Researchers at the Max Plank Institute for Optical Physics have developed a device that generates true random numbers. This development is very important for encrypting data, such as bank transactions, and for the simulation of complex processes, such as economic market models and climate change model based on probabilistic calculations.
Sequences of random numbers produced by computer programs are never entirely random. They typically repeat themselves after a (long) period or allow certain patterns to be detected if a sufficient large quantity of numbers is available. However, truly random events occur in the realm of quantum mechanics. For example, half photons occur in a vacuum or in absolute darkness, and they produce fully random quantum noise.
The newly developed random number generator, which makes use of this quantum noise, consists of a powerful laser whose beam is divided into two separate beams by a beam splitter. During this process the laser light is mixed with the quantum noise. Detectors are located at the outputs of the beam splitter, and they convert the laser beams into electrical signals. When these two signal are fed into a differential amplifier, the laser component is cancelled out and the quantum noise is left in the output signal. This noise has a Gaussian probability distribution, which is divided into areas of equal size, and numbers are assigned to these areas. The sequence of numbers resulting from the quantum noise is fully random.
The results of the research were published on 29 August 2010 in the online edition of Nature Photonics.
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