Cavity QED of the graphene cyclotron transition

TL;DR

This paper theoretically explores the cavity quantum electrodynamics of graphene's cyclotron transition, revealing potential for ultrastrong coupling and ground state instabilities unique to Dirac fermions.

Contribution

It introduces a theoretical framework for cavity QED in graphene, highlighting the possibility of ultrastrong coupling and predicting ground state instabilities unlike those in traditional semiconductor systems.

Findings

Ultrastrong coupling regime achievable at high Landau level fillings.

Predicted ground state instability similar to Dicke-model phenomena.

Qualitative differences from massive electron systems in semiconductors.

Abstract

We investigate theoretically the cavity quantum electrodynamics of the cyclotron transition for Dirac fermions in graphene. We show that the ultrastrong coupling regime characterized by a vacuum Rabi frequency comparable or even larger than the transition frequency can be obtained for high enough filling factors of the graphene Landau levels. Important qualitative differences occur with respect to the corresponding physics of massive electrons in a semiconductor quantum well. In particular, an instability for the ground state analogous to the one occuring in the Dicke-model is predicted for increasing value of the electron density.