Speaker
Description
The interaction of ionizing radiation with superconducting qubits can lead to large-scale correlated errors that are problematic, as they cannot be fixed by conventional error correction techniques. These radiation induced upset events have mostly been studied using the natural radiation in the environment and manmade radioactive sources, making it difficult to directly correlate the observed upset event rate to the incident flux of ionizing radiation. To directly measure the probability of observing a radiation induced upset event in superconducting qubits, we performed a controlled irradiation of eight fixed-frequency transmon qubits by ~15 MeV electrons from a pulsed radiofrequency electron linac coupled to the dilution refrigerator. This Controlled Linac Irradiation of Quantum Experiments (CLIQUE) facility allowed precise time correlation between the electrons from the accelerator and the qubit response, simplifying the study of ionizing radiation induced upset events. Furthermore, the electron flux was continuously monitored during the irradiation allowing the direct correlation between the observed qubit upset rate with the incident flux of high-energy electrons. For relaxation errors, the probability of an electron impact to cause a visible upset event was found to be near 100%. For excitation errors, this upset probability was ~50%.