Title: Time invariance violation is a physical base of atomic Bloch
oscillations in an optical lattice
Authors: V.A.Kuz'menko
Subj-class: General Physics; Optics
\\
The physical mechanism of phenomenon is explained as a result of inequality
of forward and reversed processes in optics. The importance of experimental
study of its invariance relation is discussed.
\\ ( http://arXiv.org/abs/physics/0609120 , 34kb)
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Paper: physics/0609116
Date: Thu, 14 Sep 2006 10:28:13 GMT (66kb)

Title: On the Dynamics of the $h-$index in Complex Networks with Coexisting
Communities
Authors: Luciano da Fontoura Costa
Comments: 9 pages, 1 table, 2 figures. A working manuscript: comments and
criticisms are welcomed
Subj-class: Physics and Society
\\
This article investigates the evolution of the $h-$index in a complex network
including two communities (in the sense of having different features) with the
same number of authors whose yearly productions follow the Zipf's law. Models
considering indiscriminate citations, as well as citations preferential to the
fitness values of each community and/or the number of existing citations are
proposed and numerically simulated. The $h-$indices of each type of author is
estimated along a period of 20 years, while the number of authors remains
constant. Interesting results are obtained including the fact that, for the
model where citations are preferential to both community fitness and number of
existing citations per article, the $h-$indices of the community with the
largest fitness value are only moderately increased while the indices of the
other community are severely and irreversibly limited to low values. Three
possible strategies are discussed in order to change this situation. In
addition, based on such findings, a new version of the $h-$index is proposed
involving the automated identification of virtual citations which can provide
complementary and unbiased quantification of the relevance of scientific works.
\\ ( http://arXiv.org/abs/physics/0609116 , 66kb)
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Paper: cond-mat/0609373
Date: Fri, 15 Sep 2006 10:53:57 GMT (151kb)

Title: Pair Excitations and Vertex Corrections in Fermi Fluids
Authors: Helga M. B\"ohm, Eckhard Krotscheck, and Martin Panholzer
Comments: to be published in: JLTP (2007) Proc. Int. Symp. QFS2006, 1-6 Aug.
2006, Kyoto, Japan
Subj-class: Other
\\
Based on an equations--of--motion approach for time--dependent pair
correlations in strongly interacting Fermi liquids, we have developed a theory
for describing the excitation spectrum of these systems. Compared to the known
correlated'' random--phase approximation (CRPA), our approach has the
following properties: i) The CRPA is reproduced when pair fluctuations are
neglected. ii) The first two energy--weighted sumrules are fulfilled implying a
correct static structure. iii) No ad--hoc assumptions for the effective mass
are needed to reproduce the experimental dispersion of the roton in 3He. iv)
The density response function displays a novel form, arising from vertex
corrections in the proper polarisation. Our theory is presented here with
special emphasis on this latter point. We have also extended the approach to
the single particle self-energy and included pair fluctuations in the same way.
The theory provides a diagrammatic superset of the familiar GW approximation.
It aims at a consistent calculation of single particle excitations with an
accuracy that has previously only been achieved for impurities in Bose liquids.
\\ ( http://arXiv.org/abs/cond-mat/0609373 , 151kb)
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\\
Paper: cond-mat/0609374
Date: Fri, 15 Sep 2006 11:15:22 GMT (443kb)

Title: Bose-Einstein Condensation Temperature of Dipolar Gas in Anisotropic
Harmonic Trap
Authors: Konstantin Glaum, Axel Pelster
http://www.theo-phys.uni-essen.de/tp/ags/pelster_dir
Subj-class: Statistical Mechanics
\\
We consider a dilute gas of dipole moments in an arbitrary harmonic trap and
treat both the short-range, isotropic delta-interaction and the long-range,
anisotropic dipole-dipole interaction perturbatively. With this we calculate
the leading shift of the critical temperature with respect to that of an ideal
gas as a function of the relative orientation of the dipole moments with
respect to the harmonic trap axes. In particular, we determine those magic
angles, where the dipolar shift of the Bose-Einstein condensation temperature
vanishes. Furthermore, we show for the parameters of the ongoing
52Cr-experiment in Stuttgart that this dipolar shift can be enhanced by
increasing the number of particles, the geometrical mean trap frequency, and
the anisotropy of the trap.
\\ ( http://arXiv.org/abs/cond-mat/0609374 , 443kb)
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Paper: cond-mat/0609390
Date: Fri, 15 Sep 2006 19:41:56 GMT (78kb)

