Nonperturbative dynamical many-body theory of a Bose-Einstein condensate
Abstract
A dynamical many-body theory is presented which systematically extends beyond mean-field and perturbative quantum-field theoretical procedures. It allows us to study the dynamics of strongly interacting quantum-degenerate atomic gases. The non-perturbative approximation scheme is based on a systematic expansion of the two-particle irreducible effective action in powers of the inverse number of field components. This yields dynamic equations which contain direct scattering, memory and ``off-shell'' effects that are not captured by the Gross-Pitaevskii equation. This is relevant to account for the dynamics of, e.g., strongly interacting quantum gases atoms near a scattering resonance, or of one-dimensional Bose gases in the Tonks-Girardeau regime. We apply the theory to a homogeneous ultracold Bose gas in one spatial dimension. Considering the time evolution of an initial state far from equilibrium we show that it quickly evolves to a non-equilibrium quasistationary state and discuss the possibility to attribute an effective temperature to it. The approach to thermal equilibrium is found to be extremely slow.
Cite
@article{arxiv.cond-mat/0507480,
title = {Nonperturbative dynamical many-body theory of a Bose-Einstein condensate},
author = {Thomas Gasenzer and Juergen Berges and Michael G. Schmidt and Marcos Seco},
journal= {arXiv preprint arXiv:cond-mat/0507480},
year = {2010}
}
Comments
21 pages RevTeX, 12 figures