{ "abstract": "Atomic clocks have made time and frequency the most precisely measured quantities in physics, progressing from microwave standards that realize the SI second¹ to optical clocks with unprecedented precision². A nuclear clock transfers the frequency reference from an electronic to a nuclear transition and the uniquely low-lying, laser-accessible, isomeric transition in ²²⁹Th currently offers the most practical route to compact, robust timekeeping and sensitive tests of fundamental physics³⁻⁸. Realizing such a clock requires turning spectroscopy of the ²²⁹Th nuclear resonance⁹⁻¹⁷ into a stable discriminator for steering a traceable oscillator. Here we demonstrate a ²²⁹Th nuclear clock by stabilizing a continuous-wave, narrow-linewidth 148.4 nm vacuum-ultraviolet (VUV) laser¹⁸ to a resolved, weakly temperature-sensitive nuclear transition17,19 in ²²⁹Th:CaF₂ crystals²⁰⁻²². A 10-μW VUV source generated by four-wave mixing in cadmium vapour18,23,24 and phototube-based frequency modulation absorption readout provide a fast, high-signal-to-noise nuclear discriminator. The clock reaches a fractional frequency instability of 5×10-13/τ/s for averaging time τ. Clock-transition frequencies measured in two independently fabricated crystals agree at the 10⁻¹³ level and are consistent with previous VUV-comb measurements on other ²²⁹Th:CaF₂ crystals¹⁷. These results establish laser-addressed nuclei as operational clock references and provide a reproducible solid-state platform for compact nuclear clocks, nuclear quantum sensors and precision tests of fundamental physics.", "abstract_shown": true, "affiliations": [ "State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, China.", "Beijing Academy of Quantum Information Sciences, Beijing, China.", "State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, China. eardius@163.com.", "Beijing Academy of Quantum Information Sciences, Beijing, China. eardius@163.com.", "Research Center of Laser Crystal, Advanced Laser and Optoelectronic Functional Materials Department, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai, China.", "Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, China.", "State Key Laboratory of Functional Crystals and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China.", "State Key Laboratory of Thorium Energy, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, China.", "International Center for Quantum Materials, School of Physics, Peking University, Beijing, China.", "Beijing Key Laboratory of Quantum Devices, Peking University, Beijing, China.", "Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing, China.", "Division of Time and Frequency Metrology, National Institute of Metrology, Beijing, China.", "Hefei National Laboratory, Hefei, China.", "State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, China.", "National Laboratory of Solid-State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China.", "Frontier Science Center for Quantum Information, Beijing, China.", "Research Center of Laser Crystal, Advanced Laser and Optoelectronic Functional Materials Department, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai, China. yhang@siom.ac.cn.", "Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, China. yhang@siom.ac.cn.", "State Key Laboratory of Functional Crystals and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China. suliangbi@mail.sic.ac.cn.", "State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, China. dingshq@mail.tsinghua.edu.cn.", "Beijing Academy of Quantum Information Sciences, Beijing, China. dingshq@mail.tsinghua.edu.cn.", "Frontier