# [Matts-arxiv] Matt's arXiv selection: week ending 9 July 2010

From: Matthew Davis <mdavis_at_physics.uq.edu.au>
Date: Wed, 1 Sep 2010 09:57:15 +1000

Dear subscribers,

This week's selection was compiled by Simon Haine, and contains 42 new abstracts
and 8 replacements.

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arXiv:1006.0739
Date: Thu, 3 Jun 2010 20:29:57 GMT (311kb,D)

Title: Realization of an Excited, Strongly-Correlated Quantum Gas Phase
Authors: Elmar Haller, Mattias Gustavsson, Manfred J. Mark, Johann G. Danzl,
Russell Hart, Guido Pupillo, Hanns-Christoph N\"agerl
Categories: cond-mat.quant-gas
Journal-ref: Science 325, 1224 (2009)
\\
Ultracold atomic physics offers myriad possibilities to study strongly
correlated many-body systems in lower dimensions. Typically, only ground state
phases are accessible. Using a tunable quantum gas of bosonic cesium atoms, we
realize and control in one dimensional geometry a highly excited quantum phase
that is stabilized in the presence of attractive interactions by maintaining
and strengthening quantum correlations across a confinement-induced resonance.
We diagnose the crossover from repulsive to attractive interactions in terms of
the stiffness and the energy of the system. Our results open up the
experimental study of metastable excited many-body phases with strong
correlations and their dynamical properties.
\\ ( http://arxiv.org/abs/1006.0739 , 311kb)
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arXiv:1006.0742
Date: Thu, 3 Jun 2010 20:54:32 GMT (4249kb)

Title: Dipole blockade in a cold Rydberg atomic sample
Authors: Daniel Comparat and Pierre Pillet
Categories: physics.atom-ph quant-ph
Comments: Similar (without Appendix) article have been published in JOSA B, 27,
A208 (2010)
Journal-ref: JOSA B, Vol. 27, Issue 6, pp. A208-A232 (2010)
DOI: 10.1364/JOSAB.27.00A208
\\
We review here the studies performed about interactions in an assembly of
cold Rydberg atoms. We focus more specially the review on the dipole-dipole
interactions and on the effect of the dipole blockade in the laser Rydberg
excitation, which offers attractive possibilities for quantum engineering. We
present first the various interactions between Rydberg atoms. The laser Rydberg
excitation of such an assembly is then described with the introduction of the
dipole blockade phenomenon. We report recent experiments performed in this
subject by starting with the case of a pair of atoms allowing the entanglement
of the wave-functions of the atoms and opening a fascinating way for the
realization of quantum bits and quantum gates. We consider then several works
on the blockade effect in a large assembly of atoms for three different
configurations: blockade through electric-field induced dipole, through
F\"orster resonance and in van der Waals interaction. The properties of
coherence and cooperativity are analyzed. Finally, we treat the role of
dipole-dipole interactions between Rydberg atoms responsible for Penning
ionization. The perturbation of the dipole blockade by ions and the evolution
of the Rydberg towards an ultracold plasma are discussed.
\\ ( http://arxiv.org/abs/1006.0742 , 4249kb)
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arXiv:1006.0754
Date: Thu, 3 Jun 2010 23:06:41 GMT (2758kb,D)

Title: Probing the Superfluid to Mott Insulator Transition at the Single Atom
Level
Authors: Waseem S. Bakr, Amy Peng, M. Eric Tai, Ruichao Ma, Jonathan Simon,
Jonathon I. Gillen, Simon Foelling, Lode Pollet, Markus Greiner
Categories: cond-mat.quant-gas quant-ph
\\
Quantum gases in optical lattices offer an opportunity to experimentally
realize and explore condensed matter models in a clean, tunable system. We
investigate the Bose-Hubbard model on a microscopic level using single
atom-single lattice site imaging; our technique enables space- and
time-resolved characterization of the number statistics across the
superfluid-Mott insulator quantum phase transition. Site-resolved probing of
fluctuations provides us with a sensitive local thermometer, allows us to
identify microscopic heterostructures of low entropy Mott domains, and enables
us to measure local quantum dynamics, revealing surprisingly fast transition
timescales. Our results may serve as a benchmark for theoretical studies of
quantum dynamics, and may guide the engineering of low entropy phases in a
lattice.
\\ ( http://arxiv.org/abs/1006.0754 , 2758kb)
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arXiv:1006.0762
Date: Fri, 4 Jun 2010 00:56:15 GMT (4272kb)

Title: Time-reversal symmetry breaking in circuit-QED based photon lattices
Authors: Jens Koch, Andrew A. Houck, Karyn Le Hur, S. M. Girvin
Categories: cond-mat.mes-hall cond-mat.other cond-mat.quant-gas
Comments: 19 pages, 13 figures, 2 tables
\\
Breaking time-reversal symmetry is a prerequisite for accessing certain
interesting many-body states such as fractional quantum Hall states. For
polaritons, charge neutrality prevents magnetic fields from providing a direct
symmetry breaking mechanism and similar to the situation in ultracold atomic
gases, an effective magnetic field has to be synthesized. We show that in the
circuit QED architecture, this can be achieved by inserting simple
superconducting circuits into the resonator junctions. In the presence of such
coupling elements, constant parallel magnetic and electric fields suffice to
break time-reversal symmetry. We support these theoretical predictions with
numerical simulations for realistic sample parameters, specify general
conditions under which time-reversal is broken, and discuss the application to
chiral Fock state transfer, an on-chip circulator, and tunable band structure
for the Kagome lattice.
\\ ( http://arxiv.org/abs/1006.0762 , 4272kb)
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arXiv:1006.0769
Date: Fri, 4 Jun 2010 02:32:08 GMT (306kb)

