A known source of decoherence in superconducting qubits is the presence of broken Cooper pairs, or quasiparticles. These can be generated by high-energy radiation, either present in the environment or purposefully introduced, as in the case of some hybrid quantum devices. Here, we systematically study the properties of a transmon qubit under illumination by focused infrared radiation with various powers, durations, and spatial locations. Despite the high energy of incident photons, our observations agree well with a model of low-energy quasiparticle dynamics dominated by trapping. This technique can be used for understanding and potentially mitigating the effects of high-energy radiation on superconducting circuits with a variety of geometries and materials.
@article{arxiv.2312.05892,
title = {Quasiparticle dynamics in a superconducting qubit irradiated by a localized infrared source},
author = {Rodrigo Benevides and Maxwell Drimmer and Giacomo Bisson and Francesco Adinolfi and Uwe von Lüpke and Hugo Michiel Doeleman and Gianluigi Catelani and Yiwen Chu},
journal= {arXiv preprint arXiv:2312.05892},
year = {2024}
}