Physicists unveil the most accurate atomic clock ever ‪—‬ and it could literally redefine the second

Scientists have created the most accurate atomic clock ever made ‪—‬ and it could literally redefine the second.

Researchers recently unveiled the record-breaking device, which uses the vibration of atoms of an element called lutetium to precisely measure each microsecond. It is accurate up to 19 decimal places — a 41% improvement over the previous record holder. The results were published Sept. 23 in the journal Nature.

To understand the challenge, imagine precise timekeeping as an ultramarathon and the clock’s core elemental isotope as a runner, said study co-author Murray Barrett, a physicist at the National University of Singapore. “Our job is to make sure the runner can go the distance. Lutetium, as it turns out, is a natural born endurance athlete,” he told Live Science in an email.

Unlike previous atomic clocks, the team’s lutetium-176 clock is not very sensitive to external factors, especially magnetic fields and temperature. Whereas other elements might need environmental temperatures calibrated within a few thousandths of a degree, lutetium-176 keeps ticking even with a 5-degree external temperature swing. Barrett’s lab also developed a technique called hyperfine averaging to dull the most important environmental effects, like gravitational fields, leaving very little variation in timekeeping.

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Such a sensitive atomic clock could become the International System of Units’ – a.k.a., the metric system – new gold standard, the team said. The BIPM is expected to redefine the second in 2030 based on modern atomic clock technology. So far, lutetium seems to be the front-runner for accuracy.

The new atomic clock could also help scientists understand something even more basic about the universe: whether the constants at the foundation of physics, such as G, the gravitational constant, are as constant as we think. “There is some speculation that fundamental constants may actually be changing,” Barrett said. “So ultra-precise clocks give us the tools to explore that.”

Arnold, K. J., Lee, M. D. K., Zhao, Q., Qin, Q., Zhang, Z., Jayjong, N., & Barrett, M. D. (2026). Lu+ optical frequency references with accuracy verified at the 19th digit. Nature. https://doi.org/10.1038/s41586-026-11072-8