Scientists at the Centre for Quantum Technologies (CQT) at the National University of Singapore have developed an atomic clock capable of running for 260 billion years without losing a single second. Published in Nature on September 23, the device uses a single trapped ion of lutetium-176 to achieve an uncertainty of just one part in 10 quintillion.
The Lutetium-176 Breakthrough at the National University of Singapore
The record-breaking timepiece operates by measuring the frequency of atomic transitions to 19 decimal places. This puts the Singapore team ahead of competing devices developed in China and the United States.
The NUS clock achieves roughly four times the accuracy of the previous record holder, a calcium-ion clock built by scientists at the Chinese Academy of Sciences in Wuhan. It also edges out an aluminium-ion clock unveiled by the US National Institute of Standards and Technology.
“I am confident that what we have now is the most accurate clock in the world,” stated team leader Murray Barrett, a CQT principal investigator and associate professor in the NUS Department of Physics.
How Optical Atomic Clocks Measure Time Differently
Unlike traditional cesium-based devices that have anchored international timekeeping since 1968, optical atomic clocks operate at significantly higher frequencies. The International Bureau of Weights and Measures (BIPM) originally defined the second based on 9.19 billion vibrations of a cesium-133 atom. Optical systems push precision much further by tracking atomic states via laser tuning.
The NUS device traps a single electrically charged ion of lutetium-176 while researchers tune a laser at a wavelength of 848 nanometres. Lutetium offers a distinct physical advantage over other elements because its transition frequency is exceptionally resistant to environmental disturbances like magnetic fields and temperature shifts.
“The good properties mean that high accuracy can be achieved even in a wide range of environments,” Barrett explained. He added that the clock would maintain its precision across environments ranging from Death Valley to the Antarctic plateau.
Verifying 19 Decimal Places via Correlation Spectroscopy
To confirm their unprecedented accuracy, the researchers constructed two separate lutetium clocks. They compared the pair for more than 200 hours using correlation spectroscopy.
The two independent systems agreed to within an uncertainty of 5.7 parts in 10¹⁹. Lutetium-based timekeeping could lose or gain less than one second over 300 billion years.
At this extreme scale of sensitivity, fundamental physics enters the equation. Einstein’s theory of general relativity dictates that clocks tick more slowly in stronger gravitational fields.
Next Steps for Miniature Field Deployments
While the lutetium clock currently remains a laboratory-scale apparatus, the research team is already working on structural adaptations. The immediate technical objective is to miniaturize the setup into a transportable system.
“The next step is to take the lab-scale clock and miniaturise it into a transportable system,” said Michael Lee, a PhD student at CQT and joint first author of the study.
Deploying these systems into the field will allow researchers to map subtle variations in Earth’s gravitational field and test whether fundamental constants are truly constant. Meanwhile, international timekeeping bodies are considering optical clocks as candidates for a redefinition of the second in or after 2030.
