Dear subscribers,
This week we thank Jacopo Sabbatini. There are 24 new preprints and 5 replacements:
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arXiv:0906.1110
Date: Fri, 5 Jun 2009 12:37:14 GMT (551kb,D)
Title: Dynamical creation of a supersolid in asymmetric mixtures of bosons
Authors: Tassilo Keilmann, J. Ignacio Cirac and Tommaso Roscilde
Categories: cond-mat.quant-gas
Comments: Accepted at Phys. Rev. Lett
\\
We propose a scheme to dynamically create a supersolid state in an optical
lattice, using an attractive mixture of mass-imbalanced bosons. Starting from a
"molecular" quantum crystal, supersolidity is induced dynamically as an
out-of-equilibrium state. When neighboring molecular wavefunctions overlap,
both bosonic species simultaneously exhibit quasi-condensation and long-range
solid order, which is stabilized by their mass imbalance. Supersolidity appears
in a perfect one-dimensional crystal, without the requirement of doping. Our
model can be realized in present experiments with bosonic mixtures that feature
simple on-site interactions, clearing the path to the observation of
supersolidity.
\\ ( http://arxiv.org/abs/0906.1110 , 551kb)
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arXiv:0906.1161
Date: Fri, 5 Jun 2009 16:18:28 GMT (34kb)
Title: Adiabatic dynamics in passage through a quantum critical point and
gapless phases
Authors: Debanjan Chowdhury, Uma Divakaran and Amit Dutta
Categories: cond-mat.stat-mech
Comments: 5 pages, 3 figures
\\
It is well known that the dynamics of a quantum system is always
non-adiabatic in passage through a quantum critical point and the defect
density in the final state following a quench shows a power-law decay with the
rate of quenching. We here propose a possible scenario of the adiabatic
dynamics of a quantum system even in passage through quantum critical points.
This is achieved by incorporating additional interactions which lead to quantum
critical behavior and gapless phases but do not participate in the time
evolution of the system. To illustrate the general argument, we study the
defect generation in the quantum critical dynamics of a spin-1/2 anisotropic
quantum XY spin chain with three spin interactions and a staggered magnetic
field. The system is driven by changing the staggered magnetic field linearly
with time $t$ as $t/\tau$ where $1/\tau$ determines the rate of quenching. In
the process, the system is swept across a quantum critical line followed by
gapless regions. We show that the density of defects in the final state after
the quenching scales as $1/\sqrt{\tau}$ if the strength of XY interaction
between the spins on even and odd sublattices is the same as the interaction
between the spins on odd and even sublattices. On the other hand, if these
interactions are different, the density of defects vanish exponentially with
$\tau$ contradicting the generic power-law scaling even though the system is
quenched across quantum critical lines and gapless phases in either cases.
\\ ( http://arxiv.org/abs/0906.1161 , 34kb)
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arXiv:0906.1031
Date: Fri, 5 Jun 2009 02:25:16 GMT (87kb,D)
Title: Continuous measurement feedback control of a Bose-Einstein condensate
using phase contrast imaging
Authors: S. S. Szigeti, M. R. Hush, A. R. R. Carvalho and J. J. Hope
Categories: quant-ph
Comments: 4 figures, 11 pages, submitted to PRA
\\
We consider the theory of feedback control of a Bose-Einstein condensate
(BEC) confined in a harmonic trap under a continuous measurement constructed
via non-destructive imaging. A filtering theory approach is used to derive a
stochastic master equation (SME) for the system from a general Hamiltonian
based upon system-bath coupling. Numerical solutions for this SME in the limit
of a single atom show that the final steady state energy is dependent upon the
measurement strength, the ratio of photon kinetic energy to atomic kinetic
energy, and the feedback strength. Simulations indicate that for a weak
measurement strength, feedback can be used to overcome heating introduced by
the scattering of light, thereby allowing the atom to be driven towards the
ground state.
\\ ( http://arxiv.org/abs/0906.1031 , 87kb)
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arXiv:0906.1239
Date: Sat, 6 Jun 2009 01:03:11 GMT (18kb)
Title: On the kinetic energy of unitary Fermi gas in a harmonic trap
Authors: Alexander L. Zubarev and Michael Zoubarev
Categories: cond-mat.quant-gas
Comments: 12 pages, 3 figures
\\
We have considered the orbital-free approximation of the kinetic energy
functional to investigate the zero temperature properties of dilute
harmonically trapped two component Fermi gas at unitarity. It is shown that our
approach provides a realible and inexpensive method to study superfluid
strongly interacting dilute Fermi gases.
