High efficient single photon source based on photonic molecule with low tunneling strength containing a quantum dot

Based on the quantum dot-photon molecular coupling system, we proposed an efficient and stable single photon source. The system uses photon molecules formed by the coupling of two optical microcavities A and B, one of which contains a quantum dot. The 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 (0.25κ<g<κ) and at low cavity tunneling strength (J≧0.5κ) as well. It also has excellent robustness and is easy to construct. Under the optimal experimental parameters that can be realized, the zero-delay second-order correlation function g2(0) of the system can be as low as 10−5 with a relatively large intra cavity photon number. 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 easier 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.