Dear subscribers,
Andy Ferris has compiled this week's mailing. It has 30 new preprints and 11
replacements:
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arXiv:0905.0052
Date: Fri, 1 May 2009 06:10:07 GMT (359kb)
Title: Optimised control of Stark-shift-chirped rapid-adiabatic-passage in a
lambda-type three-level system
Authors: Johann-Heinrich Sch\"onfeldt, Jason Twamley, Stojan Rebi\'c
Categories: quant-ph
Comments: 6 pages, 6 figures, 1 table
\\
Inhomogeneous broadening of energy levels is one of the principal limiting
factors for achieving "slow" or "stationary" light in solid state media by
means of electromagnetically induced transparency (EIT), a quantum version of
stimulated Raman adiabatic passage (STIRAP). Stark-shift-chirped
rapid-adiabatic-passage (SCRAP) has been shown to be far less sensitive to
inhomogeneous broadening than STIRAP, a population transfer technique to which
it is closely related. We further optimise the pulses used in SCRAP to be even
less sensitive to inhomogeneous broadening in a lambda-type three-level system.
The optimised pulses perform at a higher fidelity than the standard gaussian
pulses for a wide range of detunings (i.e. large inhomogeneous broadening).
\\ ( http://arxiv.org/abs/0905.0052 , 359kb)
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arXiv:0905.0093
Date: Fri, 1 May 2009 14:03:14 GMT (117kb)
Title: Extended solutions via the trial-orbit method for two-field models
Authors: A. R. Gomes, D. Bazeia
Categories: physics.optics
Comments: 14 pages, 4 figures
Journal-ref: Phys. Scr. 79 (2009) 055005
DOI: 10.1088/0031-8949/79/05/055005
\\
In this work we investigate the presence of defect structures in models
described by two real scalar fields. The coupling between the two fields is
inspired on the equations for a multimode laser, and the minimum energy trivial
configurations are shown to be structurely dependent on the parameters of the
models. The trial orbit method is then used and several non-trivial analytical
solutions corresponding to topological solitons are obtained.
\\ ( http://arxiv.org/abs/0905.0093 , 117kb)
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arXiv:0905.0111
Date: Fri, 1 May 2009 16:13:21 GMT (227kb)
Title: On the Burgers vector of a wave dislocation
Authors: Mark R. Dennis
Categories: physics.optics
Comments: 15 pages, 4 figures, IoP style
\\
Following Nye and Berry's analogy with crystal dislocations, an approach to
the Burgers vector of a wave dislocation (phase singularity, optical vortex) is
proposed. It is defined to be a regularized phase gradient evaluated at the
phase singularity, and is computed explicitly. The screw component of this
vector is naturally related to the helicoidal twisting of wavefronts along a
vortex line, and is related to the helicity of the phase gradient. The edge
component is related to the nearby current flow (defined by the phase gradient)
perpendicular to the vortex, and the distribution of this component is found
numerically for random two-dimensional monochromatic waves.
\\ ( http://arxiv.org/abs/0905.0111 , 227kb)
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arXiv:0905.0158
Date: Fri, 1 May 2009 23:12:14 GMT (338kb)
Title: Is state tomography an unambiguous test of quantum entanglement?
Authors: Niels Gr{\o}nbech-Jensen and Jeffrey E. Marchese and Matteo Cirillo
and James A. Blackburn
Categories: cond-mat.supr-con cond-mat.stat-mech
Comments: Four pages, two figures
\\
We provide an alternative interpretation of recently published experimental
results that were represented as demonstrating entanglement between two
macroscopic quantum Josephson oscillators. We model the experimental system
using the well-established classical equivalent circuit of a resistively and
capacitively shunted junction. Simulation results are used to generate the
corresponding density matrix, which is strikingly similar to the previously
published matrix that has been declared to be an unambiguous demonstration of
quantum entanglement. Since our data are generated by a classical model, we
therefore submit that state tomography cannot be used to determine absolutely
whether or not quantum entanglement has taken place. Analytical arguments are
given for why the classical analysis provides an adequate explanation of the
experimental results.
\\ ( http://arxiv.org/abs/0905.0158 , 338kb)
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arXiv:0905.0222
Date: Sat, 2 May 2009 17:41:42 GMT (9kb)
Title: Pairing, off-diagonal long-range order, and quantum phase transition in
strongly attracting ultracold Bose gas mixtures in tight waveguides
Authors: M.D. Girardeau
Categories: cond-mat.quant-gas cond-mat.other
Comments: 4 pages, no figures, revtex4. Submitted to PRL
\\
A model of two 1D ideal Bose gases A and B with strong AB attractions induced
by a p-wave AB Feshbach resonance is studied. The model is solved exactly by a
Bose-Bose duality mapping, and it is shown that there is no A-component or
B-component Bose-Einstein condensation and no AB-pair off-diagonal long-range
order (ODLRO), but both AA-pair and BB-pair ODLRO. After generalization by
adding even-wave AA and BB repulsion and reducing the strength of the odd-wave
AB attraction by Feshbach resonance detuning, a quantum phase transition occurs
between a phase with AB contact nodes and one with no such nodes.
