Surface-Morphology-Assisted Trapping of Strongly Coupled Electron-on-Neon Charge States

Single electrons confined to a free neon surface and manipulated through the circuit quantum electrodynamics architecture is a promising novel quantum computing platform. Understanding the exact physical nature of the electron-on-neon (eNe) charge states is important for realizing this platform's potential for quantum technologies. We investigate how resonator trench depth and substrate surface properties influence the formation of eNe charge states and their coupling to microwave resonators. Through experimental observation supported by modeling, we find that shallow-depth etching of the resonator features maximizes coupling strength. By comparing the trapping statistics and surface morphology of devices with altered trench roughness, our Letter reveals the role of fabrication-induced surface features in the formation of strongly coupled eNe states.