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Optical Excitation and Stabilization of Ultracold Field-Linked Tetratomic Molecules

Bijit Mukherjee* and Michał Tomza†

  • *Contact author: bijit.mukherjee@fuw.edu.pl
  • †Contact author: michal.tomza@fuw.edu.pl
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Phys. Rev. Lett. 136, 013401 – Published 6 January, 2026

DOI: https://doi.org/10.1103/j17b-x1x7

Abstract

We propose a coherent optical population transfer of weakly bound field-linked (FL) tetratomic molecules (tetramers) to deeper FL bound states using stimulated Raman adiabatic passage. We consider static-electric-field shielded polar alkali-metal diatomic molecules and corresponding FL tetramers in their X1Σ++X1Σ+ ground electronic state. We show that the excited metastable X1Σ++b3Π electronic manifold supports FL tetramers in a broader range of electric fields with collisional shielding extended to zero field. We calculate the Franck-Condon factors between the ground and excited FL tetramers and show that they are highly tunable with the electric field. We also predict photoassociation of ground-state shielded molecules to the excited FL states in free-bound optical transitions. We propose proof-of-principle experiments to implement stimulated Raman adiabatic passage and photoassociation using FL tetramers, paving the way for the formation of deeply bound ultracold polyatomic molecules.

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Phys. Rev. Lett. 136, 013401– Published 6 January, 2026
  • Received 13 June 2025
  • Revised 20 November 2025
  • Accepted 22 December 2025
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