We demonstrate the two-color cooling and trapping of alkaline-earth atoms in a grating magneto-optical trap (GMOT). The trap is formed by a single incident laser beam together with four secondary beams that are generated via diffraction from a nanostructured wafer. A grating structure for a GMOT operating with strontium atoms is optimized and fabricated. We trap ${10}^6{}^{88}\mathrm{Sr}$ atoms on the ${}^1{S}_0{\to }^1{P}_1$ transition at $461\mathrm{nm}$ and transfer 25% of these atoms to the second cooling stage on the narrower ${}^1{S}_0{\to }^3{P}_1$ intercombination transition at $689\mathrm{nm}$, preparing a sample of $2.5\times {10}^5$ atoms at $5\mu \mathrm{K}$. These results demonstrate the applicability of the GMOT technology in conjunction with two widely differing wavelengths and enable the continued miniaturization of alkaline-earth-based quantum technologies like optical atomic clocks.

• Received 16 December 2021
• Revised 18 February 2022
• Accepted 15 March 2022
• Corrected 20 April 2022

DOI:https://doi.org/10.1103/PhysRevApplied.17.044002

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Published by the American Physical Society