Molecular vibrational spectroscopy with 13-digit accuracy

Molecular clocks are a powerful platform in the search for new physics, including yet unknown forces and the time variation of fundamental constants. Previously, we demonstrated magic wavelength trapping of ⁸⁸Sr₂ molecules in a 1D optical lattice, enabling coherence times approaching 100 ms limited by lattice light scattering [1,2]. Here, we present a detailed analysis of the high-Q vibrational clock transition spanning the entire depth of the X¹Σ_g⁺ ground potential. We demonstrate control of systematic shifts in the molecular clock at the 10^-14 level with possibilities for further improvement, and report a measurement of the vibrational splitting with 13-digits accuracy. Additionally, we discuss current efforts toward longer clock interrogation times and larger signal-to-noise through STIRAP [3], rotational repumping, and atomic sideband cooling.

[1] S. S. Kondov et al., Nat. Phys. 15, 1118 (2019)

[2] K. H. Leung et al., Phys. Rev. Lett. 125, 153001 (2020)

[3] K. H. Leung et al., New J. Phys. 23, 115002 (2021)