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We reveal a novel topological property of the exceptional points in a two-level parity-time symmetric system and then propose a scheme to detect the topological exceptional points in the system, which is embedded in a larger Hilbert space…

Quantum Physics · Physics 2017-08-02 Jian Xu , Yan-Xiong Du , Wei Huang , Dan-Wei Zhang

We study topological properties of one-dimensional non-Hermitian systems without chiral symmetry and give phase diagrams characterized by topological invariants $\nu_E$ and $\nu_{total}$, associated with complex energy vorticity and…

Mesoscale and Nanoscale Physics · Physics 2018-11-16 Hui Jiang , Chao Yang , Shu Chen

The need for large amounts of training data in modern machine learning is one of the biggest challenges of the field. Compared to the brain, current artificial algorithms are much less capable of learning invariance transformations and…

Neural and Evolutionary Computing · Computer Science 2023-07-25 Aleksandar Vučković , Benedikt Stock , Alexander V. Hopp , Mathias Winkel , Helmut Linde

Understanding the interplay of non-Hermiticity and topology is crucial given the intrinsic openness of most natural and engineered systems and it has important ramifications in topological lasers and sensors. Intense efforts have been…

The emergence of the non-Hermitian skin effect, distinguished by the exponential localization of bulk states onto boundaries in open systems, has redefined the conventional band theory. It can be established through the generalized…

Other Condensed Matter · Physics 2026-05-19 Jiuchun Meng , Lichao Sun , Xiumei Wang , Dandan Zhu , Xingping Zhou

Non-Hermitian physics predicts open quantum system dynamics with unique topological features such as exceptional points and the non-Hermitian skin effect. We show that this new paradigm of topological systems can serve as probes for bulk…

Quantum Physics · Physics 2024-08-28 Saubhik Sarkar , Francesco Ciccarello , Angelo Carollo , Abolfazl Bayat

Non-Hermitian topological phases in static and periodically driven systems have attracted great attention in recent years. Finding dynamical probes for these exotic phases would be of great importance in the detection and application of…

Mesoscale and Nanoscale Physics · Physics 2020-03-17 Longwen Zhou

By studying the topological invariance andBerry phase in non-Hermitian systems, we reveal the basic properties of the complex Berry phase and generalize the global Berry phases Q to identify the topological invariance for non-Hermitian…

Quantum Physics · Physics 2015-02-03 Shi-Dong Liang , Guang-Yao Huang

Multi-band insulating Bloch Hamiltonians with internal or spatial symmetries, such as particle-hole or inversion, may have topologically disconnected sectors of trivial atomic-limit (momentum-independent) Hamiltonians. We present a…

Disordered Systems and Neural Networks · Physics 2021-04-19 Oleksandr Balabanov , Mats Granath

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…

Non-Hermitian systems offer new platforms for unusual physical properties that can be flexibly manipulated by redistribution of the real and imaginary parts of refractive indices, whose presence breaks conventional wave propagation…

Optics · Physics 2022-04-29 W. W. Ahmed , M. Farhat , K. Staliunas , X. Zhang , Y. Wu

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

This paper extends the property of interlacing of the zeros of eigenfunctions in Hermitian systems to the topological property of winding number in non-Hermitian systems. Just as the number of nodes of each eigenfunction in a self-adjoint…

Mathematical Physics · Physics 2018-01-17 Stella T. Schindler , Carl M. Bender

We report an experimental demonstration of a machine learning approach to identify exotic topological phases, with a focus on the three-dimensional chiral topological insulators. We show that the convolutional neural networks---a class of…

Artificial neural networks and machine learning have now reached a new era after several decades of improvement where applications are to explode in many fields of science, industry, and technology. Here, we use artificial neural networks…

Disordered Systems and Neural Networks · Physics 2017-11-23 Dong-Ling Deng , Xiaopeng Li , S. Das Sarma

The fundamental concept underlying topological phenomena posits the geometric phase associated with eigenstates. In contrast to this prevailing notion, theoretical studies on time-varying Hamiltonians allow for a new type of topological…

Quantum Physics · Physics 2025-11-27 Pengfei Lu , Yang Liu , Qifeng Lao , Teng Liu , Xinxin Rao , Ji Bian , Hao Wu , Feng Zhu , Le Luo

Identifying phase boundaries of interacting systems is one of the key steps to understanding quantum many-body models. The development of various numerical and analytical methods has allowed exploring the phase diagrams of many Hermitian…

Quantum Physics · Physics 2024-02-08 Sharareh Sayyad , Jose L. Lado

The synergy between non-Hermitian concepts and topological ideas have led to very fruitful activity in the recent years. Their interplay has resulted in a wide variety of new non-Hermitian topological phenomena being discovered. In this…

Mesoscale and Nanoscale Physics · Physics 2023-06-16 Ayan Banerjee , Ronika Sarkar , Soumi Dey , Awadhesh Narayan

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

The non-Hermiticity of the system gives rise to a distinct knot topology in the complex eigenvalue spectrum, which has no counterpart in Hermitian systems. In contrast, the singular values of a non-Hermitian (NH) Hamiltonian are always real…

Quantum Physics · Physics 2026-04-06 Gaurav Hajong , Ranjan Modak , Bhabani Prasad Mandal