Quantum teleportation with additional a priori information about the input state achieves higher fidelity than teleportation of a completely unknown state. However, perfect teleporation of two nonorthogonal input states requires the same amount of entanglement as perfect teleportation of an unknown state, namely one ebit. We analyze how well two-state teleportation can be achieved using every degree of pure-state entanglement. We find the highest fidelity of “teleportation” that can be achieved with only classical communication but no shared entanglement. A two-state telecloning scheme is constructed.

• Received 7 October 1999

DOI:https://doi.org/10.1103/PhysRevA.61.062306