Wavevector-resolved polarization entanglement from radiative cascades
The generation of entangled photons from radiative cascades has enabled milestone experiments in quantum information science with several applications in photonic quantum technologies. Significant efforts are being devoted to pushing the performances of near-deterministic entangled-photon sources based on single quantum emitters often embedded in photonic cavities, so to boost the flux of photon pairs. The general postulate is that the emitter generates photons in a nearly maximally entangled state of polarization, ready for application purposes. Here, we demonstrate that this assumption is unjustified. We show that in radiative cascades there exists an interplay between photon polarization and emission wavevector, which can be further amplified by embedding the emitters in micro-cavities. We discuss how the polarization entanglement of photon pairs from a biexciton-exciton cascade in quantum dots strongly depends on their propagation wavevector and we even observe entanglement vanishing for large emission angles. Our experimental results, backed by theoretical modeling, yield a brand-new understanding of cascaded emission for various quantum emitters. In addition, our model provides quantitative guidelines for designing optical microcavities that retain both a high degree of entanglement and collection efficiency, moving the community one step further towards an ideal source of entangled photons for quantum technologies.
Authors
- Armando Rastelli (ORCID: https://orcid.org/0000-0002-1343-4962)
- Saimon F. Covre da Silva
- Francesco Basso Basset (ORCID: https://orcid.org/0000-0002-2148-0010)
- Sandra Stroj (ORCID: https://orcid.org/0000-0001-6387-4248)
- Sven Höfling (ORCID: https://orcid.org/0000-0003-0034-4682)
- Rinaldo Trotta (ORCID: https://orcid.org/0000-0002-9515-6790)
- Mattia Beccaceci (ORCID: https://orcid.org/0009-0002-0988-5389)
- Valentina Villari (ORCID: https://orcid.org/0000-0002-7907-842X)
- Alessandro Laneve (ORCID: https://orcid.org/0000-0002-0416-5131)
- Quirin Buchinger (ORCID: https://orcid.org/0000-0002-2114-2628)
- Tobias M. Krieger (ORCID: https://orcid.org/0000-0003-1245-9866)
- Michele B. Rota (ORCID: https://orcid.org/0000-0003-3933-6997)
- Andreas Pfenning (ORCID: https://orcid.org/0000-0002-7390-5041)
- Yorick Reum (ORCID: https://orcid.org/0009-0009-2635-8231)
- Thomas Oberleitner (ORCID: https://orcid.org/0009-0002-0500-2761)
- R. Prasad (ORCID: https://orcid.org/0000-0002-4009-8167)
- Tobias Huber (ORCID: https://orcid.org/0000-0002-5788-8501)
Institutions
- Johannes Kepler University of Linz (AT)
- Universidade Estadual de Campinas (UNICAMP) (BR)
- University of Würzburg (DE)
- Vorarlberg University of Applied Sciences (AT)
- Sapienza University of Rome (IT)
- Politecnico di Milano (IT)
Publication Details
- Journal
- Nature Communications
- Published
- 2025-07-05
- DOI
- https://doi.org/10.1038/s41467-025-61460-3
- Citations
- 2
- Primary Topic
- Quantum Information and Cryptography
- Type
- article
- Field-Weighted Citation Impact
- 4.96
Funders
- European Commission
- Fundação de Amparo à Pesquisa do Estado de São Paulo
- Bundesministerium für Bildung und Forschung
- Austrian Science Fund
- QuantERA
- Ministero dell'Università e della Ricerca
- Horizon 2020 Framework Programme
- HORIZON EUROPE Framework Programme