Operating Characteristics of Josephson Four-Junction Logic (4JL) Gate

A Josephson logic gate which consists of a closed loop with four Josephson junctions (4JL gate) and its operating characteristics are described. Devices have been fabricated using Pb-alloy technology with a minimum line-width of 5 µm. Gate operations with a current gain of 2 have been performed under complete input/output current isolation. A logic delay of 20 ps per gate has been measured in a chain of ten OR-gates for a fan-out of 1 with an average power dissipation of 3.7 µW.