A device that counts photons will secure optical data networks from prying eyes

Commercialization of quantum cryptography is the wave of the future, and always will be. ID Quantique and MagiQ Technologies have been in the field for a while. Their customers are primarily university researchers. That, in itself, says something to potential speculators.Not only is quantum communication limited to short distances (~100 km), it is excruciatingly slow. One kilobit/sec is considered fast. While the short distances mean quantum communication is best suited to high-density metro markets (NYC, DC, London), the slow speed means that potential customers could do better with a courier carrying a DVD and an assault rifle.Quantum communication can be used to exchange keys for booting up a high-speed, albeit conventional, cryptography system. However, the risk of eavesdropping would be the same as today.Finally, as Bruce Schneier has commented, quantum cryptography does not addresses more serious security problems, such as weak passwords.

Sirs:

Combine this with the photos of a light beam as reported recently in a science journal, and soon we'll have clear photos of the angels dancing on the pin head.

Seriously, a marvelous achievement.

Ignore this grouchy old village idiot.

Jacomus

Ok someone needs to explain this article in simple english. Something without the word quantum involved would be appreciated.

I believe about eighteen months ago there was an experiment where a photon emiter had a blocker to stop the photon. What happened was that a photon hit the reciever at 1.2 times the speed of light. They have now got the device too get up to 1.8 times the speed of light. This event was timed using a micro wave transmitter sending a signal to a reciever at the exact same time. They believe it was due to quatom tunneling that a photon came from "somewhere" too hit the reciever. Music was sent using the device, so one might say that the first faster then light data has been sent. PRETTY FAR OUT stuff I should say.

MARK1950

Strictly speaking, this is teleportation, not a quantum repeater. If these detectors work with telecom frequencies with low noise, this is greta news!

a report on the construction of the device is at arxiv.org as a free download.http://arxiv.org/ftp/arxiv/papers/0807/0807.0330.pdfAdding a shifted negative of a signal to the signal itself is a tried and true technique. Using it at the avalanche inception is the tour-de-force of this technique.