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State-to-state chemistry for three-body recombination in an ultracold rubidium gas

TitleState-to-state chemistry for three-body recombination in an ultracold rubidium gas
Publication TypeJournal Article
Year of Publication2017
AuthorsJ. Wolf, M. Deiß, A. Krükow, E. Tiemann, B. P. Ruzic, Y. Wang, J. P. D’Incao, P. S. Julienne, and J. Hecker Denschlag

Crossed molecular beams have provided decades’ worth of knowledge into how quantum mechanics governs chemical reactivity. Nonetheless, the technique is generally limited to the collision of two partners. Wolf et al. report on a three-body process with full quantum state resolution. By cooling rubidium atoms to ultralow temperatures in an optical trap, they were able to observe dimer formation, stabilized by collision with a third atom, and extract the precise dependence of product states on the initial states of the atoms involved.Science, this issue p. 921Experimental investigation of chemical reactions with full quantum state resolution for all reactants and products has been a long-term challenge. Here we prepare an ultracold few-body quantum state of reactants and demonstrate state-to-state chemistry for the recombination of three spin-polarized ultracold rubidium (Rb) atoms to form a weakly bound Rb2 molecule. The measured product distribution covers about 90% of the final products, and we are able to discriminate between product states with a level splitting as small as 20 megahertz multiplied by Planck’s constant. Furthermore, we formulate propensity rules for the distribution of products, and we develop a theoretical model that predicts many of our experimental observations. The scheme can readily be adapted to other species and opens a door to detailed investigations of inelastic or reactive processes.