Ultrastrong coupling of the cyclotron transition of a two-dimensional electron gas to a THz metamaterial

摘要

Artificial cavity photon resonators with ultrastrong light-matterinteractions are attracting interest both in semiconductor and superconductingsystems, due to the possibility of manipulating the cavity quantumelectrodynamic ground state with controllable physical properties. We reporthere experiments showing ultrastrong light-matter coupling in a terahertzmetamaterial where the cyclotron transition of a high mobility two-dimensionalelectron gas is coupled to the photonic modes of an array of electronicsplit-ring resonators. We observe a normalized coupling ratio $\frac{\Omega}{\omega_c}=0.58$ betweenthe vacuum Rabi frequency $\Omega$ and the cyclotron frequency $\omega_c$. Oursystem appears to be scalable in frequency and could be brought to themicrowave spectral range with the potential of strongly controlling themagnetotransport properties of a high-mobility 2DEG.