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

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 [1]. 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 métrologie et d'essais) in the range ±50 µA agreed to -3.7 parts in 10 7 with a combined standard uncertainty of 3.1 parts in 10 7 (coverage factor k c = 1).