The ampere, a fundamental unit of electrical current, is set to undergo a major overhaul in 2018 as part of the International System of Units (SI) redefinition. Currently defined by a hypothetical scenario involving parallel conductors, the ampere will be redefined based on the elementary electrical charge (e), a fundamental constant of nature.
NIST scientists are developing a quantum-based measurement system using single-electron transport (SET) pumping to realize the new ampere standard. This nanoscale technique involves counting individual electrons moving through a microscopic quantum dot structure. While conventional SET devices can count electrons with high precision, they produce very low currents. NIST researchers are working on scaling up the current to practical levels by using all-silicon components and running multiple pumps in parallel.
The new ampere standard will be part of a broader effort to provide quantum-based measurement standards for all SI base units, known as “NIST-on-a-Chip.” It will also enable testing of Ohm’s Law in an all-quantum mechanical environment, providing a new way to validate the fundamental relationship between voltage, current, and resistance.
Source: https://www.nist.gov/news-events/news/2016/08/counting-down-new-ampere
Keywords: Single-electron transport , Quantum electrical standards , Elementary electrical charge , Metrology
