Quantum gas microscopy of polar molecules*

Ultracold molecules are a promising platform for quantum simulation of spin physics due to their long-range interactions and large set of internal states. However, to understand the complex many-body states that emerge in these systems in and out of equilibrium, new experimental techniques are needed to probe molecule correlations in the strongly-interacting regime. Here we study the site-resolved dynamics of spin correlations in a gas of ultracold NaRb molecules in a 2D optical lattice. We first form NaRb Feshbach molecules in the lattice before transferring them to the ground state via STIRAP with 85% one-way efficiency. We operate at near-magic trapping conditions where we prepare long-lived superpositions of the ground and first excited rotational states. The molecules realize a 2D quantum XY model with long-range interactions. Using a site-resolved Ramsey interferometric technique, we detect oscillations in nearest- and next-nearest-neighbor correlations due to spin interactions. The correlations are measured by dissociating the molecules and detecting the corresponding Rb atoms with single-site resolution using a quantum gas microscope. The techniques presented here open new doors for probing quantum correlations in complex many-body systems of ultracold molecules.