Quantum Random Numbers

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."

Comments

Or just use excel

[stating_the_obvious]

A few months ago some guy generated random numbers firing lasers at diamonds; and now we've got quantum light. Maybe someone could explain how randomness varies in non-random ways...

Re:Or just use excel

[Joce640k]

Didn't SGI solve this problem ages ago...

Re:Or just use excel

[TheCarp]

Yet from the wiki page:
It is covered under U.S. Patent 5,732,138, titled "Method for seeding a pseudo-random number generator with a cryptographic hash of a digitization of a chaotic system."

I don't believe it ever became a product... and was cumbersome to setup. Hard to justify a lava lamp display in a data center, and god forbid you need multiple sources in one DC say, on every machine)

One thing I worry about with devices like this is failure mode. if it can be made totally solid state, I would think it could be setup analogously to the way solid state relays are (with an emiter and detector in a small package).... but.... if it failed such that its numbers stopped really being random.... in what ways will it be able to detect this? (not just theoretically, but in real designs). Its great if you can get an error, but, it could be prolblematic if it just starts streaming highly repetitive numbers.

site is slashdotted..so...

[Anonymous Coward]

..feel free to use these...

1 1 1 1 1 1 1 1 1 1 1 1

Re:site is slashdotted..so...

[Anonymous Coward]

I'll only use them if you can assure me that they were chosen by fair dice roll..

There's no such thing as random

[ShieldW0lf]

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.

Re:There's no such thing as random

[Anonymous Coward]

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

Re:There's no such thing as random

[Anonymous Coward]

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.

Re:There's no such thing as random

[Surt]

There's no proof of that. That's a commonly held belief, but that doesn't make it true. The bottom line is that we don't know whether there is any randomness in the universe, and there is certainly considerable evidence that there might be.

Re:There's no such thing as random

[ShieldW0lf]

The fact that there was a singularity in the first place makes it pretty obvious that entropy does not only go one way. Abiogenesis will eventually be accepted as fact, and this will provide strong evidence that the "heat death of the universe" hypothesis is wrong.

I wrote a rambling essay that I think relates and threw it in my journal for the trolls to rip apart... maybe it will provoke something.

http://slashdot.org/journal/281071

So much for random

[bulldog060]

Just keeps spitting out 503 ... >.>

No thanks

[Anonymous Coward]

The generation of random numbers is too important to be left to chance.
- Robert R. Coveyou, Oak Ridge National Laboratory

Re:dead link

[game kid]

The site and its images randomly (appropriately enough) bobble between working and 503 at the moment. Not quite down, but taking heavy fire.

Raas!?

[turbidostato]

Randomness as a Service?

I don't know if out will work, but I know it certainly shouldn't.

In two words: MiM attack.

Re:Raas!?

[rapidmax]

The random service alone as cryptographic source raises questions about thrust. But if you use it as an additional source to mix into you entropy pool, it won't hurt and probably improve the quality and data rate of your random source.

~Andy

Re:Quantum

[jawtheshark]

In this case, it doesn't matter. Random number generation is in itself interesting and a very important part of computer science... or better said, the problem that with a finite state machine, like a computer, we cannot generate truly random numbers. Computers can generate pseudorandom numbers, but they are only random within the constraints set, are repeatable and will have a periodicity. Getting "true" random numbers only is possible from physical processes.

There have been several articles about random number generation on slashdot. On the top of my head, random numbers generated from a lava lamp, or from a CCD with a (disassembled?) smoke detector (which contains Americum, a radioactive element). Let's just say that random numbers are interesting unto themselves. That's they're generated by quantum fluctuations is just an added bonus.

Radioactive decay

[mbone]

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.

Re:Radioactive decay

[rapidmax]

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.

Having build my own random generator I can confirm this discrepancy between theory and practice. You have to be very cautious to eliminate externals noise and oscillation of the random source. As it's not possible to measure the true randomness but only guess it, additional filtering like bias elimination and mixing may improve the entropy, but may be still not true random.

Re:dead link

[KiloByte]

But does the decision whether to return a 503 or data use true randomness?

Re:dead link

[dna_(c)(tm)(r)]

The site and its images randomly (appropriately enough) bobble between working and 503 at the moment. Not quite down, but taking heavy fire.

Probably the cleaning lady using the left beam of light to read the instructions on the detergent bottle, thereby generating a whole string of identical 503 numbers.

There is no need for this new method at all

[gweihir]

Zener-noise at 5V6 or NPN transistor EB noise is already about half quantum effect noise. Just use that, plenty of recipes on the web. Cost is at a few USD/EUR for the raw generator and you can get it as an USB stick.

