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

Date: Thu, 24 Apr 2008 22:11:06 +1000

Date: Thu, 24 Apr 2008 22:11:06 +1000

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

Just when you were wondering what had happened to your weekly arXiv email, it's

back! I took a weeks holiday last week and the lead up to being away and the

subsequent catching up has lead to the delay.

This week there are 27 new preprints and 18 replacements.

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arXiv:0804.0625

Date: Thu, 3 Apr 2008 21:20:17 GMT (48kb)

Title: Topological order from quantum loops and nets

Authors: Paul Fendley

Categories: cond-mat.stat-mech cond-mat.str-el

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

\\

I define models of quantum loops and nets which have ground states with

topological order. These make possible excited states comprised of deconfined

anyons with non-abelian braiding. With the appropriate inner product, these

quantum loop models are equivalent to net models whose topological weight

involves the chromatic polynomial. A useful consequence is that the models have

a quantum self-duality, making it possible to find a simple Hamiltonian

preserving the topological order. For the square lattice, this Hamiltonian has

only four-spin interactions.

\\ ( http://arxiv.org/abs/0804.0625 , 48kb)

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arXiv:0804.0782

Date: Fri, 4 Apr 2008 16:42:06 GMT (82kb)

Title: Collective modes in asymmetric ultracold Fermi systems

Authors: Elena Gubankova, Massimo Mannarelli and Rishi Sharma

Categories: cond-mat.supr-con cond-mat.stat-mech

Comments: 22 pages, 7 figures

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

\\

We derive the low energy effective action for the collective modes in systems

of fermions interacting via a short-range s-wave attraction, featuring unequal

chemical potentials for the two fermionic species (asymmetric systems). As a

consequence of the attractive interaction, fermions form a condensate that

spontaneously breaks the U(1) symmetry associated with total number

conservation. Therefore at sufficiently small temperatures and asymmetries, the

system is a superfluid. We obtain criteria of stability for the system from the

coefficients of the low energy effective Lagrangian of the modes describing

fluctuations in the magnitude (Higgs mode) and in the phase (Goldstone mode) of

the difermion condensate. We find that there is a region in parameter space

where the system features one gapless Fermi surface, and is stable. Regions

with two gapless Fermi surfaces are excluded. In the stable gapless region, for

certain values of parameters, the Higgs mode is light. Its mass decreases with

increasing mismatch between the chemical potentials of the two populations, if

we keep the scattering length and the gap parameter constant. Furthermore, we

find that the elasticity of the Higgs mode diverges at the boundary of the

gapless region and these two features may lead to experimentally detectable

effects. As an example, we argue that if the superfluid is put in rotation, the

square of the radius of the outer core is proportional to the ratio of the

Higgs elasticity and the Higgs mass. Therefore one should detect an increase in

the radius of the vortex on increasing the asymmetry, when we pass through the

relevant region in the gapless superfluid phase. Finally, by gauging the global

U(1) symmetry, we relate the coefficients of the effective Lagrangian of the

Goldstone mode with the screening masses of the gauge field.

\\ ( http://arxiv.org/abs/0804.0782 , 82kb)

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arXiv:0804.0254

Date: Tue, 1 Apr 2008 21:45:43 GMT (733kb)

Title: Quantum State Engineering and Precision Metrology using

State-Insensitive Light Traps

Authors: Jun Ye, H. J. Kimble, and Hidetoshi Katori

Categories: quant-ph physics.atom-ph

Comments: 23 pages of main text, 4 figures, and 12 pages of Supporting Online

Material (SOM)

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

\\

Precision metrology and quantum measurement often demand matter be prepared

in well defined quantum states for both internal and external degrees of

freedom. Laser-cooled neutral atoms localized in a deeply confining optical

potential satisfy this requirement. With an appropriate choice of wavelength

and polarization for the optical trap, two electronic states of an atom can

experience the same trapping potential, permitting coherent control of

electronic transitions independent of the atomic center-of-mass motion. We

review a number of recent experiments that use this approach to investigate

precision quantum metrology for optical atomic clocks and coherent control of

optical interactions of single atoms and photons within the context of cavity

quantum electrodynamics. We also provide a brief survey of promising prospects

for future work.

\\ ( http://arxiv.org/abs/0804.0254 , 733kb)

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arXiv:0804.0878

Date: Mon, 7 Apr 2008 13:25:27 GMT (33kb)

Title: Particle partitioning entanglement in itinerant many-particle systems

Authors: O.S. Zozulya, Masudul Haque, K. Schoutens

Categories: cond-mat.other cond-mat.str-el

Comments: 4 pages, 4 figures

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

\\

For itinerant fermionic and bosonic systems, we study `particle

entanglement', defined as the entanglement between two subsets of particles

making up the system. We formulate the general structure of particle

entanglement in many-fermion ground states, analogous to the `area law' for the

more usually studied entanglement between spatial regions. Basic properties of

particle entanglement are uncovered by considering relatively simple itinerant

models.

