# Matt's arXiv selection, Friday 18th August 2006.

From: Matthew Davis <mdavis_at_physics.uq.edu.au>
Date: Sat, 19 Aug 2006 00:52:32 +1000 (EST)

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

Hi all,

Things should be back to normal from next week - hopefully I will manage to
board a plane from London Heathrow on Sunday back to Brisbane.

The abstracts:

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Paper: cond-mat/0608291
Date: Sun, 13 Aug 2006 21:41:56 GMT (280kb)

Title: Collective oscillations of dipolar Bose-Einstein condensates and
accurate comparison between contact and dipolar interaction
Authors: S. Giovanazzi, L. Santos, T. Pfau
Subj-class: Other
\\
We propose a scheme for the measurement of the s-wave scattering length $a$
of an atom or molecule with significant dipole-dipole interaction with an
accuracy at the percent level. The frequencies of the collective oscillations
of a Bose-Einstein condensate are shifted by the magnetic dipole interaction.
The shift is polarization dependent and proportional to the ratio
$\epsilon_{dd}$ of dipolar and s-wave coupling constants. Measuring the
differences in the frequencies for different polarization we can extract the
value of $\epsilon_{dd}$ and thus measure $a$. We calculate the frequency
shifts for a large variety of non-axisymmetric harmonic traps in the
Thomas-Fermi limit and find optimal trapping geometries to maximize the shifts.
\\ ( http://arXiv.org/abs/cond-mat/0608291 , 280kb)
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Paper: cond-mat/0608306
Date: Mon, 14 Aug 2006 08:58:56 GMT (90kb)

Title: Quantum polarization spectroscopy of ultracold spinor gases
Authors: K. Eckert, L. Zawitkowski, A. Sanpera, M. Lewenstein, E.S. Polzik
Subj-class: Other
\\
We propose a method for the detection of ground state quantum phases of
spinor gases through a series of two quantum nondemolition measurements
performed by sending off-resonant, polarized light pulses through the gas.
Signatures of various mean-field as well as strongly-correlated phases of F=1
and F=2 spinor gases obtained by detecting quantum fluctuations and mean values
of polarization of transmitted light are identified.
\\ ( http://arXiv.org/abs/cond-mat/0608306 , 90kb)
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Paper: cond-mat/0608316
Date: Mon, 14 Aug 2006 19:35:49 GMT (898kb)

Title: Vortex in a trapped Bose-Einstein condensate with dipole-dipole
interactions
Authors: Duncan H. J. O'Dell, Claudia Eberlein
Subj-class: Other
\\
We calculate the critical rotation frequency at which a vortex state becomes
energetically favorable over the vortex-free ground state in a harmonically
trapped Bose-Einstein condensate whose atoms have dipole-dipole interactions as
well as the usual s-wave contact interactions. In the Thomas-Fermi
(hydrodynamic) regime, dipolar condensates in oblate cylindrical traps (with
the dipoles aligned along the axis of symmetry of the trap) tend to have lower
critical rotation frequencies than their purely s-wave contact interaction
counterparts. The converse is true for dipolar condensates in prolate traps.
Quadrupole excitations and centre of mass motion are also briefly discussed as
possible competing mechanisms to a vortex as means by which superfluids with
partially attractive interactions might carry angular momentum
\\ ( http://arXiv.org/abs/cond-mat/0608316 , 898kb)
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Paper: cond-mat/0606330
replaced with revised version Mon, 14 Aug 2006 15:10:48 GMT (623kb)

Title: Sarma Phase in Trapped Unbalanced Fermi Gases
Authors: K. B. Gubbels, M. W. J. Romans, and H. T. C. Stoof
Subj-class: Statistical Mechanics
\\ ( http://arXiv.org/abs/cond-mat/0606330 , 623kb)
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Paper: cond-mat/0608154
replaced with revised version Sat, 12 Aug 2006 20:19:45 GMT (16kb)

Title: Pairing and Superfluid Properties of Dilute Fermion Gases at Unitarity
Authors: Vamsi K. Akkineni, D.M. Ceperley, Nandini Trivedi
Comments: 4 pages, 4 figures, To be submitted to PRL Minor errors corrected
Subj-class: Statistical Mechanics; Superconductivity
\\ ( http://arXiv.org/abs/cond-mat/0608154 , 16kb)
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Paper: quant-ph/0608109
Date: Sun, 13 Aug 2006 07:22:55 GMT (68kb)

