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Enabling ultimate metrological Quantum Hall Effect (QHE) devices

Short Name: ULQHE, Project Number: T4.J04
Since 1990the Quantum Hall Effect (QHE) has been used as the primary reference for the electrical resistance. This physical phenomenon based on quantum electronic properties of a two dimensional conductor in presence of a high magnetic field allows the generation of an electrical resistance, the Hall resistance RH.

Research experiments on the RH quantization already demonstrated that the effect is universal (so is independent of the material, its electronic properties, the geometrical shape and size of the conductor) and reproducible with relative accuracies. Exactness, reproducibility, universality, intrinsically referenced character are the qualities which ensure the QHE to be the ideal candidate for the ohm metrology. The QHE offers the possibility to link the ohm to the fundamental physical constants h and e.

This ability is very crucial for the project of redefinition of the Système International of units (SI) based on fundamental constants of physics which is presently focusing the efforts of metrologists. For instance the QHE directly contributes to make the watt balance an experiment able to link the kilogramme to the Planck constant and it is partly this effect which made this experiment the most promising route for a new definition of the mass unit.

Objective of the project was to perform new universality and quantization tests of the QHE. Another goal was the exploration of new innovative and promising materials with high potential for the QHE metrology and, for instance, to become the future improved, or even revolutionary, quantum resistance standard, like Graphene. Finally, the project aimed at contributing to the metrological characterization, investigation and validation of quantum resistance standards prototypes, the so called Quantum Hall Arrays Standards (QHARS).


Electricity and Magnetism
2008 - 2010