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  • Letter
  • Open Access

Precision spectroscopy of ultracold Sr286 halo molecules

B. Iritani1, J. Huang1, W. Xu1, G. Sim1, R. Moszynski2, and T. Zelevinsky1,*

  • 1Department of Physics, Columbia University, 538 West 120th Street, New York, New York 10027-5255, USA
  • 2Quantum Chemistry Laboratory, Department of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland

  • *Contact author: tanya.zelevinsky@columbia.edu
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Phys. Rev. Research 8, L032047 – Published 23 September, 2026

DOI: https://doi.org/10.1103/6148-4lbn

Abstract

We demonstrate the creation and field-free precision spectroscopy of ultracold Sr286 molecules in the halo regime, where vibrational binding energies are dominated by long-range interactions. Using one-photon photoassociation with optimized wavefunction overlap, we produce stable samples of halo and neighboring weakly bound molecular states. We measure vibrational splittings of the three least-bound states with sub-100-Hz uncertainty, enabling a high-precision determination of absolute binding energies. These results establish Sr286 halo molecules as a new platform for precision studies of long-range molecular forces, including quantum electrodynamics effects such as Casimir-Polder interactions, and provide a direct basis for isotope-shift spectroscopy sensitive to nanometer-scale mass-dependent forces.

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Phys. Rev. Research 8, L032047– Published 23 September, 2026
  • Received 9 January 2026
  • Accepted 6 August 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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