Berlin 2005 – scientific programme

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Q: Quantenoptik und Photonik

Q 50: Quantengase III

Q 50.3: Talk

Tuesday, March 8, 2005, 18:30–18:45, HU Kinosaal

Non-perturbative quantum field theory of far-from-equilibrium dynamics of atomic Bose gases — •Thomas Gasenzer, Jürgen Berges, Michael Schmidt, and Marcos Seco — Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 16, 69120 Heidelberg, Germany

We develop a non-perturbative dynamical quantum field theory for Bose-Einstein condensates which goes beyond the Hartree-Fock-Bogoliubov approximation. The theory is based on action functional techniques, specifically on a 1/N expansion of the Two-Particle-Irreducible Effective Action. It has recently been shown that such approximation methods which correspond to a resummation of graphs to all orders in the coupling constant allow to describe the long-time dynamics including thermalization of strongly interacting many-body systems. We derive the dynamic equations for the mean field and the 2-point correlation functions and examine their long-time validity for systems far from equilibrium by comparing their solution with results from exact calculations.