Optical transport and manipulation of an ultracold atomic cloud using focus-tunable lenses

TL;DR

This paper demonstrates a compact optical system using focus-tunable lenses to efficiently transport and manipulate ultracold atomic clouds with high precision and minimal heating, enabling dynamic control of trapping conditions.

Contribution

It introduces a novel focus-tunable lens setup for transporting ultracold atoms over long distances while maintaining constant trap conditions and allowing dynamic beam shaping.

Findings

Near-unity atom transport efficiency

Minimal heating of a few microkelvin

Effective focus stability compensation

Abstract

We present an optical setup with focus-tunable lenses to dynamically control the waist and focus position of a laser beam, in which we transport a trapped ultracold cloud of 87-Rb over a distance of 28 cm. The scheme allows us to shift the focus position at constant waist, providing uniform trapping conditions over the full transport length. The fraction of atoms that are transported over the entire distance comes near to unity, while the heating of the cloud is in the range of a few microkelvin. We characterize the position stability of the focus and show that residual drift rates in focus position can be compensated for by counteracting with the tunable lenses. Beyond being a compact and robust scheme to transport ultracold atoms, the reported control of laser beams makes dynamic tailoring of trapping potentials possible. As an example, we steer the size of the atomic cloud by changing the waist size of the dipole beam.