Optical Spin Noise of a Single Hole Spin Localized in an (InGa)As Quantum Dot

TL;DR

This paper demonstrates advanced spin noise spectroscopy capable of detecting and analyzing the spin dynamics of a single heavy hole in a quantum dot, revealing long relaxation times and charge fluctuation effects.

Contribution

It introduces a highly sensitive spin noise spectroscopy technique for single quantum dots and uncovers detailed spin relaxation and charge fluctuation phenomena.

Findings

Longitudinal heavy hole spin relaxation time ≥ 180 μs at 31 mT and 5 K

Inhomogeneous spin noise spectrum due to charge fluctuations

Charge fluctuations influence spin relaxation rate depending on light intensity

Abstract

We advance spin noise spectroscopy to the ultimate limit of single spin detection. This technique enables the measurement of the spin dynamic of a single heavy hole localized in a flat (InGa)As quantum dot. Magnetic field and light intensity dependent studies reveal even at low magnetic fields a strong magnetic field dependence of the longitudinal heavy hole spin relaxation time with an extremely long $T_1$ of $\ge$ 180 $\mu$s at 31 mT and 5 K. The wavelength dependence of the spin noise power discloses for finite light intensities an inhomogeneous single quantum dot spin noise spectrum which is explained by charge fluctuations in the direct neighborhood of the quantum dot. The charge fluctuations are corroborated by the distinct intensity dependence of the effective spin relaxation rate.