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Willow, Our Quantum Chip

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Re: Willow, Our Quantum Chip

#481
post #421

In the past five years I participated in a project (with Yosi Rinott and Tomer Shoham) to carefully examine the Google's 2019 "supremacy" claim. A short introduction to our work is described here: https://gilkalai.wordpress.com/2024/12/09/the-case-against-g... . We found in that experiment statistically unreasonable predictions (predictions that were "too good to be true") indicating methodological flaws. We also fou…

I've heared claims before that quantum computers are not real. But I didn't understand it. Can anybody explain the reasoning behind the criticism? Are they just simulated?

So the basics:

- quantum physics are real, this isn't about debating that. The theory underpinning quantum computing is real.

- quantum annealing is theoretically real, but not the same "breakthrough" that a quantum computer would be. Z-wave and google have made these.

- All benchmark computations have been about simulating a smaller quantum computer or annealer. which these systems can do faster than a brute force classical search. These are literally the only situation where "quantum supremacy" exists.

- There is literally no claim of "productive" computation being made by a quantum computer. Only simulations of our assumptions about quantum systems.

- The critical gap is "quantum error correction", proof that they can use many error prone physical qubits to simulate a smaller system with lower error. There isn't proof yet that is actually possible.

This result they are claiming, is they have "critical error correction" is the single most groundbreaking result we could have in quantum computing. Their evidence does not satisfy the burden of proof. They also only claim to have 1 qubit, which is intrinsically useless, and doesn't examine the costs of simulating multiple interacting qubits.

Re: Willow, Our Quantum Chip

#482
You learn a lot by what isn't mentioned. Willow had 101 qubits in the quantum error correction experiment, yet only mere 67 qubits in the random circuit sampling experiment. Why did they not test random circuit sampling with the full set of qubits? Maybe when turning on the full 101 set of qubits, qubits fidelity dropped.

Remember macroscopic objects have 10^23=2^76 particles, so until 76 qubits are reached and exceeded, I remain skeptical that the quantum system actually exploits an exponential Hilbert space, instead of the state being classically encoded by the particles somehow. I bet Google is struggling just at this threshold and they don't announce it.

Re: Willow, Our Quantum Chip

#484
post #421

In the past five years I participated in a project (with Yosi Rinott and Tomer Shoham) to carefully examine the Google's 2019 "supremacy" claim. A short introduction to our work is described here: https://gilkalai.wordpress.com/2024/12/09/the-case-against-g... . We found in that experiment statistically unreasonable predictions (predictions that were "too good to be true") indicating methodological flaws. We also fou…

I've heared claims before that quantum computers are not real. But I didn't understand it. Can anybody explain the reasoning behind the criticism? Are they just simulated?

I think that this is now a very fringe position - the accumulation of reported evidence is such that if folks were/are fooling themselves it would now be a case of an entire community conspiring to keep things quiet. I mean, it's not impossible that could happen, but I think it would be extraordinary.

On the other hand the question is what does "real QC" mean? The current QC's perform very limited and small computations, they lack things like quantum memory. The large versions are extremely impractical to use in the sense that they run for 1000ths of a second and take many hours to setup for a run. But that doesn't mean that the physical effects that they use/capture aren't real.

Just a long long way from practical.

Re: Willow, Our Quantum Chip

#486

Earlier quoted context omitted.

Right? Does TLS1.3 have the underpinnings to use quantum-proof encryption algos? https://en.wikipedia.org/wiki/Post-quantum_cryptography https://www.microsoft.com/en-us/research/project/post-quantu... https://www.forbes.com/councils/forbestechcouncil/2024/10/09...

It seems you can get TLS 1.3 (or atlest slighty modified 1.3) to be quantum secure, but it increases the handshake size by roughly 9x. Cloudflare unfortunately didn't mention much about the other downsides though. https://blog.cloudflare.com/kemtls-post-quantum-tls-without-...

About one third of traffic with Cloudflare is already using post-quantum encryption. https://x.com/bwesterb/status/1866459174697050145

Signatures still have to be upgraded, but that's more difficult. We're working on it. http://blog.cloudflare.com/pq-2024/#migrating-the-internet-t...

Re: Willow, Our Quantum Chip

#487

Earlier quoted context omitted.

Right? Does TLS1.3 have the underpinnings to use quantum-proof encryption algos? https://en.wikipedia.org/wiki/Post-quantum_cryptography https://www.microsoft.com/en-us/research/project/post-quantu... https://www.forbes.com/councils/forbestechcouncil/2024/10/09...

Yes-ish. They're not enabled yet, but post-quantum signatures & KEMs are available in some experimental versions of TLS. None are yet standardized, but I'd expect a final version well before QCs can actually break practical signatures or key exchanges.

One third of all human traffic with Cloudflare is using a post-quantum KEM. I'd say that counts as enabled. We want that to be 100% of course. Chrome (and derivates) enabled PQ by default. https://radar.cloudflare.com/adoption-and-usage

Re: Willow, Our Quantum Chip

#489

With this plus the weather model announcement. I’m curious what people think about the meta question on why corporate labs like Google DeepMind etc seem to make more progress on big problems than academia? There are a lot of critiques about academia. In particular that it’s so grant obsessed you have to stay focused on your next grant all the time. This environment doesnt seem to reward solving big problems but paper…

I can only speak for the weather models (since it is in my domain). The answer is that the issues are much more engineering and scaling/infra issues than theoretical issues, and google is good at engineering (or attracts people that are).

Re: Willow, Our Quantum Chip

#490

Earlier quoted context omitted.

The relevant RSA break is sufficiently powerful quantum computers, which also break ECDH (actually, ECDH is easier than classically equivalent-strength RSA for quantum computers[1]), so no, you’re not fine. [1] https://security.stackexchange.com/questions/33069/why-is-ec...

I would actually expect RSA to see a resurgence due to this. Especially because you can technically scale RSA to very high levels potentially pushing the crack date to decades later than any ECC construction. With the potential that such a large quantum computer may never even arrive. There are several choices with scaling RSA too, you can push the primes which slows generation time considerably. Or the more reasonab…

If you don't mind a one terabyte public key. https://eprint.iacr.org/2017/351.pdf
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