Topological insulators have been an exciting field of research with fundamental interest as well as practical applications such as robust transport of electrons and light, and topological quantum computing. The hallmark of such conventional topological insulators is the presence of conducting boundary modes which have one dimension lower than the insulating bulk system that hosts them—for example a one-dimensional edge mode at the boundary of a two-dimensional system, or a two-dimensional surface state at the boundary of a three-dimensional system. In 2017, scientists generalized this concept to predict a new phase of matter called higher-order topological insulators (HOTIs), which support ‘corner modes’—e.g. a zero-dimensional mode in a two-dimensional system. Since then, there have been several experimental demonstrations of this new HOTI phase, most of which involve complicated geometries. Moreover, these previous systems are fixed—i.e. one cannot dynamically switch or tune their higher-order topological behavior once they are fabricated.
Click here for original story, Synthetic dimensions enable a new way to construct higher-order topological insulators
Source: Phys.org