Edwin R. Williams, Richard L. Steiner, David B. Newell
Using a moving coil watt balance, electric power measured in terms of the Josephson and quantum Hall effects is compared with mechanical power measured in terms of the meter, kilogram and second, we find the Planck constant h = 6.62606891(58) x 10-34 Js. The quoted standard uncertainty ( 1 standard deviation estimate) corresponds to (8.7 x 10-8) h. Comparing this measurement places an upper limit of 2 x 10-8 / year on the drift rate of the SI unit of mass, the Kilogram.
Physical Review Letters
electron mass, fundamental constants, Josephson constants, kilogram, mass drift, Planck constant, Watt-SI
, Steiner, R.
and Newell, D.
An Accurate Measurement of Planck's Constant, Physical Review Letters
(Accessed December 10, 2023)