[Matts-arxiv] Matt's arXiv selection: week ending 28 May 2010

From: Matthew Davis <mdavis_at_physics.uq.edu.au>
Date: Fri, 18 Jun 2010 17:16:57 +1000

Dear subscribers,

This week's selection was compiled by Chris Foster, and contains 34 new
abstracts and 13 replacements.

arXiv:1005.3846 (*cross-listing*)
Date: Thu, 20 May 2010 21:31:52 GMT (489kb)

Title: Cold heteronuclear atom-ion collisions
Authors: Christoph Zipkes, Stefan Palzer, Lothar Ratschbacher, Carlo Sias,
   Michael K\"ohl
Categories: physics.atom-ph quant-ph
   We study cold heteronuclear atom ion collisions by immersing a trapped single
ion into an ultracold atomic cloud. Using ultracold atoms as reaction targets,
our measurement is sensitive to elastic collisions with extremely small energy
transfer. The observed energy-dependent elastic atom-ion scattering rate
deviates significantly from the prediction of Langevin but is in full agreement
with the quantum mechanical cross section. Additionally, we characterize
inelastic collisions leading to chemical reactions at the single particle level
and measure the energy-dependent reaction rate constants. The reaction products
are identified by in-trap mass spectrometry, revealing the branching ratio
between radiative and non-radiative charge exchange processes.
\\ ( http://arxiv.org/abs/1005.3846 , 489kb)
Date: Fri, 21 May 2010 11:14:23 GMT (84kb)

Title: Josephson effects in one-dimensional supersolids
Authors: M. Kunimi, Y. Nagai and Y. Kato
Categories: cond-mat.quant-gas
Comments: 5 pages, 5 figures
   We demonstrate that superfluidity past an obstacle is possible in a solid
phase in the one-dimensional Gross-Pitaevskii equation with a finite-range
two-body interaction. The phenomenon we find is analogous to the DC Josephson
effect in superconductors and we deduce the " Josephson relation " between the
current and phase difference of the condensates separated by the obstacle. The
phase diagram in the plane of the current and the interaction strength is
\\ ( http://arxiv.org/abs/1005.3936 , 84kb)
Date: Fri, 21 May 2010 14:02:15 GMT (1075kb,D)

Title: A slow gravity compensated Atom Laser
Authors: G. Kleine B\"uning, J. Will, W. Ertmer, C. Klempt, J. Arlt
Categories: cond-mat.quant-gas
Comments: 7 pages, 8 figures, to be published in Applied Physics B
DOI: 10.1007/s00340-010-4078-7
   We report on a slow guided atom laser beam outcoupled from a Bose-Einstein
condensate of 87Rb atoms in a hybrid trap. The acceleration of the atom laser
beam can be controlled by compensating the gravitational acceleration and we
reach residual accelerations as low as 0.0027 g. The outcoupling mechanism
allows for the production of a constant flux of 4.5x106 atoms per second and
due to transverse guiding we obtain an upper limit for the mean beam width of
4.6 \mu\m. The transverse velocity spread is only 0.2 mm/s and thus an upper
limit for the beam quality parameter is M2=2.5. We demonstrate the potential
of the long interrogation times available with this atom laser beam by
measuring the trap frequency in a single measurement. The small beam width
together with the long evolution and interrogation time makes this atom laser
beam a promising tool for continuous interferometric measurements.
\\ ( http://arxiv.org/abs/1005.3964 , 1075kb)
Date: Fri, 21 May 2010 16:19:49 GMT (1421kb)

Title: Antiferromagnetic Order and Bose-Einstein Condensation in
   Strongly-Correlated Cold-Atom Systems: Bosonic t-J Model in the Double-CP1
Authors: Yuki Nakano, Takumi Ishima, Naohiro Kobayashi, Kazuhiko Sakakibara,
   Ikuo Ichinose, Tetsuo Matsui
Categories: cond-mat.quant-gas cond-mat.str-el
Comments: 13 pages, 17 figures
   We study the three-dimensional bosonic t-J model, i.e., the t-J model of
"bosonic electrons" at finite temperatures. This model describes a system of
cold bosonic atoms with two species in an optical lattice. The model is derived
from the Hubbard model for very large on-site repulsive interaction between
bosons of same species (hard-core nature) and also strong correlations between
different species. The operator B_{x\sigma} for an atom at the site x with a
two-component (pseudo-) spin \sigma (=1,2) is treated as a hard-core boson
operator, and represented by a composite of two slave particles; a spinon
described by a CP1 field (Schwinger boson) z_{x\sigma} and a holon described
by a hard-core-boson field \phi_x as B_{x\sigma}=\phi^\dag_x z_{x\sigma}.
\phi_x is then expressed by a pseudo-spin, which is, in turn, represented by
another CP1 (pseudo) spinon w_{x\eta} as \phi_x = w_{x2}^\dag w_{x1}. We then
have a double-CP1 representation of the model by z_{x\sigma} and w_{x\eta}. By
means of Monte Carlo simulations of this bosonic t-J model, we study its phase
structure and the possible phenomena like appearance of antiferromagnetic
long-range order, Bose-Einstein condensation, phase separation, etc. They
should be compared with the possible experimental results of a recently studied
boson-boson mixture like ^87Rb and ^41K in an optical lattice.
\\ ( http://arxiv.org/abs/1005.3997 , 1421kb)
Date: Fri, 21 May 2010 17:40:15 GMT (5403kb)

