Synthetic Space Photonic Topological Insulators Utilizing Dynamically-Invariant Structure

Via Zoom

Abstract

Topological insulators generally rely on a lattice, either in real-space (appearing as a periodic arrangement
of sites) or in synthetic dimensions, in the form of a ladder of energy levels, cavity modes, or some other
sequence of modes. In real-space, proximity facilitates coupling between adjacent lattice sites hence
enabling transport, but topological insulators employing synthetic dimensions require a means of modecoupling, to facilitate transport in the synthetic dimensions. Such mode coupling is generally obtained
through modulation.
In my talk, I present a dynamically-invariant synthetic-space photonic topological insulators: a twodimensional evolution-invariant photonic structure exhibiting topological properties in synthetic
dimensions. This non-magnetic structure is static, lacking any kind of dynamic modulation, yet it displays
an effective magnetic field in synthetic space and characterized by Chern number of one. I will show the
evolution of topological edge states along the edge, and on the interface between two such structures with
opposite synthetic-space chirality, and demonstrate their robust unidirectional propagation in the presence
of defects. Such topological evolution-invariant structures can be realized both in photonics and cold
atoms, thereby providing a fundamentally new mechanism for topological insulators.