Cold atom micro primary standard (CAMPS)

Abstract

We present progress towards a primary frequency standard with substantial reduction in size, weight, and power over the state of the art. Our clock is based on the microwave hyperfine transition in rubidium 87. Unique to this effort, our focus is on special design considerations and engineering trades to realize a primary frequency standard in an ultimate 5 cc form factor, with 50 mW power consumption, and which is compatible with a robust, high-volume manufacturing process. In our approach, atoms are laser cooled from a background vapor into a magneto-optical trap. The magnetic and optical trapping forces are extinguished, allowing the atoms to freely expand, and Ramsey spectroscopy is performed to measure the clock transition between the F = 1 and F = 2 hyperfine states. Key to size reduction is the use of laser cooled atoms to achieve narrow line widths in a small size, and the ability to perform all the clock functions (sample preparation, spectroscopy, and read-out) in one physical location. Using a miniaturized physics package, signal-to-noise ratios greater than 100 and clock line quality factors greater than 1E+8 have been achieved. We also discuss limiting factors and prospects for improvement.