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Computing With Light

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D:        Y’know Yaël, it doesn’t make sense to use electronics for computers.  Computers would be much faster, smaller, and consume less energy if they used light signals instead of electrical signals.

Y:        That’s why many scientists are racing to figure out how to make computers that use light, Don. But, there are some hard problems to solve. For one thing, researchers need something to replace the transistors that perform computations in electronic computers.

D:        What sorts of things have they tried?

Y:        Let’s take one example. In 2019 a team of Canadian researchers published evidence that a type of polymer could perform mathematical operations for a light-based computer.  A polymer is a substance consisting of large molecules made out of chains of repeating subunits. They shined patterns of light into the top and sides of a glass case containing the polymer. The pattern of dark and bright light bands corresponded to ones and zeros of the binary arithmetic that computers use.

D:        So, how does the polymer compute?

Y:        Just as a transistor responds to the electric currents it receives, the polymer responds chemically to the light it receives, forming different patterns of filaments in response to different combinations of light patterns. These chemical changes in the polymer perform the computation. Another beam of light detects the filament patterns, which correspond to the results of the computation.  The researchers have so far performed additions and subtractions this way, and plan to extend the technique to other computational operations soon.

D:        It seems to me that discovering new ways to compute could make powerful neural network computers common, and lead to new breakthroughs in artificial intelligence.
Photo of computer servers.

Computers would be much faster, smaller, and consume less energy if they used light signals instead of electrical signals. (Wikimedia Commons)

For various reasons, it doesn't really make sense to use electronics for computers. Computers would be much faster, smaller, and consume less energy if they used light signals instead of electrical signals.

That's why many scientists are racing to figure out how to make computers that use light. There are still some hard problems to solve, though.

For one thing, researchers need something to replace the transistors that perform computations in electronic computers.

In 2019, a team of Canadian researchers published evidence that a type of polymer could perform mathematical operations for a light-based computer. A polymer is a substance consisting of large molecules made out of chains of repeating subunits.

They shined patterns of light into the top and sides of a glass case containing the polymer. The pattern of dark and bright light bands corresponded to ones and zeros of the binary arithmetic that computers use.

Just as a transistor responds to the electric currents it receives, the polymer responds chemically to the light it recieves, forming different patterns of filaments in response to different combinations of light patterns, which correspond to the results of the computation.

The researchers have so far performed additions and subtractions this way, and plan to extend the technique to other computational operations soon. Discovering new ways to compute could make powerful neural network computers common, and lead to new breakthroughs in artificial intelligence.

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