Effects of the next-nearest-neighbor hopping in optical lattices

摘要

Introducing the next-nearest- neighbor hopping t' into the Bose-Hubbard model, we study its effects on the phase diagram, on the ground-state energy, and on the quasiparticle and quasihole dispersion relations of the Mott insulating phase in optical lattices. We have found that a negative value of t' enlarges the Mott-insulating region on the phase diagram, while a positive value of t' acts oppositely. We have also found that the effects of t' are dependent on the dimensionality of optical lattices with its effects largest in three-dimensional optical lattices.