Title: Black-hole lasers in Bose-Einstein condensates
Authors: Stefano Finazzi and Renaud Parentani
Categories: cond-mat.quant-gas gr-qc
Comments: iopams, 36 pages, 14 figures, 1 table; for associated gif animations,
   see http://people.sissa.it/~finazzi/bec_bhlasers/movies/
   We consider elongated condensates that cross twice the speed of sound. In the
absence of periodic boundary conditions, the phonon spectrum possesses a
discrete and finite set of complex frequency modes which induce a laser effect.
This effect is due, on one hand, to the anomalous dispersion of the phonons
and, on the other hand, to the supersonic region which acts as a resonant
cavity. We numerically compute the complex frequencies and density-density
correlation function. We obtain patterns with very specific signatures. In
terms of the gravitational analogy, the flows we consider correspond to a pair
of black hole and white hole horizons, and the laser effect can be conceived as
a self-amplified Hawking radiation. This is verified by comparing the outgoing
flux at early time with the standard black hole radiation.
\\ ( http://arxiv.org/abs/1005.4024 , 5403kb)
Date: Fri, 21 May 2010 17:45:21 GMT (660kb)

Title: Bose-Einstein supersolid phase for a novel type of momentum dependent
Authors: Xiaopeng Li and W. Vincent Liu and Chungwei Lin
Categories: cond-mat.quant-gas cond-mat.other cond-mat.supr-con
Comments: 4 pages 3 figures
   Motivated by the experiments of dipolar quantum gases, we study a system of
bosons with long range interaction in the regime between superfluid and Wigner
crystal phases. From the effective field theory analysis of low energy
fluctuations and the variational comparison of energies, a novel class of
interaction potentials is found to favor crystalline Bose-Einstein condensation
in the ground state against both the standard homogeneous BEC and
non-superfluid Wigner crystal states. The mechanism is that the potentials
display a minimal value at a finite momentum considerably lower than at zero
\\ ( http://arxiv.org/abs/1005.4027 , 660kb)
Date: Fri, 21 May 2010 20:59:29 GMT (216kb)

Title: Observation of a two-dimensional Fermi gas of atoms
Authors: Kirill Martiyanov, Vasiliy Makhalov, Andrey Turlapov
Categories: cond-mat.quant-gas
   We have prepared a degenerate gas of fermionic atoms which move in two
dimensions while the motion in the third dimension is "frozen" by tight
confinement and low temperature. {\it In situ} imaging provides direct
measurement of the density profile and temperature. The gas is confined in a
defect-free optical potential, and the interactions are widely tunable by means
of a Fano--Feshbach resonance. This system can be a starting point for
exploration of 2D Fermi physics and critical phenomena in a pure, controllable
\\ ( http://arxiv.org/abs/1005.4076 , 216kb)
arXiv:1005.4085 (*cross-listing*)
Date: Fri, 21 May 2010 21:33:20 GMT (193kb,D)

Title: Tunable Cavity Optomechanics with Ultracold Atoms
Authors: T.P. Purdy, D.W.C. Brooks, T. Botter, N. Brahms, Z.-Y. Ma and D.M.
Categories: quant-ph physics.atom-ph physics.optics
Comments: 4 pages, 5 figures
   We present an atom-chip-based realization of quantum cavity optomechanics
with cold atoms localized within a Fabry-Perot cavity. Effective sub-wavelength
positioning of the atomic ensemble allows for tuning the linear and quadratic
optomechanical coupling parameters, varying the sensitivity to the displacement
and strain of a compressible gaseous cantilever. We observe effects of such
tuning on cavity optical nonlinearity and optomechanical frequency shifts,
providing their first characterization in the quadratic-coupling regime.
\\ ( http://arxiv.org/abs/1005.4085 , 193kb)
Date: Sat, 22 May 2010 12:02:33 GMT (308kb)

Title: Spin dynamics and domain formation of a spinor Bose-Einstein condensate
   in an optical cavity
Authors: Lu Zhou, Han Pu, Hong Y. Ling, Keye Zhang and Weiping Zhang
Categories: cond-mat.quant-gas
Comments: 8 pages, 5 figures, submitted to Phys. Rev. A
   We consider a ferromagnetic spin-1 Bose-Einstein condensate (BEC)
dispersively coupled to a unidirectional ring cavity. We show that the ability
of a cavity to modify, in a highly nonlinear fashion, matter-wave phase shifts
adds a new dimension to the study of spinor condensates both within and beyond
the single-mode approximation. In addition to demonstrating strong matter-wave
bistability as in our earlier publication [L. Zhou et al., Phys. Rev. Lett.
103, 160403 (2009)], we show that the interplay between atomic and cavity
fields can greatly enrich both the physics of critical slowing down in spin
mixing dynamics and the physics of spin-domain formation in spinor condensates.
\\ ( http://arxiv.org/abs/1005.4121 , 308kb)
arXiv:1005.4213 (*cross-listing*)
Date: Sun, 23 May 2010 17:25:03 GMT (320kb)

Title: Cold matter trapping via rotating helical optical potential
Authors: A.Yu.Okulov
Categories: physics.atom-ph cond-mat.quant-gas nlin.PS physics.optics
Comments: 6 pages, 3 figures
   We consider a cold bosonic ensemble trapping by a helical interference
pattern in the optical $loop$ scheme. The counter propagating Laguerre-Gaussian
beams with slightly detuned frequencies produce helical potential provided
their optical angular momenta are counter directed. The small frequency
difference required for helix rotation might be induced by Sagnac effect. For
the large number of atoms trapped by a slowly rotating helical optical
potential the Gross-Pitaevskii equation is solved in Thomas-Fermi
approximation. Two possible configurations of the atomic ensemble wavefunction
are presented. The optical $loop$ scheme requirements are briefly formulated.
\\ ( http://arxiv.org/abs/1005.4213 , 320kb)
Date: Mon, 24 May 2010 17:01:33 GMT (109kb,D)

