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

Date: Tue, 20 Jun 2006 09:17:38 +1000 (EST)

Date: Tue, 20 Jun 2006 09:17:38 +1000 (EST)

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

Hi all,

Apologies for being a day late yet again... I have included the first mailing

from this week as well.

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

The abstracts:

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Paper: cond-mat/0606226

Date: Fri, 9 Jun 2006 00:42:28 GMT (75kb)

Title: Josephson effect and quantum merging of two Bose superfluids

Authors: Hongwei Xiong, Shujuan Liu, Mingsheng Zhan

Comments: 9 pages, 4 figures

Subj-class: Superconductivity; Other

Journal-ref: PHYSICAL REVIEW B 73, 224505 (2006)

\\

We consider the Josephson effect when two independent Bose superfluids are

weakly connected. In the presence of interparticle interaction and based on the

calculations of the one-particle density matrix of the whole system, we find

that the one-particle density matrix can be factorized which satisfies the

general criterion of Bose superfluid proposed by Penrose and Onsager. By

introducing an effective order parameter for the whole system, our researches

show that there is Josephson effect for two independent Bose superfluids.

\\ ( http://arXiv.org/abs/cond-mat/0606226 , 75kb)

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Paper: cond-mat/0606243

Date: Fri, 9 Jun 2006 13:39:29 GMT (304kb)

Title: A 'Wheel' and 'Axle' description of the Bogoliubov-Anderson phonon in

the BEC/BCS crossover

Authors: Da-Shin Lee, Chi-Yong Lin and Ray J. Rivers

Comments: Four pages, 2 figures

Subj-class: Other

\\

We show that the properties of the gapless mode of the BEC/BCS crossover in

the presence of a Feshbach resonance at T=0 can be derived easily from the

derivative expansion of the exact (one-loop) effective action. In particular,

from a simple 'wheel' and 'axle' phonon action, we calculate the sound

velocity, both analytically and numerically, throughout the BCS and BEC

regimes.

\\ ( http://arXiv.org/abs/cond-mat/0606243 , 304kb)

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Paper: cond-mat/0606255

Date: Fri, 9 Jun 2006 19:13:00 GMT (316kb)

Title: Bose-Fermi mixtures in 1D optical superlattices

Authors: F. Schmitt, M. Hild, R. Roth

Comments: 18 pages, 9 figures

Subj-class: Statistical Mechanics

\\

The zero temperature phase diagram of binary boson-fermion mixtures in

two-colour superlattices is investigated. The eigenvalue problem associated

with the Bose-Fermi-Hubbard Hamiltonian is solved using an exact numerical

diagonalization technique, supplemented by an adaptive basis truncation scheme.

The physically motivated basis truncation allows to access larger systems in a

fully controlled and very flexible framework. Several experimentally relevant

observables, such as the matter-wave interference pattern and the

condensatefraction, are investigated in order to explore the rich phase

diagram. At symmetric half filling a phase similar to the Mott-insulating phase

in a commensurate purely bosonic system is identified and an analogy to recent

experiments is pointed out. Furthermore a phase of complete localization of the

bosonic species generated by the repulsive boson-fermion interaction is

identified. These localized condensates are of a different nature than the

genuine Bose-Einstein condensates in optical lattices.

\\ ( http://arXiv.org/abs/cond-mat/0606255 , 316kb)

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Paper: quant-ph/0606065

Date: Thu, 8 Jun 2006 03:39:59 GMT (52kb)

Title: Perfect quantum state transfer with spinor bosons on weighted graphs

Authors: David L. Feder

Comments: 4 pages, 2 figures, revtex

Subj-class: Quantum Physics; Other

\\

A duality between the properties of many spinor bosons on a regular lattice

and those of a single particle on a weighted graph reveals that a quantum

particle can traverse an infinite hierarchy of networks with perfect

probability in polynomial time, even as the number of nodes increases

exponentially. The one-dimensional `quantum wire' and the hypercube are special

cases in this construction, where the number of spin degrees of freedom is

equal to one and the number of particles, respectively. An implementation of

near-perfect quantum state transfer across a weighted parallelepiped with

ultracold atoms in optical lattices is discussed.

\\ ( http://arXiv.org/abs/quant-ph/0606065 , 52kb)

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Paper: quant-ph/0606074

Date: Thu, 8 Jun 2006 15:09:33 GMT (145kb)

Title: Conservative chaotic map as a model of quantum many-body environment

Authors: Davide Rossini, Giuliano Benenti, Giulio Casati

Comments: 8 pages, 4 figures

Subj-class: Quantum Physics; Statistical Mechanics; Chaotic Dynamics

\\

We study the dynamics of the entanglement between two qubits coupled to a

common chaotic environment, described by the quantum kicked rotator model. We

show that the kicked rotator, which is a single-particle deterministic

dynamical system, can reproduce the effects of a pure dephasing many-body bath.

Indeed, in the semiclassical limit the interaction with the kicked rotator can

be described as a random phase-kick, so that decoherence is induced in the

two-qubit system. We also show that our model can efficiently simulate

non-Markovian environments.

