Breathers in a single plaquette of Josephson junctions: existence, stability and resonances

We present a theoretical study of inhomogeneous dynamic (resistive) states in a single plaquette consisting of three Josephson junctions. These breath er states are found to exist in a large range of control parameters (d.c. b ias gamma, anisotropy eta and self-inductance beta (L)). We perform an anal ytical analysis of these states, and their stability and resonance behaviou r. Numerical calculations confirm our results and show that instabilities a rise due to resonant interactions between the breather and electromagnetic oscillations (EOs) mediated by the breather state. These instabilities mani fest themselves by various nonlinearities, resonant steps and voltage jumps in the current-voltage characteristics. (C) 2001 Elsevier Science B.V. All rights reserved.