Check out our new work on the generation of harmonics in graphene, under the action of an artificial gauge field. We study how bending a flake of graphene introduces a pseudomagnetic field, which, in turn, induces Landau levels in the vicinity of the Dirac cones. This drastically changes the nonlinear optical response of graphene, especially for ultrashort impinging pulses. In particular, equally-spaced harmonics at half-integer multiples of the fundamental frequency are appearing, if the impinging pulse is nearly single-cycled.
You can find our preprint here