# Matt's arXiv selection: week ending Friday 13th July 2007

From: Matthew Davis <mdavis_at_physics.uq.edu.au>
Date: Wed, 25 Jul 2007 17:55:23 +1000 (EST)

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

Hi all,

There are 27 new preprint and 11 replacements for this week

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arXiv:0707.0870
Date: Thu, 5 Jul 2007 20:12:10 GMT (867kb)

Title: Two-Dimensional Dynamics of Ultracold Atoms in Optical Lattices
Authors: Michiel Snoek and Walter Hofstetter
Categories: cond-mat.other
Comments: 4 pages, 6 figures
\\
We analyze the dynamics of ultracold atoms in optical lattices induced by a
sudden shift of the underlying harmonic trapping potential. In order to study
the effect of strong interactions, dimensionality and lattice topology on
transport properties, we consider bosonic atoms with arbitrarily strong
repulsive interactions, on a two-dimensional square lattice and a hexagonal
lattice. On the square lattice we find insulating behavior for weakly
interacting atoms and slow relaxation for strong interactions, even when a Mott
plateau is present, which in one dimension blocks the dynamics. On the
hexagonal lattice the center of mass relaxes to the new equilibrium for any
interaction strength.
\\ ( http://arxiv.org/abs/0707.0870 , 867kb)
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arXiv:0707.0956
Date: Fri, 6 Jul 2007 12:23:45 GMT (83kb,D)

Title: Real-time path integral approach to nonequilibrium many-body quantum
system
Authors: Lothar M\"uhlbacher and Eran Rabani
Categories: cond-mat.mes-hall cond-mat.stat-mech
Comments: 5 pages, 2 figures
\\
A real-time path integral Monte Carlo approach is developed to study the
dynamics in a many-body quantum system until reaching a nonequilibrium
stationary state. The approach is based on augmenting an exact reduced equation
for the evolution of the system in the interaction picture which is amenable to
an efficient path integral (worldline) Monte Carlo approach. Results obtained
for a model of inelastic tunneling spectroscopy reveal the applicability of the
approach to a wide range of physically important regimes, including high
(classical) and low (quantum) temperatures, and weak (perturbative) and strong
electron-phonon couplings.
\\ ( http://arxiv.org/abs/0707.0956 , 83kb)
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arXiv:0707.0985
Date: Fri, 6 Jul 2007 14:53:40 GMT (22kb)

Title: Rotating molecules in optical lattices, alignment and monopole crystals
Authors: J.R. Holt and J.M.F. Gunn
Categories: cond-mat.other
Comments: 4 pages, 1 figure
\\
The recent progress towards production of near-ground state
quantum-degenerate molecules raises the issue of how such "small" molecules
behave in an optical lattice. In this Letter we show that the coupling of the
molecular orientation to the local electric field direction will provide
severalnew phenomena. In the case where the lasers forming different
crystallographic directions of the lattice are incoherent, the orientation of
the molecules is conserved (for L = 1) and a novel form of anisotropic
superfluidity can be expected. When the lasers are coherent, and the optical
lattice is such that the splitting of the rotational levels is large compared
to the centre of mass energies,an adiabaic description of the molecular
orientation is appropriate. This leads to geometric vector potentials,
pseudo-magnetic monopoles and a frustrated band structure with degenerate
minima.
\\ ( http://arxiv.org/abs/0707.0985 , 22kb)
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arXiv:0707.1016
Date: Fri, 6 Jul 2007 16:55:13 GMT (152kb)

Title: Spatial and spectral shape of inhomogeneous non-equilibrium
exciton-polariton condensates
Authors: M. Wouters, I. Carusotto, C. Ciuti
Categories: cond-mat.other
Comments: 5 pages, 3 figures
\\
We develop a mean-field theory of the spatial profile and the spectral
properties of polariton condensates in nonresonantly pumped semiconductor
microcavities in the strong coupling regime. Predictions are obtained for both
the continuous-wave and the pulsed excitation regimes and the specific
signatures of the non-equilibrium character of the condensation process are
pointed out. A striking sensitivity of the condensate shape on the optical pump
spot size is demonstrated by analytical and numerical calculations, in good
quantitative agreement with recent experimental observations.
\\ ( http://arxiv.org/abs/0707.1016 , 152kb)
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arXiv:math-ph/0601016 (*cross-listing*)
Date: Mon, 9 Jan 2006 01:59:04 GMT (179kb)

