Quantum Secure Direct Communication Network

In this paper, we propose a quantum secure direct communication (QSDC) network architecture based on EPR pairs. This network architecture can implement quantum secure direct communication with intermediate nodes. In this QSDC network architecture, there are several server nodes which are connected with quantum channels and classical channels. An authentication server is used to identify users. The server nodes can generate EPR pairs and deliver the qubits through the quantum channel to the other node. We also propose a QSDC protocol. The users request to share constant number of EPR pairs with the nearest server nodes. The server nodes teleport the sender's qubits to the receiver. The sender can transmit arbitrary number of qubits to the receiver.