Title: Effect of buffer gas on electromagnetically induced transparency in a
   ladder system using thermal rubidium vapor
Authors: Armen Sargsyan, David Sarkisyan, Ulrich Krohn, James Keaveney, Charles
Categories: physics.atom-ph
Comments: 4 pages, 4 figures
   We report on the first observation of electromagnetically induced
transparency (EIT) in a ladder system in the presence of a buffer gas. In
particular we study the 5S1/2 - 5P3/2 - 5D5/2 transition in thermal rubidium
vapor with a neon buffer gas at a pressure of 6 Torr. In contrast to the line
narrowing effect of buffer gas on {\Lambda}-systems we show that the presence
of the buffer gas leads to an additional broadening of (32 5) MHz, which
suggests a cross section for Rb(5D5/2)-Ne of {\sigma} = (7 1) x 10-19 m2.
However, in the limit where the coupling Rabi frequency is larger than k the
collisional dephasing a strong transparency feature can still be observed.
\\ ( http://arxiv.org/abs/1005.4377 , 109kb)
arXiv:1005.4391 (*cross-listing*)
Date: Mon, 24 May 2010 18:23:06 GMT (501kb)

Title: Cold atoms in rotating optical lattice with nearest neighbour
Authors: Rashi Sachdeva, Sonika Johri and Sankalpa Ghosh
Categories: cond-mat.quant-gas quant-ph
Comments: 9 pages, 3 figures
   Extended Bose Hubbard models with nearest neighbour interaction describe
minimally the effect of long range interaction on ultra cold atoms in deep
optical lattices. Rotation of such optical lattices subject such neutral cold
atoms to the effect of an artificial magnetic field. The modification of the
phase boundaries of the Density wave and Mott Insulator phases due to this
rotation are shown to be related to the edge spectrum of spinorial and scalar
Harper equation. Corresponding profiles of the checkerboard vortex states with
sublattice modulated superfluid order parameter near density wave phase
boundary are calculated.
\\ ( http://arxiv.org/abs/1005.4391 , 501kb)
Date: Tue, 25 May 2010 03:56:07 GMT (581kb)

Title: Ultracold bosons in a synthetic periodic magnetic field: Mott phases and
   re-entrant superfluid-insulator transitions
Authors: K. Saha, K. Sengupta, and K. Ray
Categories: cond-mat.str-el
Comments: 8 pages, 11 figures, v1
   We study Mott phases and superfluid-insulator (SI) transitions of ultracold
bosonic atoms in a two-dimensional square optical lattice at commensurate
filling and in the presence of a synthetic periodic vector potential
characterized by a strength $p$ and a period $l=qa$, where $q$ is an integer
and $a$ is the lattice spacing. We show that the Schr\"odinger equation for the
non-interacting bosons in the presence of such a periodic vector potential can
be reduced to an one-dimensional Harper-like equation which yields $q$ energy
bands. The lowest of these bands have either single or double minima whose
position within the magnetic Brillouin zone can be tuned by varying $p$ for a
given $q$. Using these energies and a strong-coupling expansion technique, we
compute the phase diagram of these bosons in the presence of a deep optical
lattice. We chart out the $p$ and $q$ dependence of the momentum distribution
of the bosons in the Mott phases near the SI transitions and demonstrate that
the bosons exhibit several re-entrant field-induced SI transitions for any
fixed period $q$. We also predict that the superfluid density of the resultant
superfluid state near such a SI transition has a periodicity $q$ ($q/2$) in
real space for odd (even) $q$ and suggest experiments to test our theory.
\\ ( http://arxiv.org/abs/1005.4476 , 581kb)
Date: Tue, 25 May 2010 09:37:30 GMT (339kb)

Title: Extracting the Mott gap from energy measurements in trapped atomic gases
Authors: Juan Carrasquilla and Federico Becca
Categories: cond-mat.quant-gas
Comments: 4 pages and 5 figures
   We show that the measure of the so-called {\it release-energy}, which is an
experimentally accessible quantity, makes it possible to assess the value of
the Mott gap in the presence of the confinement potential that is unavoidable
in the actual experimental setup. Indeed, the curve of the release-energy as a
function of the total number of particles shows kinks that are directly related
to the existence of excitation gaps. Calculations are presented within the
Gutzwiller approach, but the final results go beyond this simple approximation
and represent a genuine feature of the real system. In the case of harmonic
confinement, the Mott gaps may be renormalized with respect to the uniform
case. On the other hand, in the case of the recently proposed off-diagonal
confinement, our results show an almost perfect agreement with the homogeneous
\\ ( http://arxiv.org/abs/1005.4519 , 339kb)
Date: Wed, 26 May 2010 03:06:34 GMT (249kb)

