Influence of the pair coherence on the charge tunneling through a quantum dot connected to a superconducting lead

TL;DR

This paper investigates how the coherence of electron pairs affects charge tunneling through a quantum dot connected to normal and high-temperature superconducting leads, highlighting qualitative changes in current near the superconducting transition.

Contribution

It provides a qualitative analysis of the impact of electron pair coherence on charge transport in a quantum dot system with high-Tc superconductors, without relying on a specific microscopic model.

Findings

Coherent electron pairs significantly alter charge current behavior.

Incoherent pairs lead to different tunneling characteristics.

The study highlights the role of pair coherence near T_c.

Abstract

We analyze the charge transport through a single level quantum dot coupled to a normal (N) and superconducting (S) leads where the electron pairs exist either as the coherent (for temperatures below T_c) or incoherent objects (in a region T_c < T < T*). This situation can be achieved in practice if one uses the high T_c superconducting material where various precursor effects have been observed upon approaching $T_{c}$ from above. Without restricting to any particular microscopic mechanism we investigate some qualitative changes of the nonequilibrium charge current caused by the electron pair coherence.