(Xinhua): A group of Chinese scientists has successfully created a workable system that turns quantum direct communication from a theoretical idea to a useful application, and they have put out a novel theory on one-way quantum direct communication. Their research was just released in Science Advances.

Experts from Tsinghua University, North China University of Technology, and the Beijing Academy of Quantum Information Sciences made up the study team, which in an optical fiber communication test set a new record for a transmission distance of 104.8 kilometers. They were successful in keeping the transmission steady for 168 hours at a rate of 2.38 kilobits per second.

The aim of quantum direct communication, proposed by a group from Tsinghua University and directed by Long Guilu, will be used to permit quantum states to function as carriers for secure communication. Relevant features of this technique include eavesdropping detection and prevention, compatibility with existing infrastructure, and easy management procedures. Transfer of information in such an accomplished way gives an extreme class of security to this communication technique.

Communications in quantum communication systems have been confronted with the fundamental issue of providing safe and reliable communication utilizing quantum states of very low energy. Quantum states are vulnerable to perturbation, especially in quantum channels that are extremely noisy, have high losses, and are possibly under a serious threat of eavesdropping. Hence, the design and implementation of reliable quantum communication systems become quite tough.

Previously, bidirectional protocols were employed where both sides of the quantum communication system would exchange quantum states. The potential to enhance communication performance was severely constrained by the significant system loss caused by this approach.  In 2022, Long and his group achieved a world record for 100-kilometer quantum direct communication, although the speed was only 0.5 bits per second, meaning that just a few letters could be sent.

Long considered this accomplishment, and although it was a very remarkable milestone, one could not hide the fact that the extremely poor transmission rate was an obvious disadvantage. He might have stated that one way of it corresponding to half distance in quantum state transmission was a great improvement in loss as well. 

However, the progress is usually from one issue to the other; in this case, optimization of the channel mechanism has been the focus of these scientists. With other important technologies, high noise-high-loss channel coding algorithms were invented. Now it would be possible to bring forward a theoretical proposition for such kind of one-way quantum direct communication and also overcome all other technical barriers, which previously reduced the progress of this field.

These developments have resulted in a new communication system with a notable improvement in performance.  With a communication rate 4,760 times higher than the 2022 system, the newly developed system shows a notable improvement in the capabilities of quantum direct communication systems.  This notable increase in transmission speed shows how successfully the team overcame previous obstacles.

According to Long, this result suggests that quantum direct communication systems could soon be applied in fields requiring the highest degree of information security.  These systems are perfect for sectors like banking and government operations that handle particularly sensitive data because of their robust security features and ability to prevent unauthorized access or modification.

There are two main types of quantum secure communication systems.  One is quantum key distribution, which uses quantum states to create encryption keys and sends encrypted data across traditional communication channels.  This method's high transmission rate makes it suitable for applications requiring fast data transfer.

The second type is quantum direct communication, which transmits information directly using quantum states.  This method has the advantage of intrinsic security since any attempt to listen in will cause the quantum states to destroy themselves, safeguarding the data's privacy.  Rather than relying solely on external encryption methods, this system uses the fundamental properties of quantum mechanics to maintain information security.

This development of one-way quantum direct communication will drastically affect future secure communication systems. With a considerable reduction in energy losses and enhanced transmission efficiencies, the new system lays the groundwork for a range of high-security applications in quantum communication technologies, making them more dependable and scalable.

As quantum direct communication continues to develop, the actual implementation of these technologies will be closely observed. Experts project that with further development, these systems will have the power to transform secure communications and provide a level of security that cannot be attained by conventional encryption methods today. The successful construction of this one-way quantum communication system is an important step in that direction, giving a glimpse of the secure information exchange of the future.