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Comparison of NIM and BIRMM programmable Josephson voltage standards
Abstract
A comparison between the National Institute of Metrology (NIM) and the Beijing Institute of Radio Metrology and Measurement (BIRMM) Programmable Josephson Voltage Standards (PJVS) at 1 V level was carried out at Changping campus of NIM from November 16 to November 17, 2009. The measured difference voltage between the two PJVS is 2×10-10 in direct comparison and 4×10-9 in indirect comparison. The results of this comparison have demonstrated excellent agreement between the NIM and the BIRMM PJVSs.
... However because of the stair-case waveform, it is not really an AC comparison but a DC comparison although the systems are compared very quickly. Thus only direct DC comparison of two PJVS was carried out till today ( [2], [3]). ...
This document presents some considerations on the future inter-comparison of AC Programmable Josephson Voltage Standards (ACJVS) between two National Metrology Institutes. Namely Türkiye Bilimsel ve Teknolojik Araştirma Kurumu (TUBITAK) and Czech Metrology Institute (CMI) are considered as candidates.
A new programmable Josephson voltage standard (PJVS) at 1 V level was developed at National Institute of Metrology (NIM), China. This system is able to generate dc voltage and stepwise-approximated ac voltage at frequencies up to 1 kHz. The relative uncertainty of Zener voltage reference calibration at the level of 1.018 V is better than 3×10 −9 . The uncertainty of synthesized ac waveform is better than 1ppm. We have carried out some applications with the synthesized ac waveform, for instance, a new approach of magnetic flux measurement was proposed by measuring the flux difference between the rectangular pulses synthesized by the Josephson system and the flux under test. Furthermore, a new method was developed to precisely calibrate the Fluke 5720A calibrator, which measures the difference between the fundamental rms value of ac voltage offered by the Fluke 5720A and the stepwise-approximated ac voltage generated by the Josephson system via a Lock-in Aamplifier (LIA) as a null detector.
A comparison between the National Institute of Standards and Technology (NIST) and the National Research Council (NRC) Josephson voltage standards (JVS) was carried out at the NRC from 13 August to 17 August 2007. The comparison was made at the 10 V level. It was a two-way direct JVS comparison, which means that the NIST JVS provided a voltage at 10 V and was measured against the NRC JVS with NRC's measuring system (hardware and software). The comparison was repeated by using the NIST JVS measuring system to measure a voltage at 10 V provided by the NRC JVS. The results from the two comparisons were consistent. The difference between the NIST CJVS and the NRC JVS is −0.28 nV with an expanded uncertainty (k = 2) of 2.07 nV at 10 V or 2.07 parts in 10¹⁰.
Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.
The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).
Comparisons of the 1 V Josephson array voltage standard of the Bureau International des Poids et Mesures (BIPM) were made with that of the National Institute of Metrology (NIM), Beijing, China, in November 1995. The results agree within an overall uncertainty of less than 1 nV.
A comparison of the 10 V Josephson array voltage standard of the Bureau International des Poids et Mesures (BIPM) was made with that of the National Institute of Standards and Technology (NIST), USA, in March 2009. For this exercise, three different measurement methods were carried out: the two different options of the BIPM.EM-K10.b comparison protocol as well as the measurement protocol applied by NIST. The results of both participants are in very good agreement and the overall relative standard uncertainty is 9.5 parts in 1011.
Main text.
To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.
The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).
An interlaboratory comparison of Josephson voltage standards has
been made among 16 national, industrial, and military standards
laboratories in North America and 1 in Germany. The comparison was made
at 10 V using a set of four transfer Zener reference standards. A pivot
laboratory made measurements at the beginning, end, and at 9 other times
during the comparison. The measured differences and their uncertainties
are used to establish a table of equivalence between all pairs of
participants
Steps taken during the course of developing a Josephson junction
array voltage standard to achieve a measurement uncertainty of better
than 2×10-8 are described. They consist of improving
the frequency stability of the Gunn oscillator by proper design of the
phase-locked loop, choosing a digital voltmeter (DVM) with high
resolution, low drift, and low noise emission for use as a null
detector, and designing line filters to reduce noises introduced into
the Josephson junction array
During the course of developing the Josephson junction array voltage standard at the ETL, the following precautions have been taken to improve its uncertainty; 1) New design and construction of a phase-lock circuit to obtain a stable millimeter wave frequency; 2) Optimum choice of a digital voltmeter for use as a suitable null detector; 3) Design and construction of line filters to reduce noise coming to the the Josephson junction array. These predictions are essential to a stable voltage calibration with an uncertainty of 1.3 x 10-8.