Acknowledgements This work is supported in part by the National Natural Science
Foundation of China (61851404), the Beijing Municipal Science and Technology Project
(Z191100007519008), the National Key R&D Program of China (2016YFA0201801), the
Huawei Project (YBN2019075015) and the National Young Thousand Talents Plan.
Author contributions P.Y., H.W. and B.G. conceived and designed the experiments. P.Y. set
up the hardware platform and conducted the experiments. Q.Z. performed the simulation
work. W.Z. benchmarked the system performance. All authors discussed the results. P.Y.,
H.W., B.G., J.T. and J.J.Y. contributed to the writing and editing of the manuscript. H.W. and
H.Q. supervised the project.
Competing interests The authors declare no competing interests.Additional information
Supplementary information is available for this paper at https://doi.org/10.1038/s41586-020-
1942-4.
Correspondence and requests for materials should be addressed to H.W.
Peer review information Nature thanks Darsen Lu and the other, anonymous, reviewer(s) for
their contribution to the peer review of this work.
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