From: Matthew Davis <mdavis_at_physics.uq.edu.au>

Date: Fri, 21 Dec 2007 21:48:29 +1000

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

Comments: 8pages,12figures

\\

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

Comments: 21 pages, 6 figures

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

Comments: 21 pages

\\

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

Comments: 7 pages, 5 figures

\\

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

Comments: 4 pages, 4 figures

\\

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

Comments: 6 pages, 4 figures

\\

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

Comments: 11 pages, 3 figures

\\

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

relevant parameters are made.

\\ ( 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

radiation pressure

Authors: M. Bhattacharya, P.-L. Giscard, and P. Meystre

Categories: quant-ph

Comments: 3 figures

\\

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

Comments: 11 pages, 4 figures

\\

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

Comments: 24 pages, 7 figures

\\

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

adiabatic passage

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

improved conditions of adiabaticity.

\\ ( 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

Comments: 5 pages, 3 figures

\\

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

Comments: 5 pages, 4 figures

\\

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)

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\\

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

Comments: 4 pages, 4 figures

\\

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)

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\\

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

Comments: 10 pages, 4 figures

\\

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)

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\\

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)

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\\

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)

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\\

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

Comments: 25 pages, 6 figures

\\

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)

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\\

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

Comments: 9 pages

\\

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)

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\\

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)

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The replacements:

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\\

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

Comments: 9 pages, 3 figures

\\ ( http://arxiv.org/abs/cond-mat/0703585 , 24kb)

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\\

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

Comments: 5 pages

\\ ( http://arxiv.org/abs/0707.1653 , 95kb)

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\\

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)

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\\

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

Comments: 10 pages, 4 figures

Journal-ref: Phys. Rev. Lett. 99, 200406 (2007)

\\ ( http://arxiv.org/abs/0706.2833 , 60kb)

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\\

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)

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\\

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)

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\\

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

Comments: 38 pages, 17 figures

\\ ( http://arxiv.org/abs/0710.5479 , 125kb)

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\\

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)

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\\

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

Comments: 4 pages, 2 figure

\\ ( http://arxiv.org/abs/0707.1538 , 11kb)

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\\

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

Comments: References added, 4 pages, 2 figures

\\ ( http://arxiv.org/abs/0711.2963 , 856kb)

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\\

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

Comments: simplified version; added references; 6 pages, 6 figures

\\ ( http://arxiv.org/abs/cond-mat/0609711 , 23kb)

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\\

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

Comments: 18 pages, 8 figures

Journal-ref: Physical Review A 76, 063604 (2007)

\\ ( http://arxiv.org/abs/0707.2715 , 303kb)

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\\

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

Comments: 5 pages; 3 figures

\\ ( http://arxiv.org/abs/0712.1251 , 320kb)

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\\

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)

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Till next time,

Matt.

-- ========================================================================= Dr M. J. Davis, Senior Lecturer in Physics School of Physical Sciences, email: mdavis_at_physics.uq.edu.au University of Queensland, ph : +61 7 334 69824 Brisbane, QLD 4072, fax : +61 7 336 51242 Australia. http://www.physics.uq.edu.au/people/mdavis/ ========================================================================= Matt's arXiv selection: weekly summary of cold-atom papers from arXiv.org http://www.physics.uq.edu.au/people/mdavis/matts_arXiv/ ========================================================================= Legal stuff: Unless stated otherwise, this e-mail represents only the views of the sender and not the views of the University of Queensland =========================================================================Received on Thu Jan 03 2008 - 11:09:20 EST

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