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Pulse-Driven Josephson Voltage Standards: Development and Metrological Applications

We use Josephson arrays that are driven by very short current pulses to generate ac voltage. These arrays are produced by Work Group 2.43 inside the clean room facility at PTB. A detailed explanation of the Josephson Arbitrary Waveform Synthesizer (JAWS) can be found here.


The experimental JAWS system is based on a pulse generator, which send ternary pulses (-1 / 0 / +1) with a pulse repetition frequency of 15 GHz to the arrays. The chips are located in liquid Helium at a Temperature of 4.2 K (about -269 °C). The JAWS allows us to create arbitrary waveforms in the time and frequency domain, which is of high interest for a wide number of applications.


In August 2014, we achieved an RMS voltage of 1 V (peak-to-peak voltage: 2.845 V), together with Work Group 2.43, by connecting eight arrays with a total of 63,000 junctions in series.

 

Schematic diagram of a 1 V JAWS system

Schematic diagram of a 1 V JAWS system. 4 Josephson-chips with 8 Josephson-arrays are connected in series, but driven in parallel by the pulse generator. A Spectrum-Analyser shows the purity of the output waveform.

 

 

Cryoprobe with screen removed and boards with Josephson chips

Lower end of the Cryoprobe with screen removed. The electrical connections and two boards with Josephson chips are clearly visible.

 

 

 

1 V JAWS system

A 1 V JAWS system and setup. The Cryoprobe is immersed in the Cryostat, control electronics including the pulse generator are to the right.

 

Publications of the working group


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