# Matt's arXiv selection, Tuesday 18th April 2006.

From: Matthew Davis <mdavis_at_physics.uq.edu.au>
Date: Tue, 18 Apr 2006 15:12:42 +1000 (EST)

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

Hi everyone,

This week's mailing is late due to the Easter Monday public holiday - but
to make up for it I have included all preprints up until the Tuesday
mailing that just arrived in my inbox.

The home page for this mailing list can be found here:

Feel free to put the link on your own website. Currently there are 217
subscribers. Also, if you have any feedback it is more than welcome!

Best regards,
Matt.

--
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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/
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Paper: cond-mat/0604186
Date: Thu, 6 Apr 2006 20:15:15 GMT   (19kb)
Title: BEC-BCS crossover in an optical lattice
Authors: A. O. Koetsier, D. B. M. Dickerscheid, H. T. C. Stoof
Comments: 4 pages, 3 figures
Subj-class: Statistical Mechanics
\\
We present the microscopic theory for the BEC-BCS crossover of an atomic
Fermi gas in an optical lattice, showing that the Feshbach resonance underlying
the crossover in principle induces strong multiband effects. Nevertheless, the
BEC-BCS crossover itself can be described by a single-band model since it
occurs at magnetic fields that are relatively far away from the Feshbach
resonance. A criterion is proposed for the latter, which is obeyed by most
known Feshbach resonances in ultracold atomic gases.
\\ ( http://arXiv.org/abs/cond-mat/0604186 ,  19kb)
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Paper: cond-mat/0601148
replaced with revised version Fri, 7 Apr 2006 19:48:22 GMT   (32kb)
Title: Finite Size Effects in Cold Asymmetrical Fermion Superfluids
Authors: Heron Caldas
Comments: 4 pages, 1 figure (eps), minor corrections in the text, conclusion
modified, typos corrected, references added
Subj-class: Superconductivity; Strongly Correlated Electrons
\\ ( http://arXiv.org/abs/cond-mat/0601148 ,  32kb)
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Paper: cond-mat/0603489
replaced with revised version Thu, 6 Apr 2006 22:21:12 GMT   (420kb)
Title: Comment on "Pairing and Phase Separation in a Polarized Fermi Gas" by G.
B. Partridge, W. Li, R. I. Kamar, Y. Liao, R. G. Hulet, Science 311, 503
(2006)
Authors: Martin W. Zwierlein and Wolfgang Ketterle
Comments: revised version with more thorough discussion on local density
approximation and phase separation
Subj-class: Superconductivity; Strongly Correlated Electrons
\\ ( http://arXiv.org/abs/cond-mat/0603489 ,  420kb)
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Paper: physics/0604061
Date: Fri, 7 Apr 2006 13:48:11 GMT   (751kb)
Title: 6-axis inertial sensor using cold-atom interferometry
Authors: B. Canuel, F. Leduc, D. Holleville, A. Gauguet, J. Fils, A. Virdis, A.
Clairon, N. Dimarcq, Ch. J. Borde, A. Landragin
Comments: 4 pages, 6 figures
Subj-class: Atomic Physics
\\
We have developed an atom interferometer providing a full inertial base. This
device uses two counter-propagating cold-atom clouds that are launched in
strongly curved parabolic trajectories. Three single Raman beam pairs, pulsed
in time, are successively applied in three orthogonal directions leading to the
measurement of the three axis of rotation and acceleration. In this purpose, we
introduce a new atom gyroscope using a butterfly geometry. We discuss the
present sensitivity and the possible improvements.
\\ ( http://arXiv.org/abs/physics/0604061 ,  751kb)
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Paper: cond-mat/0604216
Date: Fri, 7 Apr 2006 23:46:01 GMT   (67kb)
Title: Optimal conversion of Bose condensed atoms into molecules via a Feshbach
resonance
Authors: Jaeyoon Jeong, Chris P. Search, and Ivana Djuric
Subj-class: Other
\\
In many experiments involving conversion of quantum degenerate atomic gases
into molecular dimers via a Feshbach resonance, an external magnetic field is
linearly swept from above the resonance to below resonance. In the adiabatic
limit, the fraction of atoms converted into molecules is independent of the
functional form of the sweep and is predicted to be 100%. However, for
non-adiabatic sweeps through resonance, Landau-Zener theory predicts that a
linear sweep will result in a negligible production of molecules. Here we
employ a genetic algorithm to determine the functional time dependence of the
magnetic field that produces the maximum number of molecules for sweep times
that are comparable to the period of resonant atom-molecule oscillations,
$2\pi\Omega_{Rabi}^{-1}$. The optimal sweep through resonance indicates that
more than 95% of the atoms can be converted into molecules for sweep times as
short as $2\pi\Omega_{Rabi}^{-1}$ while the linear sweep results in a
conversion of only a few percent. We also find that the qualitative form of the
optimal sweep is independent of the strength of the two-body interactions
between atoms and molecules and the width of the resonance.
\\ ( http://arXiv.org/abs/cond-mat/0604216 ,  67kb)
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Paper: cond-mat/0604232
Date: Sun, 9 Apr 2006 09:43:22 GMT   (346kb)
Title: 3D strong localization of matter waves by scattering off atoms in a
lattice with a confinement-induced resonance
Authors: Pietro Massignan (LKB - Lhomond), Yvan Castin (LKB - Lhomond)
Comments: 20 pages; 14 figures
Proxy: ccsd ccsd-00022452
Subj-class: Disordered Systems and Neural Networks
\\
The possibility of using ultracold atoms to observe strong localization of
matter waves is now the subject of a great interest, as undesirable decoherence
and interactions can be made negligible in these systems. It was proposed that
a static disordered potential can be realized by trapping atoms of a given
species in randomly chosen sites of a deep 3D optical lattice with no multiple
occupation. We analyze in detail the prospects of this scheme for observing
localized states in 3D for a matter wave of a different atomic species that
interacts with the trapped particles and that is sufficiently far detuned from
the optical lattice to be insensitive to it. We demonstrate that at low energy
a large number of 3D strongly localized states can be produced for the matter
wave, if the effective scattering length describing the interaction of the
matter wave with a trapped atom is of the order of the mean distance between
the trapped particles. Such high values of the effective scattering length can
be obtained by using a Feshbach resonance to adjust the free space
inter-species scattering length and by taking advantage of confinement-induced
resonances induced by the trapping of the scatterers in the lattice.
