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1. Effect of an applied magnetic field on ${}^{84}\mathrm{Sr} n^1{D}_2$ ultralong-range Rydberg dimers

   https://doi.org/10.1103/6bj1-1ywm  

   Yoshida, S; Wang, C; Li, A; Kanungo, S K; Killian, T C; Dunning, F B (August 2026, Physical Review A)

   Photoassociation of $5snd {}^1{D}_2-5s^2 {}^1{S}_0$ ultralong-range Rydberg dimers from an ultracold ${}^{84}\mathrm{Sr}$ atomic gas in a magnetic field is studied. In the absence of magnetic fields, the electronic wave function is aligned along the rotating molecular axis through electron-atom scattering. With increasing magnetic field strength, the symmetry axis of the electron wave function becomes determined by the applied field. While the ground-state atom has no spin or net charge to interact directly with the magnetic field, the dimer wave function in the limit of strong magnetic field becomes aligned along the applied field. Photoassociation spectra show that with increasing field, an increasing number of rovibrational states are excited, indicating strong coupling between rotational states within the Rydberg dimer. 

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2. Photoassociation of ${}^{84}\mathrm{Sr}$ $n{}^1{D}_2$ ultralong-range Rydberg dimers

   https://doi.org/10.1103/ppv2-mlfd  

   Wang, C; Li, A; Kanungo, S K; Killian, T C; Dunning, F B; Yoshida, S (May 2026, Physical Review A)

   Measurements of the production of $5snd{}^1{D}_2–5s^2{}^1{S}_0$ ultralong-range Rydberg dimers through photoassocation in an ultracold ${}^{84}\mathrm{Sr}$ atomic gas are reported. The molecular potential associated with the Rydberg $D$ state is anisotropic and the molecular states are characterized by the vibrational quantum number $\nu$ and the total angular momentum $\vec{K}=\vec{L}+\vec{N}$ , where $\vec{L}$ and $\vec{N}$ are the electronic orbital angular momentum and rotational angular momentum, respectively. The measured molecular binding energies agree reasonably well with theoretical predictions. Additionally, the electron-atom scattering leads to broader line shapes in the photoassociation spectrum than might be expected simply from the angular momentum of the initial colliding cold-atom pairs. 

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3. Observation of Spin-Singlet Butterfly Rydberg Molecules in an Ultracold Atomic Rb Gas

   https://doi.org/10.1103/q5r1-whjr  

   Exner, Markus; Srikumar, Rohan; Blättner, Richard; Schmelcher, Peter; Sadeghpour, H R; Eiles, Matthew T; Ott, Herwig (June 2026, Physical Review Letters)

   We report the observation of spin-singlet ultralong-range Rydberg butterfly molecules consisting of a ground-state atom bound to a Rydberg atom by $P$ -wave scattering of ${}^{87}\mathrm{Rb}$ Rydberg electrons from ${}^{87}\mathrm{Rb}\left(5\mathrm{s}\right)$ atoms. A three-photon excitation scheme enables the photoassociation of these molecules by weakly admixing $\mathrm{Rb}\left(18f_{7/2}\right)$ states. The measured binding energies, kilo-Debye permanent electric dipole moments, and lifetimes are in excellent agreement with theory. Two long-lived vibrational levels, red detuned from the $\mathrm{Rb}\left(18f_{7/2}\right)$ threshold, are observed. This experiment is a foundational step in the production of ultracold anions and heavy Rydberg ion-pair systems. 

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4. Precision measurement of lifetime and branching ratios of the $4f^{13}5d6s^1{[5/2]}_{5/2}$ state in ${\mathrm{Yb}}^{+}$ ions

   https://doi.org/10.1103/mwwc-kng1  

   Duraisamy_Suganthi, Midhuna; So, Visal; Menon, Abhishek; Tomaras, George; Zhuravel, Roman; Pagano, Guido (December 2025, Physical Review Research)

   We report spectroscopic and time-resolved experimental observations to characterize the $\left[\mathrm{Xe}\right]4f^{13}\left({}^{2}F_{5/2}^o\right)5d6s\left({}^{1}D\right){}^1{[5/2]}_{5/2}^o$ state in ${}^{172}\mathrm{Yb}^{+}$  ions. We access this state from the metastable $4f^{14}5d\left({}^{2}D_{3/2,5/2}\right)$ manifold and observe an unexpectedly long lifetime of $\tau =37.9\left(9\right)\mu \mathrm{s}$  that allows visible Rabi oscillations and resolved-sideband spectroscopy. Using a combination of coherent population dynamics, high-fidelity detection and heralded state preparation, and optical pumping methods, we measure the branching ratios to the ${}^{2}D_{3/2}, {}^{2}D_{5/2}$ , and ${}^{2}S_{1/2}$ states to be $0.359\left(2\right)$ , 0.639(2), and $0.0023\left(16\right)$ , respectively. The branching ratio to the $4f^{13}6s^2\left({{}^{2}F}_{7/2}\right)$ is compatible with zero within our experimental resolution. We also report measurements of Landé $g$ -factor of the ${}^1{[5/2]}_{5/2}^o$ state. Further, the branching ratio of the ${}^{2}D_{5/2}$ to ${}^{2}S_{1/2}$ decay in ${}^{172}\mathrm{Yb}^{+}$  was measured to be 0.188(3), improving its relative uncertainty by an order of magnitude. Our measurements provide experimental benchmarks for better understanding the atomic structure of ${\mathrm{Yb}}^{+}$  ions, which still lacks accurate numerical descriptions, and the use of high-lying excited states for partial detection and qubit manipulation in the architecture. 

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5. Properties of Cosmic Deuterons Measured by the Alpha Magnetic Spectrometer

   https://doi.org/10.1103/PhysRevLett.132.261001  

   Aguilar, M; Alpat, B; Ambrosi, G; Anderson, H; Arruda, L; Attig, N; Bagwell, C; Barao, F; Barbanera, M; Barrin, L; et al (June 2024, Physical Review Letters)

   Precision measurements by the Alpha Magnetic Spectrometer (AMS) on the International Space Station of the deuteron ( $D$ ) flux are presented. The measurements are based on $21\times {10}^6$ $D$ nuclei in the rigidity range from 1.9 to 21 GV collected from May 2011 to April 2021. We observe that over the entire rigidity range the $D$ flux exhibits nearly identical time variations with the $p$ , ${}^3\mathrm{He}$ , and ${}^4\mathrm{He}$ fluxes. Above 4.5 GV, the $D/{}^4\mathrm{He}$ flux ratio is time independent and its rigidity dependence is well described by a single power law $\propto R^{\mathrm{\Delta }}$ with ${\mathrm{\Delta }}_{D/{}^4\mathrm{He}}=-0.108\pm 0.005$ . This is in contrast with the ${}^3\mathrm{He}/{}^4\mathrm{He}$ flux ratio for which we find ${\mathrm{\Delta }}_{{}^3\mathrm{He}/{}^4\mathrm{He}}=-0.289\pm 0.003$ . Above $\sim 13\mathrm{GV}$ we find a nearly identical rigidity dependence of the $D$ and $p$ fluxes with a $D/p$ flux ratio of $0.027\pm 0.001$ . These unexpected observations indicate that cosmic deuterons have a sizable primarylike component. With a method independent of cosmic ray propagation, we obtain the primary component of the $D$ flux equal to $9.4\pm 0.5\%$ of the ${}^4\mathrm{He}$ flux and the secondary component of the $D$ flux equal to $58\pm 5\%$ of the ${}^3\mathrm{He}$ flux. Published by the American Physical Society2024 

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