Scientists have found an unexpectedly simple way to advance one of the most precise technologies ever imagined: the nuclear clock.
Using a technique inspired by old-fashioned jewelry making, a UCLA-led research team has discovered how to build the core of a nuclear clock using far less rare material than previously thought possible.
The breakthrough could one day lead to ultra-precise clocks small and affordable enough to be used far beyond research labs.
Last year, the same UCLA team achieved something physicists had been chasing for half a century.
They successfully made the nucleus of radioactive thorium-229 absorb and emit light, much like electrons do in ordinary atomic clocks.
This long-sought nuclear transition is the key to building a nuclear clock, which is expected to be far more stable and accurate than today’s best atomic clocks.
Such clocks could dramatically improve navigation systems and even help scientists test whether the fundamental constants of nature change over time.
The problem was scarcity. Thorium-229 is extremely rare and can only be extracted from weapons-grade uranium. Only about 40 grams exist worldwide.
In earlier experiments, the team had to embed thorium atoms inside specially grown fluoride crystals, a process that took 15 years to perfect and required at least one milligram of thorium per sample.
That may not sound like much, but with such a limited global supply, it posed a serious obstacle.
Now the researchers have found a far simpler solution. Instead of growing fragile crystals, they used electroplating, a technique invented in the early 1800s and still used today to coat jewelry.
By slightly adapting this method, they deposited an extremely thin layer of thorium onto stainless steel. The result achieved the same scientific outcome as the crystals, while using about 1,000 times less thorium.
The key insight was realizing that a long-held assumption was wrong. Scientists believed thorium had to be embedded in a transparent material so laser light could reach the nucleus.
The UCLA team showed that this isn’t necessary. Even in opaque materials like metal, enough light can reach thorium atoms near the surface to excite the nucleus. Instead of emitting light, these excited nuclei release electrons, which can be detected simply by measuring an electrical current.
This approach is not only cheaper and faster, but also far more durable than delicate crystals. It opens the door to compact and robust nuclear clocks that could eventually be deployed in real-world systems.
Nuclear clocks could be especially valuable for navigation without GPS. If satellite signals were disrupted by conflict or solar storms, today’s navigation systems would fail. More accurate clocks could allow precise positioning using only local measurements. They could also help submarines navigate for long periods without surfacing and support future deep-space missions.
Beyond navigation, nuclear clocks may enable new tests of Einstein’s theory of relativity and help establish a stable time standard for future human activity beyond Earth. With this deceptively simple advance, a technology once confined to theory may now be on a practical path forward.
Source: UCLA.
