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We study a non-Hermitian generalization of strongly correlated quantum systems in which the transfer energy of electrons is asymmetric. It is known that a non-Hermitian critical point is equal to the inverse localization length of a…

Strongly Correlated Electrons · Physics 2007-05-23 Yuichi Nakamura , Naomichi Hatano

Real-valued band structures are foundational to analyzing periodic systems within the Hermitian description and have been experimentally well-established over recent decades. In contrast, non-Hermitian systems exhibit complex band…

Quantum Physics · Physics 2025-10-24 Jia-Xin Zhong , Jing Lin , Kai Chen , Jing Lu , Kun Ding , Yun Jing

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

Recently, the search for topological states of matter has turned to non-Hermitian systems, which exhibit a rich variety of unique properties without Hermitian counterparts. Lattices modeled through non-Hermitian Hamiltonians appear in the…

Mesoscale and Nanoscale Physics · Physics 2019-01-21 V. M. Martinez Alvarez , J. E. Barrios Vargas , M. Berdakin , L. E. F. Foa Torres

We study the many-body physics of different quantum systems using a hierarchy of correlations, which corresponds to a generalization of the $1/\mathcal{Z}$ hierarchy. The decoupling scheme obtained from this hierarchy is adapted to…

Strongly Correlated Electrons · Physics 2016-07-27 Álvaro Gómez-León

We present a systematic study of statistical mechanics for non-Hermitian quantum systems. Our work reveals that the stability of a non-Hermitian system necessitates the existence of a single path-dependent conserved quantity, which, in…

Statistical Mechanics · Physics 2023-12-04 Kui Cao , Su-Peng Kou

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

Non-Hermitian quantum systems exhibit fascinating characteristics such as non-Hermitian topological phenomena and skin effect, yet their studies are limited by the intrinsic difficulties associated with their eigenvalue problems, especially…

Mesoscale and Nanoscale Physics · Physics 2024-01-23 Guang Yang , Yongkang Li , Yongxu Fu , Zhenduo Wang , Yi Zhang

We study a topological band degeneracy in non-Hermitian systems with parity-time ($PT$) and parity-particle-hole ($CP$) symmetries. In $d$-dimensional non-Hermitian systems, it is shown that $(d-1)$-dimensional exceptional surfaces can…

Mesoscale and Nanoscale Physics · Physics 2019-01-30 Ryo Okugawa , Takehito Yokoyama

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

Quantum correlations, both spatial and temporal, are the central pillars of quantum mechanics. Over the last two decades, a big breakthrough in quantum physics is its complex extension to the non-Hermitian realm, and dizzying varieties of…

The interplay of topological electronic band structures and strong interparticle interactions provides a promising path towards the constructive design of robust, long-range entangled many-body systems. As a prototype for such systems, we…

Strongly Correlated Electrons · Physics 2025-02-19 Steffen Bollmann , Chandan Setty , Urban F. P. Seifert , Elio J. König

We study the properties of the entanglement spectrum in gapped non-interacting non-Hermitian systems, and its relation to the topological properties of the system Hamiltonian. Two different families of entanglement Hamiltonians can be…

Mesoscale and Nanoscale Physics · Physics 2020-01-06 Loïc Herviou , Nicolas Regnault , Jens H. Bardarson

This topical review article reports rapid progress on the generalization and application of entanglement in non-Hermitian free-fermion quantum systems. We begin by examining the realization of non-Hermitian quantum systems through the…

Quantum Physics · Physics 2026-01-14 Li-Mei Chen , Yao Zhou , Shuai A. Chen , Peng Ye

We show that in a generic, ergodic quantum many-body system the interactions induce a non-trivial topology for an arbitrarily small non-hermitean component of the Hamiltonian. This is due to an exponential-in-system-size proliferation of…

Quantum Physics · Physics 2019-11-06 David J. Luitz , Francesco Piazza

We describe simple quantum-mechanical approach to calculating equilibrium particle current along the edge of a system with non-trivial band spectrum topology. The approach does not require any a priori knowledge of the band topology and, as…

Mesoscale and Nanoscale Physics · Physics 2014-07-23 E. G. Mishchenko , O. A. Starykh

The complex energy bands of non-Hermitian systems braid in momentum space even in one dimension. Here, we reveal that the non-Hermitian braiding underlies the Hermitian topological physics with chiral symmetry under a general framework that…

Mesoscale and Nanoscale Physics · Physics 2023-10-09 W. B. Rui , Y. X. Zhao , Z. D. Wang

Owing to the presence of exceptional points (EPs), non-Hermitian (NH) systems can display intriguing topological phenomena without Hermitian analogs. However, experimental characterizations of exceptional topological invariants have been…

We find that heavy fermion systems can have bulk "Fermi arcs", with the use of the non-Hermitian topological theory. In an interacting electron system, the microscopic many-body Hamiltonian is Hermitian, but the one-body quasiparticle…

Strongly Correlated Electrons · Physics 2020-11-30 Yuki Nagai , Yang Qi , Hiroki Isobe , Vladyslav Kozii , Liang Fu

Band structures of metamaterials described by a nonlinear eigenvalue problem are beyond the existing topological band theory. In this paper, we analyze non-Hermitian topology under the nonlinearity of eigenvalues. Specifically, we elucidate…

Mesoscale and Nanoscale Physics · Physics 2025-02-19 Tsuneya Yoshida , Takuma Isobe , Yasuhiro Hatsugai