Title: Energy spectrum of harmonically trapped two-component Fermi gases:
Three- and Four-Particle Problem
Authors: K. M. Daily and D. Blume
Categories: cond-mat.quant-gas
Journal-ref: Phys. Rev. A. 81, 053615 (2010)
\\
Trapped two-component Fermi gases allow for the investigation of the
so-called BCS-BEC crossover by tuning the interspecies atom-atom $s$-wave
scattering length scattering $a^{(aa)}$ from attractive to repulsive, including
vanishing and infinitely large values. Here, we numerically determine the
energy spectrum of the equal-mass spin-balanced four-fermion system---the
smallest few-particle system that exhibits BCS-BEC crossover-like behavior---as
a function of $a^{(aa)}$ using the stochastic variational approach. For
comparative purposes, we also treat the two- and three-particle systems. States
with vanishing and finite total angular momentum as well as with natural and
unnatural parity are considered. In addition, the energy spectrum of
weakly-attractive and weakly-repulsive gases is characterized by employing a
perturbative framework that utilizes hyperspherical coordinates. The
hyperspherical coordinate approach allows for the straightforward assignment of
quantum numbers and furthermore provides great insights into the
strongly-interacting unitary regime.
\\ ( http://arxiv.org/abs/1006.0769 , 306kb)
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arXiv:1006.0854
Date: Fri, 4 Jun 2010 10:40:53 GMT (100kb)

Title: Collapse dynamics of a ${}^{176}\textrm{Yb}\,$-${}^{174}\textrm{Yb}$
Bose-Einstein condensate
Authors: G. K. Chaudhary and R. Ramakumar
Categories: cond-mat.quant-gas
Journal-ref: Phys. Rev. A 81, 063603 (2010)
DOI: 10.1103/PhysRevA.81.063603
\\
In this paper, we present a theoretical study of a two-component
Bose-Einstein condensate composed of Ytterbium (Yb) isotopes in a three
dimensional anisotropic harmonic potential. The condensate consists of a
mixture of ${}^{176}\textrm{Yb}$ atoms which have a negative s-wave scattering
length and ${}^{174}\textrm{Yb}$ atoms having a positive s-wave scattering
length. We study the ground state as well as dynamic properties of this
two-component condensate. Due to the attractive interactions between
${}^{176}\textrm{Yb}$ atoms, the condensate of ${}^{176}\textrm{Yb}$ undergo a
collapse when the particle number exceed a critical value. The critical number
and the collapse dynamics are modified due to the presence of
${}^{174}\textrm{Yb}$ atoms. We use coupled two-component Gross-Pitaevskii
equations to study the collapse dynamics. The theoretical results obtained are
in reasonable agreement with the experimental results of Fukuhara {\em et al.}
[PRA{\bf 79}, 021601(R) (2009)].
\\ ( http://arxiv.org/abs/1006.0854 , 100kb)
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arXiv:1006.0905 (*cross-listing*)
Date: Fri, 4 Jun 2010 14:29:00 GMT (199kb)

Title: When is it easier for a quantum particle to tunnel through than to fly
above a barrier?
Authors: Denys I. Bondar, Wing-Ki Liu, and Misha Yu. Ivanov
Categories: quant-ph physics.atom-ph physics.ed-ph
Comments: 8 pages and 6 figures
\\
We present a class of 2D systems which shows a counterintuitive property that
contradicts a semi classical intuition: a 2D quantum particle "prefers"
tunnelling through a barrier rather than travelling above it. Viewing the one
particle 2D system as the system of two 1D particles, it is demonstrated that
this effect occurs due to a specific symmetry of the barrier that forces
excitations of the interparticle degree of freedom that, in turn, leads to the
appearance of an effective potential barrier even though there is no "real"
barrier. This phenomenon cannot exist in 1D.
\\ ( http://arxiv.org/abs/1006.0905 , 199kb)
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arXiv:1006.0917
Date: Fri, 4 Jun 2010 15:06:03 GMT (217kb)

Title: Measurement of the atom number distribution in an optical tweezer using
single photon counting
Authors: A. Fuhrmanek, Y.R.P. Sortais, P. Grangier and A. Browaeys
Categories: cond-mat.quant-gas
\\
We demonstrate in this paper a method to reconstruct the atom number
distribution of a cloud containing a few tens of cold atoms. The atoms are
first loaded from a magneto-optical trap into a microscopic optical dipole trap
and then released in a resonant light probe where they undergo a Brownian
motion and scatter photons. We count the number of photon events detected on an
image intensifier. Using the response of our detection system to a single atom
as a calibration, we extract the atom number distribution when the trap is
loaded with more than one atom. The atom number distribution is found to be
compatible with a Poisson distribution.
\\ ( http://arxiv.org/abs/1006.0917 , 217kb)
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arXiv:1006.0924
Date: Fri, 4 Jun 2010 15:43:12 GMT (1083kb,D)

