Realization of single photon source for quantum telecommunication

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Quantum information technology ( QIT ) is now attracting many people because of its functions that cannot be realized using conventional technologies. A single photon generator, that emits a single photon in each pulse, is indispensable device for the realization of QIT. Recent proposals had a problem that the average number of photons are less than 0.1 and too small for the real use.In this research project, we aimed to realize a real single photon generator, which emits single photons with high probability. Our method is to control the fast gating shutter for the signal photons using the detection signals of control photons. Our goal we aimed in the proposal was as follows: The realization of single photon source with more than 10kHz repetition rate, and also the single photon should be localized with in 1ns time window.In the 2-year-long project, we first performed the characterization of the twin photon beam source and also the design of the system of the single photon source. In the second year, we succeeded in the development of the 'high-speed high-transmittance optical shutter' and 'optical delay line with high-transmittance.' We had almost finished the construction of the whole experimental system, however, the sudden accident of the trouble of the pump Argon ion laser caused the delay of the experiment unfortunately. After the end of the project (2002.3), we continued this experiment partly supported by JST-PRESTO project. In conclusion, we succeeded to perform the experiment which clearly showed the highest probability (0.4) to create single photons in a pulse, and in the experiment we observed a very small timing fluctuation less than 1ns, those are the goal we aimed in the proposal.