Compact Optical Atomic Clock Based on a Two-Photon Transition in Rubidium

Extralaboratory atomic clocks are necessary for a wide array of applications (e.g., satellite-based navigation and communication). Building upon existing vapor-cell and laser technologies, we describe an optical atomic clock, designed around a simple and manufacturable architecture, that utilizes the 778-nm two-photon transition in rubidium and yields fractional-frequency instabilities of 4 x 10(-13) / root tau(s) for tau from 1 to 10 000 s. We present a complete stability budget for this system and explore the required conditions under which a fractional-frequency instability of 1 x 10(-15) can be maintained on long time scales. We provide a precise characterization of the leading sensitivities to external processes, including magnetic fields and fluctuations of the vapor-cell temperature and 778-nm laser power. The system is constructed primarily from commercially available components, an attractive feature from the standpoint of the commercialization and deployment of optical frequency standards.