Title: Structure and consequences of vortex-core states in p-wave superfluids
Authors: G. Moller, N. R. Cooper, V. Gurarie
Categories: cond-mat.supr-con cond-mat.quant-gas
\\
It is now well established that in two-dimensional chiral p-wave paired
superfluids, the vortices carry zero-energy modes which obey non-abelian
exchange statistics and can potentially be used for topological quantum
computation. In such superfluids there may also exist other excitations below
the bulk gap inside the cores of vortices. We study the properties of these
subgap states, and argue that their presence affects the topological protection
of the zero modes. In conventional superconductors where the chemical potential
is of the order of the Fermi energy of a non-interacting Fermi gas, there is a
large number of subgap states and the mini-gap towards the lowest of these
states is a small fraction of the Fermi energy. It is therefore difficult to
cool the system to below the mini-gap and at experimentally available
temperatures, transitions between the subgap states, including the zero modes,
will occur and can alter the quantum states of the zero-modes. We show that
compound qubits involving the zero-modes and the parity of the occupation
number of the subgap states on each vortex are still well defined. However,
practical schemes taking into account all subgap states would nonetheless be
difficult to achieve. We propose to avoid this difficulty by working in the
regime of small chemical potential mu, near the transition to a strongly paired
phase, where the number of subgap states is reduced. We develop the theory to
describe this regime of strong pairing interactions and we show how the subgap
states are ultimately absorbed into the bulk gap. Since the bulk gap vanishes
as mu -> 0 there is an optimum value mu_c which maximises the combined gap. We
propose cold atomic gases as candidate systems where the regime of strong
interactions can be explored, and explicitly evaluate mu_c in a Feshbach
resonant K-40 gas.
\\ ( http://arxiv.org/abs/1006.0924 , 1083kb)
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arXiv:1006.0928 (*cross-listing*)
Date: Fri, 4 Jun 2010 15:45:39 GMT (28kb)

Title: Critical mass and the dependency of research quality on group size
Authors: Ralph Kenna, Bertrand Berche
Categories: physics.soc-ph cond-mat.stat-mech
Comments: 14 pages, 6 figures consisting of 16 panels
\\
Academic research groups are treated as complex systems and their cooperative
behaviour is analysed from a mathematical and statistical viewpoint. Contrary
to the naive expectation that the quality of a research group is simply given
by the mean calibre of its individual scientists, we show that intra-group
interactions play a dominant role. Our model manifests phenomena akin to phase
transitions which are brought about by these interactions, and which facilitate
the quantification of the notion of critical mass for research groups. We
present these critical masses for many academic areas. A consequence of our
analysis is that overall research performance of a given discipline is improved
by supporting medium-sized groups over large ones, while small groups must
strive to achieve critical mass.
\\ ( http://arxiv.org/abs/1006.0928 , 28kb)
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arXiv:1006.0943
Date: Fri, 4 Jun 2010 17:06:26 GMT (2498kb,D)

Title: Transfer of BECs through discrete breathers in an optical lattice
Authors: Holger Hennig, J\'er\^ome Dorignac, David K. Campbell
Categories: cond-mat.quant-gas nlin.PS
\\
We study the stability of a stationary discrete breather (DB) on a nonlinear
trimer in the framework of the discrete nonlinear Schr\"odinger equation
(DNLS). In previous theoretical investigations of the dynamics of Bose-Einstein
condensates in leaking optical lattices, collisions between a DB and a lattice
excitation, e.g. a moving breather (MB) or phonon, were studied. These
collisions lead to the transmission of a fraction of the incident (atomic) norm
of the MB through the DB, while the DB can be shifted in the direction of the
incident lattice excitation. Here we show that there exists a total energy
threshold of the trimer, above which the lattice excitation can trigger the
destabilization of the DB and that this is the mechanism leading to the
movement of the DB. Furthermore, we give an analytic estimate of upper bound to
the norm that is transmitted through the DB. Our analysis explains the results
of the earlier numerical studies and may help to clarify functional operations
with BECs in optical lattices such as blocking and filtering coherent (atomic)
beams.
\\ ( http://arxiv.org/abs/1006.0943 , 2498kb)
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arXiv:1006.0966
Date: Fri, 4 Jun 2010 19:08:48 GMT (830kb)

Title: Cold Fermi-gas with long range interaction in a harmonic trap
Authors: M. Kulkarni, A. G. Abanov
Categories: cond-mat.quant-gas cond-mat.str-el hep-th math-ph math.MP
\\
We study equilibrium density and spin density profiles for a model of cold
one-dimensional spin 1/2 fermions interacting via inverse square interaction
and exchange in an external harmonic trap. This model is the well-known
spin-Calogero model (sCM) and its fully nonlinear collective field theory
description (up to gradients) is known[1]. We extend the field theory
description to the presence of an external harmonic trap and obtain analytic
results for statics and dynamics of the system. For instance, we find how the
equilibrium density profile changes upon tuning the interaction strength. The
results we obtain for equilibrium configurations are very similar to the ones
obtained recently by Ma and Yang[2] for a different model - one-dimensional
fermions with contact interactions. Our main approximation is the neglect of
the terms of higher order in spatial derivatives in equations of motion -
gradientless approximation[1]. Within this approximation the hydrodynamic
equations of motion can be written as a set of decoupled forced Riemann-Hopf
equations for the dressed Fermi momenta of the model. This enables us to write
analytical solutions for the dynamics of spin and charge. We describe the time
evolution of the charge density when an initial non-equilibrium profile is
created by cooling the gas with an additional potential in place and then
suddenly removing the potential. We present our results as a simple
"single-particle" evolution in the phase-space reminiscing a similar
description of the dynamics of non-interacting one-dimensional fermions.
\\ ( http://arxiv.org/abs/1006.0966 , 830kb)
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arXiv:1006.0969
Date: Fri, 4 Jun 2010 19:19:16 GMT (910kb)

