Bouncing Atoms

Radiation pressure by evanescent waves
Ultracold rubidium atoms falling down and bouncing off an evanescent wave mirror. Images were taken by exposing the atoms with a short flash of laser light and recording the fluorescence by a digital CCD camera. The atoms bounce sideways due to radiation pressure inside the evanescent wave. (Image size: 1x1 cm2) [paper as PDF]

(click for video clip)

Inelastic bouncing
Ultracold 87Rb atoms bouncing inelastically on an evanescent wave mirror. Atoms were released in one hyperfine state (F=1) and detected in the other (F=2). Note the diffuse tail of fast atoms.