Modeling Particle Impacts and Quasiparticle Poisoning in Superconducting Qubit Arrays*

Correlated errors in qubit arrays are catastrophic for preserving quantum information. Background radiation incident on superconducting qubit devices can create large bursts of pair-breaking phonons that generate quasiparticles (QPs) in the device layer. These energetic events lead to correlated errors in superconducting qubit arrays. To better understand this process and potential mitigation strategies, we model these events in a Monte-Carlo based simulation package called Geant4 Condensed Matter Physics (G4CMP). We model various device configurations of ground plane and back-side films. From this modeling we compute the normalized QP density as a function of position after an impact in dense superconducting qubit arrays. Using these results, we characterize the spatial and temporal dynamics of the QP poisoning footprint following a particle impact for various device configurations. These results help to inform future superconducting qubit device design.