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The abstracts for this week:
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Paper: cond-mat/0605648
Date: Fri, 26 May 2006 10:53:47 GMT (32kb)
Title: Motion of a vortex line near the boundary of a semi-infinite uniform
condensate
Authors: Peter Mason, Natalia G. Berloff and Alexander L. Fetter
Comments: submitted to Phys Rev A
Subj-class: Soft Condensed Matter
\\
We consider the motion of a vortex in an asymptotically homogeneous
condensate bounded by a solid wall where the wave function of the condensate
vanishes. For a vortex parallel to the wall, the motion is essentially
equivalent to that generated by an image vortex, but the depleted surface layer
induces an effective shift in the position of the image compared to the case of
a vortex pair in an otherwise uniform flow. Specifically, the velocity of the
vortex can be approximated by $U \approx (\hbar/2m)(y_0-\sqrt 2 \xi)^{-1}$,
where $y_0$ is the distance from the center of the vortex to the wall, $\xi$ is
the healing length of the condensate and $m$ is the mass of the boson.
\\ ( http://arXiv.org/abs/cond-mat/0605648 , 32kb)
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Paper: cond-mat/0605663
Date: Fri, 26 May 2006 19:11:05 GMT (120kb)
Title: Critical Casimir force in $^4$He films: confirmation of finite-size
scaling
Authors: A. Ganshin, S. Scheidemantel, R. Garcia and M. H. W. Chan
Comments: 4 pages, 3 figures, submitted to PRL
Subj-class: Soft Condensed Matter
\\
We present new capacitance measurements of critical Casimir force-induced
thinning of $^4$He films near the superfluid/normal transition, focused on the
region below $T_{\lambda}$ where the effect is the greatest. $^4$He films of
238, 285, and 340 \AA thickness are adsorbed on N-doped silicon substrates with
roughness $\approx 8 {\AA}$. The Casimir force scaling function $\vartheta $,
deduced from the thinning of these three films, collapses onto a single
universal curve, attaining a minimum $\vartheta = -1.30 \pm 0.03$ at
$x=td^{1/\nu}=-9.7\pm 0.8 {\AA}^{1/\nu}$. The collapse confirms the finite-size
scaling origin of the dip in the film thickness. Separately, we also confirm
the presence down to $2.13 K$ of the Goldstone/surface fluctuation force, which
makes the superfluid film $\sim 2 {\AA}$ thinner than the normal film.
\\ ( http://arXiv.org/abs/cond-mat/0605663 , 120kb)
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Paper: cond-mat/0603162
replaced with revised version Fri, 26 May 2006 05:55:17 GMT (152kb)
Title: Bose-Fermi mixtures in an optical lattice
Authors: K. Sengupta, N. Dupuis, and P. Majumdar
Comments: v2, minor change
Subj-class: Strongly Correlated Electrons
\\ ( http://arXiv.org/abs/cond-mat/0603162 , 152kb)
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Paper: cond-mat/0603643
replaced with revised version Fri, 26 May 2006 05:56:00 GMT (61kb)
Title: The 1D interacting anyon gas: low-energy properties and Haldane
exclusion statistics
Authors: M.T. Batchelor, X.-W. Guan and N. Oelkers
Comments: 4 pages, 2 figures, minor corrections, to appear in Phys. Rev. Lett
Subj-class: Statistical Mechanics
\\ ( http://arXiv.org/abs/cond-mat/0603643 , 61kb)
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Paper: physics/0605231
Date: Fri, 26 May 2006 05:55:59 GMT (24kb)
Title: Competition between Electromagnetically Induced Transparency and Raman
Processes
Authors: G. S. Agarwal, T. N. Dey, and Daniel J. Gauthier
Comments: 3.5 pages, 7 figures
Subj-class: Optics
\\
We present a theoretical formulation of competition among electromagnetically
induced transparency (EIT) and Raman processes. The latter become important
when the medium can no longer be considered to be dilute. Unlike the standard
formulation of EIT, we consider all fields applied and generated as interacting
with both the transitions of the $\Lambda$ scheme. We solve Maxwell equations
for the net generated field using a fast-Fourier-transform technique and obtain
predictions for the probe, control and Raman fields. We show how the intensity
of the probe field is depleted at higher atomic number densities due to the
build up of multiple Raman fields.
\\ ( http://arXiv.org/abs/physics/0605231 , 24kb)
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Paper: cond-mat/0605684
Date: Sun, 28 May 2006 10:36:44 GMT (278kb)
Title: Finite temperature effects in trapped Fermi gases with population
imbalance
Authors: Chih-Chun Chien, Qijin Chen, Yan He, and K. Levin
Comments: "No comments!"
