The concept of a programmable Josephson voltage standard was first proposed in 1997. Since then a significant amount of research and development work has been devoted to the fabrication of the programmable Josephson junction array and its deployment in a voltage standard system. This paper reports the recent development of a 10 V programmable Josephson voltage standard (PJVS) system at the National Institute of Standards and Technology (NIST) and its voltage metrology applications. The superior stability of the voltage step of the new 10 V PJVS enables it to perform the same tasks as the conventional Josephson voltage standard that uses hysteretic voltage steps and to improve the efficiency and effectiveness of a JVS direct comparison. For the first time, a comparison between a conventional JVS and the NIST 10 V PJVS was performed in order to verify the NIST 10 V PJVS performance. The mean difference between the two systems at 10 V was found to be 0.49 nV with a combined standard uncertainty of 1.32 nV or a relative standard uncertainty of 1.32 parts in 10^10. Automatic comparisons between the 10 V PJVS and a 2.5 V PJVS at 1.018 V was performed to monitor the long term accuracy and stability of the 10 V PJVS and to support the electronic kilogram experiment. By matching the voltages of the two PJVS during a comparison, the Type B uncertainty can be minimized to a negligible level. The difference between the two PJVS at 1.018 V was found to be 0.38 nV with a standard uncertainty of 0.67 nV or a relative standard uncertainty of 6.7 parts in 10^10. Issues encountered during the PJVS comparison and potential 10 V PJVS applications are also discussed.
Pub Type: Journals
voltage comparison, Josephson voltage standard, programmable Josephson voltage standard, uncertainty