Analytical approach to relaxation dynamics of condensed Bose gases

Research highlights: → Time evolution of perturbations from equilibrium in a condensed Bose gas is studied. → Just below the critical temperature the perturbations vanish algebraically. → Anisotropic perturbations are unstable. → At very low temperature perturbations decay exponentially. - Abstract: The temporal evolution of a perturbation of the equilibrium distribution of a condensed Bose gas is investigated using the kinetic equation which describes collision between condensate and noncondensate atoms. The dynamics is studied in the low momentum limit where an analytical treatment is feasible. Explicit results are given for the behavior at large times in different temperature regimes.