Subj-class: Strongly Correlated Electrons; Superconductivity
\\
We study the finite temperature $T$ behavior of trapped Fermi gases as they
undergo BCS-Bose Einstein condensation (BEC) crossover, in the presence of a
population imbalance. Our results, in qualitative agreement with recent
experiments, show how the superfluid phase transition is directly reflected in
the particle density profiles. We demonstrate that at $ T \neq 0$ and in the
near-BEC and unitary regimes, the polarization is excluded from the superfluid
core. Nevertheless a substantial polarization fraction is carried by a normal
region of the trap having strong pair correlations, which we associate with
noncondensed pairs or the ``pseudogap phase''.
\\ ( http://arXiv.org/abs/cond-mat/0605684 , 278kb)
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Paper: cond-mat/0605691
Date: Mon, 29 May 2006 06:59:10 GMT (125kb)
Title: Magnetic disorder and dynamical properties of a Bose-Einstein condensate
in atomic waveguides
Authors: Daw-Wei Wang
Comments: 15 pages and 9 figures. An extended work of Phys. Rev. Lett. 92,
076802 (2004)
Subj-class: Other; Disordered Systems and Neural Networks
\\
We systematically investigate the properties of the quenched disorder
potential in an atomic waveguide, and study its effects to the dynamics of
condensate in the strong disorder region. We show that even very small wire
shape fluctuations can cause strong disorder potential along the wire
direction, leading to the fragmentation phenomena as the condensate is close to
the wire surface. The generic disorder potential is Gaussian correlated random
potential with vanishing correlations in both short and long wavelength limits
and with a strong correlation weight at a finite length scale, set by the
atom-wire distance. When the condensate is fragmentized, we investigate the
coherent and incoherent dynamics of the condensate, and demonstrate that it can
undergo a crossover from a coherent condensate to an insulating Bose-glass
phase in strong disorder (or low density) regime. Our numerical results
obtained within the meanfield approximation are semi-quantitatively consistent
with the experimental results.
\\ ( http://arXiv.org/abs/cond-mat/0605691 , 125kb)
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Paper: cond-mat/0605695
Date: Mon, 29 May 2006 08:33:49 GMT (123kb)
Title: Quantum ratchet with cold atoms in a pair of pulsed optical lattices
Authors: Gabriel G. Carlo, Giuliano Benenti, Giulio Casati, Sandro Wimberger,
Oliver Morsch, Riccardo Mannella, Ennio Arimondo
Comments: 6 pages, 7 figures
Subj-class: Other
\\
We present a very simple model for a readily implementable ratchet system. It
consists of two series of spatially periodic kicks. By means of two parameters
all the symmetries that could prevent us from finding directed transport are
removed. A complete characterization of the behavior of the system is given and
its robustness is checked. We conclude that our model offers a clear-cut way to
implement directed transport in an atom optical experiment.
\\ ( http://arXiv.org/abs/cond-mat/0605695 , 123kb)
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Paper: cond-mat/0605699
Date: Mon, 29 May 2006 09:37:19 GMT (301kb)
Title: Theory of vortex-lattice melting in a one-dimensional optical lattice
Authors: Michiel Snoek and H.T.C. Stoof
Comments: 17 pages, 17 figures, submitted to Phys. Rev. A
Subj-class: Other
\\
We investigate quantum and temperature fluctuations of a vortex lattice in a
one-dimensional optical lattice. We discuss in particular the Bloch bands of
the Tkachenko modes and calculate the correlation function of the vortex
positions along the direction of the optical lattice. Because of the small
number of particles in the pancake Bose-Einstein condensates at every site of
the optical lattice, finite-size effects become very important. Moreover, the
fluctuations in the vortex positions are inhomogeneous due to the inhomogeneous
density. As a result, the melting of the lattice occurs from the outside
inwards. However, tunneling between neighboring pancakes substantially reduces
the inhomogeneity as well as the size of the fluctuations. On the other hand,
nonzero temperatures increase the size of the fluctuations dramatically. We
calculate the crossover temperature from quantum melting to classical melting.
We also investigate melting in the presence of a quartic radial potential,
where a liquid can form in the center instead of at the outer edge of the
pancake Bose-Einstein condensates.
\\ ( http://arXiv.org/abs/cond-mat/0605699 , 301kb)
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Paper: cond-mat/0605708
Date: Mon, 29 May 2006 15:49:43 GMT (953kb)
Title: Expansion dynamics of a dipolar Bose-Einstein condensate
Authors: S. Giovanazzi, P. Pedri, L. Santos, A. Griesmaier, M. Fattori, T.
