Bose-enhanced relaxation of driven atom-molecule condensates

Motivated by recent experiments we study the interconversion between ultracold atomic and molecular condensates, quantifying the resulting oscillations and their slow decay. We find that near equilibrium the dominant damping source is the decay of condensed molecules into non-condensed pairs, with a pair kinetic energy that is resonant with the frequency of the oscillating atom-molecule interconversions. The decay, however, is non-exponential, as strong population of the resonant pairs leads to Bose enhancement. Introducing an oscillating magnetic field, which periodically modulates the molecular binding energy, enhances the oscillations at short times. However, the resulting enhancement of the pair-production process results in an accelerated decay which rapidly cuts off the initial oscillation growth.