Temperature dependence of hole spin coherence in (In,Ga)As quantum dots measured by mode-locking and echo techniques

TL;DR

This study investigates how temperature affects hole spin coherence in (In,Ga)As quantum dots, revealing a sharp decline in coherence times above 8 K likely due to spin-orbit interactions rather than hyperfine effects.

Contribution

It provides new insights into the temperature-dependent decoherence mechanisms of hole spins, emphasizing the role of spin-orbit interactions in quantum dots.

Findings

Coherence times are about 1 microsecond below 8 K.

Rapid decrease in coherence times occurs between 8 K and 18 K.

Hyperfine interactions are too weak to explain decoherence at higher temperatures.

Abstract

The temperature dependence of the coherence time of hole spins confined in self-assembled (In,Ga)As/GaAs quantum dots is studied by spin mode-locking and spin echo techniques. Coherence times limited to about a \mu s are measured for temperatures below 8 K. For higher temperatures a fast drop occurs down to a few ns over a 10 K range. The hole-nuclear hyperfine interaction appears too weak to account for these limitations. We suggest that spin-orbit related interactions are the decisive sources for hole spin decoherence.