Optimization of high-T/sub c/ Josephson fluxon-antifluxon transistors based on numerical simulation

A Josephson fluxon-antifluxon transistor (JFAT) can be constructed utilizing high-T/sub c/ bicrystal or SNS long junctions with a control line on top of the junction, This device can be modeled numerically by solving the perturbed sine-Gordon equation. A JFAT has a higher current gain and a faster transient response compared to a conventional Josephson flux-flow transistor which has a U-shaped control line on top of the long junction. Dependences of the control characteristics on the width and the location of the control line, as well as on the junction length are calculated. The influence of a superconducting ground plane on device characteristics are also discussed. These results are important to the design of high-T/sub c/ digital circuits based on JFATs.