\\ ( http://arXiv.org/abs/quant-ph/0606074 , 145kb)

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Paper: cond-mat/0408460

replaced with revised version Fri, 9 Jun 2006 16:11:26 GMT (108kb)

Title: Vortices and Ring Solitons in Bose-Einstein Condensates

Authors: L. D. Carr and Charles W. Clark

Comments: 15 pages, 9 figures -- major revision

Subj-class: Other; Pattern Formation and Solitons

\\ ( http://arXiv.org/abs/cond-mat/0408460 , 108kb)

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Paper: cond-mat/0603319

replaced with revised version Fri, 9 Jun 2006 11:31:07 GMT (301kb)

Title: Simulations of ultracold bosonic atoms in optical lattices with

anharmonic traps

Authors: Olivier Gygi, Helmut G. Katzgraber, Matthias Troyer, Stefan Wessel,

and G. George Batrouni

Comments: 8 pages, 8 figures, 2 tables

Subj-class: Other

Journal-ref: Phys. Rev. A 73, 063606 (2006)

DOI: 10.1103/PhysRevA.73.063606

\\ ( http://arXiv.org/abs/cond-mat/0603319 , 301kb)

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Paper: quant-ph/0606082

Date: Fri, 9 Jun 2006 10:48:11 GMT (164kb)

Title: Microwave potentials and optimal control for robust quantum gates on an

atom chip

Authors: Philipp Treutlein, Theodor W. H\"ansch, Jakob Reichel, Antonio

Negretti, Markus A. Cirone, Tommaso Calarco

Comments: 14 pages, 7 figures, 1 table

\\

We propose a two-qubit collisional phase gate that can be implemented with

available atom chip technology, and present a detailed theoretical analysis of

its performance. The gate is based on earlier phase gate schemes, but uses a

qubit state pair with an experimentally demonstrated, very long coherence

lifetime. Microwave near-fields play a key role in our implementation as a

means to realize the state-dependent potentials required for conditional

dynamics. Quantum control algorithms are used to optimize gate performance. We

employ circuit configurations that can be built with current fabrication

processes, and extensively discuss the impact of technical noise and

imperfections that characterize an actual atom chip. We find an overall

infidelity compatible with requirements for fault-tolerant quantum computation.

\\ ( http://arXiv.org/abs/quant-ph/0606082 , 164kb)

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Paper: quant-ph/0606087

Date: Fri, 9 Jun 2006 14:54:05 GMT (234kb)

Title: Single atom quantum walk with 1D optical superlattices

Authors: Jaewoo Joo, P. L. Knight, and Jiannis K. Pachos

Comments: 6 pages, 7 figures

\\

A proposal for the implementation of quantum walks using cold atom technology

is presented. It consists of one atom trapped in time varying optical

superlattices. The required elements are presented in detail including the

preparation procedure, the manipulation required for the quantum walk evolution

and the final measurement. These procedures can be, in principle, implemented

with present technology.

\\ ( http://arXiv.org/abs/quant-ph/0606087 , 234kb)

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Paper: quant-ph/0605163

replaced with revised version Fri, 9 Jun 2006 13:13:14 GMT (617kb)

Title: Quantum Information Processing in Optical Lattices and Magnetic

Microtraps

Authors: Philipp Treutlein, Tilo Steinmetz, Yves Colombe, Benjamin Lev, Peter

Hommelhoff, Jakob Reichel, Markus Greiner, Olaf Mandel, Arthur Widera, Tim

Rom, Immanuel Bloch, and Theodor W. H\"ansch

Comments: 15 pages, 11 figures, corrected author list

\\ ( http://arXiv.org/abs/quant-ph/0605163 , 617kb)

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Paper: cond-mat/0606262

Date: Sat, 10 Jun 2006 14:04:49 GMT (191kb)

Title: One-dimensional description of a Bose-Einstein condensate in a rotating

closed-loop waveguide

Authors: S. Schwartz, M. Cozzini, C. Menotti, I. Carusotto, P. Bouyer, S.

Stringari

Subj-class: Other

\\

We propose a general procedure for reducing the three-dimensional Schrodinger

equation for atoms moving along a strongly confining atomic waveguide to an

effective one-dimensional equation. This procedure is applied to the case of a

rotating closed-loop waveguide. The possibility of including mean-field atomic

interactions is presented. Application of the general theory to characterize a

new concept of atomic waveguide based on optical tweezers is finally discussed.

\\ ( http://arXiv.org/abs/cond-mat/0606262 , 191kb)

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Paper: cond-mat/0606265

Date: Sat, 10 Jun 2006 19:45:04 GMT (177kb)

Title: Spinful bosons in an optical lattice

Authors: Sara Bergkvist, Ian McCulloch, Anders Rosengren

Comments: 9 pages, 13 figures

Subj-class: Other

\\

The phase diagram of spinful bosons in a one-dimensional optical lattice has

been obtained using density matrix renormalization group calculations.

Correlation functions and the dimerization are shown and we also present

results for the energy gap between ground state and the spin excited states. We

confirm the anticipated phase diagram, with Mott-insulating regions of

alternating dimerized S=1 chains for odd particle density versus on-site

singlets for even density. We find no evidence for any additional ordered

phases in the physically accessible region, however for sufficiently large spin

interaction, on-site singlet pairs dominate leading, for odd density, to a

breakdown of the Mott insulator or, for even density, a real-space singlet

superfluid.

\\ ( http://arXiv.org/abs/cond-mat/0606265 , 177kb)

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Paper: cond-mat/0606268

Date: Sun, 11 Jun 2006 00:18:12 GMT (881kb)

Title: Many-body studies on atomic quantum systems

Authors: Jordi Mur-Petit

Comments: PhD thesis with 216 pages and 48 figures; uses pdflatex. Some figures

have been submitted at low resolution to fit arXiv's memory limitations. The

"complete" version can be downloaded from

http://www.tesisenxarxa.net/TDX-0426106-152454/

Subj-class: Other

\\

This thesis presents a set of studies on atomic systems where quantum effects

are particularly relevant. These studies have been developed by applying a

variety of tools from many-body physics.

