Dear subscribers,
This week we thank Mike Garrett. There are a massive 33 new preprints and 17
replacements:
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arXiv:0906.2202
Date: Fri, 12 Jun 2009 17:10:29 GMT (97kb)
Title: Pair Density Wave Instability of Cold Fermionic Atoms in an Optical
Lattice
Authors: Predrag Nikolic, A.A. Burkov, Arun Paramekanti
Categories: cond-mat.supr-con cond-mat.quant-gas
Comments: 4 pages, 3 figures
\\
We show that the band insulating state of cold fermionic atoms in a
three-dimensional cubic optical lattice is unstable to forming a pair-density
wave (PDW) state in the presence of strong attractive interactions induced by
proximity to a Feshbach resonance. The PDW state in this model is a special
type of supersolid, which arises from the condensation of predominantly
interband Cooper pairs at a nonzero, generically incommensurate, wavevector,
and is expected to be accompanied by an induced density modulation. We also
discuss the mean field phase diagram of a two-band tight binding model, which
exhibits a PDW state, and discuss the relation of the PDW instability in this
model to the Halperin-Rice exciton condensation instability in indirect bandgap
semiconductors.
\\ ( http://arxiv.org/abs/0906.2202 , 97kb)
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arXiv:0906.2264
Date: Fri, 12 Jun 2009 06:39:23 GMT (816kb)
Title: Entropy exchange in a mixture of ultracold atoms
Authors: J. Catani, G. Barontini, G. Lamporesi, F. Rabatti, G. Thalhammer, F.
Minardi, S. Stringari, M. Inguscio
Categories: cond-mat.quant-gas
Comments: 5 pages, 4 figures
\\
We investigate experimentally the entropy transfer between two
distinguishable atomic quantum gases at ultralow temperatures. Exploiting a
species-selective trapping potential, we are able to control the entropy of one
target gas in presence of a second auxiliary gas. With this method, we drive
the target gas into the degenerate regime in conditions of controlled
temperature by transferring entropy to the auxiliary gas. We envision that our
method could be useful both to achieve the low entropies required to realize
new quantum phases and to measure the temperature of atoms in deep optical
lattices.
\\ ( http://arxiv.org/abs/0906.2264 , 816kb)
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arXiv:0906.2314
Date: Fri, 12 Jun 2009 12:38:03 GMT (234kb)
Title: Decay of superfluid currents in the interacting one-dimensional Bose gas
Authors: Alexander Yu. Cherny, Jean-Sebastien Caux, and Joachim Brand
Categories: cond-mat.quant-gas cond-mat.stat-mech
Comments: 4 pages, 4 figures
\\
We examine the superfluid properties of a 1D Bose gas in a ring trap based on
the model of Lieb and Liniger. While the 1D Bose gas has nonclassical
rotational inertia and exhibits quantization of velocities, the metastability
of currents depends sensitively on the strength of interactions in the gas: the
stronger the interactions, the faster the current decays. It is shown that the
Landau critical velocity is zero in the thermodynamic limit due to the first
supercurrent state, which has zero energy and finite probability of excitation.
We calculate the energy dissipation rate of ring currents in the presence of
weak defects, which should be observable on experimental time scales.
\\ ( http://arxiv.org/abs/0906.2314 , 234kb)
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arXiv:0906.2033
Date: Thu, 11 Jun 2009 18:27:02 GMT (1341kb)
Title: Semiclassical Theory for Universality in Quantum Chaos with Symmetry
Crossover
Authors: Keiji Saito, Taro Nagao, Sebastian Muller, and Petr Braun
Categories: nlin.CD cond-mat.dis-nn
Comments: 24 pages, 4 figures
\\
We address the quantum-classical correspondence for chaotic systems with a
crossover between symmetry classes. We consider the energy level statistics of
a classically chaotic system in a weak magnetic field. The generating function
of spectral correlations is calculated by using the semiclassical
periodic-orbit theory. An explicit calculation up to the second order,
including the non-oscillatory and oscillatory terms, agrees with the prediction
of random matrix theory. Formal expressions of the higher order terms are also
presented. The nonlinear sigma (NLS) model of random matrix theory, in the
variant of the Bosonic replica trick, is also analyzed for the crossover
between the Gaussian orthogonal ensemble and Gaussian unitary ensemble. The
diagrammatic expansion of the NLS model is interpreted in terms of the periodic
orbit theory.
\\ ( http://arxiv.org/abs/0906.2033 , 1341kb)
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arXiv:0906.2257
Date: Fri, 12 Jun 2009 05:25:13 GMT (858kb)
Title: Generating a Fractal Butterfly Floquet Spectrum in a Class of Driven
SU(2) Systems
Authors: Jiao Wang and Jiangbin Gong
Categories: quant-ph
Comments: 11 pages, 9 figures, relatively large size, a full-length report of
the findings in arXiv 0906.2259
\\
A scheme for generating a fractal butterfly Floquet spectrum, first proposed
by Wang and Gong [Phys. Rev. A {\bf 77}, 031405(R) (2008)], is extended to
driven SU(2) systems such as a driven two-mode Bose-Einstein condensate. A new
class of driven systems without a link with the Harper model context is shown
to have an intriguing butterfly Floquet spectrum. The found butterfly spectrum
shows remarkable deviations from the known Hosftadter's butterfly. In addition,
the level crossings between Floquet states of the same parity and between
Floquet states of different parities are studied and highlighted. The results
are relevant to studies of fractal statistics, quantum chaos, coherent
destruction of tunneling, as well as the validity of mean-field descriptions of
Bose-Einstein condensates.
