The magnetotransport of a high-mobility two-dimensional electron gas coupled to a hovering split-ring resonator with controllable distance is studied in the quantum Hall regime. The measurements reveal an enhancement by more than a factor 2 of the quantum Hall energy gaps at the fractional filling factors 4/3, 5/3, and 7/5, alongside a concurrent reduction in exchange splitting at odd integer filling factors. Theoretically, we show the strength of both effects to be quantitatively compatible with the emergence of an effective electron-electron long-range attractive interaction mediated by the exchange of virtual cavity photons in the presence of significant spatial gradients of the cavity electric vacuum fields. These results unveil a compelling interplay between cavity quantum electrodynamics and electronic correlations in two-dimensional systems, with profound implications for the manipulation and control of quantum phases in 2D materials.
@article{arxiv.2405.18362,
title = {Enhanced fractional quantum Hall gaps in a two-dimensional electron gas coupled to a hovering split-ring resonator},
author = {Josefine Enkner and Lorenzo Graziotto and Dalin Boriçi and Felice Appugliese and Christian Reichl and Giacomo Scalari and Nicolas Regnault and Werner Wegscheider and Cristiano Ciuti and Jérôme Faist},
journal= {arXiv preprint arXiv:2405.18362},
year = {2025}
}