Matt's arXiv selection: week ending 7 March 2008.

From: Matthew Davis <>
Date: Tue, 18 Mar 2008 08:31:41 +1000

The following message was sent to the matts_arxiv list by Matthew Davis <>

Hi everyone,

A massive 36 new preprints and 15 replacements this week (well actually a couple
of weeks ago). You guys have been busy.

Date: Fri, 29 Feb 2008 00:20:01 GMT (535kb,D)

Title: Macroscopic superposition states in rotating ring lattices
Authors: Ana Maria Rey and Andreas Nunnenkamp
Categories: cond-mat.other
Comments: 8 pages, 4 figures; submitted to the PQE-2008 conference proceedings
   We investigate the effects of rotation on one-dimensional ultracold bosons
confined to optical ring lattices. First, we consider a uniform lattice and
show that there exists a critical rotation frequency at which the ground state
of a weakly-interacting and integer-filled atomic gas is fragmented into a
macroscopic superposition of two states with different circulation. Second, we
point out several advantages of slightly non-uniform ring lattices for the
generation of such kind of states. Finally, we demonstrate that different
quasi-momentum states can be distinguished in time-of-flight absorption imaging
and propose to probe correlations via the many-body oscillations induced by a
sudden change in the rotation frequency.
\\ ( , 535kb)
Date: Fri, 29 Feb 2008 04:31:25 GMT (240kb)

Title: Bright solitary waves of atomic Bose-Einstein condensates under rotation
Authors: N.A. Jamaludin, N.G. Parker and A.M. Martin
Categories: cond-mat.other
Comments: 4 pages, 3 figures
   We analyse the rotation of bright solitary waves formed of atomic
Bose-Einstein condensates with attractive atomic interactions. By employing a
variational technique and assuming an irrotational quadrupolar flow field, we
map out the variational solutions in the rotating frame. In particular, we show
that rotation has a considerable stabilising effect on the system,
significantly raising the critical threshold for collapse of the bright
solitary waves.
\\ ( , 240kb)
Date: Fri, 29 Feb 2008 11:39:46 GMT (205kb)

Title: Anisotropic scattering of Bogoliubov excitations
Authors: Christopher Gaul and Cord Axel M\"uller
Categories: cond-mat.other
Comments: 5 pages, 5 figures
   We investigate the interplay of disorder and interaction in 2D Bose-Einstein
condensates by studying the scattering of Bogoliubov excitations on spatial
fluctuations of an external optical potential. A numerical integration of the
Gross-Pitaevskii equation shows that the single-scattering amplitude has a
marked angular anisotropy. By a saddle-point expansion of the hydrodynamic
mean-field energy functional, we derive the relevant scattering amplitude
including the crossover from sound-like to particle-like excitations. The very
different scattering properties of these limiting cases are smoothly connected
by an angular envelope function with a well-defined node of vanishing
scattering amplitude. We find that the overall scattering is most efficient at
the crossover from phonon-like to particle-like Bogoliubov excitations.
\\ ( , 205kb)
Date: Fri, 29 Feb 2008 17:57:59 GMT (926kb)

Title: Imbalanced d-wave superfluids in the BCS-BEC crossover regime at finite
Authors: J. Tempere, S.N. Klimin, J.T. Devreese, V.V. Moshchalkov
Categories: cond-mat.supr-con
Comments: 22 pages, 7 figures
   Singlet pairing in a Fermi superfluid is frustrated when the amounts of
fermions of each pairing partner are unequal. The resulting `imbalanced
superfluid' has been realized experimentally for ultracold atomic gases with
s-wave interactions. Inspired by high-temperature superconductivity, we
investigate the case of d-wave interactions, and find marked differences from
the s-wave superfluid. Whereas s-wave imbalanced Fermi gases tend to phase
separate in real space, in a balanced condensate and an imbalanced normal halo,
we show that the d-wave gas can phase separate in reciprocal space so that
imbalance and superfluidity can coexist spatially. We show that the mechanism
explaining this property is the creation of polarized excitations in the nodes
of the gap. The Sarma mechanism, present only at nonzero temperatures for the
s-wave case, is still applicable in the temperature zero limit for the d-wave
case. As a result, the d-wave BCS superfluid is more robust with respect to
imbalance, and a region of the phase diagram can be identified where the s-wave
BCS superfluidity is suppressed whereas the d-wave superfluidity is not. When
these results are extended into the BEC limit of strongly bound molecules, the
symmetry of the order parameter matters less. The effects of fluctuations
beyond mean field is taken into account in the calculation of the structure
factor and the critical temperature. The poles of the structure factor
(corresponding to bound molecular states) are less damped in the d-wave case as
compared to s-wave. On the BCS side of the unitarity limit, the critical
temperature follows the temperature corresponding to the pair binding energy
and as such will also be more robust against imbalance. Possible routes for the
experimental observation of the d-wave superfluidity have been discussed.
\\ ( , 926kb)
arXiv:0802.4276 (*cross-listing*)
Date: Thu, 28 Feb 2008 20:14:54 GMT (68kb)

