Realization Of Quantum Network And Nonlinear Beamsplitter Based On Four-wave Mixing

This thesis presents a study of the four-wave mixing (FWM) process in hot Rubid-ium vapor and its application to construct quantum network and nonlinear beamsplitter. FWM is an efficient X(3) nonlinear process, involving a double Raman scattering event, where conservation of energy and momentum entangle these Raman scattered photons. This process has already been used as a resource for multimode quantum state genera-tion and which has been proved to be a promising candidate for applications to quantum information processing.We propose a scheme to realize versatile quantum networks by cascading several FWM processes in warm rubidium vapors. We analyze theoretically the multimode output of cascaded FWM systems, derive its independent squeezed modes and show how, with phase controlled homodyne detection and digital post-processing, they can be turned into a versatile source of continuous variable cluster states.We experimentally implement a nonlinear beamsplitter using a phase-sensitive para-metric amplifier, which is based on FWM in hot rubidium vapor. Here we show that, despite the different frequencies of the two input beams, the output ports of the non-linear beamsplitter exhibit interference phenomena. We make measurements of the interference fringe visibility and study how various parameters such as the intensity gain of the amplifier, the intensity ratio of the two input beams, the one and two pho-ton detunings, affect the behavior of the nonlinear beamsplitter. It may find potential applications in quantum metrology and quantum information processing.