Matt's arXiv selection, Monday 6th February 2006.

From: Matthew Davis <>
Date: Fri, 3 Feb 2006 16:47:46 +1000 (EST)

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

This week's email is going out early. Remember to let your colleagues
know about this arXiv filtering service: they can sign up at

Have a good weekend,

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
Paper: cond-mat/0601628
Date: Fri, 27 Jan 2006 07:25:28 GMT   (21kb)
Title: Entanglement properties of degenerate four-wave mixing of matter-waves
   in a periodic potential
Authors: M.K. Olsen and M.J. Davis
Comments: 4 pages, 3 figures
Subj-class: Other
   In a recent experiment Campbell et al. [Phys. Rev. Lett. 96, 020406 (2006)]
observed degenerate four-wave mixing of matter-waves in a one-dimensional
optical lattice, a process with potential for generating entanglement among
atoms. We analyse the essential quantum features of the experiment to show that
entanglement is created between the quadratures of the two scattered atomic
clouds and is a true many-body (rather than two-body) effect. We demonstrate a
significant violation of entanglement inequalities that is robust to a moderate
level of coherent seeding. The system is thus a promising candididate for
generating macroscopically entangled atomic samples.
\\ ( ,  21kb)
Paper: cond-mat/0601633
Date: Fri, 27 Jan 2006 13:25:58 GMT   (644kb)
Title: Fabrication of magnetic atom chips based on FePt
Authors: Y. T. Xing, I. Barb, R. Gerritsma, R. J. C. Spreeuw, H. Luigjes, Q. F.
   Xiao, C. Retif, and J. B. Goedkoop
Comments: 5 pages, 5 figures
Subj-class: Materials Science
   We describe the design and fabrication of novel all-magnetic atom chips for
use in ultracold atom trapping. The considerations leading to the choice of
nanocrystalline exchange coupled FePt as best material are discussed. Using
stray field calculations, we designed patterns that function as magnetic atom
traps. These patterns were realized by spark erosion of FePt foil and e-beam
lithography of FePt film. A mirror magneto-optical trap (MMOT) was obtained
using the stray field of the foil chip.
\\ ( ,  644kb)
Paper: cond-mat/0412549
replaced with revised version Fri, 27 Jan 2006 11:14:22 GMT   (539kb)
Title: Emergence of superfluidity in a dynamical system of ultracold atoms
Authors: Joachim Brand and Andrey R. Kolovsky
Subj-class: Other
\\ ( ,  539kb)
Paper: quant-ph/0601180
Date: Fri, 27 Jan 2006 07:10:04 GMT   (437kb)
Title: Analysis of photon-atom entanglement generated by Faraday rotation in a
Authors: S. K. Y. Lee and C. K. Law
Comments: 6 pages, 3 figures
   Faraday rotation based on AC Stark shifts is a mechanism that can entangle
the polarization variables of photons and atoms. We analyze the structure of
such entanglement by using the Schmidt decomposition method. The
time-dependence of entanglement entropy and the effective Schmidt number are
derived for Gaussian amplitudes. In particular we show how the entanglement is
controlled by the initial fluctuations of atoms and photons.
\\ ( ,  437kb)
Paper: quant-ph/0601184
Date: Fri, 27 Jan 2006 10:46:49 GMT   (319kb)
Title: A deterministic cavity-QED source of polarization entangled photon pairs
Authors: R. Garcia-Maraver, K. Eckert, R. Corbalan, and J. Mompart
Comments: 5 pages, 5 figures
   We present two cavity quantum electrodynamics proposals that, sharing the
same basic elements, allow for the deterministic generation of entangled
photons pairs by means of a three-level atom successively coupled to two single
longitudinal mode high-Q optical resonators presenting polarization degeneracy.
In the faster proposal, the three-level atom yields a polarization entangled
photon pair via two truncated Rabi oscillations, whereas in the adiabatic
proposal a counterintuitive Stimulated Raman Adiabatic Passage process is
considered. Although slower than the former process, this second method is very
efficient and robust under fluctuations of the experimental parameters and,
particularly interesting, almost completely insensitive to atomic decay.
