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We have experimentally demonstrated a material-independent mirror for atomic waves that uses the Fresnel diffraction at an array of parallel ridges. He* (2 3 S 1 ) and Ne* (1s 3 ) atomic waves were reflected coherently on a silicon plate with a microfabricated grating structure, consisting of narrow wall-like ridges. We measured the reflectivity at grazing incidence as a function of the incident velocity and angle. Our data show that the reflectivity on this type of mirror depends only on the distance between the ridges, the wavelength, and the incident angle, but is insensitive to the material of the grating structure. The reflectivity is observed to increase by 2 orders of magnitude, compared to that of a flat polished silicon surface, where the reflection is caused by the attractive surface potential. For He* atoms, the measured reflectivity exceeds 10% for normal incident velocities below about 25 cm=s.

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Resonance fluorescence of a single trapped ion is spectrally analyzed using a heterodyne technique. Motional sidebands due to the oscillation of the ion in the harmonic trap potential are observed in the fluorescence spectrum. From the width of the sidebands the cooling rate is obtained and found to be in agreement with the theoretical prediction.PACS: 32.80. Pj, 42.50.Lc, 42.50.Vk Since the first preparation of a single atom in a Paul trap and observation of its resonance fluorescence [1], investigation of this light has revealed a range of unique properties. Examples are its nonclassical nature [2] and the highly nonlinear response, in the form of sudden intensity jumps, of a multi-level atom to continuous laser excitation [3]. The fluorescence is, at the same time, a unique tool for determining the state of the atom. This is particularly obvious for a single particle where each photon emission marks the respective projection of the atomic wave function into the final state of the corresponding transition. It is also of great interest to study, through its resonance fluorescence, the motion of a single laser-excited particle, e.g. for investigating laser cooling schemes or in connection with proposals for quantum state manipulation or quantum information processing with trapped particles [4].

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