Tomographic characterization of leakage in superconducting quantum gates

Leakage out of the computational subspace is a significant problem affecting the performance of superconducting quantum processors. Characterizing these leakage effects and suppressing them with careful calibration is crucial for ensuring reliable qubit operations. In this talk, we present experimental results quantifying leakage in single-qubit transmon gates using gate set tomography (GST) and compare these results with other leakage characterization techniques like leakage randomized benchmarking. We additionally explore some of the control parameters which affect gate-induced leakage and compare the accuracy of qubit and qutrit GST models.

This work is supported by a collaboration between the U.S. DOE and other Agencies. This material is based upon work supported by the U.S. Department of Energy, Office of Science, National Quantum Information Science Research Centers, Quantum Systems Accelerator and the Undersecretary of War for Research and Engineering under Air Force Contract No. FA8702-15-D-0001 or FA8702-25-D-B002. Any opinions, findings, conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the Department of Energy or the Under Secretary of War for Research and Engineering. Sandia National Laboratories is a multiprogram laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525.