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Quasi-continuous voltage standard using sinusoidal and pulse-driven Josephson junction arrays



Dimitrios Georgakopoulos, Ilya Budovsky, Samuel P. Benz


Josephson voltage standards (JVSs) provide a primary realization of the volt, the unit of electromotive force. They generate direct (dc) voltages up to 10 V and show agreement better than 1 nV/V at 10 V. For JVSs based on the sinusoidal [or continuous-wave (CW)]-driven Josephson junction arrays, JJA, the voltage resolution over the whole voltage range is limited to the voltage across one Josephson junction (typically from 5 µV to 155 µV) and to achieve this resolution, depending the specific chip configuration, they may require a perfect chip (i.e. no missing Josephson junctions and all the Josephson junctions having flat zero and first quantized voltage steps). For voltages higher than the voltage across one Josephson junction, some of the existing CW driven JJAs JVSs can achieve quasi-continuous voltages by adjusting the frequency. For pulse-driven JJA based JVSs, the voltage resolution over the whole voltage range is limited by the length of the pattern of pulses required to drive the JJA, which can be of the order of several hundreds of megabits, depending on the number of junctions of the JJA, and to achieve their maximum voltage they require high performance electronics (i.e. high bandwidth, low distortion and jitter, and pulse shaping filters). We have developed a new dc voltage standard based on the combination of CW- and pulse-driven Josephson junction arrays (JJAs) that can generate quasi-continuous voltages up to the sum of the full-scale voltages of the CWCW- and pulse-driven JJAs that is robust to the imperfections of the Josephson junctions and has relaxed requirements to the RF electronics driving the JJA compared to the existing PD-JJA based JVSs. By use of the JJA chip at NMIA, we demonstrate its feasibility to generate voltages up to 1 V. The voltage uncertainty is some nanovolts and the theoretical resolution is better than 1 nV over the whole voltage range. The main requirement for the system operation is that all the Josephson junctions must have quantum locking ranges with respect to the power of the radio frequency (RF) bias and for the pulse-driven JJAs flat first quantum step. We anticipate that the new system will make possible the use of imperfect JJA-chips and allow the use of simpler RFRF driving electronics without compromising the system performance, and possibly allow the use of Josephson voltage standards in the feedback loop of control systems.
Measurement Science and Technology


Josephson arbitrary waveform synthesizer, Josephson junction, Josephson standards, programmable Josephson voltage standard, quantum electrical standards, voltage generation


Georgakopoulos, D. , Budovsky, I. and Benz, S. (2022), Quasi-continuous voltage standard using sinusoidal and pulse-driven Josephson junction arrays, Measurement Science and Technology, [online],, (Accessed June 17, 2024)


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Created November 16, 2022, Updated May 21, 2024