# Matt's arXiv selection: week ending 14 December 2007

From: Matthew Davis <mdavis_at_physics.uq.edu.au>
Date: Fri, 21 Dec 2007 21:48:29 +1000

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

Hi all,

Last week was another busy week, with 31 new abstracts and 16 replacements.

I'm officially up-to-date! Yah!

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arXiv:0712.1153
Date: Fri, 7 Dec 2007 14:52:05 GMT (374kb)

Title: Superfluidity of $^4$He Confined in Nano-Porous Media
Authors: Keiya Shirahama, Keiichi Yamamoto, Yoshiyuki Shibayama
Categories: cond-mat.mes-hall cond-mat.str-el
Comments: 6 Pages, 6 Figures, Submitted to "Helium: 100 years", Special Issue
of Low Temperature Physics
\\
We have examined superfluid properties of $^4$He confined to a nano-porous
Gelsil glass that has nanopores 2.5 nm in diameter. The pressure-temperature
phase diagram was determined by torsional oscillator, heat capacity and
pressure studies. The superfluid transition temperature $T_{\mathrm c}$
approaches zero at 3.4 MPa, indicating a novel "quantum" superfluid transition.
By heat capacity measurements, the nonsuperfluid phase adjacent to the
superfluid and solid phases is identified to be a nanometer-scale, localized
Bose condensation state, in which global phase coherence is destroyed. At high
pressures, the superfluid density has a $T$-linear term, and $T_{\mathrm c}$ is
proportional to the zero-temperature superfluid density. These results strongly
suggest that phase fluctuations in the superfluid order parameter play a
dominant role on the phase diagram and superfluid properties.
\\ ( http://arxiv.org/abs/0712.1153 , 374kb)
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arXiv:0712.1154
Date: Fri, 7 Dec 2007 15:09:38 GMT (383kb)

Title: Many-Body Physics and Quantum Chaos
Authors: Denis Ullmo
Categories: cond-mat.mes-hall
Comments: To appear in Rep. Prog. Phys
\\
Experimental progresses in the miniaturisation of electronic devices have
made routinely available in the laboratory small electronic systems, on the
micron or sub-micron scale, which at low temperature are sufficiently well
isolated from their environment to be considered as fully coherent. Some of
their most important properties are dominated by the interaction between
electrons. Understanding their behaviour therefore requires a description of
the interplay between interference effects and interactions.
The goal of this review is to address this relatively broad issue, and more
specifically to address it from the perspective of the quantum chaos community.
I will therefore present some of the concepts developed in the field of quantum
chaos which have some application to study many-body effects in mesoscopic and
nanoscopic systems. Their implementation is illustrated on a few examples of
experimental relevance such as persistent currents, mesoscopic fluctuations of
Kondo properties or Coulomb blockade. I will furthermore try to bring out, from
the various physical illustrations, some of the specific advantages on more
general grounds of the quantum chaos based approach.
\\ ( http://arxiv.org/abs/0712.1154 , 383kb)
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arXiv:0712.1213
Date: Fri, 7 Dec 2007 19:14:47 GMT (517kb)

Title: Relaxation phenomena at criticality
Authors: Andrea Gambassi
Categories: cond-mat.stat-mech
Comments: Talk delivered at Statphys23, Genova, Italy, July 9-13, 2007. 8
pages, 7 figures
\\
The collective behaviour of statistical systems close to critical points is
characterized by an extremely slow dynamics which, in the thermodynamic limit,
eventually prevents them from relaxing to an equilibrium state after a change
in the thermodynamic control parameters. The non-equilibrium evolution
following this change displays some of the features typically observed in
glassy materials, such as ageing, and it can be monitored via dynamic
susceptibilities and correlation functions of the order parameter, the scaling
behaviour of which is characterized by universal exponents, scaling functions,
and amplitude ratios. This universality allows one to calculate these
quantities in suitable simplified models and field-theoretical methods are a
natural and viable approach for this analysis. In addition, if a statistical
system is spatially confined, universal Casimir-like forces acting on the
confining surfaces emerge and they build up in time when the temperature of the
system is tuned to its critical value. We review here some of the theoretical
results that have been obtained in recent years for universal quantities, such
as the fluctuation-dissipation ratio, associated with the non-equilibrium
critical dynamics, with particular focus on the Ising model with Glauber
dynamics in the bulk. The non-equilibrium dynamics of the Casimir force acting
in a film is discussed within the Gaussian model.
\\ ( http://arxiv.org/abs/0712.1213 , 517kb)
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arXiv:0712.0986 (*cross-listing*)
Date: Thu, 6 Dec 2007 16:26:08 GMT (777kb)

Title: Matter-wave solitons for a periodic piecewise-constant nonlinearity
Authors: A. S. Rodrigues, P. G. Kevrekidis, Mason A. Porter, D. J.
Frantzeskakis, P. Schmelcher, and A. R. Bishop
Categories: nlin.PS cond-mat.other math.DS physics.atom-ph
Comments: 24 pages (preprint form), 7 figures (some with multiple parts)
\\
Motivated by recent proposals of collisionally inhomogeneous''
Bose-Einstein condensates (BECs), which have a spatially modulated scattering
length, we study the existence and stability properties of bright and dark
matter-wave solitons of a BEC characterized by a piecewise constant scattering
length. We use a stitching'' approach to analytically approximate the
pertinent solutions of the underlying nonlinear Schr\"odinger equation, by
matching the wavefunction and its derivatives at the interfaces of the
nonlinearity coefficient. General tools from the theory of perturbed
Hamiltonian systems are adapted to accurately quantify the stability of bright
and dark solitons. It is shown that solitons can only exist at the center of
the regions of the piecewise constant nonlinearity. In the case of bright
solitons stable and unstable configurations are possible whereas for dark
solitons all solitons are unstable, although through different mechanisms
depending on the soliton location. The analytical results are corroborated by
the findings of numerical computations.
\\ ( http://arxiv.org/abs/0712.0986 , 777kb)
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arXiv:0712.1257
Date: Sat, 8 Dec 2007 03:24:27 GMT (251kb)

