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Recently, many novel and exotic phases have been proposed by considering the role of topology in non-Hermitian systems, and their emergent properties are of wide current interest. In this work we propose the non-Hermitian generalization of…

Mesoscale and Nanoscale Physics · Physics 2021-10-12 Ayan Banerjee , Awadhesh Narayan

We proposed a framework for the topological classification of non-Hermitian systems. Different from previous $K$-theoretical approaches, our approach is a homotopy classification, which enables us to see more topological invariants.…

Mesoscale and Nanoscale Physics · Physics 2022-06-09 Zhi Li , Roger S. K. Mong

Functional brain networks exhibit topological structures that reflect neural organization; however, statistical comparison of these networks is challenging for several reasons. This paper introduces a topologically invariant permutation…

Neurons and Cognition · Quantitative Biology 2025-12-30 Sixtus Dakurah

Non-Hermiticity has widespread applications in quantum physics. It brings about distinct topological phases without Hermitian counterparts, and gives rise to the fundamental challenge of phase classification from both theoretical and…

The Hatano-Nelson and the non-Hermitian Su-Schrieffer-Heeger model are paradigmatic examples of non-Hermitian systems that host non-trivial boundary phenomena. In this work, we use recently developed graph-theoretical tools to design…

Machine learning techniques have been shown to be effective to recognize different phases of matter and produce phase diagrams in the parameter space interested, while they usually require prior labeled data to perform well. Here, we…

We show that many-body fermionic non-Hermitian systems require two distinct sets of topological invariants to describe the topology of energy bands and quantum states respectively, with the latter yet to be explored. We identify 10 symmetry…

Quantum Physics · Physics 2024-04-30 Kui Cao , Su-Peng Kou

Non-Hermitian systems can exhibit unique topological and localization properties. Here we elucidate the non-Hermitian effects on disordered topological systems by studying a non-Hermitian disordered Su-Schrieffer-Heeger model with…

Quantum Physics · Physics 2020-04-15 Dan-Wei Zhang , Ling-Zhi Tang , Li-Jun Lang , Hui Yan , Shi-Liang Zhu

Recent years have seen a growing interest in topological phases beyond the standard paradigm of gapped, isolated systems. One recent direction is to explore topological features in non-hermitian systems that are commonly used as effective…

Mesoscale and Nanoscale Physics · Physics 2026-02-03 Carlos Ortega-Taberner , Maria Hermanns

The continuous effort towards topological quantum devices calls for an efficient and non-invasive method to assess the conformity of components in different topological phases. Here, we show that machine learning paves the way towards…

Disordered Systems and Neural Networks · Physics 2019-01-24 Marcello D. Caio , Marco Caccin , Paul Baireuther , Timo Hyart , Michel Fruchart

We revisit the problem of classifying topological band structures in non-Hermitian systems. Recently, a solution has been proposed, which is based on redefining the notion of energy band gap in two different ways, leading to the so-called…

Mathematical Physics · Physics 2020-05-20 Charles C. Wojcik , Xiao-Qi Sun , Tomáš Bzdušek , Shanhui Fan

Non-Hermiticity gives rise to unique topological phases that have no counterparts in Hermitian systems. Such intrinsic non-Hermitian topological phases appear even in one dimension while no topological phases appear in one-dimensional…

Strongly Correlated Electrons · Physics 2022-04-20 Kohei Kawabata , Ken Shiozaki , Shinsei Ryu

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

Topological phases have recently witnessed a rapid progress in non-Hermitian systems. Here we study a one-dimensional non-Hermitian Aubry-Andr\'e-Harper model with imaginary periodic or quasiperiodic modulations. We demonstrate that the…

Mesoscale and Nanoscale Physics · Physics 2020-06-11 Qi-Bo Zeng , Yan-Bin Yang , Yong Xu

Non-Hermiticity gives rise to unique topological phases without Hermitian analogs. However, the effective field theory has yet to be established. Here, we develop a field-theoretical description of the intrinsic non-Hermitian topological…

Mesoscale and Nanoscale Physics · Physics 2021-06-01 Kohei Kawabata , Ken Shiozaki , Shinsei Ryu

Topological phase transitions, which do not adhere to Landau's phenomenological model (i.e. a spontaneous symmetry breaking process and vanishing local order parameters) have been actively researched in condensed matter physics. Machine…

Mesoscale and Nanoscale Physics · Physics 2021-03-03 Alexander Kerr , Geo Jose , Colin Riggert , Kieran Mullen

We numerically verify and analytically prove a winding number invariant that correctly predicts the number of edge states in one-dimensional, nearest-neighbor (between unit cells), two-band models with any complex couplings and open…

Mesoscale and Nanoscale Physics · Physics 2025-05-28 Janet Zhong , Heming Wang , Alexander N Poddubny , Shanhui Fan

We develop the topological band theory for systems described by non-Hermitian Hamiltonians, whose energy spectra are generally complex. After generalizing the notion of gapped band structures to the non-Hermitian case, we classify "gapped"…

Mesoscale and Nanoscale Physics · Physics 2018-04-11 Huitao Shen , Bo Zhen , Liang Fu

Non-Hermitian theory is a theoretical framework that excels at describing open systems. It offers a powerful tool in the characterization of both the intrinsic degrees of freedom (DOFs) of a system and the interactions with the external…

Quantum Physics · Physics 2024-05-28 Kun Ding , Chen Fang , Guancong Ma

Machine-learning driven models have proven to be powerful tools for the identification of phases of matter. In particular, unsupervised methods hold the promise to help discover new phases of matter without the need for any prior…