Fig. 1. Coherent dynamics of topological defects.

(A) A spin chain is initialized in a configuration with a topological defect under the ferromagnetic Ising interaction (represented by black arrows in the upper panel). A kink appears in the middle of two ferromagnetic phases with opposite spin orientations and can propagate to the left or the right under a weak transverse field. Consequently, the spin chain evolves into a nonlocal superposition state, where the kink is simultaneously located at different positions, separated by L sites. (B) The dynamics can be understood using a quasiparticle picture. The Ising interaction acts as a potential (purple curve) that confines the kink (blue balls), while the weak transverse field acts as kinetic energy, driving the kink to neighboring sites. As the system evolves into a superposed kink state shown in the lower panel, the wave packets of the two components interfere and create fringes (blue curve), analogous to the double-slit experiment.