Photon-Assisted Process and High-Harmonic Dynamic Localization in   Graphene Nanoribbons
  We used a complete tight-binding band structure of graphene nanoribbon to obtain, for the first time, analytical techniques for observing photon assisted transport, and dynamic localization of electrons in the graphene nanoribbons. When the ribbons are subject to a multi-frequency dc-ac field, photon assisted replicas show up at rather strong drive force. The strong dependence of the photon peaks on ac amplitudes allow for high-harmonic dynamic oscillations at these amplitudes. We identified regions of positive differential conductivity where a nanoelectronic graphene device may be operated as a small signal amplifier. Our research has also reveal another quantum mechanical phenomenon, fractional photon assisted transport, when the stark factor $r > 1$. 
M. Rabiu, S. Y. Mensah, S. S. Abukari
cond-mat.mtrl-sci cond-mat.mes-hall