\\ ( http://arxiv.org/abs/0905.0222 , 9kb)
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arXiv:0905.0257
Date: Sun, 3 May 2009 11:52:07 GMT (131kb)
Title: Hybridization and excitation of second sound in a trapped Fermi gas at
unitarity
Authors: E. Taylor, H. Hu, X.-J. Liu, L. P. Pitaevskii, A. Griffin, S.
Stringari
Categories: cond-mat.quant-gas
Comments: 4 pages, 2 figures
\\
Using a variational approach, we solve the equations of two-fluid
hydrodynamics in a unitary Fermi gas trapped by a harmonic potential. We show
that the in-phase density oscillations (first sound) weakly couple to
out-of-phase entropy oscillations (second sound) of the system, giving rise to
a typical hybridization effect where the frequencies cross. We predict the
value of the frequency splitting caused by hybridization and show how the
coupling results in a beating effect in the density response. This gives a
promising way of exciting and detecting second sound in this system.
\\ ( http://arxiv.org/abs/0905.0257 , 131kb)
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arXiv:0905.0343
Date: Mon, 4 May 2009 10:10:12 GMT (229kb)
Title: The role of spatial inhomogeneity in dissociation of trapped molecular
condensates
Authors: Magnus Ogren and K. V. Kheruntsyan
Categories: cond-mat.quant-gas
Comments: 18 pages, 10 figures
\\
We theoretically analyze dissociation of a harmonically trapped Bose-Einstein
condensate of molecular dimers and examine how the spatial inhomogeneity of the
molecular condensate affects the conversion dynamics and the atom-atom pair
correlations in the short-time limit. Both fermionic and bosonic statistics of
the constituent atoms are considered. Using the undepleted molecular field
approximation, we obtain explicit analytic results for the asymptotic behavior
of the second-order correlation functions and relative number squeezing between
the dissociated atoms in one, two and three spatial dimensions. Comparison with
the numerical results shows that the analytic approach employed here captures
the main underlying physics and provides useful insights into the dynamics of
dissociation for conversion efficiencies less than 10%. The results show
explicitly how the strength of atom-atom correlations and relative number
squeezing degrade with a decrease of the size of the molecular condensate.
\\ ( http://arxiv.org/abs/0905.0343 , 229kb)
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arXiv:0905.0386
Date: Mon, 4 May 2009 09:23:47 GMT (4173kb)
Title: The physics of dipolar bosonic quantum gases
Authors: T Lahaye, C Menotti, L Santos, M Lewenstein and T Pfau
Categories: cond-mat.quant-gas
Comments: Review article, 71 pages, 35 figures, 350 references. Submitted to
Reports on Progress in Physics
\\
This article reviews the recent theoretical and experimental advances in the
study of ultracold gases made of bosonic particles interacting via the
long-range, anisotropic dipole-dipole interaction, in addition to the
short-range and isotropic contact interaction usually at work in ultracold
gases. The specific properties emerging from the dipolar interaction are
emphasized, from the mean-field regime valid for dilute Bose-Einstein
condensates, to the strongly correlated regimes reached for dipolar bosons in
optical lattices.
\\ ( http://arxiv.org/abs/0905.0386 , 4173kb)
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arXiv:0905.0448
Date: Mon, 4 May 2009 18:22:54 GMT (408kb,D)
Title: Three-body Casimir effects and non-monotonic forces
Authors: P. Rodriguez-Lopez, S. J. Rahi, T. Emig
Categories: cond-mat.stat-mech
Comments: 4 pages, 4 figures
\\
Casimir interactions are not pair-wise additive. This property leads to
collective effects that we study for a pair of objects near a conducting wall.
We employ a scattering approach to compute the interaction in terms of
fluctuating multipoles. The wall can lead to a non-monotonic force between the
objects. For two atoms with anisotropic electric and magnetic dipole
polarizabilities we demonstrate that this non-monotonic effect results from a
competition between two- and three body interactions. By including higher order
multipoles we obtain the force between two macroscopic metallic spheres for a
wide range of sphere separations and distances to the wall.
\\ ( http://arxiv.org/abs/0905.0448 , 408kb)
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arXiv:0905.0151
Date: Fri, 1 May 2009 21:12:31 GMT (15kb)
Title: Creating and observing N-partite entanglement with atoms
Authors: Mark S. Everitt, Martin L. Jones, Benjamin T. H. Varcoe, Jacob A.
Dunningham
Categories: quant-ph
Comments: 4 pages, 1 figure
\\
The Mermin inequality provides a criterion for experimentally ruling out
local-realistic descriptions of multiparticle systems. A violation of this
inequality means that the particles must be entangled, but does not, in
general, indicate whether N-partite entanglement is present. For this, a
stricter bound is required. Here we discuss this bound and use it to propose a
scheme for demonstrating N-partite entanglement with Rydberg atoms in microwave
cavities.
