Figure 1:
A model system for seeing topological order. (a) Geometry of a Haldane-style lattice with two interpenetrating triangular lattices. Atoms in internal state A occupy one sublattice; atoms in internal state B occupy the other sublattice. A laser can induce a complex valued hopping t exp(iϕ) (dashed links, ϕ is the phase of the laser) to form topological order (i.e., a nonzero Chern number) for the lattice. (b) Alba et al.’s prediction of the spin projection along e_{x}, e_{y}, and e_{z} for this system, which can be measured with a time-of-flight experiment. The Chern number can be computed from the spin projections. (Spin projections were calculated by Ian Spielman, assuming t/t_{a}=2 and ϕ=2π/3.)