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In this talk, I will discuss mechanisms by which (nonlinear) quantum systems effectively 'thermalize' into long time stationary distributions. Focusing on the paradigmatic example of the Dicke model (a large spin coupled to a boson mode), I will demonstrate how a constructive description of the thermalization process is facilitated by the Glauber Q or Husimi function, for which the evolution equation turns out to be of Fokker-Planck type. The equation describes a competition of classical instabilities and quantum diffusion. By this mechanism the system follows a "quantum smoothened" approach to equilibrium, which avoids the notorious singularities inherent to classical chaotic flows. I will touch upon the relevance of the above picture to recent experiments in cold atom physics.

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Prof. Alexander Altland, University of Cologne
Seminarraum Theoretische Physik
Contact: not specified