Enhanced fractional quantum Hall gaps in a two-dimensional electron gas coupled to a hovering split-ring resonator

Josefine Enkner; Lorenzo Graziotto; Dalin Boriçi; Felice Appugliese; Christian Reichl; Giacomo Scalari; Nicolas Regnault; Werner Wegscheider; Cristiano Ciuti; Jérôme Faist

doi:10.1038/s41586-025-08894-3

arXiv · 2405.18362

Enhanced fractional quantum Hall gaps in a two-dimensional electron gas coupled to a hovering split-ring resonator

Josefine Enkner·Lorenzo Graziotto·Dalin Boriçi·Felice Appugliese·Christian Reichl·Giacomo Scalari·Nicolas Regnault·Werner Wegscheider·Cristiano Ciuti·Jérôme Faist

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Abstract

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.

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Josefine Enkner, Lorenzo Graziotto, Dalin Boriçi, Felice Appugliese, Christian Reichl, Giacomo Scalari, Nicolas Regnault, Werner Wegscheider, Cristiano Ciuti, Jérôme Faist. 2024-05-28. Enhanced fractional quantum Hall gaps in a two-dimensional electron gas coupled to a hovering split-ring resonator. https://doi.org/10.1038/s41586-025-08894-3

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