A charge-tunable quantum dot strongly coupled to a nanophotonic cavity

Quantum dots (QDs) integrated with photonic structures is a promising scalable platform for the development of quantum networks and distributed quantum computing. Probabilistic charging of the QDs with electron/hole spins by adding a doping layer suffers from low charging stability due to carrier tunneling. Sandwiching the QDs into a p-n junction, which allows deterministically changing the charging state of the QDs by changing the external gate voltage can resolve this problem. Many experiments that previously have been achieved in probabilistic charged QDs sample, like cavity assisted QDs spin manipulation, have been successfully demonstrated using those charge tunable p-n junction QDs sample. However, the strong coupling between QDs spin and a microcavity, which is the basis of many QDs-based quantum information processing protocols and quantum optics experiments, hasn't been accomplished yet. Here, we report for the first time the realization of strong coupling between charge tunable QDs spin and a micro cavity, and the demonstration of spin population transfer via optical pumping. The strong coupling combined with deterministic charging paves way for applications of QDs in quantum optics.