The Transfer Of Coherence Between Two Memory Channel Via Raman Process

In recent years, due to the quantum interference effect occurs of the interaction coherent and multi-level atoms, which will produce a variety of interesting physical phenomena. So the interaction of optice and atomic has become an important research in physics that is given attention. One effect of electromagnetically induced induced transparency (EIT) can decrease the absorption and dispersion increased, reduced the group velocity of optical pulses is compressed into the atomic medium,which has been widely research in thepry and experiment. Among them, the electromagnetically induced transparency(EIT),coherent layout trapping (CPT), Raman two-photon process, stimulate Raman adiabatic passage, spontaneous emission control, resonance-enhanced nonlinear optical quantum storage are based on atomic coherence.In1995, the Harris team of Stanford University use of electromagnetically induced transparency technology to light pulse group velocity slows down, and to165m/s, the research in the rubidium atoms of the gas chamber, in1999, the Hau team observed the phenomenon of the light pulse, and by EIT effect will slow down the light pulse group velocity to17m/s, the research in ultracold Na atom BEC, then They achieve the light field of information stored in the atomic ensemble and controlled release, on the basis of light deceleration. in recent years,the EIT effect has been found application in light speed reduction, optical quantum storage, generation of nonclassical light, realization of the entanglement between light and atoms.This dissertation introduces the relationship between the efficiency of coherence transfer in two-channel and single-photon detuning, intensity of Raman laser. In a four-level system, we store a coherent optical signal in an initial channel by using EIT technology. Then we implement coherence transfer between two memory channels, by Raman two-photon transition. Then comparison of the relationship between gaussian and square wave of Raman laser, we obtain the maximum efficiency of coherence transfer along with the function of the gaussian of Raman laser is about94%. 1) Fristly. considering theA-type three-level atomic structure, the theory of the absorption and dispersion was analyzed by the semi-classical interaction caused by light and atom, which was induced by KIT effect. and the dynamic-process of KIT effect, the storage and releasion of quantum information were analyzed in theoretical.2) Secondly, we put the signal light beam into the cold87Rb atom by the FIT effect, the signal light will be stored or released in the cold-atomic medium when the light was stored into the superposition of the two base state of the atom.