Light Emission Of Quantum Dot-metal Nanoparticles Coupling System

For the developments of quantum computing,quantum encryption and scalable optical quantum information processing,the integrated solid-state single photon source with high purity,high efficiency is required,the emitted photons should be indistinguishable and,deterministic.In the process of research and development,quantum dot-microcavities coupling system has become a research hotspot in the past two decades because of its high controllability,integration and huge development potential.The system has several requirements for the performance of microcavity,including the small effective mode volume.Due to the extremely small mode volume which can break through the optical diffraction limit,the localized surface plasmons generated on the surface of metal nanoparticles have attracted extensive attention in recent research.This paper focuses on the interaction and sub-Poissonian photon statistics in the coupled quantum dot-metal nanoparticles system,the main work and innovations are as follows:1.Strong interaction in quantum dot-metal nanocones coupling system.The plasmons on the surface of metal nanoparticles are equivalent to a single-mode cavity,and the quantum dot is placed in the center of a pair of spatially symmetric metal nanocones,so the coupling system is regarded as a Jaynes-Cummings model.By adjusting the sharpness of the cone,it is found that the sharper structure can further improve the electric field strength between the two tips,and the corresponding spectral linewidth is narrowed,which qualitatively indicates that the sharper metal nanostructure is more conducive to enhance the interaction with the quantum dot.By fitting the spectra calculated by the finite element method and the framework of cavity quantum electrodynamic system in order,the specific parameters of the coupling system can be obtained,such as the dot-cavity coupling strength g,cavity mode decay rate k,etc.By using these parameters,the quantitative analysis of the system is further carried out,and it is found that the structure with higher sharpness has a larger g/K ratio,so the above qualitative conclusion is verified.In addition,the phenomena of Rabi splitting and anti-crossing observed in the coupled system indicate that there is a strong interaction between the quantum dot and the metal nanoparticles.2.Optical properties of gain assisted quantum dot-metal semi ellipsoid dimer coupling system.In order to further enhance the coupling strength between quantum dot and cavity,a layer of gain media is placed on the surface of quantum dot and metal nanoparticles.The results show that the dynamic compensation between the gain media and the metal material can effectively improve the quality factor of the localized surface plasmons mode,and make the light field more concentrated in the center of the dimer,that is,the region of the quantum dot.Choosing the appropriate gain coefficient,the quality factor of the cavity mode can be increased up to 200 times,the hybrid system will stride from weak coupling(no gain)to strong coupling regime.At the same time,the photon in the cavity will change to sub-Poissonian statistics,and the zero delay second-order autocorrelation function will be reduced from 1.01 to 0.356.In addition,this design also has good robustness,that is,under a certain detuning between quantum dot and cavity,sub-Poissonian light can still be generated in the cavity.