Title: Ground state properties of one-dimensional Bose-Fermi mixtures
Authors: Zi-Xiang Hu, Qiu-Lan Zhang and You-Quan Li
Categories: math-ph cond-mat.stat-mech cond-mat.str-el math.MP
Journal-ref: J. Phys. A: Math. Gen. 39, 351 (2006)
\\
Bose-Fermi mixtures in one dimension are studied in detail on the basis of an
exact solution. Corresponding to three possible choices of the referecce state
in the quantum inverse scattering method, three sets of Bethe-ansatz equations
are derived explicitly. The features of the ground state and low-lying
excitations are investigated. The ground state phase diagram caused by the
external field and chemical potential is obtained.
\\ ( http://arxiv.org/abs/math-ph/0601016 , 179kb)
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arXiv:0707.0902
Date: Fri, 6 Jul 2007 04:58:18 GMT (7kb)

Title: Flow Representation of the Bose-Hubbard Hamiltonian : General Case
Authors: Kazuyuki Fujii (Yokohama City University) and Tatsuo Suzuki (Shibaura
Institute of Technology)
Categories: quant-ph
Comments: Latex ; 8 pages ; 1 figure
\\
In this paper the explicit flow representation to the Bose-Hubbard
Hamiltonian is given in the general case. This representation may be useful in
creating cat states for the system of atoms trapped in the optical ring.
\\ ( http://arxiv.org/abs/0707.0902 , 7kb)
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arXiv:0707.0981
Date: Fri, 6 Jul 2007 14:38:20 GMT (884kb)

Title: Boson Pairs in a One-dimensional Split Trap
Authors: D.S. Murphy, J.F. McCann, J. Goold, Th. Busch
Categories: quant-ph
Comments: 9 pages, 8 figures
\\
We describe the properties of a pair of ultracold bosonic atoms in a
one-dimensional harmonic trapping potential with a tunable zero-ranged barrier
at the trap centre. The full characterisation of the ground state is done by
calculating the reduced single-particle density, the momentum distribution and
the two-particle entanglement. We derive several analytical expressions in the
limit of infinite repulsion (Tonks-Girardeau limit) and extend the treatment to
finite interparticle interactions by numerical solution. As pair interactions
in double wells form a fundamental building block for many-body systems in
periodic potentials, our results have implications for a wide range of
problems.
\\ ( http://arxiv.org/abs/0707.0981 , 884kb)
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arXiv:0707.1006
Date: Fri, 6 Jul 2007 16:08:56 GMT (147kb,D)

Title: The manifestation of quantum resonances and antiresonances in a finite
temperature dilute atomic gas
Authors: M. Saunders, P. L. Halkyard, K. J. Challis, S. A. Gardiner
Categories: physics.atom-ph
Comments: 15 pages, 7 figures
\\
We investigate the effect of temperature on resonant and antiresonant
dynamics in a dilute atomic gas kicked periodically by a standing wave laser
field. Our numerical calculations are based on a Monte Carlo method for an
incoherent mixture of non-interacting plane waves, and show that the atomic
dynamics are highly sensitive to the initial momentum width of the gas. We
explain this sensitivity by examining the time evolution of individual atomic
centre of mass momentum eigenstates with varying quasimomentum, and we have
determined analytic expressions for the evolution of the second-order momentum
moment to illustrate the range of behaviours.
\\ ( http://arxiv.org/abs/0707.1006 , 147kb)
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arXiv:0707.1205
Date: Mon, 9 Jul 2007 19:43:59 GMT (388kb)

Title: Non-Equilibrium Dynamics and Superfluid Ring Excitations in Binary
Bose-Einstein Condensates
Authors: K.M. Mertes, J. Merrill, R. Carretero-Gonzalez, D.J. Frantzeskakis,
P.G. Kevrekidis, and D.S. Hall
Categories: cond-mat.other
Comments: 4 pages, 3 figures (low res.), submitted to PRL
\\
We revisit a classic study [D. S. Hall {\it et al.}, Phys. Rev. Lett. {\bf
81}, 1539 (1998)] of interpenetrating Bose-Einstein condensates in the
hyperfine states $\ket{F = 1, m_f = -1}\equiv\ket{1}$ and $\ket{F = 2, m_f = +1}\equiv\ket{2}$ of ${}^{87}$Rb and observe striking new non-equilibrium
component separation dynamics in the form of oscillating ring-like structures.
The process of component separation is not significantly damped, a finding that
also contrasts sharply with earlier experimental work, allowing a clean first
look at a collective excitation of a binary superfluid. We further demonstrate
extraordinary quantitative agreement between theoretical and experimental
results using a multi-component mean-field model with key additional features:
the inclusion of atomic losses and the careful characterization of trap
potentials (at the level of a fraction of a percent).
\\ ( http://arxiv.org/abs/0707.1205 , 388kb)
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arXiv:0707.1233
Date: Mon, 9 Jul 2007 12:05:44 GMT (691kb)

