Two qubit randomized benchmarking of quantum dot spin qubits

Qubits encoded in the electron spin states of gate-defined quantum dots are promising because of their long coherence time. Recent experiments have realized both single qubit operations with fault-tolerant fidelity [1-2] and two qubit logic gates [3-5]. For single qubit gates, randomized benchmarking has emerged as a popular characterization tool. However, for two-qubit gates it has so far only been applied to a few qubit implementations. This is because, in contrast to more fundamental characterization methods like state tomography of Bell states, two-qubit randomized benchmarking requires sequences of significant numbers of qubit operations to be completed with non-vanishing fidelity. Here, we demonstrate two-qubit randomized benchmarking with an average Clifford gate fidelity of 78.9 %. Our results demonstrate the coherent execution of arbitrary two-qubit algorithms on our device and evidence the capabilities of silicon-based quantum computation.

1. M. Veldhorst et al., Nature Nanotech. 9, 981–985 (2014).
2. J. Yoneda et al., Nature Nanotech 13, 102–106 (2018).
3. M. Veldhorst et al., Nature 526, 410–414 (2015).
4. TF. Watson et al., Nature 555, 633–637 (2018).
5. DM. Zajac et al., Science 359, 439–422 (2018).