Graphene under bichromatic driving: commensurability and spatio-temporal symmetries★
Instituto de Ciencia de Materiales de Madrid, CSIC,
a e-mail: email@example.com
Received in final form: 3 December 2019
Published online: 3 February 2020
We study the non-linear current response of a Dirac model that is coupled to two time-periodic electro-magnetic fields with different frequencies. We distinguish between incommensurable and commensurable frequencies, the latter characterized by Ω2 = (p∕q)Ω1 with co-prime integers p and q. Coupling the (effective) two-level system to a dissipative bath ensures a well-defined long-time solution for the reduced density operator and, thus, the current. We then analyze the spatio-temporal symmetries that force certain current components to vanish and close with conclusions for directed average currents.
© EDP Sciences / Società Italiana di Fisica / Springer-Verlag GmbH Germany, part of Springer Nature, 2020