Physicists Engineered a New Form of Light That Could Help With Quantum Computing

A team from MIT and other universities noticed that photons paired off and acted differently after being passed through a supercold cloud of atoms.
Shelby Rogers

Simple flashlights just inspired a team at MIT to create a unique (and potentially ground-breaking) addition to the study of quantum computing. When one shines two flashlights into a dark room to where beams cross, nothing in particular happens. However, the MIT team wanted to figure out a way to get these light beams to interact -- like a Star Wars lightsaber. 

One step closer to making lightsabers a reality

The latest research slightly "bent" traditional rules of physics to prove that photons in a light beam could interact. This new study puts the world one step closer to using photos in quantum computing (and yes, in making lightsabers a reality). 

For Professor Vladan Vuletic, who led the researchers, harnessing photons this way was certainly not easy. 

"The interaction of individual photons has been a very long dream for decades," Vuletic said in a statement. Vuletic also worked with Professor Mikhail Lukin from Harvard University, and the two have been working on the project for years until they finally had a breakthrough in 2013. The most recent research emphasized the potential power of photons. 


The team shone very weak laser beams through a dense cloud of ultracold rubidium atoms. Instead of exiting the cloud as single, randomly space photos, the team noticed that the photons paired off into groups of two or three. Thus, the researchers researched further into a possible interaction between the photons. 

Ultimately, Vuletic and the team concluded that photons can attract or entangle each other. Knowing that photons interact in these ways, the team now wonders if they can be harnessed for complex, light-based, fast needs like quantum computing. 

"So it was an open question: Can you add more photons to a molecule to make bigger and bigger things?" Vuletic said. 

Aditya Venkatramani of Harvard also served as part of the team. The researchers not only tracked the number and rate of photons traveling through the cooled rubidium atom cloud, they also took note of what phase the photons traveled in before and after they passed through the cloud.

"The phase tells you how strongly they're interacting, and the larger the phase, the stronger they are bound together," Venkatramani said.

The team also noted that three-photon groups exited the cloud at the same time with a different phase compared to what it was pre-interaction. 

"This means these photons are not just each of them independently interacting, but they're all together interacting strongly," Venkatramani continued.

"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."

Vuletic and the team anticipate this discovery being harnessed for a number of different applications. 

"Photons can travel very fast over long distances, and people have been using light to transmit information, such as in optical fibers," Vuletic said. "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."

However, the researchers openly admitted that their discoveries are far from over and they certainly want to do more digging into the movements and activities of photons in different circumstances.

"It's completely novel in the sense that we don't even know sometimes qualitatively what to expect," Vuletic says. "With repulsion of photons, 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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