Quantum Cryptography Enables Untappable Communication

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Quantum Cryptography Enables Untappable Communication

Viennese quantum cryptography researchers from the Austrian Academy of Sciences have in collaboration with the AIT, achieved for the first time a quantum-physically encrypted network between four active participants. This scientific breakthrough has been honored with a cover story in the journal “Nature”. In a quantum physics experiment, researchers at the Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, in Vienna worked together with the Austrian Institute of Technology (AIT) to connect four participants within a quantum network, such that each of them could exchange encrypted messages with any other participant. This represents a milestone on the way to a quantum encrypted Internet.

The quantum Internet of the future should enable completely tap-proof communication between users worldwide. Instead of strong light signals used in classical communication technology, individual light particles (photons) are used to generate a cryptographic key. With this, data can then be encrypted and sent using classical techniques. If the recipient has the same key, they can decipher the data. The security of this process is based on a law of quantum mechanics: it is impossible to copy the state of a single light particle error-free. And if somebody tries, it generates errors in the transmission and blows their cover. By contrast, in a conventional network, messages can be copied indefinitely without leaving a trace.

How to use quantum cryptography in networks is known in principle, explains Rupert Ursin, quantum physicist and group leader at the Austrian Academy of Sciences.

However, so far, this has only been experimentally implemented with great restrictions,

continues the co-author of the study now published in “Nature”. In most cases, previous quantum networks were only able to connect two active participants with guaranteed security. By contrast, highly complex and error-prone hardware setups were required to connect several participants, ultimately allowing only limited communication links.

Author: Tim Cole
Image Credit: Nature

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