\\ ( http://arxiv.org/abs/0804.0878 , 33kb)

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arXiv:0804.0971

Date: Mon, 7 Apr 2008 06:43:00 GMT (46kb)

Title: Fast rotating condensates in an asymmetric harmonic trap

Authors: Amandine Aftalion (LJLL), Xavier Blanc (LJLL), Nicolas Lerner (IMJ)

Categories: cond-mat.other

Comments: 4 pages, 2 figures

Proxy: ccsd hal-00270540

\\

We investigate the effect of the anisotropy of a harmonic trap on the

behaviour of a fast rotating Bose-Einstein condensate. Fast rotation is reached

when the rotational velocity is close to the smallest trapping frequency,

thereby deconfining the condensate in the corresponding direction. A striking

new feature is the non-existence of visible vortices for the ground state. The

condensate can be described with the lowest Landau level set of states, but

using distorted complex coordinates. We find that the coarse grained atomic

density behaves like an inverted parabola with large radius in the deconfined

direction, and like a fixed Gaussian in the other direction. It has no visible

vortices, but invisible vortices which are needed to recover the mixed

Thomas-Fermi Gaussian profile. There is a regime of small anisotropy and

intermediate rotational velocity where the behaviour is similar to the

isotropic case: a hexagonal Abrikosov lattice of vortices, with an inverted

parabola profile.

\\ ( http://arxiv.org/abs/0804.0971 , 46kb)

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arXiv:0804.1035

Date: Mon, 7 Apr 2008 14:17:16 GMT (30kb)

Title: Vortex core states in superfluid Fermi-Fermi mixtures with unequal

masses

Authors: M. Iskin

Categories: cond-mat.supr-con cond-mat.other

Comments: 4+ pages with 3 figures, to be submitted to PRA

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

\\

We analyze the vortex core states of two-species (mass imbalanced) superfluid

fermion mixtures as a function of the two-body binding energy in two

dimensions. In particular, we solve the self-consistent Bogoliubov-de Gennes

equations for a population balanced but mass imbalanced mixture of $^{6}$Li and

$^{40}$K atoms at zero temperature. We find that the vortex core is mostly

filled with the light-mass ($^{6}$Li) fermions and that the core density of

heavy-mass ($^{40}$K) fermions is highly depleted. This is in contrast with the

one-species (mass balanced) mixtures, where equal amount of density depletion

is found at the vortex core for both pseudo-spin components.

\\ ( http://arxiv.org/abs/0804.1035 , 30kb)

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arXiv:0804.0906

Date: Sun, 6 Apr 2008 12:49:37 GMT (285kb)

Title: Controlling transition probability from matter-wave soliton to chaos

Authors: Qianquan Zhu, Wenhua Hai, Shiguang Rong

Categories: quant-ph

Comments: 4 pages, 2 figures

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

\\

For a Bose-Einstein condensate loaded into a weak traveling optical

superlattice it is demonstrated that under a stochastic initial set and in a

given parameter region the solitonic chaos appears with a certain probability.

Effects of the lattice depths and wave vectors on the chaos probability are

investigated analytically and numerically, and different chaotic regions

associated with different chaos probabilities are found. The results suggest a

feasible method for eliminating or strengthening chaos by modulating the moving

superlattice experimentally.

\\ ( http://arxiv.org/abs/0804.0906 , 285kb)

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arXiv:0804.0877

Date: Sat, 5 Apr 2008 23:19:38 GMT (8kb)

Title: Mathematical Models in Physics : a Quest for Clarity

Authors: Elemer E. Rosinger

Categories: physics.gen-ph

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

\\

The role of mathematical models in physics has for longer been well

established. The issue of their proper building and use appears to be less

clear. Examples in this regard from relativity and quantum mechanics are

mentioned. Comments concerning a more appropriate way in setting up and using

mathematical models in physics are presented.

\\ ( http://arxiv.org/abs/0804.0877 , 8kb)

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arXiv:0804.1144

Date: Mon, 7 Apr 2008 20:52:44 GMT (787kb)

Title: Signatures of Strong Correlations in One-Dimensional Ultra-Cold Atomic

Fermi Gases

Authors: Paata Kakashvili, S. G. Bhongale, Han Pu and C. J. Bolech

Categories: cond-mat.other cond-mat.str-el

Comments: 4 pages, 2 figures

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

\\

Recent success in manipulating ultra-cold atomic systems allows to probe

different strongly correlated regimes in one-dimension. Regimes such as the

(spin-coherent) Luttinger liquid and the spin-incoherent Luttinger liquid can

be realized by tuning the inter-atomic interaction strength and trap

parameters. We identify the noise correlations of density fluctuations as a

robust observable (uniquely suitable in the context of trapped atomic gases) to

discriminate between these two regimes. Finally, we address the prospects to

realize and probe these phenomena experimentally using optical lattices.

