Inter-species topological phases via a dynamical gauge field

We uncover a class of inter-species topological phases in a one-dimensional lattice, loaded with two species of non-identical particles interacting via a dynamical gauge field (DGF). Two types of topological states are found to emerge from different inter-species topology activated by the DGF. Specifically, edge confined states with co-localization of both species arise from an extrinsic inter-species topology, which can be decomposed into the single-particle topology for each species. On the other hand, bulk-bound states with extended distribution emerge from an intrinsic inter-species topology that cannot be understood from single-particle ones. The two classes of inter-species topology are found to be independent of each other, characterized by different sets of inter-species topological invariants. Thus, their topological states can coexist in certain parameter regimes and compete with each other, leading to distinguished dynamical signatures. We further propose a feasible cold-atom realization of our model to demonstrate experimental accessibility of inter-species topological phases. Our work establishes inter-species topology as a new organizing principle of topological matter, revealing how correlations between distinct particle species can generate topological phenomena beyond single-particle paradigms.