Atomic frequency standards are very stable and accurate frequency sources. They are now used, for example, in high-speed communication, in navigation systems and in time-keeping. This study, which examines present knowledge regarding the operation of such devices, is designed to be used by the newcomer to the field as well as by the experienced researcher. The text describes some applications of quantum electronics including experimental methods, fresh approaches to physical theory and techniques of calculation which workers in other fields may find can be transposed to their own. For readers who wish to explore the field more deeply, all the appropriate mathematical derivations are given in appendices and there is an extensive reference list.
