Observation of Robust Zero Energy Extended States

TL;DR

This paper demonstrates the existence of robust, disorder-resistant extended states within the bulk of a one-dimensional system using lossy coupled resonators, revealing a new form of topologically protected transport beyond boundary states.

Contribution

It introduces the experimental and theoretical observation of bulk extended states with topological robustness in a 1D system, expanding the understanding of topological transport phenomena.

Findings

Robust bulk states observed in lossy 1D resonator systems

These states resist disorder in coupling and losses

Potential for new robust transport mechanisms beyond edge states

Abstract

Topological edge states arise at the interface of two topologically-distinct structures and have two distinct features: they are localized and robust against symmetry protecting disorder. On the other hand, conventional transport in one dimension is associated with extended states, which typically do not have topological robustness. In this paper, using lossy coupled resonators in one dimension, we demonstrate both theoretically and experimentally the existence of robust states residing in the bulk. We show that they are unusually robust against disorders in coupling between adjacent sites and losses. Our work paves the way to a new form of robust transport that is not limited to boundary phenomena and can be accessed more easily from far field.