Interaction-induced breakdown of chiral dynamics in the Su-Schrieffer-Heeger model

The effect of interparticle interactions on topological properties is difficult to experimentally probe and quantitatively characterize. For ultracold atomic systems, although topological phases and phenomena have been recently observed in various settings, the effect of atomic interactions has so far remained largely unexplored. Here, we realize a Su-Schrieffer-Heeger model in the momentum lattice of a Bose-Einstein condensate with tunable atomic interactions and measure the bulk dynamics of atoms in a synthetic topological wire subjected to sudden quench under various interactions. We observe the breakdown of chiral dynamics in the atomic wire with increasing strength of interaction, where the atoms are localized at the initial injection site under the strong interaction. We show that the mean chiral displacement can be used to characterize the effect of interaction on the atomic chiral dynamics by studying its variation with the interaction. Our results provide a benchmark for exploring the interacting topological fluids.