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

TL;DR

This study demonstrates that coupling a high-mobility two-dimensional electron gas to a hovering split-ring resonator significantly enhances fractional quantum Hall gaps, revealing a new way to manipulate quantum phases via cavity quantum electrodynamics effects.

Contribution

It provides experimental evidence and theoretical explanation for cavity-induced enhancement of quantum Hall gaps through long-range electron-electron interactions mediated by virtual photons.

Findings

Quantum Hall gaps increased by over a factor of 2 at specific fractional fillings.

Reduction in exchange splitting at odd integer fillings.

Theoretical model shows effective attractive interactions mediated by cavity photons.

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.