Tsinghua-Led Chinese Team Develops Thorium-229 Nuclear Optical Clock

What changed

A Tsinghua University-led team and other Chinese research groups have developed a nuclear optical clock based on thorium-229. Published in Nature on October 7, the device uses a 148-nanometre vacuum-ultraviolet laser to drive a nuclear transition at roughly 20 quadrillion cycles per second and stabilize the laser’s frequency.

Why it matters

The breakthrough moves precision timing from an atom’s electrons to its nucleus. Because the nucleus is far smaller than the surrounding electron cloud, its “tick” may be less vulnerable to environmental disturbances.

That could eventually make ultra-precise clocks smaller and more useful outside laboratories. Possible applications include navigation, spacecraft positioning, distance measurement in deep-space missions, high-performance time standards and tests of fundamental physics.

The early outlook is promising but conditional: the work still needs to demonstrate its achieved accuracy, stability and operating duration, while practical miniaturization and an actual deployment timetable remain unresolved.