Cavity-enhanced superconductivity via band engineering

TL;DR

This paper demonstrates that coupling a 2D electron gas to a cavity mode can enhance superconductivity, with potential experimental observation via STM and relevance to cold atom systems.

Contribution

It introduces a comprehensive model including all Peierls phase terms, showing cavity-induced superconductivity enhancement beyond naive approaches.

Findings

Superconducting gap increases linearly with cavity coupling strength.

Enhancement observable via STM in 2D materials or Moiré systems.

Relevance extends to cold atom quantum optics setups.

Abstract

We consider a two-dimensional electron gas interacting with a quantized cavity mode. We find that the coupling between the electrons and the photons in the cavity enhances the superconducting gap. Crucially, all terms in the Peierls phase are kept, in contrast to more naive approaches, which may result in spurious superradiant phase transitions. We use a mean-field theory to show that the gap increases approximately linearly with the cavity coupling strength. The effect can be observed locally as an increase in the gap size via scanning tunneling microscopy (STM) measurements for a flake of a 2D material (or for a Moir\'e system where the enhancement is expected to be more pronounced due to a large lattice constant) interacting with a locally-structured electromagnetic field formed by split-ring resonators. Our results are also relevant for quantum optics setups with cold atoms interacting with the cavity mode, where the lattice geometry and system parameters can be tuned in a vast range.