Title: Fermion- and Spin-Counting in Strongly Correlated Systems
Authors: Sibylle Braungardt, Aditi Sen De, Ujjwal Sen, Roy J. Glauber, Maciej
Categories: quant-ph cond-mat.stat-mech cond-mat.str-el
Comments: 8 pages, 7 figures, RevTeX4
   We apply the atom counting theory to strongly correlated Fermi systems and
spin models, which can be realized with ultracold atoms. The counting
distributions are typically sub-Poissonian and remain smooth at quantum phase
transitions, but their moments exhibit critical behavior, and characterize
quantum statistical properties of the system. Moreover, more detailed
characterizations are obtained with experimentally feasible spatially resolved
counting distributions.
\\ ( , 68kb)
Date: Fri, 29 Feb 2008 01:13:16 GMT (468kb)

Title: Identifying phases of matter that are universal for quantum computation
Authors: Andrew C. Doherty and Stephen D. Bartlett
Categories: quant-ph
Comments: 5 pages, 2 figures, comments welcome
   A recent breakthrough in quantum computing has been the realization that
quantum computation can proceed solely through single-qubit measurements on an
appropriate quantum state - for example, the ground state of an interacting
many-body system. It would be unfortunate, however, if the usefulness of a
ground state for quantum computation was critically dependent on the details of
the system's Hamiltonian; a much more powerful result would be the existence of
a robust ordered phase which is characterized by the ability to perform
measurement-based quantum computation (MBQC). To identify such phases, we
propose to use nonlocal correlation functions that quantify the fidelity of
quantum gates performed between distant qubits. We investigate a simple
spin-lattice system based on the cluster-state model for MBQC, and demonstrate
that it possesses a zero temperature phase transition between a disordered
phase and an ordered "cluster phase" in which it is possible to perform a
universal set of quantum gates.
\\ ( , 468kb)
Date: Fri, 29 Feb 2008 10:51:18 GMT (657kb)

Title: Multi-Cell Traps for Registering of Cold Atom Clouds
Authors: G.A. Kouzaev and K.J. Sand
Categories: quant-ph
Comments: 6 pages, 6 figures
   In this letter, the results on the development and simulation of new
three-dimensional nanotraps for cold dressed atoms are considered. The traps
are the multi-cell structures built by crossed non-touching carbon nanotubes.
The trapping effect is tuned by the DC and RF currents to confine the strong-
or low-potential seeking atoms far enough from the areas of strong
Casimir-Polder and spin-flip forces. It is supposed that the developed and
simulated multi-cell structures are pertinent for catching the Bose-Einstein
condensates to demonstrate the Josephson effect, and to enable the study of the
entanglement of confined clouds in three-dimensional nano-cells.
\\ ( , 657kb)
Date: Fri, 29 Feb 2008 15:50:02 GMT (703kb)

Title: Quantum reflection of bright matter-wave solitons
Authors: S. L. Cornish, N. G. Parker, A. M. Martin, T. E. Judd, R. G. Scott, T.
   M. Fromhold and C. S. Adams
Categories: quant-ph
Comments: 10 pages, 6 figures. Submitted to special issue of Physica D on
   "Nonlinear dynamics in degenerate quantum gases"
   We propose the use of bright matter-wave solitons formed from Bose-Einstein
condensates with attractive interactions to probe and study quantum reflection
from a solid surface at normal incidence. We demonstrate that the presence of
attractive interatomic interactions leads to a number of advantages for the
study of quantum reflection. The absence of dispersion as the soliton
propagates allows precise control of the velocity normal to the surface and for
much lower velocities to be achieved. Numerical modelling shows that the
robust, self-trapped nature of bright solitons leads to a clean reflection from
the surface, limiting the disruption of the density profile and permitting
accurate measurements of the reflection probability.
\\ ( , 703kb)
Date: Fri, 29 Feb 2008 14:46:16 GMT (459kb,D)

Title: Holographic quantum computing
Authors: Karl Tordrup, Antonio Negretti, and Klaus Molmer
Categories: quant-ph
Comments: 4 pages, 3 figures
   We propose that a single mesoscopic ensemble of trapped polar molecules can
support a "holographic quantum computer" with hundreds of qubits encoded in
collective excitations with definite spatial phase variations. Each phase
pattern is uniquely addressed by optical Raman processes with classical optical
fields, while one- and two-qubit gates are accomplished by selectively
transferring the individual qubit states to a stripline microwave cavity field
and a Cooper pair box where controllable two-level unitary dynamics is governed
by classical microwave fields.
\\ ( , 459kb)
Date: Mon, 3 Mar 2008 13:38:21 GMT (21kb)

Title: Resonant spin-changing collisions in spinor Fermi gases
Authors: N. Bornemann, P. Hyllus and L. Santos
Categories: cond-mat.other
Comments: 4 pages, 3 eps figures
   Spin-changing collisions in trapped Fermi gases may acquire a resonant
character due to the compensation of quadratic Zeeman effect and trap energy.
These resonances are absent in spinor condensates and pseudo-spin-1/2 Fermi
gases, being a characteristic feature of high-spin Fermi gases that allows
spinor physics at large magnetic fields. We analyze these resonances in detail
for the case of lattice spinor fermions, showing that they permit to
selectively target a spin-changing channel while suppressing all others. These
resonances allow for the controlled creation of non-trivial quantum
superpositions of many-particle states with entangled spin and trap degrees of
freedom, which remarkably are magnetic-field insensitive. Finally, we show that
the intersite tunneling may lead to a quantum phase transition described by an
effective quantum Ising model.
\\ ( , 21kb)
Date: Mon, 3 Mar 2008 14:08:04 GMT (134kb)

