Improved Timekeeping Using Advanced Trapped-Ion Clocks

摘要

Timekeeping requires practical continuously operating frequency standards with exceptional long-term stability. JPL mercury linear ion trap standards (LITS) operate continuously with short-term stability to 2.0 x 10(exp -14) and long-term stability limited by remaining sensitivity to the second- order Doppler shift, which varies with ion number fluctuations. In this paper, we report measurements in a 12-pole trap showing a greater than twenty-fold sensitivity reduction to all parameters affecting the Second-Order Doppler Shift. This advance should further improve practical ground-based ion standard stability to the 1 x 10(exp -16) level and allow significant engineering simplifications enabling small high performance flight standards.