Title: Quasi-energies and Floquet states of two weakly coupled Bose-Einstein
condensates under periodic driving
Authors: Xiaobing Luo, Qiongtao Xie, and Biao Wu
Categories: cond-mat.other
\\
We investigate the quasi-energies and Floquet states of two weakly coupled
Bose-Einstein condensates driven by a periodic force. The quasi-energies and
Floquet states of this system are computed within two different theoretical
frameworks: the mean-field model and the second-quantized model. The mean-field
approach reveals a triangular structure in the quasi-energy band. Our analysis
of the corresponding Floquet states shows that this triangle signals the onset
of a localization phenomenon, which can be regarded as a generalization of the
well-known phenomenon called coherent destruction of tunneling. With the second
quantized model, we find also a triangular structure in the quantum
quasi-energy band, which is enveloped by the mean-field triangle. The close
relation between these two sets of quasi-energies is further explored by a
semi-classical method. With a Sommerfeld rule generalized to time-dependent
systems, the quantum quasi-energies are computed by quantizing semiclassically
the mean-field model and they are found to agree very well with the results
obtained directly with the second-quantized model.
\\ ( http://arxiv.org/abs/0712.1257 , 251kb)
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arXiv:0712.1265
Date: Sat, 8 Dec 2007 07:50:51 GMT (196kb)

Title: The trapped two-dimensional Bose gas: from Bose-Einstein condensation to
Berezinskii-Kosterlitz-Thouless physics
Authors: Zoran Hadzibabic (LKB - Lhomond), Peter Kr\"uger (LKB - Lhomond), Marc
Cheneau (LKB - Lhomond), Steffen Patrick Rath (LKB - Lhomond), Jean Dalibard
(LKB - Lhomond)
Categories: cond-mat.other
Proxy: ccsd hal-00194992
\\
We analyze the results of a recent experiment with bosonic rubidium atoms
harmonically confined in a quasi-two-dimensional geometry. In this experiment a
well defined critical point was identified, which separates the
high-temperature normal state characterized by a single component density
distribution, and the low-temperature state characterized by a bimodal density
distribution and the emergence of high-contrast interference between
independent two-dimensional clouds. We first show that this transition cannot
be explained in terms of conventional Bose-Einstein condensation of the trapped
ideal Bose gas. Using the local density approximation, we then present a hybrid
approach, combining the mean-field (MF) Hartree-Fock theory with the prediction
for the Berezinskii-Kosterlitz-Thouless transition in an infinite uniform
system. We compare the MF results with those of a recent Quantum Monte-Carlo
(QMC) analysis. For the considered experiment, both approaches lead to a strong
and similar correction to the critical atom number with respect to the ideal
gas theory (factor $\sim 2$). The spatial density profiles obtained using the
QMC method significantly deviate from the MF prediction, and a similar
deviation is observed in the experiment. This suggests that beyond mean-field
effects can play a significant role at the critical point in this geometry. A
quantitative agreement between theory and experiment can be reached concerning
the critical atom number if the QMC results are used for temperature
calibration.
\\ ( http://arxiv.org/abs/0712.1265 , 196kb)
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arXiv:0712.1399
Date: Mon, 10 Dec 2007 06:24:40 GMT (92kb)

Title: Correlation functions of an interacting spinless fermion model at finite
temperature
Authors: Kohei Motegi, Kazumitsu Sakai
Categories: cond-mat.stat-mech
\\
We formulate correlation functions for a one-dimensional interacting spinless
fermion model at finite temperature. By combination of a lattice path integral
formulation for thermodynamics with the algebraic Bethe ansatz for fermion
systems, the equal-time one-particle Green's function at arbitrary particle
density is expressed as a multiple integral form. Our formula reproduces
previously known results in the following three limits: the zero-temperature,
the infinite-temperature and the free fermion limits.
\\ ( http://arxiv.org/abs/0712.1399 , 92kb)
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arXiv:0712.1445
Date: Mon, 10 Dec 2007 12:08:54 GMT (569kb,D)

Title: Universal Thermodynamics of a Strongly Interacting Molecular Condensate
Authors: Yasuhisa Inada, Munekazu Horikoshi, Shuta Nakajima, Makoto
Kuwata-Gonokami, Masahito Ueda and Takashi Mukaiyama
Categories: cond-mat.other
\\
The unitarity limit of the critical temperature and the universal curve of
the condensate fraction have been observed for a molecular Bose-Einstein
condensate of fermionic $^6$Li atoms. The Bragg spectroscopy is employed to
precisely determine the temperature of such strongly interacting molecules that
the bimodality of the gas is completely smeared out in real space. The
molecular scattering length deduced from release energy measurement agrees with
the value calculated for tightly bound molecules and only begins to deviate
linearly from that value upon the onset of unitarity.
\\ ( http://arxiv.org/abs/0712.1445 , 569kb)
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arXiv:0712.1448
Date: Mon, 10 Dec 2007 11:46:35 GMT (235kb)

