Topologically invisible defects in chiral mirror lattices

Abstract

One of the hallmark of topological insulators is having conductivity properties that are unaffected by the possible presence of defects. In this work, we go beyond backscattering immunity and obtain topological invisibility across defects or disorder. Using a combination of chiral and mirror symmetry, the transmission coefficient is guaranteed to be unity. Importantly, but no phase shift is induced making the defect completely invisible. Many lattices possess the chiral-mirror symmetry, and we choose to demonstrate the principle on an hexagonal lattice model with Kekule distortion displaying topological edge waves, and we show analytically and numerically that the transmission across symmetry preserving defects is unity. We then realize this lattice in an acoustic system, and confirm the invisibility with numerical experiments. We foresee that the versatility of our model will trigger new experiments to observe topological invisibility in various wave systems, such as photonics, cold atoms or elastic waves.

9+6 pages, 6+5 figures. Few minor corrections and clarifications. Match published version

References in corpus (10)

• Scheme to Achieve Silicon Topological Photonics
• Observation of phononic helical edge states in a mechanical 'topological insulator'
• Observation of topological valley transport of sound in sonic crystals
• Topological Defects and Gapless Modes in Insulators and Superconductors
• Novel Topological Phase with Zero Berry Curvature
• Edge waves in plates with resonators: An elastic analogue of the quantum valley Hall effect
• Pseudospins and topological effects of phonons in a Kekule lattice
• Topological zero modes and Dirac points protected by spatial symmetry and chiral symmetry
• Topological two-dimensional Su-Schrieffer-Heeger analogue acoustic networks: Total reflection at corners and corner induced modes
• Topological Modes Protected by Chiral and Two-Fold Rotational Symmetry in a Spring-Mass Model with a Lieb Lattice Structure

Cited by in corpus (3)

• Symmetry-protected Landau-Zener-Stückelberg-Majorana interference and non-adiabatic topological transport of edge states
• Canonical scattering problem in topological metamaterials: Valley-Hall modes through a bend
• Single $\pi$-flux hosting topological defect modes in bilayer acoustic metamaterials