A high-fidelity universal quantum control for electron spin qubits in silicon

Fault-tolerant quantum computers rely on quantum error correction which requires universal gate fidelities above 99%. Electron spin qubits in silicon are a promising platform for a large-scale quantum computer. Recent technological advances make it possible to implement single-qubit gate fidelity above 99.9% [1] and controlled-phase gate fidelity above 99% [2,3] in silicon spin qubits. In this work, we demonstrate a resonantly driven controlled-NOT gate with a fidelity of 99.5%, along with single-qubit gate fidelities of 99.8% [4]. A key for the high-fidelity gates is a fast operation by virtue of a micromagnet-induced gradient field and a tunable two-qubit coupling. We identify the condition of gate speed and coupling strength where we robustly achieve high-fidelity gates. Finally, we realize Deutsch-Jozsa and Grover search algorithms with success rates of 96-97% using our universal gate set, showing a feasibility of high-fidelity quantum processing.



[1] J. Yoneda et al., Nature Nanotechnol. 13, 102-106 (2018).

[2] X. Xue et al., Nature 601, 343-347 (2022)

[3] A. R. Mills et al., Sci. Adv. 8, eabn5130 (2022)

[4] A. Noiri et al., Nature 601, 338-342 (2022).