Hamiltonian phase error in resonantly driven CNOT gate above the fault-tolerant threshold
Yi Hsien Wu (National Taiwan University, RIKEN)
Leon C. Camenzind (RIKEN)
A. Noiri (RIKEN)
K. Takeda (RIKEN)
T. Nakajima (RIKEN)
Takashi Kobayashi (RIKEN)
Chien Yuan Chang (RIKEN)
A. Sammak (TU Delft - BUS/TNO STAFF, TU Delft - QuTech Advanced Research Centre)
Giordano Scappucci (TU Delft - QuTech Advanced Research Centre, TU Delft - QCD/Scappucci Lab, Kavli institute of nanoscience Delft)
Seigo Tarucha (RIKEN)
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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.
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