Von Klitzing Constant Research Articles

The Quantum Hall Effect and Resistance Standards

Following the discovery of the quantum Hall effect in 1980 metrologists were eager to develop the effect as a resistance standard in a similar manner to the development, a decade earlier, of the Josephson effects in superconductors as a voltage standard. This article reviews the progress made by many national laboratories to assess and compare the quality and limitations of semiconductor devices, mainly silicon MOSFETs and GaAs/AlGaAs heterostructures, as quantized Hall resistance standards with values RH (i) = RK/i = h/ie2, where RK = 25812,807 Ω is the von Klitzing constant and i is an integer. Potentiometric and cryogenic current comparator bridge techniques for the measurement of RK in terms of conventional resistance standards with 1 σ relative accuracies better than 1 part in 108 are compared, and determinations of RK in ohms with accuracies as high as 2,4 parts in 108 using calculable capacitors are described. The comparison of direct determinations of RK with alternative derivations of h/e2 leading to the CCE recommendations and subsequent international adoption, from 1 January 1990, of the value 25812,807 ± 0,005 Ω for RK are also described.

The possible role of the fundamental constants in replacing the kilogram

Summary form only given. The author discusses the possibility of certain fundamental physical constants replacing the current unit of mass in the International System of Units. These constants include the Rydberg, fine-structure, Josephson, and von Klitzing constants, the atomic mass of the proton, and the proton-electron mass ratio. >

How accurate are the Josephson and quantum Hall effects and QED?

The accuracy of the theory of the Josephson effect and of the quantum Hall effect is assessed by testing quantitatively the exactness of the theoretically predicted relations K J =2 e/ h and R K = h/ e 2, where K J and R K are the phenomenological Josephson and von Klitzing constants, respectively. By assuming the relations are exact, quantum electrodynamics (QED) is tested by comparing QED-dependent and independent values of the fine-structure constant.

Changes in the values of the UK national reference standards of EMF and resistance

The reasons for the changes in the values of the UK national reference standards of EMF and resistance are discussed. The agreed values for the Josephson constant and the von Klitzing constant are given, together with a brief discussion of the evidence upon which these values are based.