▎ 摘　　要

Photon-assisted electron transport in ballistic graphene is analyzed using scattering theory. We show that the presence of an ac signal (applied to a gate electrode in a region of the system) has interesting consequences on electron transport in graphene, where the low energy dynamics is described by the Dirac equation. In particular, such a setup describes a feasible way to probe energy dependent transmission in graphene. This is of substantial interest because the energy dependence of transmission in mesoscopic graphene is the basis of many peculiar transport phenomena proposed in the recent literature. Furthermore, we discuss the relevance of our analysis of ac transport in graphene to the observability of zitterbewegung of electrons that behave as relativistic particles (but with a lower effective speed of light).