First of all, we have studied the prospects for the existence of a superfluid

transition in an ultracold gas of fermionic atoms, by generalizing the BCS

theory of superconductivity to the case when the two species that pair have

different densities and the ground state may spontaneously break one or more

symmetries.

In a second part, we have studied the dynamics of a Bose-Einstein condensate

whose spin degree of freedom is free to evolve inside a quasi-onedimensional

optical trap. We have used a mean-field formulation to address both the zero

temperature case and the finite temperature one.

Finally, we have performed a careful study of the ground state and the line

tension of two-dimensional systems of helium-4. First, we have used Monte Carlo

techniques, then with a Density Functional built on-purpose.

Comments are welcome!

KEYWORDS: Cold gases, Pairing, Spinor condensate, Helium, Two dimensions

\\ ( http://arXiv.org/abs/cond-mat/0606268 , 881kb)

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Paper: cond-mat/0606281

Date: Mon, 12 Jun 2006 12:58:54 GMT (886kb)

Title: A Primary Noise Thermometer for Ultracold Bose Gases

Authors: R. Gati, J. Esteve, B. Hemmerling, T. B. Ottenstein, J. Appmeier, A.

Weller, M. K. Oberthaler

Comments: 18 pages, 8 figures

Subj-class: Other

\\

We discuss in detail the experimental investigation of thermally induced

fluctuations of the relative phase between two weakly coupled Bose-Einstein

condensates. In analogy to superconducting Josephson junctions, the weak

coupling originates from a tunneling process through a potential barrier which

is obtained by trapping the condensates in an optical double-well potential.

The observed fluctuations of the relative phase are in quantitative agreement

with a many body two mode model at finite temperature. The agreement

demonstrates the possibility of using the phase fluctuation measurements in a

bosonic Josephson junction as a primary thermometer. This new method allows for

measuring temperatures far below the critical temperature where standard

methods based on time of flight measurements fail. We employ this new

thermometer to probe the heat capacity of a degenerate Bose gas as a function

of temperature.

\\ ( http://arXiv.org/abs/cond-mat/0606281 , 886kb)

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Paper: cond-mat/0606288

Date: Mon, 12 Jun 2006 15:13:46 GMT (47kb)

Title: Spontaneous Circulation in Ground-State Spinor Dipolar Bose-Einstein

Condensates

Authors: Yuki Kawaguchi, Hiroki Saito, and Masahito Ueda

Comments: 4 pages, 4 figures (include one color figure)

Subj-class: Other

\\

We have found three ground-state phases in a spin-1 ferromagnetic

Bose-Einstein condensate with magnetic dipole-dipole interactions. A

substantial orbital angular momentum accompanied by chiral symmetry breaking is

shown to spontaneously emerge in a certain parameter regime. All the phases can

be realized in the spin-1 $^{87}$Rb condensate by changing the number of atoms

or the trap frequency.

\\ ( http://arXiv.org/abs/cond-mat/0606288 , 47kb)

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Paper (*cross-listing*): nlin.PS/0606016

Date: Mon, 5 Jun 2006 20:52:31 GMT (12kb)

Title: On existence of dark solitons in cubic-quintic nonlinear Schr\"{o}dinger

equation with a periodic potential

Authors: Pedro J. Torres, Vladimir V. Konotop

Comments: 10 pages

Subj-class: Pattern Formation and Solitons; Chaotic Dynamics; Other

\\

A proof of existence of stationary dark soliton solutions of the

cubic-quintic nonlinear Schr\"{o}dinger equation with a periodic potential is

given. It is based on the interpretation of the dark soliton as a heteroclinic

on the Poincar\'e map.

\\ ( http://arXiv.org/abs/nlin/0606016 , 12kb)

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Paper: cond-mat/0603384

replaced with revised version Mon, 12 Jun 2006 11:59:46 GMT (103kb)

Title: Expansion of a Fermi Cloud in the BCS-BEC Crossover

Authors: Giovanni Diana, Nicola Manini, Luca Salasnich

Comments: 5 pages, 3 figures

Subj-class: Statistical Mechanics

Journal-ref: Phys. Rev. A 73, 065601 (2006)

\\ ( http://arXiv.org/abs/cond-mat/0603384 , 103kb)

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Paper: cond-mat/0605393

replaced with revised version Fri, 9 Jun 2006 20:49:10 GMT (113kb)

Title: Bose-Einstein condensates in RF-dressed adiabatic potentials

Authors: M. White, H. Gao, M. Pasienski, B. DeMarco

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0605393 , 113kb)

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Paper: physics/0501146

replaced with revised version Fri, 9 Jun 2006 09:05:12 GMT (193kb)

Title: Quantum Accelerator Modes from the Farey Tree

Authors: A. Buchleitner, M. B. d'Arcy, S. Fishman, S. A. Gardiner, I. Guarneri,

Z.-Y. Ma, L. Rebuzzini, G. S. Summy

Comments: Final published version

Subj-class: Atomic Physics; Chaotic Dynamics

Journal-ref: Phys. Rev. Lett. 96, 164101 (2006)

DOI: 10.1103/PhysRevLett.96.164101

\\ ( http://arXiv.org/abs/physics/0501146 , 193kb)

