近日，德国马克斯-普朗克量子光学研究所的Xin-Yu Luo与中国科学院理论物理研究所的石弢等人合作并取得一项新进展。经过不懈努力，他们成功生成超冷场连接的四原子分子。相关研究成果已于2024年1月31日在国际权威学术期刊《自然》上发表。
该研究团队展示了一种创新方法，通过电场连接共振在微波修饰的极性分子简并费米气体中，通过电缔合产生弱束缚的超冷多原子分子。从基态NaK分子开始，研究人员成功生成了约1.1×103个弱结合的四原子(NaK)2分子。这些分子在134(3)nK的温度下，相空间密度为0.040(3)，比之前实现的要低3000多倍。研究人员观察到四聚物在自由空间中的最长寿命为8(2)ms，在光学偶极子势阱存在下没有明显变化，表明这些四聚物是碰撞稳定的。
此外，研究人员通过微波场调制直接成像解离的四聚物，探测其波函数在动量空间中的各向异性。这项研究结果不仅展示了一种从较小的极性分子，组装弱束缚超冷多原子分子的通用工具，而且迈出了向多原子分子的玻色-爱因斯坦凝聚和从偶极Bardeen-Cooper-Schrieffer超流体，到玻色-爱因斯坦四聚物凝聚的新交叉的关键一步。此外，长寿命的场连接态为将光确定性传输到深度束缚的四聚物态提供了理想起点。
据悉，超冷多原子分子因其丰富的内部结构，为冷化学、精密测量和量子信息处理等领域提供了独特的机会。然而，与双原子分子相比，它们的复杂性增加，这给传统冷却技术的应用带来了挑战。
附：英文原文
Title: Ultracold field-linked tetratomic molecules
Author: Chen, Xing-Yan, Biswas, Shrestha, Eppelt, Sebastian, Schindewolf, Andreas, Deng, Fulin, Shi, Tao, Yi, Su, Hilker, Timon A., Bloch, Immanuel, Luo, Xin-Yu
Issue&Volume: 2024-01-31
Abstract: Ultracold polyatomic molecules offer opportunities in cold chemistry, precision measurements and quantum information processing, because of their rich internal structure. However, their increased complexity compared with diatomic molecules presents a challenge in using conventional cooling techniques. Here we demonstrate an approach to create weakly bound ultracold polyatomic molecules by electroassociation (F.D. et al., manuscript in preparation) in a degenerate Fermi gas of microwave-dressed polar molecules through a field-linked resonance. Starting from ground-state NaK molecules, we create around 1.1×103 weakly bound tetratomic (NaK)2 molecules, with a phase space density of 0.040(3) at a temperature of 134(3)nK, more than 3,000 times colder than previously realized tetratomic molecules. We observe a maximum tetramer lifetime of 8(2)ms in free space without a notable change in the presence of an optical dipole trap, indicating that these tetramers are collisionally stable. Moreover, we directly image the dissociated tetramers through microwave-field modulation to probe the anisotropy of their wavefunction in momentum space. Our result demonstrates a universal tool for assembling weakly bound ultracold polyatomic molecules from smaller polar molecules, which is a crucial step towards Bose–Einstein condensation of polyatomic molecules and towards a new crossover from a dipolar Bardeen–Cooper–Schrieffer superfluid to a Bose–Einstein condensation of tetramers. Moreover, the long-lived field-linked state provides an ideal starting point for deterministic optical transfer to deeply bound tetramer states.
DOI: 10.1038/s41586-023-06986-6
Source: https://www.nature.com/articles/s41586-023-06986-6
Nature：《自然》，创刊于1869年。隶属于施普林格·自然出版集团，最新IF：69.504
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