Light-Controlled bright and stable plexcitonic quantum emitters operating in both single-photon and entangled-photon-pair emission modes
The emerging field of quantum information offers significant opportunities in quantum key distribution, quantum simulation and computation, metrology, and imaging. However, these applications require the use of quantum emitters that can generate single photons and pairs of entangled photons on demand. Perovskite quantum dots (PQDs), which can produce a highly coherent single-photon emission, are very promising as quantum emitters with a high single-photon purity, indistinguishability, and brightness. A unique property of PQDs is that, in contrast to many other emitters, biexciton states can be effectively generated in PQD. Two-photon photoluminescence (PL) resulting from biexciton recombination is one of effective ways of generating entangled photon pairs. However, the use of the full potential of PQDs as quantum emitters is hindered by the limitations associated with the instability of the PL signal and the low biexciton PL quantum yield.  Nanoscale plasmon–exciton interaction can significantly stabilize and improve the PL properties of PQDs due to the appearance of hybrid plasmon–exciton (plexciton) states serving as quantum emitters, thus overcoming the aforementioned limitations of PQDs. The main goal of the present QESPEM project is to design highly efficient plexcitonic quantum emitters operating as on-demand sources of pure single indistinguishable photons and pairs of entangled photons. To achieve this goal, the following objectives will be fulfilled: (1) to design quantum emitters based on the PQDs and plasmon nanostructures with implemented synergistic combination of plasmon-induces effects; (2) to develop new approaches and methods to control different regimes of plasmon–exciton interaction in the designed structures; (3) to optimize the conditions of light–matter coupling to achieve the highest values of the generation efficiency, single-photon purity, and indistinguishability for the single-photon mode and entanglement fidelity for the photon-pair mode.