Understanding and mitigating coupler population induced correlated errors

Leakage from single- and two-qubit gates imposes challenges for high-fidelity gate operations beyond the instantaneous loss in fidelity. For any practical use cases of quantum error correction (QEC) on a superconducting quantum processing unit (QPU), it is pivotal to suppress spatially and temporally correlated error sources. In this talk, our focus is on the tunable transmon coupler: We examine experimentally the key mechanisms of residual coupler population induced infidelity in single- and two-qubit gates and characterize the build-up of coupler population in long circuits of repeated quantum gates. Finally, we show that a coupler reset protocol can be used to improve the fidelities of single- and two-qubit gates.