Core Viewpoint - The NIM-Sr1 strontium atomic optical lattice clock developed by the China National Institute of Metrology has officially been approved to calibrate International Standard Time, marking a significant milestone in China's optical clock research and enhancing its influence in the international time frequency research field [1][2]. Group 1: Technological Advancements - The NIM-Sr1 clock can achieve precision of up to tens of billions to hundreds of billions of years without error, which is a substantial improvement over the cesium atomic clocks that are accurate to only a few hundred million years [1]. - The successful calibration of the NIM-Sr1 clock signifies a transition from "single-core traction" to "three-engine drive" in China's time frequency standard research, indicating a leap in technological capabilities [2]. Group 2: International Standing - The approval of the NIM-Sr1 clock positions China among the top tier globally in the field of international time frequency standards, reflecting its leadership in this critical area of research [2]. - The calibration data released by the International Bureau of Weights and Measures confirms that the NIM-Sr1 clock passed rigorous evaluations by experts, further solidifying China's standing in the international metrology community [2].

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]