Three-Dimensional Manipulation of Ultracold Atoms using Optical Tweezers

Abstract

This thesis describes the design and construction of a three-dimensional optical tweezer system. The three-dimensional aspects were constructed as a modular upgrade to a previously existing one-dimensional system and were characterised using 87Rb with avenues for future research using 40K in mind. The three-dimensional optical tweezer system was used to demonstrate multiple Bose-Einstein condensation in horizontal and vertical planes and gravitationally driven atomic collisions.

In order to take advantage of the three-dimensional nature of the optical tweezer system and to build capabilities with Rydberg quantum optics, vortex lattice studies and atom interferometry, a vertical imaging path was added to the existing experiment. Compared with the existing horizontal imaging path, the vertical imaging path has higher spatial resolution. A magnetic levitation scheme was implemented to prevent depth of focus issues due to atoms falling under the influence of gravity during ballistic expansion in time-of-flight. The levitation scheme was also used to increase the maximum time-of-flight using the horizontal imaging path by more than a factor of two. The improved resolution enabled observation of matter wave interference fringes for the first time in the Kjaergaard lab, which is a first step towards the study of quantum vortices.