# Matt's arXiv selection: week ending 27th July 2007.

From: Matthew Davis <mdavis_at_physics.uq.edu.au>
Date: Tue, 31 Jul 2007 17:06:39 +1000 (EST)

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

Hello again,

I'm very pleased to say that you are now entirely up to date (as at the end of
last week!) This is a weight off my mind... my wife is due to give birth to our
second child any day now and I would had to leave you in the lurch!

Quite a few interesting papers this week... 24 new preprints and 7 replacements:

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arXiv:0707.3065
Date: Fri, 20 Jul 2007 12:58:52 GMT (271kb)

Title: Exact vortex nucleation and cooperative vortex tunneling in dilute BECs
Authors: M.I. Parke, N.K. Wilkin, J.M.F. Gunn and A. Bourne
Categories: cond-mat.mes-hall cond-mat.str-el
\\
With the imminent advent of mesoscopic rotating BECs in the lowest Landau
level (LLL) regime, we explore LLL vortex nucleation. An exact many-body
analysis is presented in a weakly elliptical trap for up to 400 particles.
Striking non-mean field features are exposed. For example, near the critical
rotation frequency the energy levels group in neighbouring pairs, approaching
each other with exponential accuracy. A physical interpretation is provided by
requantising a mean field theory, revealing two vortices {\em cooperatively}
tunneling between classically degenerate energy minima. The variation of the
tunnel splitting near the nucleation frequency is well described in terms of
variation with frequency, particle number and ellipticity.
\\ ( http://arxiv.org/abs/0707.3065 , 271kb)
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arXiv:0707.3131
Date: Fri, 20 Jul 2007 19:14:19 GMT (229kb)

Title: Dynamics of Bloch Oscillations in Disordered Lattice Potentials
Authors: T. Schulte, S. Drenkelforth, G. Kleine B\"uning, W. Ertmer, J. Arlt,
M. Lewenstein, and L. Santos
Categories: cond-mat.other cond-mat.dis-nn
\\
We present a detailed analysis of the dynamics of Bloch oscillations of
Bose-Einstein condensates in disordered lattice potentials. Due to the disorder
and the interparticle interactions these oscillations undergo a dephasing,
reflected in a damping of the center of mass oscillations, which should be
observable under realistic experimental conditions. The interplay between
interactions and disorder is far from trivial, ranging from an
interaction-enhanced damping due to modulational instability for strong
interactions, to an interaction-reduced damping due to a dynamical screening of
the disorder potential.
\\ ( http://arxiv.org/abs/0707.3131 , 229kb)
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arXiv:0707.2963
Date: Thu, 19 Jul 2007 20:33:13 GMT (238kb,D)

Title: Two-body transients in coupled atomic-molecular BECs
Authors: Pascal Naidon, Eite Tiesinga and Paul S. Julienne
Categories: physics.atom-ph
\\
We discuss the dynamics of an atomic Bose-Einstein condensate when pairs of
atoms are converted into molecules by single-color photoassociation. Three main
regimes are found and it is shown that they can be understood on the basis of
time-dependent two-body theory. In particular, the so-called rogue dissociation
regime [Phys. Rev. Lett., 88, 090403 (2002)], which has a density-dependent
limit on the photoassociation rate, is identified with a transient regime of
the two-atom dynamics exhibiting universal properties. Finally, we illustrate
how these regimes could be explored by photoassociating condensates of
alkaline-earth atoms.
\\ ( http://arxiv.org/abs/0707.2963 , 238kb)
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arXiv:0707.3003
Date: Fri, 20 Jul 2007 06:21:40 GMT (591kb)

Title: Energy Dependence of Scattering Ground State Polar Molecules
Authors: Christopher Ticknor
Categories: physics.atom-ph
\\
We explore the total cross section of ground state polar molecules in an
electric field at various energies, focusing on RbCs and RbK. An external
electric field polarizes the molecules and induces strong dipolar interactions
leading to non-zero partial waves contributing to the scattering even as the
collision energy goes to zero. This results in the need to compute scattering
problems with many different values of total M to converge the total cross
section. An accurate and efficient approximate total cross section is
introduced and used to study the low field temperature dependence. To
understand the scattering of the polar molecules we compare a semi-classical
cross section with quantum unitarity limit. This comparison leads to the
ability to characterize the scattering based on the value of the electric field
and the collision energy.
\\ ( http://arxiv.org/abs/0707.3003 , 591kb)
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arXiv:0707.3117
Date: Fri, 20 Jul 2007 18:14:25 GMT (229kb)

