Boundary-localized many-body bound states in the continuum

TL;DR

This paper introduces a new type of many-body bound states in the continuum localized at boundaries, induced solely by uniform onsite interactions, demonstrated through numerical and experimental simulations.

Contribution

It reveals boundary-localized many-body BICs in homogeneous systems without impurity design, expanding understanding of correlated BICs beyond single-particle physics.

Findings

Three or more interacting bosons localize at the boundary

Multi-boson eigenstates embed within the continuum spectrum

Experimental simulation using nonlinear circuit networks

Abstract

Bound states in the continuum (BICs), referring to spatially localized bound states with energies falling within the range of extended modes, have been extensively investigated in single-particle systems, leading to diverse applications in photonics, acoustics, and other classical-wave systems. Recently, there has been theoretical interest in exploring many-body BICs in interacting quantum systems, which necessitate the careful design of impurity potentials or spatial profiles of interaction. Here, we propose a type of many-body BICs localized at boundaries, which can be purely induced by the uniform onsite interaction without requiring any specific design of impurity potential or nonlocal interaction. We numerically show that three or more interacting bosons can concentrate on the boundary of a homogeneous one-dimensional lattice, which is absent at single- and twoparticle counterparts. Moreover, the eigenenergy of multi-boson bound states can embed within the continuous energy spectra of extended scattering states, thereby giving rise to interactioninduced boundary many-body BICs. Furthermore, by mapping Fock states of three and four bosons to nonlinear circuit networks, we experimentally simulate boundary many-body BICs. Our findings enrich the comprehension of correlated BICs beyond the single-particle level, and have the potential to inspire future investigations on exploring many-body BICs.