Examples:
http://www.cryogenius.com/hardware/isarng/
http://www.tonbandstimmen.de/evpmaker/random-bit-generator/index_e.htm
http://www.entropykey.co.uk/

Seems to me the quantum folks are getting a bit desperate to prove they actually are doing something worthwhile.

Re:dead link

[j00r0m4nc3r]

I guess the cleaning lady uses a quantum vacuum

My RNG algorithm...

[Iniamyen]

I tell my dog to go get a toy. I've preassigned a numerical value between 1 & 10 to each of her toys. Whichever one she brings me, I cube the resulting number, and then divide by today's date (1 thru 31), and then floor the result. I get my yellow pages and turn to this page. I take the time of day as a percentage of 24-hour time (so 0700 would be 29.2%) and go that percentage down either the left or right column on that page, depending on the phase of the moon (left column for waxing, right column for waning.) Whichever phone number is there, I call. I then ask whoever picks up to think of a number.

Re:My RNG algorithm...

[atisss]

As the rest of variables are known for each individual point in time, your choice is limited by 1/10 preference of dog (your precision to measure percentage in page is cancelled out by fact that dog probably has some favourite toys is probably ).

Given call centre with 50 employees I could constantly dial to the numbers you have chance to choose and ask if you have called and what number have the person told you. That would give 2/3 advantage to find out the number (If the person would lie, or hangup, he probably wouldn't told you the number in first place).

So, that's not random

Re:dead link

[jamiesan]

Naturally, she abhors the vacuum.

I use government employment numbers

[gestalt_n_pepper]

If not random, they at least have a minimal correlation with reality.

Re:A cheap non-quantum option

[canajin56]

How "very random" do you need, that a Mersenne Twister is not good enough, but an untested signal is? And if you only looked at the 1 bit word mean, you basically didn't test it at all. If you don't care about specifics, you can just use the Testu01 suite of tests. If you care about specifics and want to do your own tests...you should do the same bias test for various word lengths. So besides making sure the 0 and 1 appear about 50% of the time, you should make sure that 00,01,10,11 appear about 25% of the time, 000,001,etc are all uniform for 3 bit words, and so on until at least several hundred bit words (yes, it will take you a long time to sample enough words!) Besides those simple "fair dice" tests, you can also pick a dimension, (2 or more) and sample a lot of points (using whatever bit words you like) and then find the minimum distance between two points. With repeated tests this minumum distance should follow an exponential distribution, with the parameters describing that distribution depending on the range of possible values and the number of dimensions. Similarly, if you treat your n bit words as floats from [0,1) (by dividing by 2^n), then sampling a large number and adding them together should get you a normal variable, where the mu and sigma depend on n and how many you are adding together. There's also a 'pigeon hole' test where you have 2^n bins and sample n bit words and put them in the bin, and then take the maximum occupancy. Again, statistically this value should have a known distribution and you can test against that. A related one is called a "parking lot" test, where you sample in 2 dimensions and treat points as circles of some radius, and you only place a circle if it doesn't overlap with other circles already placed. After 10,000 samples you should have less than 10,000 placed, and the number you actually placed should be normally distributed, with the mu and sigma depending on the size of the lot, the number of attempts, and the radius of the circles used. There are plenty of such tests. They all revolve around using your generator to simulate a simple statistical system where the distribution of the result is known by you, so you can see how consistent your repeated simulations are with the expected distribution. A 1-bit mean test is just simulating coin tosses, while a 2-bit mean test is simulating 4 sided die tosses, etc.

But a Mersenne Twister does quite well on Testu01, so you have to ask yourself why a software generator can't possibly be sufficient.

As for the mechanical "what's wrong" side of things, if you don't know the physical mechanism, you can't know what conditions are required for your tests to remain valid. Where is the line noise coming from? Just noise from the physical components, or is there a radio wave factor? Will a new tower broadcasting alter the behavior of the noise in a meaningful way? What about wifi devices? I know of sound cards that pick up the signal sent when a cellphone rings so you can tell moments before it actually rings. (You can get a TARDIS for your keychain that lights up when a nearby cellphone is being rung, which works by the same mechanism but on purpose).

Re:dead link

[kulnor]

Note that you can readily buy your own USB or PCI quantum number generator generator: http://www.idquantique.com/true-random-number-generator/products-overview.html

Re:What if

[gestalt_n_pepper]

Well, try not to introduce too much noise or they'll shut us off. So, please just sit there. Quietly.