Title: Anderson localization of a Tonks-Girardeau gas in potentials with
   controlled disorder
Authors: J. Radi\'c, V. Ba\v{c}i\'c, D. Juki\'c, M. Segev, H. Buljan
Categories: cond-mat.quant-gas
   We theoretically demonstrate features of Anderson localization in the
Tonks-Girardeau gas confined in one-dimensional (1D) potentials with controlled
disorder. That is, we investigate the evolution of the single particle density
and correlations of a Tonks-Girardeau wave packet in such disordered
potentials. The wave packet is initially trapped, the trap is suddenly turned
off, and after some time the system evolves into a localized steady state due
to Anderson localization. The density tails of the steady state decay
exponentially, while the coherence in these tails increases. The latter
phenomenon corresponds to the same effect found in incoherent optical solitons.
\\ ( http://arxiv.org/abs/1005.4726 , 249kb)
Date: Wed, 26 May 2010 06:21:34 GMT (104kb)

Title: Infinite invariant densities for anomalous diffusion in optical lattices
   and other logarithmic potentials
Authors: David A. Kessler and Eli Barkai
Categories: cond-mat.stat-mech math-ph math.MP
Comments: 4 pages, 2 figures
   We solve the Fokker-Planck equation for Brownian motion in a logarithmic
potential. When the diffusion constant is below a critical value the solution
approaches a non-normalizable scaling state, reminiscent of an infinite
invariant density. With this non-normalizable density we obtain the phase
diagram of anomalous diffusion for this important process. We briefly discuss
the consequence for a range of physical systems including atoms in optical
lattices and charges in vicinity of long polyelectrolytes. Our work explains in
what sense the infinite invariant density and not Boltzmann's equilibrium
describes the long time limit of these systems.
\\ ( http://arxiv.org/abs/1005.4737 , 104kb)
Date: Wed, 26 May 2010 06:26:21 GMT (1074kb)

Title: Splitting and oscillation of Majorana zero modes in the p-wave BCS-BEC
   evolution with plural vortices
Authors: T. Mizushima, K. Machida
Categories: cond-mat.quant-gas cond-mat.supr-con
Comments: 15 pages, 10 figures
   We investigate how the vortex-vortex separation changes Majorana zero modes
in the vicinity of the BCS-BEC (Bose-Einstein condensation) topological phase
transition of p-wave resonant Fermi gases. By analytically and numerically
solving the Bogoliubov-de Gennes equation for spinless p-wave superfluids with
plural vortices, it is demonstrated that the quasiparticle tunneling between
neighboring vortices gives rise to the quantum oscillation of the low-lying
spectra on the scale of the Fermi wavelength in addition to the exponential
splitting. This rapid oscillation, which appears in the weak coupling regime as
a consequence of quantum oscillations of quasiparticle wave functions,
disappears in the vicinity of the BCS-BEC topological phase transition. This is
understandable from that the wave function of the Majorana zero modes is
described by the modified Bessel function in the strong coupling regime and
thus it becomes spread over the vortex core region. Due to the exponential
divergence of the modified Bessel function, the concrete realization of the
Majorana zero modes near the topological phase transition requires the
neighboring vortices to be separated beyond the length scale defined by the
coherence length and the dimensionless coupling constant. All these behaviors
are also confirmed by carrying out the full numerical diagonalization of the
non-local Bogoliubov-de Gennes equation in a two dimensional geometry.
Furthermore, this argument is expanded into the case of three-vortex systems,
where a pair of core-bound and edge-bound Majorana states survive at zero
energy state regardless of the vortex separation.
\\ ( http://arxiv.org/abs/1005.4738 , 1074kb)
Date: Wed, 26 May 2010 08:51:50 GMT (249kb)

Title: Texture control in a pseudospin Bose-Einstein condensate
Authors: Gary Ruben, Michael J. Morgan, and David M. Paganin
Categories: cond-mat.quant-gas
Comments: 4 pages, 5 figures, REVTeX4-1
   We describe a wavefunction engineering approach to the formation of textures
in a two-component nonrotated Bose-Einstein condensate. By controlling the
phases of wavepackets that combine in a three-wave interference process, a
ballistically-expanding regular lattice-texture is generated, in which the
phases determine the component textures. A particular example is presented of a
lattice-texture composed of half-quantum vortices and spin-2 textures. We
demonstrate the lattice formation with numerical simulations of a viable
experiment, identifying the textures and relating their locations to a linear
theory of wavepacket interference.
\\ ( http://arxiv.org/abs/1005.4760 , 249kb)
Date: Wed, 26 May 2010 10:45:00 GMT (1982kb,D)

Title: Zero-temperature phase diagram of Bose-Fermi gaseous mixtures in optical
Authors: T. P. Polak and T. K. Kope\'c
Categories: cond-mat.quant-gas
DOI: 10.1103/PhysRevA.81.043612
   We study the ground state phase diagram of a mixture of bosonic and fermionic
cold atoms confined on two- and three-dimensional optical lattices. The
coupling between bosonic fluctuations and fermionic atoms can be attractive or
repulsive and has similarities with electron-phonon coupling in crystals. We
investigate behavior of the mixtures in the limit, where the Bogoliubov sound
velocity that dictates bosonic dynamics is comparable to the Fermi velocity,
hence the retardation effects are important part of the physics. The dynamic
Lindhard response function of the fermionic density to changes in the bosonic
number of particles above some critical frequency can alter the sign and in
consequence the inter-species interaction between particles becomes repulsive
in contrast to the static limit (instantaneous and always attractive).
Considering the above we show that the structure of the phase diagrams
crucially depends on the difference in masses of the bosons and fermions. We
discuss the situations where integrating out fermionic field provides an
additional interaction that can decrease or increase bosonic coherence.
\\ ( http://arxiv.org/abs/1005.4784 , 1982kb)
Date: Wed, 26 May 2010 10:56:10 GMT (879kb,D)

