# What Is Nonlocal in Counterfactual Quantum Communication?

@article{Aharonov2020WhatIN, title={What Is Nonlocal in Counterfactual Quantum Communication?}, author={Yakir Aharonov and Daniel Rohrlich}, journal={Physical review letters}, year={2020}, volume={125 26}, pages={ 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 2…

## 7 Citations

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### A dynamical quantum Cheshire Cat effect and implications for counterfactual communication

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A type of dynamic effect is reported that is at the core of the so called "counterfactual computation" and especially " counterfactual communication" quantum effects that have generated a lot of interest recently, and generalizes the quantum Cheshire Cat effect to dynamical settings.

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We explore how one might detect the dynamical quantum Cheshire cat proposed by Aharonov et al. We show that, in practice, we need to bias the initial state by adding/subtracting a small probability…

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A protocol for ghost imaging is given in a way that is always counterfactual—while imaging an object, no light interacts with that object, and it provides a many-fold improvement in visibility and signal-to-noise ratio over previous protocols.

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