Unidirectional transport of light along an atomic waveguide

Optical isolators that permit transport of light in one direction and block it in the opposite are a subject of considerable interest. Motivated by a recent prediction to engineer the dispersion relation of a waveguide constructed from atomic components, the possibility to create directional transport in an open, collective quantum system can now be explored. In this talk I will review an idealized model for an atomic chain whose optical response is engineered to display directionality. I will discuss a scattering formulation where mode-to-mode transmissions are readily calculated to fully characterize the optical response. Once the conditions for directionality are established, I explore how to retrieve excitations efficiently from a directional chain. To finish, I will include the effect of imperfections that break the periodicity of the array and show that backscattering is suppressed even in the presence of strong noise for a directional chain.