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Non-Hermitian systems exhibit a fundamental spectral dichotomy absent in Hermitian physics: the eigenvalue spectrum and the eigenstate spectrum can deviate significantly in the thermodynamic limit. We explain how non-Hermitian Hamiltonians…

Mesoscale and Nanoscale Physics · Physics 2026-01-09 Lucien Jezequel , Loïc Herviou , Jens Bardarson

In this paper, we systematically investigate the impurity-induced bound states in 1D non-Hermitian systems. By establishing an exact relationship between impurity potential and bound-state energy, we determine the minimum impurity potential…

Mesoscale and Nanoscale Physics · Physics 2023-10-30 Zixi Fang , Chen Fang , Kai Zhang

In a Hermitian system, bound states must have quantized energies, whereas extended states can form a continuum. We demonstrate how this principle fails for non-Hermitian systems, by analyzing non-Hermitian continuous Hamiltonians with an…

Quantum Physics · Physics 2023-03-29 Qiang Wang , Changyan Zhu , Xu Zheng , Haoran Xue , Baile Zhang , Y. D. Chong

The hallmark of symmetry-protected topological (SPT) phases is the existence of anomalous boundary states, which can only be realized with the corresponding bulk system. In this work, we show that for every Hermitian anomalous boundary mode…

Mesoscale and Nanoscale Physics · Physics 2019-11-20 Jong Yeon Lee , Junyeong Ahn , Hengyun Zhou , Ashvin Vishwanath

The Hatano-Nelson model is one of the most prototypical non-Hermitian models that exhibit the intrinsic non-Hermitian topological phases and the concomitant skin effect. These phenomena unique to non-Hermitian topological systems originate…

Strongly Correlated Electrons · Physics 2023-09-19 Taozhi Guo , Kohei Kawabata , Ryota Nakai , Shinsei Ryu

We develop a systematically general theory of one-dimensional (1D) non-Hermitian systems, elaborating on the energy bands, the band degeneracy, and the defectiveness of eigenstates under open boundary conditions. We analyze the band…

Mesoscale and Nanoscale Physics · Physics 2022-02-22 Yongxu Fu , Shaolong Wan

In this paper, we construct a generating function quadratic at infinity for any exact Lagrangian in $\mathbb R^{2n}$ that equals $\mathbb R^n$ outside a compact set. Such a Lagrangian may be viewed as a Lagrangian filling of the standard…

Symplectic Geometry · Mathematics 2026-04-29 Thomas Kragh

This work constructs a hypothesis test for detecting whether an data-generating function $h: R^p \rightarrow R$ belongs to a specific reproducing kernel Hilbert space $\mathcal{H}_0$ , where the structure of $\mathcal{H}_0$ is only…

Machine Learning · Statistics 2017-10-31 Jeremiah Zhe Liu , Brent Coull

Both the physics and applications of fermionic symmetry-protected topological phases rely heavily on a principle known as bulk-boundary correspondence, which predicts the emergence of protected boundary-localized energy excitations…

Statistical Mechanics · Physics 2023-04-10 Abhijeet Alase , Emilio Cobanera , Gerardo Ortiz , Lorenza Viola

We show that a non-Hermitian lattice with a disclination can host topological disclination states that are induced by on-site gain and loss. The disclination states are inherently non-Hermitian as they do not exist in the limit of zero…

Mesoscale and Nanoscale Physics · Physics 2024-06-06 Rimi Banerjee , Subhaskar Mandal , Yun Yong Terh , Shuxin Lin , Gui-Geng Liu , Baile Zhang , Y. D. Chong

Recently, a one-to-one correspondence between non-trivial non-Hermitian topology and directional amplification has been demonstrated, theoretically and experimentally, for the case of one complex band. Here, we extend our framework to…

Mesoscale and Nanoscale Physics · Physics 2025-09-25 Clara C. Wanjura , Andreas Nunnenkamp

We investigate the interplay between the non-Hermitian skin effect (NHSE), parity-time (PT) symmetry, and topological defect states in a finite non-Hermitian Su-Schrieffer-Heeger (SSH) chain. In the conventional NHSE regime, non-reciprocal…

Mesoscale and Nanoscale Physics · Physics 2025-05-28 S. M. Rafi-Ul-Islam , Zhuo Bin Siu , Md Saddam Hossain Razo , Mansoor B. A. Jalil

The non-Hermitian skin effect (NHSE), characterized by a macroscopic accumulation of eigenstates at the edge of a system with open boundaries, is often ascribed to a non-trivial point-gap topology of the Bloch Hamiltonian. We revisit this…

Statistical Mechanics · Physics 2026-04-07 J. Sirker

This article considers the generative modeling of the (mixed) states of quantum systems, and an approach based on denoising diffusion model is proposed. The key contribution is an algorithmic innovation that respects the physical nature of…

Quantum Physics · Physics 2024-05-28 Yuchen Zhu , Tianrong Chen , Evangelos A. Theodorou , Xie Chen , Molei Tao

We study spaces of modelled distributions with singular behaviour near the boundary of a domain that, in the context of the theory of regularity structures, allow one to give robust solution theories for singular stochastic PDEs with…

Probability · Mathematics 2019-04-09 Máté Gerencsér , Martin Hairer

We examine the formation of bound states on a generalized nonlinear impurity located at or near the beginning (surface) of a linear, tight-binding semi-infinite lattice. Using the formalism of lattice Green functions, we obtain in closed…

Disordered Systems and Neural Networks · Physics 2009-11-10 M. I. Molina

We consider restricted Boltzmann machines with a binary visible layer and a Gaussian hidden layer trained by an unlabelled dataset composed of noisy realizations of a single ground pattern. We develop a statistical mechanics framework to…

Disordered Systems and Neural Networks · Physics 2024-06-17 Alberto Fachechi , Elena Agliari , Miriam Aquaro , Anthony Coolen , Menno Mulder

Genuinely non-Hermitian topological phases can be realized in open systems with sufficiently strong gain and loss; in such phases, the Hamiltonian cannot be deformed into a gapped Hermitian Hamiltonian without energy bands touching each…

Mesoscale and Nanoscale Physics · Physics 2021-06-02 Heinrich-Gregor Zirnstein , Gil Refael , Bernd Rosenow

Recent experimental advances in controlling dissipation have brought about unprecedented flexibility in engineering non-Hermitian Hamiltonians in open classical and quantum systems. A particular interest centers on the topological…

Mesoscale and Nanoscale Physics · Physics 2018-09-25 Zongping Gong , Yuto Ashida , Kohei Kawabata , Kazuaki Takasan , Sho Higashikawa , Masahito Ueda

We compute exactly the generating function of a supersymmetric non-linear sigma model describ-ing random matrices belonging to the unitary class. Although an arbitrary source explicitly breaksthe supersymmetry, a careful analysis of the…

High Energy Physics - Theory · Physics 2025-07-10 Adam Rançon , Ivan Balog