\\ ( http://arxiv.org/abs/0804.1144 , 787kb)

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arXiv:0804.1220

Date: Tue, 8 Apr 2008 09:15:16 GMT (4kb)

Title: The model charged spinless nonideal Bose gas within finite temperatures

Authors: V. N. Minasyan

Categories: cond-mat.supr-con

Comments: 8 pages

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

\\

First, it is demonstrated an exactly solution of the model of charged

nonideal Bose gas, at quantity of the condensate fraction

$0\leq\frac{N_0}{N}\leq 1$. As new result of presented theory is that an

application of the S-wave scattering between charged bosons, in addition to a

repulsive Coulomb interaction, leads to a creation of phonon term in the energy

spectrum of plasmon excitations. As new result of presented theory, there are

absent the phonons and plasmon gap, at critical temperature $T_c$.

\\ ( http://arxiv.org/abs/0804.1220 , 4kb)

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arXiv:0804.1277

Date: Tue, 8 Apr 2008 13:57:00 GMT (8kb)

Title: Hydrodynamics of Bose and Fermi superfluids at zero temperature: the

superfluid nonlinear Schodinger equation

Authors: Luca Salasnich (CNR-INFM and CNISM, University of Padua)

Categories: cond-mat.stat-mech cond-mat.other

Comments: 4 pages, no figures, prepared for the Special Issue of Laser Physics:

Physics of Cold Trapped Atoms

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

\\

We discuss the zero-temperature hydrodynamics equations of bosonic and

fermionic superfluids and their connection with generalized Gross-Pitaevskii

and Ginzburg-Landau equations through a single superfluid nonlinear Schrodinger

equation.

\\ ( http://arxiv.org/abs/0804.1277 , 8kb)

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arXiv:0804.1203

Date: Tue, 8 Apr 2008 07:50:47 GMT (90kb)

Title: Quantum improvement of time transfer between remote clocks

Authors: Brahim Lamine (LKB - Jussieu), Claude Fabre (LKB - Jussieu), Nicolas

Treps (LKB - Jussieu)

Categories: quant-ph

Proxy: ccsd hal-00270912

\\

Exchanging light pulses to perform accurate space-time positioning is a

paradigmatic issue of physics. It is ultimately limited by the quantum nature

of light, which introduces fluctuations in the optical measurements and leads

to the so-called Standard Quantum Limit (SQL). We propose a new scheme

combining homodyne detection and mode-locked femtosecond lasers that lead to a

new SQL in time transfer, potentially reaching the yoctosecond range

(10^-21-10^-24 s). We prove that no other measurement strategy can lead to

better sensitivity with shot noise limited light. We then demonstrate that this

already very low SQL can be overcome using appropriately multimode squeezed

light. Benefitting from the large number of photons used in the experiment and

from the optimal choice of both the detection strategy and of the quantum

resource, the proposed scheme represents a significant potential improvement in

space-time positioning.

\\ ( http://arxiv.org/abs/0804.1203 , 90kb)

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arXiv:0804.1162

Date: Tue, 8 Apr 2008 00:22:14 GMT (248kb)

Title: Gaussian Schell Source as Model for Slit-Collimated Atomic and Molecular

Beams

Authors: Ben McMorran, Alex Cronin

Categories: physics.optics physics.atom-ph

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

\\

We show how to make a Gaussian Schell-model (GSM) beam. Then we compare the

intensity profile, the transverse coherence width and the divergence angle of a

GSM beam with those same properties of a beam that is collimated with two

hard-edged slits. This work offers an intuitive way to understand various

interferometer designs, and we compare our results with data.

\\ ( http://arxiv.org/abs/0804.1162 , 248kb)

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arXiv:0804.1376

Date: Tue, 8 Apr 2008 22:09:15 GMT (17kb)

Title: Construction of density operator for a general mean-field Hamiltonian

and its application to the models of correlated fermions

Authors: Jakub J\c{e}drak, Jozef Spa{\l}ek

Categories: cond-mat.str-el cond-mat.stat-mech

Comments: 17 pages

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

\\

We analyze a class of the mean-field lattice-fermion Hamiltonians. We

construct the corresponding grand-canonical density operator for such a model

system. New terms are introduced, and may be interpreted as local fugacities,

molecular fields, etc. The presence of such terms is an unavoidable consequence

of the consistent statistical description. Although in some cases (e.g. the

Hartree or the Hartree-Fock type of approximations) the presented formalism is

redundant, in general (e.g. for a renormalized t-J model) it leads to

nontrivial modifications. The case of zero temperature is also briefly

analyzed.

\\ ( http://arxiv.org/abs/0804.1376 , 17kb)

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arXiv:0804.1429

Date: Wed, 9 Apr 2008 16:57:38 GMT (119kb)

Title: Temperature and final state effects in radio frequency spectroscopy

experiments on atomic Fermi gases

Authors: Yan He, Chih-Chun Chien, Qijin Chen, and K. Levin

Categories: cond-mat.supr-con cond-mat.str-el

Comments: 4 pages, 4 figures

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

\\

We present a formalism for addressing radio frequency (RF) spectroscopy

experiments in homogeneous atomic Fermi gases in the presence of pairing, but

not necessarily superfluidity, and at finite temperatures, $T$. Our approach

includes final state effects and our calculated spectra satisfy the zeroth- and

first-moment sum rules at all $T$. We show how the continuum and bound state

contributions depend significantly on $T$, and explain recent RF experiments on

"bound-bound" transitions. We make predictions for future experiments.

