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| Main Authors: | , , , , , , , , , , , , , , , , , , , |
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| Format: | Preprint |
| Published: |
2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2509.13991 |
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Table of Contents:
- We report a systematic uncertainty of $9.2\times 10^{-19}$ for the USTC Sr1 optical lattice clock, achieving accuracy at the level required for the roadmap of the redefinition of the SI second. A finite-element model with {\it in situ}-validated, spatially-resolved chamber emissivity reduced blackbody radiation shift uncertainty to $6.3\times 10^{-19}$. Concurrently, an externally mounted lattice cavity combined with a larger beam waist suppressed density shifts. Enhanced lattice depth modulation consolidated lattice light shift uncertainty to $6.3\times 10^{-19}$ by enabling simultaneous determination of key polarizabilities and magic wavelength. Magnetic shifts were resolved below $10^{-18}$ via precision characterization of the second-order Zeeman coefficient. Supported by a crystalline-coated ultra-low-expansion cavity-stabilized laser and refined temperature control suppressing BBR fluctuations, the clock also achieves a frequency stability better than $1\times10^{-18}$ at 30,000-s averaging time. These developments collectively establish a new benchmark in USTC Sr1 clock performance and pave the way for high-accuracy applications in metrology and fundamental physics.