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Paper: cond-mat/0606319

Date: Tue, 13 Jun 2006 09:26:28 GMT (17kb)

Title: Off-diagonal correlations of lattice impenetrable bosons in one

dimension

Authors: D.M. Gangardt, G.V. Shlyapnikov

Comments: 10 pages. Submitted to the Focus Issue on 'Cold Atoms in Optical

Lattices' of New Journal of Physics

Subj-class: Statistical Mechanics

\\

We consider off-diagonal correlation functions of impenetrable bosons on a

lattice. By using the Jordan-Wigner transformation the one-body density matrix

is represented as (Toeplitz) determinant of a matrix of fermionic Green

functions. Using the replica method we calculate exactly the full long-range

asymptotic behaviour of the one-body density matrix. We discuss how subleading

oscillating terms, originating from short-range correlations give rise to

interesting features in the momentum distribution.

\\ ( http://arXiv.org/abs/cond-mat/0606319 , 17kb)

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Paper: cond-mat/0606322

Date: Tue, 13 Jun 2006 10:59:38 GMT (746kb)

Title: Finite Temperature Phase Diagram of a Two-Component Fermi Gas with

Density Imbalance

Authors: Lianyi He, Meng Jin and Pengfei Zhuang

Comments: 10 pages, 10 figures

Subj-class: Superconductivity; Other

\\

We investigated possible superfluid phases at finite temperature in a

two-component Fermi gas with density imbalance. In the frame of a general

four-fermion interaction theory, we solved the gap equations for the pairing

gap and pairing momentum under the restriction of fixed number densities, and

analyzed the stability of different phases by calculating the superfluid

density and number susceptibilities. The homogeneous superfluid is stable only

at high temperature and low number asymmetry, the inhomogeneous LOFF survives

at low temperature and high number asymmetry, and in between them there exists

another possible inhomogeneous phase, the phase separation. The critical

temperatures and the orders of the phase transitions among the superfluid

phases and normal phase are calculated analytically and numerically. The phase

diagram we obtained in the temperature and number asymmetry plane is quite

different from the one in temperature and chemical potential difference plane

for a system with fixed chemical potentials.

\\ ( http://arXiv.org/abs/cond-mat/0606322 , 746kb)

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Paper: cond-mat/0606327

Date: Tue, 13 Jun 2006 13:01:44 GMT (322kb)

Title: Single quantum realization of a collision of two Bose--Einstein

condensates

Authors: J. Chwedenczuk, P. Zin, K. Rzazewski and M. Trippenbach

Comments: 4 pages, 1 figure

Subj-class: Other

\\

We propose a method for simulating a single realization of a collision of two

Bose--Einstein condensates. Recently in Zi\'{n} {\it et al.} (Phys. Rev. Lett.

{\bf 94}, 200401 (2005)) we introduced a quantum model of an incoherent elastic

scattering in a collision of two counter-propagating atomic Gaussian

wavepackets. Here show that this model is capable of generating the data that

can be interpreted as results of a single collision event. We find a range of

parameters, including relative velocity, population and the size of colliding

condensates, where the structure of hallo of scattered atoms in a single

realization strongly differs from that averaged over many realizations.

\\ ( http://arXiv.org/abs/cond-mat/0606327 , 322kb)

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Paper: cond-mat/0606330

Date: Tue, 13 Jun 2006 14:41:46 GMT (622kb)

Title: Sarma Phase in Trapped Unbalanced Fermi Gases

Authors: K. B. Gubbels, M. W. J. Romans, and H. T. C. Stoof

Comments: 4 pages, 3 figures

Subj-class: Statistical Mechanics

\\

We consider a trapped unbalanced Fermi gas at nonzero temperatures where the

superfluid Sarma phase is stable. We determine in particular the phase

boundaries between the superfluid, normal, and phase separated regions of the

trapped unbalanced Fermi mixture. We show that the physics of the Sarma phase

is sufficient to understand the recent observations of Zwierlein et al.

[Science 311, 492 (2006); cond-mat/0605258] and indicate how the apparent

contradictions between this experiment and the experiment of Partridge et al.

[Science 311, 503 (2006)] may be resolved.

\\ ( http://arXiv.org/abs/cond-mat/0606330 , 622kb)

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Paper: quant-ph/0606097

Date: Mon, 12 Jun 2006 18:37:56 GMT (53kb)

Title: Strongly Interacting Polaritons in Coupled Arrays of Cavities

Authors: Michael J. Hartmann, Fernando G.S.L. Brandao and Martin B. Plenio

Comments: 7 pages, 5 figures

Subj-class: Quantum Physics; Other

\\

The experimental observation of quantum phenomena in strongly correlated many

particle systems is difficult because of the short length- and timescales

involved. Obtaining at the same time detailed control of individual

constituents appears even more challenging and thus to date inhibits employing

such systems as quantum computing devices. Substantial progress to overcome

these problems has been achieved with cold atoms in optical lattices, where a

detailed control of collective properties is feasible but it is very difficult

to address and hence control or measure individual sites. Here we show, that

polaritons, combined atom and photon excitations, in an array of cavities such

as a photonic crystal or coupled toroidal micro-cavities, can form a strongly

interacting many body system, where individual particles can be controlled and

measured. All individual building blocks of the proposed setting have already

been experimentally realised, thus demonstrating the potential of this device

as a quantum simulator.

