Observation of heavy-hole hyperfine interaction in quantum dots

TL;DR

This paper measures the hyperfine interaction of heavy-holes with nuclear spins in quantum dots, revealing a small negative ratio to electron hyperfine interaction, which impacts quantum information processing.

Contribution

It introduces a novel spectroscopic technique to measure heavy-hole hyperfine interactions and provides the first quantitative analysis of their strength and sign in quantum dots.

Findings

Heavy-hole hyperfine interaction ratio is -0.09 ± 0.02.

The technique enables precise measurement of nuclear-spin mediated effects.

Results are relevant for quantum dot spin qubit decoherence understanding.

Abstract

We measure the strength and the sign of hyperfine interaction of a heavy-hole with nuclear spins in single self-assembled quantum dots. Our experiments utilize the locking of a quantum dot resonance to an incident laser frequency to generate nuclear spin polarization. By monitoring the resulting Overhauser shift of optical transitions that are split either by electron or exciton Zeeman energy with respect to the locked transition using resonance fluorescence, we find that the ratio of the heavy-hole and electron hyperfine interactions is -0.09 +/- 0.02 in two QDs. Since hyperfine interactions constitute the principal decoherence source for spin qubits, we expect our results to be important for efforts aimed at using heavy-hole spins in solid-state quantum information processing. The novel spectroscopic technique we develop also brings new insights to the nuclear-spin mediated locking mechanism in quantum dots.