\\ ( http://arXiv.org/abs/cond-mat/0604232 ,  347kb)
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Paper: cond-mat/0604236
Date: Sun, 9 Apr 2006 17:14:26 GMT   (174kb)
Title: What is a Cooper pair ?
Authors: G. Ortiz and J. Dukelsky
Comments: Proccedings of the International Workshop on Condensed Matter
Theories held in Japan (Sept. 2005)
Subj-class: Superconductivity
\\
Recently, the nature of Cooper pairs in the BCS-BEC crossover has regained
attention due to the observation of a large fraction of preformed fermion pairs
on the BCS side of the Feshbach resonance in ultracold atomic Fermi gases.
While several theoretical explanations were proposed, the interpretations are
still controversial. The root of the controversy is understanding what
represents a Cooper pair in a correlated Fermi system. This paper discusses
these issues at the most elementary level.
\\ ( http://arXiv.org/abs/cond-mat/0604236 ,  174kb)
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Paper: cond-mat/0604241
Date: Mon, 10 Apr 2006 05:53:00 GMT   (151kb)
Title: Conserving Gapless Mean-Field Theory for Weakly Interacting Bose Gases
Authors: Takafumi Kita
Comments: 19 pages, 8 figures
Subj-class: Statistical Mechanics
Journal-ref: J. Phys. Soc. Jpn. 75, 044603 (2006)
\\
This paper presents a conserving gapless mean-field theory for weakly
interacting Bose gases. We first construct a mean-field Luttinger-Ward
thermodynamic functional in terms of the condensate wave function $\Psi$ and
the Nambu Green's function $\hat{G}$ for the quasiparticle field. Imposing its
stationarity respect to $\Psi$ and $\hat{G}$ yields a set of equations to
determine the equilibrium for general non-uniform systems. They have a
plausible property of satisfying the Hugenholtz-Pines theorem to provide a
gapless excitation spectrum. Also, the corresponding dynamical equations of
motion obey various conservation laws. Thus, the present mean-field theory
shares two important properties with the exact theory: conserving'' and
gapless.'' The theory is then applied to a homogeneous weakly interacting
Bose gas with s-wave scattering length $a$ and particle mass $m$ to clarify its
basic thermodynamic properties under two complementary conditions of constant
density $n$ and constant pressure $p$. The superfluid transition is predicted
to be first-order because of the non-analytic nature of the order-parameter
expansion near $T_{c}$ inherent in Bose systems, i.e., the Landau-Ginzburg
expansion is not possible here. The transition temperature $T_{c}$ shows quite
a different interaction dependence between the $n$-fixed and $p$-fixed cases.
In the former case $T_{c}$ increases from the ideal gas value $T_{0}$ as
$T_{c}/T_{0}= 1+ 2.33 an^{1/3}$, whereas it decreases in the latter as
$T_{c}/T_{0}= 1- 3.84a(mp/2\pi\hbar^{2})^{1/5}$. Temperature dependences of
basic thermodynamic quantities are clarified explicitly.
\\ ( http://arXiv.org/abs/cond-mat/0604241 ,  151kb)
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Paper: cond-mat/0604255
Date: Mon, 10 Apr 2006 16:33:05 GMT   (33kb)
Title: The Three-Boson System at Next-To-Next-To-Leading Order
Authors: L. Platter, D. R. Phillips
Comments: 20 pages, 3 eps figures
Subj-class: Other
\\
We discuss effective field theory treatments of the problem of three
particles interacting via short-range forces (range R >> a_2, with a_2 the
two-body scattering length). We show that forming a once-subtracted scattering
equation yields a scattering amplitude whose low-momentum part is
renormalization-group invariant up to corrections of O(R^3/a_2^3). Since
corrections of O(R/a_2) and O(R^2/a_2^2) can be straightforwardly included in
the integral equation's kernel, a unique solution for 1+2 scattering phase
shifts and three-body bound-state energies can be obtained up to this accuracy.
We use our equation to calculate the correlation between the binding energies
of Helium-4 trimers and the atom-dimer scattering length. Our results are in
excellent agreement with the recent three-dimensional Faddeev calculations of
Roudnev and collaborators that used phenomenological inter-atomic potentials.
