Quantum-State Controlled Penning Ionization Reactions between Ultracold Alkali and Metastable Helium Atoms

Abstract

In an ultracold, optically trapped mixture of ${}^{87}$Rb and metastable triplet ${}^4$He atoms we have studied trap loss for different spin-state combinations, for which interspecies Penning ionization is the main two-body loss process. We observe long trapping lifetimes for the purely quartet spin-state combination, indicating strong suppression of Penning ionization loss by at least two orders of magnitude. For the other spin-mixtures we observe short lifetimes that depend linearly on the doublet character of the entrance channel. We compare the extracted loss rate coefficient with recent predictions of multichannel quantum-defect theory for reactive collisions involving a strong exothermic loss channel and find near-universal loss for doublet scattering. Our work demonstrates control of reactive collisions by internal atomic state preparation.

5 pages, 5 figures + Supplemental Materials

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Cited by in corpus (7)

• Quantum spin state selectivity and magnetic tuning of ultracold chemical reactions of triplet alkali-metal dimers with alkali-metal atoms
• Strong angular-momentum mixing in ultracold atom-ion excitation-exchange
• Penning collisions between supersonically expanded metastable helium atoms and laser-cooled lithium atoms
• Imaging recoil ions from optical collisions between ultracold, metastable neon isotopes
• An ultracold, optically trapped mixture of {87}Rb and metastable {4}He atoms
• Suppression of Penning ionization by orbital angular momentum conservation
• Spin-state-controlled chemi-ionization reactions between metastable helium atoms and ground-state lithium atoms