Two microwave-shielded ultracold molecules in an optical tweezer

Microwave shielding is a widely used and highly effective technique for realizing degenerate Fermi gases and Bose–Einstein condensates (BECs) of polar molecules. The resulting shielding potentials, which cannot be accurately described by simple contact models, feature large repulsive cores that successfully suppress collisional losses. Despite significant advances in understanding the many- body physics of these systems, the behavior of just two microwave-shielded polar molecules (MSPMs) confined within a single optical tweezer remains largely unexplored. In this work, we demonstrate that the shielding potential introduces interaction-dependent energy shifts comparable to the intrinsic energy-level spacing of the tweezer. We also present promising applications for pairs of confined MSPMs, including tetramer formation at efficiencies significantly higher than current realizations. Finally, we estimate the parameters required to realize a multichannel Hubbard model using MSPMs within a realistic optical lattice setup.