Entanglement swapping between photons that have never coexisted

E. Megidish*, A. Halevy, T. Shacham, T. Dvir, L. Dovrat, H. S. Eisenberg

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

83 Scopus citations

Abstract

The role of the timing and order of quantum measurements is not just a fundamental question of quantum mechanics, but also a puzzling one. Any part of a quantum system that has finished evolving can be measured immediately or saved for later, without affecting the final results, regardless of the continued evolution of the rest of the system. In addition, the nonlocality of quantum mechanics, as manifested by entanglement, does not apply only to particles with spacelike separation, but also to particles with timelike separation. In order to demonstrate these principles, we generated and fully characterized an entangled pair of photons that have never coexisted. Using entanglement swapping between two temporally separated photon pairs, we entangle one photon from the first pair with another photon from the second pair. The first photon was detected even before the other was created. The observed two-photon state demonstrates that entanglement can be shared between timelike separated quantum systems.

Original languageAmerican English
Article number210403
JournalPhysical Review Letters
Volume110
Issue number21
DOIs
StatePublished - 22 May 2013

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