Towards Record High Stability and Accuracy In A 1D Strontium Optical Lattice Clock

With recent demonstrations of record stability [1] and excellent accuracy [2], strontium is a promising candidate for a broad range of applications including the redefinition of the SI second. We report on the progress of our recently rebuilt 1D strontium optical lattice clock. Our new clock incorporates an in-vacuum build-up cavity for a vertically oriented lattice allowing loading of millimeter sized samples at very low lattice depths. Self-synchronous imaging permits rapid frequency comparison between different regions of the elongated sample, probing frequency homogeneity and atomic coherence. We demonstrate improved stability surpassing that of Ref. [1] and atom-atom coherence times comparable with recent work in optical tweezers [3]. Our room-temperature design has excellent thermal homogeneity and stability, passive and active suppression of DC Stark shifts, and highly reproducible trapping potentials. This system is well positioned for characterization of systematic frequency shifts at the 19th digit corresponding to geodesy at the mm level.

[1] Oelker, E., et al. "Demonstration of 4.8×10⁻¹⁷ stability at 1 s for two independent optical clocks." Nature Photonics 13.10 (2019): 714-719.

[2] Bothwell, Tobias, et al. "JILA SrI optical lattice clock with uncertainty of." Metrologia 56.6 (2019): 065004.

[3] Young, Aaron W., et al. "Half-minute-scale atomic coherence and high relative stability in a tweezer clock." Nature 588.7838 (2020): 408-413.