Magneto-optical trap of a Group III atom

Abstract

We realize the first magneto-optical trap of an atom in main group III of the Periodic Table. Our atom of choice (indium) does not have a transition out of its ground state suitable for laser cooling; therefore, laser cooling is performed on the $\lvert 5P_{3/2},F=6 \rangle \rightarrow \lvert 5D_{5/2},F=7 \rangle$ transition, where $\lvert 5P_{3/2},F=6 \rangle$ is a long-lived metastable state. Optimization of our trap parameters results in atoms numbers as large as $5\times10^8$ atoms with temperatures of order 1 mK. Additionally, through trap decay measurements, we infer a one-body trap lifetime of 12.3 s. This lifetime is consistent with background gas collisions and indicates that our repumpers have closed all leakage pathways. We also infer a two-body loss rate of $1.6\times 10^{-11}\ \mathrm{cm^3/s}$, which is comparable to those measured in alkali atoms. The techniques demonstrated in this work can be straightforwardly applied to other group III atoms, and our results pave the way for realizing quantum degenerate gases of these particles.