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

Date: Fri, 28 Jul 2006 19:48:42 +1000 (EST)

Date: Fri, 28 Jul 2006 19:48:42 +1000 (EST)

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

Hi all,

The arXiv mailings continue to be irregular due to my travels (this week I am at

Orsay). Two interesting looking papers on the formation of heteronuclear

molecules this week, one from Hamburg and one from Boulder.

Home page: http://www.physics.uq.edu.au/people/mdavis/matts_arXiv/

The abstracts:

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Paper: cond-mat/0607569

Date: Fri, 21 Jul 2006 20:21:58 GMT (97kb)

Title: Nonuniform mixed-parity superfluid state in Fermi gases

Authors: K. V. Samokhin and M. S. Mar'enko

Comments: 4 pages, 1 figure

Subj-class: Superconductivity

\\

We study the effects of dipole interaction on the superfluidity in a

homogeneous Fermi gas with population imbalance. We show that the

Larkin-Ovchinnikov-Fulde-Ferrell phase is replaced by another nonuniform

superfluid phase, in which the order parameter has a nonzero triplet component

induced by the dipole interaction.

\\ ( http://arXiv.org/abs/cond-mat/0607569 , 97kb)

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Paper: cond-mat/0607581

Date: Sun, 23 Jul 2006 01:18:57 GMT (261kb)

Title: Ultracold heteronuclear molecules in a 3D optical lattice

Authors: C. Ospelkaus, S. Ospelkaus, L. Humbert, P. Ernst, K. Sengstock, and K.

Bongs

Comments: 4 pages, 4 figures

Subj-class: Statistical Mechanics

\\

We report on the creation of ultracold heteronuclear molecules assembled from

fermionic 40K and bosonic 87Rb atoms in a 3D optical lattice. Molecules are

produced at a heteronuclear Feshbach resonance both on the attractive and the

repulsive side of the resonance. We precisely determine the binding energy of

the heteronuclear molecules from rf spectroscopy across the Feshbach resonance.

We characterize the lifetime of the molecular sample as a function of magnetic

field and measure between 20 and 120ms. The efficiency of molecule creation via

rf association is measured and is found to decrease as expected for more deeply

bound molecules.

\\ ( http://arXiv.org/abs/cond-mat/0607581 , 261kb)

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Paper: cond-mat/0607600

Date: Mon, 24 Jul 2006 16:06:57 GMT (34kb)

Title: Analytic, Group-Theoretic Density Profiles for Confined, Correlated

N-Body Systems

Authors: W.B. Laing, M. Dunn, D.K. Watson

Comments: 15 pages, 2 figures, submitted to Physics Review A

Subj-class: Other

\\

Confined quantum systems involving $N$ identical interacting particles are to

be found in many areas of physics, including condensed matter, atomic and

chemical physics. A beyond-mean-field perturbation method that is applicable,

in principle, to weakly, intermediate, and strongly-interacting systems has

been set forth by the authors in a previous series of papers. Dimensional

perturbation theory was used, and in conjunction with group theory, an analytic

beyond-mean-field correlated wave function at lowest order for a system under

spherical confinement with a general two-body interaction was derived. In the

present paper, we use this analytic wave function to derive the corresponding

lowest-order, analytic density profile and apply it to the example of a

Bose-Einstein condensate.

\\ ( http://arXiv.org/abs/cond-mat/0607600 , 34kb)

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Paper: cond-mat/0607618

Date: Mon, 24 Jul 2006 15:58:15 GMT (62kb)

Title: Single-particle versus pair condensation of hard-core bosons with

correlated hopping

Authors: K.P. Schmidt, J. Dorier, A. Laeuchli, and F. Mila

Comments: 8 pages, 7 figures

Subj-class: Other

\\

We investigate the consequences of correlated hopping on the ground state

properties of hard-core bosons on a square lattice as revealed by extensive

exact diagonalizations and quantum Monte Carlo simulations. While for non

interacting hard-core bosons the effective attraction induced by the correlated

hopping leads to phase separation at low density, we show that a modest

nearest-neighbor repulsion suppresses phase separation, leading to a remarkable

low-density pairing phase with no single particle Bose-Einstein condensation

but long-range two-particle correlations, signaling a condensation of pairs. We

also explain why the unusual properties of the pairing phase are a real

challenge for standard one-worm quantum Monte Carlo simulations.

