‘Nuclear clock’ breakthrough paves the way for super-precise timekeeping

Physicists have demonstrated all the ingredients of a nuclear clock — a device that keeps time by measuring tiny energy shifts inside an atomic nucleus. The breakthrough came from probing the nuclei of a rare isotope with a laser device called a frequency comb. Although the set-up isn’t technically a clock, because it hasn’t been used to measure time, “such impressive results make the development of a nuclear clock seem possible”, says atomic physicist Marianna Safronova. “It’s really one of the most exciting papers in recent times.”