\\ ( http://arxiv.org/abs/0906.2257 , 858kb)
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arXiv:0906.2259
Date: Fri, 12 Jun 2009 05:23:25 GMT (410kb)
Title: Butterfly Floquet Spectrum in Driven SU(2) Systems
Authors: Jiao Wang and Jiangbin Gong
Categories: quant-ph
Comments: 4 pages, 4 figures, to appear in Phys. Rev. Lett., for a full-length
report see arXiv 0906.2257
\\
The Floquet spectrum of a class of driven SU(2) systems is shown to display a
butterfly pattern with multi-fractal properties. The level crossing between
Floquet states of the same parity or different parities is studied. The results
are relevant to studies of fractal statistics, quantum chaos, coherent
destruction of tunneling, and the validity of mean-field descriptions of
Bose-Einstein condensates.
\\ ( http://arxiv.org/abs/0906.2259 , 410kb)
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arXiv:0906.2272
Date: Fri, 12 Jun 2009 08:00:19 GMT (2069kb)
Title: Enhancement of thermal Casimir-Polder potentials of ground-state polar
molecules in a planar cavity
Authors: Simen A. Ellingsen, Stefan Yoshi Buhmann, Stefan Scheel
Categories: quant-ph
Comments: 12 pages, 10 figures
\\
We analyze the thermal Casimir-Polder potential experienced by a ground-state
molecule in a planar cavity and investigate the prospects for using such a
set-up for molecular guiding. The resonant atom-field interaction associated
with this non-equilibrium situation manifests itself in oscillating,
standing-wave components of the potential. While the respective potential wells
are normally too shallow to be useful, they may be amplified by a highly
reflecting cavity whose width equals a half-integer multiple of a particular
molecular transition frequency. We find that with an ideal choice of molecule
and the use of ultra-high reflectivity Bragg mirror cavity, it may be possible
to boost the potential by up to two orders of magnitude. We analytically derive
the scaling of the potential depth as a function of reflectivity and analyze
how it varies with temperature and molecular properties. It is also shown how
the potential depth decreases for standing waves with a larger number of nodes.
Finally, we investigate the lifetime of the molecular ground state in a thermal
environment and find that it is not greatly influenced by the cavity and
remains in the order of several seconds.
\\ ( http://arxiv.org/abs/0906.2272 , 2069kb)
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arXiv:0906.2458
Date: Sat, 13 Jun 2009 08:59:13 GMT (583kb)
Title: Generalized Entropy from Mixing: Thermodynamics, Mutual Information and
Symmetry Breaking
Authors: Fariel Shafee
Categories: cond-mat.stat-mech
Comments: This review paper was written in Jan 2009 after the author received
an invitation for a review paper based on three papers that are part of her
Princeton Uni PhD thesis. These are her personal papers and the thesis was
approved under the supervision of self by Princeton University (based on her
personal papers done while she was a degree candidate)
\\
We review a new form of entropy suggested by us, with origin in mixing of
states of systems due to interactions and deformations of phase cells. It is
demonstrated that this nonextensive form also leads to asymmetric maximal
entropy configurations unlike Shannon entropy. We discuss how, beginning with
quantum entanglement of microsystems with one another and with the environment,
one can obtain classical stochasticity for our form of entropy.
\\ ( http://arxiv.org/abs/0906.2458 , 583kb)
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arXiv:0906.2522
Date: Sun, 14 Jun 2009 08:54:06 GMT (30kb)
Title: Extension of the integrable, (1+1) Gross-Pitaevskii equation to chaotic
behaviour and arbitrary dimensions
Authors: Bernhard Mieck
Categories: cond-mat.stat-mech nlin.SI
\\
The integrable, (1+1) Gross-Pitaevskii (GP-) equation with hermitian property
is extended to chaotic behaviour as part of general complex fields within the
sl(2,C) algebra for Lax pairs. Furthermore, we prove the involution property of
conserved quantities in the case of GP-type equations with an arbitrary
external potential. We generalize the approach of Lax pair matrices to
arbitrary spacetime dimensions and conclude for the type of nonlinear equations
from the structure constants of the underlying algebra. One can also calculate
conserved quantities from loops within the (N-1) dimensional base space and the
mapping to the manifold of the general SL(n,C) group or a sub-group, provided
that the resulting fibre space is of nontrivial homotopic kind.
\\ ( http://arxiv.org/abs/0906.2522 , 30kb)
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arXiv:0906.2531
Date: Sun, 14 Jun 2009 12:08:42 GMT (39kb)
Title: Coherent state path integral and nonlinear sigma model for a condensate
composed of fermions with precise, discrete steps in the time development
Authors: Bernhard Mieck
Categories: cond-mat.stat-mech
\\
A coherent state path integral is considered for fermions with precise,
discrete time separation. We derive in detail a nonlinear sigma model of a pair
condensate concerning the precise, discrete time step order which is usually
abbreviated by the appealing (but in fact non-existent) hermitian form of the
fields. This problem is ubiquitous in quantum many-body physics and already
occurs in the original Dyson equation. However, one has only to include a few
amendments concerning the precise, discrete time step development of coherent
state path integrals, compared to previous, abridged approaches, so that one
can accomplish the exact treatment of a spontaneous symmetry breaking with a
coset decomposition for pair condensates and density parts.