\\ ( http://arXiv.org/abs/quant-ph/0606097 , 53kb)

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Paper: quant-ph/0606101

Date: Mon, 12 Jun 2006 21:57:28 GMT (14kb)

Title: Quantum Computation Using Vortices and Majorana Zero Modes of a $p_x$ +

$ip_y$ Superfluid of Fermionic Cold Atoms

Authors: Sumanta Tewari, S. Das Sarma, Chetan Nayak, Chuanwei Zhang, P. Zoller

\\

We propose to use the recently predicted two-dimensional `weak-pairing' $p_x

+ ip_y$ superfluid state of fermionic cold atoms as a platform for topological

quantum computation. In the core of a vortex, this state supports a zero-energy

Majorana mode, which moves to finite energy in the corresponding topologically

trivial `strong-pairing' state. By braiding vortices in the `weak-pairing'

state, unitary quantum gates can be applied to the Hilbert space of Majorana

zero-modes. For read-out of the topological qubits, we propose realistic

schemes suitable for atomic superfluids.

\\ ( http://arXiv.org/abs/quant-ph/0606101 , 14kb)

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Paper: quant-ph/0606104

Date: Tue, 13 Jun 2006 03:13:54 GMT (144kb)

Title: Cooling to the Ground State of Axial Motion for One Atom Strongly

Coupled to an Optical Cavity

Authors: A. D. Boozer, A. Boca, R. Miller, T. E. Northup, H. J. Kimble

Comments: 5 pages, 4 figures

\\

Localization to the ground state of axial motion is demonstrated for a

single, trapped atom strongly coupled to the field of a high finesse optical

resonator. The axial atomic motion is cooled by way of coherent Raman

transitions on the red vibrational sideband. An efficient state detection

scheme enabled by strong coupling in cavity QED is used to record the Raman

spectrum, from which the state of atomic motion is inferred. We find that the

lowest vibrational level of the axial potential with zero-point energy 13uK is

occupied with probability P0~0.95.

\\ ( http://arXiv.org/abs/quant-ph/0606104 , 144kb)

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Paper: quant-ph/0606110

Date: Tue, 13 Jun 2006 13:57:39 GMT (17kb)

Title: Entanglement in Spin Waves with Binary Dipolar Atoms in a 2D Optical

Lattice

Authors: H. T. Ng and K. Burnett

Comments: 5 pages, 3 figures

\\

We study the area-dependent entropy and two-site entanglement in the spin

waves with binary interacting dipolar Bose-Einstein condensates in a 2D optical

lattice. The two species condensates at each site behave like an ensemble of

spin-half particles with the interaction to its nearest neighbors and next

nearest neighbors. We show that the ground state of a Bose-Einstein condensate

lattice with nearest-neighbor and next-nearest-neighbor interactions exhibits

spin wave and can be mapped into a harmonic lattice. The critical behavior of

the area-dependent entropy and two-site entanglement is examined in the

vicinity of a quantum phase transition.

\\ ( http://arXiv.org/abs/quant-ph/0606110 , 17kb)

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Paper: quant-ph/0606113

Date: Tue, 13 Jun 2006 16:17:02 GMT (353kb)

Title: Inserting two atoms into a single optical micropotential

Authors: Y. Miroshnychenko, W. Alt, I. Dotsenko, L. Foerster, M. Khudaverdyan,

D. Meschede, S. Reick, and A. Rauschenbeutel

Comments: 4 pages, 4 figures

\\

We recently demonstrated that strings of trapped atoms inside a standing wave

optical dipole trap can be rearranged using optical tweezers [Y. Miroshnychenko

et al., Nature, in press (2006)]. This technique allows us to actively set the

interatomic separations on the scale of the individual trapping potential

wells. Here, we use such a distance-control operation to insert two atoms into

the same potential well. The detected success rate of this manipulation is

16(+4/-3) %, in agreement with the predictions of a theoretical model based on

our independently determined experimental parameters.

\\ ( http://arXiv.org/abs/quant-ph/0606113 , 353kb)

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Paper: cond-mat/0606345

Date: Tue, 13 Jun 2006 23:25:13 GMT (310kb)

Title: First-principles quantum simulations of dissociation of molecular

condensates: Atom correlations in momentum space

Authors: C.M. Savage, P. Schwenn, K.V. Kheruntsyan

Comments: 17 pages, 6 figures

Subj-class: Other; Statistical Mechanics

\\

We investigate the quantum many-body dynamics of dissociation of a

Bose-Einstein condensate of molecular dimers into pairs of constituent bosonic

atoms and analyze the resulting atom-atom correlations. The quantum fields of

both the molecules and atoms are simulated from first principles in three

dimensions using the positive-P representation method. This allows us to

provide an exact treatment of the molecular field depletion and s-wave

scattering interactions between the particles, as well as to extend the

analysis to nonuniform systems. In the simplest uniform case, we find that the

major source of atom-atom decorrelation is atom-atom recombination which

produces molecules outside the initially occupied condensate mode. The unwanted

molecules are formed from dissociated atom pairs with non-opposite momenta. The

net effect of this process -- which becomes increasingly significant for

dissociation durations corresponding to more than about 40% conversion -- is to

reduce the atom-atom correlations. In addition, for nonuniform systems we find

that mode-mixing due to inhomogeneity can result in further degradation of the

correlation signal. We characterize the correlation strength via the degree of

squeezing of particle number-difference fluctuations in a certain

momentum-space volume and show that the correlation strength can be increased

if the signals are binned into larger counting volumes.

