Preparation And Storage Of Frequency-Uncorrelated Entangled Photons From Cavity-Enhanced SPDC

The present dissertation discusses in detail the experimental preparation of nar-rowband polarization-entangled photons and its application in atomic-ensemble-basedquantum memories.Experimentallybymakinguseofthecavity-enhancedspontaneousparametricdown-conversion, wesetupafrequency-tunablesourceofnarrowbandpolarization-entangledphotons. Frequency-correlationbetweenentangled-photonpairisremovedbychangingthe pump beam from continuous-wave to be pulsed with a suitable width. NarrowbandPolarization-entangled photon sources of high quality is generated.With this narrowband entanglement source, we first send one photon of each pairinto a cloud of 87Rb atoms which are captured from a dark magneto-optical trap(MOT),by making use of the electromagnetically-induced-transparency(EIT) technique, wesuccessfully realized the storage of this narrowband entanglement source. Our workdemonstrates a quantum interface between frequency-uncorrelated spontaneous para-metric down-conversion photons with an atomic quantum memory for the first time. Ina second experiment, we send both photons to the same atomic ensemble, by makinguse of more spatial mode, we realize the storage of both photons of narrowband en-tangled photon pair simultaneously. This is for-the-first-time experimental storage of atwo-photon entangled state in an atomic ensemble.We believe, the techniques developed in this dissertation would dramatically facil-itate progresses in many fields, including long distance quantum communication, scal-ablelinearopticquantumcomputationandtestofthefoundationofquantummechanics.