Brief get-togethers between NaK and K Cooling molecules to nanokelvin temperatures places them under the tightest quantum mechanical constraints. Studies in this intriguing regime have been limited to diatomics: Two cold atoms can be lured together into weakly associated Feshbach resonances, which lasers can then shift into a more stable molecular state. Yang et al. now report the observation of triatomic Feshbach resonances in ultracold collisions between potassium (K) atoms and sodium potassium (NaK) diatomics. The findings potentially set the stage for the preparation and study of ultracold triatomic molecules. Science, this issue p. 261 Transient weakly associated complexes between a K atom and a NaK molecule have been observed at ultracold temperatures. Resonances in ultracold collisions involving heavy molecules are difficult to simulate theoretically and have proven challenging to detect. Here we report the observation of magnetically tunable Feshbach resonances in ultracold collisions between potassium-40 (40K) atoms and sodium-23–potassium-40 (23Na40K) molecules in the rovibrational ground state. We prepare the atoms and molecules in various hyperfine levels of their ground states and observe the loss of molecules as a function of the magnetic field. The atom-molecule Feshbach resonances are identified by observing an enhancement of the loss. We have observed 11 resonances in the magnetic field range of 43 to 120 gauss. The observed atom-molecule Feshbach resonances at ultralow temperatures probe the three-body potential energy surface with exceptional resolution and will help to improve understanding of ultracold collisions.

中文翻译：

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在超冷 23Na40K + 40K 碰撞中观察磁可调 Feshbach 共振

NaK 和 K 之间的简短聚会将分子冷却到纳开尔文温度，使它们处于最严格的量子力学约束之下。在这个有趣的机制中的研究仅限于双原子：两个冷原子可以一起被引诱到弱关联的 Feshbach 共振中，然后激光可以转变为更稳定的分子状态。杨等人。现在报告在钾 (K) 原子和钠钾 (NaK) 双原子之间的超冷碰撞中观察到三原子 Feshbach 共振。这些发现可能为超冷三原子分子的制备和研究奠定了基础。科学，这个问题 p。261 已经在超低温下观察到 K 原子和 NaK 分子之间的瞬态弱结合复合物。涉及重分子的超冷碰撞中的共振很难在理论上进行模拟，并且已证明难以检测。在这里，我们报告了在旋转振动基态下钾 40 (40K) 原子和钠 23-钾 40 (23Na40K) 分子之间的超冷碰撞中磁可调 Feshbach 共振的观察结果。我们准备原子和分子在其基态的各种超精细水平，并观察分子的损失作为磁场的函数。原子-分子 Feshbach 共振是通过观察损失的增强来识别的。我们在 43 到 120 高斯的磁场范围内观察到了 11 次共振。