title: Modulated phases of graphene quantum Hall polariton fluids.
abstract: There is a 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. Here, 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 is often at a characteristic wave vector of the order of the inverse magnetic length.
authors.affiliation: NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza dei Cavalieri 7, Pisa I-56126, Italy.
authors.forename: Francesco M D
authors.initials: FM
authors.lastname: Pellegrino
authors.affiliation: NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza dei Cavalieri 7, Pisa I-56126, Italy.
authors.forename: Vittorio
authors.initials: V
authors.lastname: Giovannetti
authors.affiliation: Department of Physics, University of Texas at Austin, Austin, Texas 78712-1081, USA.
authors.forename: Allan H
authors.initials: AH
authors.lastname: MacDonald
authors.affiliation: Istituto Italiano di Tecnologia, Graphene Labs, Via Morego 30, Genova I-16163, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Polini