We show that the dynamics of ultracold atoms in a two-dimensional square optical lattice produced by a bichromatic light-shift potential is described by a generalized Hubbard model with an effective staggered magnetic field. For bosonic atoms, besides the known uniform superfluid and Mott insulating phases, the zero-temperature phase diagram exhibits a novel kind of finite-momentum superfluid phase, characterized by a quantized staggered rotational flux. An extension for fermionic atoms leads to a realization of highly tunable interacting Dirac fermions.
|Reference:||Lih King Lim, C. Morais Smith, and Andreas Hemmerich, PRL 100, 130402 (2008).|
|Lih King Lim, Achilleas Lazarides, Andreas Hemmerich, and C. Morais Smith, arXiv: 0905.1281.|