Perfect timing as nuclear clock beats Vienna rival

By the Editorial Team · Thursday, October 8, 2026

Researchers in China and Austria have independently advanced nuclear clock technology by developing thorium-229-based prototypes, with China’s version demonstrating six times greater stability than Austria’s. These nuclear clocks, which measure atomic nucleus transitions rather than electronic movements, could greatly surpass current atomic clock precision and open new avenues in fundamental physics and ultra-accurate timekeeping applications.

Researchers in China and Austria have made significant advancements in the development of nuclear clocks, a next-generation timekeeping technology that promises unprecedented accuracy. Recent studies published in the journal Nature reveal that China’s prototype is approximately six times more stable than a comparable device developed by scientists at TU Wien in Vienna. Both nuclear clocks operate by measuring the frequency of thorium-229 nuclei embedded in crystals, a method that differs fundamentally from traditional atomic clocks that rely on electron transitions.

The independent projects, led by Tsinghua University in Beijing and TU Wien in Vienna, represent a global effort to push the boundaries of precision timing. Thorsten Schumm, a member of the European team, described the progress as “fierce but friendly” competition between the two research groups.

The key innovation lies in shifting the clock’s “tick” from electron movements to the nucleus of the atom. According to Ding Shiqian of the Tsinghua team, the nucleus is much smaller and less susceptible to disturbances from external electric and magnetic fields, which could eventually enable nuclear clocks to achieve extreme accuracy beyond current standards. The thorium nucleus’ unique properties, including its ability to be excited by ultraviolet light, make it a particularly suitable candidate for this technology.

Beyond improved precision, nuclear clocks could also serve as powerful tools in fundamental physics. Ding highlighted their potential to detect subtle changes in physical constants or uncover signals from dark matter, which remain elusive phenomena. The Vienna group has already tested their clock in attempts to identify dark matter, albeit without success so far.

Both teams demonstrated that crystals grown independently produced nearly identical timing signals, indicating strong reproducibility. The Tsinghua researchers reported agreement between two separately grown crystals to within three parts in 10 trillion, and their results aligned closely with measurements from Jun Ye’s group at JILA in the United States, which employs differing materials and methods.

Despite these achievements, nuclear clocks are not yet as stable as the best-performing atomic clocks, which have been the cornerstone of precision time measurement for more than 70 years. Atomic clocks underpin technologies such as satellite navigation and define the official standard of the second.

The concept of nuclear clocks dates back to 2003, when physicists Ekkehard Peik and Christian Tamm proposed using the atomic nucleus’ tightly bound structure to minimize external interference. Most nuclei require much higher energy to transition between states than current lasers can provide. Thorium-229 is a rare exception, with its nucleus transition inducible by ultraviolet photons due to a near-perfect balance of nuclear forces.

In their experiments, both teams used ultraviolet lasers tuned to excite the thorium nuclei within solid crystals. The Chinese team generated ultraviolet light by directing lasers through heated cadmium vapor, while the Vienna researchers noted some variation in the timing signal depending on the laser’s path through the crystal.

Both research groups acknowledge that future improvements in crystal quality—ensuring more uniform thorium distribution and fewer defects—will be crucial to refining the clock’s precision and consistency. If successful, nuclear clocks could eventually be miniaturized into robust, compact devices suitable for widespread application beyond specialized laboratories, potentially revolutionizing fields that require precise timing.

This article was reported by synthesizing coverage from multiple independent news outlets to present a balanced, unbiased account. Read about our editorial standards. Spotted an error? Let us know.