Quantum Optics Seminar by Mark S. Rudner

Patterning media for chiral (topological) wave propagation

Abstract: The propagation of waves in media with wavelength-scale structure can be drastically different from that of free waves.  As a well-known example, the dispersion relation characterizing wave propagation through a periodic medium (like an electron in a crystal, or electromagnetic radiation in a photonic crystal) is organized into bands, with specific forbidden frequency ranges where waves cannot propagate.  In recent years, we have come to appreciate that the structure of the eigenmode wave functions in such Bloch bands may also lead to novel dynamic phenomena, such as the "anomalous velocity" or chiral propagation along edges, in the presence of inhomogeneities or sample boundaries.  In this talk I will review the basics of band topology, and will discuss recent progress in our efforts to learn how to dynamically control the topological characteristics of electronic or cold atomic systems.  These ideas can also be applied to optical systems, yielding new routes obtaining topologically-protected (chiral) propagation of light.