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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

We introduce the exceptional topological insulator (ETI), a non-Hermitian topological state of matter that features exotic non-Hermitian surface states which can only exist within the three-dimensional topological bulk embedding. We show…

Mesoscale and Nanoscale Physics · Physics 2021-10-04 M. Michael Denner , Anastasiia Skurativska , Frank Schindler , Mark H. Fischer , Ronny Thomale , Tomáš Bzdušek , Titus Neupert

Pseudo-Hermitian operators generalize the concept of Hermiticity. This class of operators includes the quasi-Hermitian operators, which reformulate quantum theory while retaining real-valued measurement outcomes and unitary time evolution.…

Quantum Physics · Physics 2023-06-08 Jacob L. Barnett

We propose a theoretical scheme to realize the controllable non-Hermitian qubit-qubit coupling by adding a high-loss resonator in tunable coupling superconducting quantum circuit. By changing the effective qubit-qubit coupling, phase and…

Quantum Physics · Physics 2024-12-18 Hui Wang , Yan-Jun Zhao , Xun-Wei Xu

Three dimensional topological superconductors (TScs) protected by time reversal (T) symmetry are characterized by gapless Majorana cones on their surface. Free fermion phases with this symmetry (class DIII) are indexed by an integer n, of…

Strongly Correlated Electrons · Physics 2013-12-03 Lukasz Fidkowski , Xie Chen , Ashvin Vishwanath

Hermitian theories play a major role in understanding the physics of most phenomena. It has been found only in the past decade that non-Hermiticity enables unprecedented effects such as exceptional points, spectral singularities and bulk…

Applied Physics · Physics 2021-10-04 Xiujuan Zhang , Yuan Tian , Jian-Hua Jiang , Ming-Hui Lu , Yan-Feng Chen

Engineering the Hamiltonian of a quantum system is fundamental to the design of quantum systems. Automating Hamiltonian design through gradient-based optimization can dramatically accelerate this process. However, computing the gradients of…

We show that a recent measurement of surface superconductivity in UPt$_3$ (Keller {\it et. al.}, Phys. Rev. Lett. {\bf 73}, 2364 (1994)) can be understood if the superconducting pair wavefunction is suppressed anisotropically at a vacuum to…

Condensed Matter · Physics 2009-10-28 D. F. Agterberg , M. B. Walker

The fidelity susceptibility has been used to detect quantum phase transitions in the Hermitian quantum many-body systems over a decade, where the fidelity susceptibility density approaches $+\infty$ in the thermodynamic limits. Here the…

Quantum Physics · Physics 2021-01-08 Yu-Chin Tzeng , Chia-Yi Ju , Guang-Yin Chen , Wen-Min Huang

Majorana zero modes (MZMs) emerge as edge states in topological superconductors and are promising for topological quantum computation, but their detection has so far been elusive. Here we show that non-Hermiticity can be used to obtain…

Superconductivity · Physics 2023-08-25 R. Arouca , Jorge Cayao , Annica M. Black-Schaffer

In this article, the non-Hermitian characteristics of three-dimensional PT-symmetric coupled electronic resonators are theoretically analyzed. First, the concept of non-Hermitian PT symmetry is illustrated in the context of electronics…

Applied Physics · Physics 2024-11-04 Ke Yin , Kaihao Tang , Lu Tan , Saddam Ibrahim Dawalbait Bakhat , Tianyu Dong , Huacheng Zhu , Yang Yang

We discuss the weak-coupling BCS theory of the heavy fermion superconductor UPt_3, accounting for that system's anisotropic, multisheeted Fermi surface by expanding the order parameter and pair potential in terms of appropriate basis…

Superconductivity · Physics 2007-05-23 G. Haran , P. J. Hirschfeld , M. Sigrist

Non-Hermtian (NH) Hamiltonians effectively describing the physics of dissipative systems have become an important tool with applications ranging from classical meta-materials to quantum many-body systems. Exceptional points, the NH…

Strongly Correlated Electrons · Physics 2021-09-22 Lorenzo Crippa , Jan Carl Budich , Giorgio Sangiovanni

Systems exhibiting degeneracies known as exceptional points have remarkable properties with powerful applications, particularly in sensor design. These degeneracies are formed when eigenstates coincide, and the remarkable effects are…

Analysis of PDEs · Mathematics 2020-08-04 Habib Ammari , Bryn Davies , Erik Orvehed Hiltunen , Hyundae Lee , Sanghyeon Yu

We study non-Hermitian Josephson junctions formed by superconductors with a finite phase difference under non-Hermiticity, which naturally appears due to coupling to normal reservoirs. Depending on the structure of non-Hermiticity, captured…

Superconductivity · Physics 2024-11-13 Jorge Cayao , Masatoshi Sato

Quantum computers have long been anticipated to excel in simulating quantum many-body physics. While most previous work has focused on Hermitian physics, we demonstrate the power of variational quantum circuits for resource-efficient…

Quantum Physics · Physics 2025-04-15 Yuxuan Zhang , Juan Carrasquilla , Yong Baek Kim

We study a simple model of three-dimensional fermions close to a quadratic band touching point, built from the celebrated Luttinger single-particle Hamiltonian and an attractive contact interaction between the particles. Such a system…

Strongly Correlated Electrons · Physics 2016-05-31 Igor Boettcher , Igor F. Herbut

We study the non-Hermitian skin effect in a three-dimensional system of finitely many subwavelength resonators with an imaginary gauge potential. We introduce a discrete approximation of the eigenmodes and eigenfrequencies of the system in…

Analysis of PDEs · Mathematics 2023-11-20 Habib Ammari , Silvio Barandun , Jinghao Cao , Bryn Davies , Erik Orvehed Hiltunen , Ping Liu

Emergence of exceptional points in two dimensions is one of the remarkable phenomena in non-Hermitian systems. We here elucidate the impacts of symmetry on the non-Hermitian physics. Specifically, we analyze chiral symmetric correlated…

Strongly Correlated Electrons · Physics 2019-03-13 Tsuneya Yoshida , Robert Peters , Norio Kawakami , Yasuhiro Hatsugai

Recent experiments reveal a three-dimensional (3D) Fermi surface with a clear $k_z$ dispersion in infinite-layer nickelates, distinguishing them from their cuprate superconductor counterparts. However, the impact of this difference on the…

Superconductivity · Physics 2025-04-29 Chengliang Xia , Shengjie Zhou , Hanghui Chen