\\ ( http://arXiv.org/abs/cond-mat/0604255 ,  33kb)
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Paper: cond-mat/0503264
replaced with revised version Mon, 10 Apr 2006 09:03:36 GMT   (72kb)
Title: Finite Temperature Excitations of a trapped Bose gas by Feynman-Kac path
integral approach
Authors: S. Datta
Comments: 35pages,16figures
Subj-class: Other
\\ ( http://arXiv.org/abs/cond-mat/0503264 ,  72kb)
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Paper: cond-mat/0505374
replaced with revised version Sun, 9 Apr 2006 18:59:31 GMT   (15kb)
Title: Spin 1/2 Fermions in the Unitary Regime: A Superfluid of a New Type
Authors: Aurel Bulgac, Joaquin E. Drut and Piotr Magierski
Comments: 4 pages, 1 figure, published version
Subj-class: Statistical Mechanics
Journal-ref: Phys. Rev. Lett. 96, 090404 (2006)
DOI: 10.1103/PhysRevLett.96.090404
\\ ( http://arXiv.org/abs/cond-mat/0505374 ,  15kb)
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Paper: cond-mat/0507233
replaced with revised version Mon, 10 Apr 2006 15:38:36 GMT   (49kb)
Title: Density distributions for trapped one-dimensional spinor gases
Authors: Yajiang Hao, Yunbo Zhang, J. Q. Liang, and Shu Chen
Comments: 6 pages, 3 figures, version to be published in Phys. Rev. A
Subj-class: Strongly Correlated Electrons
\\ ( http://arXiv.org/abs/cond-mat/0507233 ,  49kb)
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Paper: cond-mat/0509380
replaced with revised version Mon, 10 Apr 2006 19:58:31 GMT   (27kb)
Title: Vortex description of the fractionalized phase in exciton bose
condensate
Authors: Sung-Sik Lee, T. Senthil and Patrick A. Lee
Comments: 8 pages, 6 figures; clarification made in introduction
Subj-class: Strongly Correlated Electrons
\\ ( http://arXiv.org/abs/cond-mat/0509380 ,  27kb)
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Paper: cond-mat/0511675
replaced with revised version Sat, 8 Apr 2006 11:07:53 GMT   (187kb)
Title: Interference between independent fluctuating condensates
Authors: Anatoli Polkovnikov, Ehud Altman, Eugene Demler
Comments: 7 pages, 3 figures, published version
Subj-class: Statistical Mechanics
Journal-ref: PNAS 103, 6125 (2006)
DOI: 10.1073/pnas.0510276103
\\ ( http://arXiv.org/abs/cond-mat/0511675 ,  187kb)
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Paper: quant-ph/0604054
Date: Sun, 9 Apr 2006 05:30:09 GMT   (9kb)
Title: On the quantum master equation for fermions
Authors: C. F. Huang and K.-N. Huang
Comments: 15 pages
\\
A quantum master equation is obtained for identical fermions by including a
relaxation term in addition to the mean-field Hamiltonian. [C. F. Huang and
K.-N. Huang, Chinese J. Phys. ${\bf 42}$, 221 (2004); Ralph Gebauer and Roberto
Car, Phys. Rev. B ${\bf 70}$, 125324 (2004).] It is shown in this paper that
both the positivity and Pauli exclusion principle are preserved under this
quantum master equation when there exists an upper bound for the transition
rate. Such an equation can be reduced to a Markoff master equation of Lindblad
form in the low-density limit with respect to particles or holes.
\\ ( http://arXiv.org/abs/quant-ph/0604054 ,  9kb)
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Paper: quant-ph/0604055
Date: Sat, 8 Apr 2006 16:01:43 GMT   (28kb)
Title: About mathematical apparatus of many body quantum dynamics
Authors: Y.I.Ozhigov
Comments: 29 ges, Latex
\\
We discuss the possibility to modify many-body Hilbert quantum formalism that
is necessary for the representation of quantum systems dynamics. The notion of
effective classical algorithm and visualization of quantum dynamics play the
key role.
\\ ( http://arXiv.org/abs/quant-ph/0604055 ,  28kb)
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Paper: quant-ph/0604066
Date: Mon, 10 Apr 2006 12:06:54 GMT   (1599kb)
Title: Classical and Quantum Chaos in Atom Optics
Authors: Farhan Saif
Comments: 105 pages, 14 figures
Journal-ref: Physics Reports 419, 207 (2005); Physics Reports 425, 369 (2006)
\\
The interaction of an atom with an electromagnetic field is discussed in the
presence of a time periodic external modulating force. It is explained that a
control on atom by electromagnetic fields helps to design the quantum analog of
classical optical systems. In these atom optical systems chaos may appear at
the onset of external fields. The classical and quantum chaotic dynamics is
discussed, in particular in an atom optics Fermi accelerator. It is found that
the quantum dynamics exhibits dynamical localization and quantum recurrences.
\\ ( http://arXiv.org/abs/quant-ph/0604066 ,  1599kb)
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Paper: physics/0604079
Date: Mon, 10 Apr 2006 19:53:25 GMT   (539kb)
Title: Magnetic trapping of buffer-gas cooled chromium atoms and prospects for
the extension to paramagnetic molecules
Authors: Joost M. Bakker, Michael Stoll, Dennis R. Weise, Oliver Vogelsang,
Gerard Meijer, and Achim Peters
Comments: 8 pages, 4 Figures. Submitted to J.Phys. B, special issue on cold
molecules/
Subj-class: Atomic Physics
\\
We report the successful buffer-gas cooling and magnetic trapping of chromium
atoms with densities exceeding 10^12 atoms per cm^3 at a temperature of 350 mK
for the trapped sample. The possibilities to extend the method to buffer gas
cool and magnetically trap molecules are discussed. To minimize the most
important loss mechanism in magnetic trapping, molecules with a small spin-spin
interaction and a large rotational constant are preferred. Both the CrH
(6Sigma+ ground state) and MnH (7Sigma+) radicals appear to be suitable systems
for future experiments.
\\ ( http://arXiv.org/abs/physics/0604079 ,  539kb)
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Paper: physics/0604077
Date: Mon, 10 Apr 2006 10:38:38 GMT   (100kb)
Title: Do we have enough air?
Authors: V.Dorobantu
Comments: 3 pages
Subj-class: Physics Education
\\
If only human beings would breathe the entire quantity of terrestrial air,
then, at the present-day population on the Earth, one million years would
exhaust that air. It seems we have enough air. Is it so?
\\ ( http://arXiv.org/abs/physics/0604077 ,  100kb)
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Paper: cond-mat/0604273
Date: Tue, 11 Apr 2006 12:24:20 GMT   (267kb)
Title: Topological constraints on magnetostatic traps
Authors: R. Gerritsma and R. J. C. Spreeuw
Comments: 7 pages, 5 figures
Subj-class: Other
\\
We theoretically investigate properties of magnetostatic traps for cold atoms
that are subject to externally applied uniform fields. We show that Ioffe
Pritchard traps and other stationary points of $B$ are confined to a
two-dimensional curved manifold defined by $\det(\partial B_i/\partial x_j)=0$.
