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arXiv:2406.08671 · Physical Review A

Elucidating the roles of collision energy and photon momentum transfer in the formation of ultralong-range Rydberg molecules

C. Wang, Y. Lu, S. K. Kanungo, F. B. Dunning, T. C. Killian, S. Yoshida

Published Sep 6, 2024• 4 citations
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Abstract

Spectroscopic measurements of the rotational distribution of $^{84}\mathrm{Sr}$ and $^{86}\mathrm{Sr}\phantom{\rule{4pt}{0ex}}\phantom{\rule{0.16em}{0ex}}5sns{\phantom{\rule{0.16em}{0ex}}}^{1}{S}_{0}$ ultralong-range Rydberg molecular dimers created via photoassociation in a cold gas are reported. The dimers are produced by two-photon excitation via the $5s5p$ $^{1}P_{1}$ intermediate state. The use of singlet states permits detailed study of the roles that the initial atom-atom interaction, photon momentum transfer during Rydberg excitation, and sample temperature play in determining the spectral line shape and final dimer rotational distribution. The results are in good agreement with the predictions of a model that includes these effects. The present work further highlights the sensitivity of ultralong-range Rydberg molecule formation to the state of the initial cold gas.

DOI
10.1103/physreva.110.032803

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Anomalies in the rotational structure of 86Sr^{86}\mathrm{Sr}86Sr 3S1^{3}S_{1}3S1​ dimer ultralong-range Rydberg molecules created in a cold strontium gas by two-photon excitation via the intermediate 5s5p5s5p5s5p 3P1^{3}P_{1}3P1​ state are reported. Measurements reveal that the distribution of product rotational states is sensitive to intermediate state detuning. Comparative studies using 84Sr^{84}\mathrm{Sr}84Sr 1S0^{1}S_{0}1S0​ and 3S1^{3}S_{1}3S1​, and 86Sr^{86}\mathrm{Sr}86Sr 1S0^{1}S_{0}1S0​ dimers display no similar behavior, indicating that the observed behavior is peculiar to 86Sr^{86}\mathrm{Sr}86Sr triplet dimers. While we have no definitive hypothesis as to the physical mechanism responsible for this behavior, possible explanations might involve the very different scattering lengths for 84Sr^{84}\mathrm{Sr}84Sr and 86Sr^{86}\mathrm{Sr}86Sr, or the interchange of spin and rotational angular momentum.
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Anomalies in the rotational spectra of 86^{86}86Sr ULRRM dimers
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We report the creation of ultra-long-range Sr2{\mathrm{Sr}}_{2}Sr2​ molecules comprising one ground-state 5s25{s}^{2}5s2 1S0{}^{1}{S}_{0}1S0​ atom and one atom in a 5sns5sns5sns 3S1{}^{3}{S}_{1}3S1​ Rydberg state for nnn ranging from 29 to 36. Molecules are created in a trapped ultracold atomic gas using two-photon excitation near resonant with the 5s5p5s5p5s5p 3P1{}^{3}{P}_{1}3P1​ intermediate state, and their formation is detected through ground-state atom loss from the trap. The observed molecular binding energies are reproduced with the aid of first-order perturbation theory that utilizes a Fermi pseudopotential with effective sss-wave and ppp-wave scattering lengths to describe the interaction between an excited Rydberg electron and a ground-state Sr atom.