Emitter Generates Identical Single Photons on Demand

Researchers at Lawrence Berkeley National Laboratory have developed a method of generating single identical photons on demand, a crucial step in realizing quantum communication. The photon emitter is based on a common 2D semiconductor material (tungsten disulfide, WS2), which the researchers grew on a graphene sheet. To facilitate photon emission, the material has a sulfur atom removed from its crystal structure. That imperfection serves as a point where the application of an electric current can generate the photon. Through simulations and experimentation, the team determined exactly where to introduce an imperfection to the structure. Then, using the gold-coated tip of a scanning tunneling microscope, an electron is injected...