For quantum technologies, such as quantum computers, we can use individual molecules as building blocks. Molecules are all around us, but anyone wishing to trap them one by one in a controlled manner soon encounters problems. To do this, molecules must be cooled to just one millionth of a degree above absolute zero. However, collisions between molecules can cause them to escape from their traps. Understanding the collision dynamics at low temperatures and preventing this loss, in order to then efficiently load molecules into a lattice of traps, are central to this thesis.
By utilising the internal structure of molecules, it is possible to realise not only attractive but also repulsive interactions between molecules, which significantly reduce collision-induced loss. Quantum mechanical collision theory is used to characterise the properties of these different interactions. The controlled repulsive interactions are then applied in various strategies to trap molecules individually within a lattice as efficiently as possible, with predicted filling percentages of up to 90 per cent.
This thesis thus demonstrates how a detailed understanding of molecular collisions can be used to better control molecules. This opens up new avenues for future applications of molecules in quantum technology.
Etienne Walraven (1997) completed two bachelor’s degrees in Molecular Life Sciences and Mathematics at Wageningen University and Radboud University respectively. He then obtained his Master’s degree in Molecular Sciences, specialising in Physical Chemistry, cum laude from Radboud University in 2022. He then began his PhD research in the Department of Theoretical & Computational Chemistry, focusing on the quantum mechanical collision theory of ultracold molecules. In addition, he served as chair of the PhD Panel at the Institute for Molecules and Materials for two years. He is currently working as a postdoctoral researcher at Purdue University in the United States.