Trapping of Several Solitons in Annular Josephson Junctions

We have observed for the first time a chain of sine-Gordon solitons (flux quanta) trapped in an annular Josephson junction. The low-temperature electron microscopy technique has been used in order to trap in a controlled way one by one up to several solitons in the junction. We attribute the deviations of the soliton chain velocity from the single-soliton velocity with the effects of the interaction between solitons and their bunching at high velocity.