\\ ( http://arxiv.org/abs/0906.1239 , 18kb)
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arXiv:0906.1337
Date: Sun, 7 Jun 2009 09:56:15 GMT (199kb,X)
Title: A sonic black hole in a density-inverted Bose-Einstein condensate
Authors: O. Lahav, A. Itah, A. Blumkin, C. Gordon, and J. Steinhauer
Categories: cond-mat.quant-gas
\\
We have created the analogue of a black hole in a Bose-Einstein condensate.
In this sonic black hole, sound waves, rather than light waves, cannot escape
the event horizon. The black hole is realized via a counterintuitive density
inversion, in which an attractive potential repels the atoms. This allows for
measured flow speeds which cross and exceed the speed of sound by an order of
magnitude. The Landau critical velocity is therefore surpassed. The point where
the flow speed equals the speed of sound is the event horizon. The effective
gravity is determined from the profiles of the velocity and speed of sound.
\\ ( http://arxiv.org/abs/0906.1337 , 199kb)
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arXiv:0906.1376
Date: Sun, 7 Jun 2009 18:45:02 GMT (8kb)
Title: Solution of the Stochastic Langevin Equations for Clustering of
Particles in Turbulent Flows in Terms of Wiener Path Integral
Authors: M. Chaichian, A. Tureanu, A. Zahabi
Categories: cond-mat.stat-mech
Comments: 11 pages
Report-no: HIP-2009-16/TH
\\
We present the solution for the joint probability densities of particles
suspended in a fluid under the effect of viscous and random forces, in terms of
the Wiener path integral. Our obtained exact solution, giving the expression
for the Lyapunov exponent, i) will provide the description of all the features
and the behaviour of such a system, e.g. the aggregation phenomenon recently
studied in the literature using certain approximations, ii) can be used to
determine the occurrence and the nature of the aggregation - non-aggregation
phase transition and iii) allows the use of a variety of approximation methods
appropriate for the physical conditions of the problem.
\\ ( http://arxiv.org/abs/0906.1376 , 8kb)
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arXiv:0906.1600
Date: Mon, 8 Jun 2009 21:04:55 GMT (717kb)
Title: Frustrated Bose condensates in optical lattices
Authors: T. Duric, D. K. K. Lee
Categories: cond-mat.quant-gas
Comments: 10 pages, 9 figures
\\
We study the Bose-condensed ground states of bosons in an optical lattice in
the presence of frustration due to an effective vector potential, for example,
due to lattice rotation. We use a mapping to a large-S frustrated magnet to
study quantum fluctuations in the condensed state. Quantum fluctuations are
introduced by considering a 1/S expansion around the classical ground state.
The results show that, within the large-S approach, the superfluid fraction and
the condensate fraction do not vanish even at the critical value of the
chemical potential where the system becomes a Mott insulator. However, for
cases with fewer than 1/3 flux quantum per lattice plaquette, we find that the
condensate depletion increases as the system approaches the Mott phase, giving
rise to the possibility of a non-condensed state before the Mott phase is
reached.
\\ ( http://arxiv.org/abs/0906.1600 , 717kb)
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arXiv:0906.1686
Date: Tue, 9 Jun 2009 10:31:43 GMT (24kb)
Title: Quantum entanglement of spin-1 bosons with coupled ground states in
optical lattices
Authors: B. \"Oztop, M. \"O. Oktel, \"O. E. M\"ustecapl\i o\u{g}lu and L. You
Categories: cond-mat.quant-gas
Comments: 18 pages, 8 figures. To be published in Journal of Physics B
\\
We examine particle entanglement, characterized by pseudo-spin squeezing, of
spin-1 bosonic atoms with coupled ground states in a one-dimensional optical
lattice. Both the superfluid and Mott-insulator phases are investigated
separately for ferromagnetic and antiferromagnetic interactions. Mode
entanglement is also discussed in the Mott insulating phase. The role of a
small but nonzero angle between the polarization vectors of counter-propagating
lasers forming the optical lattice on quantum correlations is investigated as
well.
