Evaluating radiation impact on transmon qubits in above and underground facilities
2024-05-30 16:27
138 浏览 Superconducting qubits can be sensitive to abrupt energy deposits caused by cosmic rays and ambient radioactivity. Previous
studies have focused on understanding possible correlated effects over time and distance due to cosmic rays. In this study, for the first
time, we directly compare the response of a transmon qubit measured initially at the Fermilab SQMS above-ground facilities and then
at the deep underground Gran Sasso Laboratory (INFN-LNGS, Italy). We observe same average qubit lifetime T1 of roughly 80
microseconds at above and underground facilities. We then apply a fast decay detection protocol and investigate the time structure,
sensitivity and relative rates of triggered events due to radiation versus intrinsic noise, comparing above and underground performance
of several high-coherence qubits. Using gamma sources of variable activity we calibrate the response of the qubit to different levels of
radiation in an environment with minimal background radiation. Results indicate that qubits respond to a strong gamma source and it
is possible to detect particle impacts. However, when comparing above and underground results, we do not observe a difference in
radiation induced-like events for these sapphire and niobium-based transmon qubits. We conclude that the majority of these events
are not radiation related and to be attributed to other noise sources which by far dominate single qubit errors in modern transmon
qubits.
Article: arXiv:2405.18355
