Circularly symmetric soliton states and excitations in an annular Josephson junction

The authors discuss the circularly symmetric soliton states and the I-V characteristics of an annular Josephson junction with a large width by direct numerical simulation. By assuming a soliton or multiple-soliton solution initially, they find that there exist a stable single-soliton (one-soliton) state, two-soliton state and three-soliton state in their system in the absence of an external applied field. The corresponding zero-field steps are obtained. A state that traps initially more than four solitons in the system turns out to be unstable. There exists a transition between the multiple-soliton states which suggests some physical points for the application of an annular junction. A suggestion of soliton excitation in a physical experiment is also discussed.