Revealing attractive electron-electron interaction in a quantum dot by full counting statistics

TL;DR

This paper demonstrates that attractive electron-electron interactions in a quantum dot significantly alter the full counting statistics of electron transfer, revealing stronger correlations than repulsive interactions, even with rapid spin relaxation.

Contribution

It introduces a method to distinguish attractive from repulsive interactions in quantum dots via full counting statistics analysis.

Findings

Attractive interactions cause distinct signatures in factorial cumulants.

Higher-order cumulants reveal stronger correlations with attraction.

Signatures persist despite fast spin relaxation.

Abstract

Recent experiments [Nature 521, 196 (2015) and Nat. Commun. 8, 395 (2017)] have presented evidence for electron pairing in a quantum dot beyond the superconducting regime. Here, we show that the impact of an attractive electron-electron interaction on the full counting statistics of electron transfer through a quantum dot is qualitatively different from the case of a repulsive interaction. In particular, the sign of higher-order (generalized) factorial cumulants reveals more pronounced correlations, which even survive in the limit of fast spin relaxation.