\\ ( ,  319kb)
Paper: quant-ph/0601186
Date: Fri, 27 Jan 2006 15:14:12 GMT   (572kb)
Title: Deterministic atom-light quantum interface
Authors: Jacob Sherson, Brian Julsgaard, and E. S. Polzik
Comments: 50 pages (bookstyle) 15 graphs, to be published in "Advances in
   Atomic, Molecular, and Optical Physics" Vol. 54. (2006)(Some of the graphs
   here have lower resolution than in the version to be published)
   The notion of an atom-light quantum interface has been developed in the past
decade, to a large extent due to demands within the new field of quantum
information processing and communication. A promising type of such interface
using large atomic ensembles has emerged in the past several years. In this
article we review this area of research with a special emphasis on
deterministic high fidelity quantum information protocols. Two recent
experiments, entanglement of distant atomic objects and quantum memory for
light are described in detail.
\\ ( ,  572kb)
Paper: quant-ph/0601187
Date: Fri, 27 Jan 2006 16:39:41 GMT   (136kb)
Title: Entangled photons on-demand from single quantum dots
Authors: Robert J. Young, R. Mark Stevenson, Paola Atkinson, Ken Cooper, David
   A. Ritchie, Andrew J. Shields
Comments: 9 pages
   We demonstrate the on-demand emission of polarisation-entangled photon pairs
from the biexciton cascade of a single InAs quantum dot embedded in a GaAs/AlAs
planar microcavity. Improvements in the sample design blue shifts the wetting
layer to reduce the contribution of background light in the measurements.
Results presented show that >70% of the detected photon pairs are entangled.
The high fidelity of the (|HxxHx>+|VxxVx>)/2^0.5 state that we determine is
sufficient to satisfy numerous tests for entanglement. The improved quality of
entanglement represents a significant step towards the realisation of a
practical quantum dot source compatible with applications in quantum
\\ ( ,  136kb)
Paper: physics/0512016
replaced with revised version Fri, 27 Jan 2006 20:26:14 GMT   (86kb)
Title: Direct Imaging of Periodic Sub-wavelength Patterns of Total Atomic
Authors: Alexei Tonyushkin and Tycho Sleator
Comments: 4 pages, 4 figures, to be submitted to Phys. Rev. A; order
   rearranged, references replaced and added, corrected typos
Subj-class: Atomic Physics; Optics
\\ ( ,  86kb)
Paper: cond-mat/0601650
Date: Sun, 29 Jan 2006 08:36:10 GMT   (36kb)
Title: Dynamics of the Bose-Hubbard model: from Mott insulator to superfluid
Authors: Fernando M. Cucchietti, Bodgan Damski, Jacek Dziarmaga, Wojciech H.
Comments: 4 pages & 3 figures
Report-no: LAUR-06-0477
Subj-class: Other
   We study dynamics of the one dimensional Bose-Hubbard model. To this aim we
change the tunneling frequency at a finite rate driving the system from Mott
insulator to superfluid regime. We describe build up of correlations during
such transitions using variational wave functions, dynamical BCS-Bogoliubov
theory, estimates based on the Kibble-Zurek mechanism, and numerical
simulations. We show that time-dependent correlations satisfy characteristic
scaling relations being directly experimentally measurable, e.g., in a
ring-shaped optical lattice filled with ultracold atoms.
\\ ( ,  36kb)
Paper: cond-mat/0601664
Date: Mon, 30 Jan 2006 13:53:46 GMT   (76kb)
Title: Formation of bright matter-wave solitons during the collapse of
   Bose-Einstein condensates
Authors: Simon L. Cornish, Sarah T. Thompson and Carl E. Wieman
Comments: 4 pages, 4 figures
Subj-class: Other
   We observe bright matter-wave solitons form during the collapse of 85Rb
condensates in a three-dimensional magnetic trap. The collapse is induced by
using a Feshbach resonance to suddenly switch the atomic interactions from
repulsive to attractive. Remnant condensates containing several times the
critical number of atoms for the onset of instability are observed to survive
the collapse. Under these conditions a highly robust configuration of solitons
forms such that each soliton satisfies the condition for stability and
neighboring solitons exhibit repulsive interactions.
