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Perfect Randomness Realized For the First Time

Slashdot
1 month 1 week ago
ETH Zurich researchers say they have generated certified "perfect randomness" for the first time by using a quantum Bell-test setup with two entangled superconducting chips connected by a 30-meter cooled link. "In the long term, this work could play a similar role in digital security as atomic clocks do for timekeeping: a physically certified source of randomness that other systems can rely on," reports Phys.org. "Possible applications range from the encryption of sensitive communications and digital identities to public randomness services for lotteries and blockchain applications." From the report: They call their method randomness amplification. "This was made possible by an improved so-called Bell-Test with simultaneously high quality and high data rate," says [Renato Renner and Andreas Wallraff]. He and his coworkers use a complex setup that consists of two superconducting chips, which they cool down to very low temperatures close to absolute zero. Each chip represents a quantum bit or qubit, which can take on the states "0" or "1" or any arbitrary superposition of these states. A 30-meter-long tube, which is also cooled down, connects the two chips. Microwave photons can fly back and forth between them, thus creating quantum mechanical entanglement. This means that a quantum measurement on one qubit, which randomly yields the values "0" or "1," influences automatically and at a distance whether "0" or "1" is measured on the second qubit. The separation of 30 meters ensures that, during the measurement, even at the speed of light, no information can be exchanged between the qubits. This would disturb the perfect randomness. Wallraff and his team made the choice of the exact type of measurement (or "measurement basis" in technical jargon) on the two qubits depending on an imperfect random number generator. Renner's coworkers could then amplify the randomness of the measurement results further using a special algorithm. "The resulting sequence of zeros and ones is now really perfectly random, and we can even certify that," says Renner. He likens this result to crossing a ridge: "The technical improvements allowed us, for the first time, to create random numbers that will remain perfectly random for all eternityâ"no matter what analytical methods are used to assess their randomness." The findings have been published in the journal Nature.

Read more of this story at Slashdot.

BeauHD

CodeSOD: What Condition is This

The Daily WTF
1 month 1 week ago

Untodesu sends us this submission, with this comment:

Literally no idea what kind of drugs the guy was taking but nonetheless we've rewritten it to be just a two-liner

Well, that doesn't tell us a lot about what to expect from the code, but let's take a look.

QStringList TableViewAssembly::parametersFilter(ProbePart::Type type, int pos, QList<ProbePart> probeDesign) { QString to, from; if(pos == -1) { if(probeDesign.length() == 0) { to = "*"; from = "AutoJoint"; } else { to = probeDesign.at(0).fromMounting();; from = "AutoJoint"; } } else if(pos == 0) { if(probeDesign.length() == 1) { if(probeDesign.at(pos).type() == ProbePart::Type::Stylus) { to = probeDesign.at(pos).fromMounting(); from = "*"; } else { to = "*"; from = probeDesign.at(pos).toMounting(); } } else { to = probeDesign.at(pos + 1).fromMounting(); from = probeDesign.at(pos).toMounting(); } } else if(pos == probeDesign.length() - 1) { if(probeDesign.at(pos).type() == ProbePart::Type::Stylus) { if(probeDesign.length() <= 1) { from = "*"; to = probeDesign.at(pos).fromMounting(); } else { from = probeDesign.at(pos - 1).toMounting(); to = probeDesign.at(pos).fromMounting(); } } else { from = probeDesign.at(pos).toMounting(); to = "*"; } } else { from = probeDesign.at(pos).toMounting(); to = probeDesign.at(pos + 1).fromMounting(); } return { to, from }; }

QStringList andQList tell me that this is a Qt-based application. The goal of this function seems to be to take some inputs about a "probe part" and construct a pair of strings. Let's trace through it.

Let's just walk through the conditions, quickly, without worrying too much about the inside. We look at pos, and check for three cases: either pos is -1, 0, or probeDesign.length() - 1.

Inside each of those branches, we also check the length of the list, testing if it contains no elements, exactly one elemnet, or more than one element. We also check if the part in question is a stylus.

With that in mind, let's see if we can summarize the conditions here. If pos == -1, we do some automatic stuff, using the first element in the list if there is one. If pos == 0 and there's exactly one element in the list, we grab the first element and link it to * (the to/from order depends on the stylus question). If there's more that one element in the list, we pair the current pos with pos+1; notably, in this branch, pos is definitely zero. If pos is the last element in the list, we follow the same logic, but pair with pos-1, with a side branch for checking against the length of the list.

It's all bounds checking. That's all this code is. Bounds checking that's gotten out of hand. The main branch here is actually the final else: that's where most of the code is going to pass through. All the other branches are just handling edge cases. Literal edge cases, as in "the edge of the list".

Untodesu didn't supply the two line version, but based on the fact such a version exists, I also suspect that many of these branches weren't actually used. Or, at least, based on the actual business rules, could be combined.

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Remy Porter