Title: Cavity cooling of a nanomechanical resonator by light scattering
Authors: Ivan Favero and Khaled Karrai
Categories: physics.optics
\\
We present a novel method for opto-mechanical cooling of sub-wavelength sized
nanomechanical resonators. Our scheme uses a high finesse Fabry-Perot cavity of
small mode volume, within which the nanoresonator is acting as a
position-dependant perturbation by scattering. In return, the back-action
induced by the cavity affects the nanoresonator dynamics. We investigate such
cavity cooling by scattering in two limits, namely in the lossy regime and in
the purely dispersive regime.
\\ ( http://arxiv.org/abs/0707.3117 , 229kb)
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arXiv:0707.3140
Date: Fri, 20 Jul 2007 20:14:14 GMT (53kb)

Title: Interaction-controlled transport of an ultracold Fermi gas
Authors: Niels Strohmaier, Yosuke Takasu, Kenneth Guenter, Robert Joerdens,
Michael Koehl, Henning Moritz, and Tilman Esslinger
Categories: cond-mat.str-el
Comments: 4 pages, 4 Postscript figures
\\
We explore the transport properties of an interacting Fermi gas in a
three-dimensional optical lattice. The center of mass dynamics of the atoms
after a sudden displacement of the trap minimum is monitored for different
interaction strengths and lattice fillings. With increasingly strong attractive
interactions the weakly damped oscillation, observed for the non-interacting
case, turns into a slow relaxational drift. Tuning the interaction strength
during the evolution allows us to dynamically control the transport behavior.
Strong attraction between the atoms leads to the formation of local pairs with
a reduced tunneling rate. The interpretation in terms of pair formation is
supported by a measurement of the number of doubly occupied lattices sites.
This quantity also allows us to determine the temperature in the lattice to be
as low as $(27\pm2)%$ of the Fermi temperature.
\\ ( http://arxiv.org/abs/0707.3140 , 53kb)
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arXiv:0707.3209
Date: Mon, 23 Jul 2007 14:50:57 GMT (61kb)

Title: Commensurability effects for fermionic atoms trapped in 1D optical
lattices
Authors: Rafael A. Molina, Jorge Dukelsky, Peter Schmitteckert
Categories: cond-mat.str-el
Comments: Accepted for publication in Physical Review Letters
\\
Fermionic atoms in two different hyperfine states confined in optical
lattices show strong commensurability effects due to the interplay between the
atomic density wave (ADW) ordering and the lattice potential. We show that
spatially separated regions of commensurable and incommensurable phases can
coexist. The commensurability between the harmonic trap and the lattice sites
can be used to control the amplitude of the atomic density waves in the central
region of the trap.
\\ ( http://arxiv.org/abs/0707.3209 , 61kb)
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arXiv:0707.3320
Date: Mon, 23 Jul 2007 06:42:28 GMT (10kb)

Title: Discontinuity in the specific heat of a weakly interacting Bose gas
Authors: Sang-Hoon Kim
Categories: cond-mat.stat-mech
\\
We produce the discontinuity in the specific heat of a homogeneous, dilute,
and weakly interacting Bose gas in a short-wavelength range with a simple
statistical method. The magnitude of the discontinuity at the phase transition
temperature is obtained as a function of the density and scattering length
analytically.
\\ ( http://arxiv.org/abs/0707.3320 , 10kb)
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arXiv:0707.3593
Date: Tue, 24 Jul 2007 16:20:54 GMT (176kb)

Title: Finite-Temperature Collective Dynamics of a Fermi Gas in the BEC-BCS
Crossover
Authors: M. J. Wright, S. Riedl, A. Altmeyer, C. Kohstall, E. R. Sanchez
Guajardo, J. Hecker Denschlag, R. Grimm
Categories: cond-mat.other
\\
We report on experimental studies on the collective behavior of a strongly
interacting Fermi gas with tunable interactions and variable temperature. A
scissors mode excitation in an elliptical trap is used to characterize the
dynamics of the quantum gas in terms of hydrodynamic or near-collisionless
behavior. We obtain a crossover phase diagram for collisional properties,
showing a large region where a non-superfluid strongly interacting gas shows
hydrodynamic behavior. In a narrow interaction regime on the BCS side of the
crossover, we find a novel temperature-dependent damping peak, suggesting a
relation to the superfluid phase transition.
\\ ( http://arxiv.org/abs/0707.3593 , 176kb)
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arXiv:0707.3599
Date: Tue, 24 Jul 2007 16:45:19 GMT (881kb)

