Competing interactions in semiconductor quantum dots

TL;DR

This paper develops an integrability-based approach to study decoherence in semiconductor quantum dots, considering hyperfine and dipole-dipole interactions, revealing their combined effects across different magnetic field regimes.

Contribution

It introduces a novel method to analyze the interplay of hyperfine and dipole-dipole interactions in quantum dot decoherence, including mean-field treatment of dipolar effects.

Findings

Hyperfine interaction dominates short-time decoherence at low fields.

Dipole-dipole interactions dominate at high fields.

Mean-field dipolar interactions eliminate the non-decaying fraction in zero-field free induction decay.

Abstract

We introduce an integrability-based method enabling the study of semiconductor quantum dot models incorporating both the full hyperfine interaction as well as a mean-field treatment of dipole-dipole interactions in the nuclear spin bath. By performing free induction decay and spin echo simulations we characterize the combined effect of both types of interactions on the decoherence of the electron spin, for external fields ranging from low to high values. We show that for spin echo simulations the hyperfine interaction is the dominant source of decoherence at short times for low fields, and competes with the dipole-dipole interactions at longer times. On the contrary, at high fields the main source of decay is due to the dipole-dipole interactions. In the latter regime an asymmetry in the echo is observed. Furthermore, the non-decaying fraction previously observed for zero field free induction decay simulations in quantum dots with only hyperfine interactions, is destroyed for longer times by the mean-field treatment of the dipolar interactions.