Title: Controlled splitting of an atomic wave packet
Authors: M. Zhang, P. Zhang, M. S. Chapman and L. you
Comments: 4 pages, 4 figures. Accepted by Phys. Rev. Lett
\\
We propose a simple scheme capable of adiabatically splitting an atomic wave
packet using two independent translating traps. Implemented with optical dipole
traps, our scheme allows a high degree of flexibility for atom interferometry
arrangements and highlights its potential as an efficient and high fidelity
atom optical beam splitter.
\\ ( http://arXiv.org/abs/quant-ph/0608109 , 68kb)
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Paper: cond-mat/0608321
Date: Tue, 15 Aug 2006 07:20:45 GMT (109kb)

Title: Unitary Fermi gas at finite temperature in the epsilon expansion
Authors: Yusuke Nishida
Comments: 12 pages, 6 figures, revtex4
Report-no: INT-PUB 06-13, TKYNT-06-11
Subj-class: Other
\\
Thermodynamics of the unitary Fermi gas at finite temperature is investigated
from the perspective of the expansion over epsilon=4-d with d being the
dimensionality of space. We show that the thermodynamics is dominated by
bosonic excitations in the low temperature region where T<<Tc. Analytic
formulas for the thermodynamic functions as functions of the temperature are
derived to the lowest order in epsilon in this region. In the high temperature
region where T~Tc, bosonic and fermionic quasiparticles are excited and we
determine the critical temperature Tc and the thermodynamic functions around Tc
\\ ( http://arXiv.org/abs/cond-mat/0608321 , 109kb)
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Paper: cond-mat/0608335
Date: Tue, 15 Aug 2006 16:58:47 GMT (148kb)

Title: Superfluid -- Mott insulator transition of ultracold gases in optical
resonators
Authors: Jonas Larson, Bogdan Damski, Giovanna Morigi, Maciej Lewenstein
Report-no: LAUR-06-5423
Subj-class: Other
\\
The physics of a ultracold atomic gas in the potential formed inside a pumped
optical resonator is critically affected by the photon-mediated interaction
between the atoms. The presence of the atoms determines the cavity resonance,
and thus the intracavity field amplitude, which then determines atomic
localization and the quantum phase of the gas. We study the superfluid -- Mott
insulator quantum phase transition in this system in one dimension. The
coefficients of the effective Bose-Hubbard model depend non-linearly on the
number of atoms, and have to be evaluated self-consistently. We predict the
existence of overlapping, competing Mott phases and bistable behavior in the
vicinity of the shifted cavity resonance, controlled by the pump parameters.
\\ ( http://arXiv.org/abs/cond-mat/0608335 , 148kb)
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Paper: cond-mat/0601604
replaced with revised version Tue, 15 Aug 2006 08:15:15 GMT (291kb)

Title: Thermal fluctuations of vortex clusters in quasi-two-dimensional
Bose-Einstein condensate
Authors: W. V. Pogosov and K. Machida
Comments: 8 pages, 3 figures; final version, accepted for publication in Phys.
Rev. A
Subj-class: Statistical Mechanics; Other
\\ ( http://arXiv.org/abs/cond-mat/0601604 , 291kb)
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Paper: cond-mat/0602119
replaced with revised version Tue, 15 Aug 2006 08:06:32 GMT (31kb)

Title: Effect of thermal fluctuations on spin degrees of freedom in spinor
Bose-Einstein condensates
Authors: W. V. Pogosov, K. Machida
Comments: 5 pages, 2 figures; final version, accepted for publication in Phys.
Rev. A
Subj-class: Other
\\ ( http://arXiv.org/abs/cond-mat/0602119 , 31kb)
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Paper: cond-mat/0602667
replaced with revised version Tue, 15 Aug 2006 08:46:43 GMT (239kb)

Title: Twisted vortex state
Authors: V.B. Eltsov, A.P. Finne, R. Hanninen, J. Kopu, M. Krusius, M. Tsubota,
E.V. Thuneberg
Comments: 5 pages, 4 figures, RevTeX file, corrected after the referee comments
Subj-class: Soft Condensed Matter
Journal-ref: Phys. Rev. Lett. 96, 215302 (2006)
DOI: 10.1103/PhysRevLett.96.215302
\\ ( http://arXiv.org/abs/cond-mat/0602667 , 239kb)
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Paper: cond-mat/0604505
replaced with revised version Tue, 15 Aug 2006 07:58:03 GMT (82kb)

