Experimental Studies of Atom Diffraction and The Mechanical Forces of Light on Atoms

Abstract

Publisher Summary This chapter presents a few experiments on light forces, which were done in a high-resolution apparatus where the momentum transferred by light to a monochromatic beam of atoms prepared in a single hyperfine state could be measured to ∼ 5%. The momentum resolution was less than ħk—the momentum of a single photon—thus revealing the finest details that could be presented. The optical interaction parameters were known well enough to permit quantitative comparisons with various theories of light forces. In the experiments described in the chapter, diffraction of atoms by a standing light wave in the regime was observed where the laser and atomic beams were orthogonal. The interaction time was short and the detuning of the laser frequency from the atomic transition frequency was much larger than the laser intensity, because of which spontaneous emission was negligible. It was further observed that the diffraction of atoms moved through a standing light wave with the same parameters used for the Kapitza-Dirac diffraction. The diffraction of atoms by a standing light wave was observed in the regime where the interaction time was long enough for the atoms to slosh back and forth in the valleys of the standing-wave potential. Restricted, unidirectional momentum transfer was also observed where the scattering pattern was dramatically altered by tilting the atomic beam with respect to the laser beam at very small angles.