Scientists at Toshiba and Cambridge University have used an advanced photodetector to extract weak photons from the torrents of light pulses carried by fiber-optic cables, in a technique that offers a less expensive way to ensure the security of the Internet. Based on quantum physics, the approach would make it possible to safely distribute secret keys necessary to scramble data over distances up to 56 miles.
Although several quantum key distribution systems are commercially available, they rely on the need to transmit the quantum key separately from communication data, often in a separate optical fiber, which adds cost and complexity, says Toshiba Research Europe's Andrew J. Shields. The system developed by Toshiba and Cambridge sends the quantum information over the same fiber, but isolates it in its own frequency. "We can pick out the quantum photons from the scattered light using their expected arrival time at the detector," Shields says. "The quantum signals hit the detector at precisely known times — every one nanosecond, while the arrival time of the scattered light is random."
Weaving quantum information into conventional networking data will lower the cost and simplify coding and decoding data.
From The New York Times
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