Comparison of the Programmable Quantum Current Generator and an Ultrastable Low-Noise Current Amplifier

The 2019 revision of the International System of Units motivated different practical realizations of the ampere according to the corresponding Mise en pratique. Independently, the national metrology institutes of France and of Germany realized the unit ampere by using Ohm's law and practical realizations of volt and ohm by means of Josephson or quantum Hall effects, respectively. In this work, we present the results of the first direct comparison of both setups with the focus on currents at the level of 50 μA and 50 nA. The relative deviations are (4±3)×10
^-7
and (14±6.5)×10
^-7
respectively.