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

Date: Wed, 25 Oct 2006 17:26:57 +1000 (EST)

Date: Wed, 25 Oct 2006 17:26:57 +1000 (EST)

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

Late again... but today I had my last 3 hours of teaching for 2006. So

from next week I should get back to Mondays for this email...

34 new papers this week.

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

The abstracts:

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Paper: cond-mat/0610364

Date: Fri, 13 Oct 2006 10:32:46 GMT (401kb)

Title: Dynamical Instabilities in a two-component Bose condensate in a 1d

optical lattice

Authors: Samantha Hooley and Keith A Benedict

Comments: 14 Pages, 9 figures

Subj-class: Other

\\

In this paper we carry out a stability analysis of the Bloch states of a

two-component Bose-Einstein condensate confined to a 1d optical lattice. We

consider two concrete systems: a mixture of two hyperfine states of Rubidium-87

and a mixture of Sodium-23 and Rubidium-87. The former is seen to exhibit

similar phenomena to a single component condensate while the latter also

suffers an instability to phase separation at small Bloch wave vectors. It is

shown that sufficiently deep optical lattices can remove this latter

instability, potentially allowing imiscible cold atoms species to be held in

intimate contact and transported within an experimental system.

\\ ( http://arXiv.org/abs/cond-mat/0610364 , 401kb)

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Paper: cond-mat/0610366

Date: Fri, 13 Oct 2006 11:02:39 GMT (13kb)

Title: Condition for the Existence of Complex Modes in a Trapped Bose--Einstein

Condensate with a Highly Quantized Vortex

Authors: Eriko Fukuyama, Makoto MIne, Masahiko Okumura, Tomoka Sunaga, Yoshiya

Yamanaka

Subj-class: Other

\\

We consider a trapped Bose--Einstein condensate (BEC) with a highly quantized

vortex. For the BEC with a doubly, triply or quadruply quantized vortex, the

numerical calculations have shown that the Bogoliubov--de Gennes equations,

which describe the fluctuation of the condensate, have complex eigenvalues. In

this paper, we obtain the analytic expression of the condition for the

existence of complex modes, using the method developed by Rossignoli and

Kowalski [R. Rossignoli and A. M. Kowalski, Phys. Rev. A 72, 032101 (2005)] for

the small coupling constant. To derive it, we make the two-mode approximation.

With the derived analytic formula, we can identify the quantum number of the

complex modes for each winding number of the vortex. Our result is consistent

with those obtained by the numerical calculation in the case that the winding

number is two, three or four. We prove that the complex modes always exist when

the condensate has a highly quantized vortex.

\\ ( http://arXiv.org/abs/cond-mat/0610366 , 13kb)

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Paper: cond-mat/0610367

Date: Fri, 13 Oct 2006 11:20:44 GMT (9kb)

Title: The depletion in Bose Einstein condensates using Quantum Field Theory in

curved space

Authors: Roberto Balbinot, Serena Fagnocchi, Alessandro Fabbri

Comments: 4 pages, no figure

Subj-class: Other

\\

Using methods developed in Quantum Field Theory in curved space we can

estimate the effects of the inhomogeneities and of a non vanishing flux on the

depletion of a Bose Einstein condensate within hydrodynamical approximation.

\\ ( http://arXiv.org/abs/cond-mat/0610367 , 9kb)

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Paper: cond-mat/0610380

Date: Fri, 13 Oct 2006 17:46:33 GMT (17kb)

Title: Ultracold heteronuclear molecules and ferroelectric superfluids

Authors: M. Iskin and C. A. R. Sa de Melo

Comments: 4 pages and 3 figures

Subj-class: Other; Superconductivity

\\

We analyze the possibility of a ferroelectric transition in heteronuclear

molecules consisting of Bose-Bose, Bose-Fermi or Fermi-Fermi atom pairs. This

transition is characterized by the appearance of a spontaneous electric

polarization below a critical temperature. We discuss the existence of a

ferroelectric Fermi liquid phase for Fermi molecules and the existence of a

ferroelectric superfluid phase for Bose molecules characterized by the

coexistence of ferroelectric and superfluid orders. Lastly, we propose an

experiment to detect ferroelectric correlations through the observation of

coherent dipole radiation pulses during time of flight.

\\ ( http://arXiv.org/abs/cond-mat/0610380 , 17kb)

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Paper: quant-ph/0610107

Date: Fri, 13 Oct 2006 17:46:14 GMT (610kb)

Title: Non-destructive interferometric characterization of an optical dipole

trap

Authors: Plamen G. Petrov, Daniel Oblak, Carlos L. Garrido Alzar, Niels

Kjaergaard, and Eugene S. Polzik

Comments: 9 pages, 6 figures, submitted to PRA

\\

A method for non-destructive characterization of a dipole trapped atomic

sample is presented. It relies on a measurement of the phase-shift imposed by

cold atoms on an optical pulse that propagates through a free space

Mach-Zehnder interferometer. Using this technique we are able to determine,

with very good accuracy, relevant trap parameters such as the atomic sample

temperature, trap oscillation frequencies and loss rates. Another important

feature is that our method is faster than conventional absorption or

fluorescence techniques, allowing the combination of high-dynamical range

measurements and a reduced number of spontaneous emission events per atom.

