Drude weight, cyclotron resonance, and the Dicke model of graphene cavity QED

TL;DR

This paper explores the realization of the Dicke model in graphene cavity QED, highlighting the importance of a quadratic photon field term that prevents super-radiant phase transition, generated by virtual inter-band transitions.

Contribution

It develops a theoretical framework for graphene cavity cyclotron resonance, showing the quadratic term arises dynamically, differing from the standard Dirac model.

Findings

Quadratic photon field term suppresses super-radiant transition.

Virtual inter-band transitions generate the quadratic term in graphene.

Dicke model behavior is modified in graphene cavity QED.

Abstract

The Dicke model of cavity quantum electrodynamics is approximately realized in condensed matter when the cyclotron transition of a two-dimensional electron gas is nearly resonant with a cavity photon mode. We point out that in the strong coupling limit the Dicke model of cavity cyclotron resonance must be supplemented by a term that is quadratic in the cavity photon field and suppresses the model's transition to a super-radiant state. We develop the theory of graphene cavity cyclotron resonance and show that the quadratic term, which is absent in graphene's low-energy Dirac model Hamiltonian, is in this case dynamically generated by virtual inter-band transitions.