Phase diffusion in graphene-based Josephson junctions

TL;DR

This paper investigates phase diffusion in graphene-based Josephson junctions with lead contacts, revealing non-zero resistance at higher temperatures and providing insights into electromagnetic environment effects.

Contribution

It is the first to identify phase diffusion as a source of resistance in graphene Josephson junctions and characterizes its dependence on temperature and gate voltage.

Findings

Observation of supercurrent up to ~2 K

Detection of non-zero resistance attributed to phase diffusion

Characterization of electromagnetic environment effects

Abstract

We report on graphene-based Josephson junctions with contacts made from lead. The high transition temperature of this superconductor allows us to observe the supercurrent branch at temperatures up to $\sim 2$ K, at which point we can detect a small, but non-zero, resistance. We attribute this resistance to the phase diffusion mechanism, which has not been yet identified in graphene. By measuring the resistance as a function of temperature and gate voltage, we can further characterize the nature of electromagnetic environment and dissipation in our samples.