Separate and efficient characterization of SPAM errors in the presence of leakage

Accurate and reliable state preparation and measurement (SPAM) is essential for quantum computation. While characterization procedures such as randomized benchmarking estimate the error contribution from SPAM collectively, separate characterization of state preparation and measurement error is valuable for informing hardware improvements and error mitigation strategies. Existing techniques for separately estimating state preparation and measurement error are limited by 2-qubit gate errors, susceptibility to environmental noise, and failure to account for leakage, which is a leading source of SPAM error in many quantum platforms. To address these challenges, we extend the approach of Ref. [1] to separately characterize state preparation and measurement errors in the presence of leakage. Our approach relies on high-fidelity single-qubit gates and repeated single qubit measurements without reset. We assess the effectiveness of this procedure on a trapped ion quantum computer.