The route to quantum light via semiconductor excitons

Manipulating light down to the level of single photons is an important goal of quantum optics. Semiconductor excitons afford a convenient integrable platform for this purpose. However, the optical nonlinearities of such systems are typically too weak to induce significant quantum correlations. Here, we present new strategies for this purpose that are effective in the presence of strong dissipation. These possibilities are opened up by high-lying excitonic Rydberg states with unusually strong interactions. We discuss recent progress with Rydberg excitons in bulk and two-dimensional systems along with their specific challenges, which we show can be overcome with new theoretical proposals. The results promise record photon correlations and, ultimately, provide a positive outlook on quantum optics with semiconductor excitons.