Strong Confinement and Oscillations in Two-Component Bose-Einstein   Condensates
  We present a new model of BEC dynamics based on strong confinement near the ground state. The model predicts oscillations in a two-component condensate, based on interference of non-spreading wave packets moving within a pair of tilted nearly square potentials. The oscillations are similar to those recently reported for a magnetically trapped $^{87}$Rb condensate, and the model's predictions give good quantitative agreement with the experiments. 
Q-Han Park and J. H. Eberly