Title: Excitations in two-component Bose-gases
Authors: Adrian Kleine, Corinna Kollath, Ian P. McCulloch, Thierry Giamarchi,
Ulrich Schollwoeck
Categories: cond-mat.stat-mech
\\
In this paper, we study a strongly correlated quantum system that has become
amenable to experiment by the advent of ultracold bosonic atoms in optical
lattices, a chain of two different bosonic constituents. Excitations in this
system are first considered within the framework of bosonization and Luttinger
liquid theory which are applicable if the Luttinger liquid parameters are
determined numerically. The occurrence of a bosonic counterpart of fermionic
spin-charge separation is signalled by a characteristic two-peak structure in
the spectral functions found by dynamical DMRG in good agreement with
analytical predictions. Experimentally, single-particle excitations as probed
by spectral functions are currently not accessible in cold atoms. We therefore
consider the modifications needed for current experiments, namely the
investigation of the real-time evolution of density perturbations instead of
single particle excitations, a slight inequivalence between the two
intraspecies interactions in actual experiments, and the presence of a
confining trap potential. Using time-dependent DMRG we show that only
quantitative modifications occur. With an eye to the simulation of strongly
correlated quantum systems far from equilibrium we detect a strong dependence
of the time-evolution of entanglement entropy on the initial perturbation,
signalling limitations to current reasonings on entanglement growth in
many-body systems.
\\ ( http://arxiv.org/abs/0712.1448 , 235kb)
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arXiv:0712.1482
Date: Mon, 10 Dec 2007 14:06:34 GMT (701kb)

Title: Guided atom laser : a new tool for guided atom optics
Authors: J. Billy (LCFIO), V. Josse (LCFIO), Z. Zuo (LCFIO), A. Aspect (LCFIO),
Philippe Bouyer (LCFIO)
Categories: cond-mat.other
Proxy: ccsd hal-00195321
\\
We present a guided atom laser. A Bose-Einstein condensate (BEC) is created
in a crossed hybrid magnetic and an elongated optical trap, which acts as a
matterwave guide. Atoms are extracted from the BEC by radio frequency (rf)
outcoupling and then guided in the horizontal optical matterwave guide. This
method allows to control the acceleration of the beam and to achieve large de
Broglie wavelength. We also measure the longitudinal energy of the guided atom
laser using atom optical elements based on a blue light barrier.
\\ ( http://arxiv.org/abs/0712.1482 , 701kb)
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arXiv:0712.1543
Date: Mon, 10 Dec 2007 17:26:57 GMT (493kb)

Title: Quantum-limited position measurements of a dark matter-wave soliton
Authors: Antonio Negretti, Carsten Henkel, and Klaus Molmer
Categories: quant-ph
Comments: RevTex4, 4 pages, 1 figure. Submitted to Phys. Rev. Lett
\\
We show that the position of a dark matter wave soliton can be determined
with a precision that scales with the atomic density as n^{-3/4}. This
surpasses the standard shot noise detection limit for independent particles,
without use of squeezing and entanglement, and it suggests that interactions
among particles may present new advantages in high precision metrology.
\\ ( http://arxiv.org/abs/0712.1543 , 493kb)
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arXiv:0712.1526
Date: Mon, 10 Dec 2007 16:09:17 GMT (240kb)

Title: Cold SO_2 molecules by Stark deceleration
Authors: O. Bucicov, M. Nowak, S. Jung, G. Meijer, E. Tiemann, Ch. Lisdat
Categories: physics.atom-ph
\\
We produce SO_2 molecules with a centre of mass velocity near zero using a
Stark decelerator. Since the initial kinetic energy of the supersonic SO_2
molecular beam is high, and the removed kinetic energy per stage is small, 326
deceleration stages are necessary to bring SO_2 to a complete standstill,
significantly more than in other experiments. We show that in such a
decelerator possible loss due to coupling between the motional degrees of
freedom must be considered. Experimental results are compared with 3D
Monte-Carlo simulations and the quantum state selectivity of the Stark
decelerator is demonstrated.
\\ ( http://arxiv.org/abs/0712.1526 , 240kb)
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arXiv:0712.1367
Date: Sun, 9 Dec 2007 21:08:45 GMT (485kb)

Title: Planck, Photon Statistics, and Bose-Einstein Condensation
Authors: Daniel M. Greenberger, Noam Erez, Marlan O. Scully, Anatoly A.
Svidzinsky, M. Suhail Zubairy
Categories: physics.optics physics.hist-ph
Comments: Review paper, 58 pages, 10 figures
Journal-ref: Progress in Optics, vol. 50, edited by E. Wolf, Elsevier,
Amsterdam, 275-330 (2007)
\\
The interplay between optical and statistical physics is a rich and exciting
field of study. Black body radiation was the first application of photon
statistics, although it was initially treated as a problem of the cavity
oscillators in equilibrium with the photon field. However Planck surprisingly
resisted the idea that anything physical would be quantized for a long time
after he had solved the problem. We trace this development.
Then, after the invention of the laser itself, it proved difficult to develop
a theory of laser action that could account for photon statistics, i.e.
fluctuations near threshold. This was accomplished in 1965. After Bose-Einstein
condensation was successfully achieved, the same problem arose in this case.
The fluctuation problem had not been treated adequately even for the ideal Bose
gas. However this problem has now been solved using the same techniques as in
the theory of laser action.
\\ ( http://arxiv.org/abs/0712.1367 , 485kb)
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arXiv:0712.1677
Date: Tue, 11 Dec 2007 10:56:21 GMT (44kb)

