The team of Professor Chen Xianfeng of Shanghai Jiaotong University and Professor Li Yuanhua of Shanghai University of Electric Power conducted further research based on the quantum direct communication theory of the team of Long Guilu, Vice President of the Beijing Institute of Quantum Information Science and Professor of Tsinghua University.
In the latest research, researchers innovatively used dual-pump optical parametric down-conversion technology to build a quantum entanglement distribution system with high anti-interference ability.
The experimental results show that the fidelity of the shared quantum state between nodes after communication remains above 85%, verifying the reliability of the scheme in long-distance communication.
After 300 kilometers of transmission, the number of photon pairs reaching the receiving node still reaches 300~400Hz (Hertz), which means that after encoding, the theoretical communication rate can reach several bits per second.
The breakthroughs of this research are mainly reflected in three aspects:
First, it breaks through the limitations of the traditional star network architecture and realizes the scalability of the fully connected network;
Second, by optimizing the entangled light source preparation technology, the transmission distance is increased to the order of 300 kilometers;
Third, an error correction mechanism based on quantum state reconstruction is established to ensure the stability of multi-node communication.
It is understood that the successful construction of this network system has laid an important foundation for the practical application of quantum communication networks.
In the future, related technologies can be applied to military command, government communications, financial transactions and other fields with extremely high requirements for information security.
The security of quantum communication is extremely high, mainly based on the principle of quantum non-cloning. Once the quantum state is measured, it will change, so any attempt to eavesdrop on quantum communication will be discovered.
For example, in quantum key distribution, the sender and the receiver transmit the key through the quantum state. If there is an eavesdropper, his measurement behavior will destroy the quantum state, and the receiver and the sender can detect it, so as to change the key and redistribute it, ensuring the security of information transmission.
Theoretically, as long as there are no loopholes in the protocol and implementation process of quantum communication, the key distribution during information transmission can be absolutely secure, which is difficult to achieve with traditional communication technology.