\\ ( http://arxiv.org/abs/0906.1686 , 24kb)
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arXiv:0906.1765
Date: Tue, 9 Jun 2009 19:38:23 GMT (215kb)
Title: Non-destructive cavity QED probe of Bloch oscillations in a gas of
ultracold atoms
Authors: B. M. Peden, D. Meiser, M. L. Chiofalo, M. J. Holland
Categories: cond-mat.quant-gas
Comments: 8 pages, 6 figures, submitted to Phys. Rev. A
\\
We describe a scheme for probing a gas of ultracold atoms trapped in an
optical lattice and moving in the presence of an external potential. The probe
is non-destructive and uses the existing lattice fields as the measurement
device. Two counter-propagating cavity fields simultaneously set up a
conservative lattice potential and a weak quantum probe of the atomic motion.
Balanced heterodyne detection of the probe field at the cavity output along
with integration in time and across the atomic cloud yield information about
the atomic dynamics in a single run. The scheme is applied to a measurement of
the Bloch oscillation frequency for atoms moving in the presence of the local
gravitational potential. Signal-to-noise ratios are estimated to be as high as
$10^4$.
\\ ( http://arxiv.org/abs/0906.1765 , 215kb)
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arXiv:0906.1801
Date: Tue, 9 Jun 2009 18:52:55 GMT (106kb)
Title: Signature of the FFLO phase in the collective modes of a trapped
ultracold Fermi gas
Authors: Jonathan M. Edge, N.R. Cooper
Categories: cond-mat.quant-gas
Comments: 5 pages, 3 figures
\\
We study theoretically the collective modes of a two-component Fermi gas with
attractive interactions in a quasi-one-dimensional harmonic trap. We focus on
an imbalanced gas in the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase. Using a
mean-field theory, we study the response of the ground state to time-dependent
potentials. For potentials with short wavelengths, we find dramatic signatures
in the large-scale response of the gas which are characteristic of the FFLO
phase. This response provides an effective way to detect the FFLO state in
experiments.
\\ ( http://arxiv.org/abs/0906.1801 , 106kb)
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arXiv:0906.0333 (*cross-listing*)
Date: Mon, 1 Jun 2009 18:20:36 GMT (107kb)
Title: Critical point of the two-dimensional Bose gas: an S-matrix approach
Authors: Pye-Ton How and Andre' LeClair
Categories: math-ph cond-mat.quant-gas math.MP
Comments: 32 pages
\\
A new treatment of the critical point of the two-dimensional interacting Bose
gas is presented. In the lowest order approximation we obtain the critical
temperature T_c ~ 2 \pi n/[ m \log (2\pi/mg)], where n is the density, m the
mass, and g the coupling. This result is based on a new formulation of
interacting gases at finite density and temperature which is reminiscent of the
thermodynamic Bethe ansatz in one dimension. In this formalism, the basic
thermodynamic quantities are expressed in terms of a pseudo-energy. Consistent
resummation of 2-body scattering leads to an integral equation for the
pseudo-energy with a kernel based on the logarithm of the exact 2-body
S-matrix.
\\ ( http://arxiv.org/abs/0906.0333 , 107kb)
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arXiv:0906.1625
Date: Tue, 9 Jun 2009 02:19:23 GMT (121kb)
Title: On the Control of Tripod-Scheme Cold-Atom Wavepackets by non-Abelian
Geometric Phases
Authors: Qi Zhang, Jiangbin Gong, and C.H. Oh
Categories: quant-ph
Comments: 22 pages, 4 figures, submitted to Phys. Rev. A
\\
Tripod-scheme cold atoms interacting with laser beams have attracted
considerable interest for their role in synthesizing effective non-Abelian
vector potentials. Such effective vector potentials are exploited in our recent
work to realize an all-optical imprinting of geometric phases onto matter waves
[Zhang, Gong, and Oh, Phys. Rev. A 79, 043632 (2009)]. By working with two
specific laser beam displacement scenarios for the generation of geometric
phases and for the control of matter wave propagation, we demonstrate that a
geometric phase may be understood as a dynamical phase and a non-Abelian
geometric phase maybe understood as an effective Abelian geometric phase by
changing the frame of reference. Results enhance our understanding of geometric
phases as a fundamental element in quantum mechanics and help design better
schemes for the imprinting of geometric phases.