We describe how stationary points can be moved over the manifold by applying
external uniform fields. The manifold also plays an important role in the
behavior of points of zero field. Field zeroes occur in two distinct types, in
separate regions of space divided by the manifold. Pairs of zeroes of opposite
type can be created or annihilated on the manifold. Finally, we give examples
of the manifold for cases of practical interest.
\\ ( http://arXiv.org/abs/cond-mat/0604273 ,  267kb)
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Paper: cond-mat/0604282
Date: Tue, 11 Apr 2006 16:28:35 GMT   (22kb)
Title: Pair correlations of an expanding superfluid Fermi gas
Authors: C. Lobo, I. Carusotto, S. Giorgini, A. Recati, S. Stringari
Comments: 4 pages, 1 figure
Subj-class: Soft Condensed Matter
\\
The pair correlation function of an expanding gas is investigated with an
emphasis on the BEC-BCS crossover of a superfluid Fermi gas at zero
temperature. At unitarity quantum Monte Carlo simulations reveal the occurrence
of a sizable bunching effect due to interactions in the spin up-down channel
which, at short distances, is larger than that exhibited by thermal bosons in
the Hanbury-Brown and Twiss effect. We propose a local equilibrium ansatz for
the pair correlation function which we predict will remain isotropic during the
expansion even if the trapping potential is anisotropic, contrary to what
happens for non-interacting gases. This behavior is understood to be a
consequence of the violation of scaling of the pair correlation function due to
interactions.
\\ ( http://arXiv.org/abs/cond-mat/0604282 ,  22kb)
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Paper: cond-mat/0511709
replaced with revised version Tue, 11 Apr 2006 15:41:43 GMT   (76kb)
Title: Adiabatic-Impulse approximation for avoided level crossings: from phase
transition dynamics to Landau-Zener evolutions and back again
Authors: Bogdan Damski and Wojciech H. Zurek
Comments: 12 pages & 6 figures, minor corrections, version accepted in Phys.
Rev. A
Report-no: LAUR# 05-8597
Subj-class: Other
\\ ( http://arXiv.org/abs/cond-mat/0511709 ,  76kb)
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Paper: cond-mat/0602240
replaced with revised version Tue, 11 Apr 2006 08:53:21 GMT   (155kb)
Title: Bragg spectroscopy of trapped one dimensional strongly interacting
bosons in optical lattices: Probing the cake-structure
Authors: Guido Pupillo, Ana Maria Rey and G. George Batrouni
Comments: 7 pages, 4 figures
Subj-class: Other
\\ ( http://arXiv.org/abs/cond-mat/0602240 ,  155kb)
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Paper: quant-ph/0604074
Date: Tue, 11 Apr 2006 09:17:16 GMT   (20kb)
Title: Thermal limitation of far-field matter-wave interference
Authors: Klaus Hornberger
Comments: 8 pages, 2 figures; to appear in Phys Rev A
\\
We asses the effect of the heat radiation emitted by mesoscopic particles on
their ability to show interference in a double slit arrangement. The analysis
is based on a stationary, phase-space based description of matter wave
interference in the presence of momentum-exchange mediated decoherence.
\\ ( http://arXiv.org/abs/quant-ph/0604074 ,  20kb)
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Paper: quant-ph/0604080
Date: Tue, 11 Apr 2006 16:57:17 GMT   (269kb)
Title: Hawking radiation effect on fermions and information loss in black holes
Authors: Doyeol Ahn
Comments: Submittted to Nature on March 28, 2006
\\
Hawking radiation1-4 (quantum thermal radiation from the black hole) and its
effect on information loss in black holes5-10 have been a serious challenge to
modern physics because they require a clear understanding of phenomena ranging
from gravity to quantum mechanics and particle physics to information theory.
The essence of Hawking radiation on the scalar particles is that an observer at
rest outside a black hole or a uniformly accelerated observer (Rindler
spacetime) in the flat spacetime sees a thermal bath of particles11-13. On the
other hand, Hawking radiation effect on fermions (particles with half-integer
spin) and information loss is not so well understood. Here we report that the
Hawking radiation effect on fermions is fundamentally different from the case
of scalar particles. Our study shows that the intrinsic properties of fermions
(exclusion principle and spin) affect strongly the interaction of fermions with
both Hawking radiation and metric of the spacetime. In particular we have found
the following: first, while the fermion vacuum state seen by the Rindler
observer is an entangled state in which the right and left Rindler wedge states
appear in correlated pairs as in the case of the scalar particles, the
entanglement disappears in the excited state due to the exclusion principle;
second, the spin of the fermion experiences a non-unitary Winger rotation14,15
under a uniform acceleration; and third, the quantum information of fermions is
dissipated not by the Hawking radiation but by the Wigner rotation. As a
result, information loss in a black hole is quite different for scalar
particles and fermions. Part of the information survives for scalar
particles16. For fermions, it is dissipated irreversibly into the curvature of
the spacetime.
\\ ( http://arXiv.org/abs/quant-ph/0604080 ,  269kb)
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Paper (*cross-listing*): nucl-th/0601077
Date: Wed, 25 Jan 2006 09:04:35 GMT   (88kb)
Date (revised v2): Tue, 11 Apr 2006 15:18:13 GMT   (90kb)
Title: Nuclear quantum optics with x-ray laser pulses
Authors: Thomas J. Buervenich, Joerg Evers, Christoph H. Keitel
Comments: 5 pages, 3 eps figures, revised version
Journal-ref: Phys. Rev. Lett. 96, 142501 (2006)
\\
The direct interaction of nuclei with super-intense laser fields is studied.
We show that present and upcoming high-frequency laser facilities, especially
together with a moderate acceleration of the target nuclei, do allow for
resonant laser-nucleus interaction. These direct interactions may be utilized
for the optical measurement of nuclear properties such as the transition
frequency and the dipole moment, thus opening the field of nuclear quantum
optics. As ultimate goal, one may hope that direct laser-nucleus interactions
could become a versatile tool to enhance preparation, control and detection in
nuclear physics.
