High Efficient Single Photon Source Based On Quantum Dot-microcavity Coupling System

With the development of quantum technology and the continuous improvement of quantum theory,it is a promising research direction to find a better quantum information processing scheme.Among them,the realization of efficient and stable integrated quantum light source is a key problem that needs to be solved urgently.Semiconductor quantum dots have attracted attention in recent years due to their simple implementation characteristic,ease of integration,and potential large-scale application value.Therefore,single photon sources using semiconductor quantum dot are the hotspots of current research.In this paper,Based on the quantum dot-photon molecular and the quantum dot-cavity array coupling system,we proposed two schemes to create an efficient and stable single photon source.The main works and innovations are as follows:1.High efficient single photon source based on photonic molecule with low tunneling strength containing a quantum dot is studied.The system uses photon molecules formed by the coupling of two optical microcavities A and B,one of which contains a quantum dot.The continue wave excitation laser act on the quantum dot in cavity A,and through the interaction between the light field in cavity A and cavity B,single photon is generated in cavity B and output extraction is performed therein.The system maintains good sub-Poisson characteristics over a wide range of dot-cavity coupling strength variation(0.25k<g<k)and at low cavity tunneling strength(J(?)0.5 k)as well.It also has excellent robustness and is easy to construct.Under the optimum experimental parameters,the zero-delay second-order correlation function of the system is close to 10-7 with a relatively large cavity output(0.25counts/ns).Under the scheme proposed in this paper,the single photon purity and output intensity can be balanced,and the single photon output can reach 1.1 counts per nanosecond,while the single photon purity can be guaranteed to reach g2(0)<10-5.We theoretically explains the reason why the system produces sub-Poisson light,and analyzed the impact of system parameters change.Meanwhile,the system spatially separates the output light from the excitation light,making it easy to extract single photons,and has potential application value for large integration.The model proposed in this paper will bring important guiding value to the efficient and integrated single photon sources in future quantum information processing.2.Further more we studied the performance of a system that a single quantum dot coupled to an cavity array formed by three coupling cavities A and B and C with a continue wave excitation laser act on the dot.The quantum dot is in cavity A,and cavity A is adjacent to cavity B and not adjacent to cavity C.Single photon output can be obtained in cavity B as well as cavity C,but the purity of single photon in cavity C is low,so we extract single photon in cavity B.The results show that the introduction of an additional cavity can make the system produce single photon with higher purity than the single photon source designed in Chapter 3 to a certain extent,and under some parameters range,super Poisson light can be obtained from the system.The disadvantage of this system is that it is more complex in structure and the efficiency of single photon generation is slightly worse than that of the system proposed in Chapter 3.When some quantum optical processes require higher single photon purity,the proposed model can be used to construct single photon sources.