\\ ( http://arXiv.org/abs/cond-mat/0607618 , 62kb)

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Paper: cond-mat/0607619

Date: Mon, 24 Jul 2006 16:05:01 GMT (15kb)

Title: Manipulating Bose-Einstein condensed atoms in toroidal traps

Authors: A. D. Jackson (1), G. M. Kavoulakis (2) ((1) Niels Bohr Institute, (2)

LTH, Lund)

Comments: 4 pages, RevTex, 2 figures

Subj-class: Other

\\

We consider Bose-Einstein condensed atoms confined in a toroidal trap. We

demonstrate that under conditions of one-dimensional behavior, the density

distribution of the atoms may be exponentially localized/delocalized, even for

very small variations in the trapping potential along the torus. This

observation allows one to control the atom density externally via slight

modifications of the trapping potential. For similar reasons, small

irregularities of the trap may also have a very pronounced effect on the

density of the cloud.

\\ ( http://arXiv.org/abs/cond-mat/0607619 , 15kb)

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Paper: cond-mat/0604580

replaced with revised version Sun, 23 Jul 2006 11:08:06 GMT (16kb)

Title: Superfluidity in a Three-flavor Fermi Gas with SU(3) Symmetry

Authors: Lianyi He, Meng Jin and Pengfei Zhuang

Comments: Version accepted for publication in PRA

Subj-class: Other; Superconductivity; Atomic Physics

\\ ( http://arXiv.org/abs/cond-mat/0604580 , 16kb)

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Paper: cond-mat/0605005

replaced with revised version Sat, 22 Jul 2006 01:08:04 GMT (50kb)

Title: Phase Transition in Imbalanced Fermion Superfluids

Authors: Heron Caldas

Comments: This is an invited contribution to a book titled "Pairing beyond BCS

Theory in Fermionic Systems" (Mark Alford, John Clark and Armen Sedrakian,

eds.), to be published by World Scientific. 3 figures, 12 pages. V4: Minor

modifications

Subj-class: Superconductivity; Strongly Correlated Electrons

\\ ( http://arXiv.org/abs/cond-mat/0605005 , 50kb)

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Paper: quant-ph/0607165

Date: Mon, 24 Jul 2006 14:06:18 GMT (12kb)

Title: Models of measurement for quantum fields and for classical continuous

random fields

Authors: Peter Morgan

Comments: This is a submission for the Proceedings of the Vaxjo Conference on

the Foundations of Probability and Physics-4. Comments very welcome

\\

A quantum field model for an experiment describes thermal fluctuations

explicitly and quantum fluctuations implicitly, whereas a comparable continuous

random field model would describe both thermal and quantum fluctuations

explicitly. An ideal classical measurement does not affect the results of later

measurements, in contrast to ideal quantum measurements, but we can describe

the consequences of the thermal and quantum fluctuations of classically

non-ideal measurement apparatuses explicitly. Some details of continuous random

fields and of Bell inequalities for random fields will be discussed.

\\ ( http://arXiv.org/abs/quant-ph/0607165 , 12kb)

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Paper: quant-ph/0603156

replaced with revised version Mon, 24 Jul 2006 05:43:46 GMT (21kb)

Title: Implementing 1 Dimensional Quantum (Hadamard) Walk using Bose-Einstein

Condensate

Authors: C.M. Chandrashekar

Comments: 7 pages, 3 figures

\\ ( http://arXiv.org/abs/quant-ph/0603156 , 21kb)

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Paper: physics/0607215

Date: Mon, 24 Jul 2006 19:55:59 GMT (149kb)

Title: Suppression of Reabsorption via Modulation of Light

Authors: Anthony R. Gorges, Ansel J. Foxley, David M. French, Christopher M.

Ryan, and Jacob L. Roberts

Comments: 5 pages, 4 figures

Subj-class: Atomic Physics

\\

Reabsorption, the multiple scattering of spontaneously emitted photons in

optically thick gases, is a major limitation to efficient optical pumping and

laser cooling in ultracold gases. We report mitigation of reabsorption using

spatial and frequency modulation of laser light illuminating such gases. We

developed a semi-classical model that successfully describes the reabsorption

process when frequency-modulated light is present. It was necessary to extend

the treatment in the model beyond a simple two-atom picture in order to

reproduce our experimental results.

\\ ( http://arXiv.org/abs/physics/0607215 , 124kb)

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Paper: cond-mat/0607630

Date: Tue, 25 Jul 2006 08:11:53 GMT (824kb)

Title: Effect of Quadratic Zeeman Energy on the Vortex of Spinor Bose-Einstein

Condensates

Authors: Tomoya Isoshima and Sungkit Yip

Comments: 6 pages, 5 figures. Published in J. Phys. Soc. Jpn

Subj-class: Other

Journal-ref: J. Phys. Soc. Jpn. 75, 074605 (2006)

DOI: 10.1143/JPSJ.75.074605

\\

The spinor Bose-Einstein condensate of atomic gases has been experimentally

realized by a number of groups. Further, theoretical proposals of the possible

vortex states have been sugessted. This paper studies the effects of the

quadratic Zeeman energy on the vortex states. This energy was ignored in

previous theoretical studies, although it exists in experimental systems. We

present phase diagrams of various vortex states taking into account the

quadratic Zeeman energy. The vortex states are calculated by the

Gross-Pitaevskii equations. Several new kinds of vortex states are found. It is

also found that the quadratic Zeeman energy affects the direction of total

magnetization and causes a significant change in the phase diagrams.

