Singapore scientists create world’s most precise atomic clock

The clock uses a single charged atom of lutetium, a rare-earth element, to measure time with record accuracy, according to findings published in the journal Nature on Sept. 23.

Researchers measured its frequency to 19 decimal places, achieving the lowest uncertainty ever reported for an optical atomic clock. The device is about four times more accurate than the previous record holder, which was based on calcium ions.

"I am confident that what we have now is the most accurate clock in the world," said Murray Barrett, an NUS physicist who led the research.

Atomic clocks measure time using a fixed frequency produced when electrons in atoms move between energy levels. A laser is matched to that frequency, with its rapid oscillations acting as the clock's "ticks," according to SciTech Daily.

The second has been defined using cesium atoms since 1967, with atomic clocks helping power GPS and synchronize communications and transportation networks.

Team of scientists at the National University of Singapore with the world's most accurate atomic clock. Photo courtesy of NUS

Lutetium has an advantage over elements used in other atomic clocks because it is less affected by changes in temperature and magnetic fields, helping the clock remain highly accurate. Barrett compared precise timekeeping to an ultramarathon, with the element at the heart of the clock acting as the runner.

"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.

To confirm its accuracy, the researchers built two lutetium clocks and compared them for 200 hours, producing the most precise atomic-clock comparison ever reported. The clocks are so sensitive they can detect tiny differences in the passage of time between objects just five millimeters apart because of changes in gravity.

Such precision could help scientists measure changes in Earth's gravity and eventually redefine the second. International timekeeping experts are considering replacing the current cesium-based standard with more accurate optical atomic clocks in or after 2030.

The Singapore team now plans to develop a smaller, portable version of the clock.