Many-Body Bound States in the Continuum

TL;DR

This paper demonstrates the existence of many-body bound states in the continuum within a one-dimensional Bose-Hubbard model, showing they prevent thermalization and extend the concept of BICs to interacting many-particle systems.

Contribution

It provides the first numerical and analytical evidence for many-body BICs in a Bose-Hubbard chain, expanding the understanding of BICs beyond single-particle scenarios.

Findings

Many-body BICs exist in the Bose-Hubbard model with an impurity.

Many-body BICs prevent thermalization from simple initial states.

The results extend BIC concepts to interacting many-particle systems.

Abstract

A bound state in the continuum (BIC) is a spatially bounded energy eigenstate lying in a continuous spectrum of extended eigenstates. While various types of single-particle BICs have been found in the literature, whether or not BICs can exist in genuinely many-body systems remains inconclusive. Here, we provide numerical and analytical pieces of evidence for the existence of many-body BICs in a one-dimensional Bose-Hubbard chain with an attractive impurity potential, which was previously known to host a BIC in the two-particle sector. We also demonstrate that the many-body BICs prevent the system from thermalization when one starts from simple initial states that can be prepared experimentally.