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The study of topological properties by machine learning approaches has attracted considerable interest recently. Here we propose machine learning the topological invariants that are unique in non-Hermitian systems. Specifically, we train…

Computational Physics · Physics 2021-01-27 Ling-Feng Zhang , Ling-Zhi Tang , Zhi-Hao Huang , Guo-Qing Zhang , Wei Huang , Dan-Wei Zhang

We study non-interacting electrons in disordered materials which exhibit a spectral gap, in each of the ten Altland--Zirnbauer symmetry classes, in all space dimensions. We define an appropriate space of Hamiltonians and a topology on it so…

Mathematical Physics · Physics 2026-05-26 Jui-Hui Chung , Jacob Shapiro

We study a wide class of topological free-fermion systems on a hypercubic lattice in spatial dimensions $d\ge 1$. When the Fermi level lies in a spectral gap or a mobility gap, the topological properties, e.g., the integral quantization of…

Mathematical Physics · Physics 2018-05-23 Hosho Katsura , Tohru Koma

Development of next-generation electronic devices for applications call for the discovery of quantum materials hosting novel electronic, magnetic, and topological properties. Traditional electronic structure methods require expensive…

Computational Physics · Physics 2020-05-28 Hexin Bai , Peng Chu , Jeng-Yuan Tsai , Nathan Wilson , Xiaofeng Qian , Qimin Yan , Haibin Ling

A number of many-body problems can be formulated using Hamiltonians that are quadratic in the creation and annihilation operators. Here, we show how such quadratic Hamiltonians can be efficiently estimated indirectly, employing very few…

Quantum Physics · Physics 2011-01-17 Daniel Burgarth , Koji Maruyama , Franco Nori

An exact invariant is derived for three-dimensional Hamiltonian systems of $N$ particles confined within a general velocity-independent potential. The invariant is found to contain a time-dependent function $f_{2}(t)$, embodying a solution…

Classical Physics · Physics 2023-08-08 Jürgen Struckmeier , Claus Riedel

Many advancements have been made in the field of topological mechanics. The majority of the works, however, concerns the topological invariant in a linear theory. We, in this work, present a generic prescription of defining topological…

An electron moving in a magnetically ordered background feels an effective magnetic field that can be both stronger and more rapidly varying than typical externally applied fields. One consequence is that insulating magnetic materials in…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 Joel E. Moore , Ying Ran , Xiao-Gang Wen

Hamiltonian flows on compact surfaces are characterized, and the topological invariants of such flows with finitely many singular points are constructed from the viewpoints of integrable systems, fluid mechanics, and dynamical systems.…

Dynamical Systems · Mathematics 2022-06-24 Tomoo Yokoyama

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

We develop a topological classification of non-Hermitian effective Hamiltonians that depend on momentum and frequency. Such effective Hamiltonians are in one-to-one correspondence to single-particle Green's functions of systems that satisfy…

Strongly Correlated Electrons · Physics 2023-04-14 Maximilian Kotz , Carsten Timm

Topological insulators (TIs) are expected to be a promising platform for novel quantum phenomena, whose experimental realizations require sophisticated devices. In this Technical Review, we discuss four topics of particular interest for TI…

Mesoscale and Nanoscale Physics · Physics 2022-04-07 Oliver Breunig , Yoichi Ando

In the paper we construct an hierarchy of integrable Hamiltonian systems which describe the variation of n-wave envelopes in nonlinear dielectric medium. The exact solutions for some special Hamiltonians are given in terms of elliptic…

Mathematical Physics · Physics 2012-12-05 Anatol Odzijewicz , Tomasz Goliński

Nanostructures, such a quantum dots or nanoparticles, made of three-dimensional topological insulators (3DTIs) have been recently attracting increasing interest, especially for their optical properties. In this paper we calculate the energy…

Mesoscale and Nanoscale Physics · Physics 2022-11-23 Michele Governale , Fabio Taddei

One of the most used approaches in simulating materials is the tight-binding approximation. When using this method in a material simulation, it is necessary to compute the eigenvalues and eigenvectors of the Hamiltonian describing the…

Numerical Analysis · Computer Science 2009-10-29 Matthias Petschow , Edoardo Di Napoli , Paolo Bientinesi

Electric fields, applied to insulators, cause transitions between valence and conduction bands, giving rise to current. Adjustments of the Hamiltonian can perfect the quality of the insulator, shutting down transitions whilst fully…

Materials Science · Physics 2025-01-28 Rafael Hipolito , Paul M. Goldbart

Topological invariants allow to characterize Hamiltonians, predicting the existence of topologically protected in-gap modes. Those invariants can be computed by tracing the evolution of the occupied wavefunctions under twisted boundary…

Mesoscale and Nanoscale Physics · Physics 2018-04-04 D. Carvalho , N. A. Garcia-Martinez , J. L. Lado , J. Fernandez-Rossier

The entanglement spectrum is a useful tool to study topological phases of matter, and contains valuable information about the ground state of the system. Here, we study its properties for free non-Hermitian systems for both point-gapped and…

Mesoscale and Nanoscale Physics · Physics 2026-02-03 Carlos Ortega-Taberner , Lukas Rødland , Maria Hermanns

We propose general topological order parameters for interacting insulators in terms of the Green's function at zero frequency. They provide an unified description of various interacting topological insulators including the quantum anomalous…

Strongly Correlated Electrons · Physics 2012-08-15 Zhong Wang , Shou-Cheng Zhang

Topological quantum state described by the global invariant has been extensively studied in theory and experiment. In this letter, we investigate the relationship between \emph{Zitterbewegung} and the topology of systems that reflect the…

Quantum Physics · Physics 2022-11-23 Xin Shen , Yan-Qing Zhu , Zhi Li