Characterization of gate fidelities in a Si/SiGe two-qubit device

Various candidate implementations for future quantum computers have been investigated over the past twenty years. Silicon spin qubits show great promise [1] for their long coherence times and integration using semiconductor technology but there have been very few quantitative studies of the fidelities of two-qubit gates. Here we characterize the gate fidelities of a C-Phase gate using randomized benchmarking. For single-qubit gates, we perform randomized benchmarking on each spin by itself and also on both spins simultaneously, to probe cross-talk effects. Furthermore, we developed and experimentally verified a new method called character randomized benchmarking [2,3], which combines the advantages of simultaneous and interleaved randomized benchmarking. With this new method, we characterized the fidelity of a C-Phase gate with tighter bounds than those in the traditional approach.

[1] T.F.Watson, et al, Nature 555, 633-637 (2018).
[2] J.Helsen, et al, arxiv:1806.02048.
[3] X.Xue, et al, manuscript in preparation.