Universal high-fidelity quantum gates for spin-qubits in diamond

TL;DR

This paper presents the design and experimental demonstration of high-fidelity universal quantum gates for a two-qubit system in diamond, achieving fidelities suitable for scalable quantum computing.

Contribution

The authors develop and optimize a complete set of high-fidelity quantum gates for electron and nuclear spins in diamond, advancing scalable quantum processing.

Findings

Single-qubit gate fidelities up to 99.999%

Two-qubit gate fidelity of 99.93%

Gates can be extended to other spin systems

Abstract

Spins associated to solid-state colour centers are a promising platform for investigating quantum computation and quantum networks. Recent experiments have demonstrated multi-qubit quantum processors, optical interconnects, and basic quantum error correction protocols. One of the key open challenges towards larger-scale systems is to realize high-fidelity universal quantum gates. In this work, we design and demonstrate a complete high-fidelity gate set for the two-qubit system formed by the electron and nuclear spin of a nitrogen-vacancy center in diamond. We use gate set tomography (GST) to systematically optimise the gates and demonstrate single-qubit gate fidelities of up to $99.999(1)\%$ and a two-qubit gate fidelity of $99.93(5) \%$. Our gates are designed to decouple unwanted interactions and can be extended to other electron-nuclear spin systems. The high fidelities demonstrated provide new opportunities towards larger-scale quantum processing with colour-center qubits.