List of atomic clocks

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

Name	Operation date	Type	Accuracy	Location	Image
CS1[1]	1969	Cs	7×10−15	Physikalisch-Technische Bundesanstalt Braunschweig,  Germany
CS2[2]	1985	Cs	1.2×10−14	Physikalisch-Technische Bundesanstalt Braunschweig,  Germany
CS3	1988	Cs		Physikalisch-Technische Bundesanstalt Braunschweig,  Germany
CS4	1992-2005	Cs		Physikalisch-Technische Bundesanstalt Braunschweig,  Germany
CSF1[3]	1999	Cs fountain	4×10−16	Physikalisch-Technische Bundesanstalt Braunschweig,  Germany
CSF2[4]	2009	Cs fountain	2×10−16	Physikalisch-Technische Bundesanstalt Braunschweig,  Germany
FOCS				Federal Institute of Metrology Wabern, Switzerland
NPL-CsF2, Yb+ and Sr+ ion clocks, Sr lattice clock, 4 hydrogen masers[5][6]				National Physical Laboratory Teddington, London,  United Kingdom
NIST-F1,[7]		Cs fountain	3.1×10−16	NIST Boulder Laboratories Boulder, Colorado  United States[8]
NIST-F2[9]		Cs fountain	1.1×10−16	NIST Boulder Laboratories Boulder, Colorado  United States[10]
USNO Alternate Master Clock				Schriever Air Force Base El Paso County, Colorado  United States[11]
WWV				WWVB Larimer County, Colorado  United States[12]
Department of Defense master clock				United States Naval Observatory Washington, D.C.  United States
18 cesium atomic clocks and 4 hydrogen maser clocks		Cs, H		National Institute of Information and Communications Technology Koganei,  Japan[13]
Optical lattice clock				University of Tokyo Bunkyō, Tokyo,  Japan[14][15]
NMIJ-F1, NMIJ-F2[16]		Cs fountain	4.7×10−16	National Metrology Institute of Japan Tokyo,  Japan
Optical clock[17]	2012	Ca ion		Hubei,  China
Caesium Beam Atomic Clock[18][19]		Cs		Hong Kong Observatory Tsim Sha Tsui, Hong Kong  China[20]
9 Agilent 5071A caesium clocks[21]		Cs	5×10−13	National Standard Time and Frequency Laboratory Taoyuan,  Taiwan[22]
KRISS-1[23][24]		Cs	1×10−14	Korea Research Institute of Standards and Science Daejeon,  South Korea
Caesium atomic clocks[25]		Cs		National Metrology Centre Queenstown,  Singapore
Five caesium clocks, one passive hydrogen maser, two active hydrogen masers.[26]		Cs, H		National Physical Laboratory of India New Delhi,  India
DOST-PAGASA Juan Time[27]				Department of Science and Technology Taguig,  Philippines
Caesium clocks, Hydrogen Maser [28]		Cs		Indonesian Institute of Sciences Jakarta,  Indonesia
SOC: Space Optical Clock breadboard (Sr lattice clock)[29]		Sr lattice		European Space Agency Düsseldorf, Germany Braunschweig, Germany Birmingham, United Kingdom Paris, France Florence, Italy Turin, Italy Prague, Czech Republic
Deep Space Atomic Clock[30]	2019-2021	Hg ion		Jet Propulsion Laboratory La Cañada Flintridge, California  United States
Caesium atomic clocks[31]		Cs		Laboratorium Czasu i Częstotliwości (CBK PAN) Borówiec,  Poland