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Research Of The Filter In Optical Storage Experiment

Posted on:2014-07-25Degree:MasterType:Thesis
Country:ChinaCandidate:H L LiuFull Text:PDF
GTID:2268330401462473Subject:Atomic and molecular physics
Abstract/Summary:PDF Full Text Request
In recent years, quantum information storage is a hot research topic in the field of quantum information science, using electromagnetically induced transparency (EIT) effect of optical quantum information storage to atomic medium is more universal attention caused the scientific community at home and abroad. In this field, the detection of weak signal light is an unavoidable problem, how to eliminate the effect of background light on signal light, improving the signal-to-noise ratio and the sensitivity plays a vital role in the whole system. Therefore, we need to eliminate the interference of background light by inserting filter device in the detection system. In the atomic storage experiment, the discrepant frequency between signal light and the background light is about several GHz, that means we need the filter has high transmissivity and narrow bandwidth to signal light.This paper first introduces the dynamic-process of EIT effect and the storage and release of quantum information by EIT effect, and put forward the problem in extracting the storage signal; then introduces the two kinds of filter with different filter theory:Rb medium filter and F-P interference filter. Through the theoretical calculation and experimental research, analysis the advantages and disadvantages of two kinds of filter, and sum up the different application range of them. This paper introduces the concrete work includes the following content:(1) We simply introduce the basic kinetics process of the EIT and the cold atoms trapping, and present the detail of the storage and release of optical quantum information by EIT effect. We have found that in the experiment:the angle of the propagation direction between the coupling light and the probe light will affect the time of the quantum information storage in the cold atomic medium significantly, the higher of the overlap degree, the longer storage life will be, as well as a higher storage efficiency, but it is difficult in extracting weak storage signal and analyzing of experimental results.(2) We select the appropriate level structure for theoretical calculations of the Rb medium filter, analyze the possibility by fitting the calculated results, and then verify its feasibility by experiments. In the experiment, the signal light and the pump light goes through the high temperature Rb medium, and we studied the absorption and transmission of the signal light which is locked in different transition line. It turned out that:the pump light with its frequency tuned to the resonance transition F=1â†'F’=2of Rb medium D2line pump the atom by appropriate temperature control structure, so the atom is prepared to energy level F=2, such polarized atoms can bring about the selective transmission of the probe light and the coupling light in the experiment of the storage and release of optical quantum information, and meet the filtering requirement.(3) We introduce the fundamental principle and the structure of the F-P interference filter briefly, and make some analysis of its important performance index, and then derive the important parameters of the F-P interference filter in theory, and present the detail of the F-P interference filter structure we have used and improved. It turned out that, the stability of improved structure F-P interference filter’s mechanical structure and temperature is improved obviously. In order to meet the requirements of filter in the storage and release of optical quantum information on the single photon level, we put forward the concept of F-P etalon filter system, and demonstrate effectiveness of the filter system by experimental test.
Keywords/Search Tags:electromagnetically induced transparency effect, Rb atomic filter, F-Pinterference filter
PDF Full Text Request
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