Sticky Light: Physicists discover new Photon Interactions

Light is made of little particles called photons that usually don’t interact. Imagine how strange it would be if the light from your window ricocheted off the light from computer screen! Our brains couldn’t make sense of these images and we’d be stuck in a blurry—albeit bright—world.

Professors Vladan Vuletic and Mikhail Lukin, at MIT have made this mindbender a reality. By shining a weak laser (only a few photons at a time) through a dense cloud of ultracold rubidium atoms, researchers have observed a three-photon bound state. Instead of not interacting like normal light, suddenly photons want to cling together strongly. The researchers posit that the photons are jumping from atom to atom. If neighboring atoms that ‘caught’ photons interact, their photons can get twisted up in the interaction and stick together.

While photons are massless, this new state has a mass slightly smaller than the electron, and travel much more slowly. These groups were able to produce photon pairs in 2013, but the recent, more complicated photon-state is a signal that there might be even more complicated interactions to detect.

This discovery itself is exciting, but it is even more intriguing to consider the implications on quantum computing. These three-photon states can transmit a lot of information if entangled, and light can travel far through optical fibers. Scientists hope to build larger, more complicated structures. This achievement and future innovations might lead to extremely efficient algorithms and computing.

Managing Correspondant: Cari Cesarotti