Ultrastrong coupling of high-frequency two-dimensional cyclotron plasma mode with a cavity photon

The microwave transmission of a two-dimensional electron stripe placed on a metallic patch resonator is studied. An ultrastrong coupling of the cyclotron plasmon with a resonator photon mode is identified in the regime, where the plasmon frequency is much greater than the photon frequency. In the zero magnetic field, it is established that the polariton frequency is determined exclusively by the resonator photon frequency and the electron system-resonator overlap factor. Polariton magnetodispersion is studied as a function of electron density, resonator sizes, and stripe dimensions. DOI: 10.1103/PhysRevB.87.045307