Quantum dots interfaced with alkali atoms: Filtering, delaying and quantum interfering single photons

Hybrid quantum systems are based on the capability to interface elements from complementary fields: only the best properties from all components are utilized, overcoming the limitation of each field. Semiconductor quantum dots (QDs) are well established as sources of bright, pure and highly indistinguishable on-demand single photons. A crucial limitation is given by the relatively short coherence time. This can be overtaken by interfacing them to alkali atoms, which display a very long coherence time and will benefit from the superior properties of QD-based non-classical light sources [1].