Confinement of an alkaline-earth element in a grating magneto-optical trap

Cold alkaline-earth atoms are a promising platform for a variety of quantum technologies, in particular for atomic clocks. Such experiments often use a magneto-optical trap (MOT) for initial cooling and trapping, which usually requires a large setup and fine tuned alignment, limiting their potential applications. Here we demonstrate the first grating MOT of strontium, a compact alternative to the typical six-beam MOT. In this MOT, atoms are loaded from a small dispenser source and trapped with the diffraction off of a nanofabricated grating. Thus, such a MOT only uses a single input beam, which cuts down on space and alignment requirements. Our $^{88}$Sr MOT has approximately $4 \times 10^6$ atoms with a temperature of around 5 mK, and a vacuum limited lifetime of over 1 s. These results indicate that compact grating MOT systems could be used for clocks or other quantum devices with alkaline-earth atoms.