466 research outputs found
Collisional effects on the collective laser cooling of trapped bosonic gases
We analyse the effects of atom-atom collisions on collective laser cooling
scheme. We derive a quantum Master equation which describes the laser cooling
in presence of atom-atom collisions in the weak-condensation regime. Using such
equation, we perform Monte Carlo simulations of the population dynamics in one
and three dimensions. We observe that the ground-state laser-induced
condensation is maintained in the presence of collisions. Laser cooling causes
a transition from a Bose-Einstein distribution describing collisionally induced
equilibrium,to a distribution with an effective zero temperature. We analyse
also the effects of atom-atom collisions on the cooling into an excited state
of the trap.Comment: 9 pages, 5 figure
Separability Criteria from Uncertainty Relations
We explain several separability criteria which rely on uncertainty relations.
For the derivation of these criteria uncertainty relations in terms of
variances or entropies can be used. We investigate the strength of the
separability conditions for the case of two qubits and show how they can
improve entanglement witnesses.Comment: 4 pages, 2 figures, contribution for the proceedings of QCMC 2004 in
Glasgo
Disordered quantum gases under control
When attempting to understand the role of disorder in condensed-matter
physics, one faces severe experimental and theoretical difficulties and many
questions are still open. Two of the most challenging ones, which have been
debated for decades, concern the effect of disorder on superconductivity and
quantum magnetism. Recent progress in ultracold atomic gases paves the way
towards realization of versatile quantum simulators which will be useful to
solve these questions. In addition, ultracold gases offer original situations
and viewpoints, which open new perspectives to the field of disordered systems.Comment: text unchanged, submitted on June 2009; Final version on the website
of Nature Physics at
http://www.nature.com/nphys/journal/v6/n2/abs/nphys1507.htm
Quantum mechanics: No more fields
A self-accelerating electronic wave packet can acquire a phase akin to the Aharonov–Bohm effect, but in the
absence of a magnetic field.Peer ReviewedPostprint (published version
Unruh effect for interacting particles with ultracold atoms
The Unruh effect is a quantum relativistic effect where the accelerated
observer perceives the vacuum as a thermal state. Here we propose the
experimental realization of the Unruh effect for interacting ultracold fermions
in optical lattices by a sudden quench resulting in vacuum acceleration with
varying interactions strengths in the real temperature background. We observe
the inversion of statistics for the low lying excitations in the Wightman
function as a result of competition between the spacetime and BCS Bogoliubov
transformations. This paper opens up new perspectives for simulators of quantum
gravity.Comment: close to the published versio
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