Electrostatics-induced breakdown of the integer quantum Hall effect in cavity QED

Abstract

We address the prevailing theoretical explanation of the recently observed breakdown of the integer quantum Hall effect in a two-dimensional electron gas embedded in a metallic split-ring resonator. Within the same single-particle description of quantized Hall conductance, we compare previously proposed vacuum-induced transport modifications against an alternative mechanism that explains this breakdown in terms of non-chiral edge channels arising solely from electrostatic boundary effects. This direct comparison shows that for experimentally relevant parameters, the electrostatic contribution exceeds that of any vacuum-induced conductance modifications by many orders of magnitude and yields characteristic transport signatures and energy scales that align well with experimental observations. This finding sheds new light on this puzzling phenomenon, supporting an electrostatic rather than a vacuum-related interpretation that can be directly tested in experiments.