Title: Quasi-relativistic behavior of cold atoms in light fields
Authors: G. Juzeliunas, J. Ruseckas, M. Lindberg, L. Santos and P. Ohberg
Categories: cond-mat.mes-hall
\\
We study the influence of three laser beams on the center of mass motion of
cold atoms with internal energy levels in a tripod configuration. We show that
similar to electrons in graphene the atomic motion can be equivalent to the
dynamics of ultra-relativistic two-component Dirac fermions. We propose and
analyze an experimental setup for observing such a quasi-relativistic motion of
ultracold atoms. We demonstrate that the atoms can experience negative
refraction and focussing by Veselago-type lenses. We also show how the chiral
nature of the atomic motion manifests itself as an oscillation of the atomic
internal state population which depends strongly on the direction of the center
of mass motion. For certain directions an atom remains in its initial state,
whereas for other directions the populations undergo oscillations between a
pair of internal states.
\\ ( http://arxiv.org/abs/0712.1677 , 44kb)
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arXiv:0712.1696
Date: Tue, 11 Dec 2007 12:27:06 GMT (87kb)

Title: Mott-Hubbard Transition of Bosons in Optical Lattices with Three-body
Interactions
Authors: Bo-lun Chen, Xiao-bin Huang, Su-peng Kou and Yunbo Zhang
Categories: cond-mat.mes-hall cond-mat.str-el
\\
In this paper, the quantum phase transition between superfluid state and
Mott-insulator state is studied based on an extended Bose-Hubbard model with
two- and three-body on-site interactions. Using the mean-field approximation we
find the extension of the insulating 'lobes' and the existence of a fixed point
in three dimensional phase space. We investigate the link between experimental
parameters and theoretical variables. The possibility to obverse our results
through some experimental effects in optically trapped Bose-Einstein
Condensates(BEC) is also discussed.
\\ ( http://arxiv.org/abs/0712.1696 , 87kb)
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arXiv:0712.1745
Date: Tue, 11 Dec 2007 15:53:43 GMT (126kb)

Title: Phenomenological description of the vortex density in rotating BEC
superfluids
Authors: Michele Sciacca, David Jou and Maria Stella Mongiov\'i
Categories: cond-mat.other
\\
We propose a phenomenological equation for the vortex line density in
rotating Bose-Einstein condensates as a function of the angular speed. This
equation provides a simple description of the gross features of the increase in
vortex number from the appearance of the first vortex to the theoretical
rigid-body result for high vortex density, and allows one to compare with
analogous situations in superfluid helium, after the suitable changes in the
\\ ( http://arxiv.org/abs/0712.1745 , 126kb)
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arXiv:0712.1657
Date: Tue, 11 Dec 2007 07:07:45 GMT (352kb)

Title: Entangling the ro-vibrational modes of a macroscopic mirror using
Authors: M. Bhattacharya, P.-L. Giscard, and P. Meystre
Categories: quant-ph
\\
We consider the dynamics of a vibrating and rotating end-mirror of an optical
Fabry-P{\'erot} cavity that can sustain Laguerre-Gaussian modes. We demonstrate
theoretically that since the intra-cavity field carries linear as well as
angular momentum, radiation pressure can create bipartite entanglement between
a vibrational and a rotational mode of the mirror. Further we show that the
ratio of vibrational and rotational couplings with the radiation field can
easily be adjusted experimentally, which makes the generation and detection of
entanglement robust to uncertainties in the cavity manufacture. This
constitutes the first proposal to demonstrate entanglement between two
qualitatively different degrees of freedom of the same macroscopic object.
\\ ( http://arxiv.org/abs/0712.1657 , 352kb)
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arXiv:0712.1805
Date: Tue, 11 Dec 2007 19:58:53 GMT (616kb)

Title: Quantum control of EIT dispersion via atomic tunneling in a double-well
Bose-Einstein condensate
Authors: James Owen Weatherall, Christopher P. Search, and Markku Jaaskelainen
Categories: quant-ph
\\
Electromagnetically induced transparency (EIT) is an important tool for
controlling light propagation and nonlinear wave mixing in atomic gases with
potential applications ranging from quantum computing to table top tests of
general relativity. Here we consider EIT in an atomic Bose-Einstein Condensate
(BEC) trapped in a double well potential. A weak probe laser propagates through
one of the wells and interacts with atoms in a three-level $\Lambda$
configuration. The well through which the probe propagates is dressed by a
strong control laser with Rabi frequency $\Omega_{\mu}$, as in standard EIT
systems. Tunneling between the wells at the frequency $g$ provides a coherent
coupling between identical electronic states in the two wells, which leads to
the formation of inter-well dressed states. The tunneling in conjunction with
the macroscopic interwell coherence of the BEC wave function, results in the
formation of two ultra-narrow absorption resonances for the probe field that
are inside of the ordinary EIT transparency window. We show that these new
resonances can be interpreted in terms of the inter-well dressed states and the
formation of a novel type of dark state involving the control laser and the
inter-well tunneling. To either side of these ultra-narrow resonances there is
normal dispersion with very large slope controlled by $g$. For realistic values
of $g$, the large slope of this dispersion yields group velocities for the
probe field that are two orders of magnitude slower than standard EIT systems.
We discuss prospects for observing these ultra-narrow resonances and the
corresponding regions of high dispersion experimentally.
\\ ( http://arxiv.org/abs/0712.1805 , 616kb)
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arXiv:0712.1773
Date: Tue, 11 Dec 2007 17:08:51 GMT (302kb)

