Electron-on-solid-neon charge qubit noise characterization

We characterized the noise spectrum of the electron-on-solid-neon (eNe) charge qubit with dynamical decoupling methods and long-term Ramsey measurements when qubits are biased on and off their charge sweet spots. Results show that eNe charge qubits experience 1/f-like noise at the 0.1-1 MHz frequency range with power spectral density at 10^-5 μV²/Hz. Long-term qubit frequency drifting shows slow dynamics contributing to low-frequency (10^-3-10^-1 HZ) noise. The measurement results over different qubits reveal the diverse local noise environments for eNe, suggesting the influences of neon surface texture and nearby floating charges on the qubit’s spectral and coherence properties. Moreover, eNe qubits show thermal-resilient coherence performance with > 1 μs T₂^echo up to 300 mK. Temperature-dependent measurements indicate that thermal-induced decay dominates the decrease of energy relaxation and pure-dephase lifetime at temperatures above 100 mK.