Hole - Nuclear Spin Interaction in Quantum Dots

TL;DR

This study investigates hole spin dynamics in p-doped InAs/GaAs quantum dots, revealing hyperfine interactions as the main dephasing mechanism and showing that small magnetic fields can significantly reduce this dephasing.

Contribution

It provides the first detailed measurement of hole spin dephasing times and demonstrates the influence of nuclear hyperfine interactions and external magnetic fields on these times.

Findings

Hole spin dephasing time is approximately 15 ns without magnetic field.

Hyperfine interaction with nuclear spins is the main dephasing mechanism.

Small magnetic fields (~10 mT) effectively suppress hyperfine-induced dephasing.

Abstract

We have measured the carrier spin dynamics in p-doped InAs/GaAs quantum dots by pump-probe photo-induced circular dichroism and time-resolved photoluminescence experiments. We show that the hole spin dephasing is controlled by the hyperfine interaction between hole and nuclear spins. In the absence of external magnetic field, we find a characteristic hole spin dephasing time of 15 ns, in close agreement with our calculations based on dipole-dipole coupling between the hole and the quantum dot nuclei. Finally we demonstrate that a small external magnetic field, typically 10 mT instead of 200 mT for the case of electrons, quenches the hyperfine hole spin dephasing.