Title: Collective Atomic Recoil Laser as a synchronization transition
Authors: J. Javaloyes, M. Perrin, A. Politi
Categories: physics.optics physics.gen-ph
\\
We consider here a model previously introduced to describe the collective
behavior of an ensemble of cold atoms interacting with a coherent
electromagnetic field. The atomic motion along the self-generated
spatially-periodic force field can be interpreted as the rotation of a phase
oscillator. This suggests a relationship with synchronization transitions
occurring in globally coupled rotators. In fact, we show that whenever the
field dynamics can be adiabatically eliminated, the model reduces to a
self-consistent equation for the probability distribution of the atomic
"phases". In this limit, there exists a formal equivalence with the Kuramoto
model, though with important differences in the self-consistency conditions.
Depending on the field-cavity detuning, we show that the onset of synchronized
behavior may occur through either a first- or second-order phase transition.
Furthermore, we find a secondary threshold, above which a periodic self-pulsing
regime sets in, that is immediately followed by the unlocking of the
forward-field frequency. At yet higher, but still experimentally meaningful,
input intensities, irregular, chaotic oscillations may eventually appear.
Finally, we derive a simpler model, involving only five scalar variables, which
is able to reproduce the entire phenomenology exhibited by the original model.
\\ ( http://arxiv.org/abs/0712.1773 , 302kb)
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arXiv:0712.1817
Date: Tue, 11 Dec 2007 21:00:26 GMT (145kb)

Title: Crystallization of strongly interacting photons in a nonlinear optical
fiber
Authors: D.E. Chang, V. Gritsev, G. Morigi, V. Vuletic, M.D. Lukin, and E.A.
Demler
Categories: cond-mat.other
\\
Understanding strongly correlated quantum systems is a central problem in
many areas of physics. The collective behavior of interacting particles gives
rise to diverse fundamental phenomena such as confinement in quantum
chromodynamics, phase transitions, and electron fractionalization in the
quantum Hall regime. While such systems typically involve massive particles,
optical photons can also interact with each other in a nonlinear medium. In
practice, however, such interactions are often very weak. Here we describe a
novel technique that allows the creation of a strongly correlated quantum gas
of photons using one-dimensional optical systems with tight field confinement
and coherent photon trapping techniques. The confinement enables the generation
of large, tunable optical nonlinearities via the interaction of photons with a
nearby cold atomic gas. In its extreme, we show that a quantum light field can
undergo fermionization in such one-dimensional media, which can be probed via
standard photon correlation measurements.
\\ ( http://arxiv.org/abs/0712.1817 , 145kb)
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arXiv:0712.1828
Date: Wed, 12 Dec 2007 06:50:21 GMT (509kb,D)

Title: Superfluid-insulator transition in Fermi-Bose mixtures and the
orthogonality catastrophe
Authors: Gil Refael, Eugene Demler
Categories: cond-mat.supr-con
\\
The superfluid-insulator transition of bosons is strongly modified by the
presence of Fermions. Through an imaginary-time path integral approach, we
derive the self-consistent mean-field transition line, and account for both the
static and the dynamic screening effects of the fermions. We find that an
effect akin to the fermionic orthogonality catastrophe, arising from the
fermionic screening fluctuations, suppresses superfluidity. We analyze this
effect for various mixture parameters and temperatures, and consider possible
signatures of the orthogonality catastrophe effect in other measurables of the
mixture.
\\ ( http://arxiv.org/abs/0712.1828 , 509kb)
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arXiv:0712.1853
Date: Wed, 12 Dec 2007 01:37:38 GMT (867kb,D)

Title: Time-resolved Observation and Control of Superexchange Interactions with
Ultracold Atoms in Optical Lattices
Authors: S. Trotzky, P. Cheinet, S. F\"olling, M. Feld, U. Schnorrberger, A. M.
Rey, A. Polkovnikov, E. A. Demler, M. D. Lukin and I. Bloch
Categories: cond-mat.other
\\
Quantum mechanical superexchange interactions form the basis of quantum
magnetism in strongly correlated electronic media. We report on the direct
measurement of superexchange interactions with ultracold atoms in optical
lattices. After preparing a spin-mixture of ultracold atoms in an
antiferromagnetically ordered state, we measure a coherent
superexchange-mediated spin dynamics with coupling energies from 5 Hz up to 1
kHz. By dynamically modifying the potential bias between neighboring lattice
sites, the magnitude and sign of the superexchange interaction can be
controlled, thus allowing the system to be switched between antiferromagnetic
or ferromagnetic spin interactions. We compare our findings to predictions of a
two-site Bose-Hubbard model and find very good agreement, but are also able to
identify corrections which can be explained by the inclusion of direct
nearest-neighbor interactions.
\\ ( http://arxiv.org/abs/0712.1853 , 867kb)
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arXiv:0712.1860
Date: Wed, 12 Dec 2007 03:18:46 GMT (282kb)

Title: Integrability, stability, and adiabaticity in nonlinear stimulated Raman
Authors: A.P.Itin and S.Watanabe
Categories: cond-mat.other
Comments: Presented on QUAMP-4 conference (UCL, London); 4 pages; bibliography
is slightly extended as compared to a version published in PRL
Journal-ref: Phys. Rev. Lett. 99, 223903 (2007)
DOI: 10.1103/PhysRevLett.99.223903
\\
We study dynamics of a two-color photoassociation of atoms into diatomic
molecules via nonlinear Stimulated Raman adiabatic passage (STIRAP) process.
This system has a famous counterpart in (linear) quantum mechanics, and been
discussed recently in the context of generalizing quantum adiabatic theorem to
nonlinear systems. Here we use another approach to study adiabaticity and
stability in the system: we apply methods of classical Hamiltonian dynamics. We
found nonlinear dynamical instabilities, cases of complete integrability, and
\\ ( http://arxiv.org/abs/0712.1860 , 282kb)
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arXiv:0712.1891
Date: Wed, 12 Dec 2007 11:09:56 GMT (178kb,D)

