God, said Albert Einstein, does not play dice. It is a known, but revealing declaration: for the famous physicist, the real random – and the new quantum framework which threatened to rewrite the rules of the universe again – was an anathema.
Well, no offense in Einstein, but he was wrong on this one. Not only has quantum theory resisted the test of time, but it turned out to be useful in everything, computer science, biology, optics, living room games. And now, in a rather poetic turn, it can be about to revolutionize the dice throws.
A random problem
“The unpredictability of random numbers is fundamental both for digital security and applications that distribute resources fairly”, begins a new article by researchers from the University of Colorado Boulder and the National Institute of Standards and Technology, or NIST. It’s not bad, but here is the problem: a real random? It is quite impossible to achieve in the real world.
“The real randomness is something that nothing in the universe can predict in advance,” said Krister Shalm, a physicist Nist and one of the authors of the article, in a statement on Wednesday. This excludes the “roller of dice” which theoretically embodies the random character, and it – perhaps surprisingly – prevents a lot from these “generators of random numbers” which boast of various computers.
There is a way to get around this obstinate predictability, and it is to go Quantum. Take the double slit experience, for example – a fundamental demonstration of quantum physics, in which a beam of light is intended for a solid screen with two slits cut there, leading to a model of interference on a screen beyond. However, it is impossible to predict precisely what this interference scheme is impossible to predict – unlike classical mechanics, the location of the nature of any given particle is probabilistic, rather than deterministic, of nature.
In simple terms: the quantum world is the place where we find a real random – and it can be proven, more or less, using a configuration fairly similar to this same double slit experience. The key is in what is called a bell test: essentially, you perform an experience, measure the results and delete all the bits which can be allocated to conventional level conditions. Stay correlations that remain? These come almost certainly from quantum physics.
Use these on -board correlations and “you can transform this into the best generator of random numbers that the universe allows,” said SHALM. But here is a question: how would you know if you understood correctly?
A quantum check
This is a simple question, with a complex solution: given a selection of so-called “random” numbers, how would you check them? After all, it is quite easy to generate sequences that look Random, but are not – computers do it all the time. Likewise, the real random rarely peeks human radars as such. How do you explain this?
Part of the answer is again given by the bell test – or rather an inflated version of it, known as flawed bell test. It works by observing the correlations between pairs of distant photons that have been specifically configured to eliminate all the factors that could accidentally imitate the effects of quantum mechanics, such as sampling or lower interference within the system.
In fact, NIST researchers used exactly this technique to generate certifiable random numbers in 2018. “Our quantum source and our protocol are like a failure”, the mathematician Nist Peter Bierhorst boasted at the time. “We are sure that no one can predict our figures.”
“Something like a reversal of money may seem random, but its result could be predicted if one could see the exact path of the medal when it falls,” said Bierhorst. “The quantum random character, on the other hand, is real random. We are very sure that we see a quantum random because only a quantum system could produce these statistical correlations between our choices of measurement and our results. »»
https://www.youtube.com/watch?v=W9HRTMQ0VOE
It looks like a perfect solution, but it is not without problems. It is highly intensity, both to install and run. More worrying, this is only a source – which means that if it was intercepted by a bad hypothetical actor, determined to program it with secretly predictable results, there would be really no way to say it.
What you need, the physicist Nist and co-author of paper Gautam Kavuri told Science News, is “a really paranoid way to make sure that things are really random”. Something, he says, that “you would need to communicate faster than the speed of light to be able to travel”.
And now they just have the thing.
Democratize unpredictability
The strength, they say, comes in figures. With their new Curby tool, researchers from the NIST and the University of Colorado put this aphorism in practice.
“We really wanted to withdraw (the) laboratory experience and transform it into a useful public service,” said Shalm. Curby – that is to say the random tag of the University of Colorado – the fact by generating random numbers through the methods refined by the NIST on a really remarkable scale: about 15 million times on a single minute, creating a large basin of results which is then sent to the University of Colorado Boulder for treatment. The result, just under seven minutes later, is 512 random bits of binary code – the equivalent of 2512 (a number of 155 figures long) possible random numbers. It is, the NIST declares: “The best reversal of the universe of the universe”.
But we haven’t finished yet. Generating the numbers is one thing – but checking them? This is where innovation comes into play.
“The solution, a protocol that we call Twine, is based on the concept of intertwining different hash channels to form a hash graph,” said the authors in the pre -printed version of their article. It is essentially an extra -large blockchain: a list of data ordered by secure cryptographically, for which the addition of new information – as a single stage of the procedure for generation of random numbers – is “chopped” with the previous block. This is particularly useful for things like this, because, as the team points out, “trying to change a data block without detection would require rewrite the whole chain after this point”.
Imagine that, but … bigger. See, Curby takes out this blockchain laterally also: “To prevent (…) the falsification of all the blocks on a single chain, the Twine protocol allows a block to include blocks of blocks of several channels operating by different parts, creating a directed acyclic graph”, wrote the team. “If a party tries to falsify its published files, it can be detected by other parts, because the hashs recorded on their channels will no longer be consistent.”
“In other words, for a bad actor to be detected, they must surreptitiously rewrite their own hash chain, but also to all the others that are connected,” explains the newspaper. “As the number of independent parties in the network increases, such an action becomes more and more difficult.”
So how many people are involved in this network? Well … as much as you wish, in fact: Curby disseminates random numbers via a website to which any user can access to check the data. It is “a tapestry of trust,” said Jasper Palfree, a research assistant on the project at the University of Colorado Boulder – a “network of chance to which everyone contributes, but no individual control”.
For a tool presented as a way to select the jury service or public lotteries, this large open source collaboration network may be appropriate. And the fact that it is also a new solution to a complex quantum physics problem? It’s just the icing on the cake.
“I wanted to build something that is useful. It is this cool thing that is the point of fundamental science,” said Kavuri. “Nist is a place where you have this freedom to continue ambitious projects but which will also give you something useful.”
The study is published in Nature.
