Published by the Students of Johns Hopkins since 1896
December 22, 2024

Atomic clock accurate to 3% of a nanosecond

By MARK STUCZYNSKI | April 17, 2014

Have you ever been late because of problems with your watch? Good news: the National Institute of Science has your back for the next 300 million years. Their newly developed atomic clock, called NIST-F2, is designed to maintain perfect time with no decay or error. Furthermore, NIST-F2 may have many uses for GPS and other future inventions. While nothing is perfect, this clock is so precise that it only suffers from a 0.03 nanosecond displacement every day. This translates to about 1 second of inaccuracy over 100 million years.

The NIST-F2 will supersede the NIST-F1, which is about a third as accurate as the F2. By comparing the two atomic clocks, research can continuously calibrate and improve the precision of both clocks. While you may not need this degree of accuracy to get to class on time, such a high degree of accuracy is necessary for the function of many systems, including electrical grids, global telecommunications and GPS devices. Most traditional clocks rely on mechanical balances to calculate the difference between one second and the next, but macro-scale physical clocks are prone to errors that develop over time: Pendulums often swing too far, springs may not wind tightly enough and so on.

In contrast to traditional clocks, atomic clocks operate by detecting atomic vibrations. There is an international standard of time measurement, like the platinum rod standard for a meter. It is defined as a little over nine billion cycles between two energy states in cesium atoms.

Common atomic clocks use extremely cold cesium atoms, which are funneled down a radio wave-firing tube that is tuned to the standard frequency of cycling. Atoms attuned to the frequency resonate and can be detected at the end of the tube. Knowledge of these small, precise resonance movements of the cesium atoms allows for extremely accurate measurements of time. The whole system is based on changes in radiation in the system, which forces the cesium’s electrons to oscillate.

The NIST-F2 uses these atomic clock methods for time keeping. Despite the improvements from F1 to F2, work is already underway on F3 and further models.


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