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Postselection free time-bin entanglement on a thin-film lithium niobate photonic chip

Marcello Bacchi1,*, Andrea Bernardi2,3,*,†, Marco Clementi1, Sara Congia1,4, Francesco Garrisi3, Andrea Martellosio3, Marco Passoni3, Alexander Wrobel3, Federico Andrea Sabattoli3 et al.

Matteo Galli1 and Daniele Bajoni2

  • *These authors contributed equally to this work.
  • †Contact author: andrea.bernardi01@universitadipavia.it
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Phys. Rev. Applied 25, 064045 – Published 11 June, 2026

DOI: https://doi.org/10.1103/1sjz-tw85

Abstract

Time-bin entanglement is a commonly used form of entanglement for quantum communication protocols over fiber networks, due to the natural resilience of this encoding scheme to thermal phase fluctuations and to birefringence in optical fibers. Projective measurements on some bases in the time-bin encoding need, however, postselection in the time domain of the measured events, introducing a loophole in Bell tests and requiring high temporal resolution. In this work, we demonstrate chip-integrated receivers for time-bin entanglement certification, including a high-speed optical switch to remove the temporal postselection loophole. The receivers are realized using thin-film lithium niobate and operate at a switching frequency of 5 GHz. We demonstrate a Bell inequality violation by more than 24 standard deviations without the need for time resolution at the time-bin separation level.

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Phys. Rev. Applied 25, 064045– Published 11 June, 2026
  • Received 24 December 2025
  • Revised 23 March 2026
  • Accepted 12 May 2026
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