Single-photon nonlinear optics with a semiconductor quantum dot

Self-assembled quantum dots are artificial atoms with large optical oscillator strength. When coupled with nanophotonic cavities and waveguides, they routinely attain the strong coupling or the large cooperativity regime, where the quantum dots can interact with photons in the cavity or the waveguide near-deterministically. Such a strong light-matter interface allows giant optical nonlinearity at the single-photon level. In this chapter, we review the theoretical and experimental progress in single-photon nonlinear optics induced by single semiconductor quantum dots. We highlight their applications in nonclassical light generation, spin-photon quantum switches, and single-photon optical transistors. These results show that semiconductor nanophotonic devices can produce strong and controlled photon-photon interactions that could enable high-bandwidth photonic quantum information processing.