We report the first measurement of ground state diamagnetism of isolated neutral atoms in an atomic beam. We realize this using magnetic deflection of fringes in a long baseline matter-wave interferometer. The observed diamagnetic susceptibilities of $-5.8\pm 0.2\pm 0.3\times {10}^{-9}{m}^3/kg$ for barium and $-6.9\pm 0.3\pm 0.6\times {10}^{-9}{m}^3/kg$ for strontium are in good agreement with the theory values, and correspond to a measured force on the order of ${10}^{-26}$ N. The high force sensitivity also allowed us to observe the isotope dependence of the interference visibility due to the nuclear permanent magnetic moment, thereby demonstrating a new method for neutral isotope selection. The universality of the technique allows the magnetism of a wide range of atoms and molecules to be studied in the gas phase.

中文翻译：

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量子辅助磁性反磁的测量

我们报告了原子束中孤立的中性原子基态反磁性的首次测量。我们通过在长基线物质波干涉仪中使用条纹的磁偏转来实现这一点。观察到的抗磁化率$-5.8\pm 0.2\pm 0.3\times {10}^{-9}{米}^3/ķG$ 用于钡和 $-6.9\pm 0.3\pm 0.6\times {10}^{-9}{米}^3/ķG$ 锶与理论值非常吻合，并且对应于一个测得的力 ${10}^{-26}$N.高力敏感度还使我们能够观察到由于核永久磁矩而引起的干扰能见度的同位素依赖性，从而证明了一种选择中性同位素的新方法。该技术的普遍性允许在气相中研究各种原子和分子的磁性。