Title: Techniques to measure quantum criticality in cold atoms
Authors: Kaden R. A. Hazzard and Erich J. Mueller
Categories: cond-mat.quant-gas cond-mat.stat-mech cond-mat.str-el quant-ph
Comments: 12 double spaced pages (main text), 12 double spaced pages
(supplementary information), 4 figures (10 panels)
\\
Attempts to understand zero temperature phase transitions have forced
physicists to consider a regime where the standard paradigms of condensed
matter physics break down [1-4]. These quantum critical systems lack a simple
description in terms of weakly interacting quasiparticles, but over the past 20
years physicists have gained deep insights into their properties. Most
dramatically, theory predicts that universal scaling relationships describe
their finite temperature thermodynamics up to remarkably high temperatures.
Unfortunately, these universal functions are hard to calculate: for example
there are no reliable general techniques [4,5] to calculate the scaling
functions for dynamics. Viewing a cold atom experiment as a quantum simulator
[6], we show how to extract universal scaling functions from (non-universal)
atomic density profiles or spectroscopic measurements. Such experiments can
resolve important open questions about the Mott-Metal crossover [7,8] and the
dynamics of the finite density O(2) rotor model [1,9], with direct impact on
theories of, for example, high temperature superconducting cuprates [10,11],
heavy fermion materials [12], and graphene [13].
\\ ( http://arxiv.org/abs/1006.0969 , 910kb)
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arXiv:1006.1072
Date: Sat, 5 Jun 2010 21:49:52 GMT (19kb)

Title: An Example of Quantum Anomaly in the Physics of Ultra-Cold Gases
Authors: Maxim Olshanii, H\'el\ene Perrin, Vincent Lorent
Categories: cond-mat.quant-gas quant-ph
\\
In this article, we propose an experimental scheme for observation of a
quantum anomaly---quantum-mechanical symmetry breaking---in a two-dimensional
harmonically trapped Bose gas. The anomaly manifests itself in a shift of the
monopole excitation frequency away from the value dictated by the
Pitaevskii-Rosch dynamical symmetry [L. P. Pitaevskii and A. Rosch, Phys. Rev.
A, 55, R853 (1997)]. While the corresponding classical Gross-Pitaevskii
equation and the derived from it hydrodynamic equations do exhibit this
symmetry, it is---as we show in our paper---violated under quantization. The
resulting frequency shift is of the order of 1% of the carrier, well in reach
for modern experimental techniques. We propose using the dipole oscillations as
a frequency gauge.
\\ ( http://arxiv.org/abs/1006.1072 , 19kb)
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arXiv:1006.1131
Date: Sun, 6 Jun 2010 19:11:39 GMT (2434kb)

Title: Double-degenerate Bose-Fermi mixture of strontium
Authors: Meng Khoon Tey, Simon Stellmer, Rudolf Grimm, Florian Schreck
Categories: cond-mat.quant-gas
\\
We report on the attainment of a spin-polarized Fermi sea of 87-Sr in thermal
contact with a Bose-Einstein condensate (BEC) of 84-Sr. Interisotope collisions
thermalize the fermions with the bosons during evaporative cooling. A
degeneracy of T/T_F=0.30(5) is reached with 2x10^4 87-Sr atoms together with an
almost pure 84-Sr BEC of 10^5 atoms.
\\ ( http://arxiv.org/abs/1006.1131 , 2434kb)
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arXiv:1006.1174
Date: Mon, 7 Jun 2010 05:54:57 GMT (1053kb,D)

Title: Signature of Quantum Criticality in the Density Profiles of Cold Atom
Systems
Authors: Qi Zhou and Tin-Lun Ho
Categories: cond-mat.quant-gas
\\
In recent years, there is considerable experimental effort using cold atoms
to study strongly correlated many-body systems. One class of phenomena of
particularly interests is quantum critical (QC) phenomena. While prevalent in
many materials, these phenomena are notoriously difficult theoretical problems
due to the vanishing of energy scales in QC region. So far, there are no
systematic ways to deduce QC behavior of bulk systems from the data of trapped
atomic gases. Here, we present a simple algorithm to use the experimental
density profile to determine the T=0 phase boundary of bulk systems, as well as
the scaling functions in QC regime. We also present another scheme for removing
finite size effects of the trap. We demonstrate the validity of our schemes
using exactly soluble models.
\\ ( http://arxiv.org/abs/1006.1174 , 1053kb)
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arXiv:1006.1269
Date: Mon, 7 Jun 2010 15:02:55 GMT (482kb)

Title: Incompressible states of a two-component Fermi gas in a double-well
optical lattice
Authors: Fran\ccois Cr\'epin, Roberta Citro and Pascal Simon
Categories: cond-mat.quant-gas
Comments: 10 pages, 7 figures. Accepted for publication in PRA
\\
We propose a scheme to investigate the effect of frustration on the magnetic
phase transitions of cold atoms confined in an optical lattice. We also
demonstrate how to get two-leg spin ladders with frustrated spin-exchange
coupling which display a phase transition from a spin liquid to a fully
incompressible state. Various experimental quantities are further analyzed for
describing this new phase.
\\ ( http://arxiv.org/abs/1006.1269 , 482kb)
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arXiv:1006.1295
Date: Mon, 7 Jun 2010 16:46:27 GMT (745kb)

