+ Li at ultralow temperatures*

Recent advances in controlling chemical reactivity of ultracold molecules [1,2] have motivated our study of spin-dependent chemical reactions in the presence of external magnetic fields. We present coupled-channel statistical calculations on the ultracold chemical reaction NaLi(a³ Σ⁺) + Na → Na₂ + Li including the Zeeman and hyperfine structure of the reactants. The calculations are based on a set of NaLi-Na potential energy surfaces of quartet and doublet symmetries constructed from the accurate pairwise Na-Li and Na-Na interactions determined from ab initio calculations. We find that the reaction rates are highly sensitive to the initial hyperfine states of the reactants, and can be efficiently controlled by an external magnetic field.

[1] S. Ospelkaus, K.-K. Ni, D. Wang, M. H. G. de Miranda, B. Neyenhuis, G. Quemener, P. S. Julienne, J. L. Bohn, D. S. Jin, and J. Ye, Science 327, 853 (2010).

[2] H. Son, J. J. Park, W. Ketterle, and A. O. Jamison, Nature 580, 197 (2020).