A differential programmable josephson voltage standard for low-measurement

An intrinsically accurate automated system for low-voltage measurements has been developed at NIM based on a differential programmable Josephson voltage standard. At 1 microvolt level, the typical difference between the mean value of 250 measurement points and the nominal value is 0.17 nV with the standard deviation of 1.4 nV. The experiments for uncertainty estimate have been carried out, which demonstrate the system offers a satisfactory reliability and stability. For fine-increment programmable Josephson voltage, a few expected applications are proposed.