Title: Quantum Phase Analysis of Extended Bose-Hubbard Model
Authors: Manoranjan Kumar, Sujit Sarkar, S. Ramasesha
Categories: cond-mat.supr-con cond-mat.str-el
Comments: 4 pages, 5 figures
   We have obtained the quantum phase diagram of one dimensional extended
Bose-Hubbard model using the density-matrix renormalization group and Abelian
bosonization methods for different commensurabilities. We describe the nature
of different quantum phases at the charge degeneracy point. We find a direct
phase transition from Mott insulating phase to superconducting phase for
integer band fillings of bosons. We predict explicitly the presence of two
kinds of repulsive Luttinger liquid phases, apart from the charge density wave
and superconducting phases for half-integer band fillings. Our study reveals
that extended range interactions are necessary to get the correct phase
boundary of an one-dimensional interacting bosons system.
\\ ( , 134kb)
Date: Sat, 1 Mar 2008 11:13:43 GMT (454kb)

Title: Probing Mott lobes via the AC Josephson effect
Authors: M.X. Huo, Ying Li, Z. Song and C.P. Sun
Categories: quant-ph
Comments: 5 pages, 4 figures
   The alternating-current (AC) Josephson effect is studied in a system
consisting of two weakly coupled Bose Hubbard models. In the framework of the
mean field theory, Gross-Pitaevskii equations show that the amplitude of the
Josephson current is proportional to the product of superfluid order
parameters. In addition, the chemical potential--current relation for a small
size system is obtained via the exact numerical computation. This allows us to
propose a feasible experimental scheme to measure the Mott lobes of the quantum
phase transition.
\\ ( , 454kb)
Date: Sun, 2 Mar 2008 09:27:33 GMT (484kb,D)

Title: A novel scheme for entanglement engineering in a fermionic system
Authors: Jiming Gao, Jiaxiang Wang
Categories: quant-ph
   We present a novel scheme to engineer the entanglement in a fermionic system,
which is modeled by a minimally three-site Hubbard model. It is found that, in
this type of system, we can have two free parameters. One is used to tune the
entanglement and the other to switch on or off the above tuning function. The
whole process is much like what happens in a traditional transistor switch,
where the main current between the emitter and collector can be turned on or
off by the base current.
\\ ( , 484kb)
Date: Sun, 2 Mar 2008 23:35:35 GMT (92kb)

Title: Sub-Shot-Noise Quantum Optical Interferometry: A Comparison of Entangled
   State Performance within a Unified Measurement Scheme
Authors: Yang Gao and Hwang Lee
Categories: quant-ph
Comments: 5 pages, 2 figures
   Phase measurement using a lossless Mach-Zehnder interferometer with certain
entangled $N$-photon states can lead to a phase sensitivity of the order of
1/N, the Heisenberg limit. However, previously considered output measurement
schemes are different for different input states to achieve this limit. We show
that it is possible to achieve this limit just by the parity measurement for
all the commonly proposed entangled states. Based on the parity measurement
scheme, the reductions of the phase sensitivity in the presence of photon loss
are examined for the various input states.
\\ ( , 92kb)
Date: Mon, 3 Mar 2008 20:02:00 GMT (318kb)

Title: Optimal control of atom transport for quantum gates in optical lattices
Authors: G. De Chiara, T. Calarco, M. Anderlini, S. Montangero, P. J. Lee, B.
   L. Brown, W. D. Phillips, and J. V. Porto
Categories: quant-ph
   By means of optimal control techniques we model and optimize the manipulation
of the external quantum state (center-of-mass motion) of atoms trapped in
adjustable optical potentials. We consider in detail the cases of both non
interacting and interacting atoms moving between neighboring sites in a lattice
of a double-well optical potentials. Such a lattice can perform
interaction-mediated entanglement of atom pairs and can realize two-qubit
quantum gates. The optimized control sequences for the optical potential allow
transport faster and with significantly larger fidelity than is possible with
processes based on adiabatic transport.
\\ ( , 318kb)
Date: Mon, 3 Mar 2008 12:55:46 GMT (246kb)

Title: F-resolved Magneto-optical Resonances at D1 Excitation of Cesium:
   Experiment and Theory
Authors: Marcis Auzinsh, Ruvin Ferber, Florian Gahbauer, Andrey Jarmola, and
   Linards Kalvans
Categories: physics.atom-ph
Comments: 9 pages, 6 figures
   Bright and dark nonlinear magneto-optical resonances associated with the
ground state Hanle effect have been studied experimentally and theoretically
for D1 excitation of atomic cesium. This system offers the advantage that the
separation between the different hyperfine levels exceeds the Doppler width,
and, hence, transitions between individual levels can be studied separately.
Experimental measurements for various laser power densities and transit
relaxation times are compared with a model based on the optical Bloch
equations, which averages over the Doppler contour of the absorption line and
simultaneously takes into account all hyperfine levels, as well as mixing of
magnetic sublevels in an external magnetic field. In contrast to previous
studies, which could not resolve the hyperfine transitions because of Doppler
broadening, in this study there is excellent agreement between experiment and
theory regarding the sign (bright or dark), contrast, and width of the
resonance. The results support the traditional theoretical interpretation,
according to which these effects are related to the relative strengths of
transition probabilities between different magnetic sublevels in a given
hyperfine transition.
\\ ( , 246kb)
Date: Mon, 3 Mar 2008 22:46:45 GMT (467kb)

