High-Precision Test of the Universality of the Josephson Voltage-Frequency Relation

Abstract
The Josephson voltage-frequency relation has been compared between two quite different (and nonideal) types of Josephson junctions—an indium microbridge and a planar normal-metal barrier junction of niobium with a copper normal region. It is found that the constant of proportionality between voltage and frequency is the same in both the junctions to at least 2 parts in 1016.