Ask HN: Are quantum-ready co’s peddling snake oil?

https://news.ycombinator.com/item?id=29620086

by PeterWhittaker • 5 years ago

8 6 5 years ago

news.ycombinator.com

The premise of quantum-ready companies is to prepare their customers for the moment quantum computing breaks current cryptography. For example, RSA is dependent on factorization being computationally hard, but Shor’s Algorithm would provide fast factorization on sufficiently powerful quantum computers.

OK. But consider that some theorists make a direct link between quantum computing and non-locality ([1], [2]) while others ([3], [4]) question whether non-locality exists, despite years of confirmation of violations of Bell’s Inequality.

If - and it is a big IF - non-locality isn’t a thing, then quantum computing may be an illusion.

If quantum computing is illusory, then companies offering the “quantum-ready” are peddling FUD, snake-oil, no?

Thoughts?

[1] https://phys.org/news/2016-04-quantum-involves-nonlocality.html [2] https://www.imperial.ac.uk/media/imperial-college/research-centres-and-groups/controlled-quantum-dynamics/public/people/Matt_Pusey_MRes_new.pdf [3] http://backreaction.blogspot.com/2021/12/does-superdeterminism-save-quantum.html (recently discussed on HN, [5]) [4] https://www.researchgate.net/publication/325922318_The_notion_of_locality_in_relational_quantum_mechanics [5] https://news.ycombinator.com/item?id=29610441#29618846

PaulHoule2• 5 years ago

Quantum nonlocality is real.

The more books you read about Bell's Theorem the more confused you will get so unless you are doing experiments in that field you shouldn't read books about it... there's nothing to see there, move on.

The basis for nonlocality is that there is no wavefunction for "an electron" but there is a wavefunction for all the electrons. You can't tell the difference between electron A and electron B so you can change one for another and the wavefunction is the same except that the sign of the wavefunction is flipped because electrons obey Fermi-Dirac statistics.

If you swap Photon A and Photon B on the other hand the wavefunction is exactly the same because photons obey Bose-Einstein statistics.

That's all there is to quantum entanglement, and the two greatest miracles that result from it are.

(1) Two fermions cannot occupy the same quantum state, which makes matter stable. This is why atoms are stable and why you can sit in a chair. In classical mechanics solid materials are impossible!

(2) Bosons want to dogpile in the same state if they have the opportunity, which is the principle of operation of a laser.

Every time you use solid matter or a laser you are using quantum entanglement and that is every bit as profound as any other implication of the phenomenon.

PeterWhittaker2• 5 years ago

Have you read Rovelli’s work? As I understand it, Relatonal QM essentially says that there is no “FTL”’communication, because any effect of entanglement involves all of the “participants” exchanging information, and until they have done so, using sublimal communications, the entanglement is not resolved.

I’m using quotes to denote that participants are just the things involved, not necessarily people/observers.

PaulHoule2• 5 years ago

There is no FTL communication in God's geometry. We just talk about such things because we use our own geometry which isn't the real geometry of nature.

quocanh• 5 years ago

Wow. I actually just saw [a video from Sabine Hossenfelder](https://www.youtube.com/watch?v=ytyjgIyegDI) about exactly this. Long story short, we don't know if quantum nonlocality is real.

Bell's Theoreom doesn't prove nonlocality. It proves that locality is impossible with statistical independence, that is, the measurement itself affects the quantum system. We can preserve locality if we also accept superdeterminism, which Sabine succinctly puts as, "what the quantum particle does depends on what measurement will take place." We can accept nonlocality and statistical independence or locality and dependence. The former is taken for granted by Bell and many (most?) physicists today but only because the latter "feels" more spooky to a quantum physicist.

The video does the subject justice much better than I can, but the point is that it's not cut and dry!

mikewarot• 5 years ago

Nobody really knows the implications of a technology fully before it is deployed.

Thus every prediction about the effects of practical widespread quantum computing is a guess.

Look at the prediction thread here on HN from the eve of 2020, there are only 3 hints at the current public health crisis, and none of them were specific. I read them all a while ago... whew - https://news.ycombinator.com/item?id=21941278

Thus our ability here at HN to guess about the future is horrible.