Koch, J. Stuhler, T. Pfau
Comments: 12 pages. Submitted to PRA
Subj-class: Other
\\
Our recent measurements on the expansion of a chromium dipolar condensate
after release from an optical trapping potential are in good agreement with an
exact solution of the hydrodynamic equations for dipolar Bose gases. We report
here the theoretical method used to interpret the measurement data as well as
more details of the experiment and its analysis. The theory reported here is a
tool for the investigation of different dynamical situations in time-dependent
harmonic traps.
\\ ( http://arXiv.org/abs/cond-mat/0605708 , 953kb)
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Paper: cond-mat/0605711
Date: Mon, 29 May 2006 18:39:37 GMT (61kb)
Title: Fragmentation of Bose-Einstein Condensates
Authors: Erich J. Mueller (Cornell), Tin-Lun Ho (OSU), Masahito Ueda (Tokyo
Institute of Technology) and Gordon Baym (UIUC)
Comments: 16 pages, 1 figure, revtex4
Subj-class: Mesoscopic Systems and Quantum Hall Effect
\\
We present the theory of bosonic systems with multiple condensates, unifying
disparate models which are found in the literature, and discuss how
degeneracies, interactions, and symmetries conspire to give rise to this
unusual behavior. We show that as degeneracies multiply, so do the types of
fragmentation, eventually leading to strongly correlated states with no trace
of condensation.
\\ ( http://arXiv.org/abs/cond-mat/0605711 , 61kb)
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Paper: cond-mat/0510301
replaced with revised version Sun, 28 May 2006 10:17:21 GMT (478kb)
Title: Phase Separation of a Fast Rotating Boson-Fermion Mixture in the
Lowest-Landau-Level Regime
Authors: Rina Kanamoto, Makoto Tsubota
Subj-class: Mesoscopic Systems and Quantum Hall Effect; Other
Journal-ref: Phys. Rev. Lett. 96, 200405 (2006)
\\ ( http://arXiv.org/abs/cond-mat/0510301 , 478kb)
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Paper: cond-mat/0601289
replaced with revised version Sat, 27 May 2006 09:06:24 GMT (7kb)
Title: Force on a moving point impurity due to quantum fluctuations in a
Bose-Einstein condensate
Authors: D. C. Roberts
Comments: v2: corrected notation and other minor changes
Subj-class: Statistical Mechanics; Other
\\ ( http://arXiv.org/abs/cond-mat/0601289 , 7kb)
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Paper: cond-mat/0602346
replaced with revised version Mon, 29 May 2006 17:26:12 GMT (610kb)
Title: Population and Phase Coherence during the Growth of an Elongated
Bose-Einstein Condensate
Authors: Mathilde Hugbart (LCFIO), Jocelyn A. Retter (LCFIO), Andres Var\`{o}n
(LCFIO), Philippe Bouyer (LCFIO), Alain Aspect (LCFIO), Matthew J. Davis (ARC
QUANTUM OPTICS)
Proxy: ccsd ccsd-00018350
Subj-class: Other
\\ ( http://arXiv.org/abs/cond-mat/0602346 , 610kb)
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Paper: cond-mat/0603498
replaced with revised version Mon, 29 May 2006 05:51:42 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)
\\ ( http://arXiv.org/abs/cond-mat/0603498 , 682kb)
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Paper: quant-ph/0605231
Date: Sat, 27 May 2006 13:34:01 GMT (135kb)
Title: A single cold atom as efficient stationary source of EPR-entangled light
Authors: David Vitali, Giovanna Morigi, J\"urgen Eschner
Comments: 13 pages, 5 figures
\\
The Stokes and anti-Stokes components of the spectrum of resonance
fluorescence of a single trapped atom, which originate from the mechanical
coupling between the scattered photons and the quantized motion of the atomic
center of mass, exhibit quantum correlations which are of two-mode-squeezing
type. We study and demonstrate the build-up of such correlations in a specific
setup, which is experimentally accessible, and where the atom acts as efficient
and continuous source of EPR-entangled, two-mode squeezed light.
\\ ( http://arXiv.org/abs/quant-ph/0605231 , 135kb)
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Paper: quant-ph/0605234
Date: Mon, 29 May 2006 07:00:43 GMT (209kb)
Title: Integration of fiber coupled high-Q silicon nitride microdisks with
magnetostatic atom chips
Authors: Paul E. Barclay, Kartik Srinivasan, Oskar Painter, Benjamin Lev, Hideo
Mabuchi
\\
Micron scale silicon nitride (SiNx) microdisk optical resonators fabricated
on a silicon wafer are demonstrated with Q = 3.6 x 10^6 (finesse = 5 x 10^4)
and an effective mode volume of 15 (\lambda / n)^3 at wavelengths \lambda ~ 852
nm resonant with the D2 transition manifold of cesium. A dilute hydrofluoric
wet etch is shown to provide sensitive tuning of the microdisk optical
resonances, and robust mounting of a fiber taper provides efficient fiber optic
coupling to the SiNx microdisk cavities while allowing unfettered optical
access for laser cooling and trapping of atoms. Initial measurement of a hybrid
atom-cavity chip indicates that cesium adsorption on the surface of the SiNx
microdisks results in significant red-detuning of the disk resonances. A
technique for parallel integration of multiple (10) microdisks with a single
optical fiber taper is also demonstrated.
