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

Abstract

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 $\mu\hbox{V/V}$ in the voltage range from 20 to 1000 V.