Influence Of Phase-sensitive Manipulation And Coherent Feedback Control On Entanglement Enhancement

Quantum information is a new cross discipline of quantum mechanics and information theory, and attracts more and more researchers’attention due to the fast computation and secure communication, which can be realized in classical information. The continuous variable entangled state of light is basic resources of quantum information and has been widely used. In order to achieve high-quality and long-distance quantum communication, the entangled states of light with high entanglement degree should be prepared firstly. Non-degenerate optical parametric amplifier (NOPA) is one of the effective means to generate EPR entangled states of light. However, due to the constraints of optical components and crystal, improvement of entanglement degree of EPR entangled state, which only through a single NOPA can’t satisfy the application requirements. So it is important to enhance entanglement degree of EPR entangled state by other method. In this paper, we respectively discuss influence of phase-sensitive manipulation and coherent feedback control on entanglement enhancement. This will provides a new choice for the generation of EPR entangled states with high entanglement degree, which will be useful for the development of quantum information in the future.In this paper, the main contents include:(1) We analysis influence of parameters of NOPA on the effect of the entanglement enhancement, which is used phase-sensitive manipulating the EPR entangled states of light. We also give a description of the experiment about the cascaded entanglement enhancement of EPR entangled states by using three NOPA.(2) We analysis influence of parameters of coherent feedback system on entanglement enhancement of the EPR entangled states optical fields. This will provides reference for further experimental research.