\\ ( http://arXiv.org/abs/quant-ph/0605234 , 313kb)
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Paper: quant-ph/0605237
Date: Mon, 29 May 2006 08:25:32 GMT (157kb)
Title: Estimation of fluctuating magnetic fields by an atomic magnetometer
Authors: Vivi Petersen and Klaus Molmer
Comments: 8 pages, 6 figures
\\
We present a theoretical analysis of the ability of atomic magnetometers to
estimate a fluctuating magnetic field. Our analysis makes use of a Gaussian
state description of the atoms and the probing field, and it presents the
estimator of the field and a measure of its uncertainty which coincides in the
appropriate limit with the achievements for a static field. We show by
simulations that the estimator for the current value of the field
systematically lags behind the actual value of the field, and we suggest a more
complete theory, where measurement results at any time are used to update and
improve both the estimate of the current value and the estimate of past values
of the B-field.
\\ ( http://arXiv.org/abs/quant-ph/0605237 , 157kb)
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Paper: quant-ph/0605238
Date: Mon, 29 May 2006 09:25:53 GMT (2kb)
Title: Erratum : Squeezing and entanglement delay using slow light
Authors: G. Hetet, A. Peng, M. T. Johnsson, M. T. L. Hsu, O. Gloeckl, P. K.
Lam, H .A. Bachor, and J. J. Hope
Comments: 1 page, no figure
\\
An inconsistency was found in the equations used to calculate the variance of
the quadrature fluctuations of a field propagating through a medium
demonstrating electromagnetically induced transparency (EIT). The decoherence
term used in our original paper introduces inconsistency under weak probe
approximation. In this erratum we give the Bloch equations with the correct
dephasing terms. The conclusions of the original paper remain the same. Both
entanglement and squeezing can be delayed and preserved using EIT without
adding noise when the decoherence rate is small.
\\ ( http://arXiv.org/abs/quant-ph/0605238 , 2kb)
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Paper: quant-ph/0605244
Date: Mon, 29 May 2006 16:27:04 GMT (11kb)
Title: Stochastic One-Way Quantum Computing with Ultracold Atoms in Optical
Lattices
Authors: Michael C. Garrett and David L. Feder
Comments: 4 pages, 2 figures, REVTeX, Qcircuit.tex included
\\
The cluster state, the highly entangled multipartite initial state required
for one-way quantum computing, can be generated from a gas of ultracold atoms
confined in a 2D optical lattice. In practice, a systematic phase error is
expected, resulting in imperfect cluster states. We present a solution to this
problem, wherein the teleportation protocol is necessarily stochastic if the
value of the phase error is not known.
\\ ( http://arXiv.org/abs/quant-ph/0605244 , 11kb)
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Paper: quant-ph/0605245
Date: Mon, 29 May 2006 17:46:19 GMT (66kb)
Title: Manipulating Single Neutral Atoms in Optical Lattices
Authors: Chuanwei Zhang, S. L. Rolston, and S. Das Sarma
Comments: 5 pages, 3 figures
\\
We analyze a scheme to manipulate quantum states of neutral atoms at
individual sites of optical lattices using focused laser beams. Spatial
distributions of focused laser intensities induce position-dependent energy
shifts of hyperfine states, which, combined with microwave radiation, allow
selective manipulation of quantum states of individual target atoms. We show
that various errors in the manipulation process are suppressed below $% 10^{-4}
$ with properly chosen microwave pulse sequences and laser parameters. A
similar idea is also applied to measure quantum states of single atoms in
optical lattices.
\\ ( http://arXiv.org/abs/quant-ph/0605245 , 66kb)
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Paper: cond-mat/0605736
Date: Tue, 30 May 2006 15:02:45 GMT (152kb)
Title: Long Distance Transport of Ultracold Atoms using a 1D optical lattice
Authors: Stefan Schmid, Gregor Thalhammer, Klaus Winkler, Florian Lang, and
Johannes Hecker Denschlag
Comments: 15 pages, 8 figures
Subj-class: Other
\\
We study the horizontal transport of ultracold atoms over macroscopic
distances of up to 20 cm with a moving 1D optical lattice. By using an optical
Bessel beam to form the optical lattice, we can achieve almost homogeneous
trapping conditions over the full transport length, which is necessary to hold
the atoms against gravity for such a wide range. Fast transport velocities of
up to 6 m/s (corresponding to about 1100 photon recoils) and accelerations of
up to 2600 m/s^2 are reached. Even at high velocities the momentum of the atoms
is precisely defined with an uncertainty of less than one photon recoil. This
allows for construction of an atom catapult with high kinetic energy
resolution, which might have applications in novel collision experiments.
