Noise margins for Josephson logic and memory devices

Noise which can produce erroneous transitions in Josephson logic devices can be treated in terms of the familiar model for thermal activation of a particle over a potential barrier. Noise curves are calculated which represent the effective threshold curves for a given transition rate; this approach can be applied to the mode-to-mode (superconducting) transitions as well as to the mode-to-voltage state switching. The analysis will be illustrated with the example of a three-junction current injection device. The practical consequences for design of Josephson logic circuits will be indicated.