Tunable frequency shifts induced by dipole-dipole interactions in a dressed optical clock transition*

The recent observation of cooperative Lamb shifts arising from dipole-dipole interactions in a three-dimensional optical lattice clock with 87Sr [1] opens new avenues for exploring dipolar many-body quantum physics. However, the shifts observed were tiny due to the narrow linewidth (mHz) of the clock transition. To enhance this shift, we weakly dress the clock transition by coherently driving to a third level, 1P1, which features a much broader MHz level transition to 1S0 [2]. This dressing increases the effective dipole-dipole couplings of the clock transition by several orders of magnitude, making it a potential testbed to study many-body physics in a controlled environment. Using analytics and mean-field numerics, we study the dynamics under a Ramsey spectroscopy in both the large- and small-detuning regimes, obtaining the time and spatial dependence of the frequency shifts. We determine the laser configurations that lead to collective enhancement of the Lamb shift and provide insights for guiding future experiments.

[1] Hutson, R. B., Milner, W. R., Yan, L., Ye, J., & Sanner, C. (2024). Observation of millihertz-level cooperative Lamb shifts in an optical atomic clock. Science, 383(6681), 384-387.

[2] Santra, R., Arimondo, E., Ido, T., Greene, C. H., & Ye, J. (2005). High-accuracy optical clock via three-level coherence in neutral bosonic Sr 88. Physical Review Letters, 94(17), 173002.