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In the present International System of Units (SI), the Josephson effect and quantum Hall effect have been utilized for voltage and resistance primary standards, and the electrical current standard has been derived from a combination of the two quantum standards. In 2018, it is planned that the SI will be revised based on the latest measurements results of the Planck constant, elementary charge, Avogadro constant, and Boltzmann constant. The adoption of the ‘Revised SI’ means we shall finally terminate the traceability of the kilogram tied to an artifact (the international prototype of the kilogram) and start a new traceability of the kilogram to the Planck constant h. In electricity and magnetism metrology, and related precision measurements, the traceability presently based on the ‘conventional values’ of the Josephson constant and the von Klitzing constant is going to be switched to the revised traceability based on the Planck constant and elementary charge. In this article, the foundation of the quantum electrical measurements and how the Revised SI, which is based purely on fundamental physical constants and quantum effects, will bring us a long-term benefit with negligible impact to industry are detailed. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

The National Metrology Institute of Japan (NMIJ) has developed a new national standard of capacitance (capacitance standard) and also established its traceability system. Calibration and measurement capabilities (CMCs) of the new capacitance standard were validated in the international comparison with foreign National Metrology Institutes (NMIs). However, it is not easy to frequently carry out such international comparison which requires close coordination among the participating NMIs. In order to maintain high reliability of the capacitance standard, therefore, it is important to verify its CMCs during the period when the comparisons are not carried out. To verify the CMCs, NMIJ has been performing long-term monitoring of standard capacitors and of capacitance differences among a number of standard capacitors. In this paper, we will report the details of the long-term monitoring of the standard capacitor, the long-term monitoring results of capacitance differences, and verification of CMCs based on the analysis of these results. Validation of the CMCs based on results of monitoring conducted after the massive earthquake on March 11, 2011 is also described as specific case. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

All the contact pads of a quantized Hall resistance (QHR) device should have a low contact resistance (∼1 Ω) for the application of DC resistance standard devices at cryogenic temperatures. Corrosion of a GaAs/AlGaAs substrate occurs along the edge of the photoresist before the deposition of Ni/AuGe, and we assume that this corrosion degrades the contact resistance. A SiO2 protective layer is effective in preventing the corrosion of and protecting the surface of GaAs/AlGaAs substrate. With the use of this SiO2 protective layer, the yield ratio of the contact resistance to the twodimensional electron gas (2DEG) layer at low temperature (∼0.5 K) and high magnetic field (∼9 T) improves to nearly 100%. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)