Title: Dynamical Creation of Fractionalized Vortices and Vortex Lattices
Authors: An-Chun Ji, W. M. Liu (CAS), Jun Liang Song and Fei Zhou (UBC)
Categories: cond-mat.other cond-mat.dis-nn
Comments: 5 pages, 3 figures
   We investigate dynamic creation of fractionalized half-quantum vortices in
Bose-Einstein condensates of sodium atoms. Our simulations show that both
individual half-quantum vortices and vortex lattices can be created in rotating
optical traps when additional pulsed magnetic trapping potentials are applied.
We also find that a distinct periodically modulated spin-density-wave spatial
structure is always embedded in square half-quantum vortex lattices; this
structure can be conveniently probed by taking absorption images of
ballistically expanding cold atoms in a Stern-Gerlach field.
\\ ( , 467kb)
Date: Tue, 4 Mar 2008 18:17:59 GMT (593kb,D)

Title: Numerical observation of Hawking radiation from acoustic black holes in
   atomic BECs
Authors: Iacopo Carusotto, Serena Fagnocchi, Alessio Recati, Roberto Balbinot,
   Alessandro Fabbri
Categories: cond-mat.other gr-qc
   We report numerical evidence of Hawking emission of Bogoliubov phonons from a
sonic horizon in a flowing one-dimensional atomic Bose-Einstein condensate. The
presence of Hawking radiation is revealed from peculiar long-range patterns in
the density-density correlation function of the gas. Quantitative agreement
between our fully microscopic calculations and the prediction of analog models
is obtained in the hydrodynamic limit. New features are predicted and the
effect of a finite initial temperature discussed.
\\ ( , 593kb)
Date: Tue, 4 Mar 2008 21:01:25 GMT (158kb)

Title: Influence of the trap shape on the superfluid-Mott transition in
   ultracold atomic gases
Authors: Ping Nang Ma, Kai Yu Yang, Lode Pollet, J. V. Porto, Matthias Troyer,
   Fu Chun Zhang
Categories: cond-mat.other cond-mat.stat-mech
Comments: 5 pages, 6 figures
   The coexistence of superfluid and Mott insulator, due to the quadratic
confinement potential in current optical lattice experiments, makes the
accurate detection of the superfluid-Mott transition difficult. Studying
alternative trapping potentials which are experimentally realizable and have a
flatter center, we find that the transition can be better resolved, but at the
cost of a more difficult tuning of the particle filling. When mapping out the
phase diagram using local probes and the local density approximation we find
that the smoother gradient of the parabolic trap is advantageous.
\\ ( , 158kb)
Date: Tue, 4 Mar 2008 22:08:15 GMT (511kb)

Title: Simulation of an inhomogeneous Fermi gas through the BCS-BEC crossover
Authors: R. Jauregui, R. Paredes, L. Rosales-Zarate, and G. Toledo Sanchez
Categories: cond-mat.other
Comments: 14 pages,8 figures
   We perform a variational quantum Monte Carlo simulation of the transition
from a Bose-Einstein condensate (BEC) to a Bardeen-Cooper-Schrieffer superfluid
(BCS) at zero temperature. The model Hamiltonian involves an attractive short
range two body interaction and the atoms number $2N =330$ is chosen so that, in
the non-interacting limit, the ground state function corresponds to a closed
shell configuration. The system is then characterized by the $s$-wave
scattering length $a$ of the two-particle collisions in the gas, which is
varied from negative to positive values, and the Fermi wave number $k_F$. Based
on an exhaustive analysis of the two-body problem, one parameter variational
many-body wave functions are proposed to describe the ground state of the
interacting Fermi gas from BCS to BEC states. We exploit properties of
antisymmetrized many-body functions to develop efficient techniques that permit
variational calculations for a large number of particles. It is shown that a
virial relation between the energy per particle and the trapping energy is
approximately valid for $-0.1<1/k_Fa<1.4$. The influence of the harmonic trap
and the interaction potential as exhibited in two-body correlation functions is
also analyzed.
\\ ( , 511kb)
Date: Wed, 5 Mar 2008 13:13:23 GMT (120kb)

Title: Accurate near-threshold model for ultracold KRb dimers from interisotope
   Feshbach spectroscopy
Authors: A. Simoni, M. Zaccanti, C. D'Errico, M. Fattori, G. Roati, M.
   Inguscio, G. Modugno
Categories: cond-mat.other
Comments: 9 pages, 7 figures
   We investigate magnetic Feshbach resonances in two different ultracold K-Rb
mixtures. Information on the K(39)-Rb(87) isotopic pair is combined with novel
and pre-existing observations of resonance patterns for K(40)-Rb(87).
Interisotope resonance spectroscopy improves significantly our near-threshold
model for scattering and bound-state calculations. Our analysis determines the
number of bound states in singlet/triplet potentials and establishes precisely
near threshold parameters for all K-Rb pairs of interest for experiments with
both atoms and molecules. In addition, the model verifies the validity of the
Born-Oppenheimer approximation at the present level of accuracy.
\\ ( , 120kb)
Date: Wed, 5 Mar 2008 16:16:43 GMT (112kb)

