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

Integration of photon pairs nanosources is a major challenge for quantum technology. In this context, we develop a formalism for the investigation of Spontaneous Parametric Down Conversion in hybrid structures that combine plasmonic resonances and intrinsic nonlinearity. Using quantum and numerical approaches together, we quantitatively evaluate photon pair correlation measurements for realistic experimental configurations. Hybrid structures embedding a small nanocystal allow for a $10^{3}$ fold increase in pair production compared to the same nanocrystal alone and a photon pair production efficiency close to the best source to date.