scipaUsing lasers for better random numbers
December 31st 2008 05:57
Random numbers are incredibly important to the information age, used for cryptography and statistics. Currently, your computer generates random numbers psuedo-randomly, by taking the quickly-chaning last digits of the computer's internal clock, which, to you, seem random.
This breaks down if you start picking random numbers at precise intervals.
There are other ways, such as using the radioactive decay of particles, but this delivers random numbers quite slowly.
An interesting way to generate huge numbers of random numbers has been shown with a semiconductor laser, as reported in Nature Photonics, courtesy of Physorg.
They describe the process: using feedback to drive the laser into an unstable region, causing it to fluctuate wildlly. The unstable output is detected with a photodetector and then turned into a digital signal with an ADC.
Sounds simple, right? If only I had thought of it, first...
"The scientists, from Takushoku University, Saitama University, and NTT Corporation, all in Japan, achieved random number rates of up to 1.7 gigabits per second (Gbps), which is about 10 times higher than the second-best rate, produced using a physical phenomenon. They report this result in the December issue of Nature Photonics."
Using physical processes to generate random numbers is preferred over software implementations, as the random numbers fall closer to ideal randomness. While computer sources might seem random to the human eye, when statistically analyzed, they often fall short, showing trends or predictable behaviour.
Random.com claims to give you true random numbers by using atmospheric noise as the source of the numbers, and gives this service for free on the net... here's a couple of random integers.
*this image is from OKI
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