Qubit coherence falls after radiation hits detector arrays

Researchers at Lawrence Livermore National Laboratory have directly linked cosmic radiation to performance degradation in superconducting qubits, observing up to a 30.5% reduction in both energy relaxation (T_1) and phase coherence (T_2) immediately after detecting radiation events. The team built a novel platform that sandwiches a superconducting qubit between two microwave kinetic inductance detector (MKID) arrays, allowing real-time correlation of radiation-induced phonon bursts with qubit decoherence. This work demonstrates that decoherence isn’t random. It’s correlated with events attributed to penetrating muons, challenging assumptions used in most quantum error correction protocols. The platform provides a foundation for developing shielding and refining error-correction algorithms tailored to these correlated noise sources. Measurements reveal a quantifiable link between cosmic radiation and the performance of superconducting qubits, with coherence, both energy relaxation (T₁) and phase coherence (T₂), decreasing by as much as 30.5% immediately after the detection of penetrating muons by microwave kinetic inductance detector (MKID) arrays. This reduction in qubit performance occurs following simultaneous events registered by both MKID arrays, indicating a correlation beyond random decoherence and challenging assumptions within current quantum error correction protocols. The platform’s design uses the sensitivity of MKIDs to quasiparticles generated when radiation…