Title: Condensate and superfluid fractions for varying interactions and
temperature
Authors: V.I. Yukalov and E.P. Yukalova
Categories: cond-mat.stat-mech
Comments: Latex file, 22 pages, 5 figures
Journal-ref: Phys. Rev. A 76 (2007) 013602-9
\\
A system with Bose-Einstein condensate is considered in the frame of the
self-consistent mean-field approximation, which is conserving, gapless, and
applicable for arbitrary interaction strengths and temperatures. The main
attention is paid to the thorough analysis of the condensate and superfluid
fractions in a wide region of interaction strengths and for all temperatures
between zero and the critical point T_c. The normal and anomalous averages are
shown to be of the same order for almost all interactions and temperatures,
except the close vicinity of T_c. But even in the vicinity of the critical
temperature, the anomalous average cannot be neglected, since only in the
presence of the latter the phase transition at T_c becomes of second order, as
it should be. Increasing temperature influences the condensate and superfluid
fractions in a similar way, by diminishing them. But their behavior with
respect to the interaction strength is very different. For all temperatures,
the superfluid fraction is larger than the condensate fraction. These coincide
only at T_c or under zero interactions. For asymptotically strong interactions,
the condensate is almost completely depleted, even at low temperatures, while
the superfluid fraction can be close to one.
\\ ( http://arxiv.org/abs/0707.1233 , 691kb)
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arXiv:0707.1302
Date: Mon, 9 Jul 2007 16:52:41 GMT (361kb)

Title: Possibility of supersolid with repulsive fermions in an anisotropic
optical lattice near a Feshbach resonance
Authors: B. Wang and L.-M. Duan
Categories: cond-mat.other cond-mat.str-el
Comments: 4 pages with 3 figures
\\
We present numerical analysis of ground state properties of the
one-dimensional general Hubbard model (GHM) with particle assisted tunnelling
rates and repulsive interaction, which describes fermionic atoms in an
anisotropic optical lattice near a wide Feshbach resonance. Our calculation
uses the time evolving block decimation algorithm, which is an extension of the
density matrix renormalization group and provides a well controlled method for
one-dimensional systems. We show the repulsive GHM, when hole doped from
half-filling, shows up a phase with coexistence of quasi-long-range superfluid
and charge-density-wave orders, suggesting the possibility of a supersolid.
This feature is different from the property of the conventional Hubbard model,
indicting the particle assisted tunnelling in the GHM could bring in
qualitatively new physics.
\\ ( http://arxiv.org/abs/0707.1302 , 361kb)
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arXiv:0707.1319
Date: Mon, 9 Jul 2007 18:44:11 GMT (33kb)

Title: Quantum Monte Carlo simulations of bosonic and fermionic impurities in a
two-dimensional hard-core boson system
Authors: Anders. W. Sandvik
Categories: cond-mat.other
Comments: 4 pages, 5 figures
\\
A two-dimensional lattice hard-core boson system with a small fraction of
bosonic or fermionic impurity particles is studied. The impurities have the
same hopping and interactions as the dominant bosons and their effects are
solely due to quantum statistics. Quantum Monte Carlo simulations are carried
out in which paths of the dominant boson species are sampled and a summation is
performed over all second-species paths compatible with the permutation cycles.
Both kinds of impurities reduce modestly and equally the Kosterliz-Thouless
superfluid transition temperature. However, the effective impurity interactions
are found to be qualitatively different at lower temperatures; fermions are
repulsive and further suppress superfluidity at low temperatures.
\\ ( http://arxiv.org/abs/0707.1319 , 33kb)
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arXiv:0707.1011 (*cross-listing*)
Date: Fri, 6 Jul 2007 16:46:39 GMT (43kb)

Title: Statistical Phases and Momentum Spacings for One-Dimensional Anyons
Authors: Martin Greiter
Categories: quant-ph cond-mat.str-el math-ph math.MP
Comments: 16 pages, 1 figure
\\
Anyons and fractional statistics are by now well established in
two-dimensional systems. In one dimension, fractional statistics has been
established so far only through Haldane's fractional exclusion principle, but
not via a fractional phase the wave function acquires as particles are
interchanged. At first sight, the topology of the configuration space appears
to preclude such phases in one dimension. Here we argue that the crossings of
one-dimensional anyons are always unidirectional, which makes it possible to
assign phases consistently and hence to introduce a statistical parameter
theta. The fractional statistics then manifests itself in fractional spacings
of the single-particle momenta of the anyons when periodic boundary conditions
are imposed. These spacings are given by Delta p = 2 pi hbar/L
(|theta|/pi+non-negative integer) for a system of length L. This condition is
the analogue of the quantisation of relative angular momenta according to
l_z=hbar(-theta/pi+2integer) for two-dimensional anyons.
\\ ( http://arxiv.org/abs/0707.1011 , 43kb)
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arXiv:0707.1178
Date: Mon, 9 Jul 2007 04:30:32 GMT (701kb,D)

