Drive-induced Non-local Interactions and Topological Bulk Transport of Extended Doublons

TL;DR

This paper demonstrates the experimental creation and observation of topologically protected two-particle states called Doublons in a photonic system, revealing new insights into few-particle topological phenomena with non-local interactions.

Contribution

It introduces a method to realize and study extended Doublons with non-local interactions via periodic driving in a photonic platform, advancing understanding of topological states with few particles.

Findings

Resonant formation of extended Doublons at specific interaction strengths

Observation of topologically protected bulk transport of Doublons

Compatibility of the approach with various experimental platforms

Abstract

The existence of boundary states and their protection against symmetry-preserving perturbations are a hallmark feature of topological systems. While this concept originally emerged in the context of sin-gle-particle phenomena in condensed-matter physics, particle interactions have recently been identi-fied as alternative means to establish topological phases. As a consequence, nonlinear topological insu-lators gained much interest as a model system for many interacting particles. However, as their mean-field model inevitably breaks down for small numbers of particles, to date, topological states composed of only few interacting particles remain experimentally largely unexplored. In our work, we explore the physics of extended interaction-induced two-particle topological states, so-called Dou-blons. We experimentally implement non-local-interactions via non-adiabatic periodic driving and dimensional mapping in an artificial photonic solid. The resonant formation of extended Doublon qua-si-particles at specific local interaction strengths is observed, allowing us to probe the topologically protected motion of these entities through the bulk of the system. Our approach is compatible to a number of established experimental platforms and paves the way for studying topological few-particle phenomena with finite interaction strength.