Reply to "Counterfactual communication not achieved yet -- A Comment on Salih et al. (2022)"

TL;DR

This paper defends the authors' previous claim that counterfactual communication is possible with post-selected particles, refuting a comment that challenged their theoretical and experimental evidence based on specific criteria.

Contribution

The authors clarify and reaffirm that their protocol enables counterfactual communication without particle exchange, addressing and correcting misconceptions in the comment.

Findings

Counterfactual communication is possible for post-selected particles.

The protocol allows high-accuracy binary message transmission.

Experimental evidence supports the theoretical claims.

Abstract

In his Comment on our recent paper ``The laws of physics do not prohibit counterfactual communication'', \textit{npj Quantum Information} (2022) 8:60, Popescu argues that the claims of the paper are invalid. Here, we refute his argument, showing that it is based on ignoring the specifics of what we set out to prove (that counterfactual communication is possible \emph{for post-selected particles}, and more specifically in these cases is not prohibited by the weak trace or consistent histories criteria for particle path), followed by an unwarranted simplification of the protocol. Moreover, the Comment's excursion into interpretation is misplaced. Our communication protocol is a precisely defined one that allows two remote parties, albeit rarely, to communicate an arbitrarily long binary message, with arbitrarily high accuracy. This is not a matter of interpretation -- as the concrete example given in our paper in question illustrates. As for our overarching claim that no particles are exchanged in the course of this communication, we have already demonstrated this both theoretically and experimentally, in the postselected case we consider, as per the weak trace and consistent histories criteria for path of a quantum particle.