Title: Characterization of EIT-based continuous variable quantum memories
Authors: G. H\'etet, A. Peng, M. T. Johnsson, J. J. Hope, P. K. Lam
Categories: quant-ph
\\
We present a quantum multi-modal treatment describing Electromagnetically
Induced Transparency (EIT) as a mechanism for storing continuous variablequantum
information in light fields. Taking into account the atomic noise
anddecoherences of realistic experiments, we model numerically the
propagation,storage, and readout of signals contained in the sideband amplitude
and phasequadratures of a light pulse. An analytical treatment of the effects
predictedby this more sophisticated model is then presented. Finally, we use
quantum
information benchmarks to examine the properties of the EIT-based memory and
show the parameters needed to operate beyond the quantum limit.
\\ ( http://arxiv.org/abs/0707.1178 , 701kb)
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arXiv:0707.1314
Date: Mon, 9 Jul 2007 19:54:49 GMT (187kb,D)

Title: Fluorescence during Doppler cooling of a single trapped atom
Authors: J. H. Wesenberg, R. J. Epstein, D. Leibfried, R. B. Blakestad, J.
Britton, J. P. Home, W. M. Itano, J. D. Jost, E. Knill, C. Langer, R. Ozeri,
S. Seidelin, D. J. Wineland
Categories: quant-ph
Comments: 12 pages, 11 figures, Submitted to Phys. Rev. A
\\
We investigate the temporal dynamics of Doppler cooling of an initially hot
single trapped atom in the weak binding regime using a semiclassical approach.
We develop an analytical model for the simplest case of a single vibrational
mode for a harmonic trap, and show how this model allows us to estimate the
initial energy of the trapped particle by observing the fluorescence rate
during the cooling process. The experimental implementation of this temperature
measurement provides a way to measure atom heating rates by observing the
temperature rise in the absence of cooling. This method is technically
relatively simple compared to conventiponal sideband detection methods, and the
two methods are in reasonable agreement. We also discuss the effects of RF
micromotion, relevant for a trapped atomic ion, and the effect of coupling
between the vibrational modes on the cooling dynamics.
\\ ( http://arxiv.org/abs/0707.1314 , 187kb)
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arXiv:0707.1357
Date: Tue, 10 Jul 2007 02:07:34 GMT (6kb)

Title: How to extract information about a nanosystem in canonical ensemble from
the larger system in grand canonical ensemble?
Authors: D. S. Kosov, M. F. Gelin and A.I. Vdovin
Categories: cond-mat.stat-mech
\\
We present a method to compute averages in canonical ensemble based on
calculations of the expectation values in grand canonical ensemble. The number
of particles n, which is fixed in the canonical ensemble, is not necessarily
the same as the average number of particles <N> in the grand canonical
ensemble.
\\ ( http://arxiv.org/abs/0707.1357 , 6kb)
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arXiv:0707.1446
Date: Tue, 10 Jul 2007 13:21:19 GMT (105kb)

Title: Excitations and superfluidity in non-equilibrium Bose-Einstein
condensates of exciton-polaritons
Authors: M. Wouters and I. Carusotto
Categories: cond-mat.mes-hall
Comments: 4 pages, 2 figures
\\
We present a generic model for the description of non-equilibrium
Bose-Einstein condensates, suited for the modelling of non-resonantly pumped
polariton condensates in a semiconductor microcavity. The excitation spectrum
and scattering of the non-equilibrium condensate with a defect are discussed.
\\ ( http://arxiv.org/abs/0707.1446 , 105kb)
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arXiv:0707.1465
Date: Tue, 10 Jul 2007 14:36:49 GMT (347kb)

