Real-time Monitoring of Neon Film Growth for Electron-on-Neon Qubits

TL;DR

This paper presents a real-time monitoring technique for neon film growth using high-$T_c$ resonators, crucial for developing electron-on-neon qubits in quantum computing.

Contribution

It introduces a novel high-$T_c$ resonator-based method for tracking neon film thickness during solidification, enabling better control for quantum device fabrication.

Findings

Final neon film thickness varies stochastically from a few nm to a few μm.

Increasing resonator power reduces the neon film thickness below 100 nm.

Over 300 experiments demonstrate the method's effectiveness in monitoring neon solidification.

Abstract

Electron-on-neon (eNe) charge states coupled to superconducting circuits are a promising platform for quantum computing. Control over the formation of these charge states requires techniques to track and control the growth of solid Ne films on the circuit surface. We demonstrate a real-time Ne film-growth monitor using high-transition-temperature (high-$T_c$) YBCO microwave resonators. The high $T_c$ enables tracking of the film thickness near Ne's triple temperature and below. Across more than 300 solidification experiments, we find that the final Ne thickness varies stochastically from a few nm to a few $\mu$m for films solidified from the liquid phase. By increasing the driving power in the resonator, we consistently reduce the final thickness to below 100 nm. These results represent an important step toward controlled formation of Ne films for eNe qubits and highlight the broader utility of high-$T_c$ resonators for hybrid quantum systems.