Speaker
Description
Interactions of radioactive radiations with superconducting qubit chips generate dense cascades of electron-hole pairs, whose recombination produces high-energy phonons. These phonons can propagate across the substrate and break Cooper pairs, creating quasiparticles that degrade qubit coherence and induce excess noise and correlated errors across multiple qubits. In this work, we quantitatively investigate noise events and correlated error mechanisms arising from a Radium-224 source placed near to a multi-qubit superconducting chip. We introduce a robust data selection methodology to isolate radiation-induced events from background noise originating from other sources. The rate of radiations induced events are found to scale with source activity and follows an exponential decay consistent with the radioactive decay of the source. We further present the performance of superconducting qubits operated as phonon-mediated detectors, reporting results obtained with a single qubit as well as with configurations combining up to three qubits. Finally, we provide a quantitative characterization of multi-qubit correlated error events and discuss the prospects of this approach for radiation detection applications.