Singapore’s atomic clock sets a new accuracy record

Researchers at the National University of Singapore have built an atomic clock with a reported accuracy equivalent to losing less than one second over 260 billion years. Based on the rare-earth metal lutetium, the laboratory device is four times more accurate than the previous best clock.

To check its performance, the team compared two lutetium clocks over 200 hours of measurements. Their ticks agreed to the 19th digit, a result the researchers describe as the most precise clock comparison yet. That agreement provides an important check on their accuracy estimates.

Each clock uses a single electrically charged lutetium atom. A laser is tuned to the frequency that makes one of the atom’s electrons change energy levels. The light’s oscillations then provide the clock’s ticks.

Lutetium is much less sensitive to changes in temperature and magnetic fields than some other materials used in atomic clocks. The device also works at room temperature and uses commercially available laser technology.

The achievement follows more than a decade of work. Such precision could improve measurements of changes in Earth’s gravity and help underpin a future redefinition of the second. The team also hopes to make the clock smaller and eventually use it outside the lab.