Physicists in Germany have created a new optical device that can absorb exactly one photon. They say that this device, which exploits the physical properties of giant micron-sized atoms known as Rydberg atoms, could be used in optical quantum computing networks of the future.
Sebastian Hofferberth of the University of Stuttgart explains that the device first behaves like a dark sunglasses lens, but once it absorbs its first photon it becomes transparent to light. One important application of the device, says Hofferberth, could be to absorb single photons from a quantum network. Another potential application is a precise photon counter, which could be made by putting a number of the devices in series.
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