An international team of Russian and American scientists presented the world’s first experimental device of a quadrupole topological isolator for photonics. This work may be able to create a way to create reliable classical and quantum-optical devices with high order of topological protection, as well as topologically protected sources of classical and quantum light. The research is published in Nature Photonics magazine.
Topological insulators are a class of materials that have unusual properties: inside the material topological insulator is a dielectric, but thinnest layer on its surface conducts the current . This means that the electric current runs in one direction only without interruptions or losses.
Over the last decade, development of ideas of such devices for photonics has begun. In order to expand the class of electronic topological insulators, scientists have replaced electrons with photons, which are quantums of electromagnetic radiation.
In the new work, scientists of ITMO University in cooperation with scientific group of the University of Maryland managed to implement the world’s first higher-order quadrupole topological isolators in photonics. For this purpose, scientists used silicon photonics. According to scientists, the most logical continuation of ongoing research may be the implementation of higher-order topological states in the three-dimensional structure.
“Now we are working on the implementation of higher-order topological states in three-dimensional geometries, trying to create a topologically protected three-dimensional waveguide. Imagine that light will spread in this structure along complex, non-flat three-dimensional trajectories without any dispersion at bends and with effective protection against disorder. It would be a very bright physics,” says Maxim Gorlach, co-author of the project and member of the Faculty of Physics and Technology at ITMO University.