The dynamics of component separation in a binary mixture of   Bose-Einstein condensates
  We present studies of the time-evolution of a two-component system of Bose-Einstein condensates (BEC) in the |F=1, mf=-1> and |2,1> spin states of Rb-87. The two condensates are created with a well-defined relative phase and complete spatial overlap. In subsequent evolution they undergo complex relative motions which tend to preserve the total density profile. the motions quickly damp out, leaving the condensates in a steady state with a nonnegligible (and adjustable) overlap region. 
D.S. Hall, M.R. Matthews, J.R. Ensher, C.E. Wieman, E.A. Cornell