Bonding's outer limit In a Rydberg state, an atom has been very nearly, but not quite, ionized. This puts the electron relatively far from the nucleus, and two atoms in such a state can thus form a rather long-range bond. Hollerith et al. observed this phenomenon in fine detail by exciting pairs of ultracold rubidium atoms along the diagonal of an optical lattice. The authors resolved the vibrational state structure spectroscopically and showed that the Rydberg dimers manifested bond lengths exceeding 700 nanometers. Science, this issue p. 664 Weakly bound molecules with bond lengths approaching a micrometer were characterized at high resolution in an optical lattice. The subnanoscale size of typical diatomic molecules hinders direct optical access to their constituents. Rydberg macrodimers—bound states of two highly excited Rydberg atoms—feature interatomic distances easily exceeding optical wavelengths. We report the direct microscopic observation and detailed characterization of such molecules in a gas of ultracold rubidium atoms in an optical lattice. The bond length of about 0.7 micrometers, comparable to the size of small bacteria, matches the diagonal distance of the lattice. By exciting pairs in the initial two-dimensional atom array, we resolved more than 50 vibrational resonances. Using our spatially resolved detection, we observed the macrodimers by correlated atom loss and demonstrated control of the molecular alignment by the choice of the vibrational state. Our results allow for rigorous testing of Rydberg interaction potentials and highlight the potential of quantum gas microscopy for molecular physics.

中文翻译：

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里德堡大二聚体的量子气体显微镜

键合的外极限 在里德堡态中，原子已经非常接近但不完全电离。这使电子离原子核相对较远，因此处于这种状态的两个原子可以形成相当长的键。霍勒瑞思等人。通过沿着光学晶格的对角线激发成对的超冷铷原子，详细观察了这种现象。作者通过光谱解析了振动状态结构，并表明里德堡二聚体的键长超过 700 纳米。科学，这个问题 p。664 个键长接近微米的弱结合分子在光学晶格中以高分辨率进行表征。典型双原子分子的亚纳米级尺寸阻碍了对其成分的直接光学访问。里德堡大二聚体——两个高度激发的里德堡原子的束缚态——具有很容易超过光波长的原子间距离。我们报告了这种分子在光学晶格中超冷铷原子气体中的直接显微观察和详细表征。约 0.7 微米的键长与小细菌的大小相当，与晶格的对角线距离相匹配。通过在初始二维原子阵列中激发对，我们解决了 50 多个振动共振。使用我们的空间分辨检测，我们通过相关的原子损失观察了大二聚体，并通过选择振动状态证明了对分子排列的控制。