\\ ( http://arXiv.org/abs/nucl-th/0601077 ,  90kb)
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Paper: physics/0604082
Date: Tue, 11 Apr 2006 04:11:06 GMT   (230kb)
Title: Atom interferometer as a selective sensor of rotation or gravity
Authors: B. Dubetsky and M. A. Kasevich
Comments: 21 pages, 4 figures
Subj-class: Atomic Physics
\\
In the presence of Earth gravity and gravity-gradient forces, centrifugal and
Coriolis forces caused by the Earth rotation, the phase of the time-domain atom
interferometers is calculated with accuracy up to the terms proportional to the
fourth degree of the time separation between pulses. We considered double-loop
atom interferometers and found appropriate condition to eliminate their
sensitivity to acceleration to get atomic gyroscope, or to eliminate the
sensitivity to rotation to increase accuracy of the atomic gravimeter.
Consequent use of these interferometers allows one to measure all components of
the acceleration and rotation frequency projection on the plane perpendicular
to gravity acceleration. Atom interference on the Raman transition driving by
non-counterpropagating optical fields is proposed to exclude stimulated echo
processes which can affect the accuracy of the atomic gyroscopes. Using
non-counterpropagating optical fields allows one to get new type of the Ramsey
fringes arising in the unidirectional Raman pulses and therefore centered at
the two-quantum line center. Density matrix in the Wigner representation is
used to perform calculations. It is shown that in the time between pulses, in
the non-inertial frame, for atoms with fully quantized spatial degrees of
freedom, this density matrix obeys classical Liouville equations.
\\ ( http://arXiv.org/abs/physics/0604082 ,  230kb)
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Paper: physics/0604087
Date: Tue, 11 Apr 2006 08:03:39 GMT   (428kb)
Title: A definitive number of atoms on demand: controlling the number of atoms
in a-few-atom magneto-optical trap
Authors: Seokchan Yoon, Youngwoon Choi, Sangbum Park, Jaisoon Kim, Jai-Hyung
Lee, and Kyungwon An
Comments: 3 pages, 4 figures
Subj-class: Atomic Physics
\\
A few 85Rb atoms were trapped in a micron-size magneto-optical trap with a
high quadrupole magnetic-field gradient and the number of atoms was precisely
controlled by suppressing stochastic loading and loss events via real-time
feedback on the magnetic field gradient. The measured occupation probability of
single atom was as high as 99%. Atoms up to five were also trapped with high
occupation probabilities. The present technique could be used to make a
deterministic atom source.
\\ ( http://arXiv.org/abs/physics/0604087 ,  428kb)
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Paper: physics/0604088
Date: Tue, 11 Apr 2006 10:12:43 GMT   (711kb)
Title: Dependence of fluorescence-level statistics on bin time size in a
few-atom magneto-optical trap
Authors: Sungsam Kang, Seokchan Yoon, Youngwoon Choi, Jai-Hyung Lee, and
Kyungwon An
Comments: 9 pages, 9 figures
Subj-class: Atomic Physics
\\
We have analyzed the statistical distribution of the fluorescence signal
levels in a magneto-optical trap containing a few atoms and observed that it
strongly depends on the relative size of the bin time with respect to the trap
decay time. We derived analytic expressions for the signal distributions in two
limiting cases, long and short bin time limits, and found good agreement with
numerical simulations performed regardless of the size of the bin time. We
found an optimal size of the bin time for minimizing the probability of
indeterminate atom numbers while providing accurate information on the
instantaneous number of atoms in the trap. These theoretical results are
compared with actual experimental data. We observed super-Poisson counting
statistics for the fluorescence from trapped atoms, which might be attributed
to uncorrelated motion of trapped atoms in the inhomogeneous magnetic field in
the trap.
\\ ( http://arXiv.org/abs/physics/0604088 ,  711kb)
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Paper: physics/0408088
replaced with revised version Tue, 11 Apr 2006 15:34:52 GMT   (426kb)
Title: Classical diffusion in double-delta-kicked particles
Authors: M.M.A. Stocklin and T.S. Monteiro
Comments: 14 pages, 10 figures
Subj-class: Atomic Physics
\\ ( http://arXiv.org/abs/physics/0408088 ,  426kb)
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Paper: cond-mat/0604311
Date: Wed, 12 Apr 2006 12:58:18 GMT   (27kb)
Title: The exciton many-body theory extended to arbitrary composite bosons
Authors: M. Combescot, O.Betbeder-Matibet, F. Dubin
Subj-class: Mesoscopic Systems and Quantum Hall Effect
\\
We have recently constructed a many-body theory for composite excitons, in
which the possible carrier exchanges between $N$ excitons can be treated
exactly through a set of dimensionless Pauli scatterings'' between two
excitons. Many-body effects with excitons turn out to be rather simple because
excitons are the exact one-electron-hole-pair eigenstates of the semiconductor
Hamiltonian, thus forming a complete orthogonal set for one-pair states. It can
however be of interest to extend this new many-body theory to more complicated
composite bosons, \emph{i. e.}, cobosons'', which are not necessarily the
one-pair eigenstates of the system Hamiltonian, nor even orthogonal. The
purpose of this paper is to derive the Pauli scatterings'' and the
interaction scatterings'' of these cobosons formally, \emph{i. e.}, just in
terms of their wave functions and the interaction potentials which exist
between the fermions from which they are constructed. We also explain how to
derive many-body effects in this very general system of composite bosons.