Title: Observation of a red-blue detuning asymmetry in matter-wave
Authors: L.Deng, E. W. Hagley, Qiang Cao, Xiaorui Wang, Xinyu Luo, Ruquan Wang,
Fan Yang, Xiaoji Zhou, Xuzong Chen, M. G. Payne and Mingsheng Zhan
Categories: cond-mat.quant-gas quant-ph
Comments: The original version of this manuscript was first submitted in early
March, 2010 to Physical Review A Rapid Communications
\\
We show the first experimental observations of matter-wave superradiance
using blue-detuned light, and demonstrate a pump-laser detuning asymmetry in
the collective atomic recoil motion. In contrast to all previous theoretical
treatments, which predict that the process should be symmetric with respect to
the sign of the pump-laser detuning, we find that for sufficiently high
condensate densities the symmetry is broken. However, in the limit of a dilute
atomic gas the symmetry is restored. With high atomic densities and a
red-detuned pump laser, the usual distinctive multi-order matter-wave
scattering pattern is clearly visible, whereas with blue-detuned light the
collective atom recoil motion is strongly suppressed.
\\ ( http://arxiv.org/abs/1006.1295 , 745kb)
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arXiv:1006.1336 (*cross-listing*)
Date: Mon, 7 Jun 2010 19:14:22 GMT (32kb)

Title: Generation and detection of NOON states in superconducting circuits
Authors: Seth T. Merkel and Frank K. Wilhelm
Categories: quant-ph cond-mat.supr-con
Comments: 15 pages and 3 figures
\\
NOON states, states between two modes of light of the form
$|N,0\rangle+e^{i\phi}|0,N\rangle$ allow for super-resolution interformetry. We
show how NOON states can be efficiently produced in circuit quntum
electrodynamics using superconducting phase qubits and resonators. We propose a
protocol where only one interaction between the two modes is required, creating
all the necessary entanglement at the start of the procedure. This protocol
makes active use of the first three states of the phase qubits. Additionally,
we show how to efficiently verify the success of such an experiment, even for
large NOON states, using randomly sampled measurements and semidefinite
programming techniques.
\\ ( http://arxiv.org/abs/1006.1336 , 32kb)
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arXiv:1006.1392
Date: Mon, 7 Jun 2010 22:39:24 GMT (52kb)

Title: Speed of sound in a superfluid Fermi gas in an optical lattice
Authors: Z. G. Koinov
Categories: cond-mat.str-el
\\
A system of equal mixture of $^6Li$ atomic Fermi gas of two hyperfine states
loaded into a cubic three-dimensional optical lattice is studied assuming a
negative scattering length (BCS side of the Feshbach resonance). When the
interaction is attractive, fermionic atoms can pair and form a superfluid. The
dispersion of the phonon-like mode and the speed of sound in the
long-wavelength limit are obtained by solving the Bethe-Salpeter equations for
the collective modes of the attractive Hubbard Hamiltonian.
\\ ( http://arxiv.org/abs/1006.1392 , 52kb)
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arXiv:1006.1438
Date: Tue, 8 Jun 2010 01:44:53 GMT (90kb,D)

Title: Semiclassical dynamics of quasi-one-dimensional, attractive
Bose-Einstein condensates
Authors: Alexander Tovbis and Mark A. Hoefer
Categories: cond-mat.quant-gas
\\
The strongly interacting regime for attractive Bose-Einstein condensates
(BECs) tightly confined in an extended cylindrical trap is studied. For
appropriately prepared BECs, the ensuing dynamics are found to be governed by
the one-dimensional focusing Nonlinear Schr\"{o}dinger equation (NLS) in the
semiclassical (small dispersion) regime. In spite of the modulational
instability of this regime, rigorous results on the strong asymptotics of the
semiclassical limiting solutions were obtained recently. Using these results,
"implosion" and "explosion" events are predicted whereby an initial hump
focuses into a sharp spike which then expands into rapid oscillations.
Seemingly related behavior has been observed in three-dimensional experiments
and models, where the supercritical NLS equation is known to admit a blow-up
singularity (collapse). The dynamical regimes studied here, however, are not
predicted to undergo collapse. Instead, distinct, ordered structures, appearing
after the "implosion", yield new observables that may be experimentally
accessible.
\\ ( http://arxiv.org/abs/1006.1438 , 90kb)
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arXiv:1006.1495
Date: Tue, 8 Jun 2010 09:22:19 GMT (64kb)

Title: Fast optimal transition between two equilibrium states
Authors: Jean-Fran\ccois Schaff, Xiao-Li Song, Patrizia Vignolo, and Guillaume
Labeyrie
Categories: cond-mat.quant-gas
\\
We present the first experimental demonstration of a technique based on
invariants of motion for a time-dependent Hamiltonian, allowing a fast
transition to a final equilibrium state identical to that obtain through a
perfectly adiabatic transformation. This method is applied to the fast
decompression of an ultracold cloud of $^{87}$Rb atoms held in a harmonic
magnetic trap, in the presence of gravity. Using an optimal frequency
trajectory, we are able to decompress the trap by a factor of 15 within 35 ms
with a strong suppression of the sloshing/breathing hybrid modes induced by the
large vertical displacement and curvature reduction of the trap. When compared
to a standard linear decompression, we achieve a gain of a factor 37 on the
transition time.
\\ ( http://arxiv.org/abs/1006.1495 , 64kb)
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arXiv:1006.1554
Date: Tue, 8 Jun 2010 13:32:34 GMT (595kb)

