Magneto-Optical Trap in a Hollow-Core Fiber: Simulation and Optimization

Hsuan-Yu Lin^1*, Shau-Yu Lan^1,2, Wui Seng Leong^1,2

¹Department of Physics, National Taiwan University, Taipei City, Taiwan
²Institute for Atomic and Molecular Sciences, Academia Sinica, Taipei City, Taiwan

* Presenter:Hsuan-Yu Lin, email:B10202015@ntu.edu.tw

This study investigates the trapping and cooling of ⁸⁷Rb atoms in a hollow-core fiber, divided into two key stages. In the first stage, atoms from a 2D magneto-optical trap (MOT) are captured near the fiber using a 1064 nm dipole potential. The initial parameters of the 2D MOT, such as center-of-mass velocity and beam alignment, are systematically varied to study their influence on the atom density inside the fiber. By calculating the density distribution under different conditions, we identify optimal configurations for efficient loading.
In the second stage, the atoms captured near the fiber are cooled using 1D MOT techniques within the fiber. The simulations focus on the behavior of the atomic ensemble by calculating the saturation number of atoms, the atomic density distribution inside the fiber, and the axial temperature variation to evaluate the cooling performance.
The results show that precise tuning of the initial parameters of the 2D MOT and the dipole potential alignment significantly enhances the atom capture probability. Additionally, the use of 1D MOT cooling enables the creation of dense and ultracold atomic ensembles within the confined geometry of the hollow-core fiber. These findings demonstrate the potential for achieving high-density, low-temperature atomic clouds, which are essential for applications in quantum technologies such as quantum memories, nonlinear optics, and precision sensing.

Keywords: Atomic physics, Hollow-core fiber, Magneto-optical trap