Electrical Quantum Metrology Standard for the Synthesis of Ac Voltages

A prototype Josephson quantum standard for synthesizing sine waves characterised by low-level harmonics and high accuracy was developed, opening up new possibilities for metrological support in the area of ac voltage. The standard includes a cryogenic probe with Josephson chips, a delta-sigma modulator, a pulse pattern generator, a compensation circuit, a spectrum analyzer, a video control unit, as well as special software. A capability of sine wave synthesis with an output voltage up to 130 mV RMS over a wide frequency range from 1 kHz to 100 kHz is demonstrated. Higher harmonics are suppressed below the noise floor up to 100 dBc.