Experimental characterization of correlated qubit decays in IBM Quantum processors attributable to cosmic rays and background gamma radiation*

Recent reports in the literature have demonstrated that high-energy cosmic ray muons and background gamma radiation can severely impact the performance of superconducting quantum processors. Quasiparticles generated by these events can degrade not only single-qubit coherence times, but can also introduce errors that are strongly correlated across many qubits, or within a single qubit over time. Such correlated errors are a serious challenge for quantum error correction algorithms, making understanding and characterization of these processes imperative. In this talk we use our multiqubit IBM Quantum systems as detectors of incident radiation by monitoring the qubits for correlated decays as well as charge offset jumps.  We characterize the rates at which these events occur and their effect on the coherence of these devices.