The Chinese team has developed the highest uncertainty index optically trapped clock.

According to the Precision Measurement Science and Technology Innovation Research Institute of the Chinese Academy of Sciences, the trapped ion physics research team at the institute has successfully developed the second-generation liquid nitrogen low-temperature calcium ion optical clock, with a total system uncertainty of 4.4E-19, equivalent to an error of no more than 1 second in approximately 720 billion years of continuous timing. This is currently the highest uncertainty indicator reported for optical clocks. The related results were recently published in the international journal "Physical Review Letters."