Multi-particle Wannier states and Thouless pumping of interacting bosons

TL;DR

This paper introduces multi-particle Wannier states for interacting bosons, linking their shift to topological invariants, and demonstrates novel topological pumping phenomena in an interacting Rice-Mele model.

Contribution

It develops a new framework for understanding multi-particle topological effects in interacting systems and explores their dynamic properties.

Findings

Identification of multi-particle Wannier states and their relation to Chern numbers

Observation of bound-state Thouless pumping of two bosons

Discovery of topologically resonant tunneling phenomena

Abstract

The study of topological effects in physics is a hot area, and only recently researchers were able to address the important issues of topological properties of interacting quantum systems. But it is still a great challenge to describe multi-particle and interaction effects. Here, we introduce multi-particle Wannier states for interacting systems with co-translational symmetry. We reveal how the shift of multi-particle Wannier state relates to the multi-particle Chern number, and study the two-boson Thouless pumping in an interacting Rice-Mele model. In addition to the bound-state Thouless pumping in which two bosons move unidirectionally as a whole, we find topologically resonant tunneling in which two bosons move unidirectionally, one by the other, provided the neighboring-well potential bias matches the interaction energy. Our work creates a new paradigm for multi-particle topological effects and lays a cornerstone for detecting interacting topological states.