Science takes a step toward real-life lightsabers

A new state of matter makes the sci-fi sword seem possible. It could also give us computers nearly as fast as the speed of light.

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Eric Mack
2 min read

Not just a sci-fi sword?

20th Century Fox

Researchers from MIT and Harvard in 2013 managed to get photons, which are basically particles of light, to play nice with each other and create a new state of matter. Harnessing such a breakthrough could lead to actual quantum leaps in computing and perhaps even give us a real-world lightsaber

Now the same team has done it again. This time they observed not just photon pairs, but also groups of three photons interacting to make another completely new kind of photonic matter.

"What was interesting was that these triplets formed at all," explained MIT physics professor Vladan Vuletic in a news release.

The difference between normal light and what the researchers created is actually best illustrated by the example of a lightsaber like those in the Star Wars universe. Photons in those fictional lightsaber beams collide and crash into each other when they intersect, often with great consequences for the Empire or Jedi. But cross two beams of light from normal flashlights and the photons just pass right through each other like nothing. 

By passing a very weak laser beam through a dense cloud of ultracold rubidium atoms, the scientists managed to make photons interact and bind together in pairs and triplets -- kind of like an atom-size lightsaber.

Vuletic and Harvard professor Mikhail Lukin are lead authors of a paper explaining their findings published Thursday in the journal Science.

"What's neat about this is, when photons go through the medium, anything that happens in the medium, they 'remember' when they get out," co-author Sergio Cantu of MIT says. 

All this happens in a millionth of a second, but after it's over and the photons have traveled out of the cloud, they remain stuck together, which is a big deal because this interaction, or entanglement, could be used to advance quantum computing. 

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"Photons can travel very fast over long distances, and people have been using light to transmit information, such as in optical fibers," Vuletic says. "If photons can influence one another, then if you can entangle these photons, and we've done that, you can use them to distribute quantum information in an interesting and useful way."

The team plans to continue to investigate how photons can be made to interact with each other in controlled ways that could get us closer to speed-of-light computing and even more far-out concepts. 

Vuletic says sometimes it's hard to know what to expect from the finicky photons when they start to congregate.

"Can they be such that they form a regular pattern, like a crystal of light? Or will something else happen? It's very uncharted territory."  

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