Quantum pumping in graphene

TL;DR

This paper demonstrates that graphene quantum pumps utilize evanescent modes, especially at the Dirac point, leading to a universal response under weak driving, which could influence future nanoelectronic device design.

Contribution

It reveals the significant role of evanescent modes in graphene quantum pumps and their impact on transport properties at the Dirac point.

Findings

Evanescent modes dominate pumping at the Dirac point.

Universal response observed under weak driving in short, wide pumps.

Evanescent modes contribute negligibly to normal pumps.

Abstract

We show that graphene-based quantum pumps can tap into evanescent modes, which penetrate deeply into the device as a consequence of Klein tunneling. The evanescent modes dominate pumping at the Dirac point, and give rise to a universal response under weak driving for short and wide pumps, in close analogy to their role for the minimal conductivity in ballistic transport. In contrast, evanescent modes contribute negligibly to normal pumps. Our findings add a new incentive for the exploration of graphene-based nanoelectronic devices.