\\ ( http://arxiv.org/abs/0906.2531 , 39kb)
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arXiv:0906.2532
Date: Sun, 14 Jun 2009 12:39:51 GMT (32kb)
Title: Field theory with coherent states for many-body problems with specified
particle- and symmetry- quantum numbers (Non-relativistic electrons in a
central potential and an external magnetic field)
Authors: Bernhard Mieck
Categories: cond-mat.stat-mech
\\
Coherent state path integrals are applied to a many-body problem for
non-relativistic electrons in a central potential and an external magnetic
field; however, in comparison to previous coherent state path integrals, we
definitely fix the symmetry quantum numbers to specific values with second
quantized field operators which are restricted by delta functions of a Dirac
identity in a trace representation of anti-commuting coherent states. We
perform an anomalous doubling for the delta functions of the two-particle parts
so that a Hubbard-Stratonovich transformation can be taken for corresponding
self-energies with a coset decomposition. The given field theory can be
extended to an ensemble average over the external magnetic field so that mean
eigenvalue densities and eigenvalue correlations can be obtained.
\\ ( http://arxiv.org/abs/0906.2532 , 32kb)
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arXiv:0906.2551
Date: Sun, 14 Jun 2009 15:56:43 GMT (47kb)
Title: Induced supersolidity in a normal and hardcore boson mixture
Authors: Tapan Mishra, Ramesh V. Pai, B. P. Das
Categories: cond-mat.quant-gas
\\
It is well known that the supersolid form of matter can arise in a single
species of cold bosonic atoms in an optical lattice due to long range
interactions. We present a scenario where a supersolid is induced in one of the
components of a mixture of two species bosonic atoms where there is no long
range interactions. We study a system of normal and hardcore boson mixture with
only the former possessing long range interactions. We consider three cases:
the first where the total density is commensurate and the other two where they
are incommensurate . By suitable choices of the densities and the interaction
strengths of the atoms, we predict that the charge density wave and the
supersolid orders can be induced in the hardcore species as a result of the
competing interatomic interactions.
\\ ( http://arxiv.org/abs/0906.2551 , 47kb)
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arXiv:0906.2567
Date: Sun, 14 Jun 2009 18:33:09 GMT (190kb,D)
Title: Adiabatic preparation of many-body states in optical lattices
Authors: Anders S. Sorensen, Ehud Altman, Michael Gullans, J. V. Porto, Mikhail
D. Lukin, and Eugene Demler
Categories: cond-mat.quant-gas
Comments: 4+epsilon pages
\\
We analyze a technique for the preparation of low entropy many body states of
atoms in optical lattices based on adiabatic passage. In particular, we show
that this method allows preparation of strongly correlated states as stable
highest energy states of Hamiltonians that have trivial ground states. As an
example, we analyze the generation of antiferromagnetically ordered states by
adiabatic change of a staggered field acting on the spins of bosonic atoms with
ferromagnetic interactions.
\\ ( http://arxiv.org/abs/0906.2567 , 190kb)
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arXiv:0906.2580
Date: Mon, 15 Jun 2009 00:16:22 GMT (63kb)
Title: Exotic superfluidity in cold atoms
Authors: Elena Gubankova
Categories: cond-mat.quant-gas
Comments: 12 pages, 6 figures, proceedings of the conference "Shifmania,
Crossing the Boundaries: Gauge Dynamics at Strong Coupling", May 14-17, 2009
\\
We derived the low energy effective action for the collective modes in
asymmetric fermionic systems with attractive interaction. We obtained the phase
diagram in terms of the chemical potentials. It features a stable gapless
superfluidity with one Fermi surface on the BEC side of the resonance. Also we
predict a sharp increase in outer core of a vortex, i.e. vortex size, upon
entering into the gapless phase. This may serve as a signature of a gapless
phase.
\\ ( http://arxiv.org/abs/0906.2580 , 63kb)
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arXiv:0906.2610
Date: Mon, 15 Jun 2009 05:12:43 GMT (435kb,D)
Title: Transition region properties of a trapped quasi-two-dimensional
degenerate Bose gas
Authors: R. N. Bisset and P. B. Blakie
Categories: cond-mat.quant-gas
Comments: 5 pages 5 figures
\\
The c-field simulation technique is used to study a trapped quasi-two
dimensional Bose gas. We calculate the central curvature of the system density
and fluctuations of the condensate mode in the degenerate regime. These results
provide new understanding of the system behavior in the region of the
superfluid transition.
\\ ( http://arxiv.org/abs/0906.2610 , 435kb)
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arXiv:0906.2624
Date: Mon, 15 Jun 2009 07:43:50 GMT (405kb)
Title: Cavity Quantum Optomechanics of Ultracold Atoms in an Optical Lattice:
Normal-Mode Splitting
Authors: Aranya B Bhattacherjee
Categories: cond-mat.quant-gas
Comments: 6 figures
\\
We consider the dynamics of a movable mirror (cantilever) of a cavity coupled
through radiation pressure to the light scattered from ultracold atoms in an
optical lattice. Scattering from different atomic quantum states creates
different quantum states of the scattered light, which can be distinguished by
measurements of the displacement spectrum of the cantilever. We show that for
large pump intensities the steady state displacement of the cantilever shows
bistable behaviour. Due to atomic back-action, the displacement spectrum of the
cantilever is modified and depends on the position of the condensate in the
Brillouin zone. We further analyze the occurrence of splitting of the normal
mode into three modes due to mixing of the mechanical motion with the
fluctuations of the cavity field and the fluctuations of the condensate with
finite atomic two-body interaction. The present system offers a novel scheme to
coherently control ultracold atoms as well as cantilever dynamics.