Title: Precision Measurements of Collective Oscillations in the BEC-BCS
crossover
Authors: A. Altmeyer, S. Riedl, C. Kohstall, M. Wright, R. Geursen, M.
Bartenstein, C. Chin, J. Hecker Denschlag, R. Grimm
Subj-class: Other; Superconductivity
\\
We report on precision measurements of the frequency of the radial
compression mode in a strongly interacting, optically trapped Fermi gas of Li-6
atoms. Our results allow for a test of theoretical predictions for the equation
of state in the BEC-BCS crossover. We confirm recent quantum Monte-Carlo
results and rule out simple mean-field BCS theory. Our results show the
long-sought beyond-mean-field effects in the strongly interacting BEC regime.
\\ ( http://arXiv.org/abs/cond-mat/0609390 , 78kb)
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Paper: cond-mat/0510315
replaced with revised version Fri, 15 Sep 2006 07:21:48 GMT (14kb)

Title: Superfluidity in a gas of strongly-interacting bosons
Authors: G. M. Kavoulakis, Y. Yu, M. Ogren and S. M. Reimann (LTH, Lund)
Comments: 7 pages, 3 figures, revised version, to appear in Europh. Lett
Subj-class: Other
\\ ( http://arXiv.org/abs/cond-mat/0510315 , 14kb)
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Paper: cond-mat/0602080
replaced with revised version Fri, 15 Sep 2006 17:35:58 GMT (51kb)

Title: Squeezing in the weakly interacting uniform Bose condensate
Authors: Masudul Haque (Utrecht), Andrei E. Ruckenstein (Rutgers)
Comments: 8 pages, 3 figures. Version 2 (Sept'06): expanded discussions
Subj-class: Statistical Mechanics; Other
\\ ( http://arXiv.org/abs/cond-mat/0602080 , 51kb)
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Paper: quant-ph/0609111
Date: Thu, 14 Sep 2006 23:53:40 GMT (444kb)

Title: Quantum logic via the exchange blockade in ultracold collisions
Authors: David Hayes, Paul Julienne, Ivan Deutsch
\\
A nuclear spin can act as a quantum switch that turns on or off ultracold
collisions between atoms even when there is neither interaction between nuclear
spins nor between the nuclear and electron spins. This "exchange blockade" is a
new mechanism for implementing quantum logic gates that arises from the
symmetry of composite identical particles, rather than direct coupling between
qubits. We study the implementation of the entangling $\sqrt{\text{SWAP}}$ gate
based on this mechanism for a model system of two atoms with ground electron
configuration $^1S_0$, spin 1/2 nuclei, trapped in optical tweezers. We
evaluate a proof-of-principle protocol based on adiabatic evolution of a one
dimensional double Gaussian well, calculating fidelities of operation as a
function of interaction strength, gate time, and temperature.
\\ ( http://arXiv.org/abs/quant-ph/0609111 , 444kb)
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Paper: physics/0609133
Date: Fri, 15 Sep 2006 11:26:18 GMT (956kb)

Title: Laser cooling and trapping of atomic strontium for ultracold atom
physics, high-precision spectroscopy and quantum sensors
Authors: F. Sorrentino, G. Ferrari, N. Poli, R. Drullinger, and G. M. Tino
Subj-class: Atomic Physics
\\
This review describes the production of atomic strontium samples at ultra-low
temperature and at high phase-space density, and their possible use for
magneto-optical trap from an atomic beam and preparing the sample for high
precision measurements. Particular emphasis is given to the applications of
ultracold Sr samples, spanning from optical frequency metrology to force
sensing at micrometer scale.,
\\ ( http://arXiv.org/abs/physics/0609133 , 956kb)
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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/
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Received on Tue Sep 19 2006 - 15:17:34 EST

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