Theory of tunable embedded quantum dots in solid-state matrices

Multiple embedded quantum dot system is a highly tunable hybrid platform with a variety of phenomena. Experiments have shown a slight amount of embedded quantum dots leads to superior performance in conductivity, thermoelectricity, and optical properties, far beyond what is achievable through chemical doping. However, the fundamental theory of embedded quantum dots is missing, which constrains material design efforts to trial-and-error approaches. In this work, we provide a theoretical foundation that predicts electrical and optical properties, such as conductivity and photoluminescence spectra, in embedded quantum dots, and propose methods to tune these properties in a large range with external light and magnetic fields. Our theory is based on Green's function calculation and discusses multiple competing terms that co-exist in the system, including the energy spacing of multi-level quantum dots, the randomness of embedded quantum dots' positions, the on-site Coulomb interaction which leads to Kondo effects, and the Hund's coupling. We show novel phenomena, such as Anderson localization, Coulomb blockade, and singlet-triplet transition of quantum dot inner states, can appear and be controlled by external fields.