Accurate measurements with Josephson-based quantum voltage standards

In this article, we present a range of quantum-based measurement systems that we have developed for applications in the field of metrology. The core of these systems are Josephson arrays, which we manufacture in our clean room. Pulse-driven Josephson voltage standards are used in Josephson impedance measuring bridges. Due to their flexibility automated impedance calibrations can be performed over a wide frequency range from 50 Hz to 50 kHz in a single bridge. At 1233 Hz uncertainties of parts in 10⁹ for 1:1-capacitance ratios with 10 nF are realised – comparable to world-class IVD-based impedance bridges. Programmable Josephson voltage standards allow us to calibrate DC and AC voltages with uncertainties at the level of parts in 10¹⁰, few parts in 10⁸ (up to kHz range), and below 5 parts in 10⁶ up to 100 kHz, respectively.