Progress on a Tactical Ytterbium Microwave Ion Clock

Abstract

Stable and accurate timekeeping is essential in today’s commercial and military applications. For decades, the 5071A Cesium beam clock has been the mainstay for long-term holdover in strategic applications for its unmatched performance. However, is too large, power hungry and cumbersome for most mobile platforms. To enable improved performance in lower size, weight and power applications, a new physics solution is required over traditional clock technology. In this paper we will present our Ytterbium microwave ion clock progress as a small form factor, high performance clock for use in military and commercial applications where portability is critical. Our device targets maximum performance improvement over traditional methods while minimizing technical risk, leveraging existing manufacturing, and targeting the lowest possible size, power and cost. The Physics Package includes a linear quadrupole trap, an electron gun (e-gun) ionizer, a passive getter pump and a Yb oven. We use electron impact ionization to load Ytterbium-171 ions which are cooled down to room temperature using buffer gas. Interaction-time limited Rabi spectroscopy using microwave radiation at 12.6 GHz is performed. The resulting microwave Rabi linewidth is used for closed-loop clock operation. Concurrent work is underway to develop a 369 nm Distributed Bragg Reflector laser which is essential for robust operation of the clock. We will discuss the specifications, the detailed design of our Ytterbium Microwave Ion Clock, the first assembled Physics Package and related preliminary test results.