Abstract
The results of direct comparisons between a 1-V NbN-based programmable superconductor–normal metal–superconductor (SNS) Josephson array and a conventional superconductor–insulator–superconductor (SIS) Josephson array showed an agreement with deviations of less than 0.4 nV at voltages between 0.1 and 1 V. Null detector fluctuations caused by external noises and environmental variations that couple to the measurement system limit the measurement accuracy.