The Property Of Quantum Noise In Coherent Atomic System

The atomic coherence of the interaction of light and atom opens a new way to quantum computation and quantum communication, and it is one of important methods for quantum information storage. The research indicated recently that light is the reliable carrier of transmitting and processing quantum information. But, because of the fast propagation velocity, photons can't be stored for long, and manipulation collective photon state present considerable difficulties. However, whether the traditional computer or the future quantum computer, both need the certain space to store the processing information. At present, it is well known that material particles such as atoms are stable, the qubits of which are called static qubit, thus Particles provide reliable quantum information storage. And the coherent interaction of light and atoms has provided the effective way for quantum information transmission exactly from the quantum state of light field to the quantum state of particles. Therefore the realization of the quantum state transmission, storage and read-out via the interation of light and atoms will show a vital significance to the development of quantum computation and quantum communication. In the process of quantum information memory and transmission, the quantum noise of light field will have the certain influence on the SNR (Signal to Noise Ratio) of information read-out. How to restrain the effect of quantum noise on quantum information memory will improve SNR, information security, and information capability. On the other hand, due to the characteristic of higher dispersion in the atomic coherent medium, the research of quantum noise properties of light also indirectly provide a method to measure the phase noise of light field. In this thesis, we discuss the quantum noise properties of the probe light interacting with atomic coherent medium. The result shows that the quantum noise in the coherent mediem shows the following characteristics: firstly, it can transform the intrinsic phase noise as the observable intensity noise, make the operation simple, and be expected to product for the small integrated commercialization; secondly,...