The most accurate devices for determining time have been atomic clocks for more than 70 years. But that could alter very soon. A global research team is almost finished with a nuclear clock prototype, according to a September 4 announcement from the National Institute of Standards and Technology (NIST). This ground-breaking clock has the potential to improve not only internet and GPS performance but also facilitate the investigation of dark matter and other basic particle physics issues.
Nuclear and atomic clocks both measure time, but the main distinction is how precise they are. Atomic clocks use an atom’s fluctuations to measure time. In particular, a laser light bombardment of a cesium-133 atom causes its electrons to vibrate at a speed of 9,192,631,770 vibrations per second. This is the global standard for accurate coordination in mapping, telecommunications, and other fields. With an error of only 1 second in 300 million years, the NIST caesium fountain clock has been in service since 2014.
However, because nuclear clocks concentrate on the nucleus rather than the complete atom, they provide even more precise timing. Since the nucleus is 100,000 times smaller than an atom, it can vibrate at frequencies significantly higher than those of an atom, resulting in a significant reduction in temporal uncertainty and more cycles per second. Theoretically, this may render the accuracy of the present atomic clocks seem inferior. The objective is to create a clock that is so exact that it wouldn’t lose a second over billions of years, as NIST researcher Jun Ye explains.
Researchers used thorium-229, whose nucleus can be activated with ultraviolet light rather than the high energy X-rays usually used, to get around technological obstacles. Researchers used UV laser beams to suspend thorium nuclei in a crystal and were able to obtain a precision level that was one million times higher than earlier studies. Crucial to the development of nuclear clocks, this milestone also made possible the first-ever frequency coupling between an atomic clock and a nuclear transition.
Though a completely functional nuclear clock is still a ways off, these discoveries represent important progress. Nuclear clocks have the potential to enhance internet availability, increase GPS precision, and facilitate the discovery of new physics, such as the existence of dark matter.