Adiabatic quantum pumping in normal-metal–insulator–superconductor junctions in a monolayer of graphene

Abstract

We investigate adiabatic quantum pumping through a normal-metal--``insulator''--superconductor (NIS) junction in a monolayer of graphene. The pumped current is generated by periodic modulation of two gate voltages, applied to the insulating and superconducting regions, respectively. In the bilinear response regime and in the limit of a thin high insulating barrier, we find that the presence of the superconductor enhances the pumped current per mode by a factor of 4 at resonance. Compared to the pumped current in an analogous semiconductor NIS junction, the resonances have a $\ensuremath{\pi}/2$ phase difference. We also predict experimentally distinguishable differences between the pumped current and the tunneling conductance in graphene NIS junctions.