近日，墨西哥José A. Medina-Vázquez课题组探究了不对称长程相互作用对光子高阶拓扑绝缘体角态的影响。相关研究成果已于2023年4月12日在国际学术期刊《物理评论A》上发表。

该研究将类型III角态的概念引入光子体系中，揭示了它们的存在取决于光子晶格中的长程相互作用（LRI）。研究人员通过考虑方形晶格中各种次近邻跳跃和描述系统的哈密顿量中细胞间次近邻跳跃项的不对称耦合，在具有不对称耦合的扩展二维Su-Schrieffer-Heeger（SSH）模型中扩展了SSH模型。随后，研究人员在解析紧束缚模型中识别了类型I、类型II和类型III角态，并揭示了类型II和类型III角态与边缘态分离的情况。

基于这些结果，研究人员提出了一个模拟不对称耦合的光子模型，并在其中发现了类型II和类型III角态的存在。该研究扩展了人们对光子体系中拓扑角态的认识，并强调了LRI在产生拓扑受限模式中的重要作用。

据悉，将长程相互作用（LRI）引入描述拓扑系统的模型中，揭示了以前未知的拓扑相和状态。最近的研究表明，在高阶拓扑绝缘体中，通过考虑通过次近邻跳跃引入LRI，发现了非传统的受限角态。然而，在光子学领域中，这些角态的研究仍然有限。

附：英文原文

Title: Influence of asymmetric long-range interactions on corner states in photonic higher-order topological insulators

Author: José A. Medina-Vázquez

Issue&Volume: 2023/04/12

Abstract: The introduction of long-range interaction (LRI) in models that describe topological systems has unveiled previously unknown topological phases and states. Recently, in higher-order topological insulators, consideration of LRI via next-nearest-neighbor (NNN) hopping led to the discovery of unconventional confined corner states; however, their study is still limited in photonic prospects. In this paper, we bring the concept of type-III corner states into the photonic regime and reveal that their existence depends on LRI in photonic lattices, mimicking an extended two-dimensional Su-Schrieffer-Heeger (SSH) model with an asymmetric coupling. The extension of the SSH model is performed by considering a variety of NNN hopping in square lattices, and an asymmetry coupling in the intercellular NNN hopping terms of the Hamiltonian describing the system. Subsequently, we identify type-I, type-II, and type-III corner states in the analytical tight-binding model, revealing that the type-II and type-III corner states are split from the edge states. Based on the obtained results, we propose a photonic model that mimics the asymmetric coupling and find the existence of type-II and type-III corner states in the photonic model. The results presented here extend the knowledge we have about topological corner states in photonic systems and highlight the role played by LRIs in the generation of topological confined modes.

DOI: 10.1103/PhysRevA.107.043503

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.107.043503