Modulated phases of graphene quantum Hall polariton fluids

TL;DR

This paper theoretically investigates how electron-electron interactions induce a modulated phase in graphene quantum Hall polariton fluids, suggesting experimental detection via collective excitation spectra measurements.

Contribution

It reveals that electron-electron interactions cause an instability leading to a modulated phase in graphene quantum Hall polariton fluids, a novel insight into their many-body behavior.

Findings

Electron-electron interactions induce a modulated phase.

The modulated phase causes collective excitation spectra to soften.

Detection is possible through measurements of excitation spectra.

Abstract

There is growing experimental interest in coupling cavity photons to the cyclotron resonance excitations of electron liquids in high-mobility semiconductor quantum wells or graphene sheets. These media offer unique platforms to carry out fundamental studies of exciton-polariton condensation and cavity quantum electrodynamics in a regime in which electron-electron interactions are expected to play a pivotal role. Focusing on graphene, we present a theoretical study of the impact of electron-electron interactions on a quantum Hall polariton fluid, that is a fluid of magneto-excitons resonantly coupled to cavity photons. We show that electron-electron interactions are responsible for an instability of graphene integer quantum Hall polariton fluids towards a modulated phase. We demonstrate that this phase can be detected by measuring the collective excitation spectra, which soften at a characteristic wave vector of the order of the inverse magnetic length.