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Near degeneracies between opposite parity states in the heavy DyAg molecule

S. Kotochigova1,*, J. Kłos1,2, and E. Tiesinga2

  • *Contact author: svetlana.kotochigova@temple.edu
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Phys. Rev. A 114, 033314 – Published 9 September, 2026

DOI: https://doi.org/10.1103/9jc6-ntbz

Abstract

We theoretically investigate the rare-earth Dy163Ag107 molecule as a quantum sensor to amplify weak symmetry-breaking interactions not included in the standard model of physics. We focus on parity-breaking interactions from the octupole-deformed Dy163 nucleus. To characterize key properties for this molecule, we have performed relativistic electronic configuration-interaction and rovibrational coupled-channels calculations. We show that near the equilibrium geometry, the bond is ionic with the Dy atom losing an electron from its open, submerged 4f electron shell to Ag. In fact, the Dy163Ag107 ground-state configuration corresponds to a Dy ion with a large electronic angular momentum of jDy+=15ℏ/2 and a spinless silver ion. Here, ℏ is the reduced Planck constant. We also observe that the crystal-field splittings among states with projections Ω of jDy+ along the internuclear axis are on the order of the vibrational spacings in Dy163Ag107 and orders of magnitude larger than the rotational spacings, Coriolis-induced Ω-type doubling, the hyperfine interactions between the spins of the electrons and the Dy163 nucleus, and Zeeman interactions when an external magnetic field is applied. The spin-stretched state with |Ω|=jDy+ is the ground state. The splittings between the Ω-doublets, a pair of states with opposite parity, dramatically depend on Ω. We predict values on the order of h×10GHz, h×10MHz, and h×1kHz for Ω=ℏ/2, 3ℏ/2, and 5ℏ/2, respectively, with Planck constant h. For larger values of Ω, the splittings decrease by additional orders of magnitude. Parity violations and thus the mixing of the Ω-doublets can be achieved by simply applying external electric fields or by interactions induced by the octupole-deformed Dy163 nucleus through coupling of its nuclear spin to molecular rotation. The actual energy shifts from the latter contribution are not known as they originate from nuclear forces.

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Phys. Rev. A 114, 033314– Published 9 September, 2026
  • Received 22 April 2026
  • Accepted 31 July 2026
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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.

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