\\ ( http://arXiv.org/abs/cond-mat/0607630 , 824kb)

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Paper: cond-mat/0603571

replaced with revised version Tue, 25 Jul 2006 08:50:34 GMT (406kb)

Title: Identifying the Bose glass phase

Authors: R. Pugatch, N. Bar-gill, N. Katz, E. Rowen, N. Davidson

Comments: 8 pages, 7 figures (expanded version)

Subj-class: Soft Condensed Matter; Other

\\ ( http://arXiv.org/abs/cond-mat/0603571 , 406kb)

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Paper: quant-ph/0607171

Date: Tue, 25 Jul 2006 17:03:05 GMT (622kb)

Title: Quantized Rotation of Atoms From Photons with Orbital Angular Momentum

Authors: M. F. Andersen, C. Ryu, Pierre Clade, V. Natarajan, A. Vaziri, K.

Helmerson, W. D. Phillips

Comments: 5 pages, 4 figures

\\

We demonstrate the coherent transfer of the orbital angular momentum of a

photon to an atom in quantized units of hbar, using a 2-photon stimulated Raman

process with Laguerre-Gaussian beams to generate an atomic vortex state in a

Bose-Einstein condensate of sodium atoms. We show that the process is coherent

by creating superpositions of different vortex states, where the relative phase

between the states is determined by the relative phases of the optical fields.

Furthermore, we create vortices of charge 2 by transferring to each atom the

orbital angular momentum of two photons.

\\ ( http://arXiv.org/abs/quant-ph/0607171 , 622kb)

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Paper: physics/0607223

Date: Tue, 25 Jul 2006 11:31:17 GMT (619kb)

Title: Real Time Relativity

Authors: C. M. Savage, A. C. Searle, L. McCalman

Subj-class: Physics Education; Computational Physics

\\

Real Time Relativity is a computer program that allows the user to fly

through a virtual world governed by relativistic physics. The user controls a

'rocket' carrying a 'camera'. The rocket may be accelerated and steered, and

the camera may be pointed in any direction. It takes advantage of the fact that

video cards provide inexpensive data-parallel processing and are designed to

perform rapid arithmetic on four-dimensional vectors.

\\ ( http://arXiv.org/abs/physics/0607223 , 619kb)

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Paper: physics/0607224

Date: Tue, 25 Jul 2006 15:49:07 GMT (319kb)

Title: Scaling the h-index for different scientific ISI fields

Authors: Juan E. Iglesias and Carlos Pecharroman

Subj-class: Physics and Society

\\

We propose a simple way to put in a common scale the h values of researchers

working in different scientific ISI fields, so that the previsible misuse of

this index for inter-areas comparison might be prevented, or at least,

alleviated.

\\ ( http://arXiv.org/abs/physics/0607224 , 319kb)

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Paper: cond-mat/0607664

Date: Wed, 26 Jul 2006 15:18:00 GMT (302kb)

Title: Superfluid shells for trapped fermions with mass and population

imbalance

Authors: G.-D. Lin, W. Yi and L.-M. Duan

Comments: 4 pages, 3 figures

Subj-class: Other

\\

We map out the phase diagram of strongly interacting fermions in a potential

trap with mass and population imbalance between the two spin components. As a

unique feature distinctively different from the equal-mass case, we show that

the superfluid here forms a shell structure which is not simply connected in

space. Different types of normal states occupy the trap regions inside and

outside this superfluid shell. We calculate the atomic density profiles, which

provide an experimental signature for the superfluid shell structure.

\\ ( http://arXiv.org/abs/cond-mat/0607664 , 302kb)

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Paper: cond-mat/0607667

Date: Wed, 26 Jul 2006 19:18:22 GMT (106kb)

Title: Observation of Heteronuclear Feshbach Molecules from a $^{85}$Rb -

$^{87}$Rb gas

Authors: S. B. Papp and C. E. Wieman

Subj-class: Other

\\

We report on the observation of ultracold heteronuclear Feshbach molecules.

