Enhancing optical clock stability via decoupling laser frequency noise and systematic effects

Optical lattice clocks demonstrate advantages in metrology and frontier physics because of their high stability. Here, we present approaches to enhancing the stability by decoupling the noise related to the short-term and long-term stability. For the short-term stability, we optimize the clock laser by decoupling the frequency noise, and optimize each noise contribution individually until it is below the thermal noise limit. For the long-term stability, we introduce a method to decouple the instability caused by systematic effects. Having identified that the collision frequency shift was the main limiting factor in our systems, we thus optimized the atom number fluctuations in optical lattices. Through targeted optimization, we achieve a synchronous comparison of two clocks with an average stability of 3.2 × 10⁻¹⁶=p √τ and a long-term stability of 2.4 × 10⁻¹⁸ at 8000 s. This work provides an analytical framework for enhancing optical clock stability.