  Intuition from our everyday lives gives rise to the belief that information
exchanged between remote parties is carried by physical particles.
Surprisingly, in a recent theoretical study [Salih H, Li ZH, Al-Amri M, Zubairy
MS (2013) Phys Rev Lett 110:170502], quantum mechanics was found to allow for
communication, even without the actual transmission of physical particles. From
the viewpoint of communication, this mystery stems from a (nonintuitive)
fundamental concept in quantum mechanics wave-particle duality. All particles
can be described fully by wave functions. To determine whether light appears in
a channel, one refers to the amplitude of its wave function. However, in
counterfactual communication, information is carried by the phase part of the
wave function. Using a single-photon source, we experimentally demonstrate the
counterfactual communication and successfully transfer a monochrome bitmap from
one location to another by using a nested version of the quantum Zeno effect.
