Secure quantum communication in a nuclear reactor launched in the US — how it works

American researchers from the University of Purdue and Oak Ridge National Laboratory have demonstrated for the first time in the world the ability to secure quantum communication in an operating nuclear reactor. 

It is noted, that scientists have quantized the keys to the Toshiba at Purdue’s PUR-1 reactor to launch world’s first quantum encryption systems at a nuclear facility. The world is currently searching for efficient and environmentally friendly energy sources. Small modular reactors and microreactors are an alternative to large nuclear power plants.

Although such reactors produce significantly less nuclear waste than traditional nuclear power plants, they face the same security issues and remain vulnerable to cyberattacks. Current methods encryption are quite powerful today, but further development of quantum technologies can quickly turn these methods into obsolete ones. 

While other countries have switched to digital reactor control systems, PUR-1 is still the only fully digital nuclear reactor in the United States, using screens, keyboards, and Ethernet cables instead of knobs and analog systems to control operations. The control and instrumentation system is fully digital. American researchers team up with Japanese company Toshiba to test the QKD secure quantum communication system at the reactor. 

System QKD uses quantum mechanics and measurements of a quantum mechanical system to disturb quantum states. This allows you to easily find out if someone has tried to break into the system and what part of the information may have been lost. 

The efficiency of the system was tested by connecting two nodes directly to the reactor. They exchanged secure quantum keys over a single-mode fiber optic cable. To simulate the deployment scenarios, the researchers introduced delay lines and attenuatorsa special passive device that reduces the voltage, current, or power of electrical or electromagnetic oscillations to introduce distance and interference between nodes, and further tested their performance. 

The test results showed that the system stably generated keys at 320 Kbps and operated with a 3.8% quantum-bit error rate over a distance of 54 km. When limited to 68 basic signals, the researchers added that encryption with a one-time cipher worked over a distance of 135 km.

The system delay during encryption and decryption was less than half a second At the same time, researchers have found ways to buffer backup keys in case of connection failure.

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