This thesis discusses experiments on the all-optical trapping and manipulation of laser-cooled metastable argon atoms at a surface. A magneto-optical surface trap (MOST) has been realized and studied. This novel hybrid trap combines a magneto-optical trap at a metallic surface with an optical evanescent-wave atom mirror. It allows for laser-cooling and trapping of atoms in contact with an evanescent light field that separates the atomic cloud from the surface by a fraction of an optical wavelength. Based on this work, the continuous loading of a planar matter waveguide has been demonstrated. Loading into the waveguide, which was formed by the optical potential of a red-detuned standing light wave above the surface, was achieved via evanescent-field optical pumping from the MOST in sub-µm distance from the surface. In subsequent experiments, several light-induced atom-optical elements have been demonstrated in the planar waveguide geometry, including a continuous atom source, a switchable channel guide, an atom detector and an optical surface lattice. The source, the channel and the detector have been combined to form a simple atom-optical integrated circuit.
This thesis describes the construction and characterisation of a unique cold argon atom source for sympathetic cooling of molecules. Argon atoms were laser cooled from their lowest lying metastable state using the 4s[3/2]2 → 4p[5/2]3 transition at 811.5 nm. A magneto-optical trap (MOT) was used to cool the metastable argon (Ar*) atoms to 73.2 ± 0.4 μK and trap them at a density of 3.93 × 10^9 cm-3. Cooling was facilitated using an external-cavity diode laser which was frequency-stabilised to the cooling transition using a magnetic dichroism technique. This was the first application of this technique to a plasma operated at our pressures where the applied magnetic field affected the gas behaviour. The Ar* atoms in the MOT were used to demonstrate chirped optical Stark acceleration for the first time. Atoms were accelerated up to velocities of 191 ± 1 ms-1 while maintaining narrow energy spreads in the accelerated ensemble (30-100 mK). The acceleration occurred over tens of nanoseconds and on micrometre length scales. Control over the number of particles accelerated was achieved by tailoring the depth of the optical lattice potential. Monte Carlo numerical simulations of acceleration were used to fit experimental results and study the dynamics of particles over the acceleration duration. Trapping of Ar* atoms in a quasi-electrostatic trap (QUEST) has also been demonstrated. The QUEST was formed at the focus of a 100 W laser beam with a wavelength of 10.6 μm. A trap lifetime of 18.3 ± 0.3 ms was measured.
We trap cold, ground state argon atoms in a deep optical dipole trap produced by a buildup cavity. The atoms, which are a general source for the sympathetic cooling of molecules, are loaded in the trap by quenching them from a cloud of laser-cooled metastable argon atoms. Although the ground state atoms cannot be directly probed, we detect them by observing the collisional loss of cotrapped metastable argon atoms and determine an elastic cross section. Using a type of parametric loss spectroscopy we also determine the polarizability of the metastable
4s[3/2]2 state to be $(7.3\ifmmode\pm\else\textpm\fi{}1.1)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}39}\text{ }\text{ }\mathrm{C}\text{ }{\mathrm{m}}^{2}/\mathrm{V}$. Finally, Penning and associative losses of metastable atoms in the absence of light assisted collisions, are determined to be $(3.3\ifmmode\pm\else\textpm\fi{}0.8)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}\text{ }\text{ }{\mathrm{cm}}^{3}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$.