\\ ( http://arXiv.org/abs/quant-ph/0610107 , 610kb)

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Paper: physics/0610096

Date: Fri, 13 Oct 2006 01:06:40 GMT (336kb)

Title: Optical atomic coherence at the one-second time scale

Authors: Martin M. Boyd, Tanya Zelevinsky, Andrew D. Ludlow, Seth M. Foreman,

Sebastian Blatt, Tetsuya Ido, and Jun Ye

Comments: in press (2006)

Subj-class: Atomic Physics; Optics

\\

Highest resolution laser spectroscopy has generally been limited to single

trapped ion systems due to rapid decoherence which plagues neutral atom

ensembles. Here, precision spectroscopy of ultracold neutral atoms confined in

a trapping potential shows superior optical coherence without any deleterious

effects from motional degrees of freedom, revealing optical resonance

linewidths at the hertz level with an excellent signal to noise ratio. The

resonance quality factor of 2.4 x 10^{14} is the highest ever recovered in any

form of coherent spectroscopy. The spectral resolution permits direct

observation of the breaking of nuclear spin degeneracy for the 1S0 and 3P0

optical clock states of 87Sr under a small magnetic bias field. This optical

NMR-like approach allows an accurate measurement of the differential Lande

g-factor between the two states. The optical atomic coherence demonstrated for

collective excitation of a large number of atoms will have a strong impact on

quantum measurement and precision frequency metrology.

\\ ( http://arXiv.org/abs/physics/0610096 , 336kb)

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Paper: physics/0610098

Date: Fri, 13 Oct 2006 02:01:43 GMT (145kb)

Title: Dynamic cancellation of ac Stark shift for pulsed EIT/Raman optical

lattice clocks

Authors: T. Zanon-Willette, A.D. Ludlow, S. Blatt, M.M. Boyd, E. Arimondo,* Jun

Ye

Comments: submitted to Physical Review Letters

Subj-class: Atomic Physics; Optics

\\

We propose a combination of Electromagnetically Induced Transparency

(EIT)/Raman and pulsed spectroscopy techniques to accurately cancel frequency

shifts arising from EIT fields in forbidden optical lattice clock transitions

of alkaline earth atoms. Time-separated laser pulses are designed to trap atoms

in coherent superpositions while eliminating off-resonance ac Stark

contributions at particular laser detunings from the intermediate excited

state. The scheme achieves efficient population transfer up to 60% with

potential inaccuracy $<$ $10^{-17}$. Cancellation of external light shifts

determined by a density matrix approach is confirmed by a complex wave-function

formalism, sufficient at the mHz accuracy, under low field strengths or short

interaction times.

\\ ( http://arXiv.org/abs/physics/0610098 , 144kb)

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Paper: cond-mat/0610389

Date: Mon, 16 Oct 2006 06:37:23 GMT (198kb)

Title: Ultracold Bose Gases in 1D Random Potentials: From Lifshits Glasses to

Bose-Einstein Condensates

Authors: Pierre Lugan (LCFIO), David Cl\'{e}ment (LCFIO), Philippe Bouyer

(LCFIO), Alain Aspect (LCFIO), Maciej Lewenstein (ICFO), Laurent

Sanchez-Palencia (LCFIO)

Comments: 4 pages; 3 figures; minor reformulations compared to version 1

Proxy: ccsd ccsd-00106356

Subj-class: Other

\\

We study an ultracold Bose gas in the presence of 1D disorder for repulsive

inter-atomic interactions, ranging from zero to the Thomas-Fermi regime. We

show that for very small interactions, the Bose gas populates a finite number

of localized single particle Lifshits states, while for large interactions, it

forms a delocalized disordered Bose-Einstein condensate. We discuss the phase

diagram and compute the equations of state in various phases.

\\ ( http://arXiv.org/abs/cond-mat/0610389 , 198kb)

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Paper: cond-mat/0610400

Date: Sun, 15 Oct 2006 14:02:31 GMT (146kb)

Title: Thermodynamics of ideal quantum gas with fractional statistics in D

dimensions

Authors: Geoffrey G. Potter and Gerhard Muller and Michael Karbach

Comments: 15 pages, 31 figures

Subj-class: Statistical Mechanics; Disordered Systems and Neural Networks

\\

We present exact and explicit results for the thermodynamic properties

(isochores, isotherms, isobars, response functions, velocity of sound) of a

quantum gas in dimensions D>=1 and with fractional exclusion statistics 0<=g<=1

connecting bosons (g=0) and fermions (g=1). In D=1 the results are equivalent

to those of the Calogero-Sutherland model. Emphasis is given to the crossover

between boson-like and fermion-like features, caused by aspects of the

statistical interaction that mimic long-range attraction and short-range

repulsion. The full isochoric heat capacity and the leading low-T term of the

isobaric expansivity in D=2 are independent of g. The onset of Bose-Einstein

condensation along the isobar occurs at a nonzero transition temperature in all

dimensions. The T-dependence of the velocity of sound is in simple relation to

isochores and isobars. The effects of soft container walls are accounted for

rigorously for the case of a pure power-law potential.

\\ ( http://arXiv.org/abs/cond-mat/0610400 , 146kb)

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Paper: cond-mat/0610402

Date: Sun, 15 Oct 2006 17:03:41 GMT (92kb)

Title: Entanglement properties and moment distributions of a system of

hard-core anyons on a ring

Authors: Raoul Santachiara, Franck Stauffer and Daniel Cabra

Comments: 5 pages, 3 eps figures

Subj-class: Strongly Correlated Electrons; Mesoscopic Systems and Quantum Hall

Effect

\\

We study the one-particle von Neumann entropy of a system of N hard-core

anyons on a ring. The entropy is found to have a clear dependence on the

anyonic parameter which characterizes the generalized fractional statistics

described by the anyons. This confirms the entanglement as a valuable measure

to investigate topological properties of quantum states. Furthermore, we

determine analytically the large N asymptotics of the anyonic one-particle

density matrix. The formula presented here generalizes the Lenard formula

obtained for a system of N hard-core bosons. Finally, we present a numerical

analysis which confirms the analytical results and provides additional insight

into the problem under consideration.

\\ ( http://arXiv.org/abs/cond-mat/0610402 , 92kb)

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Paper: cond-mat/0610411

Date: Mon, 16 Oct 2006 08:34:03 GMT (10kb)

Title: Level Density of a Bose Gas and Extreme Value Statistics

Authors: A. Comtet, P. Leboeuf, Satya N. Majumdar

Comments: 4 pages, no figures

Subj-class: Statistical Mechanics

\\

We establish a connection between the level density of a gas of

non-interacting bosons and the theory of extreme value statistics. Depending on

the exponent that characterizes the growth of the underlying single-particle

spectrum, we show that at a given excitation energy the limiting distribution

function for the number of excited particles follows the three universal

distribution laws of extreme value statistics, namely Gumbel, Weibull and

Fr\'echet. Implications of this result, as well as general properties of the

level density at different energies, are discussed.

\\ ( http://arXiv.org/abs/cond-mat/0610411 , 10kb)

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Paper: cond-mat/0610412

Date: Mon, 16 Oct 2006 08:51:38 GMT (7kb)

Title: Bose-Einstein condensation temperature of a gas of weakly dissociated

diatomic molecules

Authors: L. M. Jensen, H. M\"akel\"a and C. J. Pethick

Comments: 4 pages

Report-no: NORDITA-2006-35

Subj-class: Other; Superconductivity

\\

We consider the properties of a gas of bosonic diatomic molecules in the

limit when few of the molecules are dissociated. Taking into account the

effects of dissociation and scattering among molecules and atoms, we calculate

the dispersion relation for a molecule, and the thermal depletion of the

condensate. We calculate the dependence of the Bose-Einstein condensation

temperature of a uniform gas on the atom-atom scattering length, and conclude

that, for a broad Feshbach resonance, the condensation temperature increases as

the molecular state becomes less strongly bound, thereby giving rise to a

maximum in the transition temperature in the BEC-BCS crossover. We also argue

on general grounds that, for a gas in a harmonic trap and for a narrow Feshbach

resonance, the condensation temperature will decrease with increasing

scattering length.

\\ ( http://arXiv.org/abs/cond-mat/0610412 , 7kb)

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Paper: cond-mat/0610414

Date: Mon, 16 Oct 2006 09:00:15 GMT (245kb)

Title: Production of a degenerate Fermi gas of metastable helium-3 atoms

Authors: W. Vassen, T. Jeltes, J.M. McNamara and A.S. Tychkov

Comments: 18 pages, 11 figures; to be published in the Proceedings of the

International school of physics "Enrico Ferm": Ultracold Fermi gases,

Varenna, June 20-30 (2006)

Subj-class: Other

\\

We give an overview of the experiments at the Laser Centre of the Vrije

Universiteit in Amsterdam on ultracold gases of metastable helium-4 and

helium-3 as well as mixtures of both isotopes. We describe our experimental

setup and discuss our experiments on Bose-Einstein condensation of 4He* (more

than 10 million atoms in a BEC) and sympathetic cooling of 3He* towards Fermi

degeneracy (more than 1 million atoms below the Fermi temperature as well as

realization of a degenerate boson-fermion mixture). We also present our results

on Penning Ionization in ~1 mK clouds containing a single isotope (homonuclear

losses) or a mixture of both isotopes (heteronuclear losses).

\\ ( http://arXiv.org/abs/cond-mat/0610414 , 245kb)

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Paper: cond-mat/0610420

Date: Mon, 16 Oct 2006 11:50:34 GMT (6kb)

Title: Kelvin-wave turbulence generated by vortex reconnections

Authors: Sergey Nazarenko

Comments: To be submitted to JETP Letters

Subj-class: Other; Statistical Mechanics

\\

Reconnections of quantum vortex filaments create sharp bends which degenerate

into propagating Kelvin waves. These waves cascade their energy down-scale and

their waveaction up-scale via weakly nonlinear interactions, and this is the

main mechanism of turbulence at the scales less than the inter-vortex distance.

In case of an idealised forcing concentrated around a single scale k0, the

turbulence spectrum exponent has a pure direct cascade form -17/5 at scales

k>k0 and a pure inverse cascade form -3 at k<k0. However, forcing produced by

the reconnections contains a broad range of Fourier modes. What scaling should

one expect in this case? In this Letter I obtain an answer to this question

using the differential model for the Kelvin wave turbulence. The main result is

that the direct cascade scaling dominates, i.e. the reconnection forcing is

more or less equivalent to a low-frequency forcing.

\\ ( http://arXiv.org/abs/cond-mat/0610420 , 6kb)

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Paper: cond-mat/0610435

Date: Mon, 16 Oct 2006 15:10:53 GMT (15kb)

Title: Paired state in spinor bosons: from exact result to mean field approach

Authors: Junpeng Cao, Yuzhu Jiang, Yupeng Wang

Subj-class: Strongly Correlated Electrons

\\

An exactly solvable model describing the low density limit of the spinor

bosons in a one dimensional optical lattice is proposed. The exact Bethe ansatz

solution shows that the low energy physics of this system is described by a

quantum liquid of spin singlet bound pairs. Motivated by the exact results, a

mean-field approach to the corresponding three-dimensional system is carried

out. Condensation of singlet pairs and coexistence with ordinary Bose-Einstein

condensation are observed.

\\ ( http://arXiv.org/abs/cond-mat/0610435 , 15kb)

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Paper: cond-mat/0610437

Date: Mon, 16 Oct 2006 17:10:20 GMT (40kb)

Title: Attractive Fermi gases with unequal populations in higly elongated traps

Authors: G. Orso

Comments: 5 pages, 3 figures

Subj-class: Other; Superconductivity

\\

We investigate two-component attractive Fermi gases with density imbalance in

trapped quasi-1D configurations. The ground state properties are determined

within local density approximation, starting from the exact Bethe-ansatz

equations for the homogeneous case. We predict that the atoms are distributed

according to a two-shell structure with a partially polarized phase in the

center of the trap and either a fully paired or a fully polarized phase in the

wings. The size of the cloud as well as the critical polarization needed to

suppress the fully paired shell, are calculated as a function of the coupling

strength.

\\ ( http://arXiv.org/abs/cond-mat/0610437 , 40kb)

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Paper: quant-ph/0610114

Date: Mon, 16 Oct 2006 02:49:57 GMT (140kb)

Title: Rotation of quantum gases in a two dimensional lattice with a harmonic

trap

Authors: T. Wang, S. Yelin

Comments: 4 pages

\\

Rotation of gases in a lattice is studied with the Hubbard model. It is found

that the gases do not fly away when the rotation frequency is slightly greater

than the trapping frequency, which is very different from the behavior in

continuum. The Bragg scattering and the coupling between the angular motion and

the radial motion make the above stability possible. In this regime, density

depletion at the center of the trap can be developed for spin polarized

fermions.

\\ ( http://arXiv.org/abs/quant-ph/0610114 , 140kb)

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Paper: quant-ph/0610117

Date: Sat, 14 Oct 2006 15:07:17 GMT (36kb)

Title: Is Fault-Tolerant Quantum Computation Really Possible?

Authors: M. I. Dyakonov

Comments: Based on a talk given at the Future Trends in Microelectronics

workshop, Crete, June 2006. 8 pages, 1 figure

\\

The so-called "threshold" theorem says that, once the error rate per qubit

per gate is below a certain value, indefinitely long quantum computation

becomes feasible, even if all of the qubits involved are subject to relaxation

processes, and all the manipulations with qubits are not exact. The purpose of

this article, intended for physicists, is to outline the ideas of quantum error

correction and to take a look at the proposed technical instruction for

fault-tolerant quantum computation. It seems that the mathematics behind the

threshold theorem is somewhat detached from the physical reality, and that some

ideal elements are always present in the construction. This raises serious

doubts about the possibility of large scale quantum computations, even as a

matter of principle.

\\ ( http://arXiv.org/abs/quant-ph/0610117 , 36kb)

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Paper: cond-mat/0610445

Date: Mon, 16 Oct 2006 22:44:06 GMT (466kb)

Title: Quantum Scattering of Distinguishable Bosons using an Ultracold Atom

Collider

Authors: Angela S. Mellish, Niels Kjaergaard, Paul S. Julienne, and Andrew C.

Wilson

Subj-class: Other

\\

We describe a new implementation of magnetic collider for investigating cold

collisions between ultracold atomic clouds in different spin states, and we use

this to investigate scattering involving both even and odd order partial waves.

Our method relies on the axial assymetry of a double-well magnetic trap to

selectively prepare the spin state in each cloud. We measure the energy

dependence of s, p and d partial wave phase shifts in collisions up to 300

microKelvin between ^{87}Rb atoms in the 5S_{1/2}, F=1, m_F=-1 and 5S_{1/2},

F=2, m_F=1 states.

\\ ( http://arXiv.org/abs/cond-mat/0610445 , 466kb)

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Paper: cond-mat/0610448

Date: Tue, 17 Oct 2006 10:32:44 GMT (259kb)

Title: FFLO phase in one-dimensional polarized Fermi gases

Authors: Hui Hu, Xia-Ji Liu, and Peter D. Drummond

Comments: 4 pages, 5 figures

Subj-class: Superconductivity; Statistical Mechanics

\\

Based on the integrable Gaudin model and local density approximation, we

discuss the phase structure of one-dimensional trapped Fermi gases with

imbalanced spin populations for arbitrary attractive interactions. A phase

separation state, with a polarized superfluid core immersed in an unpolarized

superfluid shell, emerges below a critical spin polarization. Above it, a

coexistence of polarized superfluid matter and a fully polarized normal gas is

favored. These two exotic states could be realized experimentally in highly

elongated atomic traps, and diagnosed by measuring the lowest density

compressional mode. We identify the polarized superfluid as having an FFLO

structure, and predict the resulting mode frequency as a function of the spin

polarization.

\\ ( http://arXiv.org/abs/cond-mat/0610448 , 259kb)

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Paper: cond-mat/0610476

Date: Tue, 17 Oct 2006 14:42:40 GMT (207kb)

Title: Mean-field phase diagram of cold lattice bosons in disordered potentials

Authors: P. Buonsante, V. Penna, A. Vezzani and P.B. Blakie

Comments: 5 pages, 4 figures

Subj-class: Soft Condensed Matter; Statistical Mechanics

\\

We show that a site-dependent mean-field approach captures the quantum phases

of the disordered Bose-Hubbard model commonly adopted to describe ultracold

bosons in random optical lattice potentials. The different phases, namely

superfluid, Mott insulator, Bose-glass and -- at finite temperature -- normal

fluid, are characterized by means of the superfluid and condensate fractions,

and compressibility of the system. We point out that both the boundaries of the

Mott lobes and the nature of the phase surrounding them are related to the

spectral features of a purely off-diagonal non-interacting Anderson model. We

compare our results to other works.

