Dynamics of driven atom-molecule condensates

At ultracold temperatures, atoms and molecules can coherently interconvert. Recent experiments have studied this phenomenon with unprecedented detail, observing slowly damped oscillations in an atomic/molecular Bose-Einstein condensate, and how periodically modulating the coupling leads to short-time enhancement of the oscillations. Based on a coherent state variational ansatz, we present a quantitive description of these observations which includes the contributions from excited states. We show that the dominant source of damping is the molecular decay into non-condensed pairs, with a pair kinetic energy that is in resonance with the condensate oscillation frequency. Periodically driving the system enhances the oscillations at short times. However, it also leads to an accelerated decay, rapidly cutting off the initial oscillation growth.