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Polarization dependence of spin-electric transitions in molecular exchange qubits

Filippo Troiani ^*

Athanassios K. Boudalis

Centro S3, CNR-Istituto di Nanoscienze, I-41125 Modena, Italy

Institut de Chimie (UMR7177 CNRS-Université de Strasbourg), CS-90032, F-67081 Strasbourg Cedex, France

^*Contact author: filippo.troiani@nano.cnr.it

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Phys. Rev. B 113, 075409 – Published 6 February, 2026

DOI: https://doi.org/10.1103/nfxt-sfg2

Abstract

Quasi-optical experiments are emerging as a powerful technique to probe magnetic transitions in molecular spin systems. However, the simultaneous presence of the electric- and magnetic-dipole induced transitions poses the challenge of discriminating between these two contributions. In addition, the identification of the spin-electron transitions can hardly rely on the peak intensity because of the current uncertainties on the value of the spin-electric coupling in most molecular compounds. Here, we compute the polarizations required for electric- and magnetic-dipole induced transitions through spin-Hamiltonian models of molecular spin triangles. We show that the polarization allows a clear discrimination between the two kinds of transitions. In addition, it allows one to identify the physical origin of the zero-field splitting in the ground multiplet, a debated issue with significant implications on the coherence properties of the spin qubit implemented in molecular spin triangles.

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Phys. Rev. B 113, 075409– Published 6 February, 2026

Vol. 113, Iss. 7 — 15 February 2026

Received 6 October 2025
Revised 15 December 2025
Accepted 12 January 2026

DOI: https://doi.org/10.1103/nfxt-sfg2

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.

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Polarization dependence of spin-electric transitions in molecular exchange qubits

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