Single-atom imaging of 40K atoms via raman sideband cooling

The focus of this thesis is the trapping, cooling and imaging of fermionic potassium atoms in optical lattice potentials. Our experiment is capable of cooling 40K atoms to a T /TF of 0.18, well into the degenerate Fermi-gas regime. We then load the atoms into a 3D optical lattice and prepare ∼ 500 atoms in one anti-node of the vertical lattice. This 2D ‘layer’ of atoms is imaged with single-site resolution, giving us access to the behaviour of quantum many-body systems in periodic lattice potentials. The first chapter motivates why this system is so keenly interesting. The experiment aims to function as an analogue quantum simulator for one of the founding questions of quantum theory: the classically inexplicable behaviour of correlated electrons in solid state systems. The second chapter briefly explores the techniques of preparation and control of dilute ultracold gases. The bulk of the thesis, chapters 3 and 4, deal with the design and optimization of the imaging scheme for site-resolved imaging of 40K atoms. In chapter 5, we describe our work with a rubidium quantum-gas experiment, particularly on the laser cooling and state preparation of 85Rb atoms. Finally, we conclude with a look back on what we were able to achieve and learn as well as a look forward to the future of the 40K and 85Rb experiments. Our results and contributions to the broader field are as follows: We have achieved site-resolved imaging of 40K atoms with ∼ 5% losses via Raman sideband-cooling. Our work characterizing the imaging scheme and the associated challenges adds to the understanding of the vital and broadly applicable technique of RSC. We also compare these results against electromagnetically-induced transparency (EIT) cooling. As we are possibly the only quantum-gas microscope experiment to use both Raman sideband and EIT cooling, we are uniquely positioned to benchmark both techniques. Additionally, I numerically simulate light-assisted heating and tunneling rates of 40K atoms in the optical lattice via the quantum trajectory technique. The simulations enhance our understanding of our imaging technique as well as contributing to the more general understanding of challenges associated with optically trapping 40K atoms. Finally, our work on implementing grey-molasses cooling of 85Rb has not been demonstrated before. This marks a step forwards in the laser cooling of 85Rb both in quantum-gas microscopes and other cold-atom experiments.The focus of this thesis is the trapping, cooling and imaging of fermionic potassium atoms in optical lattice potentials. Our experiment is capable of cooling 40K atoms to a T /TF of 0.18, well into the degenerate Fermi-gas regime. We then load the atoms into a 3D optical lattice and prepare ∼ 500 atoms in one anti-node of the vertical lattice. This 2D ‘layer’ of atoms is imaged with single-site resolution, giving us access to the behaviour of quantum many-body systems in periodic lattice potentials. The first chapter motivates why this system is so keenly interesting. The experiment aims to function as an analogue quantum simulator for one of the founding questions of quantum theory: the classically inexplicable behaviour of correlated electrons in solid state systems. The second chapter briefly explores the techniques of preparation and control of dilute ultracold gases. The bulk of the thesis, chapters 3 and 4, deal with the design and optimization of the imaging scheme for site-resolved imaging of 40K atoms. In chapter 5, we describe our work with a rubidium quantum-gas experiment, particularly on the laser cooling and state preparation of 85Rb atoms. Finally, we conclude with a look back on what we were able to achieve and learn as well as a look forward to the future of the 40K and 85Rb experiments. Our results and contributions to the broader field are as follows: We have achieved site-resolved imaging of 40K atoms with ∼ 5% losses via Raman sideband-cooling. Our work characterizing the imaging scheme and the associated challenges adds to the understanding of the vital and broadly applicable technique of RSC. We also compare these results against electromagnetically-induced transparency (EIT) cooling. As we are possibly the only quantum-gas microscope experiment to use both Raman sideband and EIT cooling, we are uniquely positioned to benchmark both techniques. Additionally, I numerically simulate light-assisted heating and tunneling rates of 40K atoms in the optical lattice via the quantum trajectory technique. The simulations enhance our understanding of our imaging technique as well as contributing to the more general understanding of challenges associated with optically trapping 40K atoms. Finally, our work on implementing grey-molasses cooling of 85Rb has not been demonstrated before. This marks a step forwards in the laser cooling of 85Rb both in quantum-gas microscopes and other cold-atom experiments