Aharonov Yakir, Rohrlich Daniel
School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel, and Department of Physics, Chapman University, Orange, California 92866, USA.
Department of Physics, Ben-Gurion University of the Negev, Beersheba 84105, Israel.
Phys Rev Lett. 2020 Dec 31;125(26):260401. doi: 10.1103/PhysRevLett.125.260401.
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 2ℏ, either 0 or ℏ, thus precisely accounting for the one bit of information he sends her. We previously [2] obtained this result using weak values of L_{z} mod ℏ; here we do not use weak values.