Title: Cyclic phase in F=2 spinor condensate: Long-range order, kinks, and
roughening transition
Authors: W. V. Pogosov, K. Machida
Comments: 6 pages, 1 figure; final version, accepted for publication in Phys.
Rev. A
Subj-class: Statistical Mechanics
\\ ( http://arXiv.org/abs/cond-mat/0604505 , 82kb)
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Paper: cond-mat/0608135
replaced with revised version Tue, 15 Aug 2006 06:33:47 GMT (382kb)

Title: Disruption of reflecting Bose-Einstein condensates due to quantum noise
and modulational instability
Authors: R.G. Scott, D.A.W. Hutchinson and C.W. Gardiner
Subj-class: Other
\\ ( http://arXiv.org/abs/cond-mat/0608135 , 382kb)
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Paper: cond-mat/0608350
Date: Wed, 16 Aug 2006 08:41:46 GMT (114kb)

Title: Mean-field theory for Bose-Hubbard Model under a magnetic field
Authors: M.O. Oktel, M. Nita, B. Tanatar
Subj-class: Statistical Mechanics
\\
We consider the superfluid-insulator transition for cold bosons under an
effective magnetic field. We investigate how the applied magnetic field affects
the Mott transition within mean field theory and find that the critical hopping
strength $(t/U)_c$, increases with the applied field. The increase in the
critical hopping follows the bandwidth of the Hofstadter butterfly at the given
value of the magnetic field. We also calculate the magnetization and superfluid
density within mean field theory.
\\ ( http://arXiv.org/abs/cond-mat/0608350 , 114kb)
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Paper: cond-mat/0608351
Date: Wed, 16 Aug 2006 09:46:15 GMT (69kb)

Title: Exact numerical simulations of a one-dimensional, trapped Bose gas
Authors: Bernd Schmidt, Michael Fleischhauer
Subj-class: Other
\\
We analyze the ground-state and low-temperature properties of a
one-dimensional Bose gas in a harmonic trapping potential using the numerical
density matrix renormalization group. Calculations cover the whole range from
the Bogoliubov limit of weak interactions to the Tonks-Girardeau limit. Local
quantities such as density and local three-body correlations are calculated and
shown to agree very well with analytic predictions within a local density
approximation. The transition between temperature dominated to quantum
dominated correlation is determined and it is shown that despite the presence
of the harmonic trapping potential first-order correlations display over a
large range the algebraic decay of a harmonic fluid with a Luttinger parameter
determined by the density at the trap center.
\\ ( http://arXiv.org/abs/cond-mat/0608351 , 69kb)
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Paper: cond-mat/0608355
Date: Wed, 16 Aug 2006 17:40:16 GMT (638kb)

Title: A Quantum Top Inside a Bose Josephson Junction
Authors: Ingrid Bausmerth, Uwe R. Fischer, Anna Posazhennikova
Comments: 4 pages of RevTex4, 4 figures
Subj-class: Other
\\
We consider an atomic quantum dot confined between two weakly-coupled
Bose-Einstein condensates, where the dot serves as an additional tunneling
channel. It is shown that the thus-embedded atomic quantum dot is a pseudospin
subject to an external torque, and therefore equivalent to a quantum top. We
demonstrate by numerical analysis of the time-dependent coupled evolution
equations that this microscopic quantum top is very sensitive to any deviation
from linear oscillatory behavior of the condensates. In certain special cases,
the dot can even induce or modify the tunneling between the macroscopic
condensates in the two wells.
\\ ( http://arXiv.org/abs/cond-mat/0608355 , 638kb)
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Paper: cond-mat/0604184
replaced with revised version Wed, 16 Aug 2006 03:14:22 GMT (29kb)

Title: Two-species fermion mixtures with population imbalance
Authors: M. Iskin and C. A. R. Sa de Melo
Comments: 4 pages with 3 figures, accepted version to PRL
Subj-class: Superconductivity; Other
\\ ( http://arXiv.org/abs/cond-mat/0604184 , 29kb)
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Paper: cond-mat/0608365
Date: Thu, 17 Aug 2006 19:53:31 GMT (91kb)

Title: Sagnac interference in Carbon nanotube loops
Authors: Gil Refael, Jinseong Heo, Marc Bockrath
Subj-class: Mesoscopic Systems and Quantum Hall Effect; Strongly Correlated
Electrons
\\
In this paper we study electron interference in nanotube loops. The
conductance as a function of the applied voltage is shown to oscillate due to
interference between electron beams traversing the loop in two opposite
directions, with slightly different velocities. The period of these
oscillations with respect to the gate voltage, as well as the temperatures
required for the effect to appear, are shown to be much larger than those of
the related Fabry-Perot interference. This effect is analogous to the Sagnac
effect in light interferometers. We calculate the effect of interactions on the
period of the oscillations, and show that even though interactions destroy much
of the near-degeneracy of velocities in the symmetric spin channel, the slow
interference effects survive.
\\ ( http://arXiv.org/abs/cond-mat/0608365 , 91kb)
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Paper: cond-mat/0608370
Date: Wed, 16 Aug 2006 22:26:01 GMT (193kb)

