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The topological invariant of a topological insulator (or superconductor) is given by the number of symmetry-protected edge states present at the Fermi level. Despite this fact, established expressions for the topological invariant require…

Mesoscale and Nanoscale Physics · Physics 2013-01-11 I. C. Fulga , F. Hassler , A. R. Akhmerov

We apply ideas from $C^*$-algebra to the study of disordered topological insulators. We extract certain almost commuting matrices from the free Fermi Hamiltonian, describing band projected coordinate matrices. By considering topological…

Mesoscale and Nanoscale Physics · Physics 2012-01-18 M. B. Hastings , T. A. Loring

Starting from a minimal model for a 2D nodal loop semimetal, we study the effect of chiral mass gap terms. The resulting Dirac loop anomalous Hall insulator's Chern number is the phase winding number of the mass gap terms on the loop. We…

Mesoscale and Nanoscale Physics · Physics 2016-10-19 Linhu Li , Miguel A. N. Araújo

In 2D Chern insulators (2D CI), the topology of the bulk states is captured by a topological invariant, the Chern number. The scalar bulk-boundary correspondence (sBBC) relates the change in Chern number across an interface with the number…

The topological classifications of quadratic bosonic systems according to the symmetries of the dynamic matrices from the equations of motion of closed systems and the effective Hamiltonians from the Lindblad equations of open systems are…

Mesoscale and Nanoscale Physics · Physics 2022-03-03 Yan He , Chih-Chun Chien

We propose a Chern insulator in a two-dimensional electron system with Dresselhaus spin-orbit coupling, ferromagnetism, and spin-dependent effective mass. The analytically-obtained topological phase diagrams show the topological phase…

Mesoscale and Nanoscale Physics · Physics 2019-10-10 Rui-An Chang , Ching-Ray Chang

We show that wavefunctions in a two-dimensional (2D) electron system with spin-orbit coupling can be characterized by a topological quantity--the Chern integer due to the existence of the intrinsic Kramers degeneracy. The…

Condensed Matter · Physics 2009-10-28 D. N. Sheng , Z. Y. Weng

We identify a new class of topologically driven phase transitions when calculating the Hall conductance of two-band Chern insulators in the long-time limit after a global quench of the Hamiltonian. The Hall conductance is expressed as the…

Quantum Gases · Physics 2016-07-19 Pei Wang , Stefan Kehrein

We present an alternative approach to studying topology in open quantum systems, relying directly on Green's functions and avoiding the need to construct an effective non-Hermitian Hamiltonian. We define an energy-dependent Chern number…

Mesoscale and Nanoscale Physics · Physics 2021-02-17 M. Belén Farias , Solofo Groenendijk , Thomas L. Schmidt

Second-order topological insulators are crystalline insulators with a gapped bulk and gapped crystalline boundaries, but topologically protected gapless states at the intersection of two boundaries. Without further spatial symmetries, five…

Mesoscale and Nanoscale Physics · Physics 2017-12-20 Josias Langbehn , Yang Peng , Luka Trifunovic , Felix von Oppen , Piet W. Brouwer

Quench dynamics of topological phases have been studied in the past few years and dynamical topological invariants are formulated in different ways. Yet most of these invariants are limited to minimal systems in which Hamiltonians are…

Mesoscale and Nanoscale Physics · Physics 2026-05-04 Xi Wu , Ze Yang , Fuxiang Li

A family of semiconductors called as Chern band insulator are shown to host exciton bands with non-zero topological Chern integers and chiral exciton edge modes. Using a prototypical two-band Chern insulator model, we calculate a…

Mesoscale and Nanoscale Physics · Physics 2017-10-11 Ke Chen , Ryuichi Shindou

One of the main topological invariants that characterizes several topologically-ordered phases is the many-body Chern number (MBCN). Paradigmatic examples include several fractional quantum Hall phases, which are expected to be realized in…

We consider the two-dimensional topological Chern insulator in the presence of static disorder. Generic quantum states in this system are Anderson localized. However, topology requires the presence of a subset of critical states, with…

Mesoscale and Nanoscale Physics · Physics 2023-08-29 Mateo Moreno-Gonzalez , Johannes Dieplinger , Alexander Altland

Dual topological insulators (DTIs) are simultaneously protected by time-reversal and crystal symmetries, representing advantageous alternatives to conventional topological insulators. By combining ab initio calculations and the…

Mesoscale and Nanoscale Physics · Physics 2025-02-24 Warlley H. Campos , Poliana H. Penteado , Julian Zanon , Paulo E. Faria Junior , Denis R. Candido , J. Carlos Egues

Topology has appeared in different physical contexts. The most prominent application is topologically protected edge transport in condensed matter physics. The Chern number, the topological invariant of gapped Bloch Hamiltonians, is an…

Mesoscale and Nanoscale Physics · Physics 2018-01-24 Thomas Fösel , Vittorio Peano , Florian Marquardt

The discovery that the band structure of electronic insulators may be topologically non-trivial has unveiled distinct phases of electronic matter with novel properties. Recently, mechanical lattices have been found to have similarly rich…

Mesoscale and Nanoscale Physics · Physics 2018-10-10 Noah P. Mitchell , Lisa M. Nash , Daniel Hexner , Ari Turner , William T. M. Irvine

It is shown analytically that the energy-conserving implicit nonsymplectic scheme of Bacchini, Ripperda, Chen and Sironi provides a first-order accuracy to numerical solutions of a six-dimensional conservative Hamiltonian system. Because of…

General Relativity and Quantum Cosmology · Physics 2021-12-08 Shiyang Hu , Xin Wu , Enwei Liang

To define the topology of driven systems, recent works have proposed synthetic dimensions as a way to uncover the underlying parameter space of topological invariants. Using time as a synthetic dimension, together with a momentum dimension,…

Materials Science · Physics 2022-11-09 I-Te Lu , Dongbin Shin , Umberto De Giovannini , Hannes Hübener , Jin Zhang , Simone Latini , Angel Rubio

The quantum anomalous Hall (QAH) state is a two-dimensional topological insulating state that has quantized Hall resistance of h/Ce2 and vanishing longitudinal resistance under zero magnetic field, where C is called the Chern number. The…

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