\\ ( http://arxiv.org/abs/0906.2624 , 405kb)
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arXiv:0906.2640
Date: Mon, 15 Jun 2009 09:13:23 GMT (37kb)
Title: Trap-size scaling in confined particle systems at quantum transitions
Authors: Massimo Campostrini, Ettore Vicari
Categories: cond-mat.stat-mech
Comments: 4 pages, 2 figures
\\
We develop a trap-size scaling theory for trapped particle systems at quantum
transitions. As a theoretical laboratory, we consider a quantum XY chain in an
external transverse field acting as a trap for the spinless fermions of its
quadratic Hamiltonian representation. We discuss the trap-size scaling at the
Mott insulator to superfluid transition in the boson Hubbard model. We present
exact and accurate numerical results for the XY chain and for the hard-core
limit of the one-dimensional boson Hubbard model. Our results are relevant for
systems of cold atomic gases in optical lattices.
\\ ( http://arxiv.org/abs/0906.2640 , 37kb)
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arXiv:0906.2757
Date: Mon, 15 Jun 2009 18:37:46 GMT (14kb)
Title: S-ordered phase-space path integrals and time-s-ordering of Heisenberg
operators (reseach notes)
Authors: L.I.Plimak
Categories: cond-mat.stat-mech
\\
Formal structure of phase-space path integrals based on different types of
operator orderings is analysed.
\\ ( http://arxiv.org/abs/0906.2757 , 14kb)
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arXiv:0906.2572
Date: Sun, 14 Jun 2009 22:20:17 GMT (614kb,P)
Title: Squeezing of Atomic Quantum Projection Noise
Authors: Patrick J. Windpassinger, Daniel Oblak, Ulrich B. Hoff, Anne Louchet,
Jurgen Appel, Niels Kjaergaard, and Eugene S. Polzik
Categories: quant-ph
Comments: Submitted to Journal of Modern Optics
\\
We provide a framework for understanding recent experiments on squeezing of a
collective atomic pseudo-spin, induced by a homodyne measurement on
off-resonant probe light interrogating the atoms. The detection of light
decimates the atomic state distribution and we discuss the conditions under
which the resulting reduced quantum fluctuations are metrologically relevant.
In particular, we consider a dual probe scheme which benefits from a
cancelation of classical common mode noise sources such that quantum
fluctuations from light and atoms are the main contributions to the detected
signal.
\\ ( http://arxiv.org/abs/0906.2572 , 614kb)
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arXiv:0906.2904
Date: Tue, 16 Jun 2009 12:12:14 GMT (1387kb)
Title: Laser Cooling by Collisional Redistribution of Radiation
Authors: Ulrich Vogl and Martin Weitz
Categories: cond-mat.quant-gas
Comments: Nature (in press)
\\
The general idea that optical radiation may cool matter was put forward by
Pringsheim already in 1929. Doppler cooling of dilute atomic gases is an
extremely successful application of this concept, and more recently anti-Stokes
cooling in multilevel systems has been explored, culminating in the optical
refrigeration of solids. Collisional redistribution of radiation is a proposed
different cooling mechanism that involves atomic two-level systems, though
experimental investigations in gases with moderate density have so far not
reached the cooling regime.
Here we experimentally demonstrate laser cooling of an atomic gas based on
collisional redistribution of radiation, using rubidium atoms subject to 230
bar of argon buffer gas pressure. The frequent collisions in the ultradense gas
transiently shift a far red detuned laser beam into resonance, while
spontaneous decay occurs close to the unperturbed atomic resonance frequency.
During each excitation cycle, a kinetic energy of order of the thermal energy
k_B T is extracted from the dense atomic sample. In a proof of principle
experiment with a thermally non-isolated sample, we experimentally demonstrate
relative cooling by 66 K. The cooled gas has a density of more than 10 orders
of magnitude above the typical values in Doppler cooling experiments, and the
cooling power reaches 87 mW. Future prospects of the demonstrated effect
include studies of supercooling beyond the homogeneous nucleation temperature
and optical chillers.
\\ ( http://arxiv.org/abs/0906.2904 , 1387kb)
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arXiv:0906.2908
Date: Tue, 16 Jun 2009 12:19:47 GMT (48kb)
Title: Anomalous behavior of q-averages in nonextensive statistical mechanics
Authors: Sumiyoshi Abe (1,2,3) ((1) Mie University, Mie, Japan, (2) ISMANS, Le
Mans, France, (3) Inspire Institute Inc., Virginia, USA)
Categories: cond-mat.stat-mech
Comments: 14 pages, no figures. Accepted for publication in J. Stat. Mech.
\\
A generalized definition of average, termed the q-average, is widely employed
in the field of nonextensive statistical mechanics. Recently, it has however
been pointed out that such an average value may behave unphysical under
specific deformations of probability distributions. Here, the following three
issues are discussed and clarified. Firstly, the deformations considered are
physical and may experimentally be realized. Secondly, in view of
thermostatistics, the q-average is unstable in both finite and infinite
discrete systems. Thirdly, a naive generalization of the discussion to
continuous systems misses a point, and a norm better than the $L^1$-norm should
be employed for measuring the distance between two probability distributions.
Consequently, stability of the q-average is shown not to be established in all
the cases.
