Nuclear spin diffusion in the central spin system of a GaAs/AlGaAs quantum dot

TL;DR

This study demonstrates that in GaAs/AlGaAs quantum dots, electron spins accelerate nuclear spin diffusion through spin-flip fluctuations, challenging previous theories and offering potential for quantum information storage.

Contribution

The paper provides experimental evidence that electron spins accelerate nuclear spin diffusion in quantum dots, contradicting earlier predictions of a barrier formation.

Findings

Electron spins accelerate nuclear spin diffusion in quantum dots.

Acceleration persists at high magnetic fields due to spin-flip fluctuations.

Nuclear spin lifetimes range from 1 to 10 seconds, suitable for quantum information applications.

Abstract

The spin diffusion concept provides a classical description of a purely quantum-mechanical evolution in inhomogeneously polarized many-body systems such as nuclear spin lattices. The central spin of a localized electron alters nuclear spin diffusion in a way that is still poorly understood. In contrast to previous predictions, we show experimentally that in GaAs/AlGaAs quantum dots the electron spin accelerates nuclear spin diffusion, without forming any Knight field gradient barrier. Such acceleration is present even at high magnetic fields, which we explain as a result of electron spin-flip fluctuations. Diffusion-limited nuclear spin lifetimes range between 1 and 10 s, providing plenty of room for recent proposals seeking to store and process quantum information using quantum dot nuclear spins.