钙钛矿单量子点双激子辐射特性的研究

纠缠光子对的制备是实现量子信息处理的重要基础。钙钛矿量子点具有稳定的发光强度和光谱特性、极短的激子寿命和长的光学相干时间、便于加工和集成化的优势，其双激子态的级联辐射是制备纠缠光子源的有效量子资源。针对如何有效地获取钙钛矿单量子点双激子辐射的信息、抑制双激子的俄歇复合和提高双激子的辐射强度及实现偏振纠缠的双光子辐射等关键问题，本项目通过银纳米线的表面等离激元效应增强钙钛矿单量子点的双激子辐射率，同时利用N型半导体纳米材料抑制双激子的俄歇复合，在低激发条件下将双激子的量子产率提高到95%以上；利用时间分辨的光子统计方法有效地提取双激子光子，定量地研究钙钛矿单量子点表面俘获和激子带电对双激子辐射的影响。结合理论模拟探索银纳米线对双激子辐射的增强机制及双激子与表面等离激元的耦合作用；测量低温激子与双激子态的精细能级结构劈裂的光谱信息，通过电场调控精细能级结构劈裂实现偏振纠缠的双光子辐射。

The preparation of entangled photon pairs is the basis for realizing various quantum information processing. Perovskite quantum dots have the advantages of stable photoluminescence and spectral characteristics, extremely short exciton lifetime and long optical coherence time, easy processing and integration. The cascade transitions of biexciton states are effective for preparing quantum entangled photon sources. In the proposal, we will study how to effectively obtain the information of biexciton emission of single perovskite quantum dots, suppress the Auger recombination of biexciton, increase the emission intensity of biexciton, and realize source of polarization-entangled photons. The surface plasmon effect of silver nanowires is used to enhance the biexciton emission of single perovskite quantum dots, and N-type ITO semiconductor nanomaterial is used to suppress the Auger recombination of biexciton at the same time. As a result, biexciton quantum yield is expected to increase more than 95% at low excitation conditions. A time-resolved photon statistical method is used to effectively extract biexciton photons to quantitatively investigate the effects of extra charges and surface states on the biexciton emission of single perovskite quantum dots. We will investigate the mechanism of biexciton emission enhancement as well as the coupling effect between excitons and surface plasmons, and measurement of the fine structure splitting of both exciton and biexciton states at low temperature. The polarization-entangled photon source is expected to be achieved by the electric field controlling the exciton fine structure splitting.