Portable Microwave Cold Atomic Clock

We present a technical approach for the design of a small, portable, microwave cold atomic clock that meets the frequency stability requirement of less than 1X10-12 at 1 s averaging time and less than 5X10-15 for an averaging time of 1 day in the following size weight and power requirements (SWaP). Our approach is based on a laser-cooled atom microwave fountain clock that uses precision microwave spectroscopy of the frequency splitting between two internal, long-lived states of an atom to stabilize the frequency of a quartz crystal oscillator. The physics package we propose to study in Phase I of this program will be designed using the knowledge gained from Honeywell?s efforts under the DARPA IMPACT program. We also propose the architecture for a miniature microwave synthesizer with size less than 0.25L, weight less than 0.25kg and consuming less than 3.5 W of power. These size weight and power constraints are consistent with the design of the small portable clock. The miniature synthesizer has expected short term frequency stability less than 1X10-12 which is required for the proposed clock design.