Engineering Floquet topological phases using elliptically polarized light

We study a two-dimensional topological system driven out of equilibrium by the application of elliptically polarized light. In particular, we analyze the Bernevig-Hughes-Zhang model when it is perturbed using an elliptically polarized light of frequency ω described in general by a vector potential A(t)=(A0xcos(ωt),A0ycos(ωt+φ0)). Even for a fixed value of φ0, we can change the topological character of the system by changing the x and y amplitudes of the drive. We therefore find a rich topological phase diagram as a function of A0x, A0y, and φ0. In each of these phases, the topological invariant given by the Chern number is consistent with the number of spin-polarized states present at the edges of a nanoribbon.