Laser cooling refers to the techniques that cool atomic and molecular samples down to near absolute zero through the interaction with laser fields. Atoms absorb a photon and the transferred momentum generates force to lower the atom's velocity. The Doppler shift is associated with the motion of the atom, in which a moving atom always observes a slightly different frequency than the laser at rest. Based on the two-level system theory, this thesis studied the process of multiple sequences of adiabatic rapid passage by simulating the process of the interaction between optical forces and helium atoms. By studying the force map in parameter space, trying to understand the relationship between the average force and relevant laser parameters
Ω0 and
δ0 in the Rabi frequency. Furthermore, we studied the relationship between the average force and velocity by comparing the dragged atom model and moving atom model. We also studied the process of multiple sequences of adiabatic rapid passage by changing spontaneous emission, sweep range, pulse number for the interaction, exploring the distance between peaks that appear in the velocity distribution. The observational results will be presented in the thesis as well as the explanation. | 86 pages