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The Kibble balance and the kilogram



Stephan Schlamminger, Darine El Haddad


Dr. Bryan Kibble invented the watt balance in 1975 to improve the realization of the unit for electrical current, the ampere. With the discovery of the Quantum Hall e ect in 1980 by Dr. Klaus von Klitzing and in conjunction with the previously predicted Josephson e ect, this mechanical apparatus could be used to measure the Planck constant h. Following a proposal by Quinn, Mills, Williams, Taylor, and Mohr, the Kibble balance can be used to realize the unit of mass, the kilogram, by xing the numerical value of Planck's constant. Since 2017, the watt balance is called Kibble balance to honor the inventor, who passed in 2016. This article explains the Kibble balance, its role in the rede nition, and attempts an outlook to the future.
Comptes Rendus Physique


Kibble balance, revised SI, kilogram
Created March 25, 2019, Updated October 8, 2019