Dual Species Er-K Experiment for the Study of Impurities in a Dipolar Quantum Gas

Jiri Kucera - University of Oxford
2021 - PhD 1^st year report

In this report, I describe the current state of the Oxford dual-species dipolar quan tum gas experiment and my contribution to its completion during the first year of my DPhil studies. At the moment, production of large number (up to 108) of ultracold Erbium (Er) atoms is achieved by transverse cooling and Zeeman slowing via the 401 nm transition and by implementation of a Magneto-Optical Trap (MOT) that ad dresses the (narrow) 583 nm transition. Additional optical and vacuum systems are currently being built that will introduce cold Potassium (K) atoms into the dipolar Er bath. Both of these systems are discussed in detail. Specifically, the design and assembly process of the 2D+ MOT chamber for the K atoms is described and the mechanism as well as our specific realization of 39K / 41K cooling via the D1 and D2 lines is reported. In our setup and after the initial MOT stages, both the Er and K atoms will be sequentially loaded into a 1030nm crossed beam optical dipole trap (ODT), force-evaporated to quantum degeneracy and optically transported to a glass science cell for further experimentation. A simulation was created to optimize the evaporation process. We briefly describe the theory of dipole trapping, the specific geometry of our system and the thermodynamical model implemented in the sim ulation and present the reader with preliminary results. Furthermore, the physical relevance of dual species experiments is discussed in relation to dipole-dipole inter actions, polarons and more broadly impurity physics. Lastly, an attempt is made to present current state of the art in experimental dipolar cold atom physics and next steps are outlined that need to be taken in order to achieve our experimental goals.