JPL Ultrastable Trapped Ion Atomic Frequency Standards

Recently, room temperature trapped ion atomic clock development at the Jet Propulsion Laboratory (JPL) has focused on three directions: 1) ultrastable atomic clocks, usually for terrestrial applications emphasizing ultimate stability performance and autonomous timekeeping; 2) new atomic clock technology for space flight applications that require strict adherence to size, weight, and power requirements; and 3) miniature clocks. In this paper, we concentrate on the first direction and present a design and the initial results from a new ultrastable clock referred to as L10 that achieves a short-term stability of 4.5 × 10^-14/τ^1/2 and an initial measurement of no significant drift with an uncertainty of 2.4 × 10^-16/day over a two-week period.