Controlling Light with a Single Atom
Switches surround us as without them rooms would be dark and electronics could not be turned on. While this abundance makes them easy to forget, switches are very important tools that are needed in many situations. Researchers at the Vienna University of Technology have recently created a light switch consisting of a single atom, which could have potential with quantum communication.
Most people think of fiber optic cables as a means to carry optical signals over great distances, but with the proper modification, they can also be made into a bottle resonator. These resonators trap light by having it run in circles around its circumference, and getting the light in or out of the resonator is as easy as bringing it near a fiber optic cable. The process of the light jumping to the resonator is very sensitive, as the researchers discovered, as touching a single rubidium atom to the resonator prevents any light from entering it, or leaving it to enter another cable.
While this single-atom switch can definitely be used like a classical light switch, it can also be made into a quantum mechanical light switch. By putting the rubidium atom into a superposition so that it is both touching and not touching the resonator, the position of the light will also enter a superposition. This ability could thus be used for quantum information and communication purposes without relying on the rare machinery found only in laboratories.
Source: Vienna University of Technology