Title: Stabilization of Solitons Generated by a Supersonic Flow of
Bose-Einstein Condensate Past an Obstacle
Authors: A.M. Kamchatnov, L.P. Pitaevskii
Categories: cond-mat.other
\\
Stability of dark solitons generated by a supersonic flow of Bose-Einstein
condensate past an obstacle is investigated. It is shown that in the reference
frame attached to the obstacle a transition occurs at some critical value of
the flow velocity from absolute instability of dark solitons to their
convective instability. This leads to decay of disturbances of solitons at
fixed distance from the obstacle and formation of effectively stable dark
solitons. This phenomenon explains surprising stability of the flow picture
that has been observed in numerical simulations.
\\ ( http://arxiv.org/abs/0712.1891 , 178kb)
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arXiv:0712.1856
Date: Wed, 12 Dec 2007 02:16:40 GMT (340kb)

Title: Tunneling phase gate for neutral atoms in a double-well lattice
Authors: Frederick W. Strauch, Mark Edwards, Eite Tiesinga, Carl Williams,
Charles W. Clark
Categories: quant-ph
\\
We propose a new two--qubit phase gate for ultra--cold atoms confined in an
experimentally realized tilted double--well optical lattice [Sebby--Strabley et
al., Phys. Rev. A {\bf 73} 033605 (2006)]. Such a lattice is capable of
confining pairs of atoms in a two--dimensional array of double--well potentials
where control can be exercised over the barrier height and the energy
difference of the minima of the two wells (known as the tilt''). The four
lowest single--particle motional states consist of two pairs of motional states
in which each pair is localized on one side of the central barrier, allowing
for two atoms confined in such a lattice to be spatially separated qubits. We
present a time--dependent scheme to manipulate the tilt to induce tunneling
oscillations which produce a collisional phase gate. Numerical simulations
demonstrate that this gate can be performed with high fidelity.
\\ ( http://arxiv.org/abs/0712.1856 , 340kb)
------------------------------------------------------------------------------
\\
arXiv:0712.1990
Date: Wed, 12 Dec 2007 17:46:23 GMT (362kb)

Title: Atom Interferometry with up to 24-Photon-Momentum-Transfer Beam
Splitters
Authors: Holger Mueller, Sheng-wey Chiow, Quan Long, Sven Herrmann, and Steven
Chu
Categories: physics.atom-ph physics.optics
\\
We present multi- (up to 24-)photon Bragg diffraction as beam splitter to
achieve the largest splitting in momentum space in any light-pulse atom
interferometer thus far. Relative to the 2-photon processes used in the most
sensitive present interferometers, these large momentum transfer beam splitters
increase the phase shift 12-fold for Mach-Zehnder and 144-fold for Ramsey-Borde
geometries. As the atom's internal state is not changed, important systematic
effects can cancel. This dramatic increase in sensitivity and precision opens
the door to improved measurements of the fine-structure constant, inertial
forces, and tests of relativity and quantum electrodynamics.
\\ ( http://arxiv.org/abs/0712.1990 , 362kb)
------------------------------------------------------------------------------
\\
arXiv:0712.2121
Date: Thu, 13 Dec 2007 10:25:39 GMT (431kb)

Title: Mode Locking of Exciton-Polariton Condensates in the Presence of
Disorder
Authors: A. Baas, K. G. Lagoudakis, M. Richard, R. Andre, Le Si Dang, B.
Deveaud-Pledran
Categories: cond-mat.other
\\
Condensation of exciton-polaritons in semiconductor microcavities takes place
despite in plane disorder. Below the critical density the inhomogeneity of the
potential seen by the polaritons strongly limits the spatial extension of the
ground state. This limitation can be overcome above the critical density thanks
to a non linear coupling, resulting in a mode locking effect. This is clearly
evidenced by spatial and spectral studies, coupled to interferometric
measurements. In case of strong disorder, several non mode-locked independent
condensates can be evidenced, which present accordingly the expected lack of
phase locking. The transition from dependent to independent condensates is
addressed considering multiple realizations of the disorder.
\\ ( http://arxiv.org/abs/0712.2121 , 431kb)
------------------------------------------------------------------------------
\\
arXiv:0712.2128
Date: Thu, 13 Dec 2007 11:01:58 GMT (15kb)

Title: Functional-integral representation of atomic mixtures
Authors: O. Fialko and K. Ziegler
Categories: cond-mat.other
Comments: 6 pages, 5 figures, contribution to 'Path Integrals, Dresden 2007'
\\
A mixture of spin-1/2 fermionic atoms and molecules of paired fermionic atoms
is studied in an optical lattice. The molecules are formed by an attractive
nearest-neighbor interaction. A functional integral is constructed for this
many-body system and analyzed in terms of a mean-field approximation and
Gaussian fluctuations. This provides a phase diagram with the two merging Mott
insulators and an intermediate superfluid. The Gaussian fluctuations give rise
to an induced repulsive dimer-dimer interaction mediated by the unpaired
fermions. The effect of an unbalanced distribution of spin-up and spin-down
fermions is also discussed.
\\ ( http://arxiv.org/abs/0712.2128 , 15kb)
------------------------------------------------------------------------------
\\
arXiv:0712.2145
Date: Thu, 13 Dec 2007 12:55:59 GMT (592kb)