\\ ( ,  76kb)
Paper: quant-ph/0601202
Date: Mon, 30 Jan 2006 17:07:11 GMT   (367kb)
Title: Probing BEC phase fluctuations with atomic quantum dots
Authors: M. Bruderer, D. Jaksch
Comments: 11 pages, 3 figures
   We consider the dephasing of two internal states |0> and |1> of a trapped
impurity atom, a so-called atomic quantum dot (AQD), where only state |1>
couples to a Bose-Einstein condensate (BEC). A direct relation between the
dephasing of the internal states of the AQD and the temporal phase fluctuations
of the BEC is established. Based on this relation we suggest a scheme to probe
BEC phase fluctuations nondestructively via dephasing measurements of the AQD.
In particular, the scheme allows to trace the dependence of the phase
fluctuations on the trapping geometry of the BEC.
\\ ( ,  367kb)
Paper: cond-mat/0601542
replaced with revised version Mon, 30 Jan 2006 11:38:20 GMT   (51kb)
Title: A two-channel R-matrix analysis of magnetic field induced Feshbach
Authors: Nicolai Nygaard, Barry I. Schneider and Paul S. Julienne
Comments: Added references. 11 pages, 6 figures. For additional information see
Subj-class: Other; Atomic Physics
\\ ( ,  51kb)
Paper: cond-mat/0601681
Date: Mon, 30 Jan 2006 21:18:20 GMT   (220kb)
Title: Exact Study of the 1D Boson Hubbard Model with a Superlattice Potential
Authors: V.G. Rousseau, M. Rigol, F. H\'ebert, D.P. Arovas, G.G. Batrouni, R.T.
Comments: 12 pages, 22 figures
Subj-class: Other; Strongly Correlated Electrons
   We use Quantum Monte Carlo simulations and exact diagonalization to explore
the phase diagram of the Bose-Hubbard model with an additional superlattice
potential. We first analyze the properties of superfluid and insulating phases
present in the hard-core limit where an exact analytic treatment is possible
via the Jordan-Wigner transformation. The extension to finite on-site
interaction is achieved by means of quantum Monte Carlo simulations. We
determine insulator/superfluid phase diagrams as functions of the on-site
repulsive interaction, superlattice potential strength, and filling, finding
that insulators with fractional occupation numbers, which are present in the
hard-core case, extend deep into the soft-core region. Furthermore, at integer
fillings, we find that the competition between the on-site repulsion and the
superlattice potential can produce a phase transition between a Mott insulator
and a charge density wave insulator, with an intermediate superfluid phase. Our
results are relevant to the behavior of ultracold atoms in optical
superlattices which are beginning to be studied experimentally.
\\ ( ,  220kb)
Paper: cond-mat/0601690
Date: Tue, 31 Jan 2006 07:19:56 GMT   (811kb)
Title: Fringe spacing and phase of interfering matter waves
Authors: O. Vainio, C. J. Vale, M. J. Davis, N. R. Heckenberg, and H.
Comments: 4 pages, 3 figures
Subj-class: Other
   We experimentally investigate the outcoupling of atoms from Bose-Einstein
condensates using two radio-frequency (rf) fields in the presence of gravity.
We show that the fringe separation in the resulting interference pattern
derives entirely from the energy difference between the two rf fields and not
the gravitational potential difference. We subsequently demonstrate how the
phase and polarisation of the rf radiation directly control the phase of the
matter wave interference and provide a semi-classical interpretation of the
\\ ( ,  811kb)
Paper: cond-mat/0601695
Date: Tue, 31 Jan 2006 11:38:27 GMT   (55kb)
Title: Vortex-lattice melting in a one-dimensional optical lattice
Authors: Michiel Snoek and H.T.C. Stoof
Comments: 4 pages, 4 figures
Report-no: ITP-UU-06/04
Subj-class: Mesoscopic Systems and Quantum Hall Effect
   We investigate quantum fluctuations of a vortex lattice in a one-dimensional
optical lattice. Our method gives full access to all the modes of the vortex
lattice and we discuss in particular the Bloch bands of the Tkachenko modes.
Because of the small number of particles in the pancake Bose-Einstein
condensates at every site of the optical lattice, finite-size effects become
very important. Therefore, the fluctuations in the vortex positions are
inhomogeneous and the melting of the lattice occurs from the outside inwards.
