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# Controlled state-to-state atom-exchange reaction in an ultracold atom–dimer mixture

## Abstract

Ultracold molecules offer remarkable opportunities for the study of chemical reactions close to zero temperature. Although significant progress has been achieved in exploring ultracold bimolecular reactions, the investigations are usually limited to measurements of the overall loss rates of the reactants. Detection of the reaction products will improve our understanding of the reaction mechanism and provide a unique opportunity to study the state-to-state reaction dynamics. Here we report on the direct observation of an exoergic atom-exchange reaction in an ultracold atom–dimer mixture. Both the atom and molecule products are observed and the state-to-state reaction rate coefficient is measured. By changing the magnetic field, the reaction can be switched on or off, and the rate coefficient can be controlled. The observed atom-exchange reaction is an effective spin-exchange interaction between the dimer and the atom and may be exploited to study the Kondo effect with ultracold atoms.

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• ### Reaction kinetics of ultracold molecule-molecule collisions

Nature Communications Open Access 07 December 2018

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## Acknowledgements

We would like to thank X.-M. Yang for helpful discussions, and I. Nosske for carefully reading the manuscript. This work was supported by the National Natural Science Foundation of China (under Grant No.11521063, 11274292, 11374284, and 11425417), the National Fundamental Research Program (under Grant No. 2013CB922001 and 2013CB336800), and the Chinese Academy of Sciences.

## Author information

Authors

### Contributions

Y.-A.C., B.Z. and J.-W.P. conceived the experiments. J.R., H.Y., L.L., D.-C.Z. and Y.-X.L. carried out the experiments. J.N. and B.Z. performed the numerical calculations. All authors analysed the data and contributed to the writing of the paper. B.Z. and J.-W.P. supervised the work.

### Corresponding authors

Correspondence to Bo Zhao or Jian-Wei Pan.

## Ethics declarations

### Competing interests

The authors declare no competing financial interests.

## Supplementary information

### Supplementary information

Supplementary information (PDF 378 kb)

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Rui, J., Yang, H., Liu, L. et al. Controlled state-to-state atom-exchange reaction in an ultracold atom–dimer mixture. Nature Phys 13, 699–703 (2017). https://doi.org/10.1038/nphys4095

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• DOI: https://doi.org/10.1038/nphys4095

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