Systematic accuracy of the JILA strontium 1D optical lattice clock

We report an accuracy evaluation of our 1D strontium optical lattice clock operated in the Wannier-Stark regime. This recently constructed system relies on 10⁵ neutral fermionic strontium atoms trapped in the ground band of a shallow 1D optical lattice oriented along gravity. We perform recoil free spectroscopy of the least magnetically sensitive ¹S₀ to ³P₀ transition. A key feature of this system is in-situ imaging that allows us to resolve local frequency shifts such as the gravitational redshift [1]. Imaging also allows us to measure and correct for the density shift in real time. Ultimately, we entirely eliminate this shift by tuning atomic interactions [2]. Formed within an in-vacuum buildup cavity, the magic wavelength lattice has excellent homogeneity and repeatable control, allowing us to calibrate the lattice light fractional frequency shift to 3 x 10^-19 [3]. The largest uncorrected systematic shift is due to black body radiation. Improving the ³D₁ lifetime uncertainty, we reduce this shift uncertainty. In sum, the excellent stability and accuracy of this system opens the door to a host of new sensing regimes in relativistic geodesy, quantum measurement, and fundamental physics.

[1] Bothwell et al., Nature 602, 2022.

[2] Aeppli et al., Science Advances 8 (41), eadc9242, 2022.

[3] Kim et al., Physical Review Letters 113203, 2023.