Title: Real space Bogolubov-de Gennes equations study of the boson-fermion
Authors: Jaromir Krzyszczak, Tadeusz Doma\'nski, Karol I. Wysoki\'nski
Categories: cond-mat.supr-con
Comments: 5 pages with 5 Postscript figures, presented at 13 Krajowa Szkola
   Nadprzewodnictwa (Ladek-Zdroj 2007), will be published in APP-A, uses
   The boson-fermion (BF) model has been proposed to describe superconductivity
in short coherence length superconductors. In this work we use it to study
impurity induced inhomogeneities in high temperature superconductors (HTS) as
found in numerous scanning tunnelling measurements. The model has been
formulated in real space and solved with help of Bogolubov-de Gennes approach.
Disorder in the boson or fermion subsystem is directly coupled to the
superconducting order parameter and leads to severe changes of superconducting
properties like local order parameter and density of states. We present the
results for many impurities randomly distributed over otherwise clean and
periodic two-dimensional square lattice.
\\ ( , 112kb)
Date: Wed, 5 Mar 2008 19:14:52 GMT (139kb)

Title: Theoretical Investigation of Fermion Pairings in Three-band Extended
   Hubbard Model
Authors: Partha Goswami
Categories: cond-mat.supr-con cond-mat.str-el
Comments: 22pages,No figures
   The two-dimensional d-p model (or extended Hubbard model) on a square lattice
is investigated for fermion pairing by a slave boson method. The inter-site
d-fermion interaction is introduced additionally. The momentum space
counterpart of this interaction is taken to be separable and expanded in terms
of basis functions corresponding to mixed symmetry states. The investigation
leads to anomalous pairing of fermion fields only for pure d-wave symmetry. The
charge and spin ordering gaps appear in the single- particle spectrum when
d(x,y) state is taken into account.The non-Fermi liquid behavior is found to be
the prevalent one generally. The study yields a good qualitative account of the
nodal-antinodal dichotomy. Two gaps appear in the normal state spectrum; the
larger one corresponds to the sum and the smaller to the difference of spin and
charge ordering gaps. This two-gap scenario is in qualitative agreement with
recent experimental finding.
\\ ( , 139kb)
arXiv:0803.0282 (*cross-listing*)
Date: Mon, 3 Mar 2008 16:51:51 GMT (167kb)

Title: On a new definition of quantum entropy
Authors: Michele Campisi
Categories: quant-ph cond-mat.stat-mech
Comments: 4 pages, 3 figures
   It is proved here that, as a consequence of the unitary quantum evolution,
the expectation value of a properly defined quantum entropy operator (as
opposed to the non-evolving von Neumann entropy) can only increase during non
adiabatic transformations and remains constant during adiabatic ones. Thus
Clausius formulation of the second law is established as a theorem in quantum
mechanics, in a way that is equivalent to the previously established
formulation in terms of minimal work principle [A. E. Allahverdyan and T. M.
Nieuwenhuizen, Phys. Rev. E 71, 046107 (2005)]. The corresponding Quantum
Mechanical Principle of Entropy Increase is then illustrated with an exactly
solvable example, namely the driven harmonic oscillator. Attention is paid to
both microcanonical and canonical initial condition. The results are compared
to their classical counterparts.
\\ ( , 167kb)
Date: Wed, 5 Mar 2008 10:02:53 GMT (519kb)

Title: Quantum dynamics of one and two bosonic atoms in a combined
   tight-binding periodic and weak parabolic potential
Authors: Manuel Valiente and David Petrosyan
Categories: quant-ph
Comments: 6 pages, 6 figures
   Strongly interacting bosonic particles in a tight-binding periodic potential
superimposed by a weak parabolic trap is a paradigm for many cold atom
experiments. Here, after revisiting the single particle problem, we study
interaction-bound dimers of bosonic atoms in the combined lattice and parabolic
potential. We consider both repulsively- and attractively-bound dimers and find
pronounced differences in their behaviour. We identify conditions under which
attractive and repulsive dimers exhibit analogous dynamics. Our studies reveal
that coherent transport and periodic oscillations of appropriately prepared
one- and two-atom wavepackets can be achieved, which may facilitate information
transfer in optical lattice based quantum computation schemes.
\\ ( , 519kb)
Date: Wed, 5 Mar 2008 13:01:29 GMT (859kb,D)

Title: Alternating gradient focusing and deceleration of large molecules
Authors: Kirstin Wohlfart, Fabian Gr\"atz, Frank Filsinger, Henrik Haak, Gerard
   Meijer, and Jochen K\"upper
Categories: physics.atom-ph physics.acc-ph physics.chem-ph
Comments: 5 pages, 4 figures, revtex4
   We have focused and decelerated benzonitrile (C$_7$H$_5$N) molecules from a
molecular beam, using an array of time-varying inhomogeneous electric fields in
alternating gradient configuration. Benzonitrile is prototypical for large
asymmetric top molecules that exhibit rich rotational structure and a high
density of states. At the rotational temperature of 3.5 K in the pulsed
molecular beam, many rotational states are populated. Benzonitrile molecules in
their absolute ground state are decelerated from 320 m/s to 289 m/s, and
similar changes in velocity are obtained for excited rotational states. All
measurements agree well with the outcome of trajectory calculations. These
experiments demonstrate that such large polyatomic molecules are amenable to
the powerful method of Stark deceleration.
\\ ( , 859kb)
Date: Thu, 6 Mar 2008 11:55:55 GMT (5kb)