Title: Theory for p-Wave Feshbach Molecules
Authors: K. B. Gubbels and H. T. C. Stoof
Categories: cond-mat.supr-con
\\
We determine the physical properties of \emph{p}-wave Feshbach molecules in
doubly spin-polarized $^{40}$K and find excellent agreement with recent
experiments. We show that these molecules have a large probability $Z$ to be in
the closed channel or bare molecular state responsible for the Feshbach
resonance. In the superfluid state this allows for an observation of Rabi
oscillations between the molecular and atomic components of the Bose-Einstein
condensed pairs, which contains a characteristic sign of the quantum phase
transition that occurs as a function of applied magnetic field.
\\ ( http://arxiv.org/abs/0707.3599 , 881kb)
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arXiv:0707.3630
Date: Tue, 24 Jul 2007 21:28:44 GMT (11kb)

Title: Molecular production at a wide Feshbach resonance in Fermi-gas of cooled
atoms
Authors: Deqiang Sun, Ar. Abanov, and V.L. Pokrovsky
Categories: cond-mat.other
\\
The problem of molecular production from degenerate gas of fermions at a wide
Feshbach resonance, in a single-mode approximation, is reduced to the linear
Landau-Zener problem for operators. The strong interaction leads to significant
renormalization of the gap between adiabatic levels. In contrast to static
problem the close vicinity of exact resonance does not play substantial role.
Two main physical results of our theory is the high sensitivity of molecular
production to the initial value of magnetic field and generation of a large BCS
condensate distributed over a broad range of momenta in inverse process of the
molecule dissociation.
\\ ( http://arxiv.org/abs/0707.3630 , 11kb)
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arXiv:0707.3633
Date: Tue, 24 Jul 2007 20:00:30 GMT (223kb)

Title: Do mixtures of bosonic and fermionic atoms adiabatically heat up in
optical lattices?
Authors: M. Cramer, S. Ospelkaus, C. Ospelkaus, K. Bongs, K. Sengstock, J.
Eisert
Categories: cond-mat.stat-mech
\\
Mixtures of bosonic and fermionic atoms in optical lattices provide a
promising arena to study strongly correlated systems. In experiments realizing
such mixtures in the quantum degenerate regime the temperature is a key
parameter. In this work, we investigate the intrinsic heating and cooling
effects due to an entropy-preserving raising of the optical lattice potential.
We analyze this process, identify the generic behavior valid for a wide range
of parameters, and discuss it quantitatively for the recent experiments with
87Rb and 40K atoms. In the absence of a lattice, we treat the bosons in the
Hartree-Fock-Bogoliubov-Popov-approximation, including the fermions in a
self-consistent mean field interaction. In the presence of the full
three-dimensional lattice, we use a strong coupling expansion. As a result of
the presence of the fermions, the temperature of the mixture after the lattice
ramp-up is always higher than for the pure bosonic case. This sheds light onto
a key point in the analysis of recent experiments.
\\ ( http://arxiv.org/abs/0707.3633 , 223kb)
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arXiv:0707.3698
Date: Wed, 25 Jul 2007 09:55:13 GMT (614kb,D)

Title: Angular momentum exchange between coherent light and matter fields
Authors: T. P. Simula, N. Nygaard, S. X. Hu, L. A. Collins, B. I. Schneider,
and K. Molmer
Categories: cond-mat.soft
\\
Full, three dimensional, time-dependent simulations are presented
demonstrating the quantized transfer of angular momentum to a Bose-Einstein
condensate from a laser carrying orbital angular momentum in a
Laguerre-Gaussian mode. The process is described in terms of coherent Bragg
scattering of atoms from a chiral optical lattice. The transfer efficiency and
the angular momentum content of the output coupled vortex state are analyzed
and compared with a recent experiment.
\\ ( http://arxiv.org/abs/0707.3698 , 614kb)
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arXiv:0707.3760
Date: Wed, 25 Jul 2007 15:03:06 GMT (34kb)

