Quantum Secure Direct Communication: A Survey of Basic Principle and Recent Development

Quantum algorithm puts serious threats to information security. Quantum cryptography offers new solutions to this problem. As an important branch of quantum cryptography, quantum secure direct communication (QSDC) transmits secret information directly through a quantum channel. QSDC has no key, no ciphertext, and eliminates the known security loopholes in traditional secure communication. QSDC has changed the structure of secure communication fundamentally. Here we give a survey of QSDC in terms of principle and recent developments.