light stored as sound

For the first time ever, researchers have stored light-based data as sound waves on a computer chip – something the scientists compare to capturing lightning as thunder.

While that may sound somewhat unusual, this conversion is significant if we ever wish to shift from our present, inefficient electronic computer systems, to light-based computers that transfer information at the speed of light.

Light-based or photonic computer systems have the potential to run at least 25 times faster than your computer, not to point out the fact that they won’t produce any heat or suck up power like existing units. This is because they, in concept, would process information in the form of photons instead of electrons.

We say in concept, because, in spite of firms such as Intel and IBM pursuing light-based computing, the transition is easier mentioned than done.

Coding data into photons is straightforward enough – we already do this when we send data using optical fibre. But discovering a way for a pc chip to be able to retrieve and process data saved in photons is hard for the one thing that makes light so interesting: it is too damn fast for current microchips to read.

This is why light-based data that flies across internet cables is currently converted into slow electrons. But a better alternative could be to decelerate the light and turn it into sound.

And that is precisely what researchers from the University of Sydney in Australia have now accomplished.

“The data in our chip in acoustic form travels at speed 5 orders of magnitude slower than in the optical domain,” said research supervisor Birgit Stiller.

“It is like the difference between thunder and lightning.”

This implies that computer systems will have the benefits of data delivered via light – high speeds, no heat caused by way of electronic resistance, and zero interference from electromagnetic radiation – but would also be able to slow information down enough in order that computers chips may do something useful with it.

“For [light-based computers] to become a commercial reality, photonic data on the chip must be slowed down so that they can be processed, stored, routed,  and accessed,” said one of the researchers, Moritz Merklein.

“This is the most important step ahead in the field of optical data processing as this idea fulfils all requirements for present and future generation optical communication systems,” added Benjamin Eggleton.

The team did this by developing a memory system that accurately transfers between light and sound waves on a photonic microchip – the type of chip that will be used in light-based computers.

You can see how it operates in the video below:

Initially, photonic info enters the chip as a pulse of light (yellow), where it connects with a ‘write’ pulse (blue), producing a sound wave that saves the data.

Another pulse of light called the ‘read’ pulse (blue), then accesses this acoustic data and transfers as light once again (yellow).

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While unobstructed light will go through the chip in 2 to 3 nanoseconds, once kept as an acoustic wave, information can stay on the chip for up to 10 nanoseconds, long enough for it to be recovered and processed.

The fact that the team were able to transform the light into acoustic waves not just slowed it down, however likewise made information retrieval more accurate.

And, unlike previous efforts, the system worked throughout a broad bandwidth.

“Building an acoustic buffer inside a chip enhances our ability to manage details by many orders of magnitude,” stated Merklein.

Stiller added “Our system is not limited to a narrow bandwidth. So unlike previous systems, this allows us to keep and obtain details at numerous wavelengths at the same time, greatly increasing the performance of the device.”

The research has been published in Nature Communications.


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