Physicists in Singapore have unveiled the world’s most accurate atomic clock, a record-breaking device built at the Centre for Quantum Technologies (CQT) at the National University of Singapore (NUS) that would take roughly 260 billion years to lose a single second. Published in September in the journal Nature, the device measures an atomic transition frequency to 19 decimal places with an uncertainty of just one part in 10 quintillion, surpassing previous record-holders developed in China and the United States.
Singapore Surpasses Global Rivals in Timekeeping Precision
The new device edges out the previous global leader—a calcium-ion clock developed by scientists at the Chinese Academy of Sciences in Wuhan—by roughly four times in accuracy. It also surpasses an aluminium-ion clock unveiled by the US National Institute of Standards and Technology. The instrument relies on a single electrically charged ion of lutetium-176 trapped while researchers tune a laser at an 848-nanometre wavelength.
Team leader Murray Barrett, a CQT principal investigator and associate professor in the NUS Department of Physics, stated in the findings that he is confident the hardware is currently the most precise timekeeper on Earth. To verify the performance, the research group constructed two identical lutetium clocks and compared them for more than 200 hours using correlation spectroscopy. The pair agreed to within an uncertainty of 5.7 parts in 10¹⁹, marking the most precise comparison ever recorded between atomic clocks.
Lutetium Resistance to Environmental Disturbance
Traditional atomic clocks, which have relied on caesium-133 atoms since the International Bureau of Weights and Measures (BIPM) standardized the second in 1968, remain vulnerable to external fluctuations like temperature shifts and magnetic fields. The research team invented a method called hyperfine averaging to define the clock transition, capitalizing on lutetium’s natural resilience. Unlike elements requiring extreme environmental control, lutetium-176 maintains its stability across wide temperature swings, with Barrett noting it would remain accurate even when moving between the extreme heat of Death Valley and the freezing Antarctic plateau.
Optical atomic clocks operate at much higher frequencies than conventional caesium instruments, granting them more oscillations to count over identical intervals. Because international standards bodies are considering replacing the decades-old caesium definition of the second in or after 2030, lutetium has emerged as a leading contender for the future definition due to its superior stability and resistance to external interference.
Ultra-Precise Clocks Test General Relativity and Physical Constants
At an uncertainty level of 5.7 parts in 10¹⁹, the clocks achieve a sensitivity where general relativity becomes directly observable. Albert Einstein’s theory predicts that clocks tick more slowly in stronger gravitational fields.
Local variations in Earth’s gravity are not yet mapped with sufficient precision to separate those geographical fluctuations from minute differences in clock performance. However, these ultra-precise instruments offer researchers a novel tool to investigate whether fundamental physical constants, such as the gravitational constant, remain entirely constant over time.
Miniaturizing the Lutetium Clock for Field Deployment
While the hardware currently operates exclusively as a laboratory-scale experiment, the research team is actively planning its next phase of development. Michael Lee, a PhD student at CQT and joint first author of the study, stated that the next objective is to shrink the system into a transportable format suitable for field measurements of gravity and tests of fundamental physics outside the laboratory.
Future field-deployable units could map subtle variations in Earth’s gravitational field for geophysical surveying and engineering applications. For now, the laboratory prototype remains the benchmark for global chronometry.
Frequently Asked Questions About the Lutetium Atomic Clock
How does a lutetium clock differ from traditional caesium clocks?
Traditional caesium clocks operate using microwave frequencies, with 9.19 billion vibrations of a caesium-133 atom defining a second since 1968. The NUS lutetium clock is an optical atomic clock that uses much higher laser frequencies matched to a single trapped lutetium-176 ion, allowing for significantly more oscillations to be counted and yielding a 19-decimal-place precision.
What temperature range can the lutetium clock withstand without losing accuracy?
Unlike other atomic clock elements that require environmental temperatures to be calibrated within a few thousandths of a degree, the lutetium-176 system maintains its accuracy across external temperature swings of up to 5 degrees, remaining reliable across environments ranging from Death Valley to the Antarctic plateau.
When was the research published and who led the team?
The findings were published on September 23 in the journal Nature. The development was led by Murray Barrett, a principal investigator at the Centre for Quantum Technologies and associate professor in the NUS Department of Physics.
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