Tripartite non-maximally-entangled mixed states as a resource for optimally controlled quantum teleportation fidelity

Abstract

Three-qubit mixed states are used as a channel for controlled quantum teleportation (CQT) of single-qubit states. The connection between different channel parameters to achieve maximum controlled teleportation fidelity is investigated. We show that for a given multipartite entanglement and mixedness a class of non-maximally-entangled mixed $X$ states ($X$-NMEMS) achieves optimum controlled quantum teleportation fidelity; interestingly a class of maximally entangled mixed $X$ states ($X$-MEMS) fails to do so. This demonstrates, for a given spectrum and mixedness, that $X$-MEMS are not sufficient to attain optimum controlled quantum teleportation fidelity, which is in contradiction with the traditional quantum teleportation of single qubits. In addition, we show that biseparable $X$-NMEMS, for a certain range of mixedness, are useful as a resource to attain high controlled quantum teleportation fidelity, which essentially lowers the requirements of quantum channels for CQT.