We experimentally measure and theoretically analyze the three-atom recombination rate, $L_3$, around a narrow $s$-wave magnetic Feshbach resonance of ${}^6\mathrm{Li}\text{−}{}^6\mathrm{Li}$ at 543.3 G. By examining both the magnetic field dependence and, especially, the temperature dependence of $L_3$ over a wide range of temperatures from a few $\mu \mathrm{K}$ to above $200\mu \mathrm{K}$, we show that three-atom recombination through a narrow resonance follows a universal behavior determined by the long-range van der Waals potential and can be described by a set of rate equations in which three-body recombination proceeds via successive pairwise interactions. We expect the underlying physical picture to be applicable not only to narrow $s$ wave resonances, but also to resonances in nonzero partial waves, and not only at ultracold temperatures, but also at much higher temperatures.

• Received 3 January 2018

DOI:https://doi.org/10.1103/PhysRevLett.120.193402