Statistics-controlled topological phases in a Su-Schrieffer-Heeger ladder

Abstract

In strictly one-dimensional lattices, free fermions and hard-core bosons exhibit equivalent physical properties in many-particle systems. However, this statistical equivalence generally breaks down upon moving to higher dimensions. Our work investigates the significant effects of this difference on the topological phase transition in a minimal system lying away from one dimension: the two-leg Su-Schrieffer-Heeger (SSH) ladder. Starting in the limit of two decoupled SSH chains having opposite hopping dimerization patterns (staggered dimerization), we demonstrate that introducing inter-leg coupling drives a transition from a topological to a trivial phase for both spinless fermions and hard-core bosons. However, the topological to trivial phase transition boundary is strongly sensitive to the underlying particle statistics. We find that this intriguing effect favors a trivial phase sandwiched between the two topological phases with opposite characters for the case of hard-core bosons, resulting in a reentrant topological phase transition. In contrast, this reentrant phenomenon is absent for spinless fermions, with the topological phases being separated by a gapless line instead of an intervening trivial phase. This study demonstrates the interplay between particle statistics and topological features, revealing fundamentally different properties in an experimentally accessible set-up.