Mesoscopic Klein-Schwinger effect in graphene

TL;DR

This paper demonstrates a mesoscopic analog of the Schwinger effect in graphene, showing how strong electric fields induce electron-hole pair creation, advancing understanding of quantum electrodynamics phenomena in solid-state systems.

Contribution

It introduces a novel mesoscopic Schwinger effect in graphene and provides experimental evidence of electron-hole pair creation via transport measurements.

Findings

Universal 1D-Schwinger conductance observed at pinchoff

Strong electric fields induce electron-hole pair creation

Transition to ohmic Zener regime at twice the pinchoff voltage

Abstract

Strong electric field annihilation by particle-antiparticle pair creation, also known as the Schwinger effect, is a non-perturbative prediction of quantum electrodynamics. Its experimental demonstration remains elusive, as threshold electric fields are extremely strong and beyond current reach. Here, we propose a mesoscopic variant of the Schwinger effect in graphene, which hosts Dirac fermions with an approximate electron-hole symmetry. Using transport measurements, we report on universal 1d-Schwinger conductance at the pinchoff of ballistic graphene transistors. Strong pinchoff electric fields are concentrated within approximately 1 $\mu$m of the transistor's drain, and induce Schwinger electron-hole pair creation at saturation. This effect precedes a collective instability toward an ohmic Zener regime, which is rejected at twice the pinchoff voltage in long devices. These observations advance our understanding of current saturation limits in ballistic graphene and provide a direction for further quantum electrodynamic experiments in the laboratory.