Advances in Metaphotonics Empowered Single Photon Emission

Spontaneous photon emission can be drastically modified by placing quantum emitters (QEs) in nanostructured environment, resulting in dramatically enhanced emission rates due to the Purcell effect along with generation of collimated single-photon beams propagating in design directions and featuring well-defined polarization states. Recent advances in single-photon generation engineering demonstrate fascinating possibilities for the directional emission of photons with designed spin and orbital angular momenta, a development that is crucial for exploiting the full potential of QEs within quantum information technologies. Although many different nanostructured configurations are considered for hosting QEs to mold single-photon beams, collimating of the latter requires relatively large interaction areas to be involved, thus making the use of metasurfaces preferential. Furthermore, optical metasurfaces consisting of planar arrays of resonant nanoscale elements offer complete control over optical fields and thereby design freedom in shaping single-photon emission. Here, recent advances in exploiting quantum optical metasurfaces for achieving enhanced and directional emission of single photons with specified polarization properties are overviewed. Special attention is paid to hybrid plasmon–QE coupled metasurfaces based on efficient QE coupling to surface plasmon modes that are subsequently outcoupled by designed dielectric nanoarrays into free propagating photon emission. Perspectives for future developments of metasurface empowered QEs are also discussed.