The best timekeepers today.atomic clocks—eliminate the quantum vibrations of an atom, specifically its electrons. But physicists have long dreamed of even better clocks powered by atomic nuclei, which are less sensitive to environmental perturbations. According to new research, that dream could soon come true.
Last week, two independent teams based in Europe and China reported the first set of results from experiments using an atomic nucleus clock based on calcium fluoride crystals containing thorium-229. Both papers, which have not yet been peer-reviewed, are available as a preprint on arXiv. In the European experiment, the researchers compared how well the clock fared against the major atomic clocks involved in the search for dark matter. The Chinese team, for its part, proven the operation of the clock to compare its performance with atomic clocks.
“These results establish a solid-state platform for compact nuclear clocks, nuclear quantum sensors and precision testing of fundamental physics,” the European team wrote in their paper.
Advanced timing
According to a column According to physicists Eric Hudson and Andrei Derevianko, ultra-precise clocks are “more than scientific curiosities,” as they are vital for smooth navigation, communications and international timekeeping. Hudson and Derevianko, of the University of California, Los Angeles, and the University of Nevada, Reno, respectively, contributed to investigation last December that demonstrated the potential of thorium-229 in the clocks of atomic nuclei.
In atomic clocks, scientists stimulate and stimulate an atom’s electrons to push them from one energy level to another. That absorption “occurs at an exquisitely precise frequency,” they explained, adding that these patterns are “established by the laws of physics” and give the world a fairly consistent standard for keeping time.
Meanwhile, a nucleus is 10,000 times smaller than an atom and less prone to perturbations caused by temperature, electric fields and other environmental perturbations, the two wrote; hence physicists’ long-standing interest in the clocks of atomic nuclei.
A concept comes to life
The challenge, then, was to find an atom that scientists could manipulate most effectively. For example, it should respond to the laser that scientists use to activate the “ticks,” so to speak, to tell time. In that sense, thorium-229 was an “exceptionally rare case” in that it has two different states, which scientists can induce by using lasers to excite the nucleus from one state to another, Hudson and Derevianko explained.
The last couple of articles are based on his work, among many others from the last two decades. Importantly, recent demonstrations implement a feedback loop that stabilizes clock operations. This represents an improvement over the European team’s own work since 2024 and 2025.
“This was the last missing step before calling it a real clock,” said Lars von der Wense, a physicist at the Johannes Gutenberg University of Mainz in Germany. Scientific news. With upcoming improvements in laser and crystal technology, nuclear clocks should advance rapidly, added von der Wense, who was not involved in any of the work.
On the frontier of physics
The practical benefits of nuclear clocks aside, researchers believe they could test the fundamental limitations of nature and new physics, according to Hudson and Derevianko. And, in fact, that’s what the European team immediately set out to do with their latest version of a nuclear clock. The second half of their paper describes how well the watch did in assessing the limitations of ultralight dark matter, a hypothetical form of matter that could explain a lot of cosmic mysteries.
Thorsten Schumm, a physicist on the European team at TU Wien in Austria, told Science News that the nuclear clock already outperformed all atomic clocks in certain types of measurements. That said, the technology is still in its early stages, he added. But it looks like nuclear clocks are off to a good start.
