Radiation-induced quantum Fano-type resonances in the transport of n-p-n graphene-based junctions

We present a theoretical study of quantum resonances in the ballistic transport of graphene-based n-p-n junctions subject to an externally applied electromagnetic field (EF). By making use of the Floquet analysis and the quasiclassical approach we analyze the dynamics of electrons in the presence of time and coordinate dependent potential U(z, t). In the absence of the EF the resonant tunneling results in a set of sharp resonances in the dependence of dc conductance sigma on the gate voltage V-g. In irradiated n-p-n junctions we obtain Fano-type resonances in the dependence of sigma(V-g). This coherent quantum-mechanical phenomenon is due to the interplay of two effects: (1) the resonant tunneling through quasibound states and (2) the quantum-interference effect in the region between the "resonant points," where the resonant absorption (emission) of photons occurs, and junction interfaces.