SciPost Phys. 8, 038 (2020)

Quantum-state engineering requires the ability to manipulate small sets of particles at their individual level. For neutral atoms, optical tweezers, which use optical dipole forces to capture dielectric particles in a tightly focused laser beam, provide a unique tool to achieve this goal. Usually tweezers are created using high-numerical-aperture lenses with very short working distances. Dielectric surfaces close to the trapped atoms may lead to unwanted systematic errors in atom detection.

Niamh Christina Jackson and co-workers have now overcome this obstacle by constructing an optical tweezer with a working distance almost twice that of similar setups based on in-vacuo lenses. The lens design was optimized at wavelengths that are suitable for capturing and detecting strontium atoms. By demonstrating high-fidelity individual-atom isolation and number-resolved atom detection, the new tweezer has proved a promising building block of an ideal platform for further studying quantum physics.