\\ ( http://arXiv.org/abs/cond-mat/0606345 , 310kb)

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Paper: cond-mat/0606353

Date: Wed, 14 Jun 2006 07:11:04 GMT (170kb)

Title: Generalized exclusion statistics and degenerate signature of strongly

interacting anyons

Authors: M T Batchelor and X W Guan

Comments: 4 pages, 2 figures

Subj-class: Statistical Mechanics; Strongly Correlated Electrons

\\

We show that below the degenerate temperature the distribution profiles of

strongly interacting anyons in one dimension coincide with the most probable

distributions of ideal particles obeying generalized exclusion statistics

(GES). The thermodynamics and the local two-particle correlation function

derived from the GES are in good agreement with the results derived for the

anyon model using the thermodynamic Bethe Ansatz. The anyonic interaction and

the dynamical interaction implement a continuous range of GES, providing a

signature of strongly interacting anyons, including the strongly interacting 1D

Bose gas.

\\ ( http://arXiv.org/abs/cond-mat/0606353 , 170kb)

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Paper: cond-mat/0606363

Date: Wed, 14 Jun 2006 09:44:21 GMT (19kb)

Title: Nonequivalent operator representations for Bose-condensed systems

Authors: V.I. Yukalov

Comments: Latex file, 27 pages, no figures

Subj-class: Statistical Mechanics

Journal-ref: Laser Phys. 16 (2006) 511-525

\\

The necessity of accurately taking into account the existence of

nonequivalent operator representations, associated with canonical

transformations, is discussed. It is demonstrated that Bose systems in the

presence of the Bose-Einstein condensate and without it correspond to different

Fock spaces, orthogonal to each other. A composite representation for the field

operators is constructed, allowing for a self-consistent description of

Bose-condensed systems. Equations of motion are derived from the given

Hamiltonian, which guarantees the validity of conservation laws and

thermodynamic self-consistency. At the same time, the particle spectrum,

obtained either from diagonalizing this Hamiltonian or from linearizing the

field-operator equations of motion, has no gap. The condition of the condensate

existence assures the absence of the gap in the spectrum, irrespectively to the

approximation involved. The suggested self-consistent theory is both conserving

and gapless.

\\ ( http://arXiv.org/abs/cond-mat/0606363 , 19kb)

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\\

Paper: cond-mat/0606383

Date: Wed, 14 Jun 2006 19:35:42 GMT (22kb)

Title: Coherent impurity motion in a strongly correlated hard-core boson

quantum solid

Authors: Efstratios Manousakis

Comments: four two-column Revtex pages, 2 figures

Subj-class: Strongly Correlated Electrons; Statistical Mechanics

\\

A quantum lattice gas model is proposed to capture the essential aspects of

the motion of an impurity in a purely bosonic strongly correlated quantum solid

(such as a He-3 atom in solid He-4). Within the ``spin''-wave approximation the

model reduces to an effective Hamiltonian in which the impurity motion couples

linearly to bosonic excitations and in the non-crossing approximation we solve

the Dyson's equations for the impurity Green's functions for the square

lattice. We find that both substitutional and interstitial impurity

quasiparticles form sharp well-defined coherent low-energy excitations. We

discuss the possible relevance of our results to the superfluidity of solid

He-4.

\\ ( http://arXiv.org/abs/cond-mat/0606383 , 22kb)

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\\

Paper: cond-mat/0605184

replaced with revised version Wed, 14 Jun 2006 11:59:12 GMT (851kb)

Title: A Mott state of molecules

Authors: T. Volz, N. Syassen, D. M. Bauer, E. Hansis, S. D\"urr, G. Rempe

Subj-class: Statistical Mechanics

\\ ( http://arXiv.org/abs/cond-mat/0605184 , 851kb)

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\\

Paper: quant-ph/0606122

Date: Wed, 14 Jun 2006 15:37:20 GMT (37kb)

Title: Is the Fair Sampling Assumption supported by EPR Experiments?

Authors: Guillaume Adenier and Andrei Yu. Khrennikov

Comments: 6 pages, 8 figures

\\

We analyse optical EPR experimental data performed by Weihs et al in

Innsbruck 1997-1998. We show that for some linear combinations of the raw

coincidence rates, the experimental results display some anomalous behavior

that a more general source state (like non-maximally entangled state) cannot

straightforwardly account for. We attempt to explain these anomalies by taking

account of the relative efficiencies of the four channels. For this purpose, we

use the fair sampling assumption, and assume explicitly that the detection

efficiencies for the pairs of entangled photons can be written as a product of

the two corresponding detection efficiencies for the single photons. Although

the explicit use of the Fair Sampling assumption does reduce the magnitude of

observed anomalies, we show that is is however insufficient to remove them

completely.

\\ ( http://arXiv.org/abs/quant-ph/0606122 , 37kb)

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\\

Paper: physics/0606126

Date: Wed, 14 Jun 2006 16:48:02 GMT (224kb)

Title: Atom interferometry gravity-gradiometer for the determination of the

Newtonian gravitational constant G

Authors: A. Bertoldi, G. Lamporesi, L. Cacciapuoti, M. de Angelis, M. Fattori,

T. Petelski, A. Peters, M. prevedelli, J. Stuhler, G. M. Tino

Comments: 9 pages,9 figures, Submitted

Subj-class: Atomic Physics; General Physics

\\

We developed a gravity-gradiometer based on atom interferometry for the

determination of the Newtonian gravitational constant \textit{G}. The

apparatus, combining a Rb fountain, Raman interferometry and a juggling scheme

for fast launch of two atomic clouds, was specifically designed to reduce

possible systematic effects. We present instrument performances and show that

the sensor is able to detect the gravitational field induced by source masses.