Title: Designing Zeeman slower for strontium atoms - towards optical atomic
clock
Authors: Marcin Bober, Jerzy Zachorowski, Wojciech Gawlik
Categories: physics.atom-ph
\\
We report on design and construction of a Zeeman slower for strontium atoms
which will be used in an optical atomic clock experiment. The paper describes
briefly required specifications of the device, possible solutions, and
concentrates on the chosen design. The magnetic field produced by the built
Zeeman slower has been measured and compared with the simulations. The system
consisting of an oven and Zeeman slower are designed to produce an atomic beam
of 10-12 s-1 flux and final velocity of ~30 m/s.
\\ ( http://arxiv.org/abs/1006.1554 , 595kb)
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arXiv:1006.1685
Date: Wed, 9 Jun 2010 02:25:54 GMT (35kb)

Title: Mott Transitions of Three-Component Fermionic Atoms with Repulsive
Interaction in Optical Lattices
Authors: Kensuke Inaba, Shin-ya Miyatake and Sei-ichiro Suga
Categories: cond-mat.quant-gas
\\
We investigate the Mott transitions of three-component (colors) repulsive
fermionic atoms in optical lattices using the dynamical mean field theory. We
find that for SU(3) symmetry breaking interactions the Mott transition occurs
at incommensurate half filling. As a result, a characteristic Mott insulating
state appears, where paired atoms with two different colors and atoms with the
third color are localized at different sites. We also find another Mott state
where atoms with two different colors are localized at different sites and
atoms with the third color remain itinerant. We demonstrate that these exotic
Mott phases can be detected by experimental double occupancy observations.
\\ ( http://arxiv.org/abs/1006.1685 , 35kb)
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arXiv:1006.1833 (*cross-listing*)
Date: Wed, 9 Jun 2010 15:28:09 GMT (1348kb)

Title: L\'evy-Schr\"odinger wave packets
Authors: Nicola Cufaro Petroni
Categories: math.PR cond-mat.stat-mech quant-ph
Report-no: Rapporto n. 11/2010 - Dpt. of Mathematics, Bari University
MSC-class: 60G51 Processes with independent increments, L\'evy processes 81P20
Stochastic mechanics
\\
We analyze the time-dependent solutions of the pseudo-differential
L\'evy-Schr\"odinger wave equation in the free (force-less) case, and we
compare them with the associated L\'evy processes. We first list the principal
laws used to describe the time evolutions of both L\'evy process densities and
L\'evy-Schr\"odinger wave packets. To have self-adjoint generators and unitary
evolutions we will consider only absolutely continuous, infinitely divisible
L\'evy noises with laws symmetric under change of sign of the independent
variable. We then show a few examples of the characteristic behavior of the
L\'evy-Schr\"odinger wave packets, and in particular of the bi-modality arising
in their evolutions: a feature at variance with the typical diffusive
uni-modality of the L\'evy process densities.
\\ ( http://arxiv.org/abs/1006.1833 , 1348kb)
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\\
arXiv:1006.1856 (*cross-listing*)
Date: Wed, 9 Jun 2010 16:55:31 GMT (52kb)

Title: A study of Quantum Correlations in Open Quantum Systems
Authors: Indranil Chakrabarty, Subhashish Banerjee, Nana Siddharth
Categories: quant-ph cond-mat.stat-mech
\\
In this work, we study quantum correlations in mixed states. The states
studied are modelled by a two-qubit system interacting with its environment via
a quantum nondemolition (purely dephasing) as well as dissipative type of
interaction. The entanglement dynamics of this two qubit system is analyzed and
the existence of entangled states which do not violate Bell's inequality, but
can still be useful as a potential resource for teleportation are reported. In
addition, a comparative study of various measures of quantum correlations, like
Concurrence, Bell's inequality, Discord and Teleportation fidelity, is made on
these states, generated by the above evolutions. Interestingly, examples are
found, of states, where entanglement is vanishing, but discord is
non-vanishing, bringing out the fact that entanglement is a subset of quantum
correlations.
\\ ( http://arxiv.org/abs/1006.1856 , 52kb)
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\\
arXiv:1006.1884
Date: Wed, 9 Jun 2010 19:31:20 GMT (1260kb,D)

Title: Vortices in quantum droplets: Analogies between boson and fermion
systems
Authors: H. Saarikoski, S.M. Reimann, A. Harju, M. Manninen
Categories: cond-mat.quant-gas cond-mat.mes-hall
Comments: Review article, 53 pages, 53 figures
\\
The main theme of this review is the many-body physics of vortices in quantum
droplets of bosons or fermions, in the limit of small particle numbers. Systems
of interest include cold atoms in traps as well as electrons confined in
quantum dots. When set to rotate, these in principle very different quantum
systems show remarkable analogies. The topics reviewed include the structure of
the finite rotating many-body state, universality of vortex formation and
localization of vortices in both bosonic and fermionic systems, and the
emergence of particle-vortex composites in the quantum Hall regime. An overview
of the computational many-body techniques sets focus on the configuration
interaction and density-functional methods. Studies of quantum droplets with
one or several particle components, where vortices as well as coreless vortices
may occur, are reviewed, and theoretical as well as experimental challenges are
discussed.
\\ ( http://arxiv.org/abs/1006.1884 , 1260kb)
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\\
arXiv:1006.1971
Date: Thu, 10 Jun 2010 07:58:42 GMT (273kb)

