Adiabatic quantum pumping in graphene NIS junctions

TL;DR

This paper studies how adiabatic quantum pumping occurs in graphene NIS junctions, showing that superconductivity enhances the pumped current and that there are distinguishable experimental signatures compared to tunneling conductance.

Contribution

It introduces the analysis of adiabatic quantum pumping in graphene NIS junctions, revealing the enhancement of pumped current by superconductivity and phase differences with semiconductor counterparts.

Findings

Superconductivity enhances pumped current by a factor of 4 at resonance.

Resonances exhibit a π/2 phase difference compared to semiconductor NIS junctions.

Distinct experimental signatures differentiate pumped current from tunneling conductance.

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 $\pi/2$ phase difference. We also predict experimentally distinguishable differences between the pumped current and the tunneling conductance in graphene NIS junctions.