Investigation Of Cooling Of Cesium Atoms In 3D Optical Lattice And Light Shift Of Atomic Energy Level

The interaction of light field and atoms is an effective approch of controlling atoms' movement. Optical lattice, because it can supply the controlling of single or multi-entity, and can insulate atoms with the enviroment—minishing the decoherence of quantum system, becomes an important tool of quantum manipulation of atoms. Cold atom optical lattice is an important topic of quantum manipulation of atoms, especially with the development of quantum information processing these years, it is paid more attentions on quantum entanglement, quantum calculation and quantum register.Optical lattice can be classified into the near-resonance optical lattice and the far-off-resonance optical lattice according to detuning of optical lattice's laser to the atomic transition. The scattering rate of near-resonance optical lattice is bigger than the far-off-resonance optical lattice(but smaller than the resonation case), and has the Sisyphus cooling mechanism, so it can cool the cold atoms down efficiently. Its intensity hasn't spatial gradient, but the polarization period from laevogyrate circularity polarization to linear polarization and to dextrorotation circularity polarization leads to light shift of Zeeman states in ground state—restrict the atoms. But in the far-off-resonance optical lattice, the scattering rate is very small, and it hasn't any cooling mechanism, so the spatial gradient of intensity plays the primary role.Based on the magneto-optical trap (MOT) system, building a four-beam 3D optical lattice is implemented, the temperature and the lifetime of cold atoms in 3D in near-resonance optical lattice are measured, the parameter dependence is investigted. Light shifts of the far-off-resonance optical lattice and the single-focused-beam optical dipole trap are calculated. The main works are following:1. Study loading and cooling of cesium atoms in near-resonance 3D optical lattice: building the 3D optical lattice, realizing cesium atoms loading in red-detuned optical lattice based on Cs MOT and optical molasses; then by changing the intensity and frequency of optical lattice, parameter dependence of optical lattice and the lifetime of optical lattice are experimentally investigated.2.Calculate light shift of each level of Cs D₂ line in far-off-resonance optical lattice and single-focused-beam optical dipole trap: Considering the multi-level model (many upper states exsist), light shifts of 6P_3/2 and 6S_1/2 states of Cs D₂ line in far-off-resonance optical lattice and single-focused optical dipole trap are calculated and are compared with the results of two level model. Changing the laser's power and waist radius, light shift has been calculated. And also light shifts of Cs D₂ line and Rb D₂ line versus laser wavelength are calculated. Finally, the actual detuning is calculated when we realize optical molasses to decrease the temperature in optical dipole trap.