Synchronized in-gap edge states and robust copropagation in topological insulators without magnetic flux

Abstract

Copropagation of antichiral edge states in the metallic phase requires the bulk states as counterpropagating modes. Without the band gap protection, the copropagation along the boundaries is easily scattered into the bulk and the counterpropagation in the bulk is not robust against disorder and defects. Here, we propose a novel time-reversal symmetric topological insulator holding the synchronized in-gap edge states. To prevent the participation of bulk states, we introduce the time-reversal symmetry to detach the edge states from the bulk band, then the robust copropagation is realized through widening the band gap across a metal-insulator transition with anisotropic next-nearest-neighbor couplings. The time-reversal symmetry ensures the in-gap edge states with opposite momenta as the counterpropagating modes. The inversion symmetry protects the quantized polarization as a topological invariant. The synchronized in-gap edge states not only enrich the family of topological edge states, but also provide additional flexibility in the design of reconfigurable topological optical devices. Our findings open a new avenue for the tailored robust wave transport using the in-gap edge states for future acousto-optic topological metamaterials.

19 pages, 5 figures

References in corpus (36)

• Topological Photonics
• Photonic Floquet Topological Insulators
• Possible Realization of Directional Optical Waveguides in Photonic Crystals with Broken Time-Reversal Symmetry
• Quantized Electric Multipole Insulators
• Photonic Analogue of Two-dimensional Topological Insulators and Helical One-Way Edge Transport in Bi-Anisotropic Metamaterials
• Robust optical delay lines via topological protection
• Acoustic topological insulator and robust one-way sound transport
• Observation of topological valley transport of sound in sonic crystals
• Quantization of fractional corner charge in $C_n$-symmetric higher-order topological crystalline insulators
• Topological Anderson Insulator
• Topologically-protected refraction of robust kink states in valley photonic crystals
• Visualization of unidirectional optical waveguide using topological photonic crystals made of dielectric material
• Hybrid higher-order skin-topological modes in non-reciprocal systems
• Observation of second-order topological insulators in sonic crystals
• Topologically protected acoustic helical edge states and interface states in strongly coupled metamaterial ring lattices
• Synthetic gauge fields and Weyl point in Time-Reversal Invariant Acoustic Systems
• Realization of a three-dimensional photonic topological insulator
• Nonlinear control of PT-symmetry and non-Hermitian topological states
• Valley Topological Phases in Bilayer Sonic Crystals
• Experimental Observation of Higher-Order Topological Anderson Insulators
• Helical Topological Edge States in a Quadrupole Phase
• Measurement of topological invariants in a 2D photonic system
• Antichiral edge states in a modified Haldane nanoribbon
• Topologically protected valley-dependent quantum photonic circuits
• Observation of photonic antichiral edge states
• Reconfigurable topological phases in next-nearest-neighbor coupled resonator lattices
• Quantum time reflection and refraction of ultracold atoms
• Antihelical Edge States in Two-dimensional Photonic Topological Metals
• Discovering topological surface states of Dirac points
• Realization of Surface-Obstructed Topological Insulators
• Optically reconfigurable quantum spin-valley Hall effect of light in coupled nonlinear ring resonator lattice
• Edge State, Band Topology, and Time Boundary Effect in the Fine-Grained Categorization of Chern Insulators
• Anti-chiral edge states and hinge states based on the Haldane model
• Antichiral states in twisted graphene multilayers
• Realization of time-reversal invariant photonic topological Anderson insulators
• Observation of period-doubling Bloch oscillations