In novel materials known as photonic topological insulators, wavelengths of light can flow around sharp corners with virtually no losses. Now scientists have witnessed key details of what the light does inside these structures, which could help them to better engineer these materials for real-world applications.
Topology is the branch of mathematics that explores what features of shapes withstand deformation. For instance, an object shaped like a doughnut can get pushed and pulled into the shape of a mug, with the doughnut’s hole forming the hole in the cup’s handle, but it could not get deformed into a shape that lacked a hole.
Using insights from topology, researchers developed the first electronic topological insulators in 2007. Electrons traveling along the edges or surfaces of these materials strongly resist any disturbances that might hinder their flow, much as a doughnut might resist any change that would remove its hole.