An Active Ion Optical Clock

We propose a scheme for an active ion optical clock with a detailed description of the pumping method, lasing states, output power, linewidth and light shift. Considering ¹⁷¹Yb⁺ ions in a Paul trap, we propose utilizing a Fabry–Perot resonator to realize the lasing of active optical frequency standards. The quantum-limited linewidth of an active ¹⁷¹Yb⁺ ion optical clock is narrower than 1 mHz. Based on the mechanism and the advantages of an active optical clock at the ion optical clock transition frequency, this new laser light source as a stable local oscillator will be beneficial to the single-ion optical clock, which currently is one of the most accurate clocks.