Tunneling between neighbouring pancakes substantially reduces the inhomogeneity
as well as the size of the fluctuations.
\\ ( ,  55kb)
Paper: cond-mat/0601714
Date: Tue, 31 Jan 2006 18:22:16 GMT   (875kb)
Title: Spatial effects in superradiant Rayleigh scattering from Bose-Einstein
Authors: O. Zobay and Georgios M. Nikolopoulos
Comments: 14 pages, 13 figures
Subj-class: Other
Journal-ref: Phys. Rev. A 73, 013620 (2006)
DOI: 10.1103/PhysRevA.73.013620
   We present a detailed theoretical analysis of superradiant Rayleigh
scattering from atomic Bose-Einstein condensates. A thorough investigation of
the spatially resolved time-evolution of optical and matter-wave fields is
performed in the framework of the semiclassical Maxwell-Schroedinger equations.
Our theory is not only able to explain many of the known experimental
observations, e.g., the behavior of the atomic side-mode distributions, but
also provides further detailed insights into the coupled dynamics of optical
and matter-wave fields. To work out the significance of propagation effects, we
compare our results to other theoretical models in which these effects are
\\ ( ,  875kb)
Paper: cond-mat/0511113
replaced with revised version Tue, 31 Jan 2006 11:57:08 GMT   (511kb)
Title: Intense slow beams of bosonic potassium isotopes
Authors: J. Catani, P. Maioli, L. De Sarlo, F. Minardi, and M. Inguscio
Comments: Updated references, 1 figure added, 10 pages, 9 figures
Subj-class: Other
\\ ( ,  511kb)
Paper: quant-ph/0601208
Date: Tue, 31 Jan 2006 14:13:47 GMT   (215kb)
Title: Entanglement And Cross-Correlations In Cavity QED
Authors: P. R. Rice, J. Gea-Banacloche, M. L. Terraciano, D. L. Freimund, L. A.
Comments: 13 pages, 3 figures
   We investigate entanglement in an open quantum system, specifically a single
atom in a driven optical cavity with cavity loss and spontaneous emission. In
the weak driving limit, the system reaches a pure state in the steady state. We
find that any normalized cross-correlation function, of the type historically
considered in quantum optics, is an indicator of the entanglement in a system.
In particular we find that the zero delay intensity-field cross correlation is
proportional to the entanglement of formation for weak driving fields. Other
correlation functions are considered as indicators, or witnesses, of
\\ ( ,  215kb)
Paper: quant-ph/0602006
Date: Wed, 1 Feb 2006 13:26:23 GMT   (527kb)
Title: A cavity-QED scheme for Heisenberg-limited interferometry
Authors: David Vitali, Stefan Kuhr, Michel Brune, Jean-Michel Raimond
Comments: 13 pages, 7 figures
   We propose a Ramsey interferometry experiment using an entangled state of N
atoms to reach the Heisenberg limit for the estimation of an atomic phase shift
if the atom number parity is perfectly determined. In a more realistic
situation, due to statistical fluctuations of the atom source and the finite
detection efficiency, the parity is unknown. We then achieve about half the
Heisenberg limit. The scheme involves an ensemble of circular Rydberg atoms
which dispersively interact successively with two initially empty microwave
cavities. The scheme does not require very high-Q cavities. An experimental
realization with about ten entangled Rydberg atoms is achievable with state of
art apparatuses.
\\ ( ,  527kb)
Paper: quant-ph/0602010
Date: Wed, 1 Feb 2006 13:57:20 GMT   (158kb)
Title: Optimized production of large Bose Einstein Condensates
Authors: D. Comparat (LAC), A. Fioretti (LAC), G. Stern (LAC), E. Dimova (LAC),
   B. Laburthe Tolra (LPL), P. Pillet (LAC)
Comments: 14 pages
Proxy: ccsd ccsd-00018383
   We suggest different simple schemes to efficiently load and evaporate a
''dimple'' crossed dipolar trap. The collisional processes between atoms which
are trapped in a reservoir load in a non adiabatic way the dimple. The
reservoir trap can be provided either by a dark SPOT Magneto Optical Trap, the
(aberrated) laser beam itself or by a quadrupolar or quadratic magnetic trap.
