Wits University achieved a breakthrough in a project to build Internet connectivity thousands or millions of times faster than fibre.
A world-first experiment conducted at the University of Witwatersrand has achieved a breakthrough in the project to use lasers to securely transmit data at extremely fast speeds.
In April, Prof. Andrew Forbes, head of the Structured Light Lab at the Wits School of Physics, described the “fastest Internet in the world.”
He described how patterns of light could be used to transmit data by acting as millions of individual channels of information packed into a tiny space, namely, one square millimetre of a laser beam.
Each one of these over a million patterns would function as a “tube” where light is independently modulated to communicate information, similar to how Wi-Fi or fibre Internet works today.
Fibre is already an established, commercialised communication system that works well today and delivers high Internet speeds by modulating a single light signal.
“But what if we could get more patterns to do the same thing and scoot them all into a small area of space?” Forbes asked earlier this year.
“We could, in the same fibre or the same free space link or the same Wi-Fi system, have thousands or millions of times the speed we have today.”
Using quantum lasers, this extremely fast Internet would also be highly encrypted, making it almost impossible to intercept. Examples of this process are already taking place today, Forbes said.
Earlier this year, an experiment conducted by one of his former students tested a light-based communication system via a satellite link between two countries separated by 13,000 km.
“Outside the lab in real-world environments, we have, at the quantum level, the equivalent of our present communication systems classically,” he said.
Photo of experiment conducted on the Wits West Campus roof, with an illustration of the laser beam. Credit: University of the Witwatersrand.
Forbes told MyBroadband that prior work on using patterns of light to significantly increase the bandwidth of communication systems faced a singular problem.
“The problem that has been holding the implementation back is that ‘patterns of light’ get distorted in real-world environments,” he said.
Forbes explained that one should imagine looking over a campfire at the scene behind it — there would be an apparent shimmer. This is the distortion caused by atmospheric turbulence.
In the latest experiment at Wits, researchers, including Forbes, have shown that there is a property of light that is immune to these distortions: the topology.
“The popular example of topology is the equivalence between donuts and coffee mugs. They look very different, but their topology is the same. They have the same number of holes (one),” he said.
“In usual communication, I send you donuts and coffee mugs as 0s and 1s, and this is my alphabet. But the distortion means that sometimes you cannot tell which is which.”
By using a topological alphabet, you can ignore what the object looks like and instead only count the number of “holes”. Researchers in South Africa have been able to do this with light.
“In our case, it is not the number of holes but rather a more abstract property that can take any value: 1,2,3… onwards. We don’t lose the size of the alphabet, but again form topological robustness,” he said.
“The result, which we demonstrated, is a large encoding alphabet that is robust to distortions. We did the tests over a 270m link from one building to another as proof of the idea.”
Researchers from Wits were joined by researchers from the University of Bordeaux in France on the quantum laser experiment, conducted on the roof of the Wits West Campus.
Forbes said that, with the experiment’s results and the topological alphabet in hand, the project to create the fastest Internet in the world as part of quantum research is one step closer.
“The only parts of the puzzle left before we can deploy the technology are to work out how to do fast encoding into topology,” said Forbes.
To do this, researchers will have to figure out how to make a topological detector. Forbes said that this effort was well on its way.
Using topology to remove the barrier of light distortion, researchers can now focus on finding ways to put information and data into the topology, and modulate it.
“We know how to do this with conventional patterns, so we hope we can convert that into topological encoding. Then we are ready to start the road from invention to product through innovation,” he said.
