Synchronous switching of a large number of Josephson junctions

A single Josephson tunnel junction rapidly switches from zero voltage to the gas voltage of a few millivolts when the current bias exceeds the critical current. This paper describes a circuit which allows at least 400 junctions connected in series to be synchronously switched. Instead of a few millivolts for a single junction, an array of 400 junctions switches directly to one volt. The junctions, integrated into a stripline circuit similar to that described for series array voltage standards, are commonly biased by a dc current source. When the dc bias is increased the junction with the smallest critical current first switches to the normal state. This causes a pulse to propagate along normal state. The maximum number of junctions to be switched is proportional to the average critical current of the circuit. The switching time is mainly determined by the signal speed of the pulse in the stripline