\\ ( http://arxiv.org/abs/0906.1625 , 121kb)
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arXiv:0906.1894
Date: Wed, 10 Jun 2009 09:23:32 GMT (324kb)
Title: Two-photon nonlinear spectroscopy of periodically trapped ultracold
atoms in a cavity
Authors: Tarun Kumar, Aranya B Bhattacherjee and ManMohan
Categories: cond-mat.quant-gas
Comments: 6 pages and 5 figures
\\
We study the transmission spectra of a Bose Einstein condensate confined in
an optical lattice interacting with two modes of a cavity via nonlinear
two-photon transition. In particular we show that a nonlinear two-photon
interaction between the superfluid (SF) phase and the Mott insulating (MI)
phase of a Bose-Einstein condensate (BEC) and the cavity field show
qualitatively different transmission spectra compared to the one-photon
interaction. We found that when the BEC is in the Mott state, the usual normal
mode splitting present in the one-photon transition is missing in the
two-photon interaction. When the BEC is in the superfluid state, the
transmission spectra shows the usual multiple lorentzian structure. However the
separation between the lorentzians for the two-photon case is much larger than
that for the one-photon case. This study could form the basis for
non-destructive high resolution Rydberg spectroscopy of ultracold atoms or
two-photon spectroscopy of a gas of ultracold atomic hydrogen.
\\ ( http://arxiv.org/abs/0906.1894 , 324kb)
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arXiv:0906.1937
Date: Wed, 10 Jun 2009 13:53:25 GMT (239kb)
Title: Polarized Fermi gases in asymmetric optical lattices
Authors: Xiaoling Cui and Yupeng Wang
Categories: cond-mat.quant-gas cond-mat.supr-con
Comments: 8 pages, 7 figures
\\
We present the zero temperature phase diagrams of imbalanced two species
fermions in asymmetric optical lattices, based on the exact spectrum rather
than the Fermi-Hubbard model. The crossover of the system from free 3D to
quasi-2D or quasi-1D can be driven by increasing the lattice potential along
one or two directions. We investigate the influence of lattices to the BCS
state, Sarma or breached pair state, normal state, phase separation and
particularly Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state. With fixed s-wave
interactions and given dimension, the strength of FFLO state can be tuned by
both the lattice potentials and particle densities. Compared with a 3D free
Fermi gas, the system with reduced dimensionality by optical lattices is found
to be much more favorable to FFLO pairing. The effect of asymmetric optical
lattices on the phase profile in a harmonic trap is also studied by using LDA.
\\ ( http://arxiv.org/abs/0906.1937 , 239kb)
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arXiv:0906.1640 (*cross-listing*)
Date: Tue, 9 Jun 2009 06:12:03 GMT (1045kb,D)
Title: An introduction to effective low-energy Hamiltonians in condensed matter
physics and chemistry
Authors: B. J. Powell
Categories: physics.chem-ph cond-mat.quant-gas cond-mat.stat-mech
cond-mat.str-el
Comments: 27 pages, 16 figures
\\
These lecture notes introduce some simple effective Hamiltonians (also known
as semi-empirical models) that have widespread applications to solid state and
molecular systems. They are aimed as an introduction to a beginning graduate
student. I also hope that it may help to break down the divide between the
physics and chemistry literatures. After a brief introduction to second
quantisation notation, which is used extensively, I focus of the "four H's":
the Huckel (or tight binding), Hubbard, Heisenberg and Holstein models. Some
other related models, such as the Pariser-Parr-Pople model, the extended
Hubbard model, multi-orbital models and the ionic Hubbard model, are also
discussed. Finally, I discuss the epistemological basis of effective
Hamiltonians and compare and contrast this with that of ab initio methods as
well as discussing the problem of parametrising effective Hamiltonians.
\\ ( http://arxiv.org/abs/0906.1640 , 1045kb)
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arXiv:0906.1968
Date: Wed, 10 Jun 2009 16:10:36 GMT (32kb)
Title: Delirium Quantum
Authors: Christopher A. Fuchs
Categories: quant-ph
Comments: Stuffed away in a conference proceedings for years, I finally worked
up the nerve to post this because I needed to cite it in a paper with some
proper equations. Stay posted
Journal-ref: AIP Conference Proceedings 889, Foundations of Probability and
Physics -- 4, G. Adenier et al eds., (American Institute of Physics,
Melville, NY, 2007), pp. 438-462
\\
This pseudo-paper consists of excerpts drawn from two of my quantum-email
samizdats. Section 1 draws a picture of a physical world whose essence is
``Darwinism all the way down.'' Section 2 outlines how quantum theory should be
viewed in light of this, i.e., as being an expression of probabilism (in Bruno
de Finetti or Richard Jeffrey's sense) all the way back up. Section 3 describes
how the idea of ``identical'' quantum measurement outcomes, though sounding
atomistic in character, nonetheless meshes well with a Jamesian style ``radical
pluralism.'' Sections 4 and 5 further detail how quantum theory should not be
viewed so much as a ``theory of the world,'' but rather as a theory of
decision-making for agents immersed within a world of a particular
character--the quantum world. Finally, Sections 6 and 7 attempt to sketch the
very positive sense in which quantum theory is incomplete, but still just as
complete is it can be. In total, I hope these heady speculations convey some of
the excitement and potential I see for the malleable world quantum mechanics
hints of.
