An apparatus for immersing trapped ions into an ultracold gas of neutral atoms

TL;DR

This paper presents a hybrid apparatus combining a Bose-Einstein condensate system and a linear Paul trap to study ultracold atom-ion interactions, enabling controlled collision experiments with high stability.

Contribution

The novel setup separates ion and atom production regions and combines them via optical lattice transport, improving stability and experimental access for ultracold atom-ion collision studies.

Findings

Successful integration of BEC and ion trap systems

Precise control of atom-ion relative positioning

Demonstrated transport of atomic cloud over 30 cm

Abstract

We describe a hybrid vacuum system in which a single ion or a well defined small number of trapped ions (in our case Ba$^+$ or Rb$^+$) can be immersed into a cloud of ultracold neutral atoms (in our case Rb). This apparatus allows for the study of collisions and interactions between atoms and ions in the ultracold regime. Our setup is a combination of a Bose-Einstein condensation (BEC) apparatus and a linear Paul trap. The main design feature of the apparatus is to first separate the production locations for the ion and the ultracold atoms and then to bring the two species together. This scheme has advantages in terms of stability and available access to the region where the atom-ion collision experiments are carried out. The ion and the atoms are brought together using a moving 1-dimensional optical lattice transport which vertically lifts the atomic sample over a distance of 30$\,$cm from its production chamber into the center of the Paul trap in another chamber. We present techniques to detect and control the relative position between the ion and the atom cloud.