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Superfluidité et localisation quantique dans les condensats de Bose-Einstein unidimensionnels

Abstract : This thesis presents a theoretical study of the transport properties of a Bose-Einstein condensate in the presence of disorder. Phase coherence, disorder and interactions lead to a non-trivial competition between superfluidity and Anderson localization. In a first stage, we have studied an experimentally relevant transport situation, namely the dipole oscillations of a condensate in the presence of impurities. The disorder-induced damping has been found to be disconnected to localization effects, and has been explained in terms of the radiation of excitations. This predicted general scenario has recently been confirmed by several experiments. In a second stage, we have studied the superfluid critical velocity of an atom laser moving through a disordered region. An explicit connection between this problem and extreme-value statistics has been established, and it has allowed us to calculate the whole probability distribution of the critical velocity. This distribution is in agreement with numerical simulations. Moreover, we have shown that Anderson localization is only observable for a given set of parameters. Hence, the localization length is affected by interactions and correlations. Finally, we have considered the localization induced by a bichromatic potential and explained it in a semi-classical framework. We have thus pointed out an essential difference between this kind of localization and the one induced by real disorder.
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https://tel.archives-ouvertes.fr/tel-00508419
Contributor : Mathias Albert <>
Submitted on : Tuesday, August 3, 2010 - 4:23:47 PM
Last modification on : Wednesday, September 16, 2020 - 4:04:41 PM
Long-term archiving on: : Tuesday, October 23, 2012 - 12:00:10 PM

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  • HAL Id : tel-00508419, version 1

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Mathias Albert. Superfluidité et localisation quantique dans les condensats de Bose-Einstein unidimensionnels. Physique mathématique [math-ph]. Université Paris Sud - Paris XI, 2009. Français. ⟨tel-00508419⟩

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