Resonant energy transfer in low-temperature collisions of Rydberg atoms with polar polyatomic molecules

The resonant exchange of energy between the nuclear degrees of freedom of polar polyatomic molecules, and the electron in a Rydberg atom can be studied at temperatures below 100 mK in pulsed supersonic beams [1,2]. These energy transfer processes can occur as a result of resonant electric dipole-dipole interactions at long-range – when the molecule is outside the charge distribution of the Rydberg electron – or at shorter range when the molecule is inside the charge distribution of, and interacts directly with the Rydberg electron. In this talk, I will describe a series of intrabeam collision experiments, in which we have studied resonant rotational and vibrational energy transfer from polar ground-state ammonia molecules (electric dipole moment 1.47 D) to Rydberg helium atoms (electric dipole transition moments ~3000 D). At long-range, electric dipole-dipole interactions between these systems can be tuned into resonance using dc electric fields of 1 — 10 V/cm to induce Stark shifts of the Rydberg states, and enable resonant energy transfer [2,3]. If a molecule enters inside the Rydberg-electron charge distribution, the symmetry of the Rydberg atom is broken and, as I will show, energy transfer between states that would not full-fill the selection rules associated with purely electric dipole-dipole interactions at long-range can occur [4]. These observations are of interest, e.g., in investigations of ultralong-range bound states of Rydberg atoms/molecules and polar molecules [5], the implementation of methods for non-destructive detection of polar molecules [6], and applications in quantum simulation and information processing [7,8]. 

[1] C. Amarasinghe and A. G. Suits, J. Phys. Chem. Lett. 8, 5153 (2017)

[2] K. Gawlas and S. D. Hogan, J. Phys. Chem. Lett. 11, 83 (2020)

[3] J. Zou and S. D. Hogan, Phys. Rev. A 106, 043111 (2022)

[4] J. Zou, et al. arXiv:2509.21582 (2025)

[5] R. González-Férez, et al. Phys. Rev. Lett. 126, 043401 (2021)

[6] M. Zeppenfeld, EuroPhys. Lett. 118, 13002 (2017)

[7] K. Wang, et al. PRX Quantum 3, 030339 (2022)

[8] C. Zhang and M. R. Tarbutt, PRX Quantum 3, 030340 (2022)