The AC Quantum Voltmeter Used for AC Current Calibrations

In this work we present a method to use the AC quantum voltmeter setup for the measurement of ac currents up to 1 kHz frequencies. Besides the typical dc and ac voltage calibrations of programmable Josephson voltage standard arrays the area of application is extended. A commercial Fluke 5720A calibrator was investigated as current source in the frequency range from 10 Hz to a few kilohertz and it could be shown, that its stability and accuracy is much better than specified. The measured standard deviation in our setup varies from $0.5\ \mu \mathbf{A}/\mathbf{A}$ to 5 μA/A.