This cluster of papers focuses on the physics and applications of quantum dot devices, semiconductor materials, and single-photon sources. It covers topics such as band parameters for III–V compound semiconductors, strong coupling in quantum dot–semiconductor microcavity systems, and the generation of entangled photons from single quantum dots. The research also delves into the electronic structure of quantum dots, electrically driven single-photon sources, and the development of near-optimal single-photon sources in the solid state.