NIST Ion Clock Sets New Record for Most Accurate Clock in the World

Summary

(From left to right) Mason Marshall, David Hume, Willa Arthur-Dworschack and Daniel Rodriguez Castillo stand in front of the aluminum ion clock at NIST. With its recent improvements, the clock can pave the way for the campaign to redefine the second as well as explore new ideas in physics. Credit: R. Jacobson/NIST There’s a new record holder for the most accurate clock in the world. Researchers at the National Institute of Standards and Technology (NIST) have improved their atomic clock based on a trapped aluminum ion. Part of the latest wave of optical atomic clocks, it can perform timekeeping with 19 decimal places of accuracy. Optical clocks are typically evaluated on two levels — accuracy (how close a clock comes to measuring the ideal “true” time, also known as systematic uncertainty) and stability (how efficiently a clock can measure time, related to statistical uncertainty). This new record in accuracy comes out of 20 years of continuous improvement of the aluminum ion clock. Beyond its world-best accuracy, 41% greater than the previous record, this new clock is also 2.6 times more stable than any other ion clock. Reaching these levels has meant carefully improving every aspect of the clock, from the laser to the trap and the vacuum chamber.The team published its results in Physical Review Letters.“It’s exciting to work on the most accurate clock ever,” said Mason Marshall, NIST researcher and first author on the paper. “At NIST we get to carry out these long-term plans in precision measurement that can push the field of physics and our understanding of the world around us.” NIST physicist David Hume holds the newly modified ion trap for the aluminum ion clock. By modifying the trap, the aluminum ion and its magnesium ion partner were able to “tick” unperturbed. Credit: R. Jacobson/NIST The aluminum ion makes an exceptionally good clock, with an extremely steady, high-frequency “ticking” rate. Its ticks are more stable than those of cesium, which provides the...