Coupling plasmons in electrons on helium to a superconducting coplanar waveguide resonator

Hybrid quantum systems offer a versatile platform to explore both the fundamental physics and quantum information science applications of single particle and collective quantum systems. In particular, hybrid systems containing superconducting coplanar waveguide resonators are emerging as an ideal tool for investigating the microwave-frequency collective dynamics of low-dimensional electron systems. In this work, we investigate a hybrid system coupling a superconducting coplanar waveguide resonator with electrons on helium. Spectroscopic measurements of the resonator allow us to demonstrate coupling between a plasmonic excitation of the electron-on-helium system and the fundamental mode of the superconducting resonator (ω/2π = 5.42 GHz), with coupling strength g = 30 MHz. Simultaneous transport experiments allow us to characterize the low-frequency response and phase diagram of the electron system. Finally, we discuss how this hybrid system offers a novel platform for microwave cavity optoplasmonic experiments with electrons on helium.