 Brian Josephson

Brian Josephson predicted that weakly coupled superconductors can carry a phase-dependent current. In the ideal Josephson effect, $I=I_c\sin \varphi$ relates the current to the condensates' phase difference, while $\dot{\varphi }=2eV/\hslash$ determines its evolution under a voltage. A constant voltage therefore gives an alternating current with frequency $2eV/h$. The relations make a macroscopic quantum phase measurable through electrical behavior and connect superconducting coherence with precision frequency and voltage experiments.^[ref]

Identity source: www.nobelprize.org/prizes/physics/1973/press-release/