List of atomic clocks

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

Name Operation date Type Accuracy Location Image
CS1 1969 Cs 7×10−15
CS2 1985 Cs 1.2×10−14
CS3 1988 Cs
CS4 1992-2005 Cs
CSF1 1999 Cs fountain 4×10−16
CSF2 2009 Cs fountain 2×10−16
FOCS
NPL-CsF2, Yb+ and Sr+ ion clocks, Sr lattice clock, 4 hydrogen masers
NIST Ion Clock 2025 Charged Al ion with Mg ion 5.5×10−19
NIST-F1 Cs fountain 3.1×10−16
NIST-F2 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-F2 Cs fountain 4.7×10−16
Optical clock 2012 Ca ion
Caesium Beam Atomic Clock Cs
9 Agilent 5071A caesium clocks Cs 5×10−13
KRISS-1 Cs 1×10−14
Caesium atomic clocks Cs
Five caesium clocks, one passive hydrogen maser, two active hydrogen masers Cs, H
DOST-PAGASA Juan Time
Caesium clocks, Hydrogen Maser Cs
SOC: Space Optical Clock breadboard (Sr lattice clock) Sr lattice
Deep Space Atomic Clock 2019-2021 Hg ion
Caesium atomic clocks Cs

References

  1. 1 2 3 4 "Seit wann läuft die erste Atomuhr in der PTB?". Themenrundgänge / Fragen zur Zeit. Physikalisch-Technische Bundesanstalt. Archived from the original on 2012-11-27. Retrieved 2013-02-04.
  2. ↑ Palmer, Jason. "UK's atomic clock 'is world's most accurate'". BBC. Retrieved 2013-03-02.
  3. ↑ "Research - Time and Frequency". Retrieved 2015-06-12.
  4. ↑ "NIST Ion Clock Sets New Record for Most Accurate Clock in the World". NIST. July 14, 2025. Retrieved on December 19, 2025.
  5. ↑ "A Brief History of Atomic Clocks at NIST". The National Institute of Standards and Technology (NIST). Retrieved 2013-02-04.
  6. 1 2 Newman, Michael E. (1999-12-29). "NIST-F1 Cesium Fountain Clock". NIST News. The National Institute of Standards and Technology (NIST). Retrieved 2013-02-04.
  7. ↑ "NIST Launches a New U.S. Time Standard: NIST-F2 Atomic Clock". The National Institute of Standards and Technology (NIST). Retrieved 2016-02-09.
  8. ↑ "U.S. Naval Observatory Alternate Master Clock". U.S. Navy. Archived from the original on November 26, 1996. Retrieved 2013-02-09.
  9. ↑ "Larimer County station helps set clocks". Fort Collins Coloradoan. Gannett Company. July 24, 2015. Retrieved August 27, 2018.
  10. ↑ "Mission of Japan Standard Time Group - Generation of Japan Standard Time (JST)". National Institute of Information and Communications Technology. Retrieved 2013-03-05.
  11. ↑ Motal, Julius (2011-08-30). "Japanese atomic clock is accurate to a 100 quadrillionth of a second". Geek.com. Ziff Davis, Inc. Archived from the original on 2012-06-14. Retrieved 2013-03-02.
  12. ↑ "Quantum Metrology Laboratory". RIKEN Advanced Science Institute. Archived from the original on 2013-03-03. Retrieved 2013-03-05.
  13. ↑ Takamizawa, A.; Yanagimachi, S.; Shirakawa, Y.; Watabe, K.; Hagimoto, K.; Ikegami, T., "Cesium Atomic Fountain Clocks at NMIJ" (PDF), Precise Time and Time Interval Systems and Applications Meeting, pp. 321–328, archived from the original (PDF) on 2011-04-28
  14. ↑ Wang, Yuanyuan (2012-07-12). "China unveils first optical clock". English News. Xinhuanet. Archived from the original on 2012-07-15. Retrieved 2013-02-04.
  15. ↑ "Caesium Beam Atomic Clock". The Government of the Hong Kong Special Administrative Region. Retrieved 2013-02-14.
  16. ↑ "History of Hong Kong Time Service". The Government of the Hong Kong Special Administrative Region. Retrieved 2013-02-11.
  17. ↑ "Contact us". The Government of the Hong Kong Special Administrative Region. Retrieved 2013-02-11.
  18. ↑ "Clocks and Time scales". National Time and Frequency Standard Laboratory. Retrieved 2013-02-14.
  19. ↑ "Current activities of the National Standard Time and Frequency Laboratory of the Telecommunication Laboratories" (PDF). Archived from the original (PDF) on 2013-02-17. Retrieved 2013-02-14.
  20. ↑ "Development of Korea's First Primary Frequency Standard, 'KRISS-1'" (PDF). KRISS. Archived from the original (PDF) on 2020-09-30. 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.