Single Atom Masers and Lasers

HERBERT WALTHER

P. L. Knight

Zhi‐Ming Zhang

One-atom maser and one-atom laser are important experimental proving grounds in the study on cavity quantum electrodynamics(CQED).This paper reviews the studies on several types of one-atom masers and one-atom lasers,including the one-atom maser of Walther's group,the one-atom maser injected with ultracold atoms,the CQED system of Haroche's group,the one-atom laser with injected atoms,the one-atom laser with a single trapped ion,and the one-atom laser with a single trapped atom.The author introduces typical experimental systems and their main results,and also reviews relevant theoretical works.

HERBERT WALTHER

Modern methods of laser spectroscopy allow the study of single atoms or ions in an unperturbed environment. This has opened up interesting new experiments, an among them is the detailed study of radiation-atom coupling. This chapter reviews the following two experiments of this type: the single-atom maser and the study of the resonance fluorescence of a single stored ion. The simplest and most fundamental system for studying radiation-matter coupling is a single two-level atom interacting with a single mode of an electromagnetic field in a cavity. There is another aspect of the single-atom maser which is very interesting: the non-classical statistics of the photons in the cavity. The results obtained for the single-atom maser also give a new insight into the statistical properties of masers and lasers. A problem in radiation-matter interaction which has received a lot of interest is resonance fluorescence. The experiments to investigate antibunching in resonance fluorescence have been performed by means of laser-excited collimated atomic beams.

Jacques Vanier

Ning Lü

We show that the problem of a \ensuremath{\Lambda}-type (and also a V-type) three-level single-mode laser (maser) is isomorphic to that of a two-level single-mode laser (maser) under the conditions of energy-level degeneracy and equal decay rates. This correspondence reveals that lasing without population inversion can occur in the \ensuremath{\Lambda}-type system with or without an initial atomic coherence, and also gives immediately the master equation of the laser (maser) field. We analyze in detail the operational and noise properties of a \ensuremath{\Lambda}-type laser using a Fokker-Planck approach. We also present a vector model to visualize the population trapping and the absorption and emission processes in such a laser (maser) system.