  This paper proposes two new full-duplex quantum communication protocols to
exchange classical or quantum information between two remote parties
simultaneously without transferring a physical particle over the quantum
channel. The first protocol, called quantum duplex coding, enables to exchange
of a classical bit using a preshared maximally entangled pair of qubits by
means of counterfactual disentanglement. The second protocol, called quantum
telexchanging, enables to exchange an arbitrary unknown qubit without using
preshared entanglement by means of counterfactual entanglement and
disentanglement. We demonstrate the quantum duplex coding and quantum
telexchanging by exploiting counterfactual electron-photon interaction gates
and show that these quantum duplex communication protocols form full-duplex
binary erasure channel and quantum erasure channels, respectively.
