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

Quasiparticle (QP) tunneling events are a leading source of decoherence and, crucially, correlated errors in superconducting circuits. Understanding—and ultimately mitigating—these errors calls for real-time detection of these events across single devices. In this work we quantify rates, durations, and temporal correlations, of the background QP tunneling and intermittent burst episodes. We deploy two co-housed detectors based on charge-sensitive transmon qubits coupled to a common waveguide. By continuously probing coherent microwave scattering, we measure the quasiparticle number parity on each qubit island in real time. With improved infrared filtering and magnetic shielding, we resolve background QP tunneling rates at the single hertz-level with temporal resolution of tens of microseconds. Time-tagged coincidence analysis shows that individual parity switches are uncorrelated across devices whereas burst episodes occur about once per minute and are largely correlated. These bursts have a characteristic lifetime of 10 ms and induce a thousand-fold increase in the QP tunneling rate across both devices. These results establish a practical and extensible platform for mapping the spatial structure of QP bursts and benchmarking mitigation strategies, advancing routes to suppress correlated errors in superconducting quantum processors.