Scientific teams working separately in Vienna and Beijing have developed the world’s first two operating nuclear clocks in what they are calling an important advance in timekeeping that promises wide-ranging practical applications and offers a new tool to investigate fundamental physics. The two devices represent the next generation of atomic clocks, the ultra-accurate timekeeping machines first created in 1949. The two research teams, describing their achievements on Wednesday in scientific papers published in the journal Nature, said nuclear clocks have the potential to outperform the best conventional atomic clocks but do not do so yet.
They are called nuclear clocks not because they are powered by nuclear fusion or fission, as a layman might surmise, but because time is calculated by monitoring how light — a high-powered laser — interacts with the nucleus of an atom. The nuclear clocks both are based on a form, or isotope, of the element thorium, called thorium-229, trapped in solid-state calcium fluoride crystals.
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