A Portable Microwave Clock Using Laser-Cooled Trapped ¹⁷¹Yb+Ions

A portable microwave clock incorporating laser-cooling of ¹⁷¹ Yb ⁺ promises to bring significantly improved performance compared to existing thermal commercial devices. We report on progress in the development of a compact microwave frequency standard designed to fit in a 19-inch rack enclosure that comprises laser, electronics and physics package subsystems. Recent results in which a local oscillator was disciplined by laser-cooled trapped ¹⁷¹ Yb ⁺ ions are presented. Preliminary measurements have demonstrated a fractional frequency instability of 1 × 10 ^-13 at 10,000 s. Potential applications include telecommunications and financial operations time reference systems as well as navigation system integrity.