Fidelity and the communication of quantum information

We compare and contrast the error probability and fidelity as measures of t he quality of the receiver's measurement strategy for a quantum communicati ons system. The error probability is a measure of the ability to retrieve c lassical information and the fidelity measures the retrieval of quantum inf ormation. We present the optimal measurement strategies for maximizing the fidelity given a source that encodes information on the symmetric qubit-sta tes.