What Is Nonlocal in Counterfactual Quantum Communication?

  title={What Is Nonlocal in Counterfactual Quantum Communication?},
  author={Yakir Aharonov and Daniel Rohrlich},
  journal={Physical review letters},
  volume={125 26},
We revisit the "counterfactual quantum communication" of Salih et al. [1], who claim that an observer "Bob" can send one bit of information to a second observer "Alice" without any physical particle traveling between them. We show that a locally conserved, massless current-specifically, a current of modular angular momentum, L_{z} mod 2ℏ-carries the one bit of information. We integrate the flux of L_{z} mod 2ℏ from Bob to Alice and show that it equals one of the two eigenvalues of L_{z} mod 2… 

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our paper, and all the referees for their clear insight into what we had left unclear. Y. A. thanks the Israel Science Foundation (Grant No. 1311/14), the ICORE Excellence Center