\\ ( http://arxiv.org/abs/0906.2908 , 48kb)
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arXiv:0905.0669
Date: Tue, 5 May 2009 18:49:18 GMT (372kb)
Date (revised v2): Thu, 14 May 2009 19:43:40 GMT (421kb)
Title: Unitary circuits for strongly correlated fermions
Authors: C. Pineda, T. Barthel, J. Eisert
Categories: quant-ph cond-mat.str-el
Comments: 5 pages, 3 figures, numerical example added, small typographic errors
corrected
\\
We introduce a scheme for efficiently describing pure states of strongly
correlated fermions in higher dimensions using unitary circuits. A local way of
computing local expectation values is presented. We formulate a dynamical
reordering scheme, corresponding to time-adaptive Jordan-Wigner transformation
that avoids non-local string operators and only keeps suitably ordered the
causal cone. Primitives of such a reordering scheme are highlighted. Fermionic
unitary circuits can be contracted with the same complexity as in the spin
case. The scheme gives rise to a variational description of fermionic models
that does not suffer from a sign problem. We present a numerical example on a
9x9 fermionic lattice model to show the functioning of the approach.
\\ ( http://arxiv.org/abs/0905.0669 , 421kb)
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arXiv:0906.2842
Date: Tue, 16 Jun 2009 04:37:50 GMT (2045kb)
Title: Synchronization in non dissipative optical lattices
Authors: Daniel Hennequin (PhLAM), Philippe Verkerk (PhLAM)
Categories: physics.atom-ph
\\
The dynamics of cold atoms in conservative optical lattices obviously depends
on the geometry of the lattice. But very similar lattices may lead to deeply
different dynamics. For example, in a 2D optical lattice with a square mesh,
the sign of the detuning plays a crucial role: in the blue detuned case,
trajectories of an atom inside a well are chaotic for high enough energies. On
the contrary, in the red detuned case, chaos is completely inhibited inside the
wells. Here, we study in details the dynamical regimes of atoms inside a well
of a red detuned lattice, with the aim to understand the dynamical mechanisms
leading to the disappearance of chaos. We show that the motions in the two
directions of space are frequency locked in most of the phase space, for most
of the parameters of the lattice and atoms. This synchronization, not as strict
as that of a dissipative system, is nevertheless a mechanism powerful enough to
explain that chaos cannot appear in red detuned lattices.
\\ ( http://arxiv.org/abs/0906.2842 , 2045kb)
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arXiv:0906.2880
Date: Tue, 16 Jun 2009 09:32:29 GMT (1586kb)
Title: Thermal properties of AlN-based atom chips
Authors: Julien Armijo (LCFIO), Carlos Garrido Alzar (LCFIO), Isabelle
Bouchoule (LCFIO)
Categories: physics.atom-ph
\\
We have studied the thermal properties of atom chips consisting o high
thermal conductivity Aluminum Nitride (AlN) substrates on which gold microwires
are directly deposited. We have measured the heating of wires of several widths
and with different thermal couplings to the copper mount holding the chip. The
results are in good agreement with a theoretical model where the copper mount
is treated as a heat sink and the thermal interface resistance between the wire
and the substrate is vanishing. We give analytical formulas describing the
different transient heating regimes and the steady state. We identify criteria
to optimize the design of a chip as well as the maximal currents $I_c$ that can
be fed in the wires. For a 600$\mu$m thick-chip glued on a copper block with
Epotek H77, we find $I_c=16$A for a 3$\mu$m high, 200$\mu$m wide-wire.
\\ ( http://arxiv.org/abs/0906.2880 , 1586kb)
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arXiv:0906.2971
Date: Tue, 16 Jun 2009 16:54:03 GMT (1341kb,D)
Title: Laser-induced 3D alignment and orientation of quantum-state-selected
molecules
Authors: Iftach Nevo, Lotte Holmegaard, Jens H. Nielsen, Jonas L. Hansen,
Henrik Stapelfeldt, Frank Filsinger, Gerard Meijer, Jochen K\"upper
Categories: physics.chem-ph physics.atm-clus physics.atom-ph
Comments: 8 pages, 7 figures
\\
A strong inhomogeneous static electric field is used to spatially disperse a
rotationally cold supersonic beam of 2,6-difluoroiodobenzene molecules
according to their rotational quantum state. The molecules in the lowest lying
rotational states are selected and used as targets for 3-dimensional alignment
and orientation. The alignment is induced in the adiabatic regime with an
elliptically polarized, intense laser pulse and the orientation is induced by
the combined action of the laser pulse and a weak static electric field. We
show that the degree of 3-dimensional alignment and orientation is strongly
enhanced when rotationally state-selected molecules, rather than molecules in
the original molecular beam, are used as targets.
\\ ( http://arxiv.org/abs/0906.2971 , 1341kb)
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arXiv:0906.3042
Date: Tue, 16 Jun 2009 23:05:35 GMT (449kb)
Title: Optical Kagome lattice for ultra-cold atoms with nearest neighbor
interactions
Authors: J. Ruostekoski
Categories: cond-mat.quant-gas cond-mat.str-el
\\
We propose a scheme to implement an optical Kagome lattice for ultra-cold
atoms with controllable s-wave interactions between nearest neighbor sites and
a gauge potential. The atoms occupy three different internal atomic levels with
electromagnetically-induced coupling between the levels. We show that by
appropriately shifting the triangular lattice potentials, experienced by atoms
in different levels, the Kagome lattice can be realized using only two standing
waves, generating a highly frustrated quantum system for the atoms.