Optimal parameters for the dimple are derived from thermodynamical equations
and from loading time, including possible inelastic and Majorana losses. We
suggest to load at relatively high temperature a tight optical trap. Simple
evaporative cooling equations, taking into account gravity, the possible
occurrence of hydrodynamical regime, Feshbach resonance processes and three
body recombination events are given. To have an efficient evaporation the
elastic collisional rate (in s$^{-1}$) is found to be on the order of the
trapping frequency and lower than one hundred times the temperature in
micro-Kelvin. Bose Einstein condensates with more than $10^7$ atoms should be
obtained in much less than one second starting from an usual MOT setup.
\\ ( ,  158kb)
Paper: quant-ph/0602013
Date: Wed, 1 Feb 2006 16:17:27 GMT   (217kb)
Title: Transversal laser excitation of atoms in a waveguide
Authors: I. Lizuain, A. Ruschhaupt, J. G. Muga
Comments: 10 pages, 9 figures
   We investigate the effect of a laser shining perpendicularly to a waveguide
channeling two-level atoms. For weak transversal coupling the excitation of
transverse atomic levels occurs at avoided crossings associated with "Rabi
resonances" in which the Rabi frequency coincides with the transition frequency
between the transverse levels.
\\ ( ,  217kb)
Paper: quant-ph/0602017
Date: Wed, 1 Feb 2006 20:16:20 GMT   (156kb)
Title: Controlling Polar Molecules in Optical Lattices
Authors: S. Kotochigova, E. Tiesinga
   We investigate theoretically the interaction of polar molecules with optical
lattices and microwave fields. We demonstrate the existence of frequency
windows in the optical domain where the complex internal structure of the
molecule does not influence the trapping potential of the lattice. In such
frequency windows the Franck-Condon factors are so small that near-resonant
interaction of vibrational levels of the molecule with the lattice fields have
a negligible contribution to the polarizability and light-induced decoherences
are kept to a minimum. In addition, we show that microwave fields can induce a
tunable dipole-dipole interaction between ground-state rotationally symmetric
(J=0) molecules. A combination of a carefully chosen lattice frequency and
microwave-controlled interaction between molecules will enable trapping of
polar molecules in a lattice and possibly realize molecular quantum logic
gates. Our results are based on ab initio relativistic electronic structure
calculations of the polar KRb and RbCs molecules combined with calculations of
their rovibrational motion.
\\ ( ,  156kb)
Paper: physics/0602011
Date: Wed, 1 Feb 2006 19:20:19 GMT   (108kb)
Title: Demonstration of an Electron Electric Dipole Moment Experiment Using
   Electric-Field Quantization in a Cesium Cold Atom Fountain
Authors: Jason M. Amini, Charles T. Munger Jr., Harvey Gould
Comments: 4 pages, 4 figures plus bibtex
Subj-class: Atomic Physics
   A Cs fountain electron electric dipole moment (EDM) experiment using
electric-field quantization is demonstrated. With magnetic fields reduced to
200 pT or less, the electric field lifts the degeneracy between hyperfine
levels of different|mF| and, along with the slow beam and fountain geometry,
suppresses systematics from motional magnetic fields. Transitions are induced
and the atoms polarized and analyzed in field-free regions. The feasibility of
reaching a sensitivity to an electron EDM of 2 x 10 exp(-50) C-m [1.3 x 10
exp(-29) e-cm] in a cesium fountain experiment is discussed.
\\ ( ,  108kb)
Paper: cond-mat/0602032
Date: Wed, 1 Feb 2006 21:01:57 GMT   (23kb)
Title: Fermi surfaces and Luttinger's theorem in paired fermion systems
Authors: Subir Sachdev and Kun Yang
Comments: 7 pages with one figure embedded
Subj-class: Superconductivity
   We discuss ground state properties of a mixture of two fermion species which
can bind to form a molecular boson. When the densities of the fermions are
unbalanced, one or more Fermi surfaces can appear: we describe the constraints
placed by Luttinger's theorem on the volumes enclosed by these surfaces in such
Bose-Fermi mixtures. We also discuss the nature of the quantum phase
transitions involving changes in the number of Fermi surfaces.
