Posts Tagged ‘photodiode’
Counting Protons with a Fiat 500
Ok, so not really with a Fiat 500, with a avalanche photodiode. An photodiode converts light (photons) into either current or voltage. You’ve probably seen it in use if you have a light which switches on when it gets darker.
An avalanche photodiode is more sensitive compared to other semiconductor photodiodes, but are still not able to distinguish between one photon or multiple photons arriving. Andrew Shields explains how to use a standard avalanche photodiode so that it counts photons as they arrive in the article An avalanche-photodiode-based photon-number-resolving detector. “ That’s like turning a Fiat 500 into a Ferrari.“
It’s actually relatively simple, when you think about it. A photon causes a certain amount of energy to be released when it first hits the avalanche photodiode, two photons cause twice the amount of to be released. At this early stage, say Shields and friends, the avalanche current is proportional to the number photons that have struck.
The reason this is so impressive is that it reduces the cost of detecting photons down. Currently the last mile for ISPs is almost exclusively over copper, this discovery makes it cheaper to put glass fibre in your home. And as mentioned in the abstract it makes optical quantum computing more of a reality.
technorati tags: electronics, photodiode, photon
