Quantum Calibration System for Digital Voltmeters at Voltages from 10 nV to 1 kV

We have developed a programmable Josephson voltage standard that can generate voltages up to 20 V with a resolution of 10 nV. The standard has two superconductor-normal metal-superconductor junction arrays connected in series and driven by two radio frequency oscillators. The standard has been integrated into a digital voltmeter calibration system for voltages from 10 nV up to 1000 V. The expanded uncertainty (
k
= 2) of the system is approximately 10 nV for voltages up to 20 V and 0.9 μV/V in the voltage range from 20 to 1000 V.