\\ ( http://arxiv.org/abs/0905.0151 , 15kb)
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arXiv:0905.0159
Date: Fri, 1 May 2009 22:43:40 GMT (1572kb,D)
Title: Superfluid turbulence from quantum Kelvin wave to classical Kolmogorov
cascades
Authors: Jeffrey Yepez
Categories: quant-ph
Comments: 4 pages, 2 figures
\\
A novel unitary quantum lattice gas algorithm is used to simulate quantum
turbulence of a BEC described by the Gross-Pitaevskii equation on grids up to
57603. For the first time, an accurate power law scaling for the quantum
Kelvin wave cascade is determined: k^{-3}. The incompressible kinetic energy
spectrum exhibits very distinct power law spectra in 3 ranges of k-space: a
classical Kolmogorov k^{-5/3} spectrum at scales much greater than the
individual quantum vortex cores, and a quantum Kelvin wave cascade spectrum
k^{-3} on scales of order the vortex cores. In the semiclassical regime between
these two spectra there is a pronounced steeper spectral decay, with
non-universal exponent. The Kelvin k^{-3} spectrum is very robust, even on
small grids, while the Kolmogorov k^{-5/3} spectrum becomes more and more
apparent as the grids increase from 20483 grids to 57603.
\\ ( http://arxiv.org/abs/0905.0159 , 1572kb)
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arXiv:0905.0286
Date: Sun, 3 May 2009 20:14:33 GMT (966kb,D)
Title: Suppression of collisional decoherence
Authors: Yoav Sagi, Ido Almog and Nir Davidson
Categories: quant-ph
Comments: 4 pages, 5 figures
\\
High density ensembles of cold atoms can be used as quantum memory devices,
but often suffer from {a} high collision rate that leads to rapid decoherence.
We present a novel method to suppress this decoherence mechanism using a
continuous strong echo pulse, achieving a thirty-fold increase in the coherence
time of cold 87Rb atoms trapped in a dipole trap. Coherence times of more than
100ms are demonstrated for an ensemble with OD>100.
\\ ( http://arxiv.org/abs/0905.0286 , 966kb)
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arXiv:0905.0378
Date: Sat, 25 Apr 2009 00:58:37 GMT (1674kb,D)
Title: Invisibility of quantum systems to tunneling of matter waves
Authors: Sergio Cordero and Gaston Garcia-Calderon
Categories: quant-ph
\\
We show that an appropriate choice of the potential parameters in
one-dimensional quantum systems allows for unity transmission of the tunneling
particle at all incident tunneling energies, except at controllable exceedingly
small incident energies. The corresponding dwell time and the transmission
amplitude are indistinguishable from those of a free particle in the
unity-transmission regime. This implies the possibility of designing quantum
systems that are invisible to tunneling by a passing wave packet.
\\ ( http://arxiv.org/abs/0905.0378 , 1674kb)
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arXiv:0905.0426
Date: Mon, 4 May 2009 17:05:30 GMT (33kb)
Title: The most generalized analytical approximation to the solution of
single-mode spin-boson model without rotating-wave approximation
Authors: T. Liu, K. L. Wang, and M. Feng
Categories: quant-ph
Comments: 3 figures
\\
The single-mode spin-boson model (SMSBM) has extensive application in
different subfields of physics. In the absence of rotating-wave approximation
(RWA), we try to solve SMSBM analytically. We argue that the analytical
expression obtained is the most exact approximation to the solution of the
system under the assumption of Abel-Ruffini theorem, which works for a wide
range of the parameters such as coupling strength and detuning and would be
practical for currently available experiments.
\\ ( http://arxiv.org/abs/0905.0426 , 33kb)
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arXiv:0905.0601
Date: Tue, 5 May 2009 13:22:13 GMT (49kb)
Title: Superradiant and Dark Exciton States in an Optical Lattice within a
Cavity
Authors: Hashem Zoubi, and Helmut Ritsch
Categories: quant-ph
Comments: 4 pages, 11 figures
\\
We study ultracold atoms in a finite size one-dimensional optical lattice
prepared in the Mott insulator phase and commonly coupled to a single cavity
mode. Due to resonance dipole-dipole interactions among the atoms, electronic
excitations delocalize and form {\it excitons}. These exciton modes are divided
into two groups: antisymmetric modes which decouple from the cavity mode
forming {\it dark states}, and symmetric modes significantly coupled to the
cavity mode called {\it bright states}. In typical setups the lowest and most
symmetric exciton is coupled to the cavity photons much stronger than the other
bright states and dominates the optical properties response of the atoms ({\it
superradiant state}). In the strong coupling regime this superradiant state is
coherently mixed with the cavity photon to form a doublet of polariton states
with the Rabi splitting.
