A Two-Way Josephson Voltage Standard Comparison Between NIST and NRC

A two-way Josephson voltage standard (JVS) direct comparison between the National Institute of Standards and Technology (NIST) and the National Research Council (NRC) has been conducted. The process consists of two comparisons: first, using the NRC JVS with the NRC's measuring system (hardware and software) to measure the 10 V provided by the NIST JVS and then using the NIST JVS measuring system to measure the 10 V provided by the NRC JVS. The results of the two comparisons are in agreement to within 0.7 nV, and their mean indicates that the difference between the two JVSs at 10 V is -0.28 nV, with a pooled combined uncertainty of 2.07 nV (k = 2) or a relative uncertainty of 2.1 parts in 10¹⁰.

I. Introduction

The bureau International des Poids et Mesures (BIPM) has been providing the National Metrology Institutes (NMIs) with Josephson voltage standard (JVS) direct comparisons that are within the scope of BIPM Key Comparison EM.BIPM-K10.b at 10 V [1]. Most of these comparisons have been performed under the BIPM protocol Option B, where BIPM provides a stable voltage at 10 V, and the NMI's JVS takes measurements against the BIPM JVS voltage [2]. A more complete direct Josephson comparison would include two sets of measurements, with each JVS system taking a set of measurements.