Triplet-Singlet Spin Relaxation via Nuclei in a Double Quantum Dot

TL;DR

This paper investigates electron spin relaxation in a GaAs double quantum dot, revealing that nuclear interactions dominate spin flips and are significantly slowed by small magnetic fields, impacting spin-based quantum information processing.

Contribution

It provides detailed time domain measurements of spin relaxation for arbitrary spin state splittings, highlighting the dominant role of nuclear interactions in electron spin flips.

Findings

Nuclear interactions dominate electron spin relaxation.

Applying a small magnetic field significantly slows spin flips.

Results have implications for spin-based quantum information processing.

Abstract

The spin of a confined electron, when oriented originally in some direction, will lose memory of that orientation after some time. Physical mechanisms leading to this relaxation of spin memory typically involve either coupling of the electron spin to its orbital motion or to nuclear spins. Relaxation of confined electron spin has been previously measured only for Zeeman or exchange split spin states, where spin-orbit effects dominate relaxation, while spin flips due to nuclei have been observed in optical spectroscopy studies. Using an isolated GaAs double quantum dot defined by electrostatic gates and direct time domain measurements, we investigate in detail spin relaxation for arbitrary splitting of spin states. Results demonstrate that electron spin flips are dominated by nuclear interactions and are slowed by several orders of magnitude when a magnetic field of a few millitesla is applied. These results have significant implications for spin-based information processing.