  We consider an atomic Bose-Einstein condensate (BEC) loaded in a biased
double-well trap with tunneling rate $K$ and inter-atomic interaction $U$. The
BEC is prepared such that all $N$ atoms are in the left well. We drive the
system by sweeping the potential difference $\epsilon$ between the two wells.
Depending on the interaction $u=NU/K$, and the sweep rate $\dot{\epsilon}$, we
distinguish three dynamical regimes: adiabatic, diabatic, and sudden, and
consider the occupation statistics of the final state. The analysis goes beyond
mean-field theory and is complemented by a semiclassical picture.
