Atomic clocks have been the world’s most accurate time-measuring tool for more than seventy years, but their reign may finally be coming to an end. According to one announcement from the National Institute of Standards and Technology (NIST) on September 4, an international research team is closer than ever to completing the first nuclear clock prototype. When it arrives, experts believe its improved accuracy could not only improve everything from GPS and internet speeds to digital security; such a device could also help investigate the nature of dark matter and other fundamental particle physics theories.
At first glance it may not sound like there is much difference between the two clocks, but it’s all about scale. Atomic clocks base their timekeeping on measuring the exact vibrations of individual atoms to indicate a single second. To do this, a powerful laser light is focused on a cesium-133 atom, which then excites its electrons in a phasing between energy levels with exactly 9,192,631,770 vibrations over the span of one second. Networks of atomic clocks across the planet then synchronize their systems through this measurement to provide high-precision coordination for Internet communications, mapping, space launches, and many other applications. As of 2014, the current primary standard in the US – a cesium fountain clock at NIST – is capable of keeping time with an uncertainty of 1 second in 300 million years.
Nuclear clocks, however, would apply these concepts to exponentially finer-tuned parameters. As the name implies, these devices focus on the vibrations of a single nucleus, as opposed to those of the larger atom. Laser light focused on nuclei (100,000 times smaller than the entire atom) require higher frequencies, which also provides more wave cycles per second. This increases the vibrations per second, which then enables greater accuracy. Theoretically, these result in time uncertainties that make 300 million years seem unreliable by comparison.
“Imagine a wristwatch that doesn’t lose a second even if you let it run for billions of years,” NIST and JILA physicist Jun Ye said in the paper on Wednesday announcement. “While we’re not quite there yet, this research brings us closer to that level of precision.”
In general, nuclei need coherent X-rays to make similar phase jumps, but current technology simply cannot produce the energy levels required to do so. To get around this hurdle, researchers turned to thorium-229, whose nucleus shows a smaller jump than any other known atom, while also requiring only lower-energy ultraviolet light for stimulation.
Once thorium nuclei are suspended in a tiny crystal, researchers shined UV laser beams on them at predictable intervals while using a so-called optical frequency comb – described as a “high-precision light ruler” – to count the vibrating “tick” of the protons . and neutrons. The results were a level of accuracy approximately 1 million times higher than previous measurements based on wavelengths. The team also compared their UV frequency with the optical frequency of one of the most accurate strontium-based atomic clocks in the world to create the first “direct frequency link” between a nuclear transition and an atomic block – a “critical step in the development of the nuclear clock”. and integrating it with existing time and attendance systems,” according to NIST.
[Related: The most precise atomic clocks ever are proving Einstein right—again.]
It’s not just the time measurement barriers that are broken in these experiments. The new array also allowed physicists to observe the shape of a thorium nucleus in groundbreaking detail, which the team likens to being able to view individual blades of grass from an airplane.
Although not a fully completed nuclear clock, researchers have demonstrated for the first time the feasibility of the underlying principles. From here, experts can now start designing an actual device to put such tools into practice. When completed, nuclear clocks could one day support faster and more reliable internet connectivity, more accurate mapping systems, and enable major discoveries within the world of physics, such as detecting dark matter or verifying nature’s theoretical constants, all without the necessity of huge particles. accelerators.