Toward microscopy of a high filling optical lattice of polar molecules

Strongly correlated 2D ensembles of bosonic polar molecules are expected to realize a variety of interesting phases, from quantum spin liquids to extended Bose-Hubbard models. The development of a quantum gas microscope for NaRb molecules has already enabled the study of site-resolved correlations in dipolar spin-exchange Hamiltonians [1]. However, the maximum achieved lattice filling fraction in that study was 15%, primarily limited by the imperfect preparation and overlap of Na and Rb 2D Mott insulators prior to association into molecules. Here, we present a new preparation protocol for the molecular quantum gas microscope. We associate the molecules from overlapped 3D Mott insulators of Na and Rb, enabling an order of magnitude increase in the number of ground state molecules compared to our previous 2D approach. We then release the molecules into a bulk optical trap at an electric field of 4.5 kV/cm, where a large collisional barrier at short range exists due to a nearby resonance between two pair rotational states. By evaporatively cooling the molecules and loading them back into a single layer of an optical lattice, we hope to probe high-filling dipolar spin and Hubbard models with single-site resolution.



[1] Christakis, L., Rosenberg, J. S., Raj, R., Chi, S., Morningstar, A., Huse, D. A., Yan, Z. Z., & Bakr, W. S., Probing site-resolved correlations in a spin system of ultracold molecules. Nature 614, 64–69 (2023).