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Molecular spin qudits to test generalized Bell inequalities

Silvia Macedonio1,2, Luca Lepori1,2, Alessandro Chiesa1,2,3, Simone Chicco1, Laura Bersani1, Marcos Rubin-Osanz1, Lukas Bradley Woodcock4, Athanasios Mavromagoulos4, Giuseppe Allodi1 et al.

Elena Garlatti1,2,3, Stergios Piligkos4, Augusto Smerzi5, and Stefano Carretta1,2,3,*

  • *Contact author: stefano.carretta@unipr.it
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Phys. Rev. Research 8, 013138 – Published 9 February, 2026

DOI: https://doi.org/10.1103/sn37-b9rr

Abstract

We show that molecular nanomagnets provide an ideal platform to investigate entanglement in qubit-qudit and qudit-qudit pairs. A prototypical example is Yb173 (trensal), embedding an electronic spin qubit coupled to a nuclear spin qudit. We demonstrate violation of generalized Bell inequalities on this molecule by developing an optimized pulse sequence and by performing realistic numerical simulations using experimentally measured Hamiltonian parameters and coherence times. We find that the inequalities are safely violated in a wide range of parameters, proving the robustness of entanglement in the investigated system. Furthermore, we propose a scheme to study qudit-qudit entanglement on a molecular spin trimer, in which two spins 3/2 are linked via an interposed switch to turn on and off their mutual interaction.

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Phys. Rev. Research 8, 013138– Published 9 February, 2026
  • Received 8 September 2025
  • Accepted 5 January 2026
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