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The classification of point gap topology in all local non-Hermitian symmetry classes has been recently established. However, many entries in the resulting periodic table have only been discussed in a formal setting and still lack a physical…

Mesoscale and Nanoscale Physics · Physics 2023-09-04 M. Michael Denner , Titus Neupert , Frank Schindler

Nonlinearity and non-Hermiticity, for example due to environmental gain-loss processes, are a common occurrence throughout numerous areas of science and lie at the root of many remarkable phenomena. For the latter, parity-time-reflection…

Biological Physics · Physics 2025-04-03 Alexander Felski , Flore K. Kunst

We investigate the emergence of unconventional corner mode in a two-dimensional topolectrical circuits induced by asymmetric couplings. The non-Hermitian skin effect of two kinked one-dimensional lattices with multiple asymmetric couplings…

Mesoscale and Nanoscale Physics · Physics 2024-02-22 Hengxuan Jiang , Xiumei Wang , Jie Chen , Xingping Zhou

We investigate the topological properties of multiple exceptional points in non-Hermitian two-level systems, emphasizing vorticity as a topological invariant arising from complex energy structures. We categorize EP pairs as fundamental…

Optics · Physics 2025-12-19 Jung-Wan Ryu , Chang-Hwan Yi , Jae-Ho Han

We report on the measurement of topological invariants in an electromagnetic topological insulator analog formed by a microwave network, consisting of the winding numbers of scattering matrix eigenvalues. The experiment can be regarded as a…

We develop perturbative methods to study and control dynamical phenomena related to exceptional points in Non-Hermitian systems. In particular, we show how to find perturbative solutions based on the Magnus expansion that accurately…

Quantum Physics · Physics 2021-11-23 Hugo Ribeiro , Florian Marquardt

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

We discover novel topological pumps in the Josephson effects for superconductors. The phase difference, which is odd under the chiral symmetry defined by the product of time-reversal and particle-hole symmetries, acts as an anomalous…

Superconductivity · Physics 2014-07-11 Fan Zhang , C. L. Kane

The non-Hermitian dynamics of open systems deal with how intricate coherent effects of a closed system intertwine with the impact of coupling to an environment. The system-environment dynamics can then lead to so-called exceptional points,…

Strongly Correlated Electrons · Physics 2022-09-12 Andisheh Khedri , Dominic Horn , Oded Zilberberg

We provide classification of gapless phases in non-Hermitian systems according to two types of complex-energy gaps: point gap and line gap. We show that exceptional points, at which not only eigenenergies but also eigenstates coalesce, are…

Mesoscale and Nanoscale Physics · Physics 2020-04-22 Takumi Bessho , Kohei Kawabata , Masatoshi Sato

Exceptional points play a pivotal role in the topology of non-Hermitian systems, and significant advances have been made in classifying exceptional points and exploring the associated phenomena. Exceptional surfaces, which are hypersurfaces…

Materials Science · Physics 2022-09-08 Hongwei Jia , Ruo-Yang Zhang , Jing Hu , Yixin Xiao , Yifei Zhu , C. T. Chan

Topological pumping refers to transfer of a physical quantity governed by the systemtopology, resulting in quantized amounts of the transferred quantities. It is a ubiqui-tous wave phenomenon typically considered subject to exactly periodic…

The most intriguing properties of non-Hermitian systems are found near the exceptional points (EPs) at which the Hamiltonian matrix becomes defective. Due to the complex topological structure of the energy Riemann surfaces close to an EP…

Classical Physics · Physics 2018-06-19 Xu-Lin Zhang , Shubo Wang , Bo Hou , C. T. Chan

We investigate the rich physics of photonic molecule lasers using a non-Hermitian dimer model. We show that several interesting features, predicted recently using a rigorous steady state ab-initio laser theory (SALT), can be captured by…

Optics · Physics 2015-06-19 Ramy El-Ganainy , Mercedeh Khajavikhan , Li Ge

Topological materials exhibit edge-localized scattering-free modes protected by their nontrivial bulk topology through the bulk-edge correspondence in Hermitian systems. While topological phenomena have recently been much investigated in…

Mesoscale and Nanoscale Physics · Physics 2020-11-16 Kazuki Sone , Yuto Ashida , Takahiro Sagawa

By means of time-dependent density matrix renormalization group calculations we study topological quantum pumping in a strongly interacting system. The system under consideration is described by the Hamiltonian of a one-dimensional extended…

Strongly Correlated Electrons · Physics 2013-02-26 Davide Rossini , Marco Gibertini , Vittorio Giovannetti , Rosario Fazio

A Thouless pump can be regarded as a dynamical version of the integer quantum Hall effect. In a finite-size configuration, such topological pump displays edge modes that emerge dynamically from one bulk-band and dive into the opposite…

Mesoscale and Nanoscale Physics · Physics 2020-11-24 Wenting Cheng , Emil Prodan , Camelia Prodan

Exceptional points (EPs) are non-Hermitian degeneracies, where both eigenvalues and eigenvectors coalesce, which are fundamentally distinct from their Hermitian counterparts. In this study, we investigate the influence of hexagonal warping…

Mesoscale and Nanoscale Physics · Physics 2026-01-13 Md Afsar Reja , Awadhesh Narayan

Exceptional points in non-Hermitian systems have recently been shown to possess nontrivial topological properties, and to give rise to many exotic physical phenomena. However, most studies thus far have focused on isolated exceptional…

Optics · Physics 2019-02-21 Hengyun Zhou , Jong Yeon Lee , Shang Liu , Bo Zhen

We show the existence of non-Hermitian degeneracies, known as exceptional points, in the collective mode spectrum of Fermi liquids with quadrupolar interactions. Through a careful analysis of the analytic properties of the dynamic…

Strongly Correlated Electrons · Physics 2020-11-26 Rui Aquino , Daniel G. Barci