Title: Generalized Virial Theorem and Pressure Relation for a strongly
   correlated Fermi gas
Authors: Shina Tan
Categories: cond-mat.stat-mech
Comments: 5 pages
   For a two-component Fermi gas in the unitarity limit (ie, with infinite
scattering length), there is a well-known virial theorem, first shown by J. E.
Thomas et al, Phys. Rev. Lett. 95, 120402 (2005). A few people rederived this
result, and extended it to few-body systems, but their results are all
restricted to the unitarity limit. Here I show that there is a generalized
virial theorem for FINITE scattering lengths. I also generalize an exact result
concerning the pressure, first shown in cond-mat/0508320, to the case of
imbalanced populations.
\\ ( , 5kb)
Date: Thu, 6 Mar 2008 12:33:03 GMT (520kb)

Title: Ground State Properties of a Tonks-Girardeau Gas in a Split Trap
Authors: J. Goold and Th. Busch
Categories: cond-mat.other
Comments: 7 pages, 9 figures
   We determine the exact many-body properties of a bosonic Tonks-Girardeau gas
confined in a harmonic potential with a tunable $\delta$-function barrier at
the trap center. This is done by calculating the reduced single particle
density matrix, the pair-distribution function, and momentum distribution of
the gas as a function of barrier strength and particle number. With increasing
barrier height we find that the ground state occupation in a diagonal basis
diverges from the $\sqrt N$ behavior that is expected for the case of a simple
harmonic trap. In fact, the scaling of the occupation number depends on whether
one has an even or odd number of particles. Since this quantity is a measure of
the coherence of our sample we show how the odd-even effect manifests itself in
both the momentum distribution of the Bose gas and interference fringe
visibility during free temporal evolution.
\\ ( , 520kb)
Date: Thu, 6 Mar 2008 15:10:05 GMT (16kb)

Title: Condensation of Classical Nonlinear Waves in a Two-Component System
Authors: Hayder Salman and Natalia G. Berloff
Categories: cond-mat.stat-mech cond-mat.soft
Comments: 4 pages, 1 figure
   We study the formation of large-scale coherent structures (a condensate) for
a system of two weakly interacting classical waves. Using the coupled
defocusing nonlinear Schr\"odinger (NLS) equations as a representative model,
we focus on condensation in the phase mixing regime. We employ weak turbulence
theory to provide a complete thermodynamic description of the classical
condensation process. We show that the temperature and the condensate mass
fractions are fully determined by the total number of particles in each
component and the initial total energy. Moreover, we find that, at higher
energies, condensation can occur in only one component. The theory presented
provides excellent agreement with results of numerical simulations obtained by
directly integrating the dynamical model.
\\ ( , 16kb)
Date: Wed, 5 Mar 2008 23:33:29 GMT (306kb,D)

Title: Phase transitions, entanglement and quantum noise interferometry in cold
Authors: Florian Mintert, Ana Maria Rey, Indubala I. Satija, Charles W. Clark
Categories: quant-ph
Comments: 4 pages 4 figures
   We show that entanglement monotones can characterize the pronounced
enhancement of entanglement at a quantum phase transition if they are sensitive
to long-range high order correlations. These monotones are found to develop a
sharp peak at the critical point and to exhibit universal scaling. We
demonstrate that similar features are shared by noise correlations and verify
that these experimentally accessible quantities indeed encode entanglement
information and probe separability.
\\ ( , 306kb)
Date: Thu, 6 Mar 2008 00:18:44 GMT (117kb)

Title: Entanglement in a hardcore-boson Hubbard model
Authors: Xiang Hao, Shiqun Zhu
Categories: quant-ph
Comments: 10 pages, 3 figures
   The entanglement in a Hubbard chain of hardcore bosons is investigated. The
analytic expression of the global entanglement in ground state is derived. The
divergence of the derivative of the global entanglement shows the quantum
criticality of the ground state. For the thermal equilibrium state, the
bipartite and the multipartite entanglement are evaluated. The entanglement
decreases to zero at a certain temperature. The thermal entanglement is rapidly
decreasing with the increase of the number of sites in the lattice. The
bipartite thermal entanglement approaches a constant value at a certain number
of sites while the multipartite entanglement eventually vanishes.
\\ ( , 117kb)
Date: Thu, 6 Mar 2008 04:56:45 GMT (19kb)

Title: Stimulated Raman adiabatic passage in a multi-level atom
Authors: A. D. Boozer
Categories: quant-ph
Comments: 14 pages, 2 figures
Journal-ref: Phys. Rev. A 77, 023411 (2008)
   We present a general formalism for describing stimulated Raman adiabatic
passage in a multi-level atom. The atom is assumed to have two ground state
manifolds a and b and an excited state manifold e, and the adiabatic passage is
carried out by resonantly driving the a-e and b-e transitions with
time-dependent fields. Our formalism gives a complete description of the
adiabatic passage process, and can be applied to systems with arbitrary numbers
of degenerate states in each manifold and arbitrary couplings of the a-e and
b-e transitions. We illustrate the formalism by applying it to both a simple
toy model and to adiabatic passage in the Cesium atom.
\\ ( , 19kb)
Date: Thu, 6 Mar 2008 15:29:45 GMT (342kb)