Title: Resonant superradiant backward-scattering as a source for many-particle
entanglement
Authors: K.M.R. van der Stam, R. Meppelink, J.M. Vogels, J.W. Thomsen, and P.
van der Straten
Categories: cond-mat.other
Comments: 5 pages, 6 figures
\\
We investigate the atom pair production by superradiant backward-scattering
from a Bose-Einstein condensate. By driving the superradiant process with two
frequencies we can extend both the range of pulse duration and intensity by two
orders of magnitude and obtain full control over the number of scattered atoms
in forward and backward direction. We show that the atoms scattered in forward
direction are strongly correlated with the atoms scattered in backward
direction, which makes resonant superradiant backward-scattering a promising
candidate for many-particle entanglement.
\\ ( http://arxiv.org/abs/0707.1465 , 347kb)
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arXiv:0707.1520
Date: Wed, 11 Jul 2007 19:02:33 GMT (361kb)

Title: Shear viscosity of a superfluid Fermi gas in the unitarity limit
Authors: Gautam Rupak and Thomas Schaefer
Categories: cond-mat.other
Comments: 9 pages, 7 figures, LaTeX2e
\\
We compute the shear viscosity of a superfluid atomic Fermi gas in the
unitarity limit. The unitarity limit is characterized by a divergent scattering
length between the atoms, and it has been argued that this will result in a
very small viscosity. We show that in the low temperature T limit the shear
viscosity scales as xi^5/T^5, where the universal parameter 'xi' relates the
chemical potential and the Fermi energy, mu=xi E_F. Combined with the high
temperature expansions of the viscosity our results suggest that the viscosity
has a minimum near the critical temperature T_c. A naive extrapolation
indicates that the minimum value of the ratio of viscosity over entropy density
is within a factor of ~ 5 of the proposed lower bound hbar/(4\pi k_B).
\\ ( http://arxiv.org/abs/0707.1520 , 361kb)
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arXiv:0707.1538
Date: Tue, 10 Jul 2007 23:48:25 GMT (9kb)

Title: Transition temperature of the homogeneous, dilute and weakly interacting
Bose gas in D-dimensions
Authors: Sang-Hoon Kim
Categories: cond-mat.stat-mech
Comments: 4 pages, 1 figure
\\
The phase transition temperature of the homogeneous, dilute, and weakly
interacting Bose gas in D-dimensions ($2 < D \le 3$) is calculated by a mean
field method.
We show that when the shift of the leading order is $\Delta T_c/T_c^0 = c \gam^{\al}$, c(D) is positive and $\al(D)=D/2-1$ in the short-wavelength range.
The T_c at D=2 is calculated in the same scheme. The result is compared with
others. The origin of the difference between \al=1/2 and the widely accepted
\al=1 in 3D is discussed.
\\ ( http://arxiv.org/abs/0707.1538 , 9kb)
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arXiv:0707.1649
Date: Wed, 11 Jul 2007 19:19:03 GMT (248kb)

Title: One-dimensional superfluid Bose-Fermi mixture: mixing, demixing and
bright solitons
Authors: Sadhan K. Adhikari and Luca Salasnich
Categories: cond-mat.other
Comments: 11 pages, 11 figures
\\
We study a ultra-cold and dilute superfluid Bose-Fermi mixture confined in a
strictly one-dimensional atomic waveguide by using a set of coupled nonlinear
mean-field equations obtained from the Lieb-Liniger energy density for bosons
and the Gaudin-Yang energy density for fermions. We consider a finite
Bose-Fermi inter-atomic strength $g_{bf}$ and both periodic and open boundary
conditions. We find that with periodic boundary conditions, i.e. in a quasi-1D
ring, a uniform Bose-Fermi mixture is stable only with a large fermionic
density. We predict that at small fermionic densities the ground state of the
system displays demixing if $g_{bf}>0$ and may become a localized Bose-Fermi
bright soliton for $g_{bf}<0$. Finally, we show, using variational and
numerical solution of the mean-field equations, that with open boundary
conditions, i.e. in a quasi-1D cylinder, the Bose-Fermi bright soliton is the
unique ground state of the system with a finite number of particles, which
could exhibit a partial mixing-demixing transition. In this case the bright
solitons are demonstrated to be dynamically stable. The experimental
realization of these Bose-Fermi bright solitons seems possible with present
setups.
\\ ( http://arxiv.org/abs/0707.1649 , 248kb)
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arXiv:0707.1568 (*cross-listing*)
Date: Wed, 11 Jul 2007 06:56:32 GMT (18kb)

