Towards an optical Yb+ ion clock with sub – 1e-18 fractional systematic uncertainty

Optical atomic clocks based on ytterbium ions have demonstrated exceptional accuracy, enabling quantum metrological applications and precision tests of fundamental physics. We present recent advancements in our 171Yb+ clock, which achieves a fractional uncertainty of 7e-18 in 2e5 averaging time. In particular, we investigate an engineered Ramsey interrogation scheme designed to mitigate motional clock shifts, a key systematic uncertainty in trapped-ion clocks. By applying detuned drive pulses this protocol auto-cancels several motional shift contributions, leading to improved clock accuracy. In combination with a cryogenic environment, which eliminates black-body-radiation frequency shifts and reduces background gas collisions, we expect a total systematic fractional frequency uncertainty below 1e-18.