Within the scope of a technology transfer programme, PTB has developed a new AC quantum voltmeter in order to establish quantum-based AC voltage standards for calibrations in industry. A prototype has now been successfully tested for AC voltage at frequencies of up to 4 kHz.
Within the scope of a technology transfer project involving PTB and two partners from industry, which was supported by the Federal Ministry of Economics and Technology, a Josephson measuring system for DC and AC voltages – an AC quantum voltmeter – has been developed for use in industrial calibration laboratories. With this new system, the considerable advantages of electrical standards based on quantum effects will also become available to industrial laboratories: very low measurement uncertainties are possible without tedious re-calibrations, which have thus become more economical
The system is based on Josephson arrays, which are manufactured at PTB, and is designed for peak voltages of up to ± 10 V and frequencies of up to 10 kHz. With a prototype, AC voltages from 10 Hz to 4 kHz have already been measured at PTB, whereby uncertainties of a few μV/V within a measuring time of one minute were attained. This makes the new AC quantum voltmeter appr ox ima t e l y 20 times more accurate than conventional calibrators and 60 times faster than the measurement procedures with thermal converters used to date.
In addition, the AC quantum voltmeter can also calibrate commercial DC voltage standards (DC references and DC voltmeters) and, thus, also covers the range of commercially available DC quantum voltmeters. During a direct 10 V comparison between a DC quantum voltmeter and the new AC prototype, no significant deviation was observed within a measuring time of 15 minutes within the uncertainty limit of 0.1 nV/V.
The new AC quantum voltmeter is now being optimized by means of on-site tests at the partner's (esz AG) accredited laboratory. With this valuable end-user input, it will be developed to become a fully automated, user-friendly measuring system. The main objective is to reach a relative uncertainty of 2.5 μV/V at 1 kHz. The system will be developed in a modular approach which will allow a future extension of the system to a universal ”quantum calibrator“ for voltage, resistance and current standards. Supracon AG (instrument manufacturer), the other project partner, will be in charge of the subsequent marketing.
Ralf Behr
Department 2.6 Electrical Quantum Metrology
Phone: +49 (0)531 592-2630
ralf.behr(at)ptb.de
J. Lee, R. Behr, L. Palafox, A. Katkov, M. Schubert, M. Starkloff , A.C. Böck: An AC Quantum Voltmeter based on a 10-V programmable Josephson Array. Eingereicht bei Metrologia (2013)