On the Use of the AC Josephson Effect to Maintain Standards of Electromotive Force

Abstract

It is shown how a particular phenomenon arising from the ac Josephson effect in superconductors can be used to provide a comparatively simple and inexpensive means for (1) checking on the constancy in time of reference standards of electromotive force, and (2) relating the reference standard of one country to that of another country, thereby contributing to a better international assignment of the volt. The results of recent high accuracy (4 ppm) measurements of the phenomenon in question and the relative ease with which the techniques used in these measurements can be extended to the 1 ppm level will be presented as evidence that these two goals can be reached in the near future.