\\ ( http://arXiv.org/abs/cond-mat/0605736 , 152kb)
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Paper: cond-mat/0605743
Date: Tue, 30 May 2006 18:30:58 GMT (21kb)
Title: Cyclic Lattice Feshbach Resonances
Authors: Fei Zhou (PITP, Ubc)
Comments: 4 pages, 2 figures included
Subj-class: Other
\\
In this Letter we illustrate the possible cyclic fermion pairing states
across Feshbach resonances in optical lattices. In cyclic fermion pairing, the
pairing amplitude exhibits an oscillatory behavior as the detuning varies. We
estimate the quasi-particle gaps in different regimes of the resonances.
\\ ( http://arXiv.org/abs/cond-mat/0605743 , 21kb)
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Paper: cond-mat/0605744
Date: Tue, 30 May 2006 18:51:49 GMT (60kb)
Title: Finite temperature phase diagram of a polarised Fermi condensate
Authors: M. M. Parish, F. M. Marchetti, A. Lamacraft and B. D. Simons
Comments: 5 pages, 4 figures
Subj-class: Other
\\
The two-component Fermi gas is the simplest fermion system displaying
superfluidity, and as such finds applications ranging from the theory of
superconductivity to QCD. Ultracold atomic gases provide an exceptionally clean
realization of this system, where the interatomic interaction and the atom
species population are both independent, tuneable parameters. This allows one
to investigate the Fermi gas with imbalanced spin populations, which had
previously been experimentally elusive, and this prospect has stimulated much
theoretical activity. Here we show that the finite temperature phase diagram
contains a region of phase separation between the superfluid and normal states
that touches the boundary of second-order superfluid transitions at a
tricritical point, reminiscent of the phase diagram of $^3$He-$^4$He mixtures.
A variation of interaction strength then results in a line of tricritical
points that terminates at zero temperature on the molecular Bose-Einstein
condensate (BEC) side. On this basis, we argue that tricritical points will
play an important role in the recent experiments on polarised atomic Fermi
gases.
\\ ( http://arXiv.org/abs/cond-mat/0605744 , 60kb)
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Paper (*cross-listing*): nucl-th/0605071
Date: Fri, 26 May 2006 13:59:25 GMT (13kb)
Date (revised v2): Mon, 29 May 2006 10:33:24 GMT (13kb)
Title: Cold asymmetrical fermion superfluids in nonperturbative renormalisation
group
Authors: Boris Krippa
Comments: 11 pages, 2 figures, revtex
Subj-class: Nuclear Theory; Superconductivity
\\
The application of the nonperturbative renormalisation group approach to a
system with two fermion species is studied. Assuming a simple ansatz for the
effective action with effective bosons, describing pairing effects we derive a
set of approximate flow equations for the effective coupling including boson
and fermionic fluctuations. The case of two fermions with different masses but
coinciding Fermi surfaces is considered.
The phase transition to a phase with broken symmetry is found at a critical
value of the running scale. The large mass difference is found to disfavour the
formation of pairs.
The mean-field results are recovered if the effects of boson loops are
omitted. While the boson fluctuation effects were found to be negligible for
large values of $p_{F} a$ they become increasingly important with decreasing
$p_{F} a$ thus making the mean field description less accurate.
