In times of geopolitical uncertainty, growing cyber threats and the rapid emergence of quantum computers, secure communication is becoming one of the key issues of the present. The systems on which state administration, the financial sector and critical infrastructure rely are increasingly vulnerable. This challenge is the inspiration for new research by scientists from the Department of Optics, Faculty of Science, Palacký University in Olomouc (UPOL), who, in collaboration with the Technical University of Denmark (DTU), have proposed a new approach to quantum key distribution (QKD).
The QKD mechanism uses the principles of quantum physics to securely share encryption keys using quantum states of light. Any eavesdropping attempt in such a system will be reflected and can be detected. However, existing QKD systems operate mainly point-to-point: one sender, one receiver, one connection. This is proving to be a major limitation in today’s dense and dynamic communication networks. The team from Olomouc and DTU therefore came up with a “one-to-many” solution. The proposed protocol allows quantum encryption keys to be distributed simultaneously and independently to multiple users from a central source. This concept is part of a broader architecture called continuous-variable quantum passive optical network (CV-QPON).
The security of the technology is not based on complex assumptions about the behavior of other users, but on physically measurable quantities, in particular the amplitude of the received optical signal. Users can set the level of trust and security of their keys according to the specific situation. “It is a conscious compromise,” says Vladyslav Usenko from the Department of Optics, who leads the Quantum Communication Theory Team. “We prioritize simplicity, speed, and information transfer capacity, which are key for real networks.”
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