Fate of topological character of an SSH ladder in the many-body limit

The Su-Schrieffer-Heeger (SSH) model in one dimension is known to exhibit a topological phase transition (TPT) as a function of hopping dimerization via a gap-closing point. It has been shown that when two such chains form a ladder, if the dimerization patterns coincide between the two chains, the TPT disappears due to hybridization. However, if the patterns are staggered, the TPT persists and the system also allows for a trivial phase. Here, we focus on the behavior of hardcore bosons in such ladder systems. Starting from the single-particle energy spectrum for both the dimerization patterns, we discuss the non-interacting phase diagrams in the many-body limit. Then we perform an analysis of interaction effects, with the prime focus being on the staggered configuration, where the attractive or repulsive nature of the interaction influences the topological critical point. Finally, as an experimentally relevant quantity, we present the behavior of interaction-induced topological charge pumping.