Title: Rapidly Rotating Bose-Einstein Condensates in Homogeneous Traps
Authors: M. Correggi, T. Rindler-Daller, J. Yngvason
Categories: math-ph cond-mat.other math.MP
Comments: LaTex2e, 16 pages
MSC-class: 35Q55; 47J30; 76M23
\\
We extend the results of a previous paper on the Gross-Pitaevskii description
of rotating Bose-Einstein condensates in two-dimensional traps to confining
potentials of the form V(r) = r^s, $2<s <\infty$. Writing the coupling constant
as $1/\epsilon^2$ we study the limit $\epsilon \to 0$. We derive rigorously the
leading asymptotics of the ground state energy and the density profile when the
rotation velocity \Omega tends to infinity as a power of $1/\epsilon$. The case
of asymptotically homogeneous potentials is also discussed.
\\ ( http://arxiv.org/abs/0707.1568 , 18kb)
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arXiv:0707.1653
Date: Wed, 11 Jul 2007 16:00:38 GMT (79kb)

Title: Chaos in kicked Bose-Einstein condensates: Bogoliubov resonances
Authors: J. Reslen, C.E. Creffield, and T.S. Monteiro
Categories: quant-ph
Comments: 5 pages
\\
Bose-Einstein condensates (BECs) subject to short pulses (kicks') from
standing waves of light represent a nonlinear analogue of the well-known chaos
paradigm, the quantum kicked rotor (QKR). We investigate condensate
instability, in the sense of exponential proliferation of non-condensate
particles, as a function of the kicking period and nonlinearity. We show that
Bogoliubov resonances play a key role in the onset of instability. For low kick
strengths they are isolated, and there is no single instability threshold: the
condensate loses, then recovers stability around a few isolated resonances. For
stronger kicks, multiple resonances contribute and we identify the BEC analogue
of the overlapping of resonances'' criterion of chaos, beyond which the
condensate is in general exponentially unstable. In addition to the standard
QKR, we study a more stable variant involving pairs of opposing kicks, and
compare and contrast their behavior. An analytical model for low-order
resonances, which accounts for their characteristic scaling properties, is
presented.
\\ ( http://arxiv.org/abs/0707.1653 , 79kb)
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arXiv:0707.1751
Date: Thu, 12 Jul 2007 10:08:14 GMT (491kb)

Title: Thermodynamics and superfluid density in BCS-BEC crossover with and
without population imbalance
Authors: Yan He, Chih-Chun Chien, Qijin Chen, and K. Levin
Categories: cond-mat.str-el cond-mat.supr-con
Comments: 19 pages, 14 figures. Submitted to PRB
\\
We address the thermodynamics, density profiles and superfluid density of
trapped fermions undergoing BCS-BEC crossover, with and without population
imbalance. Our approach represents a fully consistent treatment of "pseudogap
effects", which reflect the distinction between the pair formation temperature
$T^*$ and the pair condensation temperature $T_c$ and must be accommodated by
modifying the fermionic excitation spectrum. This distinction has been omitted
from all other many body approaches in the literature. We show how enforcing
this corollary implies that pairing fluctuation contributions enter into both
the gap and the number equations; this is necessary in order to be consistent
with a generalized Ward identity. Furthermore, we demonstrate that we obtain
physical results for the superfluid density $n_s(T)$ at all $T$. In contrast,
previous work in the literature has led to ill-behaved $n_s(T)$. The superfluid
density is a critical measure of the physicality of a given crossover theory.
In order to properly address thermodynamic properties of a trapped Fermi gas,
it is necessary to demonstrate that the particle density profiles are
consistent with experiment. The lack of demonstrable consistency between
theoretical and experimental density profiles, along with problematic behavior
found for $n_s(T)$, casts doubt on previous claims in the literature concerning
quantitative agreement between thermodynamical calculations and experiment.
\\ ( http://arxiv.org/abs/0707.1751 , 491kb)
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arXiv:0707.1830
Date: Thu, 12 Jul 2007 16:12:57 GMT (258kb)

Title: Nonlinear transport of Bose-Einstein condensates through mesoscopic
waveguides
Authors: Tobias Paul, Michael Hartung, Klaus Richter, and Peter Schlagheck
Categories: cond-mat.other
Comments: 23 pages, 16 figures
\\
We study the coherent flow of interacting Bose-condensed atoms in mesoscopic
waveguide geometries. Analytical and numerical methods, based on the mean-field
description of the condensate, are developed to study both stationary as well
as time-dependent propagation processes. We apply these methods to the
propagation of a condensate through an atomic quantum dot in a waveguide,
discuss the nonlinear transmission spectrum and show that resonant transport is
generally suppressed due to an interaction-induced bistability phenomenon.
Finally, we establish a link between the nonlinear features of the transmission
spectrum and the self-consistent quasi-bound states of the quantum dot.
\\ ( http://arxiv.org/abs/0707.1830 , 258kb)
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arXiv:0707.1851
Date: Thu, 12 Jul 2007 18:21:20 GMT (8kb)

