We entangle two photons, with the first detected even before the other is created, by using entanglement swapping between temporally-separated polarization-entangled photon pairs. This result shows the nonlocality of quantum mechanics in spacetime.
© 2012 OSA
E. Megidish, A. Halevy, T. Shacham, T. Dvir, L. Dovrat, and H. Eisenberg, "Entanglement between photons that never co-existed," in Research in Optical Sciences, OSA Technical Digest (Optical Society of America, 2012), paper QT5A.9.
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