Frequency ratio measurements at 18-digit accuracy using an optical clock network
Frequency ratio measurements at 18-digit accuracy using an optical clock network
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DOI：
10.1038/s41586-021-03253-4
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发表时间：
2021-03-25
期刊：
影响因子：
64.8
通讯作者：
Zhang, Xiaogang
中科院分区：
文献类型：
--
作者：
Beloy, Kyle;Bodine, Martha I.;Zhang, Xiaogang
原子钟在广泛的技术和实验中至关重要，包括基础物理测试（1）。在光学频率下工作的时钟现在已经证明了10（-18）级的分数稳定性和再现性，比它们的微波前辈高出两个数量级（2）。光学时钟之间的频率比测量是许多利用这种卓越精度的应用的基础。然而，报告的频率比测量的最高精度在十多年中基本保持不变（3-5）。在这里，我们运行一个基于Al-27（+）的光学时钟网络（参考文献10）。(6))，Sr-87（ref. (7))和Yb-171（参考文献）。(8))，并测量其频率比，分数不确定度等于或低于8 × 10（-18）。利用这种精确度，我们得到了超轻玻色子暗物质与标准模型场（9，10）的潜在耦合的改进约束。我们的光学时钟网络不仅利用光纤（11），而且还利用1.5公里的自由空间链路（12，13）。频率比测量的这一进展为未来的移动的、机载和远程光学时钟网络奠定了基础，这些光学时钟将用于测试物理定律（1）、执行相对论大地测量（14）并大大改善国际计时（15）。
Atomic clocks are vital in a wide array of technologies and experiments, including tests of fundamental physics(1). Clocks operating at optical frequencies have now demonstrated fractional stability and reproducibility at the 10(-18) level, two orders of magnitude beyond their microwave predecessors(2). Frequency ratio measurements between optical clocks are the basis for many of the applications that take advantage of this remarkable precision. However, the highest reported accuracy for frequency ratio measurements has remained largely unchanged for more than a decade(3-5). Here we operate a network of optical clocks based on Al-27(+) (ref.(6)), Sr-87 (ref.(7)) and Yb-171 (ref.(8)), and measure their frequency ratios with fractional uncertainties at or below 8 x 10(-18). Exploiting this precision, we derive improved constraints on the potential coupling of ultralight bosonic dark matter to standard model fields(9,10). Our optical clock network utilizes not just optical fibre(11), but also a 1.5-kilometre free-space link(12,13). This advance in frequency ratio measurements lays the groundwork for future networks of mobile, airborne and remote optical clocks that will be used to test physical laws(1), perform relativistic geodesy(14) and substantially improve international timekeeping(15).