\\ ( http://arxiv.org/abs/0905.0601 , 49kb)
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arXiv:0905.0711
Date: Tue, 5 May 2009 21:47:56 GMT (346kb)
Title: Quantum dynamics of cavity assisted photoassociation of Bose-Einstein
condensed atoms
Authors: Christopher P. Search, J. Mauricio Campuzano, and Marko Zivkovic
Categories: cond-mat.quant-gas
\\
We explore the quantum dynamics of photoassociation of Bose-Einstein
condensed atoms into molecules using an optical cavity field. Inside of an
optical resonator, photoassociation of quantum degenerate atoms involves the
interaction of three coupled quantum fields for the atoms, molecules, and the
photons. The feedback created by a high-Q optical cavity causes the cavity
field to become a dynamical quantity whose behavior is linked in a nonlinear
manner to the atoms inside and where vacuum fluctuations have a more important
role than in free space. We develop and compare several methods for calculating
the dynamics of the atom-molecule conversion process with a coherently driven
cavity field. We first introduce an alternate operator representation for the
Hamiltonian from which we derive an improved form of mean field theory and an
approximate solution of the Heisenberg-Langevin (HL) equations that properly
accounts for quantum noise in the cavity field. It is shown that our improved
mean field theory corrects several deficiencies in traditional mean field
theory based on expectation values of annihilation/creation operators. Also, we
show by direct comparison to numerical solutions of the density matrix
equations that our approximate quantum solution of HL equations gives an
accurate description of weakly or undriven cavities where mean field theories
break down.
\\ ( http://arxiv.org/abs/0905.0711 , 346kb)
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arXiv:0905.0817
Date: Wed, 6 May 2009 12:21:25 GMT (6kb)
Title: Probing superfluidity of periodically trapped ultracold atoms in a
cavity by transmission spectroscopy
Authors: Aranya B.Bhattacherjee, Tarun Kumar and ManMohan
Categories: cond-mat.quant-gas quant-ph
Comments: 3 pages
\\
We study a system of periodic Bose condensed atoms coupled to cavity photons
using the input-output formalism. We show that the cavity will either act as a
through pass Lorentzian filter when the superfluid fraction of the condensate
is minimum or completely reflect the input field when the superfluid fraction
is maximum. We show that by monitoring the ratio between the transmitted field
and the reflected field, one can estimate the superfluid fraction.
\\ ( http://arxiv.org/abs/0905.0817 , 6kb)
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arXiv:0905.0824
Date: Wed, 6 May 2009 13:31:06 GMT (752kb)
Title: Probing quasi-particle states in strongly interacting atomic gases by
momentum-resolved Raman photoemission spectroscopy
Authors: Tung-Lam Dao, Iacopo Carusotto and Antoine Georges
Categories: cond-mat.quant-gas cond-mat.str-el
Comments: 10 pages, 10 figures
\\
We investigate a momentum-resolved Raman spectroscopy technique which is able
to probe the one-body spectral function and the quasi-particle states of a gas
of strongly interacting ultracold atoms. This technique is inspired by
Angle-Resolved Photo-Emission Spectroscopy, a powerful experimental probe of
electronic states in solid-state systems. Quantitative examples of
experimentally accessible spectra are given for the most significant regimes
along the BEC-BCS crossover. When the theory is specialized to RF spectroscopy,
agreement is found with recent experimental data. The main advantages of this
Raman spectroscopy over existing techniques are pointed out.
\\ ( http://arxiv.org/abs/0905.0824 , 752kb)
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arXiv:0905.0886
Date: Wed, 6 May 2009 18:39:06 GMT (2960kb,D)
Title: Quantum algorithm for Bose-Einstein condensate quantum fluid dynamics
Authors: Jeffrey Yepez and George Vahala and Linda Vahala
Categories: cond-mat.quant-gas quant-ph
Comments: 10 pages, 6 figures
Journal-ref: SPIE Quantum Information and Computation VII, Vol. 7342-21, 73420M
(2009)
DOI: 10.1117/12.819005
\\
The dynamics of vortex solitons in a BEC superfluid is studied. A quantum
lattice-gas algorithm (localization-based quantum computation) is employed to
examine the dynamical behavior of vortex soliton solutions of the
Gross-Pitaevskii equation (phi4 interaction nonlinear Schroedinger equation).
Quantum turbulence is studied in large grid numerical simulations: Kolmogorov
spectrum associated with a Richardson energy cascade occurs on large flow
scales. At intermediate scales a k^{-6} power law emerges, in a
classical-quantum transition from vortex filament reconnections to Kelvin
wave-acoustic wave coupling. The spontaneous exchange of intermediate vortex
rings is observed. Finally, at very small spatial scales a k^{-3} power law
emerges, characterizing fluid dynamics occurring within the scale size of the
vortex cores themselves, a characteristic Kelvin wave cascade region. Poincare
recurrence is studied: in the free non-interacting system, a fast Poincare
recurrence occurs for regular arrays of line vortices. The recurrence period is
used to demarcate dynamics driving the nonlinear quantum fluid towards
turbulence, since fast recurrence is an approximate symmetry of the nonlinear
quantum fluid at early times. This class of quantum algorithms is useful for
studying BEC superfluid dynamics over a broad range of wave numbers, from
quantum flow to a pseudo-classical inviscid flow regime to a Kolmogorov
inertial subrange.