\\ ( http://arXiv.org/abs/cond-mat/0610476 , 207kb)

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Paper: cond-mat/0610485

Date: Tue, 17 Oct 2006 18:56:07 GMT (233kb)

Title: Vortices and phase transitions of interacting bosons in a rotating

lattice ring

Authors: Qi Zhou

Comments: 4 pages, 3 figures

Subj-class: Other

\\

We investigate the ground state properties of the repulsive interacting

bosons in an one dimensional rotating lattice ring, and reveal that the

superfluid density of the system and the mass current it can carry in the

rotating coordinate are periodic functions of the velocity of the lattice. In

the weakly interacting limit, the vortices are generated at the critical

velocities, and in the strongly interacting limit, the phase twist of the

bosons induced by the rotating lattice manifests the superfluid density and

drive the system to undergo phase transitions between the superfluid and Mott

insulator.

\\ ( http://arXiv.org/abs/cond-mat/0610485 , 233kb)

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Paper: quant-ph/0610135

Date: Tue, 17 Oct 2006 09:59:37 GMT (12kb)

Title: Majorana spin-flip transitions in a magnetic trap

Authors: D.M.Brink and C.V.Sukumar

Comments: 16pages

\\

Atoms confined in a magnetic trap can escape by making spin-flip Majorana

transitions due to a breakdown of the adiabatic approximation. Several papers

have studied this process for atoms with spin $F = 1/2$ or $F= 1$. The present

paper calculates the escape rate for atoms with spin $F > 1$. This problem has

new features because the perturbation $\Delta T$ which allows atoms to escape

satisfies a selection rule $\Delta F_z = 0, \pm 1, \pm 2$ and multi-step

processes contribute in leading order. When the adiabatic approximation is

satisfied the leading order terms can be summed to yield a simple expression

for the escape rate.

\\ ( http://arXiv.org/abs/quant-ph/0610135 , 12kb)

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Paper: quant-ph/0610136

Date: Tue, 17 Oct 2006 10:28:32 GMT (380kb)

Title: Optical Nanofibers for Manipulating and Probing Single-Atom Fluorescence

Authors: K. P. Nayak, P. N. Melentiev, M. Morinaga, Fam Le Kien, V. I. Balykin,

and K. Hakuta

\\

We demonstrate how optical nanofibers can be used to manipulate and probe

single-atom fluorescence. We show that fluorescence photons from a very small

number of atoms, average atom number of less than 0.1, around the nanofiber can

readily be observed through single-mode optical fiber under resonant laser

irradiation. We show also that optical nanofibers enable us to probe the van

der Waals interaction between atoms and surface with high precision by

observing the fluorescence excitation spectrum.

\\ ( http://arXiv.org/abs/quant-ph/0610136 , 380kb)

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Paper: quant-ph/0610141

Date: Tue, 17 Oct 2006 16:04:58 GMT (156kb)

Title: High-temperature Bose-Einstein condensation of polaritons: realization

under the intracavity laser pumping of matter condition

Authors: V. A. Averchenko, A. P. Alodjants, S. M. Arakelian, S. N. Bagayev, E.

A. Vinogradov, V. S. Egorov, A. I. Stolyarov, I. A. Chekhonin

Comments: 9 pages, PDF only

Journal-ref: Kvantovaya Elektronika (Quantum Elactronics), V.36 (2006)

pp.532-538

\\

A quantum model of Bose-Einstein condensation based on processes involving

polaritons excited in an intracavity absorbing cell with resonance atoms, which

is manifested in the spectral characteristics of the system, is considered. It

is shown that the spectral 'condensation' appears which is directly related to

the degeneracy of a weakly interacting gas of polaritons resulting in

quasi-condensation at room temperature. The possibility of obtaining polariton

condensation as a new phase state by using the confinement of polaritons in an

atomic optical harmonic trap is discussed.

\\ ( http://arXiv.org/abs/quant-ph/0610141 , 156kb)

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Paper: physics/0610123

Date: Tue, 17 Oct 2006 11:18:51 GMT (52kb)

Title: Dissipative light field as a way to create strongly localized structures

for atom lithography

Authors: O.N. Prudnikov, A.V. Taichenachev, A.M. Tumaikin, V.I. Yudin

Comments: 4 figures

Subj-class: Atomic Physics

\\

Generally, the conditions for deep sub-Doppler laser cooling do not match the

conditions for the strong atomic localization that takes a place in deeper

optical potential and, in consequence, leads to larger temperature. Moreover,

for a given detuning in a deep optical potential the secular approximation

which is usually used for quantum description of laser cooling becomes no more

valid. Here we perform an analysis of atomic localization in optical potential

based on a full quantum approach for atomic density matrix. We also show that

the laser cooling in a deep far-off detuned optical potential, created by a

light field with a polarization gradient, can be used as an alternative method

for forming high contrast spatially localized structures of atoms for the

purposes of atom lithography and atomic nanofabrication. Finally, we perform an

analysis of the possible limits for the width and the contrast of localized

atomic structures that can in principle be reached by this type of the light

mask.

\\ ( http://arXiv.org/abs/physics/0610123 , 52kb)

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Paper: cond-mat/0610498

Date: Wed, 18 Oct 2006 07:46:25 GMT (105kb)

Title: Damagnetization cooling of a gas

Authors: M. Fattori, T. Koch, S. Goetz, A. Griesmaier, S. Hensler, J. Stuhler,

T. Pfau

Comments: 10 pages, 5 figures

Subj-class: Other

Journal-ref: Nature Physics, November 2006

\\

We demonstrate demagnetization cooling of a gas of ultracold $^{52}$Cr atoms.