Title: Atomic four-wave mixing via condensate collisions
Authors: Aur\'elien Perrin (LCFIO), Craig M. Savage, D. Boiron (LCFIO), V.
Krachmalnicoff (LCFIO), C. I. Westbrook (LCFIO), Karen Kheruntsyan
Categories: quant-ph
Proxy: ccsd hal-00196633
\\
We perform a theoretical analysis of atomic four-wave mixing via a collision
of two Bose-Einstein condensates of metastable helium atoms, and compare the
results to a recent experiment. We calculate atom-atom pair correlations within
the scattering halo produced spontaneously during the collision. We also
examine the expected relative number squeezing of atoms on the sphere. The
analysis includes first-principles quantum simulations using the positive
P-representation method. We develop a unified description of the experimental
and simulation results.
\\ ( http://arxiv.org/abs/0712.2145 , 592kb)
------------------------------------------------------------------------------
\\
arXiv:0712.2057
Date: Wed, 12 Dec 2007 22:44:10 GMT (542kb)

Title: Theoretical analysis of a single and double reflection atom
interferometer in a weakly-confining magnetic trap
Authors: James A. Stickney, Rudra P. Kafle, Dana Z. Anderson, Alex A. Zozulya
Categories: physics.atom-ph
\\
The operation of a BEC based atom interferometer, where the atoms are held in
a weakly-confining magnetic trap and manipulated with counter-propagating laser
beams, is analyzed. A simple analytic model is developed to describe the
dynamics of the interferometer. It is used to find the regions of parameter
space with high and low contrast of the interference fringes for both single
and double reflection interferometers. We demonstrate that for a double
reflection interferometer the coherence time can be increased by shifting the
recombination time. The theory is compared with recent experimental
realizations of these interferometers.
\\ ( http://arxiv.org/abs/0712.2057 , 542kb)
------------------------------------------------------------------------------
\\
arXiv:0712.2070
Date: Thu, 13 Dec 2007 00:30:27 GMT (185kb)

Title: Analytic models of ultra-cold atomic collisions at negative energies and
their application to trap-induced resonances in an optical lattice
Authors: S. G. Bhongale, S. J. J. M. F. Kokkelmans, I. H. Deutsch
Categories: physics.atom-ph
\\
We construct simple analytic models of the $S$-matrix, accounting for both
scattering resonances and smooth background contributions, in order to analyze
the properties of trap-induced-resonances (TIR) occurring in cold collisions of
$^{133}$Cs atoms in separated sites of a polarization-gradient optical lattice.
Such resonances occur at negative energy with respect to the $s$-wave
threshold, and thus cannot be studied easily using direct numerical solutions
of the Schr\"{o}dinger equation. Using our analytic model, we extend previous
studies of negative-energy scattering to the multichannel case which is
relevant to experimental demonstration of the TIR. We find good operating
conditions that should allow for robustness in the presence of
trapping-inhomogeneities while maintaining low probability of inelastic
collisions.
\\ ( http://arxiv.org/abs/0712.2070 , 185kb)
------------------------------------------------------------------------------
\\
arXiv:0712.2089
Date: Thu, 13 Dec 2007 15:39:29 GMT (718kb)

Title: Highly-asymmetric soliton complexes in parabolic optical lattices
Authors: Yaroslav V. Kartashov, Victor V. Vysloukh, Lluis Torner
Categories: physics.optics
Comments: 12 pages, 4 figures, to appear in Optics Letters
\\
We introduce multipole soliton complexes in optical lattices induced by
nondiffracting parabolic beams. Despite the symmetry-breaking dictated by the
curvature of the lattice channels, we find that complex, asymmetric
higher-order states can be stable. The unique topology of parabolic lattices
affords new types of soliton motion: single solitons launched into the lattice
with nonzero transverse momentum perform periodic oscillations along parabolic
paths.
\\ ( http://arxiv.org/abs/0712.2089 , 718kb)
------------------------------------------------------------------------------

The replacements:

------------------------------------------------------------------------------
\\
arXiv:cond-mat/0703585
replaced with revised version Fri, 7 Dec 2007 11:36:37 GMT (24kb)

Title: Temperature Dependence of Critical Number of Particles for Attracting
Atomic Bose Gas
Authors: Shyamal Biswas
Categories: cond-mat.stat-mech
\\ ( http://arxiv.org/abs/cond-mat/0703585 , 24kb)
------------------------------------------------------------------------------
\\
arXiv:0707.1653
replaced with revised version Fri, 7 Dec 2007 12:33:24 GMT (95kb)

Title: Chaos in kicked Bose-Einstein condensates: Bogoliubov resonances
Authors: J. Reslen, C.E. Creffield, and T.S. Monteiro
Categories: quant-ph
\\ ( http://arxiv.org/abs/0707.1653 , 95kb)
------------------------------------------------------------------------------
\\
arXiv:cond-mat/0612496
replaced with revised version Mon, 10 Dec 2007 16:18:02 GMT (25kb)

Title: Superfluid and insulating phases of fermion mixtures in optical lattices
Authors: M. Iskin and C. A. R. Sa de Melo
Categories: cond-mat.supr-con cond-mat.other
Comments: 4 pages with 3 figures (Published version)
Journal-ref: Phys. Rev. Lett. 99, 080403 (2007)
\\ ( http://arxiv.org/abs/cond-mat/0612496 , 25kb)
------------------------------------------------------------------------------
\\
arXiv:0706.2833
replaced with revised version Mon, 10 Dec 2007 20:04:34 GMT (60kb)

