Three approaches for analyzing the counterfactuality of counterfactual protocols

Alon Wander, Eliahu Cohen

Research output: Contribution to journalArticlepeer-review


Counterfactual communication protocols are analyzed using three approaches: a classical argument, the weak trace criterion, and the Fisher information criterion. It is argued that the classical analysis leads to contradiction and should therefore be abandoned. The weak trace and Fisher information criteria are shown to agree about the degree of counterfactuality of communication protocols involving postselection. It is argued that postselection is a necessary ingredient of counterfactual communication protocols. Coherent interaction experiments, as well as a recently introduced modification of counterfactual communication setups which eliminates the weak trace, are discussed.

Original languageEnglish
Article number012610
JournalPhysical Review A
Issue number1
StatePublished - Jul 2021

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics


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