Experimental demonstration of photonic Floquet topological insulators

A topological insulator is a completely new phase of matter with an insulating interior and conduction only at the edges [1]. Perhaps its most impressing feature is that the conducting electron states at the edges do not experience scattering in case of defects or disorder due to the Kramers degeneracy, which disallows coupling to the counterpopagating state. This provides a robustness which is otherwise only known from superconductors. The fact that topological insulators exist at room temperature and without an external magnetic field means that they are promising candidates for a variety of applications as in spintronics and exotic new phases therein may have application for robust quantum computing.