\\ ( http://arXiv.org/abs/cond-mat/0604311 ,  27kb)
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Paper: cond-mat/0604312
Date: Wed, 12 Apr 2006 13:22:15 GMT   (191kb)
Title: Analysis of light-induced frequency shifts in the photoassociation of
ultracold metastable helium atoms
Authors: Maximilien Portier (LKB - Lhomond), Steven Moal (LKB - Lhomond),
Jaewan Kim (LKB - Lhomond), Mich\{e}le Leduc (LKB - Lhomond), Claude
Cohen-Tannoudji (LKB - Lhomond), Olivier Dulieu (LAC)
Comments: 28 pages, 7 figures, submitted to the special issue on Cold Molecules
of J. Phys. B
Proxy: ccsd ccsd-00022678
Subj-class: Other
\\
We present an exhaustive analysis of the light-induced frequency shifts of
the photoassociation lines of ultracold metastable 4He* atoms in a magnetic
trap. The measurements of the shifts of several vibrational levels bound in the
purely long-range J=1,0u+ potential linked to the 23S1-23P0 asymptote were
reported in a previous paper and are analyzed here. The simplicity of this
system makes it very appropriate for a detailed study. Indeed, the purely
long-range character of the excited potential allows one to calculate exact
excited molecular wavefunctions and to use asymptotic expansions at large
internuclear distances of the ground state wavefunctions appearing in
Franck-Condon type integrals. Moreover, the number of collisional channels to
be considered is strongly reduced by the absence of hyperfine structure for
4He* and the use of polarized ultracold atoms and polarized light. This allows
us to derive semi-analytical expressions for the shifts showing explicitly
their linear dependences on the s-wave scattering length a of spin polarized
metastable 4He* atoms. This explains how it is possible to derive the
measurement of a from these shifts.
\\ ( http://arXiv.org/abs/cond-mat/0604312 ,  191kb)
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Paper: quant-ph/0604082
Date: Wed, 12 Apr 2006 08:08:21 GMT   (112kb)
Title: Aspects of quantum coherence in the optical Bloch equations
Authors: A. S. Sanz, H. Han, and P. Brumer
Comments: 18 pages, 6 figures; to appear in J Chem Phys
\\
Aspects of coherence and decoherence are analyzed within the optical Bloch
equations. By rewriting the analytic solution in an alternate form, we are able
to emphasize a number of unusual features: (a) despite the Markovian nature of
the bath, coherence at long times can be retained; (b) the long-time asymptotic
degree of coherence in the system is intertwined with the asymptotic difference
in level populations; (c) the traditional population-relaxation and decoherence
times, $T_1$ and $T_2$, lose their meaning when the system is in the presence
of an external field, and are replaced by more general overall timescales; (d)
increasing the field strength, quantified by the Rabi frequency, $\Omega$,
increases the rate of decoherence rather than reducing it, as one might expect;
and (e) maximum asymptotic coherence is reached when the system parameters
satisfy $\Omega^2 = 1/(T_1 T_2)$.
\\ ( http://arXiv.org/abs/quant-ph/0604082 ,  112kb)
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Paper: cond-mat/0604330
Date: Thu, 13 Apr 2006 01:52:19 GMT   (150kb)
Title: Bragg scattering of Cooper pairs in an ultra-cold Fermi gas
Authors: K. J. Challis, R. J. Ballagh, and C. W. Gardiner
Subj-class: Other
\\
We present a theoretical treatment of Bragg scattering of a degenerate Fermi
gas, based on the time-dependent Bogoliubov de Gennes equations. Numerical
solutions show that, in addition to the expected single-particle Bragg
scattering, correlated scattering of atom pairs occurs via a grating formed in
the pair potential. The correlated-pair Bragg scattering has a sharp frequency
threshold, beyond which the scattered pairs form a spherical shell in momentum
space that is centered at half the usual Bragg momentum transfer. We develop an
analytic model that explains key features of correlated-pair Bragg scattering.
\\ ( http://arXiv.org/abs/cond-mat/0604330 ,  150kb)
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Paper: cond-mat/0604339
Date: Thu, 13 Apr 2006 13:05:11 GMT   (586kb)
Title: Generic Phase Diagram of Fermion Superfluids with Population Imbalance
Authors: K. Machida, T. Mizushima, M. Ichioka
Comments: 5 pages, 5 figuess
Subj-class: Superconductivity
\\
It is shown by microscopic calculations for trapped imbalanced Fermi
superfluids that the gap function has always sign changes, or is
Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state like, up to a critical imbalance
$P_c$ at temperature T=0. A phase diagram is constructed in $T$ vs $P$, where
the BCS state without sign change is stable only at $T \neq 0$. We reproduce
the observed bimodality in the density profile to identify its origin and
evaluate $P_c$ as functions of $T$ and the coupling strength. These
dependencies match with the recent experiments.
\\ ( http://arXiv.org/abs/cond-mat/0604339 ,  586kb)
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Paper: cond-mat/0604348
Date: Thu, 13 Apr 2006 15:55:58 GMT   (252kb)
Title: Realization of a single Josephson junction for Bose-Einstein condensates
Authors: Rudolf Gati, Micheal Albiez, Jonas Foelling, Boerge Hemmerling, Markus
K. Oberthaler
Subj-class: Other
Journal-ref: Appl. Phys. B 82, 207 (2006)
DOI: 10.1007/s00340-005-2059-z
\\
We report on the realization of a double-well potential for Rubidium-87
Bose-Einstein condensates. The experimental setup allows the investigation of
two different dynamical phenomena known for this system - Josephson
oscillations and self-trapping. We give a detailed discussion of the
experimental setup and the methods used for calibrating the relevant
parameters. We compare our experimental findings with the predictions of an
extended two-mode model and find quantitative agreement.
