Google claims breakthrough in quantum computer error correction
ft.com
ft.com
https://www.nature.com/articles/d41586-022-04532-4
The FT article is a bit fluffy. here are links to the paper and briefing in Nature.
> It is known in the field that, when the physical error rate of qubits is high, the probability of logical error increases with increasing system size, whereas when physical error rates are low, increasing the system size leads to the desired exponential suppression of logical error. We feel that we are currently in a ‘crossover’ regime between these scenarios, in which increasing system size initially suppresses the logical error per cycle, but would, with increasing size, later increase error rates. Therefore, it is imperative that we continue to improve both qubit performance and system scale.
So this result is not yet the major breakthrough that would be required to build a scalable quantum computer.
I look forward to hearing Scott contextualize it.
but it makes sense that they should pursue such sayings because prestigious magazines are all about 'status' and 'signaling' and what people think; specially now that technology has made their former 'logistical' contributions redundant (referring to the printing of the stuff and getting it to where it's needed) and also how the actual peer reviews are essentially volunteer labor, again because they have their prestige.
Because it’s not a statement of fact but very clearly an opinion protected by the first amendment (at least in the United States).
Trying to bring a libel or defamation case would be an expensive and losing proposition.
Anyway I think there is a role for "sexy but wrong" journals- but that role is limited to extremely competent scientists working at the state of the art of their quantitative field. I don't think anybody should take what gets published in Nature and just sort of naively share it on social media with the claim it proves/doesn't prove something. The context required to evaluate a Nature paper on its merits is absolutely enormous.
“Factual” and “humorous” aren’t opposites. I think “publishing in Nature is a strong signal that the results are wrong” is likely to be determined to be an opinion, regardless of whether you mean it serious or as a joke.
The basic dividing line the court has drawn between “factual claim” and “protected opinion” is whether the claim is objective and can be proven true or false.
In general it seems (to me, a non lawyer) that your signal claim isn’t an objective one. There’s no hard line about when a journal would be a “strong signal” vs a “weak signal” vs “no signal” about something being wrong. It’s not really a statement that can be proven to be true or proven to be false. Which is why I think it would be considered to be your opinion about Nature (even if a very serious opinion)
I suppose America is still chief imperial hegemon... imma go check myself in. bye
Don't really see the point to invoke imperial hegemony in your criticism, it just makes you sound petty.
I will say, I have a strong preference for US libel law, and aversion to UK libel law, but that’s probably mostly my cultural upbringing and familiarity speaking.
TIL "libel tourism" was a motivator for it, precisely because English libel law was too far-reaching.
https://en.wikipedia.org/wiki/Libel_tourism
> On January 1st, 2014 the Defamation Act 2013 came into force, requiring plaintiffs who bring actions in the courts of England and Wales alleging libel by defendants who do not live in Europe to demonstrate that the court is the most appropriate place to bring the action. Serious harm to an individual's reputation or serious financial harm to a corporation must also be proven. Good faith belief that a disclosure was in the public interest was made a defense.
Because studies of the replication crisis have actually borne this out. Journals with higher impact publish more results that fail replication than journals with less impact, because those results are counterintuitive and "sexy". Being first to publish such novel or unintuitive findings increases their profile/impact because they'll get cited more.
Considering that Scott works in theoretical quantum complexity theory, I highly doubt that he reviewed this experimental quantum error correction paper.
* In an error correction code, you encode a logical bit/qubit into a set of physical bits/qubits.
* Error correcting codes come in families, parameterized by integer distance d. Incrementing d, leads to a code with more physical bits/qubits, n, but also the ability to correct errors on a larger number of bits/qubits, j.
* If the error probability on each qubit is p, then on a code of size n, there will be on average n*p errors. It should be immediately clear that if p is small, then n*p<j and the code can correct errors that occur, but if p is large then n*p>j and there will be errors that the code can't correct.
* If the code corrects any physical errors that do occur, then there won't be a logical error (value of logical bit/qubit unchanged), otherwise there will be a logical error. In summary, given a p, you have to pick the right sized code from your family so that n*p<j, and you don't incur any logical errors.
* Another way of saying the same thing is that if p in your hardware becomes small enough, then as you increase your distance d, your logical error rate will go down.
These guys are claiming that their p is small enough that the distance 5 code has a smaller logical error rate then the distance 3 code, which is indeed a breakthrough (if correct). No one has done something like this before to my knowledge.
# Criticism
* The results are limited to storage errors. All they are doing is initializing the logical qubit in some initial state and repeatedly doing error-correction on it, to simulate a qubit at rest while the computation is happening elsewhere on some hypothetical other logical qubits. They have not attempted to do any experiments with applying gates to the qubits. Those will likely yield a much larger error rate. In particular, they are only testing a single logical qubit here, but the interesting gates would be two-qubit gates between two logical qubits, which are necessary to do any non-trivial computation.
* The experiment is limited to 25 cycles of error-detection. This means that their experiment shows that their device could hypothetically implement a depth ~25 circuit. As you might realize, useful circuits have depth many orders of magnitude larger, so this continues to be toy device.
The above is what immediately springs to mind, but I am sure the actual experts will soon chime in. My subjective opinion is that the technical achievements of just running the experiment are very impressive. This is a long journey to useful QCs, but this is nice milestone along the way.
This is more from personal ignorance/laziness and convenience than strong conviction: you cannot follow all areas, you have to make some choices how you spend your time, and this is one particular area that is easy to delimit. (EDIT: and if it does turn out to be a dead-end, I can be glad I made the right call.)
At times this policy has been quite hard to follow, and I may reconsider it sometime, but so far it has served me well.
Which is a well-known area in both computer science and.. quantum physics of black holes.
But that’s not what you’re saying. Instead you are saying that you don’t follow it because well, you can’t follow everything. And I agree with that. But in that case, you could go to every single HN topic and post “I don’t follow <insert topic here>, I’m just posting to tell you that I can’t follow everything. So far it has served me well to not follow everything.”
Which doesn’t seem particularly useful or contributory in any way.
However, if you work in: biology, physics, or chemistry: quantum is a frequently used word. It covers far more than QC, entanglement, coherence, tunnelling, or any other crazy bits of quantum. It forms the basis for our atomic theory of matter and has led to extraordinary engineering and science projects.
I used to be excited by DNA computing but it became clear quickly that regardless of any stated advantages of DNA computing, they were tiny compared to the modern working digital computer and the global infrastructure dedicated to improving it year after year (even after Moore's law putters out).
Ironic that writing this comment as well as reading it is considered a worthwhile time expenditure.
Same for "crypto" here :-)
The experiment being announced here is testing different ways storing 1 error corrected qubit, to show that making it bigger can make it better. On an absolute scale, that logical qubit is still not good enough. It needs to be made even bigger. And there needs to be a dozen of them instead of one. And it's barely breaking even; you want strong gains in quality from adding quantity not just minor gains. This means the underlying physical qubits still need more improvement. There's a lot to do!
Disclaimer: am on google quantum team, opinions are my own.
While reading about the actual advantages of quantum machine learning over classical machine learning something that came up was a type of error correction you can do in quantum computing that would make backpropagation faster.
Does anyone who understands this better know if this breakthrough might theoretically apply for that application (in the future, with more qubits of course)?
[0] https://en.m.wikipedia.org/wiki/Quantum_machine_learning