Motional ground-state cooling of single atoms in state-dependent optical tweezers

TL;DR

This paper introduces a novel laser cooling method for single atoms in optical tweezers that overcomes traditional constraints, enabling efficient ground-state cooling and facilitating large atom array assembly for quantum technologies.

Contribution

The authors develop and demonstrate a new cooling scheme using frequency chirping of cooling light, applicable even when standard magic trap conditions are not met.

Findings

Achieved ground-state populations comparable to magic trap experiments

Demonstrated the scheme with $^{88}$Sr atoms in optical tweezers

Enabled light-assisted collisions for large atom array assembly

Abstract

Laser cooling of single atoms in optical tweezers is a prerequisite for neutral atom quantum computing and simulation. Resolved sideband cooling comprises a well-established method for efficient motional ground-state preparation, but typically requires careful cancellation of light shifts in so-called magic traps. Here, we study a novel laser cooling scheme which overcomes such constraints, and applies when the ground-state of a narrow cooling transition is trapped stronger than the excited state. We demonstrate our scheme, which exploits sequential addressing of red sideband transitions via frequency chirping of the cooling light, at the example of $^{88}$Sr atoms, and report ground-state populations compatible with recent experiments in magic tweezers. The scheme also induces light-assisted collisions, which are key to the assembly of large atom arrays. Our work enriches the toolbox for tweezer-based quantum technology, also enabling applications for tweezer-trapped molecules and ions that are incompatible with resolved sideband cooling conditions.