Needless to say, the researchers did not decipher this quantum mechanics puzzle to pass the time during their coffee breaks. "True random numbers are difficult to generate but they are needed for a lot of applications," says Gerd Leuchs, Director of the Max Planck Institute for the Physics of Light in Erlangen. Security technology, in particular, needs random combinations of numbers to encode bank data for transfer. Random numbers can also be used to simulate complex processes whose outcome depends on probabilities. For example, economists use such Monte Carlo simulations to predict market developments and meteorologists use them to model changes in the weather and climate.
There is a good reason why the Erlangen-based physicists chose to produce the random numbers using highly complex vacuum fluctuations rather than other random quantum processes. When physicists observe the velocity distribution of electrons or the quantum noise of a laser, for example, the random quantum noise is usually superimposed by classical noise, which is not random. "When we want to measure the quantum noise of a laser beam, we also observe classical noise that originates, for example, from a shaking mirror," says Christoffer Wittmann who also worked on the experiment. In principle, the vibration of the mirror can be calculated as a classical physical process and therefore destroys the random game of chance.
"Admittedly, we also get a certain amount of classical noise from the measurement electronics," says Wolfgang Mauerer who studied this aspect of the experiment. "But we know our system very well and can calculate this noise very accurately and remove it." Not only can the quantum fluctuations enable the physicists to eavesdrop on the pure quantum noise, no one else can lis
|Contact: Dr. Christoph Marquardt|