\\ ( http://arXiv.org/abs/cond-mat/0604348 ,  252kb)
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Paper: cond-mat/0604357
Date: Thu, 13 Apr 2006 18:19:25 GMT   (10kb)
Title: Anyon-fermion mapping and applications to ultracold gases in tight
waveguides
Authors: M. D. Girardeau
Comments: 4 pages, revtex4, submitted to Phys. Rev. Lett
Subj-class: Soft Condensed Matter
\\
The Fermi-Bose mapping method for one-dimensional (1D) Bose and Fermi gases
with zero-range interactions is generalized to an anyon-fermion mapping and
applied to exact solution of several models of ultracold gases with anyonic
exchange symmetry in tight waveguides: anyonic Calogero-Sutherland model,
anyons with point hard core interaction ("anyonic TG gas"), and spin-aligned
anyon gas with infinite zero-range odd-wave attractions ("anyonic FTG gas"). It
is proved that for even $N\ge 4$ there are states of the anyonic FTG gas on a
ring, with anyonic phase slips which are odd integral multiples of $\pi/(N-1)$,
of energy lower than that of the corresponding fermionic ground state. A
generalization to a spinor Fermi gas state with anyonic symmetry under purely
spatial exchange enables energy lowering by the same mechanism.
\\ ( http://arXiv.org/abs/cond-mat/0604357 ,  10kb)
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Paper: cond-mat/0511647
replaced with revised version Thu, 13 Apr 2006 08:44:03 GMT   (21kb)
Title: Thermodynamic properties of a trapped Bose gas : A diffusion Monte Carlo
study
Authors: S Datta
Comments: 9 pages, 12 figures
Subj-class: Statistical Mechanics
\\ ( http://arXiv.org/abs/cond-mat/0511647 ,  21kb)
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Paper: cond-mat/0601147
replaced with revised version Thu, 13 Apr 2006 12:23:49 GMT   (888kb)
Title: LOFF Pairing vs. Breached Pairing in Asymmetric Fermion Superfluids
Authors: Lianyi He, Meng Jin and Pengfei Zhuang
Comments: 11 pages, 13 figures, error corrected, numerical results for
different regularization shemes checked. Submitted for publication
Subj-class: Superconductivity
\\ ( http://arXiv.org/abs/cond-mat/0601147 ,  888kb)
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Paper: cond-mat/0602483
replaced with revised version Thu, 13 Apr 2006 02:42:23 GMT   (83kb)
Title: Ground state properties of finite ultracold Bose gases in a hard-wall
trap
Authors: Yajiang Hao, Yunbo Zhang, J.-Q. Liang and Shu Chen
Comments: 7 pages, 6 figures, significant extensions made and a new figure
added
Subj-class: Strongly Correlated Electrons
\\ ( http://arXiv.org/abs/cond-mat/0602483 ,  83kb)
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Paper: cond-mat/0603754
replaced with revised version Thu, 13 Apr 2006 04:46:53 GMT   (17kb)
Title: Bose-Einstein Condensation with Entangled Order Parameter
Authors: Yu Shi, Qian Niu
Comments: V1: 5 pages, 4 figures. Accepted by Phys. Rev. Lett.; V2: A couple of
very minor typos corrected, published
Subj-class: Other
Journal-ref: Phys. Rev. Lett. 96, 140401 (2006)
DOI: 10.1103/PhysRevLett.96.140401
\\ ( http://arXiv.org/abs/cond-mat/0603754 ,  17kb)
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Paper: quant-ph/0604097
Date: Thu, 13 Apr 2006 12:47:03 GMT   (117kb)
Title: Quantum criticality in a generalized Dicke model
Authors: Y. Li, Z. D. Wang, and C. P. Sun
Comments: 4 pages, 3 figures
\\
We employ a generalized Dicke model to study theoretically the quantum
criticality of an extended two-level atomic ensemble interacting with a
single-mode quantized light field. Effective Hamiltonians are derived and
digonalized to investigate numerically their eigenfrequencies for different
quantum phases in the system. Based on the analysis of the eigenfrequencies, an
intriguing quantum phase transition from a normal phase to a super-radiant
phase is revealed clearly, which is quite different from that observed with a
standard Dicke model.
\\ ( http://arXiv.org/abs/quant-ph/0604097 ,  117kb)
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Paper (*cross-listing*): cond-mat/0603754
Date: Tue, 28 Mar 2006 12:43:54 GMT   (17kb)
Date (revised v2): Thu, 13 Apr 2006 04:46:53 GMT   (17kb)
Title: Bose-Einstein Condensation with Entangled Order Parameter
Authors: Yu Shi, Qian Niu
Comments: V1: 5 pages, 4 figures. Accepted by Phys. Rev. Lett.; V2: A couple of
very minor typos corrected, published
Subj-class: Other
Journal-ref: Phys. Rev. Lett. 96, 140401 (2006)
DOI: 10.1103/PhysRevLett.96.140401
\\
We propose a practically accessible non-mean-field ground state of
Bose-Einstein condensation (BEC), which occurs in an interspecies two-particle
entangled state, and is thus described by an entangled order parameter. A
suitably defined entanglement entropy is used as the characterization of the
non-mean-field nature, and is found to persist in a wide parameter regime. The
interspecies entanglement leads to novel interference terms in the dynamical
equations governing the single particle orbital wavefunctions. Experimental
feasibility and several methods of probe are discussed. We urge the study of
multi-channel scattering between different species of atoms.
\\ ( http://arXiv.org/abs/cond-mat/0603754 ,  17kb)
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Paper: cond-mat/0604371
Date: Fri, 14 Apr 2006 13:03:58 GMT   (32kb)
Title: The origin of phase in the interference of Bose-Einstein condensates
Authors: W. J. Mullin, R. Krotkov, and F. Lalo\"{e}
Comments: 22 pages 4 figures
Subj-class: Other; Statistical Mechanics
\\
We consider the interference of two overlapping ideal Bose-Einstein
condensates. The usual description of this phenomenon involves the introduction
of a so-called condensate wave functions having a definite phase. We
investigate the origin of this phase and the theoretical basis of treating
interference. It is possible to construct a phase state, for which the particle
number is uncertain, but phase is known. However, how one would prepare such a
state before an experiment is not obvious. We show that a phase can also arise
from experiments using condensates in Fock states, that is, having known
particle numbers. Analysis of measurements in such states also gives us a
prescription for preparing phase states. The connection of this procedure to
questions of spontaneously broken gauge symmetry'' and to hidden
variables'' is mentioned.
