Determinacy Quantum Communications In Linear Optical System

Quantum communication is a rapidly developing theory which combines quantum mechanics with information theory. A fantastic phenomenon in quantum information is entanglement, and it has been widely used in quantum communication. In this paper we propose a protocol of quantum secure direct communication and a quantum authentication scheme in linear optical system.Firstly, we introduce the basic theory of quantum information and the process of quantum communication, such as quantum logic gate, quantum dense coding, quantum teleportation and quantum swapping. In this paper, we discussed the feasibility of our system in experiment.Secondly, we propose a protocol of quantum secure direct communication scheme in linear optical system. This scheme is based on the measurement of single-photon two-qubit Bell states.Finally, we also propose a protocol of quantum authentication scheme in linear optical system. Compared with previous protocols, these two systems which we introduce in this paper ensure the security before the communication and during the communication.