Polaron-Polaritons in the Integer and Fractional Quantum Hall Regimes

Sylvain Ravets, Stefan Faelt, Martin Kroner, Werner Wegscheider, Atac Imamoglu

Published 2017-01-04Version 1

Elementary quasi-particles in a two dimensional electron system can be described as exciton-polarons since electron-exciton interactions ensures dressing of excitons by Fermi-sea electron-hole pair excitations. A relevant open question is the modification of this description when the electrons occupy flat-bands and the electron-electron interactions become prominent. Here, we carry out cavity spectroscopy of optical excitations in the strong-coupling regime where exciton-polaron-polariton resonances carry signatures of strongly correlated phases associated with the underlying two dimensional electron system under an external magnetic field. We observe modification of the polariton splitting at different integer and fractional filling factors, demonstrating the modification of electron-exciton interactions by electron spin polarization. Concurrently, we demonstrate that cavity quantum electrodynamics is an invaluable tool to protect the quantum Hall states from light-induced density fluctuations, which allows optically accessing fundamental properties of fragile many-body states. Possible extensions of this work include optical manipulation of anyonic quasi-particles associated with strongly-correlated phases or exploiting the filling factor-dependent splitting to induce strong polariton-polariton interactions.