Starting with a $^{87}$Rb BEC and a cold atomic gas of $^{85}$Rb, we utilize

previously unobserved interspecies Feshbach resonances to create up to 25,000

molecules. Even though the $^{85}$Rb gas is non-degenerate we observe a large

molecular conversion efficiency due to the presence of a quantum degenerate

$^{87}$Rb gas; this represents a key feature of our system. We compare the

molecule creation at two different Feshbach resonances with different

magnetic-field widths. The two Feshbach resonances are located at

$265.44\pm0.15$ G and $372.4\pm1.3$ G. We also directly measure the small

binding energy of the molecules through resonant magnetic-field association.

\\ ( http://arXiv.org/abs/cond-mat/0607667 , 106kb)

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Paper: cond-mat/0607692

Date: Wed, 26 Jul 2006 15:03:43 GMT (16kb)

Title: Competing Compressible and Incompressible Phases in Rotating Atomic Bose

Gases at Filling Factor $\nu=2$

Authors: N. R. Cooper and E. H. Rezayi

Subj-class: Mesoscopic Systems and Quantum Hall Effect

\\

We study the groundstates of weakly interacting atomic Bose gases under

conditions of rapid rotation. We present the results of large-scale exact

diagonalisation studies on a periodic geometry (a torus) which allows studies

of compressible states with broken translational symmetry. Focusing on filling

factor $\nu=2$, we show a competition between the triangular vortex lattice, a

quantum smectic state, and the incompressible $k=4$ Read-Rezayi state. We

discuss the corrections arising from finite size effects, and the likely

behaviour for large system sizes. The Read-Rezayi state is stabilised by a

moderate amount of additional dipolar interactions.

\\ ( http://arXiv.org/abs/cond-mat/0607692 , 16kb)

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Paper: cond-mat/0607697

Date: Wed, 26 Jul 2006 17:21:51 GMT (570kb)

Title: Observation of Vortex Pinning in Bose-Einstein Condensates

Authors: S. Tung, V. Schweikhard, E. A. Cornell

Comments: 4 pages, 6 figures

Subj-class: Other

\\

We report the observation of vortex pinning in rotating gaseous Bose-Einstein

condensates (BEC). The vortices are pinned to columnar pinning sites created by

a co-rotating optical lattice superimposed on the rotating BEC. We study the

effects of two different types of optical lattice, triangular and square. With

both geometries we see an orientation locking between the vortex and the

optical lattices. At sufficient intensity the square optical lattice induces a

structural cross-over in the vortex lattice.

\\ ( http://arXiv.org/abs/cond-mat/0607697 , 570kb)

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Paper (*cross-listing*): nucl-th/0607028

Date: Sat, 15 Jul 2006 09:35:37 GMT (615kb)

Title: Nuclear Superconductivity in Compact Stars: BCS Theory and Beyond

Authors: Armen Sedrakian, John W. Clark

Comments: 41 pages, 16 figures. Chapter contributed to "Pairing in Fermionic

Systems: Basic Concepts and Modern Applications", World Scientific

Subj-class: Nuclear Theory; Superconductivity

\\

This chapter provides a review of microscopic theories of pairing in nuclear

systems and neutron stars. Special attention is given to the mean-field BCS

theory and its extensions to include effects of polarization of the medium and

retardation of the interactions. Superfluidity in nuclear systems that exhibit

isospin asymmetry is studied. We further address the crossover from the

weak-coupling BCS description to the strong-coupling BEC limit in dilute

nuclear systems. Finally, within the observational context of rotational

anomalies of pulsars, we discuss models of the vortex state in superfluid

neutron stars and of the mutual friction between superfluid and normal

components, along with the possibility of type-I superconductivity of the

proton subsystem.

\\ ( http://arXiv.org/abs/nucl-th/0607028 , 615kb)

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Paper: cond-mat/0607253

replaced with revised version Wed, 26 Jul 2006 17:53:28 GMT (45kb)

Title: Classifying Novel Phases of Spinor Atoms

Authors: Ryan Barnett, Ari Turner, Eugene Demler

Comments: Added references, corrected typos, minor changes in text

Subj-class: Strongly Correlated Electrons

\\ ( http://arXiv.org/abs/cond-mat/0607253 , 45kb)

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Paper: quant-ph/0607178

Date: Tue, 25 Jul 2006 20:21:40 GMT (781kb)

Title: Electrical detection of 31P spin quantum states

Authors: A. R. Stegner, C. Boehme, H. Huebl, M. Stutzmann, K. Lips and M. S.

