- Editors' Suggestion
- Letter
Chiral terahertz photocurrent in quantum point contact–split ring resonator coupled systems in the quantum Hall regime
Phys. Rev. B 111, L121407 – Published 20 March, 2025
DOI: https://doi.org/10.1103/PhysRevB.111.L121407
Abstract
The detection of ultrastrong coherent light-matter interaction by photocurrent measurements was realized recently, which provides new ways for investigating polariton physics and quantum transport in cavity fields. The physical processes underlying this electrical detection method, however, have not yet been fully understood. In particular, the properties and origins of the photocurrent in the ultrastrong coupling regime remain elusive. In this work, we have investigated the terahertz-induced photocurrent in a coupled system of the quantum Hall edge electrons and terahertz photons in a split ring resonator. The energy dispersion of the coupled system was measured by conducting terahertz-induced photocurrent spectroscopy through a quantum point contact (QPC). The dependence of the terahertz photocurrent on the polarities of a source-drain bias voltage and a magnetic field was systematically measured. We have found that the observed photocurrent is chiral in nature, showing that the behavior of the photocurrent is consistent with nonequilibrium edge channel transport due to the generation and relaxation of Landau polaritons in multiple Landau levels. Furthermore, we point out that the QPC serves as an enhancer for the photocurrent signals.
