Full counting statistics of interacting quantum dots contacted by a normal metal and a superconductor

TL;DR

This paper studies how Coulomb interactions influence charge transfer in a quantum dot connected to a normal metal and a superconductor, revealing unique behaviors at different voltage regimes and the emergence of quartets.

Contribution

It introduces a detailed analysis of Coulomb effects on full counting statistics in hybrid quantum dot systems, highlighting novel phenomena like quartets at low voltages.

Findings

Charge transfer behavior differs significantly at voltages below and above the superconducting gap.

Superconducting correlations cause the appearance of quartets due to onsite Coulomb interactions.

Normal charge doubling is replaced by more complex transfer processes at low voltages.

Abstract

We investigate the effects of Coulomb interaction on charge transfer through a quantum dot attached to a normal and a superconducting lead. While for voltages much larger than the gap we recover the usual result for normal conductors, for voltages much smaller than the gap superconducting correlations lead to a drastically different behavior. Especially, the usual charge doubling in the normal case is reflected in the occurence of quartets due to the onsite interaction.