Experimental simulation of the quantum secure direct communication using MATLAB and Simulink

Quantum secure direct communication is an important mode of quantum communication in which secret messages are securely communicated directly over a quantum channel without the requirement of symmetric key generation at first between the two nodes. Quantum secure direct communication is also a basic cryptographic primitive for constructing other quantum communication tasks, such as quantum authentication and quantum dialog. Here, we report the first detailed experimental simulation of quantum secure direct communication based on the modified version of the DL04 protocol for the phase degree of freedom and equipped with single-photon frequency coding that explicitly demonstrated block transmission. In our experiment simulator, we demonstrated both the noiseless and noisy channel versions of the protocol. In the noisy channel version, we have used 16 different aperiodic frequency channels, equivalent to a nibble of four-bit binary numbers for direct information transmission. We have explicitly demonstrated the transmission of the word ’QNu’ using block frequency at the Bob node and decoding at the Alice node. The experiment simulator firmly demonstrates the feasibility of quantum secure direct communication in the presence of noise and loss.