Untying links through anti-parity-time-symmetric coupling

TL;DR

This paper demonstrates how anti-parity-time-symmetric couplings in a dissipative photonic lattice can untie vector field links, revealing topological phase transitions and the role of dissipation in creating nontrivial topology.

Contribution

It introduces a novel mechanism where anti-PT-symmetric couplings untie vector links, linking topology, dissipation, and exceptional points in photonic systems.

Findings

Linked vector fields encode topological phases.

Topological phase transition coincides with untying at exceptional points.

Dissipation can induce nontrivial topology.

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.