Biexcitons are a manifestation of many-body excitonic interactions, which are crucial for quantum information and computation in the construction of coherent combinations of quantum states. However, due to their small binding energy and low transition efficiency, most biexcitons in conventional semiconductors exist either at cryogenic temperatures or under femto-second pulse laser excitation. In this talk, we demonstrated strong biexciton emissions from CsPbBr₃ nanoplatelets with continuous-wave excitation at room temperature by coupling them with a plasmonic nanogap. The exciton occupancy required to generate biexciton was reduced ~10⁶ times in the Ag nanowire- Ag film nanogaps. The extremely large enhancement of biexciton emissions was driven by nonlinear Fano resonance between biexciton and surface plasmon cavity modes. These results provide new pathways to develop high efficiency non-blinking single photon sources of biexciton, entangled light sources, and lasers based on biexciton states.
 

Xinfeng Liu received his Ph.D. from National Center of Nanoscience and Technology, Chinese Academy of Sciences in 2011. In 2011-2015, he worked as a postdoctoral fellow in Nanyang Technological University (NTU), Singapore. In 2015, he joined the National Center of Nanoscience and Technology (NCNST) and worked as the distinguished professor and project leader. His research group mainly focuses on light–matter interaction and ultrafast spectroscopy at micro and nanometer scale.
 

This work is supported by Ministry of Science and Technology, National Natural Science Foundation of China and Beijing Municipal Natural Science Foundation.