Title: Frustration effects in rapidly rotating square and triangular optical
Authors: T. P. Polak and T. K. Kope\'c
Categories: cond-mat.quant-gas
DOI: 10.1103/PhysRevA.79.063629
   We discuss the ground state of the two-dimensional Bose-Hubbard (BH)
Hamiltonian, relevant for rotating gaseous Bose-Einstein condensates, by
employing \mathrm{U}\left(1\right) quantum rotor approach and the topologically
constrained path integral that includes a summation over
\mathrm{U}\left(1\right) topological charge. We derive an effective quantum
action for the BH model, which enables a non-perturbative treatment of the
zero-temperature phase transition. We calculate the ground-state phase diagram,
analytically deriving maximum repulsive energy for several rational values of
the frustration rotation parameter f=0, 1/2, 1/3, 1/4, and 1/6 for the square
and triangular lattice, which improves upon previous theoretical treatments.
The ground state of the rotating Bose-Einstein condensates on a triangular
lattice appears to be most stable against the effects of rotation. Performed
calculations revealed strong dependence of the critical ratio of the kinetic
energy to the repulsive on-site energy, that separates the global coherent from
the insulating state, on topology of the lattice.
\\ ( http://arxiv.org/abs/1005.4787 , 879kb)
arXiv:1005.4790 (*cross-listing*)
Date: Wed, 26 May 2010 11:18:20 GMT (73kb)

Title: Reduction of quantum noise and increase of amplification of
   gravitational waves signals in Michelson interferometer by the use of
   squeezed states
Authors: Yacob Ben-Aryeh
Categories: gr-qc quant-ph
Comments: 6 pages
Report-no: 7664
   It is shown in the present Letter that the quantum noise due to high laser
intensities in Michelson interferometer for gravitational waves detection can
be reduced by sending squeezed vacuum states to the 'dark' port of the
interferometer. The experimental details of such physical system have been
described in a recent article by Barak and Ben-Aryeh (JOSA-B, 25, 361(2008)).
In another very recent article by Voronov and Weyrauch (Phys. Rev.A 81, 053816
(2010)) they have followed our methods for treating the same physical system,
and have pointed out an error in the sign of one of our expressions thus
claiming for the elimination of our physical results. I show here a method by
which the expectation value for the photon number operator is increased and at
the same time the standard deviation is reduced. Although due to the mistake in
sign in our expression the physical method for obtaining such result is
different from our original study [1], the main physical effect can remain .
\\ ( http://arxiv.org/abs/1005.4790 , 73kb)
Date: Wed, 26 May 2010 13:56:13 GMT (1195kb,D)

Title: Ultracold Atoms in an Optical Lattice with Dynamically Variable
Authors: S. Al-Assam, R. A. Williams, C. J. Foot
Categories: cond-mat.quant-gas
Comments: 4 pages, 3 figures
   The first use of a dynamic `accordion' lattice with ultracold atoms is
demonstrated. Ultracold atoms of $^{87}$Rb are trapped in a two-dimensional
optical lattice, and the spacing of the lattice is then increased in both
directions from 2.2 microns to 5.5 microns. It is shown that the atoms remain
bound for expansion times as short as a few milliseconds, and the
experimentally measured minimum ramp time is found to agree well with numerical
calculations. This technique allows an experiment such as quantum simulations
to be performed with a lattice spacing smaller than the resolution limit of the
imaging system, while allowing imaging of the atoms at individual lattice sites
by subsequent expansion of the optical lattice.
\\ ( http://arxiv.org/abs/1005.4816 , 1195kb)
Date: Wed, 26 May 2010 16:17:36 GMT (581kb)

Title: A master equation approach for interacting slow- and stationary-light
Authors: Martin Kiffner and Michael J. Hartmann
Categories: quant-ph
   A master equation approach for the description of dark-state polaritons in
coherently driven atomic media is presented. This technique provides a
description of light-matter interactions under conditions of
electromagnetically induced transparency (EIT) that is well suited for the
treatment of polariton losses. The master equation approach allows us to
describe general polariton-polariton interactions that may be conservative,
dissipative or a mixture of both. In particular, it enables us to study
dissipation-induced correlations as a means for the creation of strongly
correlated polariton systems. Our technique reveals a loss mechanism for
stationary-light polaritons that has not been discussed so far. We find that
polariton losses in level configurations with non-degenerate ground states can
be a multiple of those in level schemes with degenerate ground states.
\\ ( http://arxiv.org/abs/1005.4865 , 581kb)
Date: Thu, 27 May 2010 11:38:42 GMT (195kb)

Title: Weak chaos in the disordered nonlinear Schroedinger chain: destruction
   of Anderson localization by Arnold diffusion
Authors: D. M. Basko
Categories: cond-mat.dis-nn
Comments: 98 pages
   The subject of this study is the long-time equilibration dynamics of a
strongly disordered one-dimensional chain of coupled weakly anharmonic
classical oscillators. It is argued that chaos in this system has a very
particular spatial structure: it can be viewed as a dilute gas of chaotic
spots. Each chaotic spot corresponds to a stochastic pump which drives the
Arnold diffusion of the oscillators surrounding it, thus leading to their
relaxation and thermalization. The most important mechanism of relaxation at
long distances is provided by random migration of the chaotic spots along the
chain, which bears analogy with variable-range hopping of electrons in strongly
disordered solids.
\\ ( http://arxiv.org/abs/1005.5033 , 195kb)
Date: Thu, 27 May 2010 11:46:23 GMT (597kb)

