Fine-structure changing collisions in 87 Rb upon D 2 excitation in the hyperfine Paschen-Back regime

Higgins, Clare R; Pizzey, Danielle; Hughes, Ifan G

Abstract

We investigate fine structure changing collisions in 87Rb vapour upon D2 excitation in a thermal vapour at 75 ∘C; the atoms are placed in a 0.6 T axial magnetic field in order to gain access to the hyperfine Pashen-Back regime. Following optical excitation on the D2 line, the exothermic transfer 5P 3/2 → 5P 1/2 occurs as a consequence of buffer-gas collisions; the 87Rb subsequently emits a photon on the D1 transition. We employ single-photon counting apparatus to monitor the D1 fluorescence, with an etalon filter to provide high spectral resolution. By studying the D1 fluorescence when the D2 excitation laser is scanned, we see that during the collisional transfer process the mJ′ quantum number of the atom changes, but the nuclear spin projection quantum number, mI′, is conserved. A simple kinematic model incorporating a coefficient of restitution in the collision accounted for the change in velocity distribution of atoms undergoing collisions, and the resulting fluorescence lineshape. The experiment is conducted with a nominally ‘buffer-gas free’ vapour cell; our results show that fine structure changing collisions are important with such media, and point out possible implications for quantum-optics experiments in thermal vapours producing entangled photon pairs with the double ladder configuration, and solar physics magneto-optical filters.

Citation

Higgins, C. R., Pizzey, D., & Hughes, I. G. (2024). Fine-structure changing collisions in 87 Rb upon D 2 excitation in the hyperfine Paschen-Back regime. Journal of Physics B: Atomic, Molecular and Optical Physics, 57(23), Article 235002. https://doi.org/10.1088/1361-6455/ad8ab0

• Journal Article Type: Article
• Acceptance Date: Oct 23, 2024
• Online Publication Date: Nov 13, 2024
• Publication Date: Dec 13, 2024
• Deposit Date: Nov 20, 2024
• Publicly Available Date: Nov 20, 2024
• Journal: Journal of Physics B: Atomic, Molecular and Optical Physics
• Print ISSN: 0953-4075
• Electronic ISSN: 1361-6455
• Publisher: IOP Publishing
• Peer Reviewed: Peer Reviewed
• Volume: 57
• Issue: 23
• Article Number: 235002
• DOI: https://doi.org/10.1088/1361-6455/ad8ab0
• Keywords: thermal vapours, hyperfine Paschen-Back regime, ‘buffer-gas free’, state changing collisions
• Public URL: https://durham-repository.worktribe.com/output/3098699