Quantum communication is the central part of quantum information technology. It has the advantages of absolute secrecy, large communication capacity, fast transmission speed, and so on. It can complete the particular tasks that classical communication can not achieve. Quantum communication can use the private key system, which can not be deciphered to realize the real sense of secure communication, so quantum communication has become the forefront of science and technology in the world. Quantum communication uses the quantum state as an information element to realize the effective transmission of information. It is another revolution in the history of communication after telephone and optical communication.
The main components of quantum communication：
Quantum secret key distribution：
Quantum secret key distribution is not used to transmit confidential content. Still, it is to establish and communicate cipher book, that is, to assign the private key to both sides of personal communication, commonly known as quantum cryptography communication.
In 1984, Bennett of the United States and brassart of Canada proposed the BB84 protocol, which uses quantum bits as information carriers to encode quantum states by using polarization characteristics of light to realize the generation and safe distribution of secret keys. In 1992, Bennett proposed a B92 protocol based on two nonorthogonal quantum states with simple flow and half efficiency. Both of these schemes are based on one or more sets of orthogonal and nonorthogonal single quantum states. Finally, in 1991, Ekert of the UK proposed E91 based on the two-particle maximum entanglement state, namely the EPR pair.
In 1998, another six-state quantum communication scheme was proposed for polarization selection on three conjugated bases composed of four polarization states and left and proper rotation in the BB84 protocol. BB84 protocol has been proved to be a safe critical distribution method, which has not been broken by anyone so far. The principle of quantum uncertainty and quantum non-cloning ensure its absolute security. Therefore, the EPR protocol has essential theoretical value. It connects the entangled quantum state with secure quantum communication and opens up a new way for secure quantum communication.
quantum teleportation：
The theory of quantum teleportation proposed by Bennett and other scientists in six countries in 1993 is a pure quantum transmission mode that uses the channel of two-particle maximum entangled state to transmit unknown quantum state, and the success rate of teleportation will reach 100% [2].
In 199, a. Zeilinger group of Austria completed the first experimental verification of the principle of quantum teleportation in the laboratory. In many films, such a plot often appears: a mysterious figure suddenly disappears in one place suddenly seems in place. However, because quantum teleportation violates the principle of quantum non-cloning and Heisenberg uncertainty in quantum mechanics, it is just a kind of science fiction in classical communication.
However, the exceptional concept of quantum entanglement is introduced into quantum communication, which divides the unknown quantum state information of the original into two parts: quantum information and classical information, which makes this incredible miracle happen. Quantum information is the information not extracted in the measurement process, and classical information is the original measurement.
Progress in quantum communication：
Since 1994, quantum communication has gradually entered the experimental stage and striding forward to the practical goal, which has excellent development value and economic benefits. In 1997, pan Jianwei, a young Chinese scientist, and bow meister, a Dutch scientist, experimented and realized the remote transmission of unknown quantum states.
In April 2004, Sorensen et al. Realized 1.45km data transmission between banks for the first time by using quantum entanglement distribution, marking the quantum communication from laboratory to application stage. At present, quantum communication technology has attracted significant attention from governments, industry, and academia. Some famous international companies are also actively developing the commercialization of quantum information, such as British telephone and Telegraph Company, bell, IBM, at & T laboratories in the United States, Toshiba company in Japan, Siemens company in Germany, etc. Furthermore, in 2008, the European Union’s “global secure communication network development project based on quantum cryptography” set up a 7-node secure communication Demonstration and verification network.
In 2010, Time magazine of the United States reported the success of China’s 16 km quantum teleportation experiment in the column of “explosive news” with the title of “leap of China’s Quantum Science,” indicating that China can establish a quantum communication network between the ground and the satellite [3]. In 2010, the national intelligence and Communication Research Institute of Japan and Mitsubishi Electric and NEC, ID quantified of Switzerland, Toshiba Europe Limited, and all Vienna of Austria established the six nodes metropolitan quantum communication network “Tokyo QKD network” in Tokyo. The network focuses on the latest research results of research institutions and companies with the highest level of development in quantum communication technology in Japan and Europe.
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Post time: May-05-2023