| Built on the foundation of information science and quantum mechanics,quantum information science has developed in two aspects:On one hand,quantum information science aims to encode the information to the quantum systems,and utilizes the special-ties of qubits,such as quantum coherence and entanglement,to realize the extension of the information-process dimensions.Lots of novel information-process methods like quantum communication and quantum computation have been derived in this way;On the other hand,quantum information science aims to make a insightful interpretation for the quantum world in the view of information science.By quantifying the quan-tum physical properties like quantum coherence and nonlocality,and putting forward to quantum resource theory,Bell’s theorem and so on,quantum information science pro-vides the deeper insights for quantum physics and quantum systems further.The two aspects of quantum information science are complementary and have played important roles in the researches of fundamental science and applied science with the development of the technology nowadays.The linear optical system takes the photon states like the polarization,path,etc.as the quantum information carriers,possesses the advantages of the long coherence time,multiple encoding dimensions and so on.It can be utilized to realize comprehensive ex-perimental investigations for various quantum-information processes.The followings are the main research works of my doctoral dissertation:1.Proposal for the entanglement enhancement based on the ultrafast param-eter downconversion process.We propose a proposal to realize the ultrafast time postselection and the parameter downconversion to the telecom bands for entangled photons emitted from quantum dots.By sending the entangled photons and narrow-pulsed laser to the periodic polarized nonlinear crystal simultaneously,the negative affect for the entanglement stemming from the fine-structure splitting of the intermediate energy lever in quantum dots can be reduced effectively.2.Investigation of the room-temperature single photon source based on two-dimensional material.Hexagonal boron nitride has the wide band gap of 6 eV,and the exciton bounded in its deep-defect level can not transit to be the free exciton by the phonon excitation.Therefore hexagonal boron nitride is a good candidate as the single-photon-source sys-tem.We processes the hexagonal boron nitride flake by high-temperature anneal and ion implantation,and realize the tentative preparation of the room-temperature single photon source based on hexagonal boron nitride.3.Quantum simulation of the parity-time symmetric quantum system and experimental investigation of no-signalling principle.We experimentally realize the nonlocal quantum simulator and simulate the parity-time symmetric quantum system using the linear optical system,by distributing an en-tangled photon pair to the space-like separated parties.We also experimentally inves-tigate no-signalling principle in the parity-time symmetric quantum system,and the phenomenon of superluminal information spreading in the specified conditions.4.Realization of the power-recycling weak-value-based metrology beyond shot-noise limit.We combine the optical-cavity-enhanced system and weak-value-based metrology,realize the recycling of the photons discarded by postselection in the weak-value-based metrology.The power-recycling weak-value-based metrology enhances the measure-ment precision,meanwhile holds the weak-value amplification effect,can surpass the shot-noise limit of the classical metrology.5.Realization of the rigorous measures of quantum coherence.We experimentally realize two kinds of rigorous measures of quantum coherence satisfying the resource-theoretic framework.The one is based on the conception of the robustness of quantum coherence,and the other is based on the physical observable corresponding to the robustness of coherence.The two methods are both explicit and robust to quantify quantum coherence. |
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