\\ ( http://arxiv.org/abs/0804.1429 , 119kb)

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arXiv:0804.1459

Date: Wed, 9 Apr 2008 11:21:48 GMT (424kb)

Title: Quantum Phase Transition Induced by a Preformed Pair in a Boson-Fermion

Model of Fulleride Superconductivity

Authors: Richard H. Squire, Norman H. March

Categories: cond-mat.supr-con cond-mat.str-el

Comments: presented at Sanibel Symposium, Feb 2008

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

\\

There continues to be enormous interest in the BCS to BEC transition as there

still is no exact theory. We recently reported a revealing reinterpretation of

the condensed phase Boson-Fermion Model (BFM) by comparing it to a cold atom

formulation [1]. While the ground and singly excited states appear to remain

continuous in all models we have examined, the collective modes contain a

singularity due to a Feshbach resonance (tuned by doping) causing a breakdown

of the Migdal theorem. As a result of vertex corrections, there is a

fundamental change in the nature of the superconductivity due to the formation

of preformed pairs as the previously suggested location [1] of a quantum

critical point in the fulleride phase diagram is passed. The result is a

quantum phase transition (QPT) between BCS and BEC-like (or Feshbach resonance)

superconductivity (SC).

We discuss features of the resonance and the role of the experimentally

observed preformed pair formation in fullerides, essential to the Boson-Fermion

Model (BFM), and often speculated since the work of Nozieres and Schmitt-Rink

[17]. Here, we present arguments to establish a model of the preformed pair

which can be favorably compared to a circular charge density wave (CDW)

isolated on a fulleride molecule. The binding is much larger than a Cooper

pair. The CDW seems to be stabalized by splitting of the Jahn-Teller active

vibrational modes to reduce Coulomb repulsions. Our conclusions are: 1) the

doping of two electrons into triply degenerate orbitals results in the

experimentally observed singlet state (CDW); and 2) this CDW (preformed pair)

has a dual role as doping is varied: suppression of BCS SC and enabling a

Feshbach resonance form of SC.

\\ ( http://arxiv.org/abs/0804.1459 , 424kb)

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arXiv:0804.1474

Date: Wed, 9 Apr 2008 13:23:58 GMT (62kb)

Title: Properties of Fractional Exclusion Statistics in Interacting Particle

Systems

Authors: Drago\c{s}-Victor Anghel

Categories: cond-mat.stat-mech cond-mat.other

Comments: 8 pages, 3 figures, to appear in Rom. J. Phys. Is a continuation of

J. Phys. A: Math. Theor. 40 F1013-F1019 (2007); arXiv:0710.0724, and

arXiv:0710.0728

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

\\

We show that fractional exclusion statistics is manifested in general in

interacting systems and we discuss the conjecture recently introduced (J. Phys.

A: Math. Theor. 40, F1013, 2007), according to which if in a thermodynamic

system the mutual exclusion statistics parameters are not zero, then they have

to be proportional to the dimension of the Hilbert space on which they act. By

using simple, intuitive arguments, but also concrete calculations in

interacting systems models, we show that this conjecture is not some abstract

consequence of unphysical modeling, but is a natural--and for a long time

overlooked--property of fractional exclusion statistics. We show also that the

fractional exclusion statistics is the consequence of interaction between the

particles of the system and it is due to the change from the description of the

system in terms of free-particle energies, to the description in terms of the

quasi-particle energies. From this result, the thermodynamic equivalence of

systems of the same, constant density of states, but any exclusion statistics

follows immediately.

\\ ( http://arxiv.org/abs/0804.1474 , 62kb)

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arXiv:0804.1514

Date: Wed, 9 Apr 2008 15:55:21 GMT (113kb,D)

Title: Time-dependent current-density-functional theory of spin-charge

separation and spin drag in one-dimensional ultracold Fermi gases

Authors: Gao Xianlong, Marco Polini, Diego Rainis, M.P. Tosi, G. Vignale

Categories: cond-mat.str-el

Comments: 4+epsilon pages, 3 figures, submitted. High-quality figures can be

requested to the authors

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

\\

Motivated by the large interest in the non-equilibrium dynamics of

low-dimensional quantum many-body systems, we present a fully-microscopic

theoretical and numerical study of the "charge" and "spin" dynamics in a

one-dimensional ultracold Fermi gas following a quench. Our approach, which is

based on time-dependent current-density-functional theory, is applicable well

beyond the linear-response regime and produces both spin-charge separation and

spin-drag-induced broadening of the spin packets.

