Real-time detection of correlated quasiparticle tunneling events in a multi-qubit superconducting device

Quasiparticle tunneling causes decoherence and correlated errors in superconducting circuits, motivating real-time detection on individual devices. We simultaneously detect quasiparticle tunneling in two co-housed, charge-sensitive transmons coupled to a common waveguide. Background rates are measured at the single-hertz level with microsecond resolution. Individual events are uncorrelated, while burst episodes occur about once per minute, last ~7 ms, are largely correlated across devices, and increase tunneling rates by three orders of magnitude.