In a development that could make the advanced form of secure
communications known as quantum cryptography more practical, University of
Michigan researchers have demonstrated a simpler, more efficient single-photon
emitter that can be made using traditional semiconductor processing techniques.
Single-photon emitters release one particle of light, or
photon, at a time, as opposed to devices like lasers that release a stream of
them. Single-photon emitters are essential for quantum cryptography, which
keeps secrets safe by taking advantage of the so-called observer effect: The
very act of an eavesdropper listening in jumbles the message. This is because
in the quantum realm, observing a system always changes it.