Two-photon pathway to the rovibrational ground state of ²³Na⁴¹K molecules

Ultracold polar molecules provide a novel platform for quantum simulation of many-body systems, combining rich internal structure with strong, long-range dipole–dipole interactions and flexible control. Recent advances in collisional shielding techniques enable long-lived bosonic samples of dipolar molecules, opening access to strongly correlated phases of matter such as exotic superfluids and quantum crystals. In this talk, we report progress toward identifying a two-photon pathway that connects weakly bound bosonic ²³Na⁴¹K Feshbach molecules to the rovibrational ground state. Starting from photoassociation spectroscopy in an ultracold ²³Na-⁴¹K atomic mixture, we resolve ~20 vibrational levels of the electronically excited c³Σ⁺ state. Using high-resolution spectroscopy of the rotational structure, we identify an intermediate level with pronounced singlet-triplet mixing, consistent with strong perturbation by nearby B¹Π character via spin-orbit coupling. This mixed level provides a promising candidate intermediate state for two-photon transfer to the absolute ground state X¹Σ⁺|v=0, J=0〉.