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List of atomic clocks

This is a list of some experimental laboratory atomic clocks worldwide.

Last revised
Jul 20, 2026
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This is a list of some experimental laboratory atomic clocks worldwide.

Name Operation date Type Accuracy Location Image
CS11 1969 Cs 7×10−15
CS21 1985 Cs 1.2×10−14
CS3 1988 Cs
CS4 1992-2005 Cs
CSF11 1999 Cs fountain 4×10−16
CSF21 2009 Cs fountain 2×10−16
FOCS
NPL-CsF2, Yb+ and Sr+ ion clocks, Sr lattice clock, 4 hydrogen masers23
NIST Ion Clock 2025 Charged Al ion with Mg ion 5.5×10−19
NIST-F15 Cs fountain 3.1×10−16
NIST-F27 Cs fountain 1.1×10−16
USNO Alternate Master Clock
WWV
Department of Defense master clock
18 cesium atomic clocks and 4 hydrogen maser clocks Cs, H
Optical lattice clock
NMIJ-F1, NMIJ-F213 Cs fountain 4.7×10−16
Optical clock14 2012 Ca ion
Caesium Beam Atomic Clock1516 Cs
9 Agilent 5071A caesium clocks18 Cs 5×10−13
KRISS-12021 Cs 1×10−14
Caesium atomic clocks22 Cs
Five caesium clocks, one passive hydrogen maser, two active hydrogen masers23 Cs, H
DOST-PAGASA Juan Time24
Caesium clocks, Hydrogen Maser25 Cs
SOC: Space Optical Clock breadboard (Sr lattice clock)26 Sr lattice
Deep Space Atomic Clock27 2019-2021 Hg ion
Caesium atomic clocks28 Cs
References

References

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  20. "Development of Korea's First Primary Frequency Standard, 'KRISS-1'" (PDF). KRISS. Retrieved 2013-03-01.
  21. Lee, Ho Seong; Kwon, Taeg Yong; Park, Sang Eon; Choi, Sang-Kyung; Park, Young-Ho (August 2004). "Research on Cesium Atomic Clocks at the Korea Research Institute of Standards and Science". Journal of the Korean Physical Society. 45 (2): 256–272. Archived from the original on 2016-03-04. Retrieved 2013-03-06.
  22. "About SST". National Metrology Centre. Archived from the original on 17 December 2013. Retrieved 2013-03-01.
  23. "Time and Frequency Metrology". CSIR-National Physical Laboratory. CSIR-National Physical Laboratory. Retrieved 2023-03-25.
  24. "With PST, "Filipino time" is now "on time"". Department of Science and Technology. Retrieved 2014-06-07.
  25. "Time Standard". Indonesian Institute of Sciences. Archived from the original on 2016-01-21. Retrieved 2016-06-22.
  26. "Space Optical Clock". Institut für Experimentalphysik, Heinrich-Heine-Universität Düsseldorf. Retrieved 2017-01-30.
  27. "Deep Space Atomic Clock". NASA's Jet Propulsion Laboratory. NASA. 27 April 2015. Retrieved 2015-10-28.
  28. "Uruchomiono najdokładniejszy zegar atomowy w Polsce. Nie straci nawet sekundy przez 200 mln lat". wyborcza.pl. Retrieved 2018-03-24.