Title: Heisenberg-limited interferometry with pair coherent states and parity
Authors: Christopher C. Gerry and Jihane Mimih
Categories: quant-ph
   After reviewing parity measurement based interferometry with twin-Fock
states, which allows for super-sensitivity (Heisenberg-limited) and
super-resolution, we consider interferometry with two different superpositions
of twin-Fock states, namely two-mode squeezed vacuum states and pair coherent
states. This study is motivated by the experimental challenge of producing
twin-Fock states on opposite sides of a beam splitter. We find that input
two-mode squeezed states, while allowing for Heisenberg-limited sensitivity, do
not yield super-resolutions, whereas we that find both are possible with input
pair coherent states.
\\ ( http://arxiv.org/abs/1005.5038 , 597kb)
arXiv:1005.5139 (*cross-listing*)
Date: Thu, 27 May 2010 18:03:05 GMT (283kb,X)

Title: A Better Definition of the Kilogram
Authors: Ronald F. Fox, Theodore P. Hill, and Jack Miller
Categories: physics.data-an physics.pop-ph
Comments: 10 pages, no figures
   This article reviews several recent proposed redefinitions of the kilogram,
and compares them with respect to practical realizations, uncertainties
(estimated standard deviations), and educational aspects.
\\ ( http://arxiv.org/abs/1005.5139 , 283kb)
arXiv:1005.5174 (*cross-listing*)
Date: Thu, 27 May 2010 20:42:54 GMT (588kb)

Title: Spin transport in coupled spinor Bose gases
Authors: J.M. McGuirk
Categories: physics.atom-ph cond-mat.quant-gas
   We report direct measurements of spin transport in a trapped, partially
condensed spinor Bose gas. Detailed analyses of spin flux in this
out-of-equilibrium quantum gas are performed by monitoring the flow of atoms in
different hyperfine spin states. The main mechanisms for motion in this system
are exchange scattering and potential energy inhomogeneity, which lead to spin
waves in the normal component and domain formation in the condensate. We find a
large discrepancy in domain formation timescales with those predicted by
potential-driven formation, indicating strong coupling of the condensate to the
normal component spin wave.
\\ ( http://arxiv.org/abs/1005.5174 , 588kb)
Date: Fri, 28 May 2010 04:31:42 GMT (1228kb)

Title: Heating and Cooling in Adiabatic Mixing process
Authors: Jing Zhou, Zi Cai, Xu-Bo Zou, and Guang-Can Guo
Categories: cond-mat.quant-gas
Comments: 5 pages, 5 figures
   We study the effect of interaction on the temperature change in the process
of adiabatic mixing a two-component fermi gases by the real-space Bogoliubov-de
Gennes (BdG) method. We find that in the process of adiabatic mixing, the
competition of the adiabatic expansion and the attractive interaction make it
possible to cool or heal the system depending on strength interactions. The
change of temperature in a bulk system and a trapped system have been
investigated respectively.
\\ ( http://arxiv.org/abs/1005.5212 , 1228kb)
Date: Fri, 28 May 2010 07:08:09 GMT (504kb)

Title: Twenty Hirsch index variants and other indicators giving more or less
   preference to highly cited papers
Authors: Michael Schreiber
Categories: physics.soc-ph cs.DL
Comments: 19 pages, including 6 tables and 3 figures accepted for publication
   in Annalen der Physik Berlin
   The Hirsch index or h-index is widely used to quantify the impact of an
individual's scientific research output, determining the highest number h of a
scientist's papers that received at least h citations. Several variants of the
index have been proposed in order to give more or less preference to highly
cited papers. I analyse the citation records of 26 physicists discussing
various suggestions, in particular A, e, f, g, h(2), h_w, h_T, \hbar, m, {\pi},
R, s, t, w, and maxprod. The total number of all and of all cited publications
as well as the highest and the average number of citations are also compared.
Advantages and disadvantages of these indices and indicators are discussed.
Correlation coefficients are determined quantifying which indices and
indicators yield similar and which yield more deviating rankings of the 26
datasets. For 6 datasets the determination of the indices and indicators is
\\ ( http://arxiv.org/abs/1005.5227 , 504kb)
Date: Fri, 28 May 2010 12:01:12 GMT (2787kb)

Title: Weakly linked binary mixtures of F=1 87-Rb Bose-Einstein condensates
Authors: M. Mele-Messeguer, B. Julia-Diaz, M. Guilleumas, A. Polls and A.
Categories: cond-mat.quant-gas
Comments: 44 pages, 19 figures
   We present a study of binary mixtures of Bose-Einstein condensates confined
in a double-well potential within the framework of the mean field
Gross-Pitaevskii equation. We reexamine both the single component and the
binary mixture cases for such a potential, and we investigate in which
situations a simpler two-mode approach leads to an accurate description of
their dynamics. We also estimate the validity of the most usual dimensionality
reductions used to solve the Gross-Pitaevskii equations. To this end, we
compare both the semi-analytical two-mode approaches and the numerical
simulations of the 1D reductions with the full 3D numerical solutions of the
Gross-Pitaevskii equation. Our analysis provides a guide to clarify the
validity of several simplified models that describe mean field non-linear
dynamics, using an experimentally feasible binary mixture of an F=1 spinor
condensate with two of its Zeeman manifolds populated, m=+1 and m=-1.
\\ ( http://arxiv.org/abs/1005.5272 , 2787kb)
Date: Fri, 28 May 2010 12:50:10 GMT (27kb)

