Magneto-optical trap of silver and potassium atoms

We demonstrate a dual magneto-optical trap (MOT) of $^{109}\mathrm{Ag}$ and $^{39}\mathrm{K}$. For silver, a decreasing-field Zeeman slower loads a MOT of $1.5\ifmmode\times\else\texttimes\fi{}{10}^{8}$ atoms at a temperature of 0.74(5) mK, with laser cooling occurring primarily on the ${D}_{2}$ line of $4{d}^{10}5s\phantom{\rule{0.28em}{0ex}}^{2}S_{1/2}\ensuremath{\rightarrow}5p\phantom{\rule{0.28em}{0ex}}^{2}P_{3/2}$ at 328 nm. We create a Ag ``dark spot MOT,'' where shelving the atoms in a dark state enhances the captured atom number by a factor of 2 and the lifetime by a factor of 4. For potassium, we obtain $2\ifmmode\times\else\texttimes\fi{}{10}^{8}$ trapped atoms, and further cooling on the ${D}_{1}$ transition via gray molasses results in a cloud of $1.2\ifmmode\times\else\texttimes\fi{}{10}^{8}$ atoms at $7(1)\phantom{\rule{0.28em}{0ex}}\textmu{}\mathrm{K}$. We observe evidence of photoionization loss of the K MOT in the presence of Ag laser-cooling light, necessitating sequential rather than simultaneous loading for the two species. Our results on Ag point to simple and general laser cooling strategies for other coinage metals (Au, Cu). Furthermore, this work lays the foundation for the production of alkali-metal--coinage-metal degenerate quantum mixtures and highly polar molecules.