Title: Striped phases in two dimensional dipole systems
Authors: Alessandro Giuliani, Joel L. Lebowitz and Elliott H. Lieb
Categories: cond-mat.stat-mech
\\
We prove that a system of discrete 2D in-plane dipoles with four possible
orientations, interacting via a 3D dipole-dipole interaction plus a nearest
neighbor ferromagnetic term, has periodic striped ground states. As the
strength of the ferromagnetic term is increased, the size of the stripes in the
ground state increases, becoming infinite, i.e., giving a ferromagentic ground
state, when the ferromagentic interaction exceeds a certain critical value. We
also give a rigorous proof of the reorientation transition in the ground state
of a 2D system of discrete dipoles with six possible orientations, interacting
via a 3D dipole-dipole interaction plus a nearest neighbor antiferromagnetic
term. As the strength of the antiferromagnetic term is increased the ground
state flips from being striped and in-plane to being staggered and
out-of-plane. An example of a rotator model with a sinusoidal ground state is
also discussed.
\\ ( http://arxiv.org/abs/0707.3760 , 34kb)
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arXiv:0707.3646
Date: Tue, 24 Jul 2007 23:19:13 GMT (316kb)

Title: Transport quantum logic gates for trapped ions
Authors: D. Leibfried, E. Knill, C. Ospelkaus and D. J. Wineland
Categories: quant-ph
\\
Many efforts are currently underway to build a device capable of large scale
quantum information processing (QIP). Whereas QIP has been demonstrated for a
few qubits in several systems, many technical difficulties must be overcome in
order to construct a large-scale device. In one proposal for large-scale QIP,
trapped ions are manipulated by precisely controlled light pulses and moved
through and stored in multizone trap arrays. The technical overhead necessary
to precisely control both the ion geometrical configurations and the laser
interactions is demanding. Here we propose methods that significantly reduce
the overhead on laser beam control for performing single and multiple qubit
operations on trapped ions. We show how a universal set of operations can be
implemented by controlled transport of ions through stationary laser beams. At
the same time, each laser beam can be used to perform many operations in
parallel, potentially reducing the total laser power necessary to carry out QIP
tasks. The overall setup necessary for implementing transport gates is simpler
than for gates executed on stationary ions. We also suggest a transport-based
two-qubit gate scheme utilizing microfabricated permanent magnets that can be
executed without laser light.
\\ ( http://arxiv.org/abs/0707.3646 , 316kb)
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arXiv:0707.3707
Date: Wed, 25 Jul 2007 10:38:03 GMT (949kb)
Title: Storing images in warm atomic vapor
Authors: M. Shuker, O. Firstenberg, R. Pugatch, A. Ron, N. Davidson
Categories: quant-ph
\\
Back in 1844 W. H. F. Talbot co-invented the photographic plate since he
wanted to capture "fairy pictures, creations of a moment, and destined as
rapidly to fade away", seen in his camera obscura. Indeed, a photographic
process, uses a photochemical or a photoelectric response in order to record
images irreversibly onto a given media. The invention of the hologram by D.
Gabor broadened this capability, by enabling the recording of both the
amplitude and phase information of a two-dimensional light field, thus enabling
for example, the reconstruction of three dimensional images. Here we report a
method for reversibly capturing complex three-dimensional light fields using
electromagnetically induced transparency (EIT) in room temperature rubidium
vapor. We store and retrieve a short light pulse that carries a transverse
two-dimensional image by converting the amplitude and phase of the light field
into atomic coherences. We show that both the temporal and transverse
properties of the light field are preserved. As a first example, we store
images of digits for several micro-seconds. By introducing a phase-shift
technique, equivalent to the optical method known as "phase-shift lithography",
we further show that we can significantly improve the visibility of certain
retrieved images against diffusion of the atoms, which also serves as proof
that the phase of the image was stored as well. This experiment demonstrate
that three dimensional complex light fields can be stored in alkali vapor, by
employing the storage-of-light technique using EIT. This may open the
possibility of storing an array of qubits in a single alkali vapor cell.
\\ ( http://arxiv.org/abs/0707.3707 , 949kb)
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arXiv:0707.3927
Date: Thu, 26 Jul 2007 14:12:26 GMT (49kb)
Title: Dynamic structure factor of Fermi superfluid in the BEC-BCS crossover
Authors: Tarun Kanti Ghosh
Categories: cond-mat.other
Comments: To appear in Physical Review A
\\
We consider cigar shaped Fermi superfluid in the BEC-BCS crossover. Using
polytropic form of equation of state, we derive low energy multibranch bosonic
excitations and the corresponding density fluctuations in three different
regimes along the crossover, namely weak-coupling BCS, unitarity and molecular
BEC regimes. Bragg spectroscopy can be used to probe the multibranch nature of
the low energy bosonic excitations by measuring dynamic structure factor.
Therefore, we calculate dynamic structure factor in those three different
regimes. In the Bragg spectroscopy, an actual observable is momentum imparted
to the superfluid due to the Bragg potential. We also present results of the
momentum imparted to the superfluid due to the Bragg pulses.
\\ ( http://arxiv.org/abs/0707.3927 , 49kb)
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arXiv:0707.3930
Date: Thu, 26 Jul 2007 14:28:03 GMT (57kb)