\\ ( http://arXiv.org/abs/nucl-th/0605071 , 13kb)
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Paper: cond-mat/0601650
replaced with revised version Tue, 30 May 2006 19:30:14 GMT (31kb)
Title: Dynamics of the Bose-Hubbard model: transition from Mott insulator to
superfluid
Authors: Fernando M. Cucchietti, Bogdan Damski, Jacek Dziarmaga, and Wojciech
H. Zurek
Comments: 6+ pages, the significantly extended version of the former submission
Report-no: LAUR-06-0477
Subj-class: Other
\\ ( http://arXiv.org/abs/cond-mat/0601650 , 31kb)
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Paper: cond-mat/0604095
replaced with revised version Tue, 30 May 2006 10:37:04 GMT (151kb)
Title: Tuning the Mott transition in a Bose-Einstein condensate by multi-photon
absorption
Authors: C.E. Creffield and T.S. Monteiro
Comments: Minor changes, this version to be published in Phys. Rev. Lett
Subj-class: Other
\\ ( http://arXiv.org/abs/cond-mat/0604095 , 151kb)
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Paper (*cross-listing*): math-ph/0412056
replaced with revised version Tue, 30 May 2006 14:16:19 GMT (8kb)
Title: Equivalence of Bose-Einstein condensation and symmetry breaking
Authors: Andras Suto
Comments: An error in my summary of previous results (the definition of F') is
corrected. The correction is to be done also in the PRL
Subj-class: Mathematical Physics; Statistical Mechanics
Journal-ref: Phys.Rev.Lett. 94 (2005) 080402
DOI: 10.1103/PhysRevLett.94.080402
\\ ( http://arXiv.org/abs/math-ph/0412056 , 8kb)
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Paper (*cross-listing*): quant-ph/0601083
replaced with revised version Tue, 30 May 2006 08:18:09 GMT (179kb)
Title: Simulating high-temperature superconductivity model Hamiltonians with
atoms in optical lattices
Authors: Alexander Klein and Dieter Jaksch
Comments: 9 pages, 4 figures; title, abstract and introduction changed, more
examples included; accepted for publication in Phys. Rev. A
Subj-class: Quantum Physics; Other
Journal-ref: Phys. Rev. A 73, 053613 (2006)
DOI: 10.1103/PhysRevA.73.053613
\\ ( http://arXiv.org/abs/quant-ph/0601083 , 179kb)
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Paper: cond-mat/0605751
Date: Wed, 31 May 2006 18:16:45 GMT (236kb)
Title: Universal phase diagram of a strongly interacting Fermi gas with
unbalanced spin populations
Authors: Fr\'{e}d\'{e}ric Chevy (LKB - Lhomond)
Comments: 4 pages, 2 figures
Proxy: ccsd ccsd-00077712
Subj-class: Statistical Mechanics
\\
We present a theoretical interpretation of a recent experiment presented in
ref. \cite{Zwierlein06} on the density profile of Fermi gases with unbalanced
spin populations. We show that in the regime of strong interaction, the
boundaries of the three phases observed in \cite{Zwierlein06} can be
characterized by two dimensionless numbers $\eta\_\alpha$ and $\eta\_\beta$.
Using a combination of a variational treatment and a study of the experimental
results, we infer rather precise bounds for these two parameters.
\\ ( http://arXiv.org/abs/cond-mat/0605751 , 236kb)
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Paper: cond-mat/0605754
Date: Wed, 31 May 2006 16:51:13 GMT (21kb)
Title: Spin polarizability of a trapped superfluid Fermi gas
Authors: A. Recati, I. Carusotto, C. Lobo and S. Stringari
Subj-class: Soft Condensed Matter; Other
\\
The polarization produced by the relative displacement of the potentials
trapping two spin species of a dilute Fermi gas with $N_\ua=N_\da$ is
calculated at unitarity by assuming phase separation between the superfluid and
a spin polarized phase at zero temperature. Due to the energy cost associated
with pair breaking, the dipole magnetic polarizability vanishes in the linear
limit and exhibits important deviations from the ideal gas behaviour even for
displacements of the order of the size of the atomic cloud. The magnetic
behaviour in the presence of different trapping frequencies for the two spin
species is also discussed.
\\ ( http://arXiv.org/abs/cond-mat/0605754 , 21kb)
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Paper: cond-mat/0605755
Date: Wed, 31 May 2006 18:25:46 GMT (63kb)
Title: Disorder-Induced Shift of Condensation Temperature for Dilute Trapped
Bose Gases
Authors: Matthias Timmer, Axel Pelster, and Robert Graham
Comments: Author information under
http://www.theo-phys.uni-essen.de/tp/ags/pelster_dir
Subj-class: Disordered Systems and Neural Networks
\\
We determine the leading shift of the Bose-Einstein condensation temperature
for an ultracold dilute atomic gas in a harmonic trap due to weak disorder by
treating both a Gaussian and a Lorentzian spatial correlation for the quenched
disorder potential. Increasing the correlation length from values much smaller
than the geometric mean of the trap scale and the mean particle distance to
much larger values leads first to an increase of the positive shift to a
maximum at this critical length scale and then to a decrease.
\\ ( http://arXiv.org/abs/cond-mat/0605755 , 63kb)
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Paper: quant-ph/0605252
Date: Wed, 31 May 2006 19:07:32 GMT (814kb)
Title: Photoassociation adiabatic passage of ultracold Rb atoms to form
ultracold Rb_2 molecules
Authors: Evgeny A. Shapiro, Moshe Shapiro, Avi Pe'er, and Jun Ye
Comments: RevTex, 23 pages, 9 figures
\\
We theoretically explore photoassociation by Adiabatic Passage of two
colliding cold ^{85}Rb atoms in an atomic trap to form an ultracold Rb_2
molecule in its ground ro-vibrational level. We consider the incoherent thermal
nature of the scattering process in a trap and show that coherent manipulations
of the atomic ensemble, such as adiabatic passage, are feasible if performed
within the coherence time window dictated by the temperature, which is
relatively long for cold atoms. By repeating the coherent process many times
efficient association of the thermal cloud can be achieved. We show that a
sequence of ~2*10^7 pulses of moderate intensities, each lasting ~750 ns, can
efficiently photoassociate an entire atomic ensemble at temperature of 100 \muK
and density of 10^{11} atoms/cm^3. Use of multiple pathways and multiple pulse
sequences makes it easier to populate the target vibrational state.