Brandt

\\

In recent years, a variety of solid-state qubits has been realized, including

quantum dots, superconducting tunnel junctions and point defects. Due to its

potential compatibility with existing microelectronics, the proposal by Kane

based on phosphorus donors in Si has also been pursued intensively. A key issue

of this concept is the readout of the P quantum state. While electrical

measurements of magnetic resonance have been performed on single spins, the

statistical nature of these experiments based on random telegraph noise

measurements has impeded the readout of single spin states. In this letter, we

demonstrate the measurement of the spin state of P donor electrons in silicon

and the observation of Rabi flops by purely electric means, accomplished by

coherent manipulation of spin-dependent charge carrier recombination between

the P donor and paramagnetic localized states at the Si/SiO2 interface via

pulsed electrically detected magnetic resonance. The electron spin information

is shown to be coupled through the hyperfine interaction with the P nucleus,

which demonstrates the feasibility of a recombination-based readout of nuclear

spins.

\\ ( http://arXiv.org/abs/quant-ph/0607178 , 781kb)

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Paper: quant-ph/0607182

Date: Wed, 26 Jul 2006 14:29:14 GMT (201kb)

Title: Free-Space distribution of entanglement and single photons over 144 km

Authors: R. Ursin, F. Tiefenbacher, T. Schmitt-Manderbach, H. Weier, T.

Scheidl, M. Lindenthal, B. Blauensteiner, T. Jennewein, J. Perdigues, P.

Trojek, B. Oemer, M. Fuerst, M. Meyenburg, J. Rarity, Z. Sodnik, C. Barbieri,

H. Weinfurter, A. Zeilinger

Comments: 10 pages including 2 figures and 1 table

\\

Quantum Entanglement is the essence of quantum physics and inspires

fundamental questions about the principles of nature. Moreover it is also the

basis for emerging technologies of quantum information processing such as

quantum cryptography, quantum teleportation and quantum computation. Bell's

discovery, that correlations measured on entangled quantum systems are at

variance with a local realistic picture led to a flurry of experiments

confirming the quantum predictions. However, it is still experimentally

undecided whether quantum entanglement can survive global distances, as

predicted by quantum theory. Here we report the violation of the

Clauser-Horne-Shimony-Holt (CHSH) inequality measured by two observers

separated by 144 km between the Canary Islands of La Palma and Tenerife via an

optical free-space link using the Optical Ground Station (OGS) of the European

Space Agency (ESA). Furthermore we used the entangled pairs to generate a

quantum cryptographic key under experimental conditions and constraints

characteristic for a Space-to-ground experiment. The distance in our experiment

exceeds all previous free-space experiments by more than one order of magnitude

and exploits the limit for ground-based free-space communication; significantly

longer distances can only be reached using air- or space-based platforms. The

range achieved thereby demonstrates the feasibility of quantum communication in

space, involving satellites or the International Space Station (ISS).

\\ ( http://arXiv.org/abs/quant-ph/0607182 , 201kb)

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Paper: physics/0607234

Date: Wed, 26 Jul 2006 11:19:47 GMT (964kb)

Title: Molecule formation in ultracold atomic gases

Authors: Jeremy M. Hutson and Pavel Soldan

Comments: To be published in International reviews in Physical Chemistry, Vol.

25, issue 4 (October 2006)

Subj-class: Chemical Physics; Atomic Physics

\\

This review describes recent experimental and theoretical advances in forming

molecules in ultracold gases of trapped alkali metal atoms, both by magnetic

tuning through Feshbach resonances and by photoassociation. Molecular

Bose-Einstein condensation of long-range states of both boson dimers and

fermion dimers was achieved in 2002-3. Condensates of boson dimers were found

to be short-lived, but long-lived condensates of fermion dimers have been

produced. Signatures of triatomic and tetraatomic molecules have recently been

observed. Both homonuclear and heteronuclear molecules have been formed by

photoassociation, mostly in very high vibrational levels. Recent attempts to

produce ultracold molecules in short-range states (low vibrational levels) are

described. Experimental and theoretical work on collisions of ultracold

molecules is discussed.

\\ ( http://arXiv.org/abs/physics/0607234 , 964kb)

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Paper: physics/0604079

replaced with revised version Tue, 25 Jul 2006 17:30:04 GMT (594kb)

Title: Magnetic trapping of buffer-gas cooled chromium atoms and prospects for

the extension to paramagnetic molecules

Authors: Joost M. Bakker, Michael Stoll, Dennis R. Weise, Oliver Vogelsang,

Gerard Meijer, and Achim Peters

Comments: 9 pages, 4 Figures. Accepted for J.Phys. B, special issue on cold

molecules/

Subj-class: Atomic Physics

\\ ( http://arXiv.org/abs/physics/0604079 , 594kb)

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Paper: physics/0607034

replaced with revised version Wed, 26 Jul 2006 10:54:36 GMT (200kb)

Title: A Radio-Frequency Atom Chip for Trapping Atoms in Strong-field Seeking

State

Authors: Xiaolin Li, Haichao Zhang, Min Ke, Bo Yan, and Yuzhu Wang

Subj-class: Atomic Physics

\\ ( http://arXiv.org/abs/physics/0607034 , 200kb)