\\ ( http://arxiv.org/abs/0905.0886 , 2960kb)
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arXiv:0905.0772
Date: Wed, 6 May 2009 08:20:03 GMT (895kb)
Title: Ultracold three-body collisions near overlapping Feshbach resonances
Authors: J. P. D'Incao and B. D. Esry
Categories: physics.atom-ph
Comments: 4 pages, 3 figures, 1 table
\\
We present a comprehensive collection of ultracold three-body collisions
properties near overlapping Feshbach resonances. Our results incorporate
variations of all scattering lengths and demonstrate novel collisional
behavior, such as atom-molecule interference effects. Taking advantage of the
unique ways in which these collisions reflect Efimov physics, new pathways to
control atomic and molecular losses open up. Further, we show that overlapping
resonances can greatly improve the chances of observing multiple Efimov
features in an ultracold quantum gas for nearly any system.
\\ ( http://arxiv.org/abs/0905.0772 , 895kb)
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arXiv:0905.0777
Date: Wed, 6 May 2009 12:53:31 GMT (2360kb)
Title: Integrated magneto-optical traps on a chip
Authors: S. Pollock, J. P. Cotter, A. Laliotis and E. A. Hinds
Categories: physics.atom-ph
Comments: 3 pages, 3 figures
\\
We have integrated magneto-optical traps (MOTs) into an atom chip by etching
pyramids into a silicon wafer. These have been used to trap atoms on the chip,
directly from a room temperature vapor of rubidium. This new atom trapping
method provides a simple way to integrate several atom sources on the same
chip. It represents a substantial advance in atom chip technology and offers
new possibilities for atom chip applications such as integrated single atom or
photon sources and molecules on a chip.
\\ ( http://arxiv.org/abs/0905.0777 , 2360kb)
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arXiv:0905.0902
Date: Wed, 6 May 2009 20:00:43 GMT (167kb)
Title: Exact quantum dynamics of a bosonic Josephson junction
Authors: Kaspar Sakmann, Alexej I. Streltsov, Ofir E. Alon, and Lorenz S.
Cederbaum
Categories: cond-mat.quant-gas cond-mat.other
Comments: 11 pages, 3 figures
\\
The quantum dynamics of a one-dimensional bosonic Josephson junction is
studied by solving the time-dependent many-boson Schr\"odinger equation
numerically exactly. Already for weak interparticle interactions and on short
time scales, the commonly-employed mean-field and many-body methods are found
to deviate substantially from the exact dynamics. The system exhibits rich
many-body dynamics like enhanced tunneling and a novel equilibration phenomenon
of the junction depending on the interaction, attributed to a quick loss of
coherence.
\\ ( http://arxiv.org/abs/0905.0902 , 167kb)
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arXiv:0905.0912
Date: Wed, 6 May 2009 20:40:14 GMT (214kb)
Title: Non-equilibrium Enhancement of Cooper Pairing in Cold Fermion Systems
Authors: Andrew Robertson and Victor Galitski
Categories: cond-mat.quant-gas cond-mat.supr-con
Comments: 4 pages, 3 figures
\\
Non-equilibrium stimulation of superfluidity in trapped Fermi gases is
discussed by analogy to the work of Eliashberg [G. M. Eliashberg, in
"Nonequilibrium Superconductivity," edited by D. N. Langenberg and A. I. Larkin
(North-Holland, New York, 1986)] on the microwave enhancement of
superconductivity. Optical excitation of the fermions balanced by heat loss due
to thermal contact with a boson bath and/or evaporative cooling enables
stationary non-equilibrium states to exist. Such a state manifests as a shift
of the quasiparticle spectrum to higher energies and this effect effectively
raises the pairing transition temperature. As an illustration, we calculate the
effective enhancement of Cooper pairing and superfluidity in both the normal
and superfluid phases for a mixture of Rb and Li in the limit of small
departure from equilibrium. It is argued that in experiment the desirable
effect is not limited to such small perturbations and the effective enhancement
of the pairing temperature may be quite large.
\\ ( http://arxiv.org/abs/0905.0912 , 214kb)
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arXiv:0905.0995
Date: Thu, 7 May 2009 10:53:52 GMT (261kb)
Title: Soliton dynamics at an interface between uniform medium and nonlinear
optical lattice
Authors: Fatkhulla Kh. Abdullaev, Ravil M. Galimzyanov, Marijana Brtka and
Lauro Tomio
Categories: cond-mat.quant-gas cond-mat.other
\\
We study trapping and propagation of a matter-wave soliton through the
interface between uniform medium and a nonlinear optical lattice (NOL).
Different regimes for transmission of a broad and a narrow soliton are
investigated. Reflections and transmissions of solitons are predicted as
function of the lattice phase. The existence of a threshold in the amplitude of
the nonlinear optical lattice, separating the transmission and reflection
regimes, is verified. The localized nonlinear surface state, corresponding to
the soliton trapped by the interface, is found. Variational approach
predictions are confirmed by numerical simulations for the original
Gross-Pitaevskii equation with nonlinear periodic potentials.
