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[2]Transport Properties of Mesoscopic Quantum Devices:
In this thesis, three models of mesoscopic device are proposed: (i) a quantum dot is coupled to two superconducting leads via a quantum point contact, (ii) a quantum dot is coupled weakly to two superconducting leads via tunnel barriers, (iii) an electron stub tuner modeled as S-Sm-S-Sm-S (S-superconductor, Sm- semiconductor). Quantum transport characteristics of such three systems are studied under the effect of Coulomb blockade and magnetic field. The Josephson current has been obtained in terms of the Andreev-reflection amplitude. This amplitude was deduced by solving the Bogoliubov-deGennes equation. For the first model, the coherent property of the junction is deduced from the variation of the current with the phase angle of Cooper pair. While for the second model, the current-phase angle relationship exhibit a peak under the effect of magnetic field and temperature. A periodic variation of the current with the phase angle is observed for the third model.
