Research On Luminescence Characteristics Of Coupled Quantum System

The increasing demand for information processing technology motivates the rapid development of quantum information science.Quantum light source,an indispensable and important part for quantum information technology,is widely studied.Based on cavity quantum electrodynamics,we focus our research on the quantum light source in this thesis.We explore the luminescence characteristics of solid-state coupled quantum system,design an integrated chip-sclae entangled photon-pair source,and experimentally realize high-dimensional quantum entanglement utilizing quantum light source.The main contents and innovations of this thesis are as follow:1.A scheme to realize unconventional photon blockade by means of a photonic molecule is theoretically proposed.The photonic molecule consists two coupled optical microcavities,one of which contains a quantum dot.The strong photon antibunching can be achieved by unconventional photon blockade with moderate quantum dot-cavity coupling strength under continuous wave laser excitation,the zero-delay second-order correlation function can be as low as g2(0)?10-4.When the system is driven by two laser fields,by optimizing the relative phase between the two driving laser fields,strong photon antibunching with relative large intracavity photon number can be achieved with lower tunneling strength than the single laser driving scenario.The proposed photonic molecule system can maintain strong photon antibunching within a large parameter variation under the optimal phase condition,showing a strong robustness of the system.2.We theoretically propose a quantum light source scheme that integrates single photon emission with two-photon emission by means of a four-level QD-bimodal cavity system.Thanks to the diamond type four-level energy structure of the QD,we manage to excite the single-photon and two-photon transitions separately in the same system.Utilizing coherent excitation,we can tune and optimize the single-photon and two-photon resonances of the coupling system by adjusting the frequency detuning between the driving laser fields and cavity mode and also the excitation intensity ratio r of the two driving laser fields.The system can achieve optimal single photon emission,with the zero delay second-order correlation function ga2(0)?0.15 and the intracavity photon number around 0.01.The effect of frequency splitting between two cavity modes on single photon emission is evaluated,the system can maintain photon antibunching within the fabrication error range of 2.4 GHz for the frequency of cavity mode a.The system can realize two-photon emission with the Mandel parameter Q=0.04 and the intracavity photon number around 0.01.3.A new hybrid quasi-phase-matching waveguide structure of Si-rich nitride(SixNy)waveguide and thin film PPLN for generating high-purity SPDC photons is designed,which enables multifunctional chip-scale and wafer-level integration.By using SixNy,the reflection loss can be reduced at between the waveguide and the LN film.By tuning the waveguide width and optimizing refractive index of SixNy,optical modes can be tightly confined in PPLN region of designed hybrid waveguide structure.The hybrid waveguide device shows a peak normalized efficiency of 225%W-1·cm-2 at 1560nm for second harmonic generation.The phase matching condition is then optimized by tuning the pump and the length of the PPLN to achieve biphoton state with a high purity of 95.17%.The hybrid waveguide is then served as entangled photon source to generate high-dimensional biphoton frequency comb,Hong-Ou-Mandel quantum revival is theoretically predicted with visibility up to 99.67%.By numerical simulation,Two-photon interference dips at 33 times-bins are predicted with over 50%visibility,equivalent to?5 qubits per photon for high-dimensional entanglement.4.Experimental scheme of polarization and energy-time high-dimensional hyperentanglement through a biphoton frequency comb is proposed and demonstrated.A bright two-photon frequency comb with 5 qubits per photon encoding is realized by using the type ? entangled photon pairs generated by ppKTP waveguide.The energy-time entanglement of the high-dimensional biphoton frequency comb is characterized by Hong-Ou-Mandel interferometer,with quantum revival of 10 time-bins observed.The visibility of the two-photon interference of the central time-bin is measured to be 99.5%.Polarization entanglement is generated by mixing biphoton frequency comb on a 50:50 fiber beam splitter.The interference fringes of polarization entanglement are obtained by projection measurement using polarization analyzer,with fringe visibility measured to be 98.46± 0.36%and 98.06± 0.34%for different polarization subspaces,respectively.According to the interference fringes,the CHSH S parameter is calculated to be 2.7416±0.031,with Bell inequality violation up to 23.9 standard deviations.The research of this thesis can be useful for the development and practical implementation of quantum light sources,and provide guidance for future applications of dense quantum encoding and high-dimensional quantum communication.