Vortex formation of a Bose-Einstein condensate in a rotating deep   optical lattice
  We study the dynamics of vortex nucleation and lattice formation in a Bose--Einstein condensate in a rotating square optical lattice by numerical simulations of the Gross--Pitaevskii equation. Different dynamical regimes of vortex nucleation are found, depending on the depth and period of the optical lattice. We make an extensive comparison with the experiments by Williams {\it et al.} [Phys. Rev. Lett. {\bf 104}, 050404 (2010)], especially focusing on the issues of the critical rotation frequency for the first vortex nucleation and the vortex number as a function of rotation frequency. 
Akira Kato, Yuki Nakano, Kenichi Kasamatsu, Tetsuo Matsui
cond-mat.quant-gas