Laser experiments with single atoms as a test of basic physics

Two experiments with single atoms are reviewed. In the first experiment, the interaction of a single Rydberg atom with a single mode of an electromagnetic field was investigated. The quantum collapse and revivals of the atomic inversion predicted by the Jaynes-Cummings model were demonstrated for the first time. In the second experiment, a single atomic ion stored in a radio-frequency trap was probed by resonance fluorescence. In the fluorescent light, antibunching and sub-Poissonian photon statistics were detected. Furthermore, `crystallization´ and `evaporation´ of few ions in a trap were observed as the stored ions were cooled by the laser light and heated by the radio-frequency field of the trap