Untying links through anti-parity-time-symmetric coupling

H C Wu,L Jin,Z Song,X M Yang

doi:10.1103/physrevb.102.161101

Abstract

We reveal how the vector field links are untied under the influence of anti-parity-time-symmetric couplings in a dissipative sublattice-symmetric topological photonic crystal lattice. The topology of the quasi-one-dimensional two-band system is encoded in the geometric topology of the vector fields associated with the Bloch Hamiltonian. The linked vector fields reflect the topology of the nontrivial phase. The topological phase transition occurs concomitantly with the untying of the vector field link at the exceptional points. Counterintuitively, more dissipation constructively creates a nontrivial topology. The linking number predicts the number of topological photonic zero modes.

Highlights

The robust topological structures of monopole, skyrmion, and vortex have attracted much research interest in optics, quantum physics, and condensed matter physics
Zero-energy Fermi surfaces can form knotted or linked nodal lines [12,13,14,15,16,17,18]; alternatively, the fictitious magnetic field of a topological system with topological defects, associated with vortex or antivortex textures, reflects nontrivial topology [19,20]. In this Rapid Communication, a nontrivial topology is extracted from the spin polarization, which is associated with a two-band topological system and defines a vector field
We visualize the vortex links, present alterations of the vector field topology under the influence of anti-paritytime-symmetric couplings, and reveal the untying of vector field links associated with a topological phase transition at the exceptional point (EP) of the nonHermitian topological system

Summary

INTRODUCTION

The robust topological structures of monopole, skyrmion, and vortex have attracted much research interest in optics, quantum physics, and condensed matter physics. Zero-energy Fermi surfaces can form knotted or linked nodal lines [12,13,14,15,16,17,18]; alternatively, the fictitious magnetic field of a topological system with topological defects, associated with vortex or antivortex textures, reflects nontrivial topology [19,20]. In this Rapid Communication, a nontrivial topology is extracted from the spin polarization, which is associated with a two-band topological system and defines a vector field. We demonstrate that more dissipation constructively creates nontrivial topology

DISSIPATIVE PHOTONIC CRYSTAL LATTICE

LINKING TOPOLOGY

TOPOLOGICAL PHOTONIC ZERO MODES

CONCLUSIONS