Scattering resonances are an essential tool for controlling the interactions of ultracold atoms and molecules. However, conventional Feshbach scattering resonances¹, which have been extensively studied in various platforms^{1,2,3,4,5,6,7}, are not expected to exist in most ultracold polar molecules because of the fast loss that occurs when two molecules approach at a close distance^8,9,10. Here we demonstrate a new type of scattering resonance that is universal for a wide range of polar molecules. The so-called field-linked resonances^11,12,13,14 occur in the scattering of microwave-dressed molecules because of stable macroscopic tetramer states in the intermolecular potential. We identify two resonances between ultracold ground-state sodium–potassium molecules and use the microwave frequencies and polarizations to tune the inelastic collision rate by three orders of magnitude, from the unitary limit to well below the universal regime. The field-linked resonance provides a tuning knob to independently control the elastic contact interaction and the dipole–dipole interaction, which we observe as a modification in the thermalization rate. Our result provides a general strategy for resonant scattering between ultracold polar molecules, which paves the way for realizing dipolar superfluids¹⁵ and molecular supersolids¹⁶, as well as assembling ultracold polyatomic molecules.

散射共振是控制超冷原子和分子相互作用的重要工具。然而，传统的 Feshbach 散射共振¹已在各种平台^{1,2,3,4,5,6,7}中进行了广泛研究，预计不会存在于大多数超冷极性分子中，因为当两个分子发生时会发生快速损失近距离接近^8,9,10。在这里，我们展示了一种新型的散射共振，它适用于各种极性分子。所谓的场联共振^11,12,13,14由于分子间势中稳定的宏观四聚体状态，发生在微波修饰分子的散射中。我们确定了超冷基态钠钾分子之间的两个共振，并使用微波频率和极化将非弹性碰撞率调整了三个数量级，从单一极限到远低于普遍状态。场联共振提供了一个调谐旋钮来独立控制弹性接触相互作用和偶极-偶极相互作用，我们将其观察为热化率的变化。^{我们的结果为超冷极性分子之间的共振散射提供了一种通用策略，为实现偶极超流体15}和分子超固体¹⁶铺平了道路，以及组装超冷多原子分子。