Title: Three comments on the Fermi gas at unitarity in a harmonic trap
Authors: D.T.Son
Categories: cond-mat.other
Comments: 6 pages, 1 figure
Report-no: INT-PUB 07-12
\\
In this note we consider three issues related to the unitary Fermi gas in a
harmonic trap. We present a short proof of a virial theorem, which states that
the average energy of a particle system at unitarity in a harmonic trap is
twice larger than the average potential energy. The theorem is valid for all
systems with no intrinsic scale, at zero or finite temperature. We discuss the
odd-even splitting in a unitarity Fermi gas in a harmonic trap. We show that at
large number of particles N the odd-even splitting is proportional to
N^{1/9}\hbar\omega, with an undetermined numerical constant. We also show that
for odd N the lowest excitation energies are of order N^{-1/3}\hbar\omega.
\\ ( http://arxiv.org/abs/0707.1851 , 8kb)
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arXiv:0707.1703
Date: Wed, 11 Jul 2007 20:38:46 GMT (357kb)

Title: Trapping of Neutral Rubidium with a Macroscopic Three-Phase Electric
Trap
Authors: T. Rieger, P. Windpassinger, S.A. Rangwala, G. Rempe, P.W.H. Pinkse
Categories: physics.atom-ph
Comments: 4 pages, 4 figures
\\
We trap neutral ground-state rubidium atoms in a macroscopic trap based on
purely electric fields. For this, three electrostatic field configurations are
alternated in a periodic manner. The rubidium is precooled in a magneto-optical
trap, transferred into a magnetic trap and then translated into the electric
trap. The electric trap consists of six rod-shaped electrodes in cubic
arrangement, giving ample optical access. Up to 10^5 atoms have been trapped
with an initial temperature of around 20 microkelvin in the three-phase
electric trap. The observations are in good agreement with detailed numerical
simulations.
\\ ( http://arxiv.org/abs/0707.1703 , 357kb)
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The replacements:

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arXiv:cond-mat/0610623
replaced with revised version Fri, 6 Jul 2007 14:12:25 GMT (31kb)

Title: A number-conserving approach to a minimal self-consistent treatment of
condensate and non-condensate dynamics in a degenerate Bose gas
Authors: S. A. Gardiner and S.A. Morgan
Categories: cond-mat.other
Comments: 20 pages. Equation (71) is corrected. An erratum will appear in Phys.
Rev. A
Journal-ref: Phys. Rev. A 75, 043621 (2007)
DOI: 10.1103/PhysRevA.75.043621
\\ ( http://arxiv.org/abs/cond-mat/0610623 , 31kb)
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\\
arXiv:cond-mat/0507108
replaced with revised version Sat, 7 Jul 2007 03:20:18 GMT (603kb)

Title: Noise Correlations in one-dimensional systems of ultra-cold fermions
Authors: L.Mathey, E.Altman and A.Vishwanath
Categories: cond-mat.str-el cond-mat.other
Comments: 5 pages, 3 figures. Added discussion on the visibility of noise
correlation features for realistic conditions
\\ ( http://arxiv.org/abs/cond-mat/0507108 , 603kb)
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arXiv:quant-ph/0703199
replaced with revised version Mon, 9 Jul 2007 18:02:50 GMT (706kb)

Title: Bose-Einstein condensate coupled to a nanomechanical resonator on an
atom chip: a proposal
Authors: Philipp Treutlein, David Hunger, Stephan Camerer, Theodor W. H\"ansch,
and Jakob Reichel
Categories: quant-ph
Comments: 5 pages, 3 figures
\\ ( http://arxiv.org/abs/quant-ph/0703199 , 706kb)
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\\
arXiv:quant-ph/0703157
replaced with revised version Mon, 9 Jul 2007 13:19:02 GMT (40kb)

Title: Cavity cooling of internal molecular motion
Authors: Giovanna Morigi, Pepijn W.H. Pinkse, Markus Kowalewski, and Regina de
Vivie-Riedle
Categories: quant-ph physics.atom-ph
Comments: 4 pages, 4 figures. To appear in Physical Review Letters
\\ ( http://arxiv.org/abs/quant-ph/0703157 , 40kb)
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\\
arXiv:0706.4041
replaced with revised version Tue, 10 Jul 2007 13:51:58 GMT (963kb)

