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arXiv · 2507.12936

Magnetic Feshbach resonances in Ba$^+$+Li collisions due to strong spin-orbit coupling

Masato Morita·Joachim Siemund·Wei Wu·Daniel von Schoenfeld·Jonathan Grieshaber·Agata Wojciechowska·Krzysztof Jachymski·Thomas Walker·Fabian Thielemann·Tobias Schaetz·Michał Tomza
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Abstract

We report a pronounced dependence of magnetic Feshbach resonance spectra on the initial hyperfine-Zeeman state of Li in ultracold $^{138}$Ba$^+$+$^6$Li collisions. The measured number and distribution of resonances differ significantly between the two lowest states despite their similar electron spin character. We address this puzzle by developing a comprehensive yet generic computational model calibrated against key statistical features in the experimental spectrum. We confirm that strong spin-orbit coupling induces essential changes in the distribution of resonances, leading to an increase in the number of resolvable resonances. Our model reproduces the statistics of the spectrum with the lowest Li state but struggles with the second-lowest state, where a significantly smaller number of resonances is experimentally observed.

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Masato Morita, Joachim Siemund, Wei Wu, Daniel von Schoenfeld, Jonathan Grieshaber, Agata Wojciechowska, Krzysztof Jachymski, Thomas Walker, Fabian Thielemann, Tobias Schaetz, Michał Tomza. 2025-07-17. Magnetic Feshbach resonances in Ba$^+$+Li collisions due to strong spin-orbit coupling. https://arxiv.org/abs/2507.12936

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