Title: Electromagnetic and phonon modes for superfluid He-4 with a disk
Authors: V.M. Loktev and M.D. Tomchenko
Categories: cond-mat.other
Comments: 9 pages, 1 figure
   We find the distribution of the electromagnetic field inside and outside a
dielectric disk resonator placed in He-II. It is shown that this field consists
of a collection of "circular" (c-) photons. The wave function \Psi_c of a
c-phonon for the He-II + disk system is calculated in the zero-order
approximation in interaction. Due to the symmetry of the problem, the structure
of \Psi_c is such that a c-phonon possesses, similarly to a c-photon of the
resonator, a definite energy and an angular momentum with respect to the disk
axis, but it does not possess a definite momentum in the disk plane.
\\ ( http://arxiv.org/abs/1005.5282 , 27kb)
Date: Fri, 28 May 2010 12:51:23 GMT (688kb,D)

Title: Generalized Hartree-Fock Theory for Interacting Fermions in Lattices:
   Numerical Methods
Authors: Christina V. Kraus and J. Ignacio Cirac
Categories: quant-ph
Comments: 16 pages, 22 figures
   We present numerical methods to solve the Generalized Hartree-Fock theory for
fermionic systems in lattices, both in thermal equilibrium and out of
equilibrium. Specifically, we show how to determine the covariance matrix
corresponding to the Fermionic Gaussian state that optimally approximates the
quantum state of the fermions. The methods apply to relatively large systems,
since their complexity only scales quadratically with the number of lattice
sites. Moreover, they are specially suited to describe inhomogenous systems, as
those typically found in recent experiments with atoms in optical lattices, at
least in the weak interaction regime. As a benchmark, we have applied them to
the two-dimensional Hubbard model on a 10x10 lattice with and without an
external confinement.
\\ ( http://arxiv.org/abs/1005.5284 , 688kb)
arXiv:1005.5306 (*cross-listing*)
Date: Fri, 28 May 2010 14:50:01 GMT (435kb)

Title: Feshbach resonances of harmonically trapped atoms
Authors: Philipp-Immanuel Schneider, Yulian V. Vanne, and Alejandro Saenz
Categories: cond-mat.quant-gas quant-ph
Comments: 4 pages, 3 figures
   Employing a short-range two-channel description we derive an analytic
equation for the eigenenergies and contribution of the resonant bound state
(RBS) of atoms in harmonic traps at a Feshbach resonance. On this basis we
obtain a new parameterization of the energy-dependent scattering length which
differs significantly from the one previously employed. We validate the model
by comparison with experiments and full numerical calculations for 6Li-87Rb.
Finally, we explore a new resonance phenomenon arising in traps -- a splitting
between the resonance and the maximal RBS admixture -- which is demonstrated to
have important impact on atom-loss processes.
\\ ( http://arxiv.org/abs/1005.5306 , 435kb)
Date: Fri, 28 May 2010 16:21:10 GMT (6kb)

Title: Proof of the Standard Quantum Limit for Monitoring Free-Mass Position
Authors: Seiji Kosugi
Categories: quant-ph
Comments: 4 pages, no figure
   The measurement result of the moved distance for a free mass m during the
time t between two position measurements cannot be predicted with uncertainty
smaller than sqrt{hbar t/2m}. This is formulated as a standard quantum limit
(SQL) and it has been proven to always hold for the following position
measurement: a probe is set in a prescribed position before the measurement.
Just after the interaction of the mass with the probe, the probe position is
measured, and using this value, the measurement results of the pre-measurement
and post-measurement positions are estimated.
\\ ( http://arxiv.org/abs/1005.5328 , 6kb)

The replacements:

replaced with revised version Sun, 23 May 2010 14:01:39 GMT (1390kb)

Title: Modulation of breathers in cigar-shaped Bose-Einstein condensates
Authors: W. B. Cardoso, A. T. Avelar, D. Bazeia
Categories: quant-ph cond-mat.quant-gas
Journal-ref: Physics Letters A,374(2010)2640-2645
DOI: 10.1016/j.physleta.2010.04.050
\\ ( http://arxiv.org/abs/0912.4011 , 1390kb)
arXiv:1005.1309 (*cross-listing*)
replaced with revised version Mon, 24 May 2010 21:06:29 GMT (1416kb)

Title: Suppression of Density Fluctuations in a Quantum Degenerate Fermi Gas
Authors: Christian Sanner, Edward J. Su, Aviv Keshet, Ralf Gommers, Yong-il
   Shin, Wujie Huang, Wolfgang Ketterle
Categories: cond-mat.quant-gas physics.atom-ph
Comments: minor edit: fixed technical problem with arxiv's processing of .eps
\\ ( http://arxiv.org/abs/1005.1309 , 1416kb)
replaced with revised version Tue, 25 May 2010 12:33:43 GMT (58kb,D)

Title: Three-body problem in heteronuclear mixtures with resonant interspecies
Authors: K. Helfrich, H.-W. Hammer, D.S. Petrov
Categories: cond-mat.quant-gas nucl-th
Comments: 13 pages, 8 figures, minor changes, published version
Report-no: HISKP-TH-09/36
Journal-ref: Phys.Rev.A81:042715,2010
DOI: 10.1103/PhysRevA.81.042715
\\ ( http://arxiv.org/abs/1001.4371 , 58kb)
replaced with revised version Tue, 25 May 2010 17:31:01 GMT (50kb)