\\ ( http://arxiv.org/abs/0906.1968 , 32kb)
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arXiv:0906.2110
Date: Thu, 11 Jun 2009 14:00:58 GMT (1305kb)
Title: Number Fluctuations and Energy Dissipation in Sodium Spinor Condensates
Authors: Yingmei Liu, Eduardo Gomez, Stephen E. Maxwell, Lincoln D. Turner,
Eite Tiesinga and Paul D. Lett
Categories: cond-mat.other
Journal-ref: Phys. Rev. Lett. 102, 225301 (2009)
\\
We characterize fluctuations in atom number and spin populations in F=1
sodium spinor condensates. We find that the fluctuations enable a quantitative
measure of energy dissipation in the condensate. The time evolution of the
population fluctuations shows a maximum. We interpret this as evidence of a
dissipation-driven separatrix crossing in phase space. For a given initial
state, the critical time to the separatrix crossing is found to depend
exponentially on the magnetic field and linearly on condensate density. This
crossing is confirmed by tracking the energy of the spinor condensate as well
as by Faraday rotation spectroscopy. We also introduce a phenomenological model
that describes the observed dissipation with a single coefficient.
\\ ( http://arxiv.org/abs/0906.2110 , 1305kb)
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arXiv:0906.2115
Date: Thu, 11 Jun 2009 14:21:08 GMT (880kb)
Title: Unconventional superfluidity in Bose-Fermi Mixtures
Authors: O. Dutta and M. Lewenstein
Categories: cond-mat.quant-gas cond-mat.supr-con
\\
Pairing between fermions that attract each other, reveal itself to the
macroscopic world in the form of superfluidity. Since the discovery of
fermionic superfluidity, intense search has been going on to find various
unconventional forms of fermion pairing as well as to increase the transition
temperature. Here, we show that a two dimensional mixture of single-component
fermions and dipolar bosons allows to reach experimentally feasible superfluid
transition temperatures for non-standard pairing symmetries. Excitations in
these superfluids are anyonic and their statistics depends on the order of
their permutations, i.e is non-Abelian. Our results provide for the first time
an example of a highly tunable system which exhibits various kind of pairing
symmetry and high transition temperature. Additionally, they provide a
playground to observe anyonic excitations and their braiding properties.
\\ ( http://arxiv.org/abs/0906.2115 , 880kb)
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arXiv:0906.2126
Date: Thu, 11 Jun 2009 14:56:34 GMT (262kb)
Title: Supersolid phase with cold polar molecules on a triangular lattice
Authors: L. Pollet, J. D. Picon, H.P. Buechler, M. Troyer
Categories: cond-mat.stat-mech cond-mat.quant-gas
Comments: 4 pages, 4 figures
\\
We study a system of heteronuclear molecules on a triangular lattice and
analyze the potential of this system for the experimental realization of a
supersolid phase. The ground state phase diagram contains superfluid, solid and
supersolid phases. At finite temperatures and strong interactions there is an
additional emulsion region, in contrast to similar models with short-range
interactions. We derive the maximal critical temperature $T_c$ and the
corresponding entropy $S/N = 0.04(1)$ for supersolidity and find feasible
experimental conditions for its realization.
