Quantum secure direct communication based on quantum dense coding using a class of W-states

According to the characteristics of a class of three-particle W-states and the quantum dense coding, a new quantum secure direct communication scheme is presented. All particles, which are transmitted, are used to encode secret information except for the particles for testing security, which can greatly improve the communication efficiency. In order to ensure the security of the scheme, the channel is tested two times using the entanglement correlation between particles of W-states in particle distribution phase. It can improve the detection rate for eavesdropper and the reduce information leakage by inserting decoy photons into particles and rearranging the order of particles in information transfer phase. Security analysis shows that the scheme can ensure information transfer security and improve communication efficiency.