\\ ( http://arxiv.org/abs/0804.1514 , 113kb)

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arXiv:0804.1377

Date: Tue, 8 Apr 2008 22:12:17 GMT (85kb)

Title: Quantum Noise as an Entanglement Meter

Authors: Israel Klich, Leonid Levitov

Categories: quant-ph

License: http://creativecommons.org/licenses/by-nc-sa/3.0/

\\

Entanglement entropy, which is a measure of quantum correlations between

separate parts of a many-body system, has emerged recently as a fundamental

quantity in broad areas of theoretical physics, from cosmology and field theory

to condensed matter theory and quantum information. The universal appeal of the

entanglement entropy concept is related, in part, to the fact that it is

defined solely in terms of the many-body density matrix of the system, with no

relation to any particular observables. However, for the same reason, it has

not been clear how to access this quantity experimentally. Here we derive a

universal relation between entanglement entropy and the fluctuations of current

flowing through a quantum point contact (QPC) which opens a way to perform a

direct measurement of entanglement entropy. In particular, by utilizing

space-time duality of 1d systems, we relate electric noise generated by opening

and closing the QPC periodically in time with the seminal S = 1/3 log L

prediction of conformal field theory.

\\ ( http://arxiv.org/abs/0804.1377 , 85kb)

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arXiv:0804.1453

Date: Wed, 9 Apr 2008 10:35:03 GMT (141kb)

Title: Macroscopic Quantum Superposition and Entanglement in light reflection

from Bose-Einstein Condensates

Authors: Francesco S. Cataliotti and Francesco De Martini

Categories: quant-ph

Comments: 4 pages, 4 figures

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

\\

The multiphoton quantum superposition generated by a quantum-injected optical

parametric amplifier (QI-OPA) seeded by a single-photon belonging to an EPR

entangled pair is made to interact with a Mirror-BEC shaped as a Bragg

interference structure. The effect can be greatly enhanced if the mirror is

part of a cavity structure or is used within an optical interferometer. The

overall process will realize an Entangled Macroscopic Quantum Superposition

involving a ''microscopic'' singe-photon state of polarization and the coherent

''macroscopic'' displacement of the BEC structure acting in space-like

separated distant places.

\\ ( http://arxiv.org/abs/0804.1453 , 141kb)

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arXiv:0804.1367

Date: Wed, 9 Apr 2008 18:57:02 GMT (63kb)

Title: Influence of the Radio-Frequency source properties on RF-based atom

traps

Authors: Olivier Morizot (LPL), Laurent Longchambon (LPL), Raghavan Kollengode

Easwaran (LPL), Romain Dubessy (LPL), Elena Knyazchyan (LPL), Paul-Eric

Pottie (LPL), Vincent Lorent (LPL), H\'el\`ene Perrin (LPL)

Categories: physics.atom-ph

Comments: 5 figures, 7 pages

Proxy: ccsd hal-00271653

Journal-ref: The European Physical Journal D 47 (2008) 209

DOI: 10.1140/epjd/e2008-00050-2

\\

We discuss the quality required for the RF source used to trap neutral atoms

in RF-dressed potentials. We illustrate this discussion with experimental

results obtained on a Bose-Einstein condensation experiment with different RF

sources.

\\ ( http://arxiv.org/abs/0804.1367 , 63kb)

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arXiv:0804.1144 (*cross-listing*)

Date: Mon, 7 Apr 2008 20:52:44 GMT (787kb)

Title: Signatures of Strong Correlations in One-Dimensional Ultra-Cold Atomic

Fermi Gases

Authors: Paata Kakashvili, S. G. Bhongale, Han Pu and C. J. Bolech

Categories: cond-mat.other cond-mat.str-el physics.atom-ph

Comments: 4 pages, 2 figures

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

\\

Recent success in manipulating ultra-cold atomic systems allows to probe

different strongly correlated regimes in one-dimension. Regimes such as the

(spin-coherent) Luttinger liquid and the spin-incoherent Luttinger liquid can

be realized by tuning the inter-atomic interaction strength and trap

parameters. We identify the noise correlations of density fluctuations as a

robust observable (uniquely suitable in the context of trapped atomic gases) to

discriminate between these two regimes. Finally, we address the prospects to

realize and probe these phenomena experimentally using optical lattices.

\\ ( http://arxiv.org/abs/0804.1144 , 787kb)

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arXiv:0804.1547

Date: Wed, 9 Apr 2008 20:00:26 GMT (612kb)

Title: Supersolid state of ultracold fermions in an optical lattice

Authors: Akihisa Koga, Takuji Higashiyama, Kensuke Inaba, Seiichiro Suga, and

Norio Kawakami

Categories: cond-mat.supr-con

Comments: 4 pages, 4 figures

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

\\

We study ultracold fermionic atoms trapped in an optical lattice with

harmonic confinement by means of the dynamical mean-field approximation. It is

demonstrated that a supersolid state, where an s-wave superfluid coexists with

a density-wave state with a checkerboard pattern, is stabilized by attractive

onsite interactions on a square lattice. Our new finding here is that a

confining potential plays an invaluable role in stabilizing the supersolid

state. We establish a rich phase diagram at low temperatures, which clearly

shows how the insulator, the density wave and the superfluid compete with each

other to produce an intriguing domain structure. Our results shed light on the

possibility of the supersolid state in fermionic optical lattice systems.