Science Center for Quantum Information, Beijing, China. dingshq@mail.tsinghua.edu.cn." ], "article_type": "research article", "arxiv": null, "author_total": 39, "authors": [ { "affs": [ 0, 1 ], "name": "Beichen Huang" }, { "affs": [ 0, 1 ], "name": "Gaowei Yan" }, { "affs": [ 0, 1 ], "name": "Qi Xiao" }, { "affs": [ 2, 3 ], "name": "Wenhao Bu", "orcid": "0009-0006-3098-7004" }, { "affs": [ 4, 5 ], "name": "Chengchun Zhao" }, { "affs": [ 6 ], "name": "Zhen Zhang" }, { "affs": [ 7 ], "name": "Chao Yan" }, { "affs": [ 8, 9 ], "name": "Zhi-Ang Chen" }, { "affs": [ 4 ], "name": "Peixiong Zhang" }, { "affs": [ 0 ], "name": "Gleb Penyazkov", "orcid": "0000-0002-5925-6241" }, { "affs": [ 0 ], "name": "Zhenhai Zhan" }, { "affs": [ 0 ], "name": "Lingfeng Yan", "orcid": "0000-0001-8965-2942" }, { "affs": [ 1 ], "name": "Yuefei Wang" }, { "affs": [ 4 ], "name": "Lin Li" }, { "affs": [ 4 ], "name": "Shanming Li" }, { "affs": [ 5 ], "name": "Dapeng Jiang" }, { "affs": [ 6 ], "name": "Xiaobo Qian" }, { "affs": [ 10 ], "name": "Xuegang Liu" }, { "affs": [ 10 ], "name": "Qiange He" }, { "affs": [ 10 ], "name": "Taoxiang Sun" }, { "affs": [ 11, 12 ], "name": "Haochen Tian" }, { "affs": [ 11 ], "name": "Bingkun Lu", "orcid": "0009-0003-8085-4427" }, { "affs": [ 0 ], "name": "Ningyuan Ma" }, { "affs": [ 0 ], "name": "Juxian Li" }, { "affs": [ 0 ], "name": "Yanzhang Wu" }, { "affs": [ 4, 5 ], "name": "Qiaorui Gong" }, { "affs": [ 4, 5 ], "name": "Yuxiang Li" }, { "affs": [ 0 ], "name": "Haoyu Shi" }, { "affs": [ 1 ], "name": "Xiangliang Li", "orcid": "0000-0002-7251-7346" }, { "affs": [ 13 ], "name": "Longsheng Ma" }, { "affs": [ 14 ], "name": "Shining Zhu", "orcid": "0000-0002-3472-6497" }, { "affs": [ 0 ], "name": "Yuxiang Mo", "orcid": "0000-0002-8499-7623" }, { "affs": [ 7 ], "name": "Jun Lin" }, { "affs": [ 0, 1, 12, 15 ], "name": "Li You", "orcid": "0000-0002-3919-4768" }, { "affs": [ 11, 12 ], "name": "Yige Lin" }, { "affs": [ 8, 9, 12 ], "name": "Xibo Zhang" }, { "affs": [ 16, 17 ], "name": "Yin Hang", "orcid": "0000-0001-8687-1779" }, { "affs": [ 18 ], "name": "Liangbi Su", "orcid": "0000-0002-5792-1797" }, { "affs": [ 19, 20, 21 ], "name": "Shiqian Ding", "orcid": "0000-0002-0485-8835" } ], "bibtex": "https://research.draconitic.com/paper/cvvmksrav161s.bib", "cited_by": 3, "doi": "10.1038/s41586-026-11122-1", "fulltext_url": "https://europepmc.org/articles/PMC13686941", "id": "cvvmksrav161s", "issns": [ "0028-0836", "1476-4687" ], "landing_url": "https://europepmc.org/article/MED/42844468", "language": "eng", "licence": "CC-BY", "licence_label": "CC BY", "licence_source": "article", "licence_url": "https://creativecommons.org/licenses/by/4.0/", "metadata_licence": null, "native_subjects": [ [ "openalex", "3107|Advanced Frequency and Time Standards" ] ], "openalex": "W7220831501", "pdf_url": "https://europepmc.org/articles/PMC13686941?pdf=render", "pmcid": "PMC13686941", "pmid": "42844468", "published": "2026-10-07", "publisher": null, "ris": "https://research.draconitic.com/paper/cvvmksrav161s.ris", "sources": [ { "first_seen": "2026-10-30T12:18:02Z", "native_id": "MED:42844468", "source": "europepmc", "url": "https://europepmc.org/article/MED/42844468" } ], "subjects": [ { "field": "physics", "origin": "openalex:3107|Advanced Frequency and Time Standards", "subfield": "amo" } ], "title": "A nuclear clock synchronized to ²²⁹Th.", "title_text": "A nuclear clock synchronized to ²²⁹Th.", "type": "peer-reviewed", "updated_at": "2026-10-30T12:18:02Z", "url": "https://research.draconitic.com/paper/cvvmksrav161s", "venue": "Nature", "versions": [] }