In this letter, a multi-user controlled bidirectional quantum secure direct communication network protocol is suggested based on classical exclusive-or operation and quantum entanglement. In this protocol, four users can securely exchange their secret massages two by two, under the permission of a controller. The quantum channel is only used for sharing the qubits, and no encoded photons are transmitted via the quantum channel. This protocol is unconditionally secure and has higher efficiency than the previous ones.
['Fahimeh Zarmehi', 'Monireh Houshmand']
Controlled Bidirectional Quantum Secure Direct Communication Network Using Classical XOR Operation and Quantum Entanglement