Spin-Polarized Photon Emission by Resonant Multipolar Nanoantennas

We demonstrate nanoscale spin control of photons emitted by an atomic system coupled to a compact plasmonic nanoantenna supporting phase-locked interference of different multipolar moments within a single resonance. Experimentally we observe chiral light emission from quantum dots over split-ring resonant nanoantennas, where the spin of the emitted photons is locked to their transverse momentum. We demonstrate that the polarization can vary from linear to elliptical with ellipticity reaching +/- 0.5 for emission into opposite halves of the symmetry plane of the nanoantenna.