Developed at the Joint Quantum Institute, it consists of a nanosize sandwich of arsenic and indium. It is so tiny that it can emit only discrete wavelengths, as if it were an atom. It was placed inside a photonic crystal that had been bored with several tiny holes, enabling light to pass only through the crystal, for a narrow range of wavelengths.  When light traveled through the waveguide adjacent to the resonant cavity, some amount of light entered into the cavity and reacted with the quantum dot. This interaction can modify the waveguide’s transmission properties. To create a switching action, 140 photons are required in the waveguide. In the JQI experiment, however, only six photons are required to throw the switch.

For more information, visit: www.jqi.umd.edu