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Slowing YbF molecules using radiation pressure

M. Athanasakis-Kaklamanakis*, G. Peng*, S. Li, H. Septien-Gonzalez, C. Debavelaere, A. D. White, S. Popa, J. Lim, B. E. Sauer et al.

M. R. Tarbutt†

  • *These authors contributed equally to this work.
  • †Contact author: m.tarbutt@imperial.ac.uk
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Phys. Rev. Research 7, 043235 – Published 1 December, 2025

DOI: https://doi.org/10.1103/2vdb-c1f5

Abstract

We report radiation pressure slowing of YbF molecules to low velocity. In YbF, laser slowing is hindered by leaks out of the optical cycle attributed to low-lying metastable electronic states arising from inner-shell excitation. We bring this population back into the optical cycle once it has decayed to the electronic ground state using microwaves to couple the relevant rotational levels. We measure the scattering rate and closure of the optical cycle as repumps are added, and study the destabilization of dark states by a magnetic field and by polarization modulation, finding that both are helpful for maximizing the scattering rate. Starting from a beam with a mean speed of 80 m/s, and using frequency-broadened slowing light, we reduce the mean speed of the beam and produce a substantial flux in the low-velocity tail of the distribution. Slowing increases the fraction of molecules below 40 m/s from 0.4(1)% to 7.0(2)%, and the fraction below 30 m/s from zero to 3.2(1)%. The establishment of a nearly closed optical cycle and the production of molecules at low velocity are important steps toward trapping YbF molecules for future measurements of the electron's electric dipole moment.

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Phys. Rev. Research 7, 043235– Published 1 December, 2025
  • Received 22 August 2025
  • Accepted 10 November 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.

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