We present an explicit protocol ${\mathcal{E}}_0$ for faithfully teleporting an arbitrary two-qubit state via a genuine four-qubit entangled state. By construction, our four-partite state is not reducible to a pair of Bell states. Its properties are compared and contrasted with those of the four-party Greenberger-Horne-Zeilinger and $W$ states. We also give a dense coding scheme ${\mathcal{D}}_0$ involving our state as a shared resource of entanglement. Both ${\mathcal{D}}_0$ and ${\mathcal{E}}_0$ indicate that our four-qubit state is a likely candidate for the genuine four-partite analogue to a Bell state.

• Received 12 October 2005

DOI:https://doi.org/10.1103/PhysRevLett.96.060502