\\ ( http://arXiv.org/abs/quant-ph/0605252 , 814kb)
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Paper: cond-mat/0506809
replaced with revised version Wed, 31 May 2006 17:55:38 GMT (109kb)
Title: d-wave resonating valence bond states of fermionic atoms in optical
lattices
Authors: Simon Trebst, Ulrich Schollwoeck, Matthias Troyer, Peter Zoller
Comments: 4+ pages, 5 figures
Subj-class: Strongly Correlated Electrons; Superconductivity
\\ ( http://arXiv.org/abs/cond-mat/0506809 , 109kb)
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Paper: cond-mat/0606015
Date: Thu, 1 Jun 2006 16:52:34 GMT (360kb)
Title: Experimental study of the transport of coherent interacting matter-waves
in a 1D random potential induced by laser speckle
Authors: David Cl\'{e}ment (LCFIO), Andr\`{e}s F. Var\`{o}n (LCFIO), Jocelyn A.
Retter (LCFIO), Laurent Sanchez-Palencia (LCFIO), Alain Aspect (LCFIO),
Philippe Bouyer (LCFIO)
Proxy: ccsd ccsd-00077779
Subj-class: Other
\\
We present a detailed analysis of the 1D expansion of a coherent interacting
matterwave (a Bose-Einstein condensate) in the presence of disorder. A 1D
random potential is created via laser speckle patterns. It is carefully
calibrated and the self-averaging properties of our experimental system are
discussed. We observe the suppression of the transport of the BEC in the random
potential. We discuss the scenario of disorder-induced trapping taking into
account the radial extension in our experimental 3D BEC and we compare our
experimental results with the theoretical predictions.
\\ ( http://arXiv.org/abs/cond-mat/0606015 , 360kb)
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Paper: cond-mat/0606029
Date: Thu, 1 Jun 2006 10:15:49 GMT (23kb)
Title: Effect of Dynamics on Finite Systems in Thermal Equilibrium
Authors: Shyamal Biswas
Comments: 4 pages, 2 figures
Subj-class: Statistical Mechanics
\\
We show quantitatively the role of the dynamics of the constituent particles
of a finite sized system in equilibrium with a heat bath. In thermodynamical
systems the dynamics of its constituent particles play no role in determining
the probability of its state under the condition of equilibrium. But the
dynamics is important at very low temperature when thermal de Broglie wave
length of its constituent particles become comparable to the system size. In
that case we show that specific heat of the system can be negative. There is a
discontinuity of specific heat at a constant temperature below which there is
no effect of thermal interaction on the system. We quantitatively discuss the
thermodynamic limit in particular for the case of Bose Einstein condensation.
\\ ( http://arXiv.org/abs/cond-mat/0606029 , 23kb)
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Paper (*cross-listing*): hep-th/0605259
Date: Thu, 25 May 2006 22:51:59 GMT (23kb)
Title: Symmetry Aspects in Nonrelativistic Multi-Scalar Field Models and
Application to a Coupled Two-Species Dilute Bose Gas
Authors: Rudnei O Ramos and Marcus B Pinto
Comments: 8 pages, 1 eps figure, IOP style. Based on a talk given by R. O.
Ramos at the QFEXT05 workshop, Barcelona, Spain, September 5-9, 2005
Subj-class: High Energy Physics - Theory; Soft Condensed Matter
Journal-ref: J.Phys. A39 (2006) 6687-6693
\\
We discuss unusual aspects of symmetry that can happen due to entropic
effects in the context of multi-scalar field theories at finite temperature. We
present their consequences, in special, for the case of nonrelativistic models
of hard core spheres. We show that for nonrelativistic models phenomena like
inverse symmetry breaking and symmetry non-restoration cannot take place, but a
reentrant phase at high temperatures is shown to be possible for some region of
parameters. We then develop a model of interest in studies of Bose-Einstein
condensation in dilute atomic gases and discuss about its phase transition
patterns. In this application to a Bose-Einstein condensation model, however,
no reentrant phases are found.
\\ ( http://arXiv.org/abs/hep-th/0605259 , 23kb)
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Paper: cond-mat/0601681
replaced with revised version Wed, 31 May 2006 20:40:21 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.
