Simultaneous single-qubit driving of semiconductor spin qubits at the fault-tolerant threshold

TL;DR

This paper demonstrates high-fidelity simultaneous single-qubit control in a semiconductor spin qubit array, achieving fidelities above the fault-tolerance threshold, which is vital for scalable quantum computing.

Contribution

It introduces a novel N-copy randomized benchmarking technique for accurately assessing simultaneous qubit gate fidelities in a 2D array.

Findings

Single-qubit gate fidelity up to 99.992%

Simultaneous two- and four-qubit fidelities of 99.905% and 99.34%

Next-nearest neighbor pairs show high robustness to cross-talk

Abstract

Practical Quantum computing hinges on the ability to control large numbers of qubits with high fidelity. Quantum dots define a promising platform due to their compatibility with semiconductor manufacturing. Moreover, high-fidelity operations above 99.9% have been realized with individual qubits, though their performance has been limited to 98.67% when driving two qubits simultaneously. Here we present single-qubit randomized benchmarking in a two-dimensional array of spin qubits, finding native gate fidelities as high as 99.992(1)%. Furthermore, we benchmark single qubit gate performance while simultaneously driving two and four qubits, utilizing a novel benchmarking technique called N-copy randomized benchmarking, designed for simple experimental implementation and accurate simultaneous gate fidelity estimation. We find two- and four-copy randomized benchmarking fidelities of 99.905(8)% and 99.34(4)% respectively, and that next-nearest neighbour pairs are highly robust to cross-talk errors. These characterizations of single-qubit gate quality are crucial for scaling up quantum information technology.