Quantum-tomography of entangled photon pairs by quantum-dot cascade decay

TL;DR

This paper analyzes how cavity effects influence the entanglement quality of photon pairs emitted from quantum dots, highlighting the impact of cavity coupling and detection efficiency on the fidelity of quantum-tomography.

Contribution

It provides a detailed theoretical analysis of the factors affecting entangled photon-pair generation via quantum-dot cascade decay, including cavity-induced emission rate enhancements and competing processes.

Findings

Cavity-induced increase in photon emission rate improves entanglement.

Strong dot-cavity coupling and detection inefficiencies reduce entanglement quality.

Competing processes can diminish the effectiveness of the cascade decay for entanglement generation.

Abstract

We compute the concurrence of the polarization-entangled photon pairs generated by the biexciton cascade decay of a semiconductor quantum dot. We show how a cavity-induced increase of the photon rate emission reduces the detrimental effect of the dot dephasing and of the excitonic fine structure. However, strong dot-cavity couplings and finite detection efficiencies are shown to reduce the relevance of the desired cascade decay with respect to that of competing processes. This affects the merits of the entangled photon-pair source, beyond what estimated by the quantum-tomography.