Generalized controlled dense coding with maximally entangled multiqubit states

Controlled dense coding which uses different five-qubit entangled systems is described in this article. Using a criterion based on quantum-statistical correlations to define the extent of entanglement, five-qubit states are shown to have genuine entanglement. Different schemes which are easily implementable experimentally for a receiver to decode the message from a sender are described. The importance of representation of a quantum channel and distribution of qubits in a communication protocol are emphasized. It is observed that when a controller is involved it is desirable that measurement results are transmitted to the receiver and not to the sender for experimental convenience. In addition, a controlled dense coding protocol for average information transfer is given for arbitrary (2N + 1)-qubit entangled systems, using the above schemes. © 2010 World Scientific Publishing Company.