Quantum Electrical Standards
Published Online: 15 MAR 2011
Copyright © 2003 by Wiley-VCH Verlag GmbH & Co. KGaA. All rights reserved.
Encyclopedia of Applied Physics
How to Cite
Piquemal, F. 2011. Quantum Electrical Standards. Encyclopedia of Applied Physics. 267–314.
- Published Online: 15 MAR 2011
Electrical metrology entered a quantum era on 1 January 1990, the date on which the Comité International des Poids et Mesures (CIPM) recommended that the quantum Hall effect (QHE) and the Josephson effect (JE) be taken as the primary standards of resistance and voltage, respectively. These phenomena link these electrical quantities directly to the Planck constant h and the elementary charge e, through the von Klitzing constant RK and the Josephson constant KJ, which are presumably equal to h/e2 and 2e/h, respectively. They insure for the corresponding units, the ohm and the volt, a high level of reproducibility and a unique representation all over the world. Moreover, with the development of electromechanical systems such as a calculable capacitor or a watt balance, the use of these quantum standards allows the determination of the key constants of the quantum mechanics, such as the fine structure constant α = μ0c/(2h/e2) and the Planck constant. Similarly, the Coulomb blockade of single-electron tunneling could be a basis for a quantum current standard whose amplitude is equal to the product of the elementary charge and a frequency. It provides the third leg of the quantum metrological triangle and makes a direct determination of the elementary charge possible. This chapter gives an overview of the quantum Hall resistance standards and the Josephson voltage standards and the prospect of new quantum standards based on the Coulomb blockade. The experiments aimed at determining the involved fundamental constants and at checking their consistency in terms of the Planck constant and the elementary charge are described and discussed.
- quantum Hall effect;
- Josephson effect;
- Coulomb blockade;
- single-electron tunneling;
- two-dimensional electron gas;
- electrical standards;
- quantum metrological triangle and fundamental constant