Robust localized zero-energy modes from locally embedded PT-symmetric defects

TL;DR

This paper introduces a method to generate stable zero-energy modes in trivial topological systems using PT-symmetric defects with gain and loss, enabling robust lasing or absorption.

Contribution

It presents a novel way to induce and control zero-energy modes via PT-symmetric defects, bridging topological physics with practical photonic applications.

Findings

Localized zero-energy states are induced by PT-symmetric defects.

Zero-energy modes emerge when gain-loss contrast exceeds a threshold.

Defect states encounter an exceptional point at the transition.

Abstract

We demonstrate the creation of robust localized zero-energy states that are induced into topologically trivial systems by insertion of a PT-symmetric defect with local gain and loss. A pair of robust localized states induced by the defect turns into zero-energy modes when the gain-loss contrast exceeds a threshold, at which the defect states encounter an exceptional point. Our approach can be used to obtain robust lasing or perfectly absorbing modes in any part of the system.