The Role of Localizable Concurrence in Quantum Teleportation Protocols

Abstract: Teleporting an unknown qubit state is a paradigmatic quantum information processing task revealing the advantage of quantum communication protocols over their classical counterpart. For a teleportation protocol using a Bell state as quantum channel, the resource has been identified to be the concurrence. However, for mixed multi-partite states the lack of computable entanglement measures has made the identification of the quantum resource responsible for this advantage more challenging. Here, by building on previous results showing that localizable concurrence is the necessary resource for controlled quantum teleportation, we show that any teleportation protocol using an arbitrary multi-partite state, that includes a Bell measurement, requires a non-vanishing localizable concurrence between two of its parties in order to perform better than the classical protocol. By first analyzing the GHZ channel and GHZ measurement teleportation protocol, in the presence of GHZ-symmetric-preserving noise, we compare different multi-partite entanglement measures with the fidelity of teleportation, and we find that the protocol performs better than the classical protocol when all multi-partite entanglement measures vanish, except for the localizable concurrence. Finally, we extend our proof to an arbitrary teleportation protocol with an arbitrary multi-partite entangled channel.