Chinese scientists have developed an optical clock with stability and uncertainty both surpassing 10^{-19}, a level achieved by only a handful of top global labs. The achievement, published in Metrologia, could position China to lead efforts in redefining the second.
China has joined the global top-tier timekeeping club with a new optical clock. The clock’s key parameters, stability and uncertainty, both surpassed 10^{-19}, a feat achieved by only a handful of labs worldwide, including the US National Institute of Standards and Technology and Germany’s national standards laboratory, as the team wrote in the journal Metrologia this month. Its precision exceeds the threshold required for redefining the second, potentially “allowing China to play a leading role in the effort”, according to state broadcaster CCTV. “It lays a solid foundation for using optical clocks to test fundamental physics, improve next-generation satellite navigation and build a unified ultra-precise global time standard,” Dai told CCTV on March 7. Optical clocks are the most precise timekeeping devices available. They use lasers to trap atoms such as strontium and rubidium at very low temperatures, and measure time from the frequency of light emitted as their electrons jump between energy levels. The clock may lead to smaller, more stable and portable space-based versions.