\\ ( http://arxiv.org/abs/0804.1547 , 612kb)

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arXiv:0804.1621

Date: Thu, 10 Apr 2008 12:17:06 GMT (477kb)

Title: Direct observation of Anderson localization of matter-waves in a

controlled disorder

Authors: Juliette Billy (LCFIO), Vincent Josse (LCFIO), Zhanchun Zuo (LCFIO),

Alain Bernard (LCFIO), Ben Hambrecht (LCFIO), Pierre Lugan (LCFIO), David

Cl\'ement (LCFIO), Laurent Sanchez-Palencia (LCFIO), Philippe Bouyer (LCFIO),

Alain Aspect (LCFIO)

Categories: cond-mat.dis-nn cond-mat.other

Proxy: ccsd hal-00271681

\\

We report the observation of exponential localization of a Bose-Einstein

condensate (BEC) released into a one-dimensional waveguide in the presence of a

controlled disorder created by laser speckle . We operate in a regime allowing

AL: i) weak disorder such that localization results from many quantum

reflections of small amplitude; ii) atomic density small enough that

interactions are negligible. We image directly the atomic density profiles vs

time, and find that weak disorder can lead to the stopping of the expansion and

to the formation of a stationary exponentially localized wave function, a

direct signature of AL. Fitting the exponential wings, we extract the

localization length, and compare it to theoretical calculations. Moreover we

show that, in our one-dimensional speckle potentials whose noise spectrum has a

high spatial frequency cut-off, exponential localization occurs only when the

de Broglie wavelengths of the atoms in the expanding BEC are larger than an

effective mobility edge corresponding to that cut-off. In the opposite case, we

find that the density profiles decay algebraically, as predicted in [Phys. Rev.

Lett. 98, 210401 (2007)]. The method presented here can be extended to

localization of atomic quantum gases in higher dimensions, and with controlled

interactions.

\\ ( http://arxiv.org/abs/0804.1621 , 477kb)

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arXiv:0804.1672

Date: Thu, 10 Apr 2008 12:23:03 GMT (54kb)

Title: Criterion for Bose-Einstein condensation in traps and self-bound systems

Authors: T. Yamada, Y. Funaki, H. Horiuchi, G. Roepke, P. Schuck, and A.

Tohsaki

Categories: cond-mat.other

Comments: 15 pages, 1 figure

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

\\

The internal one-particle density matrix is discussed for Bose-Einstein

condensates with finite number of particles in a harmonic trap. The outcome of

the digonalization of the density matrix depends on the choice of the internal

coordinates: The Pethick-Pitaevskii-type internal density matrix, whose

analytical eigenvalues and eigenfunctions are evaluated, yields a fragmented

condensate, while the Jacobi-type internal density matrix leads to an ideal

condensate. We give a criterion for the choice of the internal coordinates: In

the macroscopic limit the internal density matrix should have eigenvalues and

eigenfunctions of an ideal Bose-Einstein condensate, this being a very physical

condition for cases where the system is also an ideal Bose condensation in the

laboratory frame. One choice fulfilling this boundary condition is given by the

internal Jacobi coordinates, while the internal coordinates with respect to the

center of mass do not satisfy the condition. Based on our criterion, a general

definition of the internal one-particle density matrix is presented in a

self-bound system, consisting of interacting bosons.

\\ ( http://arxiv.org/abs/0804.1672 , 54kb)

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\\

arXiv:0804.1691

Date: Thu, 10 Apr 2008 12:51:59 GMT (58kb)

Title: Statistical correlations of an anyon liquid at low temperatures

Authors: F. M. D. Pellegrino, G. G. N. Angilella, N. H. March, R. Pucci

Categories: cond-mat.stat-mech cond-mat.mes-hall

Comments: to appear in Phys. Chem. Liquids

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

\\

Using a proposed generalization of the pair distribution function for a gas

of non-interacting particles obeying fractional exclusion statistics in

arbitrary dimensionality, we derive the statistical correlations in the

asymptotic limit of vanishing or low temperature. While Friedel-like

oscillations are present in nearly all non-bosonic cases at T=0, they are

characterized by exponential damping at low temperature. We discuss the

dependence of these features on dimensionality and on the value of the

statistical parameter alpha.

\\ ( http://arxiv.org/abs/0804.1691 , 58kb)

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\\

arXiv:0804.1759

Date: Thu, 10 Apr 2008 17:00:32 GMT (220kb)

Title: Trapped Phase-Segregated Bose-Fermi Mixtures and their Collective

Excitations

Authors: Bert Van Schaeybroeck and Achilleas Lazarides

Categories: cond-mat.stat-mech

Comments: 5 pages, 2 figures

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

\\

Recent progress in the field of ultracold gases has allowed the creation of

phase-segregated Bose-Fermi systems. We present a theoretical study of their

collective excitations at zero temperature. Analytically solving the transport

equation for the fully-polarized fermionic phase, we extract the monopole mode

frequencies and their damping rates as a function of the fraction of fermions

in the trap. A criterion for damping to occur, also valid for multipole

excitations, is established. We then use a hydrodynamic approximation for the

fermions to obtain further results concerning in-phase and out-of-phase motions

of the bosonic core and the surrounding fermionic shell.

