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Updated: Nov 21, 2025

Generation and Coherent Control of Pulsed Quantum Frequency Combs
Published on: June 8, 2018
What Is Nonlocal in Counterfactual Quantum Communication?
Yakir Aharonov1, Daniel Rohrlich2
1School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel, and Department of Physics, Chapman University, Orange, California 92866, USA.
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, 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.
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