Engineering the interactions and dynamics of ultracold atom gases

Ultracold atoms are used to study various fundamental physics, including many-body system, nonequilibrium dynamics, and find many applications in quantum computing and quantum sensing. In this thesis, we studied the dynamics of ultracold atom gases with controllable two-body interactions. One of the major concerns is to manipulate the atomic states with electromagnetic fields. Here, we will show four projects associated with this topic. The first project is about the Sagnac interferometer based on trapped Bose-Einstein condensate. We explored the dynamics of the atoms and their relation to the sensitivity. We came up with an optimised driving field, and the performance is examined with interactions taken into consideration. The second project is about the quantum dynamics of bosonic atoms in an optical lattice with long-range interactions by Rydberg-dressing. It has been widely studied due to its controllable strength, length and anisotropy, which paves the new approach to engineering exotic quantum states and improving the performance of quantum devices. We found that phase transitions of Mott-insulator, superfluid supersolid, and density wave during a quench process. The correlation of the atoms is studied which reveals the properties of long-range interactions. The third project shows new designs of the magneto-optical trap for atom cooling. They are proposed to be manufactured by 3D printing technology. We simulated their performance and optimised the geometric parameters. The time-response and impedance have also been analysed. The fourth project studies the ground state of Rydberg-dressed fermions from the perspective of Fermi surface deformation. We calculated the deformation manifested by the aspect ratio and the appearance of Cooper pairs. The power-law scaling relations have been found with respect to the laser field, atom density and the quantum number of Rydberg states.