High-Fidelity CNOT Gate for Donor Electron Spin Qubits in Silicon

Abstract

Epitaxial atom-based spin qubits in silicon exhibit excellent properties, and benefit from the outstanding scalability of that material platform. As silicon spin-based qubits now start to meet the 99% fault-tolerance threshold, the authors show how the nuclear spins inherent to the local magnetic environment can be engineered as atomic magnets to boost the fidelities of two-qubit logic gates. Modeling indicates that two-qubit CNOT gate fidelities as high as 99.98% are realistic, through silicon purification and careful engineering. This work provides a roadmap for atom qubits in silicon, showing how to optimize two-qubit gates at both the design and measurement stages.