\\ ( http://arxiv.org/abs/0906.2126 , 262kb)
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arXiv:0906.2141
Date: Thu, 11 Jun 2009 15:50:09 GMT (166kb)
Title: Fermions in 2D Optical Lattices: Temperature and Entropy Scales for
Observing Antiferromagnetism and Superfluidity
Authors: Thereza Paiva, Richard Scalettar, Mohit Randeria, and Nandini Trivedi
Categories: cond-mat.quant-gas cond-mat.str-el
Comments: 4 pages, 4 figures
\\
One of the major challenges in realizing antiferromagnetic and superfluid
phases in optical lattices is the ability to cool fermions. We determine
constraints on the entropy for observing these phases in two-dimensional
Hubbard models. We investigate antiferromagnetic correlations in the repulsive
model at half filling and superfluidity of s-wave pairs in the attractive case
away from half filling using determinantal quantum Monte Carlo simulations that
are free of the fermion sign problem. We find that an entropy per particle
~log(2) is sufficient to observe the charge gap in the repulsive Hubbard model
or the pairing pseudogap in the attractive case. Observing antiferromagnetic
correlations or superfluidity in 2D systems requires a further reduction in
entropy by a factor of three or more. In contrast to higher dimensions, we find
that adiabatic cooling is not useful to achieve the required low temperatures.
We also show that double occupancy measurements are useful for thermometry for
temperatures greater than the nearest-neighbor hopping.
\\ ( http://arxiv.org/abs/0906.2141 , 166kb)
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arXiv:0906.2150
Date: Thu, 11 Jun 2009 17:18:45 GMT (764kb)
Title: Counterflow and paired superfluidity in one-dimensional Bose mixtures in
optical lattices
Authors: Anzi Hu, L. Mathey, Ippei Danshita, Eite Tiesinga, Carl J. Williams
and Charles W. Clark
Categories: cond-mat.quant-gas
Comments: 13 pages,13 figures
\\
We study the quantum phases of mixtures of ultra-cold bosonic atoms held in
an optical lattice that confines motion or hopping to one spatial dimension.
The phases are found by using Tomonaga-Luttinger liquid theory as well as the
numerical method of time evolving block decimation (TEBD). We consider a binary
mixture with repulsive intra-species interactions, and either repulsive or
attractive inter-species interaction. For a homogeneous system, we find paired-
and counterflow-superfluid phases at different filling and hopping energies. We
also predict parameter regions in which these types of superfluid order coexist
with charge density wave order. We show that the Tomonaga-Luttinger liquid
theory and TEBD qualitatively agree on the location of the phase boundary to
superfluidity. We then describe how these phases are modified and can be
detected when an additional harmonic trap is present. In particular, we show
how experimentally measurable quantities, such as time-of-flight images and the
structure factor, can be used to distinguish the quantum phases. Finally, we
suggest applying a Feshbach ramp to detect the paired superfluid state, and a
$\pi/2$ pulse followed by Bragg spectroscopy to detect the counterflow
superfluid phase.
\\ ( http://arxiv.org/abs/0906.2150 , 764kb)
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arXiv:0906.2174
Date: Thu, 11 Jun 2009 18:20:34 GMT (1021kb)
Title: Angular collapse of dipolar Bose-Einstein condensates
Authors: Ryan M. Wilson, Shai Ronen and John L. Bohn
Categories: cond-mat.quant-gas cond-mat.stat-mech
Comments: 19 pages (preprint), 6 figure, submitted to PRA
\\
We explore the structure and dynamics of dipolar Bose-Einstein condensates
(DBECs) near their threshold for instability. Near this threshold a DBEC may
exhibit nontrivial, biconcave density distributions, which are associated with
instability against collapse into ``angular roton'' modes. Here we discuss
experimental signatures of these novel features. In the first, we infer local
collapse of the DBEC from the experimental stability diagram. In the second, we
explore the dynamics of collapse and find that a nontrivial angular
distribution is a signature of the DBEC possessing a biconcave structure.
\\ ( http://arxiv.org/abs/0906.2174 , 1021kb)
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arXiv:0906.2019 (*cross-listing*)
Date: Wed, 10 Jun 2009 21:20:08 GMT (1465kb,D)
Title: Bose-Einstein Condensation of strongly interacting bosons: from liquid
${}^4$He to QCD monopoles
Authors: Marco Cristoforetti and Edward Shuryak
Categories: hep-ph cond-mat.stat-mech
\\
Starting from classic work of Feynman on the $\lambda$-point of liquid
Helium, we show that his idea of universal action per particle at the BEC
transition point is much more robust that it was known before. Using a simple
"moving string model" for supercurrent and calculating the action, both
semiclassically and numerically, we show that the critical action is the same
for noninteracting and strongly interacting systems such as liquid ${}^4$He.
