A superconducting galvanometer employing Josephson tunnelling

Abstract The phenomenon of Josephson tunnelling has been applied to the detection of low voltages at liquid helium temperatures. A new technique for the manufacture of specimens displaying double-junction characteristics has been developed and a theory for their behaviour suggested. The junctions have been used in a practical voltmeter to achieve a sensitivity of 10−14 v with a time-constant of 1 sec; the sensitivity may be extended indefinitely for a proportionate increase in the time-constant.