\\ ( http://arxiv.org/abs/0906.3042 , 449kb)
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arXiv:0906.3081
Date: Wed, 17 Jun 2009 07:03:58 GMT (67kb)
Title: Berry Phase in Atom-Molecule Conversion Systems and Fractional Monopole
Authors: Li-Bin Fu and Jie Liu
Categories: cond-mat.quant-gas
Comments: 4 pages, 1 figure
\\
We investigate the geometric phase or Berry phase of adiabatic quantum
evolution in an atom-molecule conversion system, and find that the Berry phase
in such system consists of two parts: the usual Berry connection term and a
novel term from the nonlinearity brought forth by the atom-molecule conversion.
The geometric phase can be viewed as the flux of the magnetic field of a
monopole through the surface enclosed by a closed path in parameter space. The
charge of the monopole, however, is found to be one third of the elementary
charge of the usual quantized monopole.
\\ ( http://arxiv.org/abs/0906.3081 , 67kb)
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arXiv:0906.3142
Date: Wed, 17 Jun 2009 14:38:21 GMT (493kb)
Title: Numerical Studies of Counterflow Turbulence, Velocity Distribution of
Vortices
Authors: Hiroyuki Adachi and Makoto Tsubota
Categories: cond-mat.other
Comments: 6 pages, 12 figures, svjour3.sty
\\
We performed the numerical simulation of quantum turbulence produced by
thermal counterflow in superfluid $^{4}${\rm He} by using the vortex filament
model. The pioneering work was made by Schwarz, which has two defects. One is
neglecting non-local terms of the Biot-Savart integral (localized induction
approximation, LIA), and the other is the unphysical mixing procedure in order
to sustain the statistically steady state of turbulence. We succeeded in making
the statistically steady state without the LIA and the mixing. This state shows
the characteristic relation $L=\gamma^2 v_{ns}^2$ between the
line-length-density $L$ and the counterflow relative velocity $v_{ns}$ with the
quantitative agreement of the coefficient $\gamma$ with some typical
observations. We compare our numerical results to the observation of experiment
by Paoletti {\it et al}, where thermal couterflow was visualized by solid
hydrogen particles.
\\ ( http://arxiv.org/abs/0906.3142 , 493kb)
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arXiv:0906.3190
Date: Wed, 17 Jun 2009 14:24:10 GMT (113kb)
Title: Tunable ultranarrow linewidth of cavity induced by interacting dark
resonances
Authors: Y. D. Peng, L. L. Jin, Y. P. Niu, and S. Q. Gong
Categories: quant-ph
Comments: 4 pages, 5 figures
\\
A scheme for getting a tunable ultranarrow linewidth of a cavity due to an
embedded four-level atomic medium with double-dark resonances is proposed. It
is shown that the steep dispersion induced by double-dark resonances in the
transparency window leads to the ultranarrow transmission peak. Compared with
the case of a single-dark-resonance system, the linewidth can be narrowed even
by one order under proper conditions. Furthermore, the position of the
ultranarrow peak can be engineered by varying the intensity and detuning of the
control field.
\\ ( http://arxiv.org/abs/0906.3190 , 113kb)
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\\
arXiv:0906.3196
Date: Wed, 17 Jun 2009 14:32:53 GMT (11kb)
Title: Correlations in Free Fermionic States
Authors: M. Fannes and J. Wouters
Categories: quant-ph
Comments: 17 pages, no figures
\\
We study correlations in a bipartite, Fermionic, free state in terms of
perturbations induced by one party on the other. In particular, we show that
all so conditioned free states can be modelled by an auxiliary Fermionic system
and a suitable completely positive map.
\\ ( http://arxiv.org/abs/0906.3196 , 11kb)
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\\
arXiv:0906.3206
Date: Wed, 17 Jun 2009 15:33:03 GMT (294kb)
Title: Tackling the Gross-Pitaevskii energy functional with the Sobolev
gradient - Analytical and numerical results
Authors: P. Kazemi, M. Eckart
Categories: quant-ph
Comments: 30 pages, 9 figures, 3 tables
\\
In the first part of this contribution we prove the global existence and
uniqueness of a trajectory that globally converges to the minimizer of the
Gross-Pitaevskii energy functional for a large class of external potentials.
Using the method of Sobolev gradients we can provide an explicit construction
of this minimizing sequence.
In the second part we numerically apply these results to a specific
realization of the external potential and illustrate the main benefits of the
method of Sobolev gradients, which are high numerical stability and rapid
convergence towards the minimizer.
\\ ( http://arxiv.org/abs/0906.3206 , 294kb)
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\\
arXiv:0906.3316
Date: Wed, 17 Jun 2009 21:45:56 GMT (913kb)
Title: Phase Separation and Dynamics of Two-component Bose-Einstein Condensates
Authors: R. Navarro, R. Carretero-Gonzalez, and P.G. Kevrekidis
Categories: cond-mat.quant-gas
Comments: 16 pages, 22 figures, submitted to Phys. Rev. A
\\
We study the interactions between two atomic species in a binary
Bose-Einstein condensate to revisit the conditions for miscibility, oscillatory
dynamics between the species, steady state solutions and their stability. By
employing a variational approach for a quasi one-dimensional, two-atomic
species, condensate we obtain equations of motion for the parameters of each
species: amplitude, width, position and phase. A further simplification leads
to a reduction of the dynamics into a simple classical Newtonian system where
components oscillate in an effective potential with a frequency that depends on
the harmonic trap strength and the interspecies coupling parameter. We develop
explicit conditions for miscibility that can be interpreted as a phase diagram
that depends on the harmonic trap's strength and the interspecies species
coupling parameter. We numerically illustrate the bifurcation scenario whereby
non-topological, phase-separated states of increasing complexity emerge out of
a symmetric state, as the interspecies coupling is increased. The
symmetry-breaking dynamical evolution of some of these states is numerically
monitored and the associated asymmetric states are also explored.
