In 1935, Einstein, Podolsky, and Rosen (EPR) conceived a gedanken experiment which became a cornerstone of quantum technology and still challenges our understanding of reality and locality today. While the experiment has been realized with small quantum systems, a demonstration of the EPR paradox with massive many-particle systems remains an important challenge, as such systems are particularly closely tied to the concept of local realism in our everyday experience and may serve as probes for new physics at the quantum-to-classical transition. In this work we report an EPR experiment with two spatially separated Bose-Einstein condensates, each containing about 700 rubidium atoms. Entanglement between the condensates results in strong correlations of their collective spins, allowing us to demonstrate the EPR paradox between them. Our results represent the first observation of the EPR paradox with spatially separated, massive many-particle systems. They show that the conflict between quantum mechanics and local realism does not disappear as the system size increases to more than a thousand massive particles. Furthermore, EPR entanglement in conjunction with individual manipulation of the two condensates on the quantum level, as we demonstrate here, constitutes an important resource for quantum metrology and information processing with many-particle systems.

中文翻译：

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Einstein-Podolsky-Rosen 用两种玻色-爱因斯坦凝聚体进行实验

1935 年，爱因斯坦、波多尔斯基和罗森 (EPR) 构想了一个 gedanken 实验，该实验成为量子技术的基石，至今仍在挑战我们对现实和局部性的理解。虽然该实验已通过小型量子系统实现，但用大规模多粒子系统证明 EPR 悖论仍然是一个重要挑战，因为此类系统与我们日常经验中的局部现实主义概念特别密切相关，可以作为探测器用于从量子到经典过渡的新物理学。在这项工作中，我们报告了一个 EPR 实验，其中包含两个空间分离的玻色-爱因斯坦凝聚体，每个凝聚体包含大约 700 个铷原子。凝聚物之间的纠缠导致它们集体自旋的强相关性，使我们能够证明它们之间的 EPR 悖论。我们的结果代表了对空间分离的大质量多粒子系统的 EPR 悖论的首次观察。他们表明，随着系统大小增加到超过一千个大质量粒子，量子力学与局域实在论之间的冲突并没有消失。此外，正如我们在此展示的那样，EPR 纠缠与在量子水平上对两种凝聚体的单独操纵相结合，构成了多粒子系统的量子计量学和信息处理的重要资源。