Interaction-Free Effects Between Distant Atoms

  title={Interaction-Free Effects Between Distant Atoms},
  author={Yakir Aharonov and Eliahu Cohen and Avshalom C. Elitzur and Lee Smolin},
  journal={Foundations of Physics},
  pages={1 - 16}
A Gedanken experiment is presented where an excited and a ground-state atom are positioned such that, within the former’s half-life time, they exchange a photon with 50% probability. A measurement of their energy state will therefore indicate in 50% of the cases that no photon was exchanged. Yet other measurements would reveal that, by the mere possibility of exchange, the two atoms have become entangled. Consequently, the “no exchange” result, apparently precluding entanglement, is non-locally… 

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