Optimal information transmission in the non-ideal quantum dense coding of qubits

摘要

The maximum amount of classical information that can be transmitted by means of the quantum dense coding with a partially entangled pure state of qubits is obtained. It is shown that the Bell measurement is optimum even in this case. The result is compared with that obtained by the quantum dense coding with the entanglement distillation process. It is found that although the collective entanglement distillation process is not effective for the quantum teleportation, it is useful for the quantum dense coding. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 20]