2021/12/31 by Takumi Bessho, Ken Mochizuki, Hideaki Obuse +1
Computer Science · Materials Science · Mathematics · Physics and Astronomy · #Boundary (topology) #Floquet theory #Graphene research and applications #Mathematics #Physics #Quantum #Quantum Computing Algorithms and Architecture #Quantum and electron transport phenomena #Quantum computer #Quantum mechanics #Quantum walk #Symmetry protected topological order #Topological degeneracy #Topological entropy in physics #Topological insulator #Topological order #Topological quantum number #Topology (electrical circuits) #cond-mat.mes-hall #math-ph #math.MP #quant-ph
paper · pdf · doi:10.1103/physrevb.105.094306
published as Phys. Rev. B 105, 094306 (2022) · 22 pages, 15 figures, 6 tables
openalex publication_date 2022/03/14 · arxiv created 2022/03/16 · arxiv updated 2022/03/17 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
Bulk-boundary correspondence is a fundamental principle for topological phases where bulk topology determines gapless boundary states. On the other hand, it has been known that corner or hinge modes in higher order topological insulators may appear due to "extrinsic" topology of the boundaries even when the bulk topological numbers are trivial. In this paper, we find that Floquet anomalous boundary states in quantum walks have similar extrinsic topological natures. In contrast to higher order topological insulators, the extrinsic topology in quantum walks is manifest even for first-order topological phases. We present the topological table for extrinsic topology in quantum walks and illustrate extrinsic natures of Floquet anomalous boundary states in concrete examples.