Comparison of Josephson array voltage standards using Zener reference standards

The Josephson array voltage standard at the Beijing Institute of Radio Metrology and Measurement (BIRMM) has been used in China to realize the volt since 1992. In order to verify the accuracy and reliability of the voltage standard at the BIRMM, a comparison of the Josephson array voltage standards at 1,018 V and 10 V between the BIRMM, the Danish Institute of Fundamental Metrology (DFM) and the National Physical Laboratory (NPL), UK, has been performed. Two Zener reference standards were used to transfer the voltage between the three laboratories. The results show a difference of less than 2x10(-8).