Title: Superfluid-Insulator and Roughening Transitions in Domain Walls
Authors: \c{S}. G. S\"oyler, B. Capogrosso-Sansone, N. V. Prokof'ev, B. V.
Svistunov
Categories: cond-mat.other cond-mat.stat-mech
\\
We have performed quantum Monte Carlo simulations to investigate the
superfluid behavior of one- and two-dimensional interfaces separating
checkerboard solid domains. The system is described by the hard-core
Bose-Hubbard Hamiltonian with nearest-neighbor interaction. In accordance with
Ref.1, we find that (i) the interface remains superfluid in a wide range of
interaction strength before it undergoes a superfluid-insulator transition;
(ii) in one dimension, the transition is of the Kosterlitz-Thouless type and is
accompanied by the roughening transition, driven by proliferation of charge 1/2
quasiparticles; (iii) in two dimensions, the transition belongs to the 3D U(1)
universality class and the interface remains smooth. Similar phenomena are
expected for domain walls in quantum antiferromagnets.
\\ ( http://arxiv.org/abs/0707.3930 , 57kb)
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arXiv:0707.3984
Date: Thu, 26 Jul 2007 19:04:02 GMT (611kb)

Title: Coarse-Grained Finite-Temperature Theory for the Condensate in Optical
Lattices
Authors: Satoru Konabe and Tetsuro Nikuni
Categories: cond-mat.other
Comments: 38 pages, 2 figures. Submitted to Journal of Low Temperature Physics
\\
In this work, we derive a coarse-grained finite-temperature theory for a Bose
condensate in a one-dimensional optical lattice, in addition to a confining
harmonic trap potential. We start from a two-particle irreducible (2PI)
effective action on the Schwinger-Keldysh closed-time contour path. In
principle, this action involves all information of equilibrium and
non-equilibrium properties of the condensate and noncondensate atoms. By
assuming an ansatz for the variational function, i.e., the condensate order
parameter in an effective action, we derive a coarse-grained effective action,
which describes the dynamics on the length scale much longer than a lattice
constant. Using the variational principle, coarse-grained equations of motion
for the condensate variables are obtained. These equations include a
dissipative term due to collisions between condensate and noncondensate atoms,
as well as noncondensate mean-field. To illustrate the usefulness of our
formalism, we discuss a Landau instability of the condensate in optical
lattices by using the coarse-grained generalized Gross-Pitaevskii
hydrodynamics. We found that the collisional damping rate due to collisions
between the condensate and noncondensate atoms changes sign when the condensate
velocity exceeds a renormalized sound velocity, leading to a Landau instability
consistent with the Landau criterion. Our results in this work give an insight
into the microscopic origin of the Landau instability.
\\ ( http://arxiv.org/abs/0707.3984 , 611kb)
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arXiv:0707.3985
Date: Thu, 26 Jul 2007 19:07:12 GMT (922kb)

