Role of Nuclear Quadrupole Coupling on Decoherence and Relaxation of Central Spins in Quantum Dots

TL;DR

This paper develops a theory on how nuclear quadrupole coupling affects the decoherence and relaxation of central spins in quantum dots, showing that strong QC can significantly accelerate spin relaxation, aligning with experimental observations.

Contribution

The paper introduces a theoretical framework for nuclear quadrupole coupling's impact on central spin dynamics in quantum dots, highlighting its role in spin relaxation processes.

Findings

Quadrupolar coupling can exponentially enhance spin relaxation rates.

Strong QC effects are comparable to hyperfine interactions in quantum dots.

The theory aligns well with recent experimental data on hole spins.

Abstract

Strain-induced gradients of local electric fields in semiconductor quantum dots can couple to the quadrupole moments of nuclear spins. We develop a theory describing the influence of this quadrupolar coupling (QC) on the spin correlators of electron and hole "central" spins localized in such dots. We show that when the QC strength is comparable to or larger than the hyperfine coupling strength between nuclei and the central spin, the relaxation rate of the central spin is strongly enhanced and can be exponential. We demonstrate a good agreement with recent experiments on spin relaxation in hole-doped (In,Ga)As self-assembled quantum dots.