Final Report Summary - PICSEN (Propagative and Internal Coherence in Semiconductor Nanostructures)
In the ERC StG “PICSEN”, I proposed to embed solid state single emitters (realized by semiconductor quantum dots) within suitably designed nanophotonic devices, to improve the retrieval of their coherent nonlinear responses, in particular of their four-wave mixing signals. This turned out to be a ground-breaking idea and its execution over the last years has redefined the state-of-the-art in the field, as confirmed by the publication outcome of this project. I demonstrated the generality of this winning strategy using various devices: suspended photonic waveguide antennas, photonic defects, microlenses, planar and pillar microcavities and solid immersion lenses. In each of these cases, the remedy brought by nanophotonics was to locally amplify the field around the quantum dot dipole, permitting to drastically decrease the resonant background, and in parallel to improve the four-wave mixing collection efficiency: more signal with less background, in the simplest words. As a result, the sensitivity of the single-exciton coherence retrieval is has been enhanced by up to four orders of magnitude with respect to a quantum dot in bulk media, rendering single-exciton FWM to be a routine observable in my lab these days. This concept now radiates towards the community and stimulates the progress within the field.