Electron spin qubits in silicon are a promising platform for fault-tolerant quantum computing. Low-frequency noise, including nuclear spin fluctuations and charge noise, is a primary factor limiting gate fidelities. Suppressing this noise is crucial for high-fidelity qubit operations. Here, we report on a two-qubit quantum device in natural silicon with universal qubit control, designed to investigate the upper limits of gate fidelities in a non-purified Si/SiGe quantum dot device. By employing advanced device structures, qubit manipulation techniques, and optimization methods, we have achieved single-qubit gate fidelities exceeding 99% and a two-qubit Controlled-Z (CZ) gate fidelity of 91%. Decoupled CZ gates are used to prepare Bell states with a fidelity of 91%, typically exceeding previously reported values in natural silicon devices. These results underscore that even natural silicon has the potential to achieve high-fidelity gate operations, particularly with further optimization methods to suppress low-frequency noise.
@article{arxiv.2409.09747,
title = {Pursuing high-fidelity control of spin qubits in natural Si/SiGe quantum dot},
author = {Ning Wang and Shao-Min Wang and Run-Ze Zhang and Jia-Min Kang and Wen-Long Lu and Hai-Ou Li and Gang Cao and Bao-Chuan Wang and Guo-Ping Guo},
journal= {arXiv preprint arXiv:2409.09747},
year = {2024}
}