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Researchers at the Technical University of Denmark (DTU) have successfully demonstrated quantum encryption over 62 miles (100 km).
The approach used by the team is called Continuous Variable Quantum Key Distribution (CV QKD), and their recent feat is a record for encryption achieved using this approach, which works well with existing internet infrastructure.
In quantum computing, technology companies are rushing to build the future of computing that will allow them to carry out complex calculations in record-breaking times.
However, this computing prowess could also be deployed to crack the existing encryption systems, leaving data privacy in the open and systems prone to surveillance.
While such a world is still far away, cyber security researchers are busy working on newer forms of encryption that even the most advanced quantum computers will find tough to crack. The possible solution to quantum computing’s problems will come from the quantum realm.
What is Quantum Key Distribution?
When data is sent from one user to another, it is encrypted using a secure key available only to the sender and the recipient. The encryption is compromised if a third party gains access to this key. Therefore, researchers are keen to ensure that the key exchange remains secure.
In Quantum Key Distribution (QKD), cryptographic keys are exchanged using light from photons. Researchers have used photons’ unique quantum mechanical properties to create unique keys. Since photons are in a quantum state, any attempt to observe them changes their state, making it impossible to read them without disturbing them.
“It is impossible to make a copy of a quantum state, as when making a copy of an A4 sheet – if you try, it will be an inferior copy,” explains Tobias Gehring, an associate professor in the Department of Physics at DTU. “That’s what ensures that copying the key is impossible. This can protect critical infrastructure such as health records and the financial sector from being hacked.”
However, using a feature from the quantum realm also brings limitations, such as the inability to be consistent over long distances. This is what the DTU researchers addressed in their work.
Exchanging encryption over long distances
The DTU researchers used machine learning to improve three factors that limited the exchange of quantum keys. The researchers learned that noise disturbances arising from electromagnetic radiation could distort or even destroy the keys. By detecting noise early on in the system, the researchers were able to reduce the impact much more effectively, a press release said.
Additionally, the research team was also able to correct errors in the transmission of the keys caused by interference or imperfections in the hardware.
Interestingly, the CV QKD technology can be rolled out without a new technological platform. Instead, it works with the existing internet infrastructure of fiber optic cables. The fiber optic network is the backbone of digital communication, which has been used for a long time and can also be used to distribute quantum keys in the quantum age.
CV QKD has been demonstrated over short distances, so the 62-mile key distribution is a landmark achievement.
The researchers plan to set up a secure communication network for different Danish ministries to demonstrate that the technology can be used in real-life scenarios. “We will also attempt to generate secret keys between, for example, Copenhagen and Odense to enable companies with branches in both cities to establish quantum-safe communication,” Gehring added in the press release.
The research findings were published in the journal Science Advances.
