  Quantum self-interference enables the counterfactual transmission of
information, whereby the transmitted bits involve no particles traveling
through the channel. In this work, we show how counterfactuality can be
realized even when the self interference is replaced by interference between
identical particles. Interestingly, the facet of indistinguishability called
forth here is associated with first-order coherence, and is different from the
usual notion of indistinguishability associated with the (anti-)commutation
relations of mode operators. From an experimental perspective, the simplest
implementation of the proposed idea can be realized by slight modifications to
existing protocols for differential-phase-shift quantum key distribution or
interaction-free measurement.