\\ ( http://arxiv.org/abs/0906.3316 , 913kb)
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\\
arXiv:0906.3446
Date: Thu, 18 Jun 2009 14:09:23 GMT (76kb)
Title: Approximate expression for the dynamic structure factor in the
Lieb-Liniger model
Authors: Alexander Yu. Cherny and Joachim Brand
Categories: cond-mat.stat-mech cond-mat.quant-gas
Comments: 4 pages, 3 figures
Journal-ref: J. of Phys.: Conf. Ser. 129, 012051 (2008)
DOI: 10.1088/1742-6596/129/1/012051
\\
Recently, Imambekov and Glazman [Phys. Rev. Lett. 100, 206805 (2008)] showed
that the dynamic structure factor (DSF) of the 1D Bose gas demonstrates
power-law behaviour along the limiting dispersion curve of the collective modes
and calculated the corresponding exponents exactly. Combining these recent
results with a previously obtained strong-coupling expansion we present an
interpolation formula for the DSF of the 1D Bose gas. The obtained expression
is further consistent with exact low energy exponents from Luttinger liquid
theory and shows nice agreement with recent numerical results.
\\ ( http://arxiv.org/abs/0906.3446 , 76kb)
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The replacements:
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\\
arXiv:0903.1326
replaced with revised version Fri, 12 Jun 2009 18:10:50 GMT (353kb)
Title: Possible vortex fluid to supersolid transition in solid $^4$He below
about 75 mK
Authors: Nobutaka Shimizu, Yoshinori Yasuta, and Minoru Kubota
Categories: cond-mat.other
Comments: 4 pages, 5 figures
\\ ( http://arxiv.org/abs/0903.1326 , 353kb)
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\\
arXiv:0905.3634
replaced with revised version Thu, 11 Jun 2009 22:11:33 GMT (374kb)
Title: Black-hole radiation in Bose-Einstein condensates
Authors: Jean Macher and Renaud Parentani
Categories: cond-mat.quant-gas gr-qc
Comments: revTeX 4, 55 pages single-column, 19 figures; v2: figure and refs
added, typos corrected, some convention changes
\\ ( http://arxiv.org/abs/0905.3634 , 374kb)
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\\
arXiv:0802.0728
replaced with revised version Mon, 15 Jun 2009 11:28:35 GMT (166kb)
Title: Anomalous enhancement of quasiparticle current near a potential barrier
in a Bose-Einstein condensate
Authors: S. Tsuchiya, Y. Ohashi
Categories: cond-mat.other cond-mat.supr-con
Comments: 4 pages, 3 figures, published version
Journal-ref: Phys. Rev. A 78, 013628 (2008)
DOI: 10.1103/PhysRevA.78.013628
\\ ( http://arxiv.org/abs/0802.0728 , 166kb)
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\\
arXiv:0902.2908
replaced with revised version Mon, 15 Jun 2009 11:43:45 GMT (77kb)
Title: Supercurrent induced by tunneling Bogoliubov excitations in a
Bose-Einstein condensate
Authors: Shunji Tsuchiya, Yoji Ohashi
Categories: cond-mat.supr-con cond-mat.other
Comments: 36 pages, 12 figures, revised version as accepted by Phys. Rev. A
\\ ( http://arxiv.org/abs/0902.2908 , 77kb)
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\\
arXiv:cond-mat/9204009
replaced with revised version Tue, 16 Jun 2009 01:00:12 GMT (328kb)
Title: Order Parameters, Broken Symmetry, and Topology
Authors: James P. Sethna
Categories: cond-mat
Comments: Lectures Given at the Santa Fe Complexity Institute Summer School,
1991. Jeffrey Goldstone's name corrected
Journal-ref: 1991 Lectures in Complex Systems, eds. L. Nadel and D. Stein, SFI
Studies in the Sciences of Complexity, Proc. Vol. XV, Addison Wesley, 1992,
p. 243
\\ ( http://arxiv.org/abs/cond-mat/9204009 , 328kb)
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\\
arXiv:0901.4769
replaced with revised version Tue, 16 Jun 2009 19:35:11 GMT (160kb)
Title: Induced interactions for ultracold Fermi gases in optical lattices
Authors: D.-H. Kim, P. T\"orm\"a, J.-P. Martikainen
Categories: cond-mat.supr-con cond-mat.other
Comments: 4 pages, 4 figures
Journal-ref: Phys. Rev. Lett. 102, 245301 (2009)
DOI: 10.1103/PhysRevLett.102.245301
\\ ( http://arxiv.org/abs/0901.4769 , 160kb)
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\\
arXiv:0812.1387
replaced with revised version Tue, 16 Jun 2009 12:01:55 GMT (565kb)
Title: Effective three-body interactions of neutral bosons in optical lattices
Authors: P.R. Johnson, E. Tiesinga, J.V. Porto, C.J. Williams
Categories: quant-ph
Comments: Expanded version; some issues in the perturbation theory are
corrected and clarified
\\ ( http://arxiv.org/abs/0812.1387 , 565kb)
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\\
arXiv:0902.3964
replaced with revised version Tue, 16 Jun 2009 16:13:28 GMT (927kb,D)