Demagnetization is driven by inelastic dipolar collisions which couple the

motional degrees of freedom to the spin degree. By that kinetic energy is

converted into magnetic work with a consequent temperature reduction of the

gas. Optical pumping is used to magnetize the system and drive continuous

demagnetization cooling. Applying this technique, we can increase the phase

space density of our sample by one order of magnitude, with nearly no atom

loss. This method can be in principle extended to every dipolar system and

could be used to achieve quantum degeneracy via optical means.

\\ ( http://arXiv.org/abs/cond-mat/0610498 , 105kb)

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Paper: cond-mat/0610512

Date: Wed, 18 Oct 2006 14:54:29 GMT (396kb)

Title: Symmetry breaking in small rotating cloud of trapped ultracold Bose

atoms

Authors: D. Dagnino, N. Barber\'an, M. Lewenstein, K. Osterloh, and A. Riera

Comments: 4 pages, 2 figures

Subj-class: Mesoscopic Systems and Quantum Hall Effect

\\

We study the signatures of rotational and phase symmetry breaking in small

rotating clouds of trapped ultracold Bose atoms by looking at rigorously

defined condensate wave function. Rotational symmetry breaking occurs in narrow

frequency windows, where the ground state of the system has degenerated with

respect to the total angular momentum, and it leads to a complex wave function

that exhibits vortices clearly seen as holes in the density, as well as

characteristic vorticity. Phase symmetry (or gauge symmetry) breaking, on the

other hand, is clearly manifested in the interference of two independent

rotating clouds.

\\ ( http://arXiv.org/abs/cond-mat/0610512 , 396kb)

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Paper: quant-ph/0610149

Date: Wed, 18 Oct 2006 14:07:38 GMT (285kb)

Title: Quantum interference between two single photons emitted by independently

trapped atoms

Authors: Jerome Beugnon (LCFIO), Matthew Jones (LCFIO), Jos Dingjan (LCFIO),

Benoit Darqui\'{e} (LCFIO), Gaetan Messin (LCFIO), Antoine Browaeys (LCFIO),

Philippe Grangier (LCFIO)

Proxy: ccsd ccsd-00107420

Journal-ref: Nature 440 (06/04/2006) 779

\\

When two indistinguishable single photons are fed into the two input ports of

a beam splitter, the photons will coalesce and leave together from the same

output port. This is a quantum interference effect, which occurs because the

two possible paths where the photons leave in different output ports interfere

destructively. This effect was first observed in parametric downconversion by

Hong, Ou and Mandel, and then with single photons produced one after the other

by the same quantum emitter. With the recent development of quantum

information, a lot of attention has been devoted to this coalescence effect as

a resource for quantum data processing using linear optics techniques. To

ensure the scalability of schemes based on these ideas, it is crucial that

indistinguishable photons are emitted by a collection of synchronized, but

otherwise independent sources. In this paper, we demonstrate the quantum

interference of two single photons emitted by two independently trapped single

atoms, bridging the gap towards the simultaneous emission of many

indistinguishable single photons by different emitters. Our data analysis shows

that the coalescence observed is mostly limited by the wavefront matching of

the light emitted by the two atoms, and to a lesser extent by the motion of

each atom in its own trap.

\\ ( http://arXiv.org/abs/quant-ph/0610149 , 285kb)

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Paper: quant-ph/0610150

Date: Wed, 18 Oct 2006 15:53:02 GMT (268kb)

Title: Atom in a coherently controlled squeezed vacuum

Authors: Itay Rabinak, Eran Ginossar and Shimon Levit

Comments: 4 pages, 4 figures

\\

A broadband squeezed vacuum photon field is characterized by a complex

squeezing function. We show that by controlling the wavelength dependence of

its phase it is possible to change the dynamics of the atomic polarization

interacting with the squeezed vacuum. Such a phase modulation effectively

produces a finite range temporal interaction kernel between the two quadratures

of the atomic polarization yielding the change in the decay rates as well as

the appearance of additional oscillation frequencies. We show that decay rates

slower than the spontaneous decay rate can be achieved even for a squeezed bath

in the classic regime. For linear and quadratic phase modulations the power

spectrum of the scattered light exhibits narrowing of the central peak due to

the modified decay rates. For strong phase modulations side lobes appear

symmetrically around the central peak reflecting additional oscillation

frequencies.

\\ ( http://arXiv.org/abs/quant-ph/0610150 , 268kb)

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Paper: physics/0610131

Date: Tue, 17 Oct 2006 23:40:23 GMT (156kb)

Title: Cold Atomic Collisions: Coherent Control of Penning and Associative

Ionization

Authors: Carlos A. Arango, Moshe Shapiro, and Paul Brumer

Comments: 4 pages, 2 tables, 2 figures

Subj-class: Chemical Physics; Atomic Physics

\\

Coherent Control techniques are computationally applied to cold (1mK < T < 1

K) and ultracold (T < 1 microK) Ne*(3s,3P2) + Ar(1S0) collisions. We show that

by using various initial superpositions of the Ne*(3s,3P2) M = {-2,-1,0,1,2}

Zeeman sub-levels it is possible to reduce the Penning Ionization (PI) and

Associative Ionization (AI) cross sections by as much as four orders of

magnitude. It is also possible to drastically change the ratio of these two

processes. The results are based on combining, within the "Rotating Atom

Approximation", empirical and ab-initio ionization-widths.

