Light, as we know it, is actually made up of a bunch of smaller particles. These particles are called photons; they have no mass and they do not interact with each other. They simply pass by each other, even when you place them in each other’s paths.
A new experiment from a team of scientists out of Massachusetts Institute of Technology and Harvard University, however, has demonstrated how photons could bind together in pair or even trios. This is the first time we have ever known of photons interacting with each other. This new interaction between photons is known as attraction, fittingly, but more importantly, looks to somehow result in photons acquiring mass in the process. And this is important because this newly-acquired mass actually added some heft to the photons—albeit, a very light weight—to the point that it sowed them down from their typical speeds of 300,000 km per second by nearly 100,000 times.
Harvard physicist Mikhail Lukin explains, “What we have done is create a special type of medium in which photons interact with each other so strongly thaty they begin to act as though they have mass, and they bind together to form molecules.”
Lead study author Vladan Vuletic, of MIT, notes, “Photons can travel very fast over long distances, and people have been using light to transmit information, such as in optical fibers. 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.”
He adds, “The interaction of individual photons has been a very long dream for decades.”
The researchers explain the physics behind the photon interactions in this hypothesis: “As a single photon moves through the cloud of rubidium atoms, it briefly lands on a nearby atom before skipping to another atom, like a bee flitting between flowers, until it reaches the other end. If another photon is simultaneously traveling through the cloud, it can also spend some time on a rubidium atom, forming a polariton — a hybrid that is part photon, part atom. ..The researchers found that this same phenomenon can occur with three photons, forming an even stronger bond than the interactions between two photons.”
Most importantly, the researchers hope expect that this discovery could lay the groundwork for photons to replace electrons in technology which can entangle, encode, and deliver information at extremely high speeds.