Inversely, one can obtain accurate dependence of critical temperature on
density: one important consequence is that high density (solid) He cannot be a
BEC state of He atoms, with upper density accurately matching the observations.
We then use this model for the deconfinement phase transition of QCD-like gauge
theories, treated as BEC of (color)magnetic monopoles. We start with
Feynman-like approach without interaction, estimating the monopole mass at
$T_c$. Then we include monopole's Coulomb repulsion, and formulate a relation
between the mass, density and coupling which should be fulfilled at the
deconfinement point. We end up proposing various ways to test on the lattice
whether it is indeed the BEC point for monopoles.
\\ ( http://arxiv.org/abs/0906.2019 , 1465kb)
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arXiv:0906.2121
Date: Thu, 11 Jun 2009 15:16:07 GMT (2924kb)
Title: How to characterize the dynamics of cold atoms in non dissipative
optical lattices?
Authors: Daniel Hennequin (PhLAM), Philippe Verkerk (PhLAM)
Categories: physics.atom-ph
\\
We examine here the classical dynamics of cold atoms in square optical
lattices, i.e. lattices obtained with two orthogonal stationary plane waves.
Contrary to much of the past studies in this domain, the potential is here time
independent and non dissipative. We show that, as a function of the
experimental parameters, a very different behavior is obtained, both for the
dynamics of atoms trapped inside individual sites, and for atoms travelling
between sites: inside the sites, chaos may be a main regime or, on the
contrary, may be negligible; outside the sites, chaos sometimes coexists with
other regimes. We discuss what are the consequences of these differences on the
macroscopic behavior of the atoms in the lattice, and we propose experimental
measurements able to characterize these dynamics and to distinguish between the
different cases.
\\ ( http://arxiv.org/abs/0906.2121 , 2924kb)
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arXiv:0904.1160
replaced with revised version Mon, 8 Jun 2009 17:16:30 GMT (514kb)
Title: Spin dynamics and structure formation in a spin-1 condensate in a
magnetic field
Authors: Jordi Mur-Petit (UCL)
Categories: cond-mat.quant-gas quant-ph
Comments: 8 pages, 5 figures. Matches published version
Journal-ref: Physical Review A 79, 063603 (2009)
DOI: 10.1103/PhysRevA.79.063603
\\ ( http://arxiv.org/abs/0904.1160 , 514kb)
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arXiv:0904.3911
replaced with revised version Tue, 9 Jun 2009 16:19:19 GMT (266kb)
Title: Quantum linear Boltzmann equation
Authors: Bassano Vacchini, Klaus Hornberger
Categories: quant-ph math-ph math.MP
Comments: 63 pages, 6 figures; v2:minor corrections&updates, to appear in
Physics Reports
\\ ( http://arxiv.org/abs/0904.3911 , 266kb)
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arXiv:0905.1492
replaced with revised version Wed, 10 Jun 2009 17:42:07 GMT (210kb)
Title: Analytic description of atomic interaction at ultracold temperatures:
the case of a single channel
Authors: Bo Gao
Categories: physics.atom-ph physics.chem-ph
Comments: 12 pages, 4 figures, minor corrections, to be published in PRA
\\ ( http://arxiv.org/abs/0905.1492 , 210kb)
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arXiv:0901.1415
replaced with revised version Thu, 11 Jun 2009 08:05:02 GMT (337kb)
Title: Unconventional Bose-Einstein Condensations Beyond the "No-node" Theorem
Authors: Congjun Wu
Categories: cond-mat.supr-con cond-mat.str-el
Journal-ref: Mod. Phys. Lett. B 23, 1 (2009)
DOI: 10.1142/S0217984909017777
\\ ( http://arxiv.org/abs/0901.1415 , 337kb)
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arXiv:0904.2564
replaced with revised version Thu, 11 Jun 2009 13:46:54 GMT (563kb)
Title: Emergence of turbulence in an oscillating Bose-Einstein condensate
Authors: E.A.L. Henn, J.A.Seman, G.Roati, K.M.F. Magalhaes and V.S. Bagnato
Categories: cond-mat.quant-gas cond-mat.mes-hall
Comments: accepted for Phys. Rev. Lett
\\ ( http://arxiv.org/abs/0904.2564 , 563kb)
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Till next time,
Matt.
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Australia. www.physics.uq.edu.au/people/mdavis/
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