A nuclear clock synchronized to ²²⁹Th.
22 affiliations
- 1State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, China.
- 2Beijing Academy of Quantum Information Sciences, Beijing, China.
- 3State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, China. [email protected].
- 4Beijing Academy of Quantum Information Sciences, Beijing, China. [email protected].
- 5Research Center of Laser Crystal, Advanced Laser and Optoelectronic Functional Materials Department, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai, China.
- 6Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, China.
- 7State Key Laboratory of Functional Crystals and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China.
- 8State Key Laboratory of Thorium Energy, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, China.
- 9International Center for Quantum Materials, School of Physics, Peking University, Beijing, China.
- 10Beijing Key Laboratory of Quantum Devices, Peking University, Beijing, China.
- 11Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing, China.
- 12Division of Time and Frequency Metrology, National Institute of Metrology, Beijing, China.
- 13Hefei National Laboratory, Hefei, China.
- 14State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, China.
- 15National Laboratory of Solid-State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China.
- 16Frontier Science Center for Quantum Information, Beijing, China.
- 17Research Center of Laser Crystal, Advanced Laser and Optoelectronic Functional Materials Department, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai, China. [email protected].
- 18Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, China. [email protected].
- 19State Key Laboratory of Functional Crystals and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China. [email protected].
- 20State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, China. [email protected].
- 21Beijing Academy of Quantum Information Sciences, Beijing, China. [email protected].
- 22Frontier Science Center for Quantum Information, Beijing, China. [email protected].
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.
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BibTeX
@article{huang2026nuclear,
title = {{A nuclear clock synchronized to ²²⁹Th.}},
author = {Beichen Huang and Gaowei Yan and Qi Xiao and Wenhao Bu and Chengchun Zhao and Zhen Zhang and Chao Yan and Zhi-Ang Chen and Peixiong Zhang and Gleb Penyazkov and Zhenhai Zhan and Lingfeng Yan and Yuefei Wang and Lin Li and Shanming Li and Dapeng Jiang and Xiaobo Qian and Xuegang Liu and Qiange He and Taoxiang Sun and Haochen Tian and Bingkun Lu and Ningyuan Ma and Juxian Li and Yanzhang Wu and Qiaorui Gong and Yuxiang Li and Haoyu Shi and Xiangliang Li and Longsheng Ma and Shining Zhu and Yuxiang Mo and Jun Lin and Li You and Yige Lin and Xibo Zhang and Yin Hang and Liangbi Su and Shiqian Ding},
journal = {Nature},
year = {2026},
month = oct,
doi = {10.1038/s41586-026-11122-1},
url = {https://europepmc.org/article/MED/42844468},
note = {CC BY},
}
RIS
TY - JOUR
TI - A nuclear clock synchronized to ²²⁹Th.
AU - Beichen Huang
AU - Gaowei Yan
AU - Qi Xiao
AU - Wenhao Bu
AU - Chengchun Zhao
AU - Zhen Zhang
AU - Chao Yan
AU - Zhi-Ang Chen
AU - Peixiong Zhang
AU - Gleb Penyazkov
AU - Zhenhai Zhan
AU - Lingfeng Yan
AU - Yuefei Wang
AU - Lin Li
AU - Shanming Li
AU - Dapeng Jiang
AU - Xiaobo Qian
AU - Xuegang Liu
AU - Qiange He
AU - Taoxiang Sun
AU - Haochen Tian
AU - Bingkun Lu
AU - Ningyuan Ma
AU - Juxian Li
AU - Yanzhang Wu
AU - Qiaorui Gong
AU - Yuxiang Li
AU - Haoyu Shi
AU - Xiangliang Li
AU - Longsheng Ma
AU - Shining Zhu
AU - Yuxiang Mo
AU - Jun Lin
AU - Li You
AU - Yige Lin
AU - Xibo Zhang
AU - Yin Hang
AU - Liangbi Su
AU - Shiqian Ding
PY - 2026
DA - 2026/10/07
JO - Nature
DO - 10.1038/s41586-026-11122-1
UR - https://europepmc.org/article/MED/42844468
AB - 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.
SN - 0028-0836
SN - 1476-4687
ER -