Characterization of control in a superconducting qutrit using randomized benchmarking

We characterize control of a qutrit implemented in the lowest three energy levels of a capacitively shunted flux-biased superconducting circuit. Randomized benchmarking over the qutrit Clifford group yields an average fidelity of 98.89±0.05%. For a selected subset of the Clifford group, we perform quantum process tomography and observe the behavior of repeated gate sequences. Each qutrit gate is generated using only two-state rotations via a method applicable to any unitary. We find that errors are due primarily to decoherence and have a significant contribution from level shifts. This work demonstrates high-fidelity qutrit control and outlines avenues for future work on the optimal control of superconducting qudits.

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Published in: Physical Review Research
License: https://creativecommons.org/licenses/by/4.0/
See article on publisher's website: https://dx.doi.org/10.1103/physrevresearch.3.l042007