In a laboratory at the University of Vienna, physicists have created a prototype of a nuclear clock that, for the first time, is capable of maintaining stability on its own. The device uses transitions in the nucleus of a thorium-229 atom and, according to preliminary estimates, may surpass the precision of the best atomic clocks.
Atomic clocks rely on electron oscillations that are sensitive to external fields and temperature. Nuclear clocks, by contrast, work with transitions inside the nucleus, where particles are shielded from most external influences. This makes them potentially a thousand times more precise.
The main innovation is the self-stabilization mechanism. The scientists built in feedback that automatically corrects the laser exciting the nucleus if the frequency begins to "drift." Imagine a pendulum that tightens its own spring so as not to go off track: that is exactly how the new system works.
Such stability opens the way to new technologies. More precise clocks will improve navigation, network synchronization and the search for gravitational waves. They will help test the fundamental constants of nature and look for signs of new physics beyond the Standard Model.
For now the prototype operates under laboratory conditions, but within just a few years the technology is expected to be transferred to compact chips. Then nuclear clocks could appear in satellites, submarines and even everyday devices where ultimate time precision is required.
The discovery in Vienna shows how the quantum properties of the nucleus are turning from a theoretical idea into a working device. The next step is to verify the record precision under real-world conditions and to search for other nuclei suitable for clocks.
