부산대학교 도서관

The far-from-equilibrium dynamics of an ultracold, one-dimensional Bose gas is studied. The focus is set on the comparison between the solutions of fully dynamical evolution equations derived from the two-particle irreducible (2PI) effective action and their corresponding kinetic approximation in the form of Boltzmann-type transport equations. It is shown that during the time evolution of the gas a kinetic description which includes non-Markovian memory effects in a gradient expansion becomes valid. The timescale at which this occurs is shown to exceed significantly the timescale at which the system's evolution enters a near-equilibrium drift period where a fluctuation-dissipation relation is found to hold and which would seem to be predestined for the kinetic approximation. [ABSTRACT FROM AUTHOR]