Photonic Frequency Conversion With Periodically-poled Lithium Niobate Waveguide Module Based On Quasi-phase Matching

Quantum repeater is an important part of quantum network and atomic memory is one of the important candidates for constructing quantum repeater.The carrier of quantum information transmission is the photons,so that the ability to effectively transmit quantum states between photons of different frequencies is a key requirement for the realization of fiber-optic quantum networks.It requires the exchange of photons between quantum systems that emit or absorb photons with different wavelengths to link two quantum nodes.However,the frequency of photons directly emitted by common quantum nodes such as single atom,single molecule,single ion,single quantum dot and single NV color center is in near-infrared band,which has great loss in fiber channel and is not suitable for transmission in fiber.In order to be able to connect two different quantum nodes,bridging the gap between atomic memory and fiber optic communication,quantum frequency conversion technology is essential.The frequency of the photon directly emitted by the quantum node is converted into the photon of the communication band,which is transmitted in the optical fiber channel.After reaching the next node,the photon of the communication band is again converted into the photon near infrared band.In the whole process,the information complete transmission between different quantum nodes and form a quantum network.In this master thesis,the nonlinear optical effect is applied in the photonic quantum frequency conversion.The periodically poled lithium niobate(PPLN)waveguide is employed to realize frequency conversion of 852 nm photon corresponding to the D2 line of Cs atoms to 1560 nm telecom C band photon and the upconversion of 1553 nm telecom C band photon to 780 nm photon of the D2 line of Rb atoms.In addition to the construction of quantum networks,frequency up-conversion technology can also be used to make high efficiency and low dark count single photon detectors near communication band.The common Si avalanche photodiode single photon detectors(APDs)with high quantum efficiency and dark count are only suitable for visible and near infrared bands.In the communication band of 1.5 micrometer wavelength,the most common single photon detector is In Ga As avalanche photodiode,which has very limited quantum efficiency and high dark count performance.Although the superconducting nanowire single photon detector(SNSPD)has been developed quickly for some time,on account of that requires liquid nitrogen cooling system,and is complex and bulky,it cannot be widely used.Therefore,the photons at the wavelength of 1.5 micrometer can be effectively converted to the visible or near-infrared band and can be detected by the silicon-based single photon detector.The signal-to-noise ratio(SNR)is an critical element in the construction of quantum networks and frequency up-conversion single photon detectors.Therefore,in this paper,we focus on the filtering noise.In experiment,according to the broad-band speltra characteristics of spontaneous parametric down conversion(SPDC)and spontaneous Raman scattering(SRS)spectrum broadband,a specific experimental scheme is designed to filter out the noise photos.This research is of great significance for the performance optimization of frequency conversion single photon detector and the quantum entanglement with high fidelity.