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Paper: cond-mat/0607704

Date: Wed, 26 Jul 2006 23:12:22 GMT (123kb)

Title: Radial and angular rotons in trapped dipolar gases

Authors: Shai Ronen, Daniele C. E. Bortolotti and John. L. Bohn

Comments: 4 pages, 3 figures

Subj-class: Statistical Mechanics

\\

We study Bose-Einstein condensates with purely dipolar interactions in oblate

(pancake) traps. We find that the condensate always becomes unstable to

collapse when the number of particles is sufficiently large. We analyze the

instability, and find that it is the trapped-gas analogue of the

``roton-maxon'' instability previously reported for a gas that is unconfined in

two dimensions. In addition, we find that under certain circumstances, the

condensate wave function attains a biconcave shape, with its maximum density

away from the center of the gas. These biconcave condensates become unstable

due to azimuthl excitation - an angular roton.

\\ ( http://arXiv.org/abs/cond-mat/0607704 , 123kb)

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Paper: cond-mat/0607706

Date: Thu, 27 Jul 2006 00:47:38 GMT (139kb)

Title: Transistor-Like Behavior of a Bose-Einstein Condensate in a Triple Well

Potential

Authors: James A. Stickney, Dana Z. Anderson, and Alex A. Zozulya

Comments: 12 pages, 12 figures

Subj-class: Statistical Mechanics

\\

In the last several years considerable efforts have been devoted to

developing Bose-Einstein Condensate (BEC)-based devices for applications such

as fundamental research, precision measurements and integrated atom optics.

Such devices capable of complex functionality can be designed from simpler

building blocks as is done in microelectronics. One of the most important

components of microelectronics is a transistor. We demonstrate that

Bose-Einstein condensate in a three well potential structure where the

tunneling of atoms between two wells is controlled by the population in the

third, shows behavior similar to that of an electronic field effect transistor.

Namely, it exhibits switching and both absolute and differential gain. The role

of quantum fluctuations is analyzed, estimates of switching time and parameters

for the potential are presented.

\\ ( http://arXiv.org/abs/cond-mat/0607706 , 139kb)

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Paper: cond-mat/0607711

Date: Thu, 27 Jul 2006 08:02:58 GMT (321kb)

Title: Magnon Bose condensation in symmetry breaking magnetic field

Authors: S. V. Maleyev, V. P. Plakhty, S. V. Grigoriev, A. I. Okorokov and A.

V. Syromyatnikov

Comments: Submitted to J. of Phys. Condens. Matter (Proceedings of

International Conference "Highly Frustrated Magnets", Osaka (Japan), August

2006). 8 pages, 5 figures

Subj-class: Strongly Correlated Electrons

\\

Magnon Bose condensation (BC)in the symmetry breaking magnetic field is a

result of unusual form of the Zeeman energy, which has terms linear in the

spin-wave operators and terms mixing excitations differ in the Wave-vector of

the magnetic structure. The following examples are considered: simple

easy-plane tetragonal antiferromagnets (AF), frustrated AF family$R_2Cu O_4$

where $R=Pr,Nd$ etc. and cubic magnets with the Dzyaloshinskii-Moriya

interaction ($Mn Si$ etc.). In all cases the BC becomes important when the

magnetic field becomes comparable with the spin-wave gap. The theory is

illustrated by existing experimental results.

\\ ( http://arXiv.org/abs/cond-mat/0607711 , 321kb)

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Paper: cond-mat/0607718

Date: Thu, 27 Jul 2006 12:25:37 GMT (792kb)

Title: Magnetism and Hund's Rule in an Optical Lattice with Cold Fermions

Authors: K. Karkkainen, M. Borgh, M. Manninen and S. M. Reimann

Comments: 5 pages, 4 figures

Subj-class: Other; Mesoscopic Systems and Quantum Hall Effect

\\

Artificially confined, small quantum systems show a high potential for

employing quantum physics in technology. Ultra-cold atom gases have opened an

exciting laboratory in which to explore many-particle systems that are not

accessible in conventional atomic or solid state physics. It appears promising

that optical trapping of cold bosonic or fermionic atoms will make construction

of devices with unprecedented precision possible in the future, thereby

allowing experimenters to make their samples much more "clean", and hence more

coherent. Trapped atomic quantum gases may thus provide an interesting

alternative to the quantum dot nanostructures produced today. Optical lattices

created by standing laser waves loaded with ultra-cold atoms are an example of

this. They provide a unique experimental setup to study artificial crystal

structures with tunable physical parameters. Here we demonstrate that a

two-dimensional optical lattice loaded with repulsive, contact-interacting

fermions shows a rich and systematic magnetic phase diagram. Trapping a few (N

=< 12) fermions in each of the single-site minima of the optical lattice, we

find that the em shell structure in these quantum wells determines the

magnetism. In a shallow lattice, the tunneling between the lattice sites is

strong, and the lattice is non-magnetic. For deeper lattices, however, the

shell-filling of the single wells with fermionic atoms determines the

magnetism. As a consequence of Hund's first rule, the interaction energy is

lowered by maximizing the number of atoms of the same species. This leads to a

systematic sequence of non-magnetic, ferromagnetic and antiferromagnetic

phases.