Title: Matter-wave Interferometry with Phase Fluctuating Bose-Einstein
Condensates
Authors: G.-B. Jo, J.-H. Choi, C.A. Christensen, Y.-R. Lee, T.A. Pasquini, W.
Ketterle, and D.E. Pritchard
Categories: cond-mat.other
Comments: 4 pages, 5 figures, figures corrected
\\ ( http://arxiv.org/abs/0706.4041 , 963kb)
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arXiv:cond-mat/0602108
replaced with revised version Tue, 10 Jul 2007 11:47:33 GMT (323kb)

Title: Supersonic optical tunnels for Bose-Einstein condensates
Authors: S. Wuester and B. J. Dabrowska-Wuester
Categories: cond-mat.other
Comments: 14 pages, 3 figures, published version
Journal-ref: New Journal of Physics, 9 (2007) 85
\\ ( http://arxiv.org/abs/cond-mat/0602108 , 323kb)
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arXiv:cond-mat/0609417
replaced with revised version Tue, 10 Jul 2007 12:19:40 GMT (48kb)

Title: Quantum depletion of collapsing Bose-Einstein condensates
Authors: S. Wuester, B. J. Dabrowska-Wuester, A. S. Bradley, M. J. Davis, P. B.
Blakie, J. J. Hope and C. M. Savage
Categories: cond-mat.other
Comments: 9 pages, 4 figures, replaced with published version
Journal-ref: Phys. Rev. A 75 (2007) 043611
\\ ( http://arxiv.org/abs/cond-mat/0609417 , 48kb)
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arXiv:cond-mat/0702045
replaced with revised version Tue, 10 Jul 2007 12:09:03 GMT (161kb)

Title: Limits to the analogue Hawking temperature in a Bose-Einstein condensate
Authors: S. Wuester and C.M. Savage
Categories: cond-mat.other
Comments: 9 pages, 4 figures, replaced with published version
Journal-ref: Phys. Rev. A 76 (2007) 013608
\\ ( http://arxiv.org/abs/cond-mat/0702045 , 161kb)
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arXiv:cond-mat/0703433
replaced with revised version Tue, 10 Jul 2007 16:42:32 GMT (34kb)

Title: Spin-polarized Fermi superfluids as Bose-Fermi mixtures
Authors: E. Taylor, A. Griffin, and Y. Ohashi
Categories: cond-mat.other
Comments: The expurgated version; accepted for publication in PRA
\\ ( http://arxiv.org/abs/cond-mat/0703433 , 34kb)
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arXiv:0707.0675
replaced with revised version Wed, 11 Jul 2007 14:35:57 GMT (265kb)

Title: Disorder-Induced Order in Two-Component Bose-Einstein Condensates
Authors: Armand Niederberger, Thomas Schulte, Jan Wehr, Maciej Lewenstein,
Laurent Sanchez-Palencia, Krzysztof Sacha
Categories: cond-mat.other cond-mat.dis-nn
Comments: 4 pages, 3 figures
\\ ( http://arxiv.org/abs/0707.0675 , 265kb)
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arXiv:0704.0912
replaced with revised version Tue, 10 Jul 2007 21:40:22 GMT (510kb)

Title: Nuclear Spin Effects in Optical Lattice Clocks
Authors: Martin M. Boyd, Tanya Zelevinsky, Andrew D. Ludlow, Sebastian Blatt,
Thomas Zanon-Willette, Seth M. Foreman and Jun Ye
Categories: physics.atom-ph
Comments: 13 pages, 12 figures, submitted to PRA
\\ ( http://arxiv.org/abs/0704.0912 , 510kb)
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arXiv:quant-ph/0609225 (*cross-listing*)
replaced with revised version Thu, 12 Jul 2007 03:34:30 GMT (820kb)

Title: Generating squeezing in an atom laser through self-interaction
Authors: Mattias T. Johnsson and Simon A. Haine
Categories: quant-ph cond-mat.other
Comments: v2. Incorporates changes due to referees' comments. We also
demonstrate that our scheme generates number squeezing as well as quadrature
squeezing
Journal-ref: Phys. Rev. Lett. 99, 010401 (2007)
\\ ( http://arxiv.org/abs/quant-ph/0609225 , 820kb)
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Till next time,
Matt.

--
=========================================================================
Dr M. J. Davis,               Senior Lecturer in Physics
School of Physical Sciences,  email: mdavis_at_physics.uq.edu.au
University of Queensland,     ph   : +61 7 334 69824
Brisbane, QLD 4072,           fax  : +61 7 336 51242
Australia.                    http://www.physics.uq.edu.au/people/mdavis/
=========================================================================
Matt's arXiv selection: weekly summary of cold-atom papers from arXiv.org
http://www.physics.uq.edu.au/people/mdavis/matts_arXiv/
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Received on Wed Jul 25 2007 - 17:55:23 EST

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