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The Scientific World Journal
Volume 2014, Article ID 721671, 19 pages
Research Article

Single Charge Current in a Normal Mesoscopic Region Attached to Superconductor Leads via a Coupled Poisson Nonequilibrium Green Function Formalism

1Laboratorio de Física Teórica de Sólidos (LFTS), Centro de Física Teórica y Computacional (CEFITEC), Facultad de Ciencias, Universidad Central de Venezuela, A.P. 47586, Caracas 1041-A, Venezuela
2Departamento de Física, Universidad Simón Bolívar, A.P. 89000, Caracas 1080-A, Venezuela

Received 31 August 2013; Accepted 30 October 2013; Published 9 April 2014

Academic Editors: A. Ovchinnikov and A. Savchuk

Copyright © 2014 David Verrilli et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We study the I-V characteristic of mesoscopic systems or quantum dot (QD) attached to a pair of superconducting leads. Interaction effects in the QD are considered through the charging energy of the QD; that is, the treatment of current transport under a voltage bias is performed within a coupled Poisson nonequilibrium Green function (PNEGF) formalism. We derive the expression for the current in full generality but consider only the regime where transport occurs only via a single particle current. We show for this case and for various charging energies values and associated capacitances of the QD the effect on the I-V characteristic. Also the influence of the coupling constants on the I-V characteristic is investigated. Our approach puts forward a novel interpretation of experiments in the strong Coulomb regime.