2025/09/03 by Kim, Ho June, Schmid, Fabian, Holzapfel, David +1
#Atomic Physics (physics.atom-ph) #FOS: Physical sciences #Quantum Physics (quant-ph)
paper · doi:10.48550/arxiv.2509.03625
We report on efficient rovibrational state-selective loading of single H2+ molecular ions into a cryogenic linear Paul trap using (2+1) resonance-enhanced multi-photon ionization (REMPI). The H2+ ions are created by resonant two-photon excitation of H2 molecules from the X 1Σg+ state to the E,F 1Σg+ state, followed by non-resonant one-photon ionization. The H2+ ions are produced from residual gas and sympathetically cooled by a co-trapped, laser-cooled 9Be+ ion. By tuning the wavelength of the REMPI laser, we observe the loading of single H2+ ions via the (ν' = 0, L' = 0, 1, 2, 3) rovibrational levels of the E,F 1Σg+ intermediate state. We measure the success probability for the production of H2+ in the (ν+ = 0, L+ = 1) state via the (ν' = 0, L' = 1) level to be 85(6)% by quantum logic spectroscopy (QLS) of the hyperfine structure of this rovibrational state. Furthermore, we load an H2+ ion via the (ν' = 0, L' = 2) level and confirm its rovibrational state to be (ν+ = 0, L+ = 2) by QLS. We perform QLS probes on the ion over 19 h and observe no decay of the rotationally excited state. Our work demonstrates an efficient state-selective loading mechanism for single-ion, high-precision spectroscopy of hydrogen molecular ions.