\\ ( http://arxiv.org/abs/0905.0995 , 261kb)
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arXiv:0905.1004
Date: Thu, 7 May 2009 11:32:35 GMT (515kb)
Title: Decoherence and entanglement in a bosonic Josephson junction:
Bose-enhanced quantum-Zeno control of phase-diffusion
Authors: Y. Khodorkovsky, G. Kurizki, and A. Vardi
Categories: cond-mat.quant-gas
Comments: 13 pages, 12 figures
\\
We study the effect of decoherence on dynamical phase diffusion in the
two-site Bose-Hubbard model. Starting with an odd parity excited coherent
state, the initial loss of single particle coherence varies from small bound
oscillations in the Rabi regime, through hyperbolic depletion in the Josephson
regime, to a Gaussian decay in the Fock regime. The inclusion of local-site
noise, measuring the relative number difference between the modes, is shown to
enhance phase-diffusion. In comparison, site-indiscriminate noise measuring the
population imbalance between the two quasi-momentum modes, slows down the loss
of single-particle coherence. Decoherence thus either enhances or suppresses
phase-diffusion, depending on the details of system-bath coupling and the
overlap of decoherence pointer states with collisional-entanglement pointer
states. The deceleration of phase-diffusion due to the coupling with the
environment may be viewed as a many-body quantum-Zeno effect. The extended
effective decay times in the presence of projective measurement, are further
enhanced with increasing number of particles $N$, by a bosonic factor of
$\sqrt{N}$ in the Fock regime and $N/\log{N}$ in the Josephson regime.
\\ ( http://arxiv.org/abs/0905.1004 , 515kb)
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arXiv:0905.1023
Date: Thu, 7 May 2009 13:09:27 GMT (71kb)
Title: The induced interaction in a Fermi gas with a BEC-BCS crossover
Authors: Zeng-Qiang Yu, Kun Huang, Lan Yin
Categories: cond-mat.quant-gas cond-mat.supr-con
Comments: 11 pages, 3 figures, to be published in PRA
\\
We study the effect of the induced interaction on the superfluid transition
temperature of a Fermi gas with a BEC-BCS crossover. The
Gorkov-Melik-Barkhudarov theory about the induced interaction is extended from
the BCS side to the entire crossover, and the pairing fluctuation is treated in
the approach by Nozi\`{e}res and Schmitt-Rink. At unitarity, the induced
interaction reduces the transition temperature by about twenty percent. In the
BCS limit, the transition temperature is reduced by a factor about 2.22, as
found by Gorkov and Melik-Barkhudarov. Our result shows that the effect of the
induced interaction is important both on the BCS side and in the unitary
region.
\\ ( http://arxiv.org/abs/0905.1023 , 71kb)
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arXiv:0905.1063
Date: Thu, 7 May 2009 17:52:32 GMT (317kb)
Title: A high-flux 2D MOT source for cold lithium atoms
Authors: T.G. Tiecke, S.D. Gensemer, A. Ludewig, and J.T.M. Walraven
Categories: cond-mat.quant-gas
Comments: 13 pages,9 figures, submitted to Phys.Rev.A
\\
We demonstrate a novel 2D MOT beam source for cold 6Li atoms. The source is
side-loaded from an oven operated at temperatures in the range 600<T<700 K. The
performance is analyzed by loading the atoms into a 3D MOT located 220 mm
downstream from the source. The maximum recapture rate of ~109 /s is obtained
for T=700 K and results in a total of up to 1010 trapped atoms. The recaptured
fraction is estimated to be 30(10)% and limited by beam divergence. The
most-probable velocity in the beam (alpha_z) is varied from 18 to 70 m/s by
increasing the intensity of a push beam. The source is quite monochromatic with
a full-width at half maximum velocity spread of 11 m/s at alpha_z=36 m/s,
demonstrating that side-loading completely eliminates beam contamination by hot
vapor from the oven. We identify depletion of the low-velocity tail of the oven
flux as the limiting loss mechanism. Our approach is suitable for other atomic
species.
\\ ( http://arxiv.org/abs/0905.1063 , 317kb)
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arXiv:0905.0931
Date: Thu, 7 May 2009 16:29:48 GMT (1446kb)
Title: Amplified Quantum Dynamics and Enhanced Parameter Sensitivity via
Coherent Feedback in Collective Atomic Spin Systems
Authors: Bradley A. Chase and JM Geremia
Categories: quant-ph
Comments: 28 Pages with 6 Figures. Please visit http://qmc.phys.unm.edu to
download C++ class files, mex/Matlab source code, and data files used to
generate all simulation data and figures in this paper as well as precompiled
mex libraries for the Windows x64 and intel Mac platforms
\\
We consider the effective dynamics obtained by double-passing a far-detuned
laser probe through a large atomic spin system. The net result of the
atom-field interaction is a type of coherent positive feedback that amplifies
the values of selected spin observables. An effective equation of motion for
the atomic system is presented, and an approximate 2-parameter model of the
dynamics is developed that should provide a viable approach to modeling even
the extremely large spin systems, with N>>1 atoms, encountered under typical
laboratory conditions.