\\ ( http://arXiv.org/abs/cond-mat/0604371 ,  32kb)
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Paper: cond-mat/0601604
replaced with revised version Fri, 14 Apr 2006 09:34:11 GMT   (187kb)
Title: Thermal fluctuations of vortex clusters in quasi two-dimensional
Bose-Einstein condensate
Authors: W. V. Pogosov and K. Machida
Comments: 8 pages, 4 figures
Subj-class: Statistical Mechanics; Other
\\ ( http://arXiv.org/abs/cond-mat/0601604 ,  187kb)
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Paper: quant-ph/0604103
Date: Fri, 14 Apr 2006 05:50:18 GMT   (130kb)
Title: A novel interferometer to beat the standard quantum limit using optical
transverse modes in multimode waveguide
Authors: Jian Fu
Comments: 9 pages, 5 figures
\\
We propose a novel interferometer by using optical transverse modes in
multimode waveguide that can beat the standard quantum limit. In the scheme,
the classical simulation of $N$-partical quantum entangled states is generated
by using $N$ independent classical fields and linear optical elements. Similar
to the quantum-enhanced measurements, the classical simulation can also achieve
$\sqrt{N}$ enhancement over the precision of the measurement $N$ times for
independent fields. Due to only using classical fields and linear optical
elements, the scheme can be realized much more easily.
\\ ( http://arXiv.org/abs/quant-ph/0604103 ,  130kb)
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Paper (*cross-listing*): nlin.PS/0504061
Date: Fri, 29 Apr 2005 11:06:48 GMT   (39kb)
Date (revised v2): Wed, 25 Jan 2006 13:22:53 GMT   (69kb)
Title: Spatial dispersive shock waves generated in supersonic flow of
Bose-Einstein condensate past slender body
Authors: G.A. El and A.M. Kamchatnov
Comments: 10 pages, revised version with additions and corrections
Subj-class: Pattern Formation and Solitons; Soft Condensed Matter
Journal-ref: Phys. Lett. A 350, 192-196 (2006)
\\
Supersonic flow of Bose-Einstein condensate past macroscopic obstacles is
studied theoretically. It is shown that in the case of large obstacles the
Cherenkov cone transforms into a stationary spatial shock wave which consists
of a number of spatial dark solitons. Analytical theory is developed for the
case of obstacles having a form of a slender body. This theory explains
qualitatively the properties of such shocks observed in recent experiments on
nonlinear dynamics of condensates of dilute alkali gases.
\\ ( http://arXiv.org/abs/nlin/0504061 ,  69kb)
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Paper (*cross-listing*): nucl-th/0604028
Date: Wed, 12 Apr 2006 12:47:16 GMT   (108kb)
Title: Two-body correlation functions in nuclear matter with $np$ condensate
Authors: A.A. Isayev
Comments: Prepared with RevTeX4, 5p., 4 figures
Subj-class: Nuclear Theory; Other
\\
The density, spin and isospin correlation functions in nuclear matter with a
neutron-proton ($np$) condensate are calculated to study the possible
signatures of the BEC-BCS crossover in the low-density region. It is shown that
the criterion of the crossover (Phys. Rev. Lett. {\bf 95}, 090402 (2005)),
consisting in the change of the sign of the density correlation function at low
momentum transfer, fails to describe correctly the density-driven BEC-BCS
transition at finite isospin asymmetry or finite temperature. As an unambiguous
signature of the BEC-BCS transition, there can be used the presence (BCS
regime) or absence (BEC regime) of the singularity in the momentum distribution
of the quasiparticle density of states.
\\ ( http://arXiv.org/abs/nucl-th/0604028 ,  108kb)
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Paper: cond-mat/0511514
replaced with revised version Mon, 17 Apr 2006 13:22:45 GMT   (30kb)
Title: Effect of the Zero-Mode on the Response of a Trapped Bose-Condensed Gas
Authors: Makoto Mine, Tomoi Koide, Masahiko Okumura, Yoshiya Yamanaka
Comments: 18 pages, 3 figures
Subj-class: Other
\\ ( http://arXiv.org/abs/cond-mat/0511514 ,  30kb)
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Paper (*cross-listing*): nlin.PS/0507025
replaced with revised version Sun, 16 Apr 2006 23:52:53 GMT   (906kb)
Title: Feshbach Resonance Management of Bose-Einstein Condensates in Optical
Lattices
Authors: Mason A. Porter, Marina Chugunova, and Dmitry E. Pelinovsky
Comments: 8 pages, 5 figures (1 with six parts, 4 with two parts), submitted to
Physical Review E
Subj-class: Pattern Formation and Solitons; Other; Atomic Physics; Dynamical
Systems
\\ ( http://arXiv.org/abs/nlin/0507025 ,  906kb)
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Paper: quant-ph/0604110
Date: Sat, 15 Apr 2006 23:12:16 GMT   (174kb)
Title: Observation of high-order quantum resonances in the kicked rotor
Authors: J.F. Kanem, S. Maneshi, M. Partlow, M. Spanner and A.M. Steinberg
\\
Quantum resonances in the kicked rotor are characterized by a dramatically
increased energy absorption rate, in stark contrast to the momentum
localization generally observed. These resonances occur when the scaled
Planck's constant hbar=(r/s)*4pi, for any integers r and s. However only the
hbar=r*2pi resonances are easily observable. We have observed high-order
quantum resonances (s>2) utilizing a sample of low temperature, non-condensed
atoms and a pulsed optical standing wave. Resonances are observed for
hbar=(r/16)*4pi r=2-6. Quantum numerical simulations suggest that our
observation of high-order resonances indicates a larger coherence length than
expected from an initially thermal atomic sample.
\\ ( http://arXiv.org/abs/quant-ph/0604110 ,  174kb)
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Received on Tue Apr 18 2006 - 15:12:42 EST

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