Josephson junction dynamics in the presence of microresistors and an AC drive

The motion of fluxons in a long Josephson junction with point-like inhomogeneities (microresistors) and a dissipative loss is studied in a semi-analytical and fully numerical manner. It is found that the dynamic behaviour of fluxons is markedly changed by the combined effect of microresistors and an AC drive, i.e. the AC drive allows, via the microresistors, the fluxons to overcome a dissipative resistance and to move forward linearly. A physical interpretation of the significant novel phenomenon is given. First, the microresistors generate a new type of inherent localized structure, the so-called impurity mode. Then, the impurity modes are excited and amplified by the AC drive. Finally, the fluxon gains, through the strong fluxon-impurity mode (microresistor) interactions, kinetic energy to overcome the attractive potentials of the microresistors and the dissipative resistance, and it escapes from the microresistors eventually.