High-dimensional measurement-device-independent quantum secure direct communication

Quantum secure direct communication is an important communication mode of quantum communications. Its development and application are mainly limited by the channel capacity and channel loss. Here, in this paper, a high-dimensional measurement-device-independent quantum secure direct communication protocol is proposed. The quantum information is encoded on the spatial mode of the photons which enlarges the coding Hilbert space and results in the high efficiency, feasibility with existing technique, and tolerance of channel noise. Based on realistic experimental parameters, the efficiency of communications is analytically derived and numerically discussed.