Strong topological insulator phase in cold-atom systems

With the recent technological advance of creating (electromagnetic) gauge fields for ultracold atoms, the fascinating prospect of realizing novel topological phases in these systems arises. Specifically, we consider spin-1/2 fermions on a square lattice under the influence of various experimentally feasible gauge fields. In two dimensions and if particles with different spin are exposed to magnetic fields in time-reversed directions, the system displays a quantum spin Hall ground state. We then study the influence of hopping into the third direction (2D-3D crossover), and in the three-dimensional system, we are able to identify a strong topological insulator phase. We further elaborate on the influence of the external trapping potential as well as the unambiguous detection of the topological phases.