Effect of Coulomb Blockade on Josephson Super Current Across Superconductor/Quantum Dot/Superconductor Nano Junction
A. Dhyani, P. Dua, A.K. Chawla and B.S. Tewari*
Department of Physics, University of Petroleum and Energy Studies, Dehradun, Uttarakhand, India.
*E-mail:-bstewari@ddn.upes.ac.in
The present paper deals with the study of Josephson supercurrent across the correlated single level quantum dot sandwiched between two s-wave superconductors. The renormalized Anderson model is used that includes in the Hamiltonian contribution corresponding to the correlated superconducting quantum dot state, effective BCS type attractive interaction in the superconducting leads, the electron tunneling energy term responsible for coupling of superconducting leads with the dot energy level thatrepresents the tunneling of Cooper pair between two superconductors and on-dot coulomb energy to take care of electronic correlations. The Green’s function equations of motion technique are employed within the framework of Ambegaokar-Baratoff approach to analyze the Josephson supercurrent across such junction. It is pointed out that for large value of on-dot Coulomb energy, the Josephson supercurrent across superconducting Quantum dot (S-QD-S) junction decreases.
Keywords: Josephson supercurrent, Quantum dot, Electron tunneling, Cooper pair, Superconductivity, Nanoscopic junction.
