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Willow, Our Quantum Chip

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Re: Willow, Our Quantum Chip

#551

Post by rhubarbtree »

ozzsama wrote: post #491
rhubarbtree wrote: post #259

Earlier quoted context omitted.

This is correct. I worked in quantum research a little.

Dear rhubarbtree, I'm very sorry to admit it but I'm too lazy to read the entire discussion in this thread. Could you please tell me, a mere mortal, at which point the humanity should start worrying about the security of asymmetric encryption in the brave new world of quantum computing?

Funny turn of phrase, but you probably need 20 million physical qubits (or at least you did a few years ago, this number may have dropped somewhat) to do anything significant. I don't think we can be confident we'll get there any time soon.

Re: Willow, Our Quantum Chip

#552

Post by dexterdog »

mrguyorama wrote: post #518
dexterdog wrote: post #462

Earlier quoted context omitted.

How would she not survive on YouTube? Would they block her posts if she didn't use a misleading title and thumbnail (shout-out to dearrow for those who despise this practice)?

>Would they block her posts if she didn't use a misleading title and thumbnail So, the way youtube works is that every single creator is in an adversarial competition for your attention and time. More content is uploaded than can be consumed (profitably, from Youtube's point of view). Every video you watch is a "victory" for that video's creator, and a loss for many others. Every single time youtube shows you a scree…

This is in a world where people view youtube through the interface which is obviously most people. I have feeds that I subscribe to and some of them are must-see for me, so no matter what they use as their bait I am watching it. Fortunately there exists smarttube, dearrow and sponsorblock for people like me who just want to watch the stuff they've subscribed to and not whatever advertises the best.

Re: Willow, Our Quantum Chip

#553

Post by movpasd »

tsimionescu wrote: post #413
movpasd wrote: post #305

Earlier quoted context omitted.

There are compelling arguments to believe in the many-worlds interpretation. No sign of a Heisenberg cut has been observed so far, even as experiments involving entanglement of larger and larger molecules are performed, which makes objective-collapse theories hard to consider seriously. Bohmian theories are nice, but require awkward adjustments to reconcile them with relativity. But more importantly, they are philoso…

I think the key point that makes the quoted statement sciencey gibberish is that the Many Worlds Interpretation is just that - an interpretation. There is no way to prove or disprove it (except if you proved that the world is not actually quantum mechanical, in which case MWI might not be a valid interpretation of the new theory). Saying "this is more evidence for MWI" is thus true of any quantum mechanical experimen…

I think the point about it being unscientific is completely fair, as far as a press release aiming to appear scientific is concerned.

However, I also think there is a tendency among well-educated people in physics to dismiss philosophical questions out of hand. It's fair enough when the point is "let's focus on the physics as it's hard enough", but questions of interpretation have merit in their own right.

Re: Willow, Our Quantum Chip

#554

Post by JanisErdmanis »

JanisErdmanis wrote: post #77
vessenes wrote: post #18

I’m a quantum dabbler so I’ll throw out an armchair reaction: this is a significant announcement. My memory is that 256 bit keys in non quantum resistant algos need something like 2500 qubits or so; and by that I mean generally useful programmable qubits. To show a bit over 100 qubits with stability, meaning the information survives a while, long enough to be read, and general enough to run some benchmarks on is some…

The required number of qubits to execute Shor’s algorithm is way larger than 2500 qubits as the error ceiling for logical qubits must decrease exponentially with every logical qubit added to produce meaningful results. Hence, repeated applications of error correction or an increase in the surface code would be required. That would significantly blow up the number of physical qubits needed.

Well, this is embarrassing. I just realised I had wrongly interpreted the result in [1]. I made an error on how Shor's algorithm encodes the numbers, wrongly assuming that numbers are encoded into quantum state space, which is 2^(2^n), where instead, there is one bit encoded into one qubit, which is also more practical.

The result shall be interpreted directly with the error rate for logical qubits to decrease as ~n^(-1/3). This, in turn, means that factorisation of a 10000-bit number would only require an error rate of 1/10th of the number of the logical qubits for a 10-bit number. This is practical given that one can make a quantum computer with around 100k qubits and correct errors on them.

On the other hand, a sibling comment already mentioned the limited connectivity that those quantum computers now have. This, in turn, requires a repeated application of SWAP gates to get the interaction one needs. I guess this would add a linear overhead for the noise; hence, the scaling of the error rate for logic qubits is around ~n^(-4/3). This, in turn, makes 10000-bit factorisation require a logical error rate of 1/10000 that of 10-bit number factorisation. Assuming that 10 physical qubits are used to reduce error by order, it can result in around 400k physical qubits.

[1]: https://link.springer.com/article/10.1007/s11432-023-3961-3

Re: Willow, Our Quantum Chip

#555

Post by valval »

sizzle wrote: post #255
vessenes wrote: post #18

I’m a quantum dabbler so I’ll throw out an armchair reaction: this is a significant announcement. My memory is that 256 bit keys in non quantum resistant algos need something like 2500 qubits or so; and by that I mean generally useful programmable qubits. To show a bit over 100 qubits with stability, meaning the information survives a while, long enough to be read, and general enough to run some benchmarks on is some…

How long until this can derive a private key from its public key in the cryptocurrency space? Is this an existential threat to crypto?

This is the same as climate change. Something might happen sometime in the future.

Re: Willow, Our Quantum Chip

#556

Post by tobias2014 »

killerstorm wrote: post #160
jawns wrote: post #8

> It lends credence to the notion that quantum computation occurs in many parallel universes, in line with the idea that we live in a multiverse I see the evidence, and I see the conclusion, but there's a lot of ellipses between the evidence and the conclusion. Do quantum computing folks really think that we are borrowing capacity from other universes for these calculations?

Everett interpretation simply asserts that quantum wavefunctions are real and there's no such thing as "wavefunction collapse". It's the simplest interpretation. People call it "many worlds" because we can interact only with a tiny fraction of the wavefunction at a time, i.e. other "branches" which are practically out of reach might be considered "parallel universes". But it would be more correct to say that it's jus…

This might turn into a debate of defining "simplest", but I think the ensemble/statistical interpretation is really the most minimal in terms of fancy ideas or concepts like "wavefunction collapse" or "multiverses". It doesn't need a wavefunction collapse nor does it need multiverses.

Re: Willow, Our Quantum Chip

#557

Post by detdet111 »

movpasd wrote: post #305
wasabi991011 wrote: post #35

Earlier quoted context omitted.

I was also really taken aback by this quote. I have no idea who put it there, but I can assure you the actual paper contains no such nonsense. I would have thought whoever writes the google tech blogs is more competent than bottom tier science journalists. But in this case I think it is more reasonable to assume malice, as the post is authored by the Google Quantum AI Lead, and makes more sense as hype-boosting buzzw…

There are compelling arguments to believe in the many-worlds interpretation. No sign of a Heisenberg cut has been observed so far, even as experiments involving entanglement of larger and larger molecules are performed, which makes objective-collapse theories hard to consider seriously. Bohmian theories are nice, but require awkward adjustments to reconcile them with relativity. But more importantly, they are philoso…

MWI or Parallel Worlds is an interpretation of QM, it is one of the 15-20 major interpretations of QM. Nothing at all wrong with MWI. Sean Carrol speaks kindly towards WMI and I have tended to agree with his views over the years. I don't see any wild claims being made that would warrant a major reaction, but I would agree Willow's results are so impressive that it should lead one to consider at minimum that it counts as evidence in favor of the WMI. I don't see how this doesn't count as evidence for MWI.
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