  In the present paper, a novel bidirectional quantum teleportation protocol is
proposed. By using entanglement swapping technique, two GHZ states are shared
as a quantum channel between Alice and Bob as legitimate users. In this scheme,
based on control-not operation, single-qubit measurement and appropriate
unitary operations, two users can simultaneously transmit a pure EPR state to
each other. While, in the previous protocols, the users can just teleport a
single-qubit state to each other via more than four-qubit state. Therefore, the
proposed scheme is economical compared with previous protocols.
