The Electronics and Telecommunications Research Institute (ETRI) announced on the 30th that it has developed a new technology that enables stable quantum communication even in moving environments such as satellites, ships, and drones through joint research with the Korea Advanced Institute of Science and Technology (KAIST).
Quantum communication is a high-precision technology for transmitting information in the quantum state of light, but it has struggled with stability in wireless moving environments due to significant impacts from weather and surrounding environmental changes. In particular, delivering stable quantum states in real-time changing environments such as sky, sea, and air has been extremely difficult.
In response, the research team established for the first time in the world the theory of 'Measurement Protection (MP)', which allows stable Quantum Key Distribution (QKD) without measurement corrections, and succeeded in experimentally verifying it. Quantum key distribution technology refers to a technology that distributes encryption keys, which are fundamentally impossible to eavesdrop on, using the principles of quantum mechanics.
Existing quantum key distribution protocols required repeated calibration of the receiving-side measurement device whenever the channel state changed. However, this study demonstrated that stable key distribution is possible regardless of the channel state with only simple local operations.
The research team implemented a long-distance transmission environment with a maximum loss of 30dB over a 10m free space interval, confirming that quantum transmission and measurement proceeded smoothly even under adverse conditions. As a result, the newly developed system improved the maximum allowable system limit of the Quantum Bit Error Rate (QBER), which refers to the proportion of errors among transmitted quantum bits, by 20.7% compared to the existing standard. This means that stable quantum key distribution is possible without additional measurement corrections if the error rate of received quantum bits is below 20.7%.
The research team noted that this holds significant meaning as it opens up the technical possibility of stably exchanging quantum information even while in motion and expressed hope that quantum technology could be applied in various fields such as secure communication between satellites and ground stations and drone and maritime communication.
Meanwhile, ETRI also proposed an experimental correction method for the crucial issue of 'polarization-dependent loss' in the practical application of quantum key distribution. Polarization-dependent loss refers to signal loss occurring as the polarization state of light changes. The research team experimentally demonstrated that the developed method could achieve stable key distribution without performance degradation when applied to polarization-based quantum key distribution systems. It is expected to contribute to the commercialization of small and lightweight quantum key distribution equipment in the future.
The relevant research results were published as cover papers in the international journals 'Journal on Selected Areas in Communications' in May and 'Advanced Quantum Technologies' in March.
References
Journal on Selected Areas in Communications(2025), DOI: https://doi.org/10.1109/JSAC.2025.3568037
Advanced Quantum Technologies(2025), DOI: https://doi.org/10.1002/qute.202570006