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Chaos quantique et transition d'Anderson avec des atomes refroidis par laser

Abstract : By submitting a cloud of cold caesium atoms to a periodically pulsed standing wave, we experimentally realized a quantum system presenting a dynamic that is chaotic in the classical limit called the Kicked Rotor. Such a system presents a phenomenon called dynamical localization (DL). DL is the suppression of the classical chaotic energy growth by quantum interferences due to long range coherence in momentum space. After a breaktime, the quantum momentum distribution is frozen to a steady state and the energy is stuck to an asymptotic value.
In the last decade many studies have been done to show the fragility of dynamical localization (for example in presence of decoherence or noise), in one of them, we have shown that a small deviation from a strict periodic driving destroys dynamical localization. We present now an experimental study of this destruction by a perturbation where a second frequency is progressively added in the system. We found that the delocalisation scheme is gradual and corresponds to a diffusive scenario with well-defined scaling laws for the various classical and quantum parameters in sharp contradiction with the common analogy to the two dimensional Anderson model for disordered solids. Using a model with three frequencies in the forcing, we have found a phase transition between a localized state to a diffusive regime, as in the three dimensional Anderson model for disordered solids.
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https://tel.archives-ouvertes.fr/tel-00287564
Contributor : Julien Chabé <>
Submitted on : Thursday, June 12, 2008 - 11:07:45 AM
Last modification on : Wednesday, October 21, 2020 - 3:41:21 AM
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Julien Chabé. Chaos quantique et transition d'Anderson avec des atomes refroidis par laser. Physique Atomique [physics.atom-ph]. Université des Sciences et Technologie de Lille - Lille I, 2007. Français. ⟨tel-00287564⟩

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