Title: Direct Observation of Second Order Atom Tunnelling
Authors: S. Foelling, S. Trotzky, P. Cheinet, M. Feld, R. Saers, A. Widera, T.
Mueller and I. Bloch
Categories: cond-mat.other
Comments: 18 pages, 4 figures, accepted for publication in Nature
\\
Tunnelling of material particles through a classically impenetrable barrier
constitutes one of the hallmark effects of quantum physics. When interactions
between the particles compete with their mobility through a tunnel junction,
intriguing novel dynamical behaviour can arise where particles do not tunnel
independently. In single-electron or Bloch transistors, for example, the
tunnelling of an electron or Cooper pair can be enabled or suppressed by the
presence of a second charge carrier due to Coulomb blockade. Here we report on
the first direct and time-resolved observation of correlated tunnelling of two
interacting atoms through a barrier in a double well potential. We show that
for weak interactions between the atoms and dominating tunnel coupling,
individual atoms can tunnel independently, similar to the case in a normal
Josephson junction. With strong repulsive interactions present, two atoms
located on one side of the barrier cannot separate, but are observed to tunnel
together as a pair in a second order co-tunnelling process. By recording both
the atom position and phase coherence over time, we fully characterize the
tunnelling process for a single atom as well as the correlated dynamics of a
pair of atoms for weak and strong interactions. In addition, we identify a
conditional tunnelling regime, where a single atom can only tunnel in the
presence of a second particle, acting as a single atom switch. Our work
constitutes the first direct observation of second order tunnelling events with
ultracold atoms, which are the dominating dynamical effect in the strongly
interacting regime. Similar second-order processes form the basis of
superexchange interactions between atoms on neighbouring lattice sites of a
periodic potential, a central component of quantum magnetism.
\\ ( http://arxiv.org/abs/0707.3985 , 922kb)
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arXiv:0707.3821
Date: Wed, 25 Jul 2007 20:49:28 GMT (25kb)

Title: One-way quantum computing in optical lattices with many atom addressing
Authors: Timothy P. Friesen and David L. Feder
Categories: quant-ph
\\
One of the fundamental conditions for one-way quantum computation (1WQC) is
the ability to make sequential measurements on isolated qubits that comprise
the highly entangled resource for 1WQC, the cluster state. This has been a
significant impediment in the implementation of 1WQC with ultracold atoms
confined in optical lattices, because the width of the measuring lasers is
generally much greater than the atomic (qubit) spacing. We demonstrate that
deterministic 1WQC is nevertheless possible, with a polynomial increase in the
number of operations, as long as the center of the beams can be positioned with
high accuracy. Extending the number of cluster atoms, the scheme is also able
to compensate for accidental measurements of an arbitrary number of nearby
qubits.
\\ ( http://arxiv.org/abs/0707.3821 , 25kb)
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arXiv:0707.3834
Date: Wed, 25 Jul 2007 22:20:27 GMT (557kb)

Title: Spin squeezing in optical lattice clocks via lattice-based QND
measurements
Authors: D. Meiser, Jun Ye, and M. J. Holland
Categories: quant-ph
\\
Quantum projection noise limits the best achievable precision of optical
atomic clocks based on lattice-confined neutral atoms. Squeezing the collective
atomic pseudo-spin via measurement of the clock state populations during Ramsey
interrogation suppresses the projection noise. We show here that the lattice
laser field can be used to perform ideal quantum nondemolition measurements
without clock shifts or decoherence and explore the feasibility of such an
approach in theory with the lattice field confined in a ring-resonator.
Detection of the motional sideband due to the atomic vibration in the lattice
wells can yield signal sizes a hundredfold above the projection noise limit.
\\ ( http://arxiv.org/abs/0707.3834 , 557kb)
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arXiv:0707.3880
Date: Thu, 26 Jul 2007 19:03:50 GMT (472kb)

Title: Progressive field-state collapse and quantum non-demolition photon
counting
Authors: Christine Guerlin (LKB - Lhomond), Julien Bernu (LKB - Lhomond),
Samuel Del\'eglise (LKB - Lhomond), Cl\'ement Sayrin (LKB - Lhomond),
S\'ebastien Gleyzes (LKB - Lhomond), Stefan Kuhr (LKB - Lhomond), Michel
Brune (LKB - Lhomond), Jean-Michel Raimond (LKB - Lhomond), Serge Haroche
(LKB - Lhomond)
Categories: quant-ph
Proxy: ccsd hal-00165431
\\
The irreversible evolution of a microscopic system under measurement is a
central feature of quantum theory. From an initial state generally exhibiting
quantum uncertainty in the measured observable, the system is projected into a
state in which this observable becomes precisely known. Its value is random,
with a probability determined by the initial system's state. The evolution
induced by measurement (known as 'state collapse') can be progressive,
accumulating the effects of elementary state changes. Here we report the
observation of such a step-by-step collapse by measuring non-destructively the
photon number of a field stored in a cavity. Atoms behaving as microscopic
clocks cross the cavity successively. By measuring the light-induced
alterations of the clock rate, information is progressively extracted, until
the initially uncertain photon number converges to an integer. The suppression
of the photon number spread is demonstrated by correlations between repeated
measurements. The procedure illustrates all the postulates of quantum
measurement (state collapse, statistical results and repeatability) and should
facilitate studies of non-classical fields trapped in cavities.
\\ ( http://arxiv.org/abs/0707.3880 , 472kb)
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arXiv:0707.3846
Date: Thu, 26 Jul 2007 00:44:52 GMT (17kb)

