Story perspectives

Vienna Unveils First Thorium-229 Nuclear Clock, Redefines Time

6/17/2026

Summary

Vienna Builds NuclearClock

Vienna’s Center for Quantum Science and Technology built the first nuclear clock using thorium-229 in calcium fluoride, operating without a vacuum and achieving one part in 10 trillion instability after one day.
A team at Tsinghua University in China independently built a comparable clock.
The Vienna clock found no ultralight dark-matter signal, matched atomic-clock sensitivity, and could enable satellite devices that map gravity to centimeter accuracy and help redefine the second.

Summary

Europe vs China

The breakthroughs by European and Chinese teams underscore an international race in nuclear-clock research.
The European team led by Luca Toscani De Col at the Technical University of Vienna built a nuclear clock that stabilizes a laser and benchmarked it to a ytterbium-ion atomic clock.
The Chinese team headed by Beichen Huang of Tsinghua University operated two thorium-229-doped calcium-fluoride crystals, found identical ticking rates, and posted a June 2026 arXiv preprint.

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Vienna Builds NuclearClock

Vienna’s Center for Quantum Science and Technology built the first nuclear clock using thorium-229 in calcium fluoride, operating without a vacuum and achieving one part in 10 trillion instability after one day.
A team at Tsinghua University in China independently built a comparable clock.
The Vienna clock found no ultralight dark-matter signal, matched atomic-clock sensitivity, and could enable satellite devices that map gravity to centimeter accuracy and help redefine the second.

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