4D Quantum Encryption Packs Messages Onto Photons

In an age of large scale hacks, security experts think that 4D quantum encryption may be the best way to keep communications safe from prying eyes — by literally beaming it through the air as a stream of photons. To make this even more secure, they’ve devised something called 4D or “high-dimensional” quantum encryption, in which twice the data of “regular” 2D quantum encryption can be squeezed onto each photon. Rather than each photon just representing a 1 or 0, as is the case with 2D quantum encryption, in 4D encryption each photon encodes two bits of information, which provides the four possibilities of 01, 10, 00, or 11.

So far, so good, right? The problem is that — until now — this technique hadn’t been demonstrated in the real world. As neat a solution as it is in the lab, the problem in applying it to the real world is air turbulence, which can distort the optical signal. That may not be the case any more, however, because an international team of researchers has demonstrated for the first time that it is possible to use this form of communication in even the crowded noisy environment of a modern city.

For their test, the researchers transported their laboratory optical kit to two different rooftops at the University of Ottawa, covered in wooden boxes to help protect them. They then demonstrated the efficacy of their 4D quantum encryption across two buildings 0.3 kilometers apart. The transmissions carried an error rate of 11 percent, which is below the level required to maintain a secure connection. Compared to 2D encryption, they were able to transmit 1.6 times more information per photon — making it both more secure and more efficient.

Next up, the researchers want to implement their approach on a three link network, with each link being 5.6 kilometers apart, using more than four dimensions. They will also continue to develop their special optics technology that is able to smartly compensate for any turbulence. Eventually, the goal is connect the network to an existing network in Ottawa.

Right now, the research is still at proof of concept stage, but it’s definitely exciting if you’ve got any kind of interest whatsoever in keeping your communication secure.

A paper describing the work was recently published in the journal Optics.

Security experts demonstrate 4D quantum encryption in action

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