Quantum Systems

We investigated the gray zone width of Josephson comparators by means of circuit simulations and experiments, looking at the dependences on different circuit parameters and topologies. Eight different comparator circuits were simulated and designed for a 1 kA cm−2 niobium device. With our sophisticated measurement set-up, the lowest reported gray zone width of 3.2 μA at 4.2 K was measurable. Moreover, the results obtained allow us to derive a set of design rules for further reduction of the gray zone width, which was the original goal of our investigations.