Spiral dislocation gives 3D topological photonics a robust edge

https://phys.org/news/2022-09-spiral-dislocation-3d-topological-photonics.html

"combines the concept of synthetic dimensions with a specific type of defect—a so-called screw dislocation. This judiciously placed defect continuously connects the individual planes of the lattice by twisting them around a central axis similar to a corkscrew. Co-author and Ph.D. student Julius Beck explains that "like transforming a loose stack of rings into a seamlessly connected spiral, this intentional defect allowed us to create the first 3D topological insulator for light"