杏吧原创

TO BE sure no one鈥檚 listening, you need to send your message using just one
photon at a time. That way, if anyone intercepts it you鈥檒l know.

But producing lone photons isn鈥檛 easy. Optical techniques are cumbersome, so
researchers at Toshiba Research Europe in Cambridge have made a tiny
semiconductor device called a quantum dot, that spits out a single photon each
time it鈥檚 jolted by an electrical pulse. A report on their work will appear in a
future issue of Science.

So far the device has only been tested at temperatures near to absolute zero,
but Toshiba鈥檚 Andrew Shields says future versions should work up to around 200
kelvin (鈭�73掳C). 鈥淲e think it鈥檚 very practical because it鈥檚 an
adaptation of a conventional LED,鈥� he says.