Banner image: A powerful laser shines into a jet of gas, creating a bright plasma and generating ultraviolet light—one component of what could become a fully functioning nuclear clock. (Credit: Chuankun Zhang/JILA)

The world keeps time with the ticks of atomic clocks, but a new type of clock under development—a nuclear clock—could revolutionize how we measure time and probe fundamental physics.

An international research team led by scientists at JILA, a joint institute of the National Institute of Standards and Technology (NIST) and CU Boulder, has demonstrated key elements of a nuclear clock. A nuclear clock is a novel type of quantum timekeeping device that would use signals from the core, or nucleus, of an atom. The team used a specially designed ultraviolet laser to precisely measure the frequency of an energy jump in thorium nuclei embedded in a solid crystal. They also employed an optical frequency comb, which acts like an extremely accurate light ruler, to count the number of ultraviolet wave cycles that create this energy jump. While this laboratory demonstration is not a fully developed nuclear clock, it contains all the key technology for one.

Nuclear clocks could be much more accurate than current atomic clocks, which provide official international time and play major roles in technologies and applications such as GPS and internet synchronization, and in financial transactions. For the general public, this development could ultimately mean even more precise navigation systems (with or without GPS), faster internet speeds, more reliable network connections, and more secure digital communications. 

“Imagine a wristwatch that wouldn't lose a second even if you left it running for billions of years,” said NIST and JILA physicist Jun Ye. “While we're not quite there yet, this research brings us closer to that level of precision.”