Instabilities leading to vortex lattice formation in rotating   Bose-Einstein condensates
  We present a comprehensive theoretical study of vortex lattice formation in atomic Bose-Einstein condensates confined by a rotating elliptical trap. We consider rotating solutions of the classical hydrodynamic equations, their response to perturbations, as well as time-dependent simulations. We discriminate three distinct, experimentally testable, regimes of instability: {\em ripple}, {\em interbranch}, and {\em catastrophic}. Under symmetry-breaking perturbations these instabilities lead to lattice formation even at zero temperature. While our results are consistent with previous theoretical and experimental results, they shed new light on lattice formation. 
N. G. Parker, R. M. W. van Bijnen, and A. M. Martin