Magneto-optical-trap loading in a large optical-access experiment

TL;DR

This paper investigates the optimization of strontium magneto-optical trap (MOT) loading using a combined experimental, numerical, and analytical approach, focusing on high optical access and metastable-state dynamics.

Contribution

It introduces a novel configuration with high optical access, analyzes the role of metastable states in transfer efficiency, and develops a comprehensive simulation tool for optimizing MOT loading.

Findings

Optimal transfer depends on metastable-state shelving to 5s5p 3P2.

Dark-state loss to 5s5p 3P0 limits transfer efficiency.

The simulation accurately models the entire trap loading process.

Abstract

We present an experimental, numerical, and analytical study of strontium magneto-optical trap (MOT) loading from a cold atomic beam in a configuration optimized for high numerical aperture optical tweezers. Our approach orients the beam flow along the MOT symmetry axis to reduce the experimental complexity and maximize the overall optical access into the scientific region of study. We use a moving molasses technique to enable this configuration and show that its performance depends critically on metastable-state shelving (to 5s5p 3P2) during the atom transfer to the three-dimensional (3D) MOT. Furthermore, we find that the parameters for optimal transfer efficiency are bounded by dark-state loss (to 5s5p 3P0) in the trap region where repumping is present. These observations are verified to great degree of accuracy using both our developed analytical and numerical models. The corresponding 3D simulation tool is used to perform a comprehensive study of the trap loading dynamics, beginning at the oven exit and ending at the 3D MOT, demonstrating its effectiveness in optimizing an effusive oven experiment.