Miniature trapped-ion frequency standard with 171Yb+

We describe the development and frequency instability measurements of a highly miniaturized, buffer gas cooled, trapped-ion atomic clock. The clock utilizes the 12.6 GHz hyperfine transition of the ¹⁷¹Yb⁺ ion. A custom-built 3 cm³ vacuum package containing the ion trap is integrated with other key elements of the atomic frequency standard, including a photo multiplier tube, miniaturized laser sources at 369 nm and 935 nm, a local oscillator, and control electronics. With the clock physics package assembled on a 10 cm × 15 cm breadboard, the long-term fractional frequency instability was measured to be 6 × 10^-14 at 25 days of integration. Later, the clock physics package was further miniaturized, and the frequency instability was measured to be 2 × 10^-11/τ^1/2 at integration times up to 10,000 s.