Hyperfine-interaction limits polarization entanglement of photons from semiconductor quantum dots

TL;DR

This paper investigates how hyperfine interactions with nuclear spins limit the polarization entanglement of photon pairs emitted from semiconductor quantum dots, providing a quantitative upper bound on entanglement fidelity.

Contribution

It offers a quantitative analysis of hyperfine effects on entanglement in quantum dots and proposes strategies to mitigate spin-noise impacts.

Findings

Hyperfine interactions set an upper limit on entanglement fidelity.

Spin-noise is identified as the main limiting factor.

Results align with existing literature and suggest mitigation routes.

Abstract

Excitons in quantum dots are excellent sources of polarization-entangled photon pairs, but a quantitative understanding of their interaction with the nuclear spin bath is still missing. Here we investigate the role of hyperfine energy shifts using experimentally accessible parameters and derive an upper limit to the achievable entanglement fidelity. Our results are consistent with all available literature, indicate that spin-noise is often the dominant process limiting the entanglement in InGaAs quantum dots, and suggest routes to alleviate its effect.