Scientists coax photons to bind into molecules for first time

Peter Reuell in the Harvard Gazette:

Scientists from Harvard University and the Massachusetts Institute of Technology (MIT) are challenging the conventional wisdom about light, and they didn’t need to go to a galaxy far, far away to do it.

Working with colleagues at the Harvard-MIT Center for Ultracold Atoms, a group led by Harvard Professor of Physics Mikhail Lukin and MIT Professor of Physics Vladan Vuletic managed to coax photons into binding together to form molecules — a state of matter that until recently had been purely theoretical. The work is described in a Sept. 25 paper in Nature.

The discovery, Lukin said, runs contrary to decades of accepted wisdom about the nature of light. Photons have long been described as massless particles that don’t interact with each other. Shine two laser beams at each other, he said, and they simply pass through one another.

Photonic molecules, however, behave less like traditional lasers and more like something you might find in science fiction: the light saber.

More here.