Automation of direct josephson voltage standard comparison and an application

A direct Comparison between two Josephson Voltage Standard (JVS) systems has been used in the Bureau International des Poids et Mesures (BIPM) key comparisons or regional supplementary comparisons to verify the performance of a JVS with an uncertainty of few parts in 10
¹⁰
. Most direct JVS comparisons were manually operated. Hardware and protocol for an automatic direct JVS comparison have been developed to improve the efficiency while retaining the same level of uncertainty attained from a manual comparison. The automatic JVS direct comparison greatly improves the efficiency of data acquisition. A case study examining the offset related to digital voltmeter (DVM) polarity in an automatic direct JVS comparison is presented.