Prior entanglement between senders enables perfect quantum network coding with modification

摘要

We find a protocol transmitting two quantum states crossly in the butterflynetwork only with prior entanglement between two senders. This protocolrequires only one qubit transmission or two classical bits transmission in eachchannel in the butterfly network. It is also proved that it is impossiblewithout prior entanglement. More precisely, an upper bound of average fidelityis given in the butterfly network when prior entanglement is not allowed.