\\ ( ,  23kb)
Paper: cond-mat/0602037
Date: Thu, 2 Feb 2006 20:45:05 GMT   (156kb)
Title: Validity of the Lowest Landau Level Approximation for Rotating Bose
Authors: Alexis G. Morris and David L. Feder
Comments: 8 pages, 9 figures
Subj-class: Mesoscopic Systems and Quantum Hall Effect
   The energy spectra for an ultracold rotating Bose gas in a harmonic trap are
calculated exactly for small systems, allowing the atoms to occupy several
Landau levels. Two vortex-like states and two strongly correlated states (the
Pfaffian and Laughlin) are considered in detail. In particular, their critical
rotation frequencies and energy gaps are determined as a function of particle
number, interaction strength, and the number of Landau levels occupied (up to
three). For the vortex-like states, the Lowest Landau level (LLL) approximation
is justified only if the interaction strength decreases with the number of
particles; nevertheless, the constant of proportionality increases rapidly with
the angular momentum per particle. For the strongly correlated states, however,
the interaction strength can \emph{increase} with particle number without
violating the LLL condition. The results suggest that in large systems, the
Pfaffian and Laughlin states might be stabilized at rotation frequencies well
below the centrifugal limit for sufficiently large interaction strengths, with
energy gaps a significant fraction of the trap energy.
\\ ( ,  156kb)
Paper: cond-mat/0602048
Date: Thu, 2 Feb 2006 16:09:58 GMT   (166kb)
Title: Coherent transport of cold atoms in angle-tuned optical lattices
Authors: Roberto Franzosi, Matteo Cristiani, Carlo Sias, Ennio Arimondo
Comments: 7 pages, 5 figures
Subj-class: Other
   Optical lattices with a large spacing between the minima of the optical
potential can be created using the angle-tuned geometry where the 1-D periodic
potential is created by two propagating laser beams intersecting at an angle
different from $\pi$. The present work analyzes the coherent transport for the
case of that geometry. We show that the potential depth can be kept constant
during the transport by choosing a \emph{magic} value for the laser wavelength.
This value agrees with that of the counterpropagating laser case, thus
resulting independent on the lattice geometry. Moreover, we find that this
scheme can be used to implement controlled collision experiments under special
geometrical conditions. Finally we study the transport of hyperfine-Zeeman
states of rubidium 87.
\\ ( ,  166kb)
Paper: cond-mat/0602055
Date: Thu, 2 Feb 2006 17:37:51 GMT   (28kb)
Title: Bose Einstein Condensation of incommensurate solid 4He
Authors: D. E. Galli and L. Reatto
Comments: 4 pages, 2 figures
Subj-class: Other; Statistical Mechanics
   It is pointed out that simulation computation of energy performed so far
cannot be used to decide if the ground state of solid 4He has the number of
lattice sites equal to the number of atoms (commensurate state) or if it is
different (incommensurate state). The best variational wave function, a shadow
wave function, gives an incommensurate state but the equilibrium concentration
of vacancies remains to be determined. In order to investigate the presence of
a supersolid phase we have computed the one--body density matrix in solid 4He
for the incommensurate state by means of the exact Shadow Path Integral Ground
State projector method. We find a vacancy induced Bose Einstein condensation of
about 0.23 atoms per vacancy at a pressure of 54 bar. This means that bulk
solid 4He is supersolid at low enough temperature if the exact ground state is
\\ ( ,  28kb)
Paper: cond-mat/0512010
replaced with revised version Thu, 2 Feb 2006 12:38:18 GMT   (422kb)
Title: Sound velocity and dimensional crossover in a superfluid Fermi gas in an
   optical lattice
Authors: T. Koponen, J.-P. Martikainen, J. Kinnunen, and P. Torma
Comments: 16 pages, 9 figures, v2: minor corrections to the text, replaced one
Subj-class: Superconductivity
\\ ( ,  422kb)
Received on Fri Feb 03 2006 - 16:47:46 EST

This archive was generated by hypermail 2.2.0 : Thu May 08 2008 - 11:51:41 EST