Numerical renormalization group approach to a quantum dot coupled to normal and superconducting leads

作者：Tanaka Yoichi^*; Kawakami Norio; Oguri Akira

来源：Journal of the Physical Society of Japan, 2007, 76(7): 074701.

DOI：10.1143/JPSJ.074701

• quantum dot
• Andreev reflection
• Kondo effect
• numerical renormalization group method

We study transport through a quantum dot coupled to normal and superconducting leads using the numerical renormalization group method. We show that the low-energy properties of the system are described by the local Fermi liquid theory despite of the superconducting correlations penetrated into the dot due to a proximity effect. We calculate the linear conductance due to the Andreev reflection in the presence of the Coulomb interaction. It is demonstrated that the maximum structure appearing in the conductance clearly characterizes a crossover between two distinct spin-singlet ground states, i.e. the superconducting singlet state and the Kondo singlet state. It is further elucidated that the gate-voltage dependence of the conductance shows different behavior in the superconducting singlet region from that in the Kondo singlet region.

• 出版日期2007-7