Interaction Effects on Wannier Functions of a Bose-Einstein Condensate in an Optical Lattice and Implications for Bose-Hubbard Model

Liang, Z. X.; Hu, B. B.; Wu, Biao

Interaction Effects on Wannier Functions of a Bose-Einstein Condensate in an Optical Lattice and Implications for Bose-Hubbard Model

Authors

Liang, Z. X.

Hu, B. B.

Wu, Biao

Description

We show that one can properly take into account of the interaction effects and construct a set of orthonormal Wannier functions for a Bose-Einstein condensate in an optical lattice. These interaction-dependent Wannier functions are used to compute the tunneling rate $J$ and the on-site repulsion $U$ in the Bose-Hubbard model. Both parameters are found to be substantially different from ones calculated with the single-particle Wannier functions. Our numerical results of $U$ are found in good agreement with the measured on-site energy in a recent experiment [Campbell {\it et al.} Science {\bf 314}, 281 (2006)].
4 pages, 3 figures