Engineering many-body interactions in a spin-orbit-coupled Wannier-Stark optical lattice clock

We present recent experimental work towards understanding and harnessing atomic interactions within a strontium optical lattice clock [1]. Our vertically oriented, shallow, 1D optical lattice realizes partially delocalized Wannier-Stark eigenstates with superior quantum coherence [2]. On a single site, fermionic Sr atoms interact via weak p-wave interactions. Due to incommensurate lattice and clock wavelengths, spin-orbit coupling allows atoms in neighboring sites to interact via the s-wave channel. Balancing these collisional shifts, we can operate our optical lattice clock with a far higher on-site density while realizing a negligible density shift. Interactions are enhanced by addressing a site-changing Wannier-Stark transition. With the s-wave channel effectively opened to on-site interactions, the collisional shift is far greater in magnitude. We utilize this technique along with in situ imaging to observe a dynamical phase transition between dynamical ferromagnetic and paramagnetic states. 

[1] A Aeppli, A Chu, et al. "Hamiltonian engineering of spin-orbit coupled fermions in a Wannier-Stark optical lattice clock." arXiv preprint arXiv:2201.05909 (2022).

[2] Bothwell, Tobias, et al. "Resolving the gravitational redshift within a millimeter atomic sample." arXiv preprint arXiv:2109.12238 (2021);  Nature, in press (2022).