Title: Single photon nonlinearities using arrays of cold polar molecules
Authors: R.M. Rajapakse, T. Bragdon, A.M. Rey, T. Calarco, S. F. Yelin
Categories: quant-ph
Comments: 8 pages, 9 figures Accepted for publication in Physical Review A
\\ ( http://arxiv.org/abs/0902.3964 , 927kb)
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\\
arXiv:0904.4210
replaced with revised version Tue, 16 Jun 2009 15:15:02 GMT (335kb)
Title: Quantum optics with quantum gases: controlled state reduction by
designed light scattering
Authors: Igor B. Mekhov, Helmut Ritsch
Categories: quant-ph cond-mat.other physics.atom-ph physics.optics
Comments: updated, to be published in Phys. Rev. A
\\ ( http://arxiv.org/abs/0904.4210 , 335kb)
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\\
arXiv:0904.1552
replaced with revised version Wed, 17 Jun 2009 15:13:54 GMT (464kb)
Title: Pair-supersolid phase in a bilayer system of dipolar lattice bosons
Authors: C. Trefzger, C. Menotti, and M. Lewenstein
Categories: cond-mat.other
Comments: 4 pages, 3 figures
\\ ( http://arxiv.org/abs/0904.1552 , 464kb)
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\\
arXiv:0905.4948
replaced with revised version Wed, 17 Jun 2009 18:04:40 GMT (71kb,D)
Title: Ultracold Gases of Ytterbium: Ferromagnetism and Mott States in an SU(6)
Fermi System
Authors: M. A. Cazalilla, A. F. Ho, and M. Ueda
Categories: cond-mat.quant-gas cond-mat.str-el
Comments: 4+ pages, 1 figure; v2: Improved discussion of the SU(6)
symmetry-breaking patterns
\\ ( http://arxiv.org/abs/0905.4948 , 71kb)
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\\
arXiv:0903.2050
replaced with revised version Tue, 16 Jun 2009 22:03:38 GMT (215kb,D)
Title: Magnetometry via a double-pass continuous quantum measurement of atomic
spin
Authors: Bradley A. Chase, Ben Q. Baragiola, Heather L. Partner, Brigette D.
Black, JM Geremia
Categories: quant-ph
Comments: 17 pages, updated to match print version
Journal-ref: Phys. Rev. A, 79, 062107 (2009)
DOI: 10.1103/PhysRevA.79.062107
\\ ( http://arxiv.org/abs/0903.2050 , 215kb)
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\\
arXiv:0903.1485
replaced with revised version Wed, 17 Jun 2009 09:22:35 GMT (16kb)
Title: Manipulating Higher Partial-Wave Atom-Atom Interaction by Strong
Photoassoiative Coupling
Authors: Bimalendu Deb and Jisha Hazra
Categories: physics.atom-ph physics.optics
Comments: Accepted for publication in Physical Review Letters; 4 pages 1 figure
\\ ( http://arxiv.org/abs/0903.1485 , 16kb)
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\\
arXiv:0808.2565
replaced with revised version Thu, 18 Jun 2009 12:06:16 GMT (132kb)
Title: Localized states and interaction induced delocalization in Bose gases
with quenched disorder
Authors: G.M. Falco, T. Nattermann and V.L. Pokrovsky
Categories: cond-mat.other cond-mat.stat-mech
Comments: 17 pages, 5 figure
Journal-ref: Europhysics Letters {\bf 85}, 30002 (2009)
DOI: 10.1209/0295-5075/85/30002
\\ ( http://arxiv.org/abs/0808.2565 , 132kb)
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\\
arXiv:0809.1056
replaced with revised version Thu, 18 Jun 2009 15:14:10 GMT (190kb)
Title: Groundstatable fermionic wavefunctions and their associated many-body
Hamiltonians
Authors: D. Charrier and C. Chamon
Categories: cond-mat.str-el
Comments: 12 pages, 16 figures, extensively revised
\\ ( http://arxiv.org/abs/0809.1056 , 190kb)
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\\
arXiv:0904.1569
replaced with revised version Wed, 17 Jun 2009 20:54:01 GMT (7084kb)
Title: Induced interaction and crystallization of self-localized impurity
fields in a Bose-Einstein condensate
Authors: Sergio Rica and David C. Roberts
Categories: cond-mat.quant-gas
Comments: v2: movies will be linked from Phys Rev A website; corrected
hysteresis discussion; other minor edits; 16 pages, 9 figures, (32 fig. files
including subfigures)
\\ ( http://arxiv.org/abs/0904.1569 , 7084kb)
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\\
arXiv:0904.2399
replaced with revised version Wed, 17 Jun 2009 20:18:50 GMT (137kb)
Title: Bose-Einstein and Fermi-Dirac distributions in nonextensive quantum
statistics: An exact approach
Authors: Hideo Hasegawa (Tokyo Gakugei Univ.)
Categories: cond-mat.stat-mech cond-mat.other
Comments: 34 pages, 11 figures; augmented the text
\\ ( http://arxiv.org/abs/0904.2399 , 137kb)
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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 Mon Jul 13 2009 - 11:09:56 EST
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