Laser-Experiments with Single Atoms and the Test of Basic Quantum Phenomena

F. Diedrich, Jonas Krause, Gerhard Rempe +2 more

HERBERT WALTHER

In this paper, recent experiments of our group performed with single atoms in cavities and traps are summarized. In the first part, experiments with the one-atom maser are described dealing with the generation of number states of the photon field. In the second part of the paper, the spectroscopy of a single trapped In + ion is discussed being performed with the aim of realizing a new frequency standard in the optical range.

HERBERT WALTHER

. In this paper experiments performed with the one-atom maser are reviewed. Furthermore, possible experiments to test basic quantum physics are discussed. Introduction, the One-Atom-Maser The most promising avenue to study the generation process of radiation in lasers and masers is to drive a maser consisting of a single mode cavity by single atoms. This system, at first glance, seems to be another example of a Gedanken-experiment treated in the pioneering work of Jaynes and Cummings (1963), but such a one-atom maser (Meschede, Walther and Müller, 1985) really exists and can in addition be used to study the basic principles of radiation-atom interaction. The advantages of the system are: it is the first maser which sustains oscillations with less than one atom on the average in the cavity, this setup allows to study in detail the conditions necessary to obtain nonclassical radiation, especially radiation with sub-Poissonian photon statistics in a maser system directly in a Poissonian pumping process, and it is possible to study a variety of phenomena of a quantum field including the quantum measurement process. What are the tools that make this device work: It was the enormous progress in constructing superconducting cavities together with the laser preparation of highly excited atoms – Rydberg atoms – that have made the realization of such a one-atom maser possible.

HERBERT WALTHER

HERBERT WALTHER

F. Diedrich, Jonas Krause, Gerhard Rempe +2 more

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.>