Stable ground states for Δϕ=π in double Josephson junction superconducting loops

Abstract

We examine the origin of Josephson junctions with phase difference π through the dynamics of coupled Josephson junctions. We show that in a superconducting loop with an asymmetrical double junction, ground states with Δϕ=π can naturally occur. We show further that the ground state of the coupled system can possess energy minima that are deeper at nπ for n odd than n even depending upon the ratio of the critical currents in the two junctions and the McCumber parameter of the individual junctions.