Nonexponential decay of Bose-Einstein condensates: a numerical study based on the complex scaling method

We study the decay dynamics of an interacting Bose-Einstein condensate in the presence of a metastable trapping potential from which the condensate can escape via tunneling through finite barriers. The time-dependent decay process is reproduced by means of the instantaneous decay rates of the condensate at a given population of the quasi-bound state, which are calculated with the method of complex scaling. Both for the case of a double barrier potential as well as for the case of a tilted periodic potential, we find pronounced deviations from a monoexponential decay behaviour which would generally be expected in the absence of the atom-atom interaction.