This paper introduces a four-terminal-pair impedance bridge based on pulse-driven Josephson junctions arrays which is designed to link any kind of impedance to the quantized Hall resistance. The unique features of the quantized Hall resistance in a multiple series connection allows to dispense a combining network and leads to a compact and simple design of the whole setup. Moreover, the low noise of a quantized Hall resistance reduces the measurement time compared to resistance standards at room temperature which is essential for the characterization of quantum Hall devices in the AC regime. A first measurement campaign confirmed the expected low noise of 1.82  n V / H z for a link to a 10 nF capacitance standard. The repeatability of the bridge was found to be few parts in 108. Capacitance and resistance standards were measured at 1233.15 Hz against graphene based quantum Hall resistance devices.

This paper reports on the comparison of two Josephson arbitrary waveform synthesizers for frequencies up to 500 kHz. Both independent pulse-driven Josephson arrays produce a 10 mV RMS sinusoidal voltage. They are alternately connected to an analog-to-digital converter which serves as a transfer standard. The setup is capable to of synthesizing quantum-based waveforms using two different pulse-bias techniques. We use the Zero-Compensation method and a two-pole high-pass filter structure in the pulse-bias configuration of one system (the reference) to minimize the amplitude error for signal frequencies up to 500 kHz. Consequently, we are able to directly detect the high-frequency voltage errors in the other system (the device under test). The setup is used to measure differences between both systems, and the influence of parameter variation on the results with Type A uncertainties of 0.4 µV/V (k = 1) in measurement times of 60 s. We find that the dominant sources of deviations above 10 kHz can be traced to the influence of the output cabling and the pulse bias on the synthesized voltage signal. Our analysis explains the origin and the reduction of these high-frequency voltage errors.

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60 years after the discovery of the Josephson effect, electrical DC voltage calibrations are routinely performed worldwide - mostly using automated Josephson voltage standards (JVS). Nevertheless, the field of electrical quantum voltage metrology is still propagating towards AC applications. In the past 10 years the fabrication of highly integrated arrays containing more than 50 000 or even 300 000 junctions has achieved a very robust level providing highly functional devices. Such reliable Josephson arrays are the basis for many novel applications mainly focussing on precision ac measurements for signal frequencies up to 500 kHz. Two versions of quantum AC standards are being employed. Programmable Josephson voltage standards (PJVS), based on series arrays divided into subarrays, reach amplitudes up to 20 V and usually are used as quantum voltage reference in measurement systems. Pulse driven arrays reach amplitudes up to 1 V or even 4 V and are typically used as Josephson arbitrary waveform synthesizers (JAWS). This paper summarizes the principal contributions from PTB to the present state of Josephson voltage standards with particular focus on developments for precision metrological applications and our proof-of-concept demonstrations.