Interaction-induced topological bound states and Thouless pumping in a one-dimensional optical lattice

TL;DR

This paper explores how interactions induce topological bound states and enable Thouless pumping in a one-dimensional optical lattice, revealing new topological phenomena driven by particle interactions and symmetry protections.

Contribution

It introduces the concept of center-of-mass Zak phase for interacting particles and demonstrates interaction-induced topological bound states and their Thouless pumping.

Findings

Topological bound states appear due to interactions and are protected by symmetry.

Interaction is essential; systems become trivial without it.

Quantized center-of-mass shift achieved via topological Thouless pumping.

Abstract

We study topological features of interacting spin- 1 2 particles in one-dimensional state-dependent optical lattices. Due to the co-translational symmetry, we introduce the center-of-mass Zak phase with the help of center-of-mass momentum. There appear topological bound states composed by two particles in different spin states via tuning hopping and interaction strengths. Under symmetric open boundary conditions, topological edge bound-states appear as a result of the non-trivial center-ofmass Zak phase of bound-state band, which is protected by the center-of-mass inversion symmetry. The interaction plays a crucial role in the appearance of topological bound states and the system becomes completely trivial if the interaction is switched off. By periodically modulating the hopping and interaction strengths, we show how to implement topological Thouless pumping of bound states, in which the quantized shift of center-of-mass can be described by a non-trivial center-of-mass Chern number.