  We report an experimental realization of a modified counterfactual
communication protocol that eliminates the dominant environmental trace left by
photons passing through the transmission channel. Compared to Wheeler's
criterion for inferring past particle paths, as used in prior protocols, our
trace criterion provide stronger support for the claim of the counterfactuality
of the communication. We verify the lack of trace left by transmitted photons
via tagging the propagation arms of an interferometric device by distinct
frequency-shifts and finding that the collected photons have no frequency shift
which corresponds to the transmission channel. As a proof of principle, we
counterfactually transfer a quick response code image with sufficient fidelity
to be scanned with a cell phone.