Title: Wave functions of the super Tonks-Girardeau gas and the trapped 1D hard
   sphere Bose gas
Authors: M.D. Girardeau, G.E. Astrakharchik
Categories: cond-mat.quant-gas
Comments: 4 pages, 1 figure, revtex4. Final version accepted by Phys. Rev. A
   Rapid Communications
\\ ( http://arxiv.org/abs/0912.1633 , 50kb)
replaced with revised version Wed, 26 May 2010 00:43:42 GMT (485kb)

Title: Ground states and dynamics of population-imbalanced Fermi condensates in
   one dimension
Authors: Masaki Tezuka and Masahito Ueda
Categories: cond-mat.quant-gas cond-mat.str-el
Comments: 20 pages, 15 figures, accepted for publication in New Journal of
\\ ( http://arxiv.org/abs/1002.1433 , 485kb)
replaced with revised version Wed, 26 May 2010 06:33:44 GMT (696kb)

Title: Vortex structures and zero energy states in the BCS-to-BEC evolution of
   p-wave resonant Fermi gases
Authors: T. Mizushima, K. Machida
Categories: cond-mat.quant-gas cond-mat.supr-con
Comments: 15 pages, 9 figures, published version
Journal-ref: Phys. Rev. A 81, 053605 (2010)
\\ ( http://arxiv.org/abs/1001.5325 , 696kb)
replaced with revised version Wed, 26 May 2010 18:59:52 GMT (2277kb)

Title: Classical phases and quantum angles in the description of interfering
   Bose-Einstein condensates
Authors: W. J. Mullin and F. Lalo\"e
Categories: quant-ph
Comments: 35 pages, 22 figures
\\ ( http://arxiv.org/abs/0908.3012 , 2277kb)
replaced with revised version Thu, 27 May 2010 05:28:23 GMT (109kb)

Title: The stability of the low-dimensional mixtures of dilute quantum gases
Authors: Yu-Li Lee and Yu-Wen Lee
Categories: cond-mat.quant-gas cond-mat.other
Comments: 8 pages, several paragraphs have been completely rewritten, two
   figures and one reference are added
\\ ( http://arxiv.org/abs/0910.0603 , 109kb)
arXiv:0911.4564 (*cross-listing*)
replaced with revised version Thu, 27 May 2010 11:46:21 GMT (595kb)

Title: Spontaneous Four-Wave Mixing of de Broglie Waves: Beyond Optics
Authors: Valentina Krachmalnicoff (LCFIO), Jean-Christophe Jaskula (LCFIO),
   Marie Bonneau (LCFIO), Vanessa Leung (LCFIO), Guthrie B. Partridge (LCFIO),
   Denis Boiron (LCFIO), Christoph I Westbrook (LCFIO), Piotr Deuar, Pawel Zin,
   Marek Trippenbach, Karen Kheruntsyan
Categories: cond-mat.quant-gas quant-ph
\\ ( http://arxiv.org/abs/0911.4564 , 595kb)
replaced with revised version Thu, 27 May 2010 13:25:42 GMT (132kb,D)

Title: First and second sound in cylindrically trapped gases
Authors: G. Bertaina, L. Pitaevskii, S. Stringari
Categories: cond-mat.quant-gas
Comments: 4 pages, 2 figures. Paper reformatted, more emphasis on role of
   viscosity and thermal conductivity in the long wave length limit, new damping
   effect of non dissipative nature identified in second sound above Tc. New
   figures presented
\\ ( http://arxiv.org/abs/1002.0195 , 132kb)
replaced with revised version Thu, 27 May 2010 20:41:18 GMT (477kb,D)

Title: A superfluid-droplet crystal and a free-space supersolid in a
   dipole-blockaded gas
Authors: F. Cinti, P. Jain, M. Boninsegni, A. Micheli, P. Zoller, and G.
Categories: cond-mat.quant-gas cond-mat.stat-mech
Comments: 4 pages, 4 figures
\\ ( http://arxiv.org/abs/1005.2403 , 477kb)
replaced with revised version Fri, 28 May 2010 04:36:21 GMT (1164kb)

Title: Continuous-variables entanglement purification with atomic systems
Authors: Stojan Rebic, Stefano Mancini, Giovanna Morigi and David Vitali
Categories: quant-ph
Comments: Published in Feature Issue "Quantum Optical Information Technologies"
Journal-ref: J. Opt. Soc. Am. B 27, A198 (2010)
\\ ( http://arxiv.org/abs/0912.2402 , 1164kb)
replaced with revised version Fri, 28 May 2010 14:39:47 GMT (487kb)

Title: Spin self-rephasing and very long coherence times in a trapped atomic
Authors: Christian Deutsch, Fernando Ramirez-Martinez, Clement Lacro\^ute,
   Friedemann Reinhard, Tobias Schneider, Jean-No\"el Fuchs, Fr\'ed\'eric
   Pi\'echon, Franck Lalo\"e, Jakob Reichel and Peter Rosenbusch
Categories: quant-ph physics.atom-ph
Comments: Revised version; improved description of the theoretical treatment
\\ ( http://arxiv.org/abs/1003.5925 , 487kb)

Till next time,

Dr M. J. Davis,                      Associate Professor in Physics
School of Mathematics and Physics,   ph  : +61 7 334 69824
The University of Queensland,        fax : +61 7 336 51242
Brisbane, QLD 4072,                  mdavis_at_physics.uq.edu.au
Australia.                           www.physics.uq.edu.au/people/mdavis/
Matt's arXiv selection: weekly summary of cold-atom papers from arXiv.org
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Received on Wed Aug 04 2010 - 09:32:19 EST

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