\\ ( http://arxiv.org/abs/0804.1759 , 220kb)

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The replacements:

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arXiv:0704.0480

replaced with revised version Fri, 4 Apr 2008 01:45:29 GMT (0kb,I)

Title: Enhanced quantum Zeno effect and bunching in the decay of interacting

bosons from an unstable state

Authors: Sungyun Kim, Artem Dudarev and Joachim Brand

Categories: cond-mat.mes-hall

Comments: paper withdrawn by author

\\ ( http://arxiv.org/abs/0704.0480 , 0kb)

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\\

arXiv:0709.0499

replaced with revised version Thu, 3 Apr 2008 22:00:34 GMT (116kb)

Title: Scattering Models for Ultracold Atoms

Authors: Eric Braaten, Masaoki Kusunoki and Dongqing Zhang

Categories: cond-mat.other hep-ph nucl-th

Comments: 60 pages, 6 figures, minor corrections

\\ ( http://arxiv.org/abs/0709.0499 , 116kb)

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\\

arXiv:0801.2078

replaced with revised version Fri, 4 Apr 2008 16:44:01 GMT (11kb)

Title: On entropy growth and the hardness of simulating time evolution

Authors: Norbert Schuch, Michael M. Wolf, Karl Gerd H. Vollbrecht, J. Ignacio

Cirac

Categories: quant-ph cond-mat.str-el

Comments: 15 pages. v2: Published version, Journal-Ref. added

Journal-ref: New J. Phys. 10, 033032 (2008)

\\ ( http://arxiv.org/abs/0801.2078 , 11kb)

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\\

arXiv:0801.3137

replaced with revised version Fri, 4 Apr 2008 05:44:12 GMT (11kb)

Title: Condition for emergence of complex eigenvalues in the Bogoliubov-de

Gennes equations

Authors: Y.Nakamura, M.Mine, M.Okumura, and Y.Yamanaka

Categories: cond-mat.other

Comments: 7pages

Journal-ref: Phys. Rev. A 77, 043601 (2008)

DOI: 10.1103/PhysRevA.77.043601

\\ ( http://arxiv.org/abs/0801.3137 , 11kb)

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\\

arXiv:0801.3307

replaced with revised version Fri, 4 Apr 2008 07:52:21 GMT (188kb)

Title: Solitons in two-dimensional Bose-Einstein condensates

Authors: Shunji Tsuchiya, Franco Dalfovo, Lev P. Pitaevskii

Categories: cond-mat.supr-con cond-mat.other

Comments: 4 pages, 4 figures, published version

Journal-ref: Phys. Rev. A 77, 045601 (2008)

\\ ( http://arxiv.org/abs/0801.3307 , 188kb)

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\\

arXiv:0802.0728

replaced with revised version Fri, 4 Apr 2008 07:05:27 GMT (151kb)

Title: Anomalous Enhancement of Quasi-particle Current near a Potential Barrier

in a BEC

Authors: S. Tsuchiya, Y. Ohashi

Categories: cond-mat.other cond-mat.supr-con

Comments: 4 pages, 3 figures, revised version

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

\\ ( http://arxiv.org/abs/0802.0728 , 151kb)

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\\

arXiv:0802.3774

replaced with revised version Fri, 4 Apr 2008 19:15:47 GMT (881kb)

Title: The quasi-periodic Bose-Hubbard model and localization in

one-dimensional cold atomic gases

Authors: G. Roux, T. Barthel, I. P. McCulloch, C. Kollath, U. Schollwoeck, T.

Giamarchi

Categories: cond-mat.str-el cond-mat.dis-nn

Comments: 17 pages, 19 figures

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

\\ ( http://arxiv.org/abs/0802.3774 , 881kb)

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\\

arXiv:0708.1567

replaced with revised version Fri, 4 Apr 2008 16:27:47 GMT (25kb)

Title: Strings, Projected Entangled Pair States, and variational Monte Carlo

methods

Authors: Norbert Schuch, Michael M. Wolf, Frank Verstraete, J. Ignacio Cirac

Categories: quant-ph cond-mat.str-el

Comments: 4 pages. v2: Submitted version, containing more numerical data.

