Introduction

As time goes on, unconditionally secure means of communication are more and more needed. As one of the key points of quantum informatics, quantum communication generally refers to those quantum technologies that transmit and transfer signals, information, or quantum states by moving quantum states, it has solved the problems of small information capacity and weak confidentiality, which cannot be broken through in classical communication, and has become a hot topic of research. Quantum communication is a new cryptographic communication technology that guarantees unconditional security in principle by quantum cryptography mechanisms that do not rely on computational complexity. It is the first practical quantum information technology that lays a theoretical foundation for building an “absolutely safe” communication system.