{"title":"Edge Spectrum for Truncated \\(\\mathbb {Z}_2\\)-Insulators","authors":"Alexis Drouot, Jacob Shapiro, Xiaowen Zhu","doi":"10.1007/s11040-025-09520-4","DOIUrl":null,"url":null,"abstract":"<div><p>Fermionic time-reversal-invariant insulators in two dimension – class AII in the Kitaev table – come in two different topological phases. These are characterized by a <span>\\(\\mathbb {Z}_2\\)</span>-invariant: the Fu–Kane–Mele index. We prove that if two such insulators with different indices occupy regions containing arbitrarily large balls, then the spectrum of the resulting operator fills the bulk spectral gap. Our argument follows a proof by contradiction developed in [16] for quantum Hall systems. It boils down to showing that the <span>\\(\\mathbb {Z}_2\\)</span>-index can be computed only from bulk information in sufficiently large balls. This is achieved via a result of independent interest: a local trace formula for the <span>\\(\\mathbb {Z}_2\\)</span>-index.</p></div>","PeriodicalId":694,"journal":{"name":"Mathematical Physics, Analysis and Geometry","volume":"28 3","pages":""},"PeriodicalIF":1.1000,"publicationDate":"2025-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Mathematical Physics, Analysis and Geometry","FirstCategoryId":"100","ListUrlMain":"https://link.springer.com/article/10.1007/s11040-025-09520-4","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"MATHEMATICS, APPLIED","Score":null,"Total":0}
引用次数: 0
Abstract
Fermionic time-reversal-invariant insulators in two dimension – class AII in the Kitaev table – come in two different topological phases. These are characterized by a \(\mathbb {Z}_2\)-invariant: the Fu–Kane–Mele index. We prove that if two such insulators with different indices occupy regions containing arbitrarily large balls, then the spectrum of the resulting operator fills the bulk spectral gap. Our argument follows a proof by contradiction developed in [16] for quantum Hall systems. It boils down to showing that the \(\mathbb {Z}_2\)-index can be computed only from bulk information in sufficiently large balls. This is achieved via a result of independent interest: a local trace formula for the \(\mathbb {Z}_2\)-index.
期刊介绍:
MPAG is a peer-reviewed journal organized in sections. Each section is editorially independent and provides a high forum for research articles in the respective areas.
The entire editorial board commits itself to combine the requirements of an accurate and fast refereeing process.
The section on Probability and Statistical Physics focuses on probabilistic models and spatial stochastic processes arising in statistical physics. Examples include: interacting particle systems, non-equilibrium statistical mechanics, integrable probability, random graphs and percolation, critical phenomena and conformal theories. Applications of probability theory and statistical physics to other areas of mathematics, such as analysis (stochastic pde''s), random geometry, combinatorial aspects are also addressed.
The section on Quantum Theory publishes research papers on developments in geometry, probability and analysis that are relevant to quantum theory. Topics that are covered in this section include: classical and algebraic quantum field theories, deformation and geometric quantisation, index theory, Lie algebras and Hopf algebras, non-commutative geometry, spectral theory for quantum systems, disordered quantum systems (Anderson localization, quantum diffusion), many-body quantum physics with applications to condensed matter theory, partial differential equations emerging from quantum theory, quantum lattice systems, topological phases of matter, equilibrium and non-equilibrium quantum statistical mechanics, multiscale analysis, rigorous renormalisation group.