Gravito-optical Surface Trap With Semi-Gaussian Beam And Its Intensity Gradient Cooling

Laser cooling and trapping of neutral atoms, include the intensity gradient cooling and optical dipole traps with blue-detuned laser field are briefly introduced in this thesis. Also, the principle of atomic mirror and the schemes of two atomic mirrors, i.e., evanescent-wave mirror and semi-Gaussian beam atomic one, are introduced. In addition, we introduced the principle of the atom interferometers and recent experimental results.We propose a novel gravito-optical surface trap (GOST) for neutral atoms, which is composed of a reduced semi-Gaussian-beam (SGB) atomic mirror and a hollow laser beam. As compared with evanescent-wave atomic mirror, the reduced SGB mirror has some new and unique advantages: such as high intensity gradient force and high optical potential, and without van der Waals attractive potential. From Fresnel diffractive theory, we calculate the relative intensity distribution of the reduced semi-Gaussian beam in the x direction, and discuss the relationship between the relative intensity and the waist of laser beam, and find that the relative intensity is not nearly related to the waist. We fit the average absolute intensity distribution near the surface of the SGB mirror in order to calculate the optical potential, dipole force and simulate the cooling effect. We analyze the principle of intensity-gradient cooling, and present the theoretical result. Also, we perform the Monte-Carlo simulations, and obtain some new and important results, including the time evolution of the height of atom cloud and the horizontal position, the dependence of the final equilibrium rms momentum of atoms on the SGB power, and its detuning and so on.When the beam waist along the direction of semi-ellipse-Gaussian beam (SEGB) is the same as one of the SGB, due to a smaller cross area, the absolute intensity distribution, optical potential and dipole force of the SEGB is larger than that of the SGB with the same incident laser power, So, in the second part of this thesis, we use SEGB, instead of SGB, to form a new gravito-optical surface trap (GOST). We calculate the absolute intensity, optical potential and dipole force of the SEGB, and simulate the dynamic process of the SEGB intensity-gradient cooling of atoms in the GOST. Our study shows...