Physicists at the National University of Singapore (NUS) have built the most accurate atomic clock ever, using lutetium. It could keep time for 300 billion years without losing or gaining a second.
The research, published in Nature on 23 September 2026, was led by Associate Professor Murray Barrett of NUS’s Centre for Quantum Technologies. “I am confident that what we have now is the most accurate clock in the world,” Barrett said.
Precision With Lutetium
The team measured the frequency of their lutetium clock to 19 decimal places, reporting uncertainty of 1 × 10⁻¹⁹. To validate the result, they built two independent clocks and compared their ticking over 200 hours. The two agreed to 5.7 × 10⁻¹⁹, the most precise comparison ever.
Dr Kyle Arnold explained, “Comparing clocks and demonstrating reproducibility is the only way to test a standard.”
The clock uses a single charged lutetium‑176 ion held by electric fields, with its transition matched to a laser at 848 nanometres. Lutetium’s advantage is its insensitivity to temperature and magnetic fields, unlike caesium. Barrett noted, “The lutetium clock would be stable even if you went from Death Valley to the Antarctic plateau.”
The team spent over a decade developing “hyperfine averaging” to define the clock transition with unprecedented precision. They are the only group worldwide using lutetium for timekeeping.
The NUS result improves accuracy fourfold over the previous record of 4.4 × 10⁻¹⁹, achieved in China with a calcium‑40 ion clock. The Singapore clocks reported uncertainties of 1.2 × 10⁻¹⁹ and 1.3 × 10⁻¹⁹.
Impact And Future
Such clocks could transform physics, geodesy, GPS, and even redefine the second by 2030. They can probe whether fundamental constants change over time, detect tiny shifts in Earth’s gravitational field, and improve synchronisation for networks and banking.
The NUS clock is so sensitive it detects gravitational time dilation across millimetres.
Currently, the lutetium clock is a laboratory instrument. The next step is miniaturisation into a portable system for real‑world use. Barrett’s team also hopes to compare results with other leading atomic clocks, though logistical challenges remain. Independent reproduction will be needed before universal acceptance.
Barrett’s group began working with lutetium more than a decade ago, convinced of its potential. Their persistence has now yielded results that could shape the future of global time standards. “In the future, I just don’t see how this clock can be beat,” Barrett said.
For Singapore, the achievement is more than technical. It positions the city‑state at the centre of international efforts to redefine how the world measures time itself.
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