Scalettar
Comments: 13 pages, 23 figures
Subj-class: Other; Strongly Correlated Electrons
Journal-ref: Physical Review B 73, 174516 (2006)
DOI: 10.1103/PhysRevB.73.174516
\\ ( http://arXiv.org/abs/cond-mat/0601681 , 226kb)
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Paper: cond-mat/0602048
replaced with revised version Thu, 1 Jun 2006 13:51:20 GMT (188kb)
Title: Coherent transport of cold atoms in angle-tuned optical lattices
Authors: Roberto Franzosi, Matteo Cristiani, Carlo Sias, Ennio Arimondo
Comments: 8 pages, 5 figures, one section added, in press in Phys. Rev. A
Subj-class: Other
\\ ( http://arXiv.org/abs/cond-mat/0602048 , 188kb)
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Paper: cond-mat/0603113
replaced with revised version Wed, 31 May 2006 23:27:28 GMT (27kb)
Title: Stability analysis for $n$-component Bose-Einstein condensate
Authors: David C. Roberts and Masahito Ueda
Comments: v2: added reference
Subj-class: Other; Statistical Mechanics
Journal-ref: Phys. Rev. A 73, 053611 (2006)
\\ ( http://arXiv.org/abs/cond-mat/0603113 , 27kb)
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Paper: quant-ph/0606003
Date: Wed, 31 May 2006 21:13:06 GMT (21kb)
Title: Indirect decoherence in optical lattices and cold gases
Authors: Daniel Braun
Comments: 12 pages, 1 figure
\\
The interaction of two--level atoms with a common heat bath leads to an
effective interaction between the atoms, such that with time the internal
degrees of the atoms become correlated or even entangled. If part of the atoms
remain unobserved this creates additional indirect decoherence for the selected
atoms, on top of the direct decoherence due to the interaction with the heat
bath. I show that indirect decoherence can drastically increase and even
dominate the decoherence for sufficiently large times. I investigate indirect
decoherence through thermal black body radiation quantitatively for atoms
trapped at regular positions in an optical lattice as well as for atoms at
random positions in a cold gas, and show how indirect coherence can be
controlled or even suppressed through experimentally accessible parameters.
\\ ( http://arXiv.org/abs/quant-ph/0606003 , 21kb)
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Paper: quant-ph/0606013
Date: Thu, 1 Jun 2006 15:11:31 GMT (306kb)
Title: Collective coherent population trapping in a thermal field
Authors: M. Macovei, Z. Ficek, C. H. Keitel
Comments: Accepted for publication in Phys. Rev. A
\\
We analyzed the efficiency of coherent population trapping (CPT) in a
superposition of the ground states of three-level atoms under the influence of
the decoherence process induced by a broadband thermal field. We showed that in
a single atom there is no perfect CPT when the atomic transitions are affected
by the thermal field. The perfect CPT may occur when only one of the two atomic
transitions is affected by the thermal field. In the case when both atomic
transitions are affected by the thermal field, we demonstrated that regardless
of the intensity of the thermal field the destructive effect on the CPT can be
circumvented by the collective behavior of the atoms. An analytic expression
was obtained for the populations of the upper atomic levels which can be
considered as a measure of the level of thermal decoherence. The results show
that the collective interaction between the atoms can significantly enhance the
population trapping in that the population of the upper state decreases with
increased number of atoms. The physical origin of this feature was explained by
the semiclassical dressed atom model of the system. We introduced the concept
of multiatom collective coherent population trapping by demonstrating the
existence of collective (entangled) states whose storage capacity is larger
than that of the equivalent states of independent atoms.
\\ ( http://arXiv.org/abs/quant-ph/0606013 , 306kb)
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Paper: quant-ph/0606018
Date: Thu, 1 Jun 2006 18:34:43 GMT (366kb)
Title: Transfer of trapped atoms between two optical tweezer potentials
Authors: Matthias Schulz, Herbert Crepaz, Ferdinand Schmidt-Kaler, Juergen
Eschner, Rainer Blatt
\\
Trapped, laser-cooled rubidium atoms are transferred between two strongly
focused, horizontal, orthogonally intersecting laser beams. The transfer
efficiency is studied as a function of the vertical distance between the beam
axes. Optimum transfer is found when the distance equals the beam waist radius.
Numerical simulations reproduce well the experimental results.
\\ ( http://arXiv.org/abs/quant-ph/0606018 , 366kb)
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Till next time,
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/ ========================================================================= Legal stuff: Unless stated otherwise, this e-mail represents only the views of the sender and not the views of the University of Queensland =========================================================================Received on Mon Jun 05 2006 - 09:13:54 EST
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