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Scientists in Vienna have developed the world’s first self-stabilising nuclear clock, a breakthrough that could lead to more precise timekeeping than today’s advanced atomic clocks.
Researchers at TU Wien in Austria demonstrated that the device could operate steadily for more than 24 hours without relying on a conventional atomic clock to maintain its stability.
The technology uses thorium nuclei, which have an unusual energy transition that can be controlled with laser light. Scientists can use this transition as a highly precise reference for measuring time.
A major breakthrough came in April 2024, when researchers experimentally identified the long-sought nuclear transition. Further work later that year demonstrated how thorium nuclei could serve as a timekeeping reference.
In the new system, a laser shines on a special crystal containing thorium atoms. The nuclei absorb light only when the laser operates at the correct frequency.
If the laser frequency begins to change, the amount of light absorbed by the nuclei decreases. The system detects the change and automatically adjusts the laser, helping the clock maintain a steady rhythm.
The researchers measured the prototype’s performance over 24 hours and achieved a relative precision of around one part in a quadrillion. This corresponds to a timekeeping error of roughly one second over 30 million years.
However, the figure represents an estimate based on the measured precision, not an actual test lasting millions of years. The prototype also remains less precise than the world’s leading optical atomic clocks.
Scientists believe nuclear clocks could eventually surpass existing technologies because atomic nuclei are much less sensitive to certain environmental disturbances than the electrons used in conventional atomic clocks.
The team plans to improve the device by using more powerful lasers and higher-quality thorium crystals.
More precise nuclear clocks could help scientists measure physical quantities with greater accuracy and investigate fundamental properties of nature. The latest achievement marks an important step towards developing a new generation of highly accurate timekeeping devices.