Review of quantum electrical standards and benefits and effects of the implementation of the ‘revised SI’

Abstract

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.