Counterfactuality of "counterfactual" communication

TL;DR

This paper critically examines the counterfactuality of recent quantum communication protocols, revealing they are only truly counterfactual for one bit value and discussing implications for security and interpretations.

Contribution

It provides a detailed analysis showing the limitations of current protocols' counterfactuality and explores their security aspects within the Bohmian interpretation framework.

Findings

Counterfactuality holds only for one transmitted bit value.

Probability of detecting a particle in the channel is not lower than actual passage.

Security considerations are linked to the protocols' counterfactual nature.

Abstract

The counterfactuality of the recently proposed protocols for direct quantum communication is analyzed. It is argued that the protocols can be counterfactual only for one value of the transmitted bit. The protocols achieve a reduced probability of detection of the particle in the transmission channel by increasing the number of paths in the channel. However, this probability is not lower than the probability of detecting a particle actually passing through such a multi-path channel, which was found to be surprisingly small. The relation between security and counterfactuality of the protocols is discussed. An analysis of counterfactuality of the protocols in the framework of the Bohmian interpretation is performed.