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Claude Cohen Tannoudji

Prix Nobel en 1997 pour le ralentissement et le piégeage des atomes par la lumière laser.

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Accueil du site > Séminaires > LKB > Dynamics of matter waves in momentum space : effect of disorder and nonlinearity

Dynamics of matter waves in momentum space : effect of disorder and nonlinearity

Séminaire de Nicolas Cherroret

Mercredi 12 mars 2014 de 14h a 15h, en salle 235A au 29 rue d’Ulm 75005 Paris

Abstract

I will discuss recent developments in the field of matter waves subjected to random potentials (disorder), focusing on the dynamics of their momentum distribution at the level of the 2D Gross-Pitaevskii equation (GPE).

To begin with I will forget the nonlinear term in the GPE and discuss only the role of disorder, which has three prominent effects : First an isotropization of most part of the momentum distribution (due multiple scattering), second the rise of an interference peak in the backward direction (« coherent back scattering »), and third, at longer times, the rise of a peak in the forward direction (« coherent forward scattering »).

In the second part of the talk I will comment on the role of the nonlinearity, which typically induces interactions between the various momenta. As time grows this is the cause of a thermalization process, with a distribution characterized by a peak at zero momentum, sitting on top of a smooth background. This suggests a « wave condensation » phenomenon, here observed in the presence of disorder.

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