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Topology is central to understanding and engineering materials that display robust physical phenomena immune to imperfections. Different topological phases of matter are characterised by topological invariants. In energy-conserving…

The topology of non-Hermitian systems is drastically shaped by the non-Hermitian skin effect, which leads to the generalized bulk-boundary correspondence and non-Bloch band theory. The essential part in formulations of bulk-boundary…

Mesoscale and Nanoscale Physics · Physics 2019-12-11 Fei Song , Shunyu Yao , Zhong Wang

The accurate determination of non-Hermitian (NH) topological invariants plays a central role in the study of NH topological phases. In this work, we propose a general framework for directly measuring NH topological invariants in…

Quantum Gases · Physics 2025-09-16 Xiao-Dong Lin , Long Zhang

The discovery of novel topological phase advances our knowledge of nature and stimulates the development of applications. In non-Hermitian topological systems, the topology of band touching exceptional points is very important. Here we…

Mesoscale and Nanoscale Physics · Physics 2020-09-23 X. M. Yang , P. Wang , L. Jin , Z. Song

Topological invariants play a key role in the characterization of topological states. Due to the existence of exceptional points, it is a great challenge to detect topological invariants in non-Hermitian systems. We put forward a dynamic…

Quantum Physics · Physics 2020-04-22 Bo Zhu , Yongguan Ke , Honghua Zhong , Chaohong Lee

We unveil the geometrical meaning of winding number and utilize it to characterize the topological phases in one-dimensional chiral non-Hermitian systems. While chiral symmetry ensures the winding number of Hermitian systems being integers,…

Mesoscale and Nanoscale Physics · Physics 2018-05-21 Chuanhao Yin , Hui Jiang , Linhu Li , Rong Lü , Shu Chen

We introduce the concept of super universality in quantum Hall and spin liquids which has emerged from previous studies. It states that all the fundamental features of the quantum Hall effect are generically displayed as general topological…

Strongly Correlated Electrons · Physics 2009-11-11 A. M. M. Pruisken , R. Shankar , Naveen Surendran

Topology plays an important role in non-hermitian systems. How to characterize a non-hermitian topological system under open-boundary conditions(OBCs) is a challenging problem. A one-dimensional(1D) topological invariant defined on a…

Strongly Correlated Electrons · Physics 2023-06-21 ChunChi Liu , LiuHao Li , Jin An

A prominent feature of some one-dimensional non-Hermitian systems is that all right-eigenstates of the non-Hermitian Hamiltonian are localized in one end of the chain. The topological and trivial phases are distinguished by the emergence of…

Mesoscale and Nanoscale Physics · Physics 2019-07-17 Motohiko Ezawa

Non-Hermitian systems as theoretical models of open or dissipative systems exhibit rich novel physical properties and fundamental issues in condensed matter physics.We propose a generalized local-global correspondence between the…

Quantum Physics · Physics 2023-08-11 Annan Fan , Shi-Dong Liang

We examine a non-Hermitian (NH) tight-binding system comprising of two orbitals per unit cell and their electrical circuit analogues. We distinguish the PT-symmetric and non-PT symmetric cases characterised by non-reciprocal nearest…

Mesoscale and Nanoscale Physics · Physics 2024-03-11 Dipendu Halder , Ronny Thomale , Saurabh Basu

In spatially periodic Hermitian systems, such as electronic systems in crystals, the band structure is described by the band theory in terms of the Bloch wave functions, which reproduce energy levels for large systems with open boundaries.…

Mesoscale and Nanoscale Physics · Physics 2019-08-14 Kazuki Yokomizo , Shuichi Murakami

We uncover the very rich graph topology of generic bounded non-Hermitian spectra, distinct from the topology of conventional band invariants and complex spectral winding. The graph configuration of complex spectra are characterized by the…

Mesoscale and Nanoscale Physics · Physics 2023-07-06 Tommy Tai , Ching Hua Lee

The geometric interpretation of (pseudo)spin 1/2 systems on the Bloch sphere has been appreciated across different areas ranging from condensed matter to quantum information and high energy physics. Although similar notions for larger…

Quantum Gases · Physics 2022-06-03 Cameron J. D. Kemp , Nigel R. Cooper , F. Nur Ünal

The non-Bloch topology leads to the emergence of various counter-intuitive phenomena in non-Hermitian systems under the open boundary condition (OBC), which can not find a counterpart in Hermitian systems. However, in the non-Hermitian…

Quantum Physics · Physics 2024-07-29 Yue Zhang , Shuai Li , Yingchao Xu , Rui Tian , Miao Zhang , Hongrong Li , Hong Gao , M. Suhail Zubairy , Fuli Li , Bo Liu

We consider a parameter dependent ensemble of two real random matrices with Gaussian distribution. It describes the transition between the symmetry class of the chiral Gaussian orthogonal ensemble (Cartan class B$|$DI) and the ensemble of…

Mathematical Physics · Physics 2019-02-14 Gernot Akemann , Mario Kieburg , Adam Mielke , Pedro Vidal

Eigenstate coalescence in non-Hermitian systems is widely observed in diverse scientific domains encompassing optics and open quantum systems. Recent investigations have revealed that adiabatic encircling of exceptional points (EPs) leads…

Quantum Physics · Physics 2023-06-13 Jung-Wan Ryu , Jae-Ho Han , Chang-Hwan Yi , Moon Jip Park , Hee Chul Park

The advent of non-Hermitian physics has enriched the plethora of topological phases to include phenomena without Hermitian counterparts. Despite being among the most well-studied uniquely non-Hermitian features, the topological properties…

Mesoscale and Nanoscale Physics · Physics 2025-06-05 Marcus Stålhammar , Lukas Rødland

Non-Hermitian topological systems have attracted a lot of research activities in recent times, both theoretically and experimentally, due to their unique physical properties and association with open quantum systems. We show that modular…

Quantum Physics · Physics 2026-05-29 Saubhik Sarkar , Chiranjib Mukhopadhyay , Abolfazl Bayat

A $d$-dimensional second-order topological insulator (SOTI) can host topologically protected $(d - 2)$-dimensional gapless boundary modes. Here we show that a 2D non-Hermitian SOTI can host zero-energy modes at its corners. In contrast to…

Mesoscale and Nanoscale Physics · Physics 2019-02-27 Tao Liu , Yu-Ran Zhang , Qing Ai , Zongping Gong , Kohei Kawabata , Masahito Ueda , Franco Nori