Three-body bound states in antiferromagnetic spin ladders

TL;DR

This paper predicts and characterizes three-particle bound states in antiferromagnetic spin ladders, revealing genuine three-particle interactions' role in quantum many-body systems, with implications for high-temperature superconductor research.

Contribution

It demonstrates the existence of three-particle bound states in a realistic solid state system due to genuine three-particle interactions, supported by calculations for experimental detection.

Findings

Three-particle bound states are predicted in antiferromagnetic spin ladders.

Genuine three-particle interactions are essential for the formation of these bound states.

The dynamic exchange structure factor is computed for experimental detection.

Abstract

Stable bound quantum states are ubiquitous in nature. Mostly, they result from the interaction of only pairs of particles, so called two-body interactions, even when large complex many-particle structures are formed. We show that three-particle bound states occur in a generic, experimentally accessible solid state system: antiferromagnetic spin ladders, related to high-temperature superconductors. This binding is induced by genuine three-particle interactions; without them there is no bound state. We compute the dynamic exchange structure factor required for the experimental detection of the predicted state by resonant inelastic X-ray scattering for realistic material parameters. Our work enables us to quantify these elusive interactions and unambiguously establishes their effect on the dynamics of the quantum many-particle state.