Atomic clock
An atomic clock is a clock that works with atoms, as opposed to most other clocks which are mechanical. The frequency comes from the crossing radiation of electrons. Atomic clocks are currently the most exact clocks of the world. They are also called primary clocks.[1]
Most clocks know the time because they count how many times something moves back and forth. Atomic clocks count how many times an atom wiggles back and forth.
Worldwide, there are over 260 atomic clocks at over 60 different places. All data is collected at the International Bureau of Weights and Measures in Paris, France. The International Atomic Time is calculated there.[2]
The basics were developed by Isidor Isaac Rabi. He was an American physicist at Columbia University. He got the Nobel Prize in Physics in 1944.[3]
Atomic Clock Media
The master atomic clock ensemble at the U.S. Naval Observatory in Washington, D.C., which provides the time standard for the U.S. Department of Defense. The rack mounted units in the background are Microsemi (formerly HP) 5071A caesium beam clocks. The black units in the foreground are Microsemi (formerly Sigma-Tau) MHM-2010 hydrogen maser standards.
Louis Essen (right) and Jack Parry (left) standing next to the world's first caesium-133 atomic clock (1955)
A caesium atomic clock from 1975 (upper unit) and battery backup (lower unit)
A ytterbium lattice clock that uses photons to measure time precisely
The heart of NIST's next-generation miniature atomic clock – ticking at high "optical" frequencies-- is this vapor cell on a chip, shown next to a coffee bean for scale.
Data points representing atomic clocks around the world that define International Atomic Time (TAI)
Simplified block diagram of typical commercial cesium beam frequency reference
A team of United States Air Force airmen carrying a rubidium clock
Hydrogen maser, a maser atomic clock that produces microwave radiation at 1.42 GHz using hydrogen.
Historical accuracy of atomic clocks from NIST
References
- ↑ "The primary clocks" (in Deutsch). Retrieved December 1, 2009.
- ↑ "BIPM". Retrieved December 1, 2009.
- ↑ Fritz von Osterhausen (1999). Callweys Uhrenlexikon. München: Callwey. p. 24. ISBN 978-3-7667-1353-7.
