Development of waveform observation system with 1ps time resolution and 100 micron specific resolution

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The purpose of this study is to develop the waveform observation system with a few picosecond time resolution and a few hundred micron specific resolution. Moreover, microwave propagation properties are analyzed by using the system.(1) [High quality Josephson junctions] It was found that the impurities in the electrodes caused reduction of the superconducting order parameter. We could developed the preparation process of the ideal-like Josephson junctions by increasing the deposition rate of Nb. In addition, the oxidation mechanism was found from the dependence of the critical current density on the oxidation gas pressure.(2) [Waveform observation system] We have developed the waveform observation system with 10ps time resolution and 10muA current sensitivity, which was achieved by reducing the external noise and matching the impedance between Josephson junction circuits and external electronics.(3) [Microwave observation system] We have measured the surface impedance of Nb and AI films by using the system. The experimental results agreed well with the theoretical values based on the BCS theory. The surface resistance of Y-Ba-Cu-0 high Tc superconducting films is under investigation.