TO BE sure no one’s listening, you need to send your message using just one
photon at a time. That way, if anyone intercepts it you’ll know.
But producing lone photons isn’t 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’s 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’s Andrew Shields…
