Supporting Data for "Hamiltonian Phase Error in Resonantly Driven CNOT Gate Above the Fault-Tolerant Threshold"

Supporting data for Wu, YH., Camenzind, L.C., Noiri, A. et al. Hamiltonian phase error in resonantly driven CNOT gate above the fault-tolerant threshold. npj Quantum Inf 10, 8 (2024). https://doi.org/10.1038/s41534-023-00802-9

Abstract:

Because of their long coherence time and compatibility with industrial foundry processes, electron spin qubits are a promising platform for scalable quantum processors. A full-fledged quantum computer will need quantum error correction, which requires high-fidelity quantum gates. Analyzing and mitigating gate errors are useful to improve gate fidelity. Here, we demonstrate a simple yet reliable calibration procedure for a high-fidelity controlled-rotation gate in an exchange-always-on Silicon quantum processor, allowing operation above the fault-tolerance threshold of quantum error correction. We find that the fidelity of our uncalibrated controlled-rotation gate is limited by coherent errors in the form of controlled phases and present a method to measure and correct these phase errors. We then verify the improvement in our gate fidelities by randomized benchmark and gate-set tomography protocols. Finally, we use our phase correction protocol to implement a virtual, high-fidelity, controlled-phase gate.