Testing single-photon entanglement using self-referential measurements
- Author(s)
- Daniel Kun, Teodor Strömberg, Borivoje Dakić, Philip Walther, Lee A. Rozema
- Abstract
Entanglement does not always require one particle per party. It was predicted some 30 years ago that a single photon traversing a beam splitter could violate a Bell inequality. Although initially debated, single-photon nonlocality was eventually demonstrated via homodyne measurements. Here, we present an alternate realization that avoids the complexity of homodyne measurements and potential loopholes in their implementation. We violate a Bell inequality by performing joint measurements on two copies of the same single-photon entangled state, where one photon acts as a phase reference for the other, making it self-referential. We observe CHSH parameters of 2.71 ± 0.09 and 2.23 ± 0.07, depending on the joint measurements implemented. This offers a perspective on single-photon nonlocality and a more accessible experimental route, potentially applicable to general mode-entangled states in diverse platforms.
- Organisation(s)
- Quantum Optics, Quantum Nanophysics and Quantum Information
- External organisation(s)
- IST Austria - Institute of Science and Technology, Österreichische Akademie der Wissenschaften (ÖAW)
- Journal
- Optica
- Volume
- 13
- Pages
- 745-751
- No. of pages
- 7
- ISSN
- 2334-2536
- DOI
- https://doi.org/10.48550/arXiv.2511.21819
- Publication date
- 04-2026
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 103026 Quantum optics, 103025 Quantum mechanics
- ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials, Atomic and Molecular Physics, and Optics
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/4b6aa880-f7b5-4dc0-a75e-e6ed4c836997