中国研制出不确定度指标最高光钟，720亿年误差不超过1秒

Group 1 - The core achievement is the development of a second-generation liquid nitrogen-cooled calcium ion optical clock with a total system uncertainty of 4.4E-19, which corresponds to an error of less than 1 second over approximately 72 billion years, marking it as the highest reported uncertainty indicator for optical clocks [1][2] - The research team has been engaged in calcium ion optical clock research for nearly 30 years, previously achieving a clock with an uncertainty of 3E-18, which equates to a deviation of less than 1 second over 10.5 billion years [1][2] - The advancement in the optical clock's uncertainty level signifies that China has entered the international first-tier level in the field of time frequency standards [2] Group 2 - The optical clock system's uncertainty directly influences the accuracy and reliability of future time frequency standards, enhancing sensitivity in testing fundamental physical laws and providing precise tools for exploring new physics beyond the standard model [2] - This achievement will support the redefinition of the international unit of "second" based on optical clocks and provide a solid technical foundation for the development of next-generation gravity measurement and precision navigation technologies [2]