Combining the nonlinear dynamics that result from the positive feedback with
continuous observation of the atomic spin offers an improvement in quantum
parameter estimation. We explore the possibility of reaching the Heisenberg
uncertainty scaling in atomic magnetometry without the need for any appreciable
spin-squeezing by analyzing our system via the quantum Cramer-Rao inequality.
Finally, we develop a realistic quantum parameter estimator for atomic
magnetometry that is based on a two-parameter family of Gaussian states and
investigate the performance of this estimator through numerical simulations. In
doing so, we identify several issues, such as numerical convergence and the
reduction of estimator bias, that must be addressed when incorporating our
parameter estimation methods into an actual laboratory setting.
\\ ( http://arxiv.org/abs/0905.0931 , 1446kb)
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\\
arXiv:0905.0970
Date: Thu, 7 May 2009 08:56:20 GMT (1279kb)
Title: Multi-Stability of Electromagnetically Induced Transparency in
Atom-Assisted Optomechanical Cavities
Authors: Yue Chang, T. Shi, Yu-xi Liu, C. P. Sun, and Franco Nori
Categories: quant-ph
Comments: 10 pages, 9 figures
\\
We study how an oscillating mirror affects the electromagnetically induced
transparency (EIT) of an atomic ensemble, which is confined in a gas cell
placed inside a micro-cavity with an oscillating mirror in one end. The
oscillating mirror is modeled as a quantum mechanical harmonic oscillator. The
cavity field acts as a probe light of the EIT system and also produces a light
pressure on the oscillating mirror. The back-action from the mirror to the
cavity field results in several (from one to five) steady-states for this
atom-assisted optomechanical cavity, producing a complex structure in its EIT.
We calculate the susceptibility with respect to the few (from one to three)
stable solutions found here for the equilibrium positions of the oscillating
mirror. We find that the EIT of the atomic ensemble can be significantly
changed by the oscillating mirror, and also that the various steady states of
the mirror have different effects on the EIT.
\\ ( http://arxiv.org/abs/0905.0970 , 1279kb)
------------------------------------------------------------------------------
\\
arXiv:0905.0958
Date: Thu, 7 May 2009 07:32:19 GMT (1118kb)
Title: Line shapes of optical Feshbach resonances near the intercombination
transition of bosonic Ytterbium
Authors: M. Borkowski, R. Ciurylo, P. S. Julienne, S. Tojo, K. Enomoto, Y.
Takahashi
Categories: physics.atom-ph
\\
The properties of bosonic Ytterbium photoassociation spectra near the
intercombination transition $^{1}S_{0}$--$^{3}P_{1}$ are studied theoretically
at ultra low temperatures. We demonstrate how the shapes and intensities of
rotational components of optical Feshbach resonances are affected by mass
tuning of the scattering properties of the two colliding ground state atoms.
Particular attention is given to the relationship between the magnitude of the
scattering length and the occurrence of shape resonances in higher partial
waves of the van der Waals system. We develop a mass scaled model of the
excited state potential that represents the experimental data for different
isotopes. The shape of the rotational photoassociation spectrum for various
bosonic Yb isotopes can be qualitatively different.
