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  • Open Access

Testing entanglement between free-traveling electron-positron pairs

Leyun Gao*, Alim Ruzi†, Qite Li‡, Chen Zhou§, and Qiang Li∥

  • State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing, 100871, People’s Republic of China

  • *Contact author: seeson@pku.edu.cn
  • †Contact author: alim.ruzi@pku.edu.cn
  • ‡Contact author: liqt@pku.edu.cn
  • §Contact author: czhouphy@pku.edu.cn
  • ∥Contact author: qliphy0@pku.edu.cn
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Phys. Rev. D 111, 116018 – Published 18 June, 2025

DOI: https://doi.org/10.1103/m9z9-1jpd

Abstract

Quantum entanglement is a cornerstone of quantum mechanics. While the entanglement of confined electron pairs has been established early on, the entanglement of free-traveling electron pairs, particularly at high energies, remains largely unexplored due to the substantial challenges involved in measuring the spins of free-traveling electrons. In this study, we investigate the entanglement and the Bell inequality violation of free-traveling electron-positron pairs generated in a fixed-target experiment. This experimental setup facilitates the creation of a controllable source of entangled electron-positron pairs, where entangled events are produced in specific phase spaces. Based on this source and the prior knowledge of the entangled state, we demonstrate the feasibility of measuring the polarization correlations of the entangled e+e− pairs through their individual secondary scatterings off two separate additional targets.

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Information

Phys. Rev. D 111, 116018– Published 18 June, 2025
  • Received 23 February 2025
  • Accepted 21 May 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.

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