Design, construction, and performance towards a versatile 87Rb and 41K BEC apparatus

Abstract

The possibility to mould and control pure quantum systems has been offered by the experimental observation of Bose-Einstein condensation, a unique phase of matter when macroscopic quantities of a gas occupy the lowest quantum state.Techniques for creating these degenerate gases vary from laboratory to laboratory; each offers an unique test bed for studying quantum physics on a macroscopic scale.This thesis reports on the experimental design, construction and performance of an apparatus to create two-component 87 Rb and 41 K condensates for studies of non-equilibrium dynamics.This thesis is broken down as follows. In Chapter 1, a brief overview of the history and status of Bose Einstein condensates is presented, to affirm the motivation behind our work. Chapter 2 then presents the fundamental theory and background information to understand how and why our experiment was built.Chapter 3 describes the bulk of the work undertaken at the beginning of this thesis. In particular it describes the design choices, construction and performance of the vacuum, and laser and magnetic coil systems that are the key structural elements of the apparatus. In particular the vacuum system is a two-component differentially pumped system designed to optimise the number and lifetime of trapped atoms. Another integral element of the vacuum chamber is the science cell that enables high optical access, and close physical, access to an atomic cloud.As a result, high resolution imaging, 980 nm resolution at 780 nm is expected with a commercial microscope objective lens. The laser system is carefully designed to best combine and deliver the seven different optical frequencies required to simultaneously trap and manipulate 87 Rb and 41 K atoms. The magnetic coil system also represents an integral component of the apparatus, responsible for trapping and transferring atoms in a quadrupole field. One pair of coils is able to have their current direction reversed in order to generate bias fields. This allows access to Feshbach resonances between the two species, once they have been iii condensed.