Multipolar radiation of quantum emitters with nanowire optical antennas

Multipolar transitions other than electric dipoles are generally too weak to be observed at optical frequencies in single quantum emitters. For example, fluorescent molecules and quantum dots have dimensions much smaller than the wavelength of light and therefore emit predominantly as electric dipoles. Here we demonstrate controlled emission of a quantum dot into multipolar radiation through selective coupling to a linear nanowire antenna. The antenna resonance tailors the interaction of the quantum dot with light, effectively creating a hybrid nanoscale source beyond the simple Hertz dipole. Our findings establish a basis for the controlled driving of fundamental modes in nanoantennas and metamaterials, for the understanding of the coupling of quantum emitters to nanophotonic devices such as waveguides and nanolasers, and for the development of innovative quantum nano-optics components with properties not found in nature. Nanoantennas provide improvements in detection and fluorescence of nanoscale objects, which are usually limited to electric dipole radiation. By exploiting coupling to nanowire antennas, Curto et al . show controlled multipolar emission of a quantum dot, offering a novel multipolar photon source.