Two stopped light pulses interact with each other

For the first time, physicists have experimentally demonstrated the interaction of two motionless light pulses. Because the stopped light pulses have a long interaction time, it increases the efficiency with which one photon can switch the path of a second photon. This ability, called photon switching, could have applications in quantum information technologies and photonic circuits, which use light rather than electric currents to manipulate information. Here, the scientists demonstrated an optical switching efficiency that is even higher than the expected limit, and they predict the efficiency can be increased further.