Speaker
Description
In addition to radiation impacts, superconducting qubit arrays can be subject to correlated quasiparticle poisoning from nonionizing sources that also result in bursts of pair-breaking phonons. We observe elevated correlated and single-qubit poisoning rates in superconducting qubit arrays at the start of a cooldown followed by power-law reductions in time, while the rate of offset charge shifts, a characteristic associated with ionizing impacts, remains constant. In addition, for qubit arrays suspended by wirebonds in their sample package, we observe elevated poisoning due to mechanical impacts from the cryocooler. We discuss possible sources of these phonon-only events, including relaxation of built-up stress in the device thin films, substrates, or packaging, and potential mitigation strategies.
