Rapid axial loading of a grating MOT with a cold-atom beam

TL;DR

This paper demonstrates a rapid axial loading method for grating magneto-optical traps (gMOTs) using a cold-atom beam, significantly increasing atomic flux for portable quantum devices.

Contribution

It introduces and experimentally validates axial loading of gMOTs from cold-atom beams, overcoming limitations of traditional vapour-loading methods.

Findings

Achieved a loading rate of 2.1 x 10^9 atoms per second.

Numerical simulations show unbalanced diffracted beams hinder radial loading.

Axial loading effectively injects atoms into the trap, enabling high-flux operation.

Abstract

Laser-cooled atoms are increasingly being used to realise practical quantum devices, motivating the development of compact and robust atom sources. Grating magneto-optical traps (gMOTs) simplify the cold-atom source architecture but are typically vapour-loaded and provide limited atomic flux. Here we explore the loading of gMOTs from cold-atom beams. We numerically simulate loading to show that unbalanced diffracted beams deflect incoming atoms away from the trap centre, thereby strongly constraining radial loading. In contrast, axial loading injects atoms directly into the trapping volume and largely avoids these effects. We experimentally demonstrate rapid axial loading of a gMOT, achieving loading rates of $2.1 \times 10^9$ atoms~s$^{-1}$ using a moving optical molasses to transfer atoms from a 2D MOT into the gMOT. These results establish axial loading as a robust route to high-flux gMOT operation for portable cold-atom systems.