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Two-dimensional 2-bands insulators breaking time reversal symmetry can present topological phases indexed by a topological invariant called the Chern number. Here we first propose an efficient procedure to determine this topological index.…

Mesoscale and Nanoscale Physics · Physics 2012-05-28 Doru Sticlet , Frederic Piéchon , Jean-Noël Fuchs , Pavel Kalugin , Pascal Simon

In this paper, we present a novel experimental approach for simulating and detecting topological invariants using ultracold fermions confined in two-dimensional hexagonal optical lattices. We propose achieving two-fold degenerate four-band…

Quantum Gases · Physics 2024-07-12 Jing-Xin Liu , Jian-Te Wang , Hai-Tao Ding

Topological phases with broken time-reversal symmetry and Chern number |C|>=2 are of fundamental interest, but it remains unclear how to engineer the desired topological Hamiltonian within the paradigm of spin-orbit-coupled particles…

Quantum Gases · Physics 2021-06-09 Abhijeet Alase , David L. Feder

We present measurements of a topological property, the Chern number ($C_\mathrm{1}$), of a closed manifold in the space of two-level system Hamiltonians, where the two-level system is formed from a superconducting qubit. We manipulate the…

We propose an alternative formulation of the $Z_2$ topological index for quantum spin Hall systems and band insulators when time reversal invariance is not broken. The index is expressed in terms of the Chern numbers of the bands of the…

Mesoscale and Nanoscale Physics · Physics 2009-11-01 Rahul Roy

Topological invariants, such as the Chern number, characterise topological phases of matter. Here we provide a method to detect Chern numbers in systems with two distinct species of fermion, such as spins, orbitals or several atomic states.…

In this work, we propose a new and simple model that supports Chern semimetals. These new gapless topological phases share several properties with the Chern insulators like a well-defined Chern number associated to each band, topologically…

Mesoscale and Nanoscale Physics · Physics 2015-12-09 Giandomenico Palumbo , Konstantinos Meichanetzidis

We demonstrate the realization of topological band structures by exploiting the intrinsic spin-orbit coupling of dipolar interactions in combination with broken time-reversal symmetry. The system is based on polar molecules trapped in a…

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

High spin Chern-number insulators (HSCI) have emerged as a novel 2D topological phase of condensed matter that is beyond the classification of topological quantum chemistry. In this work, we report the observation of a semimetallic Sb…

Topologically protected surface modes of classical waves hold the promise to enable a variety of applications ranging from robust transport of energy to reliable information processing networks. The integer quantum Hall effect has delivered…

Mesoscale and Nanoscale Physics · Physics 2020-08-25 Weiyin Deng , Xueqin Huang , Jiuyang Lu , Valerio Peri , Feng Li , Sebastian D. Huber , Zhengyou Liu

Quantum systems are often described by parameter-dependent Hamiltonians. Points in parameter space where two levels are degenerate can carry a topological charge. Here we theoretically study an interacting two-spin system where the…

Mesoscale and Nanoscale Physics · Physics 2022-02-03 György Frank , Dániel Varjas , Péter Vrana , Gergő Pintér , András Pályi

We propose an approach to induce nontrivial bands with non-zero Chern numbers by utilizing strong spin-orbit coupling in transition metal dichalcogenides with dopants. We demonstrate that a doped state near the valence-band edge induces…

Mesoscale and Nanoscale Physics · Physics 2026-03-24 Dinh Loc Duong

Chern numbers are gaining traction as they characterize topological phases in various physical systems. However, the resilience of the system topology to external perturbations makes it challenging to experimentally investigate transitions…

Quantum Physics · Physics 2022-11-28 Junghyun Lee , Keigo Arai , Huiliang Zhang , Mark J. H. Ku , Ronald L. Walsworth

We present an approach for the calculation of the $\mathbb{Z}_2$ topological invariant in non-crystalline two-dimensional quantum spin Hall insulators. While topological invariants were originally mathematically introduced for crystalline…

Mesoscale and Nanoscale Physics · Physics 2023-02-28 Roberta Favata , Antimo Marrazzo

We investigate how topological Chern numbers can be defined when single-particle states hybridize with continua. We do so exemplarily in a bosonic Haldane model at zero temperature with an additional on-site decay of one boson into two and…

Mesoscale and Nanoscale Physics · Physics 2025-07-16 B. Hawashin , J. Sirker , G. S. Uhrig

This work explores the topological properties of altermagnets, a novel class of collinear magnetic materials. We employ equivariant K-theory of magnetic groups and Hamiltonian models to formulate a robust $C^z_4 \mathbb{T}$ topological…

Materials Science · Physics 2025-03-03 Rafael Gonzalez-Hernandez , Higinio Serrano , Bernardo Uribe

We argue that ferromagnetic transition metal nanoparticles with fewer than approximately 100 atoms can be described by an effective Hamiltonian with a single giant spin degree of freedom. The total spin $S$ of the effective Hamiltonian is…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 C. M. Canali , A. Cehovin , A. H. MacDonald

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 analyze a measurement scheme that allows determination of the Berry curvature and the topological Chern number of a Hamiltonian with parameters exploring a two-dimensional closed manifold. Our method uses continuous monitoring of the…

Quantum Physics · Physics 2017-07-12 Peng Xu , Alexander Holm Kiilerich , Ralf Blattmann , Yang Yu , Shi-Liang Zhu , Klaus Mølmer
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