\\ ( http://arXiv.org/abs/cond-mat/0607718 , 792kb)

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Paper: cond-mat/0607721

Date: Thu, 27 Jul 2006 13:05:09 GMT (65kb)

Title: Equation of state of an interacting Bose gas at finite temperature: a

Path Integral Monte Carlo study

Authors: S. Pilati, K. Sakkos, J. Boronat, J. Casulleras and S. Giorgini

Comments: 7 pages, 6 figures

Subj-class: Other

\\

By using exact Path Integral Monte Carlo methods we calculate the equation of

state of an interacting Bose gas as a function of temperature both below and

above the superfluid transition. The universal character of the equation of

state for dilute systems and low temperatures is investigated by modeling the

interatomic interactions using different repulsive potentials corresponding to

the same s-wave scattering length. The results obtained for the energy and the

pressure are compared to the virial expansion for temperatures larger than the

critical temperature. At very low temperatures we find agreement with the

ground-state energy calculated using the diffusion Monte Carlo method.

\\ ( http://arXiv.org/abs/cond-mat/0607721 , 65kb)

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Paper: cond-mat/0607722

Date: Thu, 27 Jul 2006 14:07:47 GMT (61kb)

Title: One-dimensional extended Bose-Hubbard model with a confining potential:

a DMRG analysis

Authors: Laura Urba, Emil Lundh, Anders Rosengren

Comments: 14 pages, 11 figures

Subj-class: Strongly Correlated Electrons; Other

\\

The extended Bose-Hubbard model in a quadratic trap potential is studied

using a finite-size density-matrix renormalization group method (DMRG). We

compute the boson density profiles, the local compressibility and the hopping

correlation functions. We observed the phase separation induced by the trap in

all the quantities studied and conclude that the local density approximation is

valid in the extended Bose-Hubbard model. From the plateaus obtained in the

local compressibility it was possible to obtain the phase diagram of the

homogeneous system which is in agreement with previous results.

\\ ( http://arXiv.org/abs/cond-mat/0607722 , 61kb)

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\\

Paper: cond-mat/0607726

Date: Thu, 27 Jul 2006 15:10:48 GMT (223kb)

Title: An effective potential for one-dimensional matter-wave solitons in an

axially inhomogeneous trap

Authors: Sergio De Nicola, Boris A. Malomed, Renato Fedele

Comments: to be published in Physics Letters A

Subj-class: Soft Condensed Matter

\\

We demonstrate that a tight transverse trap with the local frequency, $%

\omega_{\perp}$, gradually varying in the longitudinal direction ($x$) induces

an effective potential for one-dimensional solitons in a self-attractive

Bose-Einstein condensate. An analytical approximation for this potential is

derived by means of a variational method. In the lowest approximation, the

potential is $N(S+1)\omega_{\perp}(x)$, with $N$ the soliton's norm (number of

atoms), and $S$ its intrinsic vorticity (if any). The results can be used to

devise nonuniform traps helping to control the longitudinal dynamics of the

solitons. Numerical verification of the analytical predictions will be

presented elsewhere.

\\ ( http://arXiv.org/abs/cond-mat/0607726 , 223kb)

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Paper: cond-mat/0607730

Date: Thu, 27 Jul 2006 16:16:11 GMT (142kb)

Title: Normal state of a polarized Fermi gas at unitarity

Authors: C. Lobo, A. Recati, S. Giorgini, and S. Stringari

Subj-class: Other

\\

We study the Fermi gas at unitarity and at T=0 by assuming that, at high

polarizations, it is a normal Fermi liquid composed of weakly interacting

quasiparticles associated with the minority spin atoms. With a quantum Monte

Carlo approach we calculate their effective mass and binding energy, as well as

the full equation of state of the normal phase as a function of the

concentration x=n_\down/n_\up of minority atoms. We predict a first order phase

transition from normal to superfluid at x_c=0.44 corresponding, in the presence

of harmonic trapping, to a critical polarization P_c=(N_\up-N_\down)/

(N_\up+N_\down)=77%. We calculate the radii and the density profiles in the

trap and predict that the frequency of the spin dipole mode will be increased

by a factor of 1.23 due to interactions.

