LONDON More secure optical networks are a step closer following a breakthrough involving quantum devices that was reported Thursday (Jan. 12) by Toshiba Research Europe Ltd. (TRRL) and scientists from the University of Cambridge.
The group reported in this week’s Nature on development of a quantum device that produces entangled photons made from pairs of photons whose fundamental properties are inextricably linked.
As well as making optical links safe from hacking, the researchers said the advance could play an important role in manufacturing semiconductors, building scalable quantum computers and achieving more sensitive medical diagnostics.
Unlike normal light, in which the photons are distinct, the new source emits a stream of photons in pairs at regulated times with "entangled," or interrelated, properties.
The photon source is similar to an ordinary semiconductor emitter, but contains a tiny, nanometer-sized quantum dot that emits the coupled photons.
Mark Stevenson, TREL researcher and lead author, said: “We discovered that only dots with a certain shape can emit photon pairs which are entangled and that the required shape can be engineered by controlling its growth process.”
The device is claimed to be important for two reasons. First, it was fabricated in a way similar to an ordinary semiconductor light emitter; second, it produced entangled photons on command.
According to Andrew Shields, head of TREL's Quantum Information Group, entangled photons could become essential components in future semiconductor and IT systems that exploit quantum effects. "A simple device for generating entangled photons will greatly accelerate these technologies, as well as stimulate new ones. Indeed, analogy with developments after the invention of the semiconductor laser suggests there may be many more applications that we have not yet even imagined.”