The Josephson effect has revolutionized voltage metrology [1-5] and, together with the quantum Hall effect for resistance and atomic clocks for time and frequency, has enabled measurement standards based on quantum effects. Quantum standards produce intrinsically accurate values that enable repeatable precision measurements in any laboratory using comparable devices, systems and measurement techniques. Quantum standards are inherently different from non- quantum, artifact standards, whose values depend on environmental conditions. The success of quantum standards has lead the international community to redefine the international system of units and how measurement uncertainty is assigned via fundamental constants. [6-8] In this chapter, I will discuss the features and characteristics of dc and ac quantum voltage standards, the state-of-the-art technology of devices, circuits and instrumentation for voltage standard systems, and how they are presently applied to voltage and temperature metrology. Throughout, I will indicate how appropriate measurement techniques are required to minimize the systematic errors and realize measurements that approach quantum-accuracy.
Fundamentals and Frontiers of the Josephson Effect
Springer Series in Materials Science, New York, NY