Tailoring Wavelength- and Emitter-Orientation-Dependent Propagation of Single Photons in Silicon Nanowires

Quantum nano-optics aims at transposing the concepts of quantum optics at the nanoscale. In this context, nitrogen-vacancy color centers in nanodiamonds are particularly interesting model sources as they emit single photons one by one with a broad spectral distribution between 600 and 800 nm. We deposit such quantum emitters at the extremities of silicon nanowires and analyze the effects of this interaction via spectrally resolved confocal microscopy. We demonstrate that the single-photon emission can be guided over several microns under conservation of their quantum statistics, while the silicon nanowires act as spectral filters for the quantum emission. Numerical simulations are in very good agreement with experiments, and indicate that the modal landscape of these nanowaveguides and the according coupling efficiencies with quantum emitters can be designed such that only light from emitters of specific orientations is efficiently guided through the nanowire, enabling a unique quantum state selectivity at a micrometer length scale. Our work opens the door to a genuine modal control of single-photon transfer in subwavelength waveguides, paving the way to future fundamental studies and toward integrated and multiwavelength photonics applications in quantum nano-optics.