Single Sr Atoms in Optical Tweezer Arrays for Quantum Simulation

We report on the realization of a platform for trapping and manipulating individual ⁸⁸Sr atoms in optical tweezers. A first cooling stage based on a blue shielded magneto-optical trap (MOT) operating on the ^1S₀ -> ^1P₁ transition at 461 nm enables us to trap approximately 4times 10⁶ atoms at a temperature of 6.8 mK. Further cooling is achieved in a narrow-line red MOT using the ^1S₀ -> ^3P₁ intercombination transition at 689 nm, bringing 4times 10⁵ atoms down to 5 μK and reaching a density of approx 10¹⁰ cm^-3. Atoms are then loaded into 813 nm tweezer arrays generated by crossed acousto-optic deflectors and tightly focused onto the atoms with a high-numerical-aperture objective. Through light-assisted collision processes we achieve the collisional blockade, which leads to single-atom occupancy with a probability of about 50\%. The trapped atoms are detected via fluorescence imaging with a fidelity of 99.986(6)\%, while maintaining a survival probability of 97(2)\%. The release-and-recapture measurement provides a temperature of 12.92(5) μK for the atoms in the tweezers, and the ultra-high-vacuum environment ensures a vacuum lifetime higher than 7 min. These results demonstrate a robust alkaline-earth tweezer platform that combines efficient loading, cooling, and high-fidelity detection, providing the essential building blocks for scalable quantum simulation and quantum information processing with Sr atoms.