Kink excitations and fluxon oscillators in coupled long Josephson junctions

The properties of a system of N=3 maximally coupled Josephson junctions for which symmetry is broken by having the physical parameters of one junction (the shunt junction) different from those of the other two are examined. It is found that the family of integer fluxon excitations of the symmetric case becomes distorted in a way that is best described in terms of two independent fractional fluxon subkinks theta and psi . The subkinks retain some of the qualities of quarks in that they may not be liberated from the integer-valued fluxons in which they reside, but may be created and destroyed in subkink-antisubkink pairs and exchanged in collisions. The authors have investigated forming resonant fluxon oscillators in shunt coupled Josephson-junction (JJ) systems using both bound K-K ( theta - theta ) pairs of fluxons accelerated by parallel forcing currents and bound K-K pairs ( psi - psi ) of fluxons accelerated by series forcing currents. These systems are able to accommodate larger pair breaking forces induced by forcing currents than those of similar coupled JJ systems where the pairs are bound only by mutual inductance coupling.<>