Title: Quantum statistical measurements of an atom laser beam
Authors: M.K. Olsen, A.S. Bradley, S.A. Haine and J.J. Hope
Categories: physics.atom-ph physics.optics
Journal-ref: Nuclear Physics A, 790, 733c (2007)
\\
We describe a scheme, operating in a manner analogous to a reversed Raman
output coupler, for measuring the phase-sensitive quadrature statistics of an
atom laser beam. This scheme allows for the transferral of the atomic field
statistics to an optical field, for which the quantum statistics may then be
measured using the well-developed technology of optical homodyne measurement.
\\ ( http://arxiv.org/abs/0707.3846 , 17kb)
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The replacements:

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arXiv:0704.1037
replaced with revised version Fri, 20 Jul 2007 19:26:34 GMT (590kb)

Title: Controlled collisions of a single atom and ion guided by movable
trapping potentials
Authors: Z. Idziaszek, T. Calarco, P. Zoller
Categories: quant-ph
\\ ( http://arxiv.org/abs/0704.1037 , 590kb)
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arXiv:0704.2757
replaced with revised version Fri, 20 Jul 2007 14:29:47 GMT (257kb)

Title: Polaron Physics in Optical Lattices
Authors: Martin Bruderer, Alexander Klein, Stephen R. Clark, and Dieter Jaksch
Categories: quant-ph
Journal-ref: Phys. Rev. A 76, 011605(R) (2007)
DOI: 10.1103/PhysRevA.76.011605
\\ ( http://arxiv.org/abs/0704.2757 , 257kb)
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arXiv:cond-mat/0612261
replaced with revised version Sun, 22 Jul 2007 11:32:42 GMT (310kb)

Title: Controllable diffusion of cold atoms in a harmonically driven and tilted
optical lattice: Decoherence by spontaneous emission
Authors: Navinder Singh
Categories: cond-mat.stat-mech
\\ ( http://arxiv.org/abs/cond-mat/0612261 , 310kb)
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arXiv:0707.0870
replaced with revised version Sat, 21 Jul 2007 13:41:06 GMT (1000kb)

Title: Two-Dimensional Dynamics of Ultracold Atoms in Optical Lattices
Authors: Michiel Snoek and Walter Hofstetter
Categories: cond-mat.other
\\ ( http://arxiv.org/abs/0707.0870 , 1000kb)
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arXiv:0707.1538
replaced with revised version Mon, 23 Jul 2007 00:58:10 GMT (9kb)

Title: Transition temperature of the homogeneous, dilute and weakly interacting
Bose gas in D-dimensions
Authors: Sang-Hoon Kim
Categories: cond-mat.stat-mech
\\ ( http://arxiv.org/abs/0707.1538 , 9kb)
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arXiv:0704.0386
replaced with revised version Wed, 25 Jul 2007 09:31:29 GMT (17kb)

Title: Quantum non-local effects with Bose-Einstein condensates
Authors: Franck Lalo\"e (LKB - Lhomond), William J. Mullin
Categories: quant-ph cond-mat.other
Comments: second version submitted to PRL, including changes suggested by
referees
\\ ( http://arxiv.org/abs/0704.0386 , 17kb)
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\\
arXiv:cond-mat/0612664
replaced with revised version Thu, 26 Jul 2007 12:56:43 GMT (251kb)

Title: Vortex quantum creation and winding number scaling in a quenched spinor
Bose gas
Authors: Michael Uhlmann, Ralf Sch\"utzhold and Uwe R. Fischer
Categories: cond-mat.other
Comments: 4 pages of RevTex4, 2 figures; to appear in Physical Review Letters
\\ ( http://arxiv.org/abs/cond-mat/0612664 , 251kb)
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Till next time (whenever that is!)
Matt.

--
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University of Queensland,     ph   : +61 7 334 69824
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Australia.                    http://www.physics.uq.edu.au/people/mdavis/
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Received on Tue Jul 31 2007 - 17:06:39 EST

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