Title: Atom trapping with a thin magnetic film
Authors: Micah Boyd, Erik W. Streed, Patrick Medley, Gretchen K. Campbell,
Jongchul Mun, Wolfgang Ketterle, David E. Pritchard
Subj-class: Other
\\
We have created a $^{87}$Rb Bose-Einstein condensate in a magnetic trapping
potential produced by a hard disk platter written with a periodic pattern. Cold
atoms were loaded from an optical dipole trap and then cooled to BEC on the
surface with radiofrequency evaporation. Fragmentation of the atomic cloud due
to imperfections in the magnetic structure was observed at distances closer
than 40 $\mu$m from the surface. Attempts to use the disk as an atom mirror
showed dispersive effects after reflection.
\\ ( http://arXiv.org/abs/cond-mat/0608370 , 193kb)
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Paper: cond-mat/0603772
replaced with revised version Wed, 16 Aug 2006 21:06:05 GMT (136kb)

Title: A Bose-Einstein condensate interferometer with macroscopic arm
separation
Authors: O. Garcia, B. Deissler, K. J. Hughes, J. M. Reeves and C.A. Sackett
Subj-class: Other
\\ ( http://arXiv.org/abs/cond-mat/0603772 , 136kb)
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Paper: cond-mat/0604638
replaced with revised version Thu, 17 Aug 2006 16:17:29 GMT (363kb)

Title: Surface Tension in Unitary Fermi Gases with Population Imbalance
Authors: Theja N. De Silva, Erich J. Mueller
Comments: 4 pages, 4 figures, Published version
Subj-class: Other
Journal-ref: Phys. Rev. Lett. 97, 070402 (2006)
DOI: 10.1103/PhysRevLett.97.070402
\\ ( http://arXiv.org/abs/cond-mat/0604638 , 363kb)
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Paper: quant-ph/0608133
Date: Thu, 17 Aug 2006 13:44:49 GMT (90kb)

Title: High fidelity teleportation between light and atoms
Authors: K. Hammerer, E.S. Polzik, J.I. Cirac
Comments: 5 pages, 3 figures, submitted to PRA
\\
We show how high fidelity quantum teleportation of light to atoms can be
achieved in the same setup as was used in the recent experiment [J. Sherson
et.al., quant-ph/0605095, accepted by Nature], where such an inter-species
quantum state transfer was demonstrated for the first time. Our improved
protocol takes advantage of the rich multimode entangled structure of the state
of atoms and scattered light and requires simple post-processing of homodyne
detection signals and squeezed light in order to achieve fidelities up to 90%
(85%) for teleportation of coherent (qubit) states under realistic experimental
conditions. The remaining limitation is due to atomic decoherence and light
losses.
\\ ( http://arXiv.org/abs/quant-ph/0608133 , 90kb)
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Paper: physics/0608183
Date: Thu, 17 Aug 2006 17:30:12 GMT (137kb)

Title: Superiority of the $h$-index over the Impact Factor for Physics
Authors: Casey W. Miller
Comments: 4 pages, 3 figures; Submitted to Am. J. Phys. (cordially rejected by
Nat. Phys.)
Subj-class: Physics and Society
\\
Focusing specifically on physics periodicals, I show that the journal Impact
Factor is not correlated with Hirsch's $h$-index. This implies that the Impact
Factor is not a good measure of research quality or influence because the
$h$-index is a reflection of peer review, and thus a strong indicator of
research quality. The impact gap between multidisciplinary journals and
physics-only journals is significantly reduced when $h$ is used instead of the
Impact Factor. Additionally, the impact of journals specializing in review
articles is inherently deflated using $h$ because of the limited number of
annual publications in such periodicals. Finally, a reordering of the top
ranking journals occurs with $h$ when only the physics articles of
multidisciplinary journals are considered, falling more in line with the
average physicist's interpretation of a journal's prestige.
\\ ( http://arXiv.org/abs/physics/0608183 , 137kb)
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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 Sat Aug 19 2006 - 00:52:32 EST

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