\\ ( http://arXiv.org/abs/cond-mat/0607730 , 143kb)

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\\

Paper: cond-mat/0607735

Date: Thu, 27 Jul 2006 17:41:57 GMT (115kb)

Title: Average ground-state energy of finite Fermi systems

Authors: M. Centelles, P. Leboeuf, A. G. Monastra, J. Roccia, P. Schuck, X.

Vinas

Comments: 10 pages, 8 figures

Subj-class: Other

\\

Semiclassical theories like the Thomas-Fermi and Wigner-Kirkwood methods give

a good description of the smooth average part of the total energy of a Fermi

gas in some external potential when the chemical potential is varied. However,

in systems with a fixed number of particles N, these methods overbind the

actual average of the quantum energy as N is varied. We describe a theory that

accounts for this effect. Numerical illustrations are discussed for fermions

trapped in a harmonic oscillator potential and in a hard wall cavity, and for

self-consistent calculations of atomic nuclei. In the latter case, the

influence of deformations on the average behavior of the energy is also

considered.

\\ ( http://arXiv.org/abs/cond-mat/0607735 , 115kb)

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Paper: cond-mat/0601148

replaced with revised version Thu, 27 Jul 2006 15:19:34 GMT (27kb)

Title: Surface Energy in Cold Asymmetrical Fermion Superfluids

Authors: Heron Caldas

Comments: 4 pages, 1 figure, minor corrections, one reference added, title

changed

Subj-class: Superconductivity; Strongly Correlated Electrons

\\ ( http://arXiv.org/abs/cond-mat/0601148 , 27kb)

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Paper: cond-mat/0602626

replaced with revised version Thu, 27 Jul 2006 12:39:19 GMT (160kb)

Title: Bifurcations in Resonance Widths of an Open Bose-Hubbard Dimer

Authors: M. Hiller, T. Kottos, A. Ossipov

Comments: 4 pages, 3 figures

Subj-class: Other

Journal-ref: Phys. Rev. A 73, 063625 (2006)

\\ ( http://arXiv.org/abs/cond-mat/0602626 , 160kb)

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Paper: cond-mat/0605218

replaced with revised version Thu, 27 Jul 2006 10:20:31 GMT (42kb)

Title: Supersolid phases in the one dimensional extended soft core Bosonic

Hubbard model

Authors: G.G. Batrouni, F. Hebert, R.T. Scalettar

Comments: 4 pages, 5 figures

Subj-class: Superconductivity; Statistical Mechanics

\\ ( http://arXiv.org/abs/cond-mat/0605218 , 42kb)

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\\

Paper: cond-mat/0605695

replaced with revised version Thu, 27 Jul 2006 11:54:56 GMT (123kb)

Title: Chaotic ratchet dynamics with cold atoms in a pair of pulsed optical

lattices

Authors: Gabriel G. Carlo, Giuliano Benenti, Giulio Casati, Sandro Wimberger,

Oliver Morsch, Riccardo Mannella, Ennio Arimondo

Comments: 7 pages, 7 figures

Subj-class: Other; Chaotic Dynamics

\\ ( http://arXiv.org/abs/cond-mat/0605695 , 123kb)

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Paper: quant-ph/0607197

Date: Thu, 27 Jul 2006 17:10:38 GMT (572kb)

Title: Towards quantum computing with single atoms and optical cavities on atom

chips

Authors: M. Trupke, J. Metz, A. Beige, and E. A. Hinds

Comments: 14 pages, 6 figures

\\

We report on recent developments in the integration of optical

microresonators into atom chips and describe some fabrication and

implementation challenges. We also review theoretical proposals for quantum

computing with single atoms based on the observation of photons leaking through

the cavity mirrors. The use of measurements to generate entanglement can result

in simpler, more robust and scalable quantum computing architectures. Indeed,

we show that quantum computing with atom-cavity systems is feasible even in the

presence of relatively large spontaneous decay rates and finite photon detector

efficiencies.

\\ ( http://arXiv.org/abs/quant-ph/0607197 , 572kb)

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\\

Paper (*cross-listing*): gr-qc/0603112

replaced with revised version Wed, 26 Jul 2006 20:22:38 GMT (10kb)

Title: Quantum gravitational decoherence of matter waves

Authors: Charles H.-T. Wang, Robert Bingham and J. Tito Mendonca

Comments: 8 pages; final version to appear in CQG as a letter

\\ ( http://arXiv.org/abs/gr-qc/0603112 , 10kb)

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Till next time (whenever that is),

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/ ========================================================================= 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 Fri Jul 28 2006 - 19:48:42 EST

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