  We study quantum teleportation with the resource of non-orthogonal qubit
states. We first extend the standard teleportation protocol to the case of such
states. We investigate how the loss of teleportation fidelity resulting for the
use of non-orthogonal states compares to a similar loss of fidelity when noisy
or non-maximally entangled states as used as teleportation resource. Our
analysis leads to certain interesting results on the teleportation efficiency
of both pure and mixed non-orthgonal states compared to that of non-maximally
entangled and mixed states.
