Only 1 second deviation in 7.2 billion years! Chinese scientists achieve breakthrough

On January 25, the reporter learned from the University of Science and Technology of China that the research team of Pan Jianwei, Chen Yuao, Dai Hanning and others successfully developed a strontium atomic optical lattice clock with a stability and uncertainty of 10,000 seconds better than 5×10-18 (equivalent to an error of no more than one second in billions of years). According to publicly published data, this system is not only the best optical clock with comprehensive indicators in China, but also makes my country the second country to achieve the above comprehensive indicators.

It is understood that based on the previous work, the research team achieved laser cooling of strontium atoms and bound them in a long-lived one-dimensional optical lattice. A beam of ultra-stable laser pre-locked to an ultra-stable cavity was used to explore the clock state transition of strontium atoms and realize the closed-loop operation of the optical clock. Through frequency comparison measurements of two independent sets of strontium atomic optical lattice clocks, the stability of a single set of optical clocks was found to be 4×10-18 at an integration time of 10,000 seconds and 2.1×10-18 at 47,000 seconds. On this basis, the research team also carried out an item-by-item assessment of the system frequency shift factors of the Sr1 optical clock, and finally obtained its system uncertainty of 4×10-18, equivalent to a deviation of only 1 second in 7.2 billion years. The above performance indicators show that the optical clock system has partially met the requirements for the redefinition of "seconds".

According to the researchers, this achievement has laid an important technical foundation for realizing long-distance optical clock comparisons, establishing ultra-high-precision optical frequency standards and global optical clock networks in the future. It is also of great value for building a new generation of global time standards and even providing new methods for gravitational wave detection and dark matter searches.

The relevant results were recently published in the internationally renowned academic journal Metrology.

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Source: Xinhua News Agency

Editor: He Tong