Quantum Dots as Solid-State Sources of Entangled Photon Pairs

TL;DR

Quantum dots are promising solid-state sources for entangled photon pairs, with recent advances improving their brightness, coherence, and fidelity, crucial for scalable quantum technologies.

Contribution

This review highlights recent progress in QD-based entangled photon sources, emphasizing new paradigms, nanophotonic enhancements, and challenges for practical deployment.

Findings

Advances in nanophotonic architectures improve source performance.

Transition from biexciton-exciton cascade to spontaneous two-photon emission.

Identification of key challenges for large-scale quantum applications.

Abstract

Semiconductor quantum dots (QDs) have emerged as a premier solid-state platform for the deterministic generation of nonclassical light, offering a compelling pathway toward scalable quantum photonic systems. While single-photon emission from QDs has reached a high level of maturity, the realization of high-fidelity entangled photon-pair sources remains an active and rapidly evolving frontier. In this review, we survey the recent progress in QD-based entangled photon sources, highlighting the conceptual evolution from the established biexciton-exciton cascade to the emerging paradigm of spontaneous two-photon emission. We further examine how advances in nanophotonic architectures and coherent control strategies are redefining fundamental performance limits, enabling concurrent improvements in source brightness, coherence, and entanglement fidelity. Finally, we discuss the key physical and technological challenges that must be addressed to bridge the gap between laboratory demonstrations and large-scale deployment. We conclude by outlining the future opportunities for integrating QD-based entangled photon sources into practical quantum communication, computation, and sensing platforms.