Photon-pair production at the nanoscale with hybrid nonlinear/plasmonic antennas

Reducing a nonlinear photon pair source to the nanoscale entails drastic reduction in efficiency and thus requires better tools for its evaluation and optimization. In this context, we develop a formalism for the investigation of spontaneous parametric downconversion in hybrid plasmonic structures that combine plasmonic resonances and intrinsic nonlinearity of a nonlinear medium. Combining quantum and numerical approaches, we quantitatively evaluate photon pair correlation for a realistic experimental configuration. We thereby show that hybrid structures embedding a nanocrystal and plasmonic antennas allow for a 105-fold increase in pair production rate in com-parison with a single nanocrystal, thus displaying an efficiency close to the best nanoscale sources to date. & COPY; 2023 Optica Publishing Group