Research Of Quantum Amplification Based On Imperfect Auxiliary Photon Source

Quantum mechanics is one of the three basic theories of physics and it brings many advanced technologies for human society. Quantum information is a new emerging interdisciplinary of quantum mechanics and information science, involving quantum computer and quantum communication and so on. Quantum information becomes an important field of current information researches because of its scientific significance and great prospects.The single photon is the basic building block in quantum information, and entanglement is also a vital resource in quantum information processing. However, quantum systems always interact with the outside environment. The single photon and entanglement are sensitive to the environmental noise. It will lead to photon loss and quantum decoherence. These problems seriously limit the practical application. To overcome the problem, the concept of quantum amplification has been proposed. It is an effective way to protect the single photon state and entangled state. In recently years, many works of quantum amplification have been done.In this paper, serval classical models of quantum amplification are studied and a conclusion is made. Then this paper presents several amplification schemes to implement practical quantum applications. The first work is the quantum amplification research with imperfect auxiliary single photon. A scheme which use imperfect single photon as auxiliary source is investigated to protect the single photon in practical, and this scheme is extend to protect the single-photon entangled state and single-photon W state. The second work is the amplification research of single photon with imperfect auxiliary entanglement source. In this scheme, we consider both the spatial and polarization information of the single photon. Compared with the first scheme, this protocol not only can increase the fidelity of single photon state, but also can protect the information encoded in the polarization degree of freedom. The imperfect auxiliary source is practical SPDC source. It is improved that the amplification using entanglement as auxiliary is more effective than that using single photon as auxiliary. The third work is the amplification of single-photon entangled state with imperfect auxiliary entanglement source. By performing numerical simulation and discussion, the three protocols may be useful in practical quantum communication and quantum information processing.