Quantum Cost of Dense Coding of Noisy and Multiple Use of Bell Channels

Dense coding is a basic protocol for quantum information transfer. We study the noisy and multi-use of quantum channels for dense coding protocols. For this purpose, we replace the standard channel, namely the EPR pair by a noisy two-qubit pure state. We construct the measurement Alice carries out to encode her message to be transferred to Bob. It turns out that the resulting states are not all orthogonal, and we propose a probability function for success transfer. We mathematically maximize the function in terms of the quantum measurements taken by Bob. We further develop the protocol to multi-use channels, and investigate the probability function for success transfer.