Nonlinear quantum photonics: from passive to active devices

Nir Rotenberg
University of Copenhagen

Abstract

Quantum photonics is no longer just an exploration of fundamental physical laws; we now also use quantum effects to construct devices to, for example, produce single photon sources or perform quantum measurement. That is, we are in the process of bringing the research from the lab and into the marketplace. This process, however, is in its infancy, and the type and power of the resultant devices still strongly depends on the way in which we can generate and manipulate quantum states.

In this talk, I focus on some of our recent results in observing and controlling nonlinear light-matter interactions using solid-state emitters coupled to nanophotonic waveguides. I begin by explaining the passive nonlinearities of these emitter-waveguide systems, and how these can form the basis for a photon sorter: a device that can enable a deterministic Bell-state measurement, and thus forms a key component of a long-range quantum network. I then turn to our recent efforts to actively control these quantum nonlinear interactions, and bring multicolor nonlinear optics to the single-photon level, thereby opening routes towards active quantum devices such as photon switches, routers, or even reconfigurable networks.