High-temperature Gibbs states are unentangled and efficiently preparable

by KolenCh • 2 years ago

80 33 2 years ago

empath75• 2 years ago

I'm very much approaching this from a level of "I know what some of those words mean", but is this result surprising that quantum systems lose entanglement at high temperatures? Isn't that the whole point of running quantum computers at very low temperatures?

tux3• 2 years ago

Registering my uneducated guess: Is this implying there was previously hope you could trap a hot system in a Gibbs state and demonstrate nice stable quantum supremacy with those, but they found hot Gibbs states are necessarily all boring and decohered after all?

hughesjj• 2 years ago

I believe so, from abstract

A priori the task of preparing a Gibbs state is a natural candidate for achieving super-polynomial quantum speedups, but our results rule out this possibility above a fixed constant temperature.

beefman• 2 years ago

johntb86• 2 years ago

https://www.quantamagazine.org/computer-scientists-prove-tha... gives the more layman-friendly version.

0134340• 2 years ago

So is this another blow for the free will argument based on quantum entanglement that some posited was happening in the brain? It seems this is another nail in the coffin leaving very few arguments other than mostly solipsistic ones.

Vecr5• 2 years ago

That was always the case, to argue otherwise required new physics. I.e. hypothetical physics that probably didn't exist.

blurbleblurble2• 2 years ago

I don't know about the free will argument, but this research doesn't really have anything to do with, for example, the possibility of stable entanglement between Posner molecules.

Beyond that, applications of quantum information theory and other quantum tools now extend beyond physics: there's no requirement that something be based on a physically quantum system for it to be useful modeled by quantum tools.

All in all, there are lot of ways to use quantum/quantum-like/post-quantum models now, both within physics and outside of it. Quantum stuff just isn't as monolithic as many orthodox physicists would suggest.

Vecr5• 2 years ago

You can't use it outside of physics, because the combination of digital computers and human brains this hypothetical stuff runs on is in physics. GR (general relativity) + objective collapse (re. quantum physics) does not give you enough for the high-temperature speedups you want.

throwaway81523• 2 years ago

Wonder if it says anything against the idea that the whole universe has to be considered as a gigantic entangled quantum state, and that even gravity might arise from that entanglement?

niemandhier• 2 years ago

If it is not physics, shouldn’t we give it a different name that liberates it from all the physical imagery?

Something like “c* algebra based models”. “Quantum” carries to much baggage by now, things like “quantum healing” are just scams.

XorNot• 2 years ago

The free will argument has always been junk though because it's based on a bait-and-switch: "quantum mechanics is random, and therefore the future is not predictable with certainty" gets turned around into "so I have free independent will".

You should be able to see the problem: random events are not free will, they're random. The only thing it concludes is that some part of your perceived decision making is no longer predictable - it doesn't mean "you" are in charge of it somehow.

davidmurdoch2• 2 years ago

My credentials are: I really like reading and watching scientific fiction.

I think the idea of free will and quantum randomness is that the randomness can be influenced by :magic: something else :magic:, e.g., a soul/spirit/diety.

Combining any of wave theory, quantum entanglement, quantum randomness, and string theory and you've got all sorts of fun ways to attempt to justify the idea of free will.

(not taking sides on free will here, I'm just stating there are nearly infinite reasons for it's existence that will be made)

jusssi2• 2 years ago

Not arguing against the philosophy here, but wouldn't sufficiently unpredictable make it indistinguishable from free will, for practical purposes?

kaon_• 2 years ago

I would say when it comes to free will you have no choice but to believe in it.

anthk4• 2 years ago

It doesn't matter how does it work inside. There's no free will, you are bound to the action of the physics from the Universe. Period.

XMPPwocky• 2 years ago

What makes you say that? Have you read serious arguments against this view (ideally from academic philosophers, not somebody like me on HN!)?

gitaarik2• 2 years ago

What if free will is part of the formula in the the laws of the universe?

layer8• 2 years ago

Free will doesn’t make sense in any case. Either your will is causally determined, or there is a truly random component, which however doesn’t bring you any closer to influencing your own will.

High-temperature Gibbs states are unentangled and efficiently preparable

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