Title: Locality of dynamics in general harmonic quantum systems
Authors: M. Cramer, A. Serafini, J. Eisert
Categories: quant-ph
Comments: 19 pages latex, contribution to proceedings of "Quantum Information
   and Many-Body Quantum Systems" Workshop, 26-31 Mar 2007, Pisa
   The Lieb-Robinson theorem states that locality is approximately preserved in
the dynamics of quantum lattice systems. Whenever one has finite-dimensional
constituents, observables evolving in time under a local Hamiltonian will
essentially grow linearly in their support, up to exponentially suppressed
corrections. In this work, we formulate Lieb-Robinson bounds for general
harmonic systems on general lattices, for which the constituents are
infinite-dimensional, as systems representing discrete versions of free fields
or the harmonic approximation to the Bose-Hubbard model. We consider both local
interactions as well as infinite-ranged interactions, showing how corrections
to locality are inherited from the locality of the Hamiltonian: Local
interactions result in stronger than exponentially suppressed corrections,
while non-local algebraic interactions result in algebraic suppression. We
derive bounds for canonical operators, Weyl operators and outline
generalization to arbitrary operators. As an example, we discuss the
Klein-Gordon field, and see how the approximate locality in the lattice model
becomes the exact causality in the field limit. We discuss the applicability of
these results to quenched lattice systems far from equilibrium, and the
dynamics of quantum phase transitions.
\\ ( , 342kb)
Date: Thu, 6 Mar 2008 04:48:16 GMT (254kb)

Title: Proposing for decelerating a cw filtering out molecular beam with a
   quasi-cw semi-Gaussian laser beam
Authors: Yaling Yin, Yong Xia, and Jianping Yin
Categories: physics.atom-ph
Comments: 14 pages, 4 figures
   We propose a promising scheme to decelerate a cw filtering out molecular beam
using a red-detuned quasi-cw semi-Gaussian laser beam. By using Monte-Carlo
simulation method, we demonstrate this optical Stark deceleration scheme, and
study its decelerated dynamic process for a cw ND3 molecular beam as well as
the dependence of the deceleration effect on the border width of the
semi-Gaussian beam. Our study shows that the proposed scheme can be used to
efficiently slow a cw ND3 molecular beam, and obtain a relative average
kinetic-energy loss of 9.33% by using a single semi-Gaussian beam with a well
depth of 7.3 mK.
\\ ( , 254kb)
Date: Thu, 6 Mar 2008 19:13:16 GMT (321kb)

Title: A Smooth, Inductively Coupled Ring Trap for Atoms
Authors: P. F. Griffin, E. Riis, and A. S. Arnold
Categories: physics.atom-ph
Comments: 4 pages, 5 figures
   We propose and numerically investigate a scalable ring trap for cold atoms
that surmounts problems of roughness of the potential and end--effects of trap
wires. A stable trapping potential is formed about an electrically isolated,
conducting loop in an ac magnetic field by time averaging the superposition of
the external and induced magnetic fields. We investigate the use of additional
fields to eliminate Majorana spin flip losses and to create novel trapping
geometries. The possibility of micro--fabrication of these ring traps offers
the prospect of developing Sagnac atom interferometry in atom--chip devices.
\\ ( , 321kb)
Date: Thu, 6 Mar 2008 20:26:41 GMT (991kb,D)

Title: Preparation and manipulation of molecules for fundamental physics tests
Authors: M.R. Tarbutt, J.J. Hudson, B.E. Sauer, and E.A. Hinds
Categories: physics.atom-ph
Comments: 22 pages, 18 figures
   This paper is a chapter from an upcoming book on cold molecule physics. In it
we describe techniques for the preparation and manipulation of cold molecules.
We further describe techniques for applying said cold molecules to tests of
fundamental physics.
\\ ( , 991kb)

The replacements:

replaced with revised version Fri, 29 Feb 2008 03:35:49 GMT (14kb)

Title: On the Hydrodynamic Boundary Condition for Superfluid Flow
Authors: Yves Pomeau and David C. Roberts
Categories: cond-mat.stat-mech cond-mat.other
Comments: Accepted to Phys. Rev. B. v2: greatly expanded discussion; clarified
   unclear areas and corrected misleading statements
\\ ( , 14kb)
replaced with revised version Fri, 29 Feb 2008 15:16:54 GMT (87kb)

Title: Functional renormalization for quantum phase transitions with
   non-relativistic bosons
Authors: C.Wetterich
Categories: cond-mat.supr-con astro-ph cond-mat.str-el hep-th
Comments: 31 pages, new references
\\ ( , 87kb)
replaced with revised version Fri, 29 Feb 2008 20:29:33 GMT (313kb)

Title: Metastable Feshbach Molecules in High Rotational States
Authors: S. Knoop, M. Mark, F. Ferlaino, J.G. Danzl, T. Kraemer, H.-C. Naegerl,
   R. Grimm
Categories: cond-mat.other
Comments: 4 pages, 5 figures
Journal-ref: Phys. Rev. Lett. 100, 083002 (2008)
DOI: 10.1103/PhysRevLett.100.083002
\\ ( , 313kb)
replaced with revised version Fri, 29 Feb 2008 17:40:44 GMT (534kb,D)

