Direct counterfactual quantum communication protocol beyond single photon source

TL;DR

This paper demonstrates that counterfactual quantum communication can be achieved using multiphoton sources, approaching perfect success probability, without photons traveling through the communication channel, extending previous single-photon protocols.

Contribution

It introduces a method to perform counterfactual quantum communication with multiphoton light sources, surpassing the limitations of single-photon input requirements.

Findings

Counterfactual communication with multiphoton sources approaches unity success probability.

Photon paths are non-locally controlled, enabling information transfer without photons in the channel.

A modified scheme reduces the number of interferometers needed.

Abstract

The direct counterfactual quantum communication protocol involving double chained Mach-Zehnder interferometers requires a single photon input. Here, we show that even with multiphoton light sources, including a strong coherent light source as inputs, the counterfactual communication can be achieved with success probability approaching unity in the ideal asymptotic limit. The path evolution of multiple photons is non-locally controlled. Thus, information is transmitted without any photons, or any other auxiliary information carriers, appearing in the public transmission channel. The effect is quantum since quantum measurements are essential requirement for this protocol. Furthermore, a modified scheme is proposed in which number of interferometers is reduced.