Chinese Scientists Develop Nuclear Optical Clock

Chinese scientists have developed a nuclear optical clock using thorium-229, a technology that could eventually improve the precision of timekeeping beyond existing atomic clocks.

A team led by researchers at Beijing's Tsinghua University used a self-developed 148-nanometer continuous-wave vacuum-ultraviolet laser to drive energy-level transitions inside thorium-229 nuclei.

Unlike conventional atomic clocks, which measure transitions between energy states of electrons, nuclear clocks use transitions within the atomic nucleus. The researchers said their system achieved timekeeping stability nearly an order of magnitude better than that reported by a European team at the same stage of development.

The work was published online on October 7 in Nature, which publishes the finest peer-reviewed research. Scientists in Austria have separately developed a thorium-229 nuclear clock, with the two research teams reporting their results in the journal at the same time.

Atomic nuclei are less susceptible to external electromagnetic disturbances than electrons, giving nuclear clocks the potential to provide highly stable frequency standards. Possible applications include satellite navigation, telecommunications, precision measurement and deep-space exploration, where highly accurate timing and synchronization are required.