Optical probing of a two-dimensional electron system in a microcavity: Quantum Hall Polaritons

Elementary excitations of a two-dimensional electron system (2DES) can be described in terms of exciton-polarons, i.e. excitons dressed by Fermi-sea electron-hole pairs due to interactions between excitons and the surrounding electrons [1,2]. An interesting open problem is the modification of this description in the quantum Hall regime, where electrons occupy flat-bands and electron-electron interactions become important. Here, we perform cavity spectroscopy, in the strong-coupling regime, of a two-dimensional electron system embedded in a semiconductor microcavity [3,4]. We observe exciton-polaron-polariton resonances in the regime of integer and fractional quantum Hall effect (FQHE).