The quantum Hall effect as an electrical resistance standard

Abstract

The quantum Hall effect (QHE) provides an invariant reference for resistance linked to natural constants. It is used worldwide to maintain and compare the unit of resistance. The reproducibility reached today is almost two orders of magnitude better than the uncertainty of the determination of the ohm in the International System of Units. This article is a summary of a recently published review article which focuses mainly on the aspects of the QHE relevant for its metrological application.

TRIMET : fermeture du triangle métrologique quantique à un niveau d'incertitude relative de 10–6

“…Concernant l'EHQ, les tests d'universalité effectués démontrent l'indépendance du produit R H (i) · i sur un nombre important de dispositifs avec des incertitudes de l'ordre de quelques 10 −10 [19][20][21]. Une nouvelle gé-nération de tests est réalisée au LNE grâce à la mise au point d'un pont de Wheatstone « quantique » capable d'atteindre des incertitudes inférieures à 10 −10 .…”

Quantum Hall Effect: Discovery and Application

“…The simplified picture of edge currents (skipping orbits) for the impressed current is incorrect (44), but fortunately, high-precision measurements of the quantized Hall resistance demonstrate that the current distribution is unimportant and that the same value is observed for different devices and materials with an incredibly small uncertainty of less than 1 part in 10 10 (45,46,47). This universality led to a worldwide agreed value for the conventional von Klitzing constant R K−90 ≡ 25812.807 in 1990.…”

A Conversation withProf. Dr. Klaus von Klitzing:Discoverer of the Quantum Hall Effect

“…It's still a very active field because you have many, many phenomena related to it. [2][3][4] The theory was already developed at the time I discovered it. Many Japanese scientists had developed the theory, 5 but nobody saw that you could measure resistance directly by macroscopic voltage and macroscopic currents because theoreticians always used combinations of constants as proportional constants.…”

“…And there is some idea to replace them by a fundamental constant. 2 We have this already with the velocity of light: the length of the meter is defined by the velocity of light. And there's some idea to fix Planck's constant as the elementary charge, Boltzmann constant as base units because they should be constant.…”