Hamiltonian Phase Error in Resonantly Driven CNOT Gate Above the Fault-Tolerant Threshold

• Main Authors: Wu, Yi-Hsien, Camenzind, Leon C, Noiri, Akito, Takeda, Kenta, Nakajima, Takashi, Kobayashi, Takashi, Chang, Chien-Yuan, Sammak, Amir, Scappucci, Giordano, Goan, Hsi-Sheng, Tarucha, Seigo
• Format: Journal Article
• Language: English
• Published: 18-07-2023
• Subjects: Physics - Mesoscale and Nanoscale Physics; Physics - Quantum Physics
• DOI: 10.48550/arxiv.2307.09031

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 the gate errors are useful to improve the 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.