English

What is nonlocal in counterfactual quantum communication?

Quantum Physics 2021-02-03 v1

Abstract

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, LzL_z mod 2\hbar - carries the one bit of information. We integrate the flux of LzL_z mod 2\hbar from Bob to Alice and show that it equals one of the two eigenvalues of LzL_z mod 2\hbar, either 0 or \hbar, thus precisely accounting for the one bit of information he sends her. We previously [2] obtained this result using weak values of LzL_z mod 2\hbar; here we do not use weak values.

Cite

@article{arxiv.2011.11667,
  title  = {What is nonlocal in counterfactual quantum communication?},
  author = {Yakir Aharonov and Daniel Rohrlich},
  journal= {arXiv preprint arXiv:2011.11667},
  year   = {2021}
}

Comments

Physical Review Letters, in press

R2 v1 2026-06-23T20:27:24.004Z