Mixing of two-electron spin states in a semiconductor quantum dot

TL;DR

This paper demonstrates that asymmetric exchange interactions in semiconductor quantum dots can significantly mix two-electron spin states, affecting spin dynamics and light polarization, with implications for quantum information processing.

Contribution

It reveals the magnitude of asymmetric exchange effects on two-electron spin states and their role in spin dynamics within quantum dots, a novel insight in the field.

Findings

Asymmetric exchange can be as large as 50% of isotropic exchange.

Spin mixing influences light polarization reversal.

Electron spin couples strongly to orbital motion in quantum dots.

Abstract

We show that the low lying spin states of two electrons in a semiconductor quantum dot can be strongly mixed by electron-electron asymmetric exchange. This mixing is generated by the coupling of electron spin to its orbital motion and to the relative orbital motion of the two electrons. The asymmetric exchange can be as large as 50% of the isotropic exchange, even for cylindrical quantum dots. The resulting spin mixing contributes to understanding spin dynamics in quantum dots, including light polarization reversal.