Title: Bose-Einstein Condensation in the Relativistic Ideal Bose Gas
Authors: M. Grether, M. de Llano, and George A. Baker Jr
Categories: cond-mat.supr-con
Journal-ref: Phys. Rev. Lett. 99, 200406 (2007)
\\ ( http://arxiv.org/abs/0706.2833 , 60kb)
------------------------------------------------------------------------------
\\
arXiv:0708.3548
replaced with revised version Sat, 8 Dec 2007 07:21:29 GMT (112kb)

Title: One-dimensional fermionic gases with attractive p-wave interaction in a
hard-wall trap
Authors: Yajiang Hao, Yunbo Zhang, Shu Chen
Categories: cond-mat.other cond-mat.str-el
Comments: 6 pages, 5 figures, version published in Phys. Rev. A
Journal-ref: Phys. Rev. A 76, 063601 (2007)
DOI: 10.1103/PhysRevA.76.063601
\\ ( http://arxiv.org/abs/0708.3548 , 112kb)
------------------------------------------------------------------------------
\\
arXiv:0708.3638
replaced with revised version Sun, 9 Dec 2007 18:41:28 GMT (66kb)

Title: Spin dynamics in a one-dimensional ferromagnetic Bose gas
Authors: M. B. Zvonarev, V. V. Cheianov, T. Giamarchi
Categories: cond-mat.other
Comments: Final version as appears in Phys. Rev. Lett.; Eqs. (6) and (14) have
been corrected
\\ ( http://arxiv.org/abs/0708.3638 , 66kb)
------------------------------------------------------------------------------
\\
arXiv:0710.5479
replaced with revised version Sun, 9 Dec 2007 19:41:39 GMT (125kb)

Title: A Weyl function approach to matter-wave coherence and Talbot-Lau effects
Authors: Saijun Wu, Pierre S. Striehl, Mara G. Prentiss
Categories: physics.atom-ph
\\ ( http://arxiv.org/abs/0710.5479 , 125kb)
------------------------------------------------------------------------------
\\
arXiv:cond-mat/0703200
replaced with revised version Tue, 11 Dec 2007 09:06:39 GMT (756kb)

Title: Critical Point of an Interacting Two-Dimensional Atomic Bose Gas
Authors: Peter Kr\"uger (LKB - Lhomond), Zoran Hadzibabic (LKB - Lhomond), Jean
Dalibard (LKB - Lhomond)
Categories: cond-mat.other
Proxy: ccsd hal-00135497
Journal-ref: Physical Review Letters 99 (2007) 040402
\\ ( http://arxiv.org/abs/cond-mat/0703200 , 756kb)
------------------------------------------------------------------------------
\\
arXiv:0707.1538
replaced with revised version Tue, 11 Dec 2007 06:28:45 GMT (11kb)

Title: Transition temperature of the homogeneous and dilute Bose gas in
D-dimensions
Authors: Sang-Hoon Kim
Categories: cond-mat.stat-mech
\\ ( http://arxiv.org/abs/0707.1538 , 11kb)
------------------------------------------------------------------------------
\\
arXiv:0711.2963
replaced with revised version Tue, 11 Dec 2007 16:40:40 GMT (856kb)

Title: Renormalization Group Theory for the Imbalanced Fermi Gas
Authors: K. B. Gubbels and H. T. C. Stoof
Categories: cond-mat.stat-mech cond-mat.supr-con
\\ ( http://arxiv.org/abs/0711.2963 , 856kb)
------------------------------------------------------------------------------
\\
arXiv:cond-mat/0609711
replaced with revised version Wed, 12 Dec 2007 09:15:04 GMT (23kb)

Title: On the theory of superfluidity
Authors: Yongle Yu
Categories: cond-mat.stat-mech
\\ ( http://arxiv.org/abs/cond-mat/0609711 , 23kb)
------------------------------------------------------------------------------
\\
arXiv:0707.2715
replaced with revised version Wed, 12 Dec 2007 11:48:40 GMT (303kb)

Title: Condensation of Ideal Bose Gas Confined in a Box Within a Canonical
Ensemble
Authors: Konstantin Glaum, Hagen Kleinert, Axel Pelster
Categories: cond-mat.stat-mech
Journal-ref: Physical Review A 76, 063604 (2007)
\\ ( http://arxiv.org/abs/0707.2715 , 303kb)
------------------------------------------------------------------------------
\\
arXiv:0712.1251
replaced with revised version Wed, 12 Dec 2007 00:00:52 GMT (320kb)

Title: Quantum Phase Transition between (Luttinger) Liquid and Gas of Cold
Molecules
Authors: K. T. Law and D. E. Feldman
Categories: cond-mat.other cond-mat.str-el
\\ ( http://arxiv.org/abs/0712.1251 , 320kb)
------------------------------------------------------------------------------
\\
arXiv:0707.4392
replaced with revised version Thu, 13 Dec 2007 03:26:30 GMT (23kb)

Title: Effective low-dimensional Hamiltonian for strongly interacting atoms in
a transverse trap
Authors: J. P. Kestner, L.-M. Duan
Categories: cond-mat.other
Comments: v2: 5 pages, 1 figure; expanded presentation of the formalism
Journal-ref: Phys. Rev. A 76, 063610 (2007)
DOI: 10.1103/PhysRevA.76.063610
\\ ( http://arxiv.org/abs/0707.4392 , 23kb)
------------------------------------------------------------------------------

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/
=========================================================================
Matt's arXiv selection: weekly summary of cold-atom papers from arXiv.org
http://www.physics.uq.edu.au/people/mdavis/matts_arXiv/
=========================================================================
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Received on Thu Jan 03 2008 - 11:09:20 EST

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