Approaching Unit Readout Visibility in a Loss-DiVincenzo Spin Qubit with >99.9% Control Fidelity*

High fidelity gate operations and high visibility readout are required for fault-tolerant implementations of spin-based quantum computing. Typical measurement fidelities for quantum dot and donor spin qubits using coupling to a reservoir for readout range from 68% to 99.5%, with the quantum dot based systems largely limited to <99% [1]. Here we control a single spin qubit in a six-dot linear array using electric dipole spin resonance and achieve single qubit gate fidelities exceeding 99.9%, as verified by randomized benchmarking and gate set tomography [2]. Optimization of the spin-to-charge conversion and electrical charge detection process yields a measurement fidelity exceeding 99% [3,4]. Our results bring the total operation fidelity of a silicon spin qubit above 99%.

[1] Keith et al., New J. Phys. 21, 063011 (2019)

[2] Nielsen et al., Quantum 5, 557 (2021)

[3] Elzerman et al., Nature 430, 431 (2004)

[4] Mills et al. (unpublished)