\\ ( http://arXiv.org/abs/physics/0610131 , 156kb)

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Paper: cond-mat/0610532

Date: Thu, 19 Oct 2006 08:57:27 GMT (129kb)

Title: Dynamical Instability in a Trimeric Chain of Interacting Bose-Einstein

Condensates

Authors: P. Buonsante, R. Franzosi, and V. Penna

Comments: 5 pages, 3 figures

Subj-class: Other

Journal-ref: Phys. Rev Lett. 90 (2003) 050404

DOI: 10.1103/PhysRevLett.90.050404

\\

We analyze thoroughly the mean-field dynamics of a linear chain of three

coupled Bose-Einstein condensates, where both the tunneling and the

central-well relative depth are adjustable parameters. Owing to its

nonintegrability, entailing a complex dynamics with chaos occurrence, this

system is a paradigm for longer arrays whose simplicity still allows a thorough

analytical study.We identify the set of dynamics fixed points, along with the

associated proper modes, and establish their stability character depending on

the significant parameters. As an example of the remarkable operational value

of our analysis, we point out some macroscopic effects that seem viable to

experiments.

\\ ( http://arXiv.org/abs/cond-mat/0610532 , 129kb)

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Paper: cond-mat/0610536

Date: Thu, 19 Oct 2006 12:38:27 GMT (21kb)

Title: Bose-Einstein condensation of magnons in ferromagnets with easy-plane

anisotropy and in antiferromagnets with weakly coupled ferromagnetic plains

or chains

Authors: A. V. Syromyatnikov

Comments: 5 pages, 1 figure, submitted to PRB

Subj-class: Strongly Correlated Electrons

\\

Bose-Einstein condensation of magnons (BEC) in antiferromagnets (AFs) is

attracted much attention now. In the present paper we discuss BEC in two

classes of magnets that have not been considered before: easy-plane

ferromagnets and AFs containing weakly coupled ferromagnetic plains or chains.

We show that in these magnets the point $H=H_c$ is a quantum critical point

belonging to BEC universality class, where $H$ is the transverse magnetic field

and $H_c$ is its saturation value. Magnetic materials of these types are

promising candidates for experimental investigation of BEC because they have

small saturation fields.

\\ ( http://arXiv.org/abs/cond-mat/0610536 , 21kb)

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Paper (*cross-listing*): math-ph/0610034

Date: Mon, 16 Oct 2006 17:31:44 GMT (12kb)

Title: Bose-Einstein Condensation and Spontaneous Symmetry Breaking

Authors: Elliott H. Lieb, Robert Seiringer, Jakob Yngvason

Comments: Contribution to the proceedings of the 21st Max Born Symposium,

Wroclaw, Poland, June 26--28, 2006

Subj-class: Mathematical Physics; Statistical Mechanics

\\

After recalling briefly the connection between spontaneous symmetry breaking

and off-diagonal long range order for models of magnets a general proof of

spontaneous breaking of gauge symmetry as a consequence of Bose-Einstein

Condensation is presented. The proof is based on a rigorous validation of

Bogoliubov's $c$-number substitution for the ${\bf k}={\bf 0}$ mode operator

$a_{\bf 0}$.

\\ ( http://arXiv.org/abs/math-ph/0610034 , 12kb)

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Paper: cond-mat/0601500

replaced with revised version Thu, 12 Oct 2006 20:38:44 GMT (18kb)

Title: Thermodynamically activated vortex-dipole formation in a two-dimensional

Bose-Einstein condensate

Authors: Daniel Schumayer and David A. W. Hutchinson

Comments: 5 pages, 3 figures v2: restructured and minor corrections were made

Subj-class: Statistical Mechanics

\\ ( http://arXiv.org/abs/cond-mat/0601500 , 18kb)

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Paper: quant-ph/0601079

replaced with revised version Fri, 13 Oct 2006 01:16:10 GMT (164kb)

Title: Entanglement of indistinguishable particles in condensed matter physics

Authors: Mark R. Dowling, Andrew C. Doherty and Howard M. Wiseman

Comments: 13 pages, 6 figures, comments welcome, published version (minor

changes, added references)

Journal-ref: Phys. Rev. A, 73, 052323 (2006)

\\ ( http://arXiv.org/abs/quant-ph/0601079 , 164kb)

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Paper: physics/0412124

replaced with revised version Fri, 13 Oct 2006 15:27:55 GMT (366kb)

Title: Measurement method for the nuclear anapole moment of laser trapped

alkali atoms

Authors: E. Gomez (1), S. Aubin (1 and 2), G. D. Sprouse (1), L. A. Orozco (3),

D. P. DeMille (4) ((1) Dept. of Physics and Astronomy, State University of

New York at Stony Brook, NY, U.S.A., (2) Dept. of Physics, University of

Toronto, Ontario, Canada, (3) Dept. of Physics, University of Maryland,

College Park, MD, U.S.A., (4) Dept. of Physics, Yale University, New Haven,

CT, U.S.A.)

Comments: 12 pages, 4 figures

Subj-class: Atomic Physics

\\ ( http://arXiv.org/abs/physics/0412124 , 366kb)

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Paper: cond-mat/0506293

replaced with revised version Sun, 15 Oct 2006 01:33:34 GMT (57kb)

Title: A new many-body wave function for BCS-BEC crossover in Fermi gases

Authors: Shina Tan and K. Levin

Comments: 5 pages, 2 color figures

Subj-class: Statistical Mechanics

Journal-ref: Phys. Rev. A 74, 043606 (2006)

\\ ( http://arXiv.org/abs/cond-mat/0506293 , 57kb)

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Paper: cond-mat/0608673

replaced with revised version Sat, 14 Oct 2006 13:10:22 GMT (369kb)

Title: Spin-quadrupole ordering of spin-3/2 ultracold fermionic atoms in

optical lattices in the one-band Hubbard model

Authors: Hong-Hao Tu, Guang-Ming Zhang, Lu Yu

Comments: 12 pages, 4 figures

Subj-class: Strongly Correlated Electrons

Journal-ref: Phys. Rev. B 74, 037641 (2006)

