Improvements of the programmable quantum current generator for better traceability of electrical current measurements

TL;DR

This paper presents improvements to a quantum current generator that reduce noise and enhance the traceability and accuracy of electrical current measurements, enabling better calibration of ammeters and precise realization of the ampere.

Contribution

The authors improved the quantum current generator to achieve lower noise levels and validated its performance through calibration and comparison with national standards.

Findings

Noise reduction in the quantum current generator

Calibration of ammeters with lower uncertainties

Agreement of ampere realizations within 3.7 parts in 10^7

Abstract

A programmable quantum current generator based on the application of Ohm's law to quantum voltage and resistance standards has demonstrated a realization of the ampere from the elementary charge with a $10^{-8}$ relative uncertainty [J. Brun-Picard et al. PRX 6, 041051, 2016]. Here, we report on improvements of the device leading to a noise reduction of the generated quantized current. The improved quantum current generator is used to calibrate different ammeters with lower measurement uncertainties. Besides, measurements of its quantized current using a calibrated Ultrastable Low-Noise Current Amplifier (ULCA) have shown that the realizations of the ampere at PTB (Physikalisch-Technische Bundesanstalt) and LNE (Laboratoire national de m\'{e}trologie et d'essais) in the range $\pm50$ $\mu$A agreed to -3.7 parts in $10^{7}$ with a combined standard uncertainty of 3.1 parts in $10^{7}$ (coverage factor $k_\mathrm{c}=1$).