Title: Hybrid Quantum System of a Nanofiber Mode Coupled to Two Chains of
Optically Trapped Atoms
Authors: Hashem Zoubi, and Helmut Ritsch
Categories: quant-ph
\\
A tapered optical nanofiber simultaneously used to trap and optically
interface of cold atoms through evanescent fields constitutes a new and well
controllable hybrid quantum system. The atoms are trapped in two parallel 1D
optical lattices generated by suitable far blue and red detuned evanescent
field modes very close to opposite sides of the nanofiber surface. Collective
electronic excitations (excitons) of each of the optical lattices are
resonantly coupled to the second lattice forming symmetric and antisymmetric
common excitons. In contrast to the inverse cube dependence of the individual
atomic dipole-dipole interaction, we analytically find an exponentially
decaying coupling strength with distance between the lattices. The resulting
symmetric (bright) excitons strongly interact with the resonant nanofiber
photons to form fiber polaritons, which can be observed through linear optical
spectra. For large enough wave vectors the polariton decay rate to free space
is strongly reduced, which should render this system ideal for the realization
of long range quantum communication between atomic ensembles.
\\ ( http://arxiv.org/abs/1006.1971 , 273kb)
------------------------------------------------------------------------------
\\
arXiv:1006.1978 (*cross-listing*)
Date: Thu, 10 Jun 2010 08:39:26 GMT (35kb)

Title: Disordered quantum walk-induced localization of a Bose-Einstein
condensate
Authors: C. M. Chandrashekar
Categories: quant-ph cond-mat.quant-gas
\\
We present a new approach to Anderson localization in one-dimensional lattice
under the influence of disordered quantum coin operation in the quantum walk
evolution. We introduce a discrete-time quantum walk model in which
interference effect modified to diffuse or localize the probability
distribution by assigning different set of random coin parameter to each step
of the walk, respectively. Spatial localization of the particle/state is
explained by comparing the variance of the probability distribution of the
quantum walk in position space using disordered coin operation to that of the
walk using an identical coin operation for each step. Due to the high degree of
control over quantum coin operation and most of the system parameters,
ultracold atoms in optical lattice offer opportunities to implement disordered
quantum walk which is unitary and induce localization. Here we use a
Bose-Einstein condensate which can be evolved to the superposition of its
internal states in optical lattice to study Anderson localization. This
approach can be adopted to any other physical system in which controlled
disordered quantum walk can be implemented.
\\ ( http://arxiv.org/abs/1006.1978 , 35kb)
------------------------------------------------------------------------------
\\
arXiv:1006.2017
Date: Thu, 10 Jun 2010 12:35:25 GMT (44kb,D)

Title: Topological entanglement entropy relations for multi phase systems with
interfaces
Authors: F. A. Bais and J. K. Slingerland
Categories: cond-mat.str-el quant-ph
Comments: 4 pages, 3 figures, 2 tables, revtex
\\
We study the change in topological entanglement entropy that occurs when a
two-dimensional system in a topologically ordered phase undergoes a transition
to another such phase due to the formation of a Bose condensate. We also
consider the topological entanglement entropy of systems with domains in
different topological phases, and of phase boundaries between these domains. We
calculate the topological entropy of these interfaces and derive two
fundamental relations between the interface topological entropy and the bulk
topological entropies on both sides of the interface.
\\ ( http://arxiv.org/abs/1006.2017 , 44kb)
------------------------------------------------------------------------------
\\
arXiv:1006.2042
Date: Thu, 10 Jun 2010 14:17:43 GMT (196kb)

Title: Role of interactions in time-of-flight expansion of atomic clouds from
optical lattices
Authors: Joern N. Kupferschmidt (Cornell, Berlin), Erich J. Mueller (Cornell)
Categories: cond-mat.quant-gas
\\
We calculate the effect of interactions on the expansion of ultracold atoms
from a single site of an optical lattice. We use these results to predict how
interactions influence the interference pattern observed in a time of flight
experiment. We find that for typical interaction strengths their influence is
negligible, yet that they reduce visibility near a scattering resonance.
\\ ( http://arxiv.org/abs/1006.2042 , 196kb)
------------------------------------------------------------------------------
\\
arXiv:1006.2072
Date: Thu, 10 Jun 2010 16:03:58 GMT (66kb)

Title: Time-Reversal-Breaking and $d$-Wave Superfluidity of Ultracold Dipolar
Fermions in Optical Lattices
Authors: Li Han and C. A. R. S\'a de Melo
Categories: cond-mat.quant-gas
\\
We describe possible superfluid phases of ultracold dipolar fermions in
optical lattices for two-dimensional systems. Considering the many-body
screening of dipolar interactions at larger filling factors, we show that
several superfluid phases with distinct pairing symmetries naturally emerge in
the singlet channel: local $s$-wave $(sl)$, extended $s$-wave $(se)$, $d$-wave
$(d)$ or time-reversal-symmetry breaking $(sl + se \pm id)$-wave. The
temperature versus filling factor phase diagram indicates that $d$-wave is
favored near half-filling, that $(sl + se)$-wave is favored near zero or full
filling, and that time-reversal-breaking $(sl + se \pm id)$-wave is favored in
between. When a harmonic trap is included a sequence of phases can exist in the
cloud depending on the filling factor at the center of the trap. Most notably
in the region where the $(sl + se \pm id)$-wave superfluid exists, spontaneous
currents are generated, and may be detected using velocity sensitive Bragg
spectroscopy.
\\ ( http://arxiv.org/abs/1006.2072 , 66kb)
------------------------------------------------------------------------------
\\
arXiv:1006.2118
Date: Thu, 10 Jun 2010 19:08:38 GMT (115kb)

