Scientists from Harvard and MIT joined together to create a state of matter that looks like it belongs in a galaxy, far, far away rather than in Massachusetts. A group led by Harvard Professor of Physics Mikhail Lukin and MIT Professor of Physics Vladan Vuletic managed to create molecules formed from photons bound together, a union that produces a result that resembles a light saber.
"Most of the properties of light we know about originate from the fact that photons are massless, and that they do not interact with each other," Lukin said. "What we have done is create a special type of medium in which photons interact with each other so strongly that they begin to act as though they have mass, and they bind together to form molecules. This type of photonic bound state has been discussed theoretically for quite a while, but until now it hadn't been observed.”
"It's not an in-apt analogy to compare this to light sabers," Lukin added. "When these photons interact with each other, they're pushing against and deflect each other. The physics of what's happening in these molecules is similar to what we see in the movies."
To get the photons to interact with one another, the team cooled rubidium atoms in a vacuum chamber to just a few degrees above absolute zero, The Independent reported. They then fired photons into the cloud of atoms and were surprised to see them emerge on the other side as a single molecule.
"It's a photonic interaction that's mediated by the atomic interaction," Lukin said. "That makes these two photons behave like a molecule, and when they exit the medium they're much more likely to do so together than as single photons."
"We do this for fun, and because we're pushing the frontiers of science. But it feeds into the bigger picture of what we're doing because photons remain the best possible means to carry quantum information. The handicap, though, has been that photons don't interact with each other."