Quantum teleportation via a W state -: art. no. 136

We investigate two schemes of quantum teleportation with a W state, which belongs to a different class from the Greenberger - Horne - Zeilinger class. In the first scheme, the W state is shared by three parties, one of whom, called a sender, performs a Bell measurement. It is shown that the quantum information of an unknown state is split between two parties and recovered with a certain probability. In the second scheme, a sender takes two particles of the W state and performs positive operator valued measurements. For the two schemes, we calculate the success probability and the average fidelity. We show that the average fidelity of the second scheme cannot exceed that of the first one.