\\ ( http://arxiv.org/abs/0905.0958 , 1118kb)
------------------------------------------------------------------------------
The replacements:
------------------------------------------------------------------------------
\\
arXiv:0811.2798
replaced with revised version Sat, 2 May 2009 08:13:46 GMT (641kb)
Title: Probing condensate order in deep optical lattices
Authors: Kuei Sun, Courtney Lannert, Smitha Vishveshwara
Categories: cond-mat.other
Comments: 15 pages, 9 figures, RevTeX; content changed, references changed
Journal-ref: Phys. Rev. A 79, 043422 (2009)
DOI: 10.1103/PhysRevA.79.043422
\\ ( http://arxiv.org/abs/0811.2798 , 641kb)
------------------------------------------------------------------------------
\\
arXiv:0812.0266
replaced with revised version Mon, 4 May 2009 18:50:40 GMT (495kb)
Title: Threshold of a Random Laser with Cold Atoms
Authors: Luis S. Froufe-P\'erez, William Guerin (INLN), R\'emi Carminati
(LPEM), Robin Kaiser (INLN)
Categories: physics.atom-ph cond-mat.dis-nn physics.optics
Journal-ref: Physical Review Letters 102 (2009) 173903
\\ ( http://arxiv.org/abs/0812.0266 , 495kb)
------------------------------------------------------------------------------
\\
arXiv:0812.1581
replaced with revised version Fri, 1 May 2009 20:11:11 GMT (1998kb)
Title: Superconductivity close to the Mott state: From condensed-matter systems
to superfluidity in optical lattices
Authors: Karyn Le Hur and T. Maurice Rice
Categories: cond-mat.supr-con cond-mat.str-el
Comments: 98 pages and 18 figures; Final version (references added and
misprints corrected)
\\ ( http://arxiv.org/abs/0812.1581 , 1998kb)
------------------------------------------------------------------------------
\\
arXiv:0902.2427
replaced with revised version Mon, 4 May 2009 18:44:32 GMT (125kb)
Title: Bistable Mott-insulator to superfluid phase transition in cavity
optomechanics
Authors: W. Chen, K. Zhang, D. S. Goldbaum, M. Bhattacharya, P. Meystre
Categories: quant-ph cond-mat.other
Comments: 5 pages, 3 figures
\\ ( http://arxiv.org/abs/0902.2427 , 125kb)
------------------------------------------------------------------------------
\\
arXiv:0904.3131
replaced with revised version Mon, 4 May 2009 13:46:36 GMT (206kb)
Title: Fortran programs for the time-dependent Gross-Pitaevskii equation in a
fully anisotropic trap
Authors: P. Muruganandam and S. K. Adhikari
Categories: cond-mat.quant-gas nlin.PS physics.comp-ph
Comments: 34 pages, 11 figures, 18 Fortran programs included, output files (not
included) available in Comput. Phys. Commun. Library after publication
\\ ( http://arxiv.org/abs/0904.3131 , 206kb)
------------------------------------------------------------------------------
\\
arXiv:0904.4474
replaced with revised version Mon, 4 May 2009 15:08:36 GMT (49kb)
Title: Collective modes and superflow instabilities of strongly correlated
Fermi superfluids
Authors: R. Ganesh, A. Paramekanti, A. A. Burkov
Categories: cond-mat.supr-con cond-mat.quant-gas
Comments: 14 pages, 10 figures. Corrected 3d phase diagram
\\ ( http://arxiv.org/abs/0904.4474 , 49kb)
------------------------------------------------------------------------------
\\
arXiv:0904.4862
replaced with revised version Mon, 4 May 2009 11:13:35 GMT (10kb)
Title: A quantum de Finetti theorem in phase space representation
Authors: Anthony Leverrier, Nicolas J. Cerf
Categories: quant-ph
Comments: 5 pages
\\ ( http://arxiv.org/abs/0904.4862 , 10kb)
------------------------------------------------------------------------------
\\
arXiv:0811.2219
replaced with revised version Tue, 5 May 2009 20:26:38 GMT (192kb)
Title: State diagrams for harmonically trapped bosons in optical lattices
Authors: Marcos Rigol, George G. Batrouni, Valery G. Rousseau, Richard T.
Scalettar
Categories: cond-mat.other cond-mat.stat-mech
Comments: 10 pages, 11 figures, published version
Journal-ref: Phys. Rev. A 79, 053605 (2009)
DOI: 10.1103/PhysRevA.79.053605
\\ ( http://arxiv.org/abs/0811.2219 , 192kb)
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\\
arXiv:0807.3358
replaced with revised version Thu, 7 May 2009 12:32:27 GMT (2323kb,D)
Title: Quantum interface between light and atomic ensembles
Authors: K. Hammerer, A.S. Sorensen, E.S. Polzik
Categories: quant-ph cond-mat.other
Comments: 56 pages, 22 figures, 3.3MB; to be published in Reviews of Modern
Physics; completely revised, final version
\\ ( http://arxiv.org/abs/0807.3358 , 2323kb)
------------------------------------------------------------------------------
\\
arXiv:0904.3376
replaced with revised version Thu, 7 May 2009 07:17:05 GMT (246kb)
Title: Stability and chaotic behavior of Bose-Einstein condensates in optical
lattices with two- and three-body interactions
Authors: Yan Chen, Ke-Zhi Zhang, and Yong Chen
Categories: cond-mat.quant-gas
Comments: 11 pages, 6 figures
\\ ( http://arxiv.org/abs/0904.3376 , 246kb)
------------------------------------------------------------------------------
\\
arXiv:0904.2515
replaced with revised version Thu, 7 May 2009 11:47:06 GMT (130kb)
Title: Collisional losses, decoherence, and frequency shifts in optical lattice
clocks with bosons
Authors: Ch. Lisdat, J.S.R. Vellore Winfred, T. Middelmann, F. Riehle, U. Sterr
Categories: physics.atom-ph
Comments: 4 pages, 3 figures
\\ ( http://arxiv.org/abs/0904.2515 , 130kb)
------------------------------------------------------------------------------
Till next time,
Matt.
--
=========================================================================
Dr M. J. Davis, Associate Professor in Physics
School of Mathematics and Physics, ph : +61 7 334 69824
The University of Queensland, fax : +61 7 336 51242
Brisbane, QLD 4072, mdavis_at_physics.uq.edu.au
Australia. 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/
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Received on Tue Jun 16 2009 - 10:27:50 EST
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