Changed title and renamed "string states" to "string-bond states" to comply

with PRL conventions. v3: Accepted version, Journal-Ref. added (title differs

from journal)

Journal-ref: Phys. Rev. Lett. 100, 040501 (2008)

\\ ( http://arxiv.org/abs/0708.1567 , 25kb)

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\\

arXiv:cond-mat/0703322

replaced with revised version Sun, 6 Apr 2008 13:32:42 GMT (348kb)

Title: Heteronuclear molecules in an optical lattice: Theory and experiment

Authors: Frank Deuretzbacher, Kim Plassmeier, Daniela Pfannkuche, F\'elix

Werner, Christian Ospelkaus, Silke Ospelkaus, Klaus Sengstock, Kai Bongs

Categories: cond-mat.other physics.atom-ph

Comments: 9 pages, 7 figures, revised discussion of transfer efficiency

Journal-ref: Phys. Rev. A 77, 032726 (2008)

DOI: 10.1103/PhysRevA.77.032726

\\ ( http://arxiv.org/abs/cond-mat/0703322 , 348kb)

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\\

arXiv:0709.2374

replaced with revised version Mon, 7 Apr 2008 12:51:48 GMT (9kb)

Title: Correlations in an expanding gas of hard-core bosons

Authors: D. M. Gangardt, M. Pustilnik

Categories: cond-mat.stat-mech cond-mat.other

\\ ( http://arxiv.org/abs/0709.2374 , 9kb)

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\\

arXiv:0711.0889

replaced with revised version Mon, 7 Apr 2008 18:53:10 GMT (111kb)

Title: Dipolar bosons in a planar array of one-dimensional tubes

Authors: C. Kollath, Julia S. Meyer, T. Giamarchi

Categories: cond-mat.other cond-mat.str-el

Journal-ref: Phys. Rev. Lett. 100, 130403 (2008)

DOI: 10.1103/PhysRevLett.100.130403

\\ ( http://arxiv.org/abs/0711.0889 , 111kb)

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\\

arXiv:0801.3437

replaced with revised version Mon, 7 Apr 2008 09:55:09 GMT (416kb)

Title: Damped Bloch Oscillations of Bose-Einstein Condensates in Disordered

Potential Gradients

Authors: S. Drenkelforth, G. Kleine B\"uning, J. Will, T. Schulte, N. Murray,

W. Ertmer, L. Santos, and J.J. Arlt

Categories: cond-mat.other

Comments: to be published in New Journal of Physics

\\ ( http://arxiv.org/abs/0801.3437 , 416kb)

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\\

arXiv:0802.2101

replaced with revised version Mon, 7 Apr 2008 19:29:32 GMT (42kb)

Title: Stability of Superflow for Ultracold Fermions in Optical Lattices

Authors: A.A. Burkov, Arun Paramekanti

Categories: cond-mat.supr-con cond-mat.str-el

Comments: 4+ pages, 2 figures

\\ ( http://arxiv.org/abs/0802.2101 , 42kb)

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\\

arXiv:0804.0007

replaced with revised version Sun, 6 Apr 2008 21:41:50 GMT (969kb,D)

Title: Stochastic Mean-Field Theory for the Disordered Bose-Hubbard Model

Authors: U. Bissbort, W. Hofstetter

Categories: cond-mat.dis-nn cond-mat.other

Comments: 4 pages, 5 figures

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

\\ ( http://arxiv.org/abs/0804.0007 , 969kb)

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\\

arXiv:0712.1543

replaced with revised version Mon, 7 Apr 2008 08:25:43 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, 5 pages, 1 figure

Journal-ref: Phys. Rev. A 77, 043606 (2008)

DOI: 10.1103/PhysRevA.77.043606

\\ ( http://arxiv.org/abs/0712.1543 , 493kb)

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\\

arXiv:0710.1853

replaced with revised version Tue, 8 Apr 2008 15:50:56 GMT (40kb)

Title: Engineering many-body quantum dynamics by disorder

Authors: Pierfrancesco Buonsante and Sandro Wimberger

Categories: cond-mat.dis-nn cond-mat.stat-mech

Comments: 4 pages, 4 figures (improved version), to be published in PRA

\\ ( http://arxiv.org/abs/0710.1853 , 40kb)

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\\

arXiv:cond-mat/0503757

replaced with revised version Wed, 9 Apr 2008 19:29:08 GMT (7kb)

Title: Casimir Friction II: Casimir effect and drag in zero temperature

superfluids

Authors: D. C. Roberts and Y. Pomeau

Categories: cond-mat.stat-mech

Comments: To appear in Modern Encyclopedia of Mathematical Physics (MEMPhys);

companion article to arXiv:0704.2194; v5 - corrected boundary condition,

other minor editorial changes

\\ ( http://arxiv.org/abs/cond-mat/0503757 , 7kb)

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\\

arXiv:0711.4896

replaced with revised version Wed, 9 Apr 2008 08:34:01 GMT (149kb)

Title: Dephasing and the steady state in quantum many-particle systems

Authors: Thomas Barthel, Ulrich Schollw\"ock

Categories: cond-mat.stat-mech

Comments: 4 pages, 3 figures, minor changes

Journal-ref: Phys. Rev. Lett. 100, 100601 (2008)

DOI: 10.1103/PhysRevLett.100.100601

\\ ( http://arxiv.org/abs/0711.4896 , 149kb)

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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 May 08 2008 - 11:45:46 EST

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