Quasiparticle dynamics in offset-charge-sensitive transmons

Superconducting qubits are a promising platform to realize a large-scale quantum processor. The presence of nonequilibrium quasiparticles sets an inherent limit on the performance of transmons, a mature superconducting qubit architecture. Intentionally operating a transmon in an offset-charge-sensitive regime allows us to probe quasiparticle tunneling dynamics by detection of charge-parity jumps. Simultaneous parity jumps across multiple qubits can be indicative of quasiparticle-induced spatiotemporally-correlated errors, a significant challenge for quantum error correction protocols. In this work, we use a direct-dispersive charge-parity readout scheme to continuously monitor multiple qubits in an OCS transmon array. We implement filtering and shielding to maximally suppress contributions from photon-assisted tunneling. Further, we characterize the charge-parity lifetimes of devices with additional quasiparticle-tunneling mitigation strategies, such as a superconducting backplane.