UNDERDAMPED LONG JOSEPHSON-JUNCTION COUPLED TO OVERDAMPED SINGLE-FLUX-QUANTUM CIRCUITS

We report a circuit that integrates an underdamped long Josephson junc tion with overdamped single-flux-quantum (SFQ) circuits. We confirm th at the resonant soliton modes in the long junction are not affected by SFQ cells coupled to the junction, and demonstrate that the radiation frequency and linewidth of the soliton resonances can be measured wit h SFQ T-flip-flops. Our experimental results also show that a 4 pi qua ntum mechanical phase leap at the end of the long junction, which is d ue to the reflection of a soliton, creates two single flux quanta prop agating in the overdamped Josephson transmission line. (C) 1997 Americ an Institute of Physics.