Bell state measurements in quantum optics: a review of recent progress and open challenges

Year: 2026

Authors: Bianchi L., Marconi C., Bacco D.

Autors Affiliation: Univ Florence, Dept Phys & Astron, I-50019 Florence, Italy; CNR, Ist Nazl Ott, Largo Enr Fermi 6, I-50125 Florence, Italy.

Abstract: Bell state measurements, which project bipartite states onto the maximally entangled Bell basis, are central to a wide range of quantum information processing tasks, including quantum teleportation, entanglement swapping, and fusion-gate quantum computation. In photonic platforms, where information is encoded in optical degrees of freedom, the realization of efficient Bell state measurements is particularly challenging, especially when constrained to linear optical elements. In this review, we provide a comprehensive examination of existing proposals for the implementation of Bell state measurements, highlighting their fundamental limitations and the strategies developed to overcome them. Moreover, we survey recent advances and discuss open challenges, with a particular focus on Bell state measurements for high-dimensional systems, an area of growing interest due to its relevance for quantum repeaters and scalable quantum networks.

Journal/Review: QUANTUM SCIENCE AND TECHNOLOGY

Volume: 11 (2)      Pages from: 23001-1  to: 23001-23

More Information: LB thanks Francesco Salusti and Giorgio De Pascalis for fruitful discussions. LB and DB acknowledge support from the European Union ERC StG, QOMUNE, 101077917. CM acknowledges support from the European Union-NextGeneration EU, Integrated infrastructure initiative in Photonic and Quantum Sciences – I-PHOQS [IR0000016, ID D2B8D520, CUP B53C22001750006].
KeyWords: quantum network; quantum communication; multidimensional quantum states; Bell state measurement
DOI: 10.1088/2058-9565/ae609e