A discussion of projected accuracy for \textit{G} measurement using this new

scheme shows that the results of the experiment will be significant to

discriminate between previous inconsistent values.

\\ ( http://arXiv.org/abs/physics/0606126 , 224kb)

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\\

Paper: cond-mat/0606398

Date: Thu, 15 Jun 2006 06:47:47 GMT (984kb)

Title: Landau damping: instability mechanism of superfluid Bose gases moving in

optical lattices

Authors: Kiyohito Iigaya, Satoru Konabe, Ippei Danshita, and Tetsuro Nikuni

Comments: 9 pages, 5 figures

Subj-class: Other

\\

We investigate Landau damping of Bogoliubov excitations in a dilute Bose gas

moving in an optical lattice at finite temperatures. Using a 1D tight-binding

model, we explicitly obtain the Landau damping rate, the sign of which

determines the stability of the condensate. We find that the sign changes at a

certain condensate velocity, which is exactly the same as the critical velocity

determined by the Landau criterion of superfluidity. This coincidence of the

critical velocities reveals the microscopic mechanism of the Landau

instability. This instability mechanism is also consistent with the recent

experiment suggesting that a thermal cloud plays a crucial role in breakdown of

superfluids, since the thermal cloud is also vital in the Landau damping

process. We also examine the possibility of simultaneous disappearance of all

damping processes.

\\ ( http://arXiv.org/abs/cond-mat/0606398 , 984kb)

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\\

Paper: cond-mat/0606409

Date: Thu, 15 Jun 2006 11:35:43 GMT (20kb)

Title: Ground State of a System of N Hard Core Quantum Particles in 1D Box

Authors: Yatendra S Jain

Comments: 19 pages, no figures

Subj-class: Soft Condensed Matter

\\

The ground state of a system of $N$ impenetrable hard core quantum particles

in a 1-D box is analyzed by using a new scheme applied recently to study a

similar system of two such particles {\it [Centl. Eur. J. Phys., 2(4), 709

(2004)]}. Accordingly, each particle of the system behaves like an independent

entity represented by a {\it macro-orbital}, -a kind of pair waveform identical

to that of a pair of particles moving with ($q$, $-q$) momenta at their {\it

center of mass} which may have any momentum $K$ in the laboratory frame. It

concludes: (i) $<A\delta{(x)}> = 0$, (ii) $<x> \ge \lambda/2$ and (iii) $q \ge

q_o (= \pi/d)$ (with $d = L/N$ being the average nearest neighbour distance),

{\it etc.} While all bosons in their ground state have $q = q_o$ and $K = 0$,

fermions have $q= q_o$ with different $K$ ranging between 0 and $K = K_F$ (the

Fermi wave vector). Independent of their bosonic or fermionic nature, all

particles in the ground state define a close packed arrangement of their equal

size wave packets representing an ordered state in phase ($\phi-$)space with

$\Delta\phi = 2n\pi$ (with $n$ = 1,2,3, ...), $<x> = \lambda/2 = d$, and $q =

q_o$. As such our approach uses greatly simplified mathematical formulation and

renders a visibly clear picture of the low energy states of the systems and its

results supplement earlier studies in providing their complete understanding.

\\ ( http://arXiv.org/abs/cond-mat/0606409 , 20kb)

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\\

Paper: cond-mat/0606416

Date: Thu, 15 Jun 2006 15:21:53 GMT (591kb)

Title: Mixing of ultracold atomic clouds by merging of two magnetic traps

Authors: Jesper Fevre Bertelsen, Henrik Kjaer Andersen, Sune Mai, and Michael

Budde

Subj-class: Other

\\

We demonstrate a new method to make mixtures of ultracold atoms which avoids

the two-species magneto-optical trap. We prepare two clouds of $^{87}$Rb atoms

in distinct magnetic quadrupole traps and mix the two clouds by merging the

traps. For correctly chosen parameters the mixing can be done essentially

without loss of atoms and with only minor heating. The basic features of the

process can be accounted for by a classical simulation of particle

trajectories. Such calculations indicate that mixing of different mass species

is also feasible, opening the way for using the method as a starting point for

making quantum gas mixtures.

\\ ( http://arXiv.org/abs/cond-mat/0606416 , 591kb)

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\\

Paper (*cross-listing*): math-ph/0606026

Date: Thu, 8 Jun 2006 13:06:10 GMT (18kb)

Title: The Functional Integration and the Two-Point Correlation Functions of

the Trapped Bose Gas

Authors: C. Malyshev, N. M. Bogoliubov

Comments: Extended version of the talk at The 8th International Conference

``Path Integrals from Quantum Information to Cosmology'' (Prague, June 6-10,

2005)

Subj-class: Mathematical Physics; Statistical Mechanics; Exactly Solvable and

Integrable Systems

MSC-class: 81S40; 42C10

\\

A quantum field-theoretical model, which describes spatially non-homogeneous

repulsive Bose gas in an external harmonic potential is considered. Two-point

thermal correlation functions of the Bose gas are calculated in the framework

of the functional integration approach. Successive integration over the

``high-energy'' functional variables first and then over the ``low-energy''

ones is used. The effective action functional for the low-energy variables is

obtained in one loop approximation. The functional integral representations for

the correlation functions are estimated by means of the stationary phase

approximation. A power-law asymptotical behaviour of the correlators of the

one-dimensional Bose gas is demonstrated in the limit, when the temperature is

going to zero, while the volume occupied by the non-homogeneous Bose gas

infinitely increases. The power-law behaviour is governed by the critical

exponent dependent on the spatial arguments.

