A Feshbach resonance in collisions between triplet ground-state molecules
A Feshbach resonance in collisions between triplet ground-state molecules
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DOI：
10.1038/s41586-022-05635-8
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发表时间：
2022-08
期刊：
影响因子：
64.8
通讯作者：
Juliana J. Park;Yu-Kun Lu;A. Jamison;T. Tscherbul;W. Ketterle
中科院分区：
文献类型：
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作者：
Juliana J. Park;Yu-Kun Lu;A. Jamison;T. Tscherbul;W. Ketterle
碰撞共振是重要的工具，已被用于修改超冷气体中的相互作用、在量子模拟中实现以前未知的哈密顿量、从原子气体创建分子以及控制化学反应。到目前为止，已经在原子与原子碰撞、原子与分子碰撞、以及束缚非常弱的 Feshbach 分子之间的碰撞中观察到了这种共振。由于可能存在高态密度和/或共振复合物的快速衰减，超冷基态分子是否存在这种共振一直存在争议。在这里，我们报告了两个三重基态 NaLi 分子之间碰撞中非常明显且狭窄的 (25 mG) Feshbach 共振。这种分子费什巴赫共振有两个特点。首先，由于强化学反应性，碰撞损失率比背景损失率提高了两个数量级以上，背景损失率在纵波普适值处饱和。其次，共振位于两个开放通道几乎退化的磁场中。这意味着中间复合物主要衰变到第二个开放通道。我们使用类似于法布里-珀罗腔的耦合模式模型来描述谐振损耗特征。我们的观察结果为即使在没有反应势垒的系统中也存在长寿命相干中间配合物的存在提供了强有力的证据，并开辟了化学反应相干控制的可能性。
Collisional resonances are important tools that have been used to modify interactions in ultracold gases, for realizing previously unknown Hamiltonians in quantum simulations, for creating molecules from atomic gases and for controlling chemical reactions. So far, such resonances have been observed for atom–atom collisions, atom–molecule collisions, , , –and collisions between Feshbach molecules, which are very weakly bound, –. Whether such resonances exist for ultracold ground-state molecules has been debated owing to the possibly high density of states and/or rapid decay of the resonant complex, , , –. Here we report a very pronounced and narrow (25 mG) Feshbach resonance in collisions between two triplet ground-state NaLi molecules. This molecular Feshbach resonance has two special characteristics. First, the collisional loss rate is enhanced by more than two orders of magnitude above the background loss rate, which is saturated at thep-wave universal value, owing to strong chemical reactivity. Second, the resonance is located at a magnetic field where two open channels become nearly degenerate. This implies that the intermediate complex predominantly decays to the second open channel. We describe the resonant loss feature using a model with coupled modes that is analogous to a Fabry–Pérot cavity. Our observations provide strong evidence for the existence of long-lived coherent intermediate complexes even in systems without reaction barriers and open up the possibility of coherent control of chemical reactions.