Vortices in a rotating Bose-Einstein condensate under extreme elongation in a harmonic plus quartic trap

The behaviors of a rapidly rotating Bose-Einstein condensate under extreme elongation in a two-dimensional anisotropic harmonic plus quartic trap are investigated. Due to the quartic trap, the system remains stable at high rotating velocity, Ω≥ω (ω is the radial harmonic trap frequency), and vortex lattices form even in the absence of the repulsive s-wave interaction (g). When g is present, the interplay between g and the quartic trap potential can lead to rich vortex lattice transition states as a function of Ω, to which vortex lattices vanish eventually at some higher Ω.