\\ ( http://arXiv.org/abs/math-ph/0606026 , 18kb)

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\\

Paper (*cross-listing*): hep-th/0510238

replaced with revised version Thu, 15 Jun 2006 19:11:15 GMT (10kb)

Title: Casimir forces in Bose-Einstein condensates: finite size effects in

three-dimensional rectangular cavities

Authors: Ariel Edery

Comments: 12 pages; no figures; v.2: version accepted for publication in JSTAT

v.3: references added

Subj-class: High Energy Physics - Theory; Statistical Mechanics

Journal-ref: J. Stat. Mech. (2006) P06007

DOI: 10.1088/1742-5468/2006/06/P06007

\\ ( http://arXiv.org/abs/hep-th/0510238 , 10kb)

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\\

Paper: quant-ph/0606128

Date: Thu, 15 Jun 2006 02:20:53 GMT (230kb)

Title: How to observe a coherent superposition of an atom and a molecule

Authors: Mark R. Dowling, Stephen D. Bartlett, Terry Rudolph, and Robert W.

Spekkens

Comments: 17 pages, 1 figure, comments welcome

\\

We demonstrate that it is possible, in principle, to perform a Ramsey-type

interference experiment to exhibit a coherent superposition of a single atom

and a diatomic molecule. This gedanken experiment, based on the techniques of

Aharonov and Susskind [Phys. Rev. 155, 1428 (1967)], explicitly violates the

commonly-accepted superselection rule that forbids coherent superpositions of

eigenstates of differing atom number. This interference experiment makes use of

a Bose-Einstein condensate as a reference frame with which to perform the

coherent operations analogous to Ramsey pulses. We also investigate an

analogous gedanken experiment to exhibit a coherent superposition of a single

boson and a fermion, violating the commonly-accepted superselection rule

forbidding coherent superpositions of states of differing particle statistics;

in this case, the reference frame is realized by a multi-mode state of many

fermions. This latter case reproduces all of the relevant features of Ramsey

interferometry, including Ramsey fringes over many repetitions of the

experiment. However, the apparent inability of this proposed experiment to

produce well-defined relative phases between two distinct systems each

described by a coherent superposition of a boson and a fermion demonstrates

that there are additional, outstanding requirements to fully ``lift'' the

univalence superselection rule.

\\ ( http://arXiv.org/abs/quant-ph/0606128 , 230kb)

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\\

Paper: cond-mat/0606430

Date: Thu, 15 Jun 2006 21:22:01 GMT (741kb)

Title: Continuous and Pulsed Quantum Zeno Effect

Authors: Erik W. Streed, Jongchul Mun, Micah Boyd, Gretchen K. Campbell,

Patrick Medley, Wolfgang Ketterle, David E. Pritchard

Comments: 5 pages, 4 figures

Subj-class: Other

\\

Continuous and pulsed quantum Zeno effects were observed using a $^{87}$Rb

Bose-Einstein condensate(BEC). Oscillations between two ground hyperfine states

of a magnetically trapped condensate, externally driven at a transition rate

$\omega_R$, were suppressed by destructively measuring the population in one of

the states with resonant light. The suppression of the transition rate in the

two level system was quantified for pulsed measurements with a time interval

$\delta t$ between pulses and continuous measurements with a scattering rate

$\gamma$. We observe that the continuous measurements exhibit the same

suppression in the transition rate as the pulsed measurements when

$\gamma\delta t=3.60(0.43)$, in agreement with the predicted value of 4.

Increasing the measurement rate suppressed the transition rate down to

$0.005\omega_R$.

\\ ( http://arXiv.org/abs/cond-mat/0606430 , 741kb)

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\\

Paper: cond-mat/0606432

Date: Fri, 16 Jun 2006 00:39:20 GMT (694kb)

Title: Observation of Phase Separation in a Strongly-Interacting Imbalanced

Fermi Gas

Authors: Y. Shin, M. W. Zwierlein, C. H. Schunck, A. Schirotzek, W. Ketterle

Comments: 5 pages, 7 figures

Subj-class: Statistical Mechanics

\\

We have observed phase separation between the superfluid and the normal

component in a strongly interacting Fermi gas with imbalanced spin populations.

The in situ distribution of the density difference between two trapped spin

components is obtained using phase-contrast imaging and 3D image

reconstruction. A shell structure is clearly identified where the superfluid

region of equal densities is surrounded by a normal gas of unequal densities.

The phase transition induces a dramatic change in the density profiles as

excess fermions are expelled from the superfluid.

\\ ( http://arXiv.org/abs/cond-mat/0606432 , 694kb)

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\\

Paper: cond-mat/0601432

replaced with revised version Thu, 15 Jun 2006 21:38:02 GMT (439kb)

Title: Atomic matter of non-zero momentum Bose-Einstein condensation and

orbital current order

Authors: W. Vincent Liu and Congjun Wu

Comments: 10 pages, 7 figures (with one in Appendix); added references and

reorganized appendices in REVTeX

Subj-class: Other; Strongly Correlated Electrons

\\ ( http://arXiv.org/abs/cond-mat/0601432 , 439kb)

------------------------------------------------------------------------------

Till next week,

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 Tue Jun 20 2006 - 09:17:38 EST

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