Designing the Traffic Signals of the Quantum Internet

The quantum internet is great: totally beyond-encrypted information traveling around present-day fiber-optic cables not just between bogglingly fast quantum computers, but actually forming massive and even more bogglingly fast distributed quantum computers. Total security and computing/network speeds to put anything operational in the year 2011 to absolute shame.

As tech goes, quantum computing and the quantum internet are still fairly theoretical: a great idea with tons of research and resources behind it. But still a question mark as far as becoming reality. On the networking side of things, one of the biggest challenges is coming up with hardware that can transmit quantum information intact. A big problem is that quantum systems are wicked fragile. That is, if you disturb the system, it collapses and is unusable as information.

When we're talking about quantum networking in practical terms, the situation gets worse because we need to be able to use fiber-optic tech already in place. Which is reasonable: quantum information is transmitted via photons, which are "just" units of light.

A problem arises at switching points, where it's necessary to tell the quantum information to go one way or another. And, of course, to have any sort of real network, you need switching points, right?. So how do you interfere with the information in a way that doesn't disturb it? Researchers at Northwestern University think they've met this goal with a new all-optical switching mechanism that allows information to travel through it unaffected, or at least unaffected within a small margin. The new research is detailed in the Physical Review Letters journal.

So, this is a pretty solid "eureka" for the quantum internet. The Northwestern team was able to take two entangled photons (which are "linked" via no medium and communicate instantaneously over an infinite distance), and fire them through a standard telecom-grade fiber-optic channel and through this new switch. The information was able to make it through intact—in sciencespeak, “a controlled-bit-flip on a two-qubit subspace of a five-qubit, two-photon state” went down. And, thus, the quantum internet creeps closer.

A quick refresher on quantum computing, by the by. How normal computing works is that either a "1" or a "0" passes through a switch, one at a time. Each one of those that pass through is known as a "bit" of information. Quantum computing takes advantage of a property known as superposition. Simply: instead of either/or, a unit of information can be both a 1 and a 0 simultaneously. This is called a qubit and might just be the future of information (and maybe our understanding of reality, man).

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Reach this writer at michaelb@motherboard.tv.