Title: Phase Coherence and Superfluid-Insulator Transition in a Disordered
   Bose-Einstein Condensate
Authors: Yong P. Chen, J. Hitchcock, D. Dries, M. Junker, C. Welford, R. G.
Categories: cond-mat.other
Comments: 4 pages, 5 figures, distortions in figures 1 and 4 have been fixed in
   version 3. This paper has been accepted to PRA
\\ ( , 534kb)
replaced with revised version Mon, 3 Mar 2008 06:04:56 GMT (24kb)

Title: Mixture of bosonic and spin-polarized fermionic atoms in an optical
Authors: Lode Pollet, Corinna Kollath, Ulrich Schollwoeck, Matthias Troyer
Categories: cond-mat.other cond-mat.stat-mech
Comments: 4 pages, 5 figures
Journal-ref: Phys. Rev. A 77, 023608 (2008)
DOI: 10.1103/PhysRevA.77.023608
\\ ( , 24kb)
replaced with revised version Mon, 3 Mar 2008 09:25:53 GMT (847kb)

Title: Probing quantum and thermal noise in an interacting many-body system
Authors: S. Hofferberth, I. Lesanovsky, T. Schumm, A. Imambekov, V. Gritsev, E.
   Demler, J. Schmiedmayer
Categories: cond-mat.other
\\ ( , 847kb)
replaced with revised version Fri, 29 Feb 2008 12:17:13 GMT (30kb)

Title: Nonlinear behavior of bosons in anisotropic optical lattices
Authors: A. Cetoli, E. Lundh
Categories: cond-mat.other
Comments: 5 pages, 4 figures, discussion revised after referee comments
\\ ( , 30kb)
replaced with revised version Mon, 3 Mar 2008 17:04:48 GMT (657kb,D)

Title: Creation, manipulation, and detection of anyons in optical lattices
Authors: M. Aguado, G. K. Brennen, F. Verstraete, J. I. Cirac
Categories: quant-ph cond-mat.other
Comments: 8 pages, 4 pdf figures; v2: reference added, typos fixed
\\ ( , 657kb)
replaced with revised version Tue, 4 Mar 2008 07:21:29 GMT (15kb)

Title: Finite Temperature Scaling Theory for the Collapse of BEC
Authors: Shyamal Biswas
Categories: cond-mat.stat-mech
Comments: 3 pages, 2 figures
\\ ( , 15kb)
replaced with revised version Tue, 4 Mar 2008 18:09:57 GMT (9kb)

Title: Supersymmetry and Goldstino Mode in Bose-Fermi Mixtures
Authors: Yue Yu and Kun Yang
Categories: cond-mat.other cond-mat.str-el
Comments: 4 pages. V2: published version
Journal-ref: Phys. Rev. Lett. 100, 090404 (2008)
DOI: 10.1103/PhysRevLett.100.090404
\\ ( , 9kb)
replaced with revised version Tue, 4 Mar 2008 11:17:37 GMT (110kb)

Title: Twin peaks in rf spectra of Fermi gases at unitarity
Authors: P. Massignan, G. M. Bruun and H. T. C. Stoof
Categories: cond-mat.other cond-mat.str-el
Comments: v3: version accepted for publication as a Rapid Communication in PRA.
   With respect to v2, minor changes in the text and in the inset of Fig. 2
Journal-ref: Phys. Rev. A 77, 031601(R) (2008)
DOI: 10.1103/PhysRevA.77.031601
\\ ( , 110kb)
replaced with revised version Tue, 4 Mar 2008 02:59:38 GMT (21kb)

Title: Correlation Functions of One-Dimensional Lieb-Liniger Anyons
Authors: Ovidiu I. Patu, Vladimir E. Korepin, Dmitri V. Averin
Categories: cond-mat.stat-mech quant-ph
Comments: 19 pages, RevTeX 4
Journal-ref: J. Phys. A: Math. Theor. 40 (2007) 14963-14984
\\ ( , 21kb)
replaced with revised version Wed, 5 Mar 2008 20:54:09 GMT (496kb)

Title: Two-body transients in coupled atomic-molecular BECs
Authors: Pascal Naidon, Eite Tiesinga and Paul S. Julienne
Categories: physics.atom-ph
Comments: 4 pages, 3 figures - typos corrected in formulae
\\ ( , 496kb)
replaced with revised version Thu, 6 Mar 2008 04:11:45 GMT (28kb)

Title: Energetics of a strongly correlated Fermi gas
Authors: Shina Tan
Categories: cond-mat.stat-mech
Comments: 28 pages, 1 figure
\\ ( , 28kb)
replaced with revised version Thu, 6 Mar 2008 07:24:18 GMT (201kb)

Title: Phase diagram of anisotropic boson t-J model
Authors: M. Boninsegni and N. V. Prokof'ev
Categories: cond-mat.stat-mech cond-mat.other
Comments: Replaced with published version
Journal-ref: Phys. Rev. B 77, 092502 (2008)
DOI: 10.1103/PhysRevB.77.092502
\\ ( , 201kb)

Till next time,

Dr M. J. Davis,               Senior Lecturer in Physics
School of Physical Sciences,  email:
University of Queensland,     ph   : +61 7 334 69824
Brisbane, QLD 4072,           fax  : +61 7 336 51242
Matt's arXiv selection: weekly summary of cold-atom papers from
Legal stuff: Unless stated otherwise, this e-mail represents only the
views of the sender and not the views of the University of Queensland
Received on Wed Apr 02 2008 - 09:39:35 EST

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