The Modulation And Emission Of Photon Source Based On Quantum Dot Coupled With Microcavities

Single photon plays an important role in quantum key distribution,quantum teleportation and quantum secure communication. The realization of efficient solid-state quantum light source is an urgent problem to be solved in quantum information science. In the classical J-C model, the generation of single photon mainly depends on the split of energy level in strong coupling regime between quantum dot and microcavity. Driven by continuous wave laser, the single photon is resonant,while the multiphoton is detuned. In this paper, we demonstrate the emission of single photon under the conditions of low coupling strength, low nonlinearity and low tunneling strength based on quantum destructive interference. At the same time, we improve the photon number intensity. The photon antibunching induced by quantum destructive interference is theoretically demonstrated based on a photonic molecule consisting of two photonic nanocavities and a quantum dot or the coupled microcavity with second nonlinearity.At first, we demonstrate the photon state in the system of quantum dot coupled with two microcavities.Two driving conditions, single laser and double laser continuous wave driving, are investigated respectively.We can obtain extremely strong photon antibunching with under the situation that the system is driven by single laser, meaning that we can obtain pure single photon source.What is more, we also make a balance for this system to achieve high purity and high density single photon source. While the system is driven by double laser, the strong photon blockade can be achieved, and the QD-cavity coupling strength can be reduced to 0.1 8? by tuning relative phase between two laser driving fields,and a tunable strong photon blockade can be realized by modulating the QD-cavity coupling strength and the tunneling strength simultaneously.In both cases, We can obtain relatively large photon number in the strong photon blockade regime. Additionally, the situation of double laser driving can be more flexible and obtain more photon number compared with the situation of single laser driving. Thus this system can be used as an excellent device of single photon source.Secondly, we also demonstrated the generations of photon antibunching state in the second nonlinear microcavities. We couple an empty cavity with a second nonlinear cavity, and make the empty cavity emit single photon. Under the premise of empty cavity excitation, we study the two modes of excitation in the second order nonlinear cavity :the excitation of high frequency mode and the excitation of the fundamental mode. By modulating the ratio of two driving strength, we achieved unconventional photon blockade .The surprisingly low second correlation function (about 0.01)was obtained.This system can be used as single photon device without emitters.