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Improved resolution of switching current measurement

We have developed a method to rapidly measure the switching current of a Josephson tunnel junction with low critical current. Measuring at low critical current presents a problem for fast measurement because the rise time of the voltage at the top of the cryostat is ultimately set by the time needed to charge the lead capacitance with a very small current. Cold amplifiers mounted close to the junction can be used to reduce the input capacitance, but this technique presents other problems and is not simple to implement.

Reported by

Royal Institute of Technology
Albanova, Roslagstullsbacken 21
SE-106 91 Stockholm