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Flexible Josephson metrology system

Quantum-based generation and measurement of voltage signals

PTBnews 3.2023
Especially interesting for

Calibration laboratories

Metrology institutes

Quantum electrical metrology

Working within an industrial cooperation project, PTB has developed a novel metrology system for the quantum-based generation and measurement of voltage signals. The system is based on a pulse-driven Josephson standard, the Josephson arbitrary waveform synthesizer (JAWS), and has been designed for deployment in a wide variety of applications. This system can be used not only as a quantum-based voltage generator, but also as an ultra-accurate instrument for measuring DC voltages and AC voltage signals. A prototype has been successfully tested at PTB for signal frequencies up to 100 kHz.

Prototype of the new JAWS metrology system

Josephson voltage standards based on JAWS allow electric voltages with arbitrary and spectrally pure waveforms to be generated with “quantum accuracy”. This explains their use in a large number of metrological applications. Metrology institutes such as PTB are already successfully using JAWS in a wide frequency range from a few Hz up to 1 MHz, for example as a reference for AC voltages, for setting up novel user-friendly impedance bridges, and for calibrating noise amplifiers for the “electronic kelvin”.

Within the scope of a technology transfer project funded by the German Federal Ministry for Economic Affairs and Climate Action (BMWK) as part of the TransMeT funding program, PTB is developing – in cooperation with two industrial partners – a novel product based on JAWS: The JAWS Source Measurement Unit (JAWS-SMU) can not only generate voltages with quantum accuracy (Source mode), but can also be used in Measurement mode as an ultra-accurate measuring instrument for DC and AC voltages (waveforms). In Source mode, measuring instruments can be directly calibrated by applying a well-defined voltage with accuracies in the nV/V range. For example, the linearity behavior of voltmeters for DC voltages between 1 nV and 100 mV was measured, and the properties of analogue-to-digital converters were characterized by means of sine waves up to 100 kHz. As the system is also capable of generating signals with an accurately defined phase, it can also be used for the calibration of phase standards. In Measurement mode, the voltage signal of a source is compensated by means of JAWS, and the small residual voltage is measured by a null detector. With the quantum standard as reference, relative measurement uncertainties in the range of 10 nV/V can be achieved within minutes.

As their practical advantages over conventional systems make quantum electrical standards interesting for industrial applications as well (in calibration laboratories, for example), the JAWS-SMU has also been designed for reliable operation in “harsh” environments. A prototype has already been used at PTB to demonstrate precision measurements with effective output voltages up to 100 mV. Within the scope of on-site tests at the project partner’s (esz AG) accredited calibration laboratory, the next step will consist in optimizing the prototype for practical use. It will then be developed into a completely automated, user-friendly product. Supracon AG (instrument manufacturer and project partner) will be in charge of the subsequent commercialization. Long-term planning includes an increase of the output amplitudes to 1 V.


Ralf Behr
Department 2.6
Quantum Electrical Metrology
Phone: +49 531 592-2630
Opens local program for sending emailralf.behr(at)ptb.de

Scientific publication

J. Herick, R. Behr, O. Kieler, L. Palafox: Development of JAWS-SMU. Conference on Precision Electromagnetic