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Quantum Random Numbers

Posted by Soulskill on from the randomly-kills-cats dept.

tqft writes "What the world needs is more truly random sources of numbers. Researchers from Australian National University have found a brilliant way to make one: 'We do this by splitting a beam of light into two beams and then measuring the power in each beam. Because light is quantised, the light intensity in each beam fluctuates about the mean. Those fluctuations, due ultimately to the quantum vacuum, can be converted into a source of random numbers. Every number is randomly generated in real time and cannot be predicted beforehand.' So if you need some really random numbers, just use their generator service."

4 of 167 comments (clear)

  1. There's no such thing as random by ShieldW0lf · · Score: 4, Interesting

    The quest to find random numbers is the quest to entangle our locality to ever more distantly related things in weirder and weirder ways... which, if you ask me, is far more interesting to think about.

    --
    -1 Uncomfortable Truth
    1. Re:There's no such thing as random by Anonymous Coward · · Score: 4, Interesting

      There is no such thing is the "collapse" of the wavefunction. The observer just gets entangled with the experiment.

    2. Re:There's no such thing as random by Anonymous Coward · · Score: 4, Interesting

      Well, not so fast...

      The modern view of quantum mechanics is that the wavefunction never collapses. This isn't purely a matter interpretation (as many people claim): theoretical work over the last ~20 years on decoherence has shown that you can explain everything in QM with a deterministic wavefunction and no ad-hoc collapse axiom. Experimental work has been demonstrating quantum superposition of ever-large systems: there is no experimental evidence for collapse, which suggests that arbitrary large systems (cats, people, galaxies, the entire universe) can be in superpositions. Of course, when you're 'inside' a superposition, you cannot get information from the other branches. Thus the simplest available theory that fits experimental data is consistent with the Everett ('many-worlds') interpretation.

      In this paradigm, the evolution of the total wavefunction is deterministic and there is no global randomness. There is randomness at the level of the individual observer, since they lack the information/correlations necessary to probe other branches of the wavefunction. Whether or not you consider this 'true randomness' or just 'ignorance randomness' is as much a definitional and philosophical question as anything.

  2. Radioactive decay by mbone · · Score: 3, Interesting

    This was done using radioactive decay to generate random numbers (i.e., something like counting geiger counter clicks), I believe first in the 1950's.

    I also seem to remember that the first units weren't entirely random, due to dead times in the counters or something similar. Random in theory does not mean random in practice, and I am not sure I would trust a billion dollar deal relying on a one-time-pad generated by the ANU quantum random number generator, at least until it had been through a lot of testing.