  We show that the two-photon transition rates of quantum dots coupled to
nanocavities are enhanced by up to 8 orders of magnitude relative to quantum
dots in bulk host. We then propose how to take advantage of this enhancement to
implement coherent quantum dot excitation by two-photon absorption, entangled
photon pair generation by two-photon spontaneous emission, and single-photon
generation at telecommunication wavelengths by two-photon stimulated and
spontaneous emission.
