The ampere enters the quantum era: A worldwide breakthrough in the field of metrology

A team of LNE researchers has produced a quantum electrical current standard that, in addition to being both universal and practical, is capable for the first time of generating currents whose intensities within the microampere-to-milliampere range are correlated with the elementary charge, offering a relative uncertainty of ten parts per billion (i.e. 10^–8).

The International System of Units (SI), which has been built on the seven basic units (i.e. kilogram, ampere, meter, Kelvin, second, mole and candela), should be undergoing a major evolution in 2018: during the General Conference on Weights and Measures to be held in Paris, scientists intend to modernize this SI System through association with the field of modern physics. Some units need to be redefined no longer on the basis of material artifacts but instead derived from fundamental constants found in physics (the elementary charge for the ampere, Planck's constant for the kilogram, etc.), as well as through reliance on quantum physics. The aim herein is to reduce measurement uncertainty, yet the actual standards to fulfill these definitions still need to be developed.

Such is now the case for the ampere thanks to LNE's exploit.

This breakthrough, with worldwide implications, was conducted within LNE's Quantum Electrical Metrology Division by the team under the supervision of Jérémy Brun-Picard, Sophie Djordjevic, Dominique Leprat, Félicien Schopfer and Wilfrid Poirier. They collectively built a quantum electrical current standard that is both universal and practical.

Explore their work and results published in the scientific review entitled American Physical Society (APS), Physical Review X (PRX): J. Brun-Picard, S. Djordjevic, D. Leprat, F. Schopfer and W. Poirier, "Practical Quantum Realization of the Ampere from the Elementary Charge", Phys. Rev. X, 6, 041051 (2016).