Quantum enhanced optical atomic clock*

High bandwidth, high stability clocks offer unique chances to study fundamental physics beyond simple metrology. Optical atomic clocks which are primarily limited by the quantum projection noise have reached stability beyond 10^-18. However, it took hours to average noise down to achieve such performance. Quantum state engineering on the other hand allows one to redistribute quantum noise. By combing the techniques of these two fields, an optical lattice clock with special quantum entangled state can reach the same stability at a much faster pace. With cavity feedback squeezing and coherent optical state transfer, we demonstrated entanglement on optical clock transition in ¹⁷¹Yb . We achieve a metrological gain of 4.4 dB beyond standard quantum limit. Recently, we are working on optimize our local oscillator laser locking to the a stable reference cavity. With a better performance of optical clock laser, we would be able to demonstrate a full operational quantum enhanced optical atomic clock.