Spindynamik von Alkaliatomen in Lichtfeldern

Abstract

This thesis reports on optically induced spin dynamics of alkali atoms. The experiments are performed both on a "7Li atomic beam and on "1"3"3Cs atoms trapped in a novel dipole force trap. The fictitious magnetic field that acts on alkali atoms in an off-resonant, circularly polarized laser field serves as an efficient tool for spatially localized in-beam and in-trap spin manipulation. In the atomic beam the ground state magnetic moments are prepared by optical pumping and sensitively detected by the fluorescence light. The spin precession induced by a fictitious magnetic field is studied in detail and used to create an in-beam spin-echo. The results clearly demonstrate that both D lines lead to a fictitious field of equal magnitude, yet their dispersive resonance shapes have an opposite sign. As a consequence, the effect of the field is enhanced between the D lines, and reduced on either side of the doublet. The atom trap consists of a far red-detuned standing light wave, oriented vertically and allowing for Stern-Gerlach selection of a magnetic substate. By comparing the trapping of a single substate with the simultaneous storage of all sublevels, the decay of spin polarization that results from photon scattering of trap light is measured. Furthermore it is shown that the fictitious magnetic field can easily induce an in-trap spin precession. The results obtained for the fictitious magnetic field are representative for any alkali species, since this field does not depend on the particular nuclear spin, as long as the detuning of the laser is large compared to the excited state hyperfine splitting. (orig.)SIGLEAvailable from TIB Hannover: RO 6920(1999,3) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman