Optical Clocks Based on Quantum Emitters

In this report, we discuss the new feature of optical clocks based on quantum emitters, including clock operating above threshold, which is a laser essentially used as an active optical clock, and clock operating under threshold. Comparing with the active microwave clock, hydrogen maser, excellent performance of optical clock based on quantum emitter is expected. Comparison between configurations of atomic beam and lattice trapped atoms is analyzed. Moreover, we also present the discussion on the possibility of Ramsey laser, a laser operating at the configuration of Ramsey separated oscillating fields