Spin noise of electrons and holes in (In,Ga)As quantum dots: experiment and theory

TL;DR

This study investigates electron and hole spin noise in (In,Ga)As quantum dots through experiments and models, revealing hyperfine interactions, spin precession, and magnetic field effects on spin coherence times.

Contribution

It provides a combined experimental and theoretical analysis of spin fluctuations, highlighting the impact of magnetic fields on spin decoherence and hyperfine interactions in quantum dots.

Findings

Electron spin fluctuations precess around nuclear Overhauser fields.

Longer spin decoherence times for electrons and holes than previously known.

Magnetic fields significantly extend spin lifetimes by decoupling spins from nuclear spins.

Abstract

The spin fluctuations of electron and hole doped self-assembled quantum dot ensembles are measured optically in the low-intensity limit of a probe laser in absence and presence of longitudinal or transverse static magnetic fields. The experimental results are modeled by two complementary approaches based either on semiclassical or quantum mechanical descriptions. This allows us to characterize the hyperfine interaction of electron and hole spins with the surrounding bath of nuclei on time scales covering several orders of magnitude. Our results demonstrate (i) the intrinsic precession of the electron spin fluctuations around the effective nuclear Overhauser field caused by the host lattice nuclear spins, (ii) the comparably long time scales for electron and hole spin decoherence, as well as (iii) the dramatic enhancement of the spin lifetimes induced by a longitudinal magnetic field due to the decoupling of nuclear and charge carrier spins.