Title: Hidden Sp(2s+1)- or SO(2s+1)-symmetry and new exactly solvable models in
ultracold atomic systems
Authors: Yuzhu Jiang, Junpeng Cao and Yupeng Wang
Categories: cond-mat.str-el
\\
The high spin ultracold atom models with a special form of contact
interactions, i.e., the scattering lengthes in the total spin-$2,4 \cdots$
channels are equal but may be different from that in the spin-0 channel, is
studied. It is found that those models have either $Sp(2s+1)$-symmetry for the
fermions or $SO(2s+1)$-symmetry for the bosons in the spin sector. Based on the
symmetry analysis, a new class of exactly solvable models is proposed and
solved via the Bethe ansatz. The ground states for repulsive fermions are also
discussed.
\\ ( http://arxiv.org/abs/1006.2118 , 115kb)
------------------------------------------------------------------------------

The replacements:

------------------------------------------------------------------------------
\\
arXiv:0809.3532
replaced with revised version Mon, 7 Jun 2010 06:29:38 GMT (218kb)

Title: Spontaneous generation of a half-quantum vortex in spin-orbit coupled
Bose-Einstein condensates
Authors: Congjun Wu and Ian Mondragon-Shem
Categories: cond-mat.supr-con
\\ ( http://arxiv.org/abs/0809.3532 , 218kb)
------------------------------------------------------------------------------
\\
arXiv:0912.3667
replaced with revised version Mon, 7 Jun 2010 00:09:42 GMT (33kb)

Title: Comment on "Coherent Ratchets in Driven Bose-Einstein Condensates"
Authors: G. Benenti, G. Casati, S. Denisov, S. Flach, P. Hanggi, B. Li, and D.
Poletti
Categories: cond-mat.quant-gas
Journal-ref: Phys. Rev. Lett. 104, 228901 (2010)
DOI: 10.1103/PhysRevLett.104.228901
\\ ( http://arxiv.org/abs/0912.3667 , 33kb)
------------------------------------------------------------------------------
\\
arXiv:1002.0453
replaced with revised version Tue, 8 Jun 2010 12:52:33 GMT (1405kb)

Title: A finite element method with mesh adaptivity for computing vortex states
in fast-rotating Bose-Einstein condensates
Authors: Ionut Danaila (LJLL), Frederic Hecht (LJLL)
Categories: cond-mat.quant-gas math.NA physics.comp-ph
Comments: to appear in J. Computational Physics
\\ ( http://arxiv.org/abs/1002.0453 , 1405kb)
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\\
arXiv:1002.2311
replaced with revised version Fri, 4 Jun 2010 12:44:58 GMT (307kb)

Title: Imaging a single atom in a time-of-flight experiment
Authors: A. Fuhrmanek, A.M. Lance, C. Tuchendler, P. Grangier, Y.R.P. Sortais
and A. Browaeys
Categories: cond-mat.quant-gas physics.atom-ph
Journal-ref: New Journal of Physics 12, 053028 (2010)
\\ ( http://arxiv.org/abs/1002.2311 , 307kb)
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\\
arXiv:1002.3016
replaced with revised version Tue, 8 Jun 2010 13:57:09 GMT (3595kb)

Title: Photoemission spectrum and effect of inhomogeneous pairing fluctuations
in the BCS-BEC crossover regime of an ultracold Fermi gas
Authors: Shunji Tsuchiya, Ryota Watanabe, and Yoji Ohashi
Categories: cond-mat.quant-gas cond-mat.supr-con
Comments: 5 pages, 5 figures, Figures 4 and 5 are updated including
experimental data
\\ ( http://arxiv.org/abs/1002.3016 , 3595kb)
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\\
arXiv:1003.2634
replaced with revised version Thu, 10 Jun 2010 04:27:09 GMT (21kb)

Title: Antiferromagnetic Spinor Condensates are Quantum Rotors
Authors: Ryan Barnett, Jay D. Sau, and S. Das Sarma
Categories: cond-mat.quant-gas
Comments: minor revisions. some typos corrected
\\ ( http://arxiv.org/abs/1003.2634 , 21kb)
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\\
arXiv:1005.3577
replaced with revised version Wed, 9 Jun 2010 02:20:08 GMT (324kb)

Title: Time-of-flight imaging method to observe signatures of
antiferromagnetically ordered states of fermionic atoms in an optical lattice
Authors: Kensuke Inaba and Makoto Yamashita
Categories: cond-mat.quant-gas
\\ ( http://arxiv.org/abs/1005.3577 , 324kb)
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\\
arXiv:1006.1522 (*cross-listing*)
replaced with revised version Wed, 9 Jun 2010 13:25:49 GMT (0kb,I)

Title: Does Floquet theory always work?
Authors: Kushal Shah and Harishankar Ramachandran
Categories: physics.plasm-ph cond-mat.soft math-ph math.CA math.MP
Comments: This paper has been withdrawn by the authors. This paper is currently
under revision
\\ ( http://arxiv.org/abs/1006.1522 , 0kb)
------------------------------------------------------------------------------

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/
=========================================================================
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http://www.physics.uq.edu.au/people/mdavis/matts_arXiv/
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Received on Wed Sep 01 2010 - 11:01:37 EST

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