The Chip-Scale Atomic Clock - Coherent Population Trapping vs. Conventional Interrogation

Abstract : Symmetricom-TRC has undertaken a development effort to produce a prototype chip-scale atomic clock "CSAC". The overall architecture of the CSAC and, in particular, the physics package, must be defined early in the project, prior to the onset of a large-scale engineering effort. Within the constraints imposed by the performance goals of the project, we have recognized two possible schemes for interrogating the ground-state hyperfine frequency of the gaseous atomic ensemble: the conventional double-resonance technique and the coherent population trapping technique. In this paper, we describe a laboratory apparatus, which allows for in situ comparison of the two techniques, without the ambiguities associated with comparing data from disparate experiments. Data are presented comparing the short-term stability resultant of the two techniques, as well as environmental sensitivity to resonance cell temperature, laser intensity, and RF power.