Distinguishing radiation- and non-radiation-induced correlated errors in superconducting qubits

Spatiotemporally correlated errors in superconducting qubits pose problems for quantum error correction algorithms. Ionizing radiation from cosmic rays and terrestrial sources has been identified as a cause of correlated errors. Various mitigation strategies are being tested, including reducing the sensitivity of qubits to quasiparticles by adjusting the gap across the Josephson junctions within the qubit circuit. In order to identify and study various types of these errors, we developed algorithms to distinguish events characteristic of particle impacts in the substrate from other types of correlated errors. We examined the distinguishing features and sources of radiation- and non-radiation-induced events. We will present results from both standard and gap-engineered devices, to elucidate how gap engineering changes qubit response to different sources of spatiotemporally correlated errors.