Light Sabers - a new form of matter!

Harvard and MIT scientists have successfully manipulated photons to act like molecules. Normally, light waves do not react with each other. An example from the article: if you shine two lasers at one another, the photons just pass through each other. By reacting with other photons, the photons are acting like molecules and elements that have mass and are able to react with one another. Does this defy physics as we know it? Not necessarily. According to an effect called the Rydberg blockade, when an atom is excited, nearby atoms cannot be excited to the same degree. In practice, the effect means that as two photons enter the atomic cloud, the first excites an atom, but must move forward before the second photon can excite nearby atoms. As the photons that were fired into the cloud used in the experiment exit the cloud, the photons left bound together act like a molecule would. 

Normally mass-less particles reacting with one another? Big whoop, right? Well, photons remain the best possibility of advancing technology related to carrying quantum information. The MIT and Harvard scientists admit that the handicap is that photons don't react with each other. If the binding of photons could be manufactured stably, then the field of quantum information logic could be pushed to new frontiers (and perhaps light sabers and ray guns would finally be real!) and who knows what else...

 Stock image of light sabers used in association with the article.

Journal Reference:

1. Ofer Firstenberg, Thibault Peyronel, Qi-Yu Liang, Alexey V. Gorshkov, Mikhail D. Lukin, Vladan Vuletić. Attractive photons in a quantum nonlinear medium. Nature, 2013; DOI: 10.1038/nature12512