Split, but still attached

Recent years have witnessed the beginning of the second quantum revolution, in which an impressive degree of control over quantum systems has led to several applications in quantum communication, computation, and sensing, along with new host materials reaching commercial success. A key driver behind many of these applications is entanglement, a form of correlation that can develop between quantum systems that is stronger than any type of correlation that can exist between the macroscopic systems we deal with in our everyday life. The creation, manipulation, storage, and detection of entanglement have posed some of the biggest challenges to quantum physicists. On pages 409, 413, and 416 of this issue, Fadel et al. (1), Kunkel et al. (2), and Lange et al. (3), respectively, describe three independent experiments in which entanglement is observed in a system composed of thousands of ultracold atoms. More importantly, the entanglement is observed between atoms occupying different spatial regions, which paves the way to new applications of these systems.Peer Reviewe