\\ ( http://arXiv.org/abs/cond-mat/0608673 , 369kb)

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Paper (*cross-listing*): math-ph/0510006

replaced with revised version Mon, 16 Oct 2006 17:51:59 GMT (31kb)

Title: Bosons in Disc-Shaped Traps: From 3D to 2D

Authors: K. Schnee, J. Yngvason

Comments: Corrected version. To be published in Communications in Mathematical

Physics

Subj-class: Mathematical Physics; Statistical Mechanics

\\ ( http://arXiv.org/abs/math-ph/0510006 , 31kb)

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Paper: physics/0604008

replaced with revised version Mon, 16 Oct 2006 08:20:22 GMT (359kb)

Title: Anomalous translational velocity of vortex ring with finite-amplitude

Kelvin waves

Authors: C.F. Barenghi, R. H\"anninen, M. Tsubota

Comments: 6 pages, 5 figures, v2: minor changes, v3: typos corrected

Subj-class: Fluid Dynamics; Soft Condensed Matter

Journal-ref: Phys. Rev. E 74, 046303 (2006)

DOI: 10.1103/PhysRevE.74.046303

\\ ( http://arXiv.org/abs/physics/0604008 , 359kb)

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Paper: cond-mat/0601650

replaced with revised version Mon, 16 Oct 2006 21:15:28 GMT (33kb)

Title: Dynamics of the Bose-Hubbard model: transition from Mott insulator to

superfluid

Authors: Fernando M. Cucchietti, Bogdan Damski, Jacek Dziarmaga, and Wojciech

H. Zurek

Comments: 7+ pages, the Bogolubov section is completely rewritten

Report-no: LAUR-06-0477

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0601650 , 33kb)

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Paper: cond-mat/0604086

replaced with revised version Tue, 17 Oct 2006 17:39:45 GMT (331kb)

Title: Bright Matter-Wave Soliton Collisions in a Harmonic Trap: Regular and

Chaotic Dynamics

Authors: A. D. Martin, C. S. Adams and S. A. Gardiner

Comments: 4 pages, 3 figures, content changed in response to referee comments,

references added

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0604086 , 331kb)

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Paper: cond-mat/0609337

replaced with revised version Wed, 18 Oct 2006 01:35:47 GMT (388kb)

Title: Quantum Entanglement Manifestation of Transition to Nonlinear

Self-trapping for Bose-Einstein Condensates in a Symmetric Double-Well

Authors: Li-Bin Fu and Jie Liu

Comments: 6 pages, 5 figures

Subj-class: Mesoscopic Systems and Quantum Hall Effect

\\ ( http://arXiv.org/abs/cond-mat/0609337 , 388kb)

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Paper: cond-mat/0610345

replaced with revised version Wed, 18 Oct 2006 08:27:14 GMT (38kb)

Title: Collective mode description for a clean Fermi gas with repulsion in

arbitrary dimensions: interaction of spin excitations and its consequences

Authors: K.B. Efetov, I.L. Aleiner

Comments: A talk given at the conference "Mott's Physics in Nanowires and

Quantum Dots", Cambridge, UK, 2006; corrected typos

Subj-class: Strongly Correlated Electrons; Disordered Systems and Neural

Networks

\\ ( http://arXiv.org/abs/cond-mat/0610345 , 38kb)

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Paper: quant-ph/0604165

replaced with revised version Wed, 18 Oct 2006 04:04:08 GMT (113kb)

Title: Entanglement of orbital angular momentum states between an ensemble of

cold atoms and a photon

Authors: R. Inoue, N. Kanai, T. Yonehara, Y. Miyamoto, M. Koashi and M. Kozuma

Comments: 5 pages, 3 figures To appear in Physical Review A

\\ ( http://arXiv.org/abs/quant-ph/0604165 , 113kb)

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Paper: quant-ph/0605252

replaced with revised version Tue, 17 Oct 2006 20:39:02 GMT (740kb)

Title: Photoassociation adiabatic passage of ultracold Rb atoms to form

ultracold Rb_2 molecules

Authors: Evgeny A. Shapiro, Moshe Shapiro, Avi Pe'er, and Jun Ye

Comments: RevTex, 23 pages, 9 figures

\\ ( http://arXiv.org/abs/quant-ph/0605252 , 740kb)

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Paper: cond-mat/0607103

replaced with revised version Tue, 17 Oct 2006 02:46:25 GMT (49kb)

Title: Bose-Condensed Gases in a 1D Optical Lattice at Finite Temperatures

Authors: E. Arahata and T. Nikuni

Comments: Comments: 6 pages, 3 figures, submitted to Quantum Fluids and Solids

Conference (QFS 2006)

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0607103 , 49kb)

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Paper: cond-mat/0607179

replaced with revised version Tue, 17 Oct 2006 08:09:40 GMT (286kb)

Title: Visualization of vortex bound states in polarized Fermi gases at

unitarity

Authors: Hui Hu, Xia-Ji Liu, and Peter D. Drummond

Comments: 4 pages, and 4 figures

Subj-class: Superconductivity; Statistical Mechanics

\\ ( http://arXiv.org/abs/cond-mat/0607179 , 286kb)

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Paper: cond-mat/0607556

replaced with revised version Mon, 16 Oct 2006 23:13:04 GMT (22kb)

Title: Interferences in the density of two initially independent Bose-Einstein

condensates

Authors: L. S. Cederbaum, A. I. Streltsov, Y. B. Band, and O. E. Alon

Comments: 13 pages, 2 figures

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0607556 , 22kb)

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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/ ========================================================================= 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 Wed Oct 25 2006 - 17:26:57 EST

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