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The need for quantum computers remains small

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Re: The need for quantum computers remains small

#91

Post by throwawaymaths »

LeegleechN wrote: post #26

He's not wrong about the narrow algorithmic use cases (so far), but he's completely missing the utility for simulation of quantum phenomena (chemistry, microbiology, materials science). That use case alone completely justifies investing into them even if you don't care about advancing science.

For chemistry, you usually care about the quantum mechanics of an ensemble. Simulating a single molecule is less useful and chemistry is already a very good heuristic system for this. We would care about say: we have a 2-dimensional membrane with lipids and cholesterols, and, say, two proteins interacting in this membrane. Now, give me a molecule that either enhances or inhibits the interaction, and please constrain your search to molecules that can cross the blood brain barrier and which we can synthesize in under five "undergrad ochem" steps[0] using a set of feeder molecules with low supply chain risk (let's not depend on glutamate from China, e.g.)

I'm not sure this is something that QC can easily solve.

[0] undergrad ochem is actually a pretty good heuristic for which reactions one can perform at industrial scale, though high scale reactions might require catalysts you don't learn about in ochem

Re: The need for quantum computers remains small

#92

Post by morelisp »

derpherpsson wrote: post #77

If you are able of imagining the future, and capable of logical coherent thoughts, the statement "the need for quantum computers remains small" is just... damn narrow-minded and perhaps just plain stupid. If you can shave off a factor n in O(n^3) then O-B-V-I-O-U-S-L-Y it will change the world. If you don't see the obviousness in this, then why are you working with computers? Before you hate on me, did you even googl…

I've read the introduction (and, uh, a lot more). What specific algorithms do you have in mind where quantum supremacy seems a) likely (or even possible) and b) enough of an improvement to be world-changing?

Re: The need for quantum computers remains small

#93

Post by lukeplato »

xmcqdpt2 wrote: post #84
lukeplato wrote: post #79

Earlier quoted context omitted.

How do you possibly know the details of a future implementation?

Quantum chemistry isn't magic, it's been around since the sixties, we understand pretty well the resources required for calculations. I happen to have a PhD in it too. AFAIK on quantum computers there are only two algorithms that are currently considered near-term feasible for this problem (VQE, QPE) and they both require a number of qubits = 2 x number of orbitals N and a number of operations between N^2 and N^4. It…

Thank you for the response. i'll need to read more into VQE, QPE. Still, I'm hopeful that geometric/energy minimization methods like invariant point attention in alphafold and other geometric deep learning findings will translate into quantum chemistry someday

Re: The need for quantum computers remains small

#94

Post by mtlmtlmtlmtl »

bowsamic wrote: post #83
mtlmtlmtlmtl wrote: post #75

Earlier quoted context omitted.

Neat. I have no trouble believing Stephen Wolfram could be out of touch with the current state of QM given he's been busy with his physics project and what not. And he's a terrible speaker. That podcast was the longest in Mindscape history due to that. I think part of his view is also partially based on the Wolfram Project multiway causal graph framework and its implications on the measurement problem. It's an intere…

Yeah. Frankly I don't know much at all about Wolfram's work, other than that Mathematica is the best maths software in the world. As far as I have gathered, his work is so strange and different that it has very little contact with most physicists. I work in quantum measurement and non-linear quantum optics and no one discusses him, either on the experimental or theoretical side. He seems to be a smart maverick with a…

I wanted to add that indeed he does have a lot of money, and he has hired some very talented postdocs and PhDs with some of it. I have no doubt we'll see a lot of interesting new theory out of his group at least. And that's never a bad thing, even if the theory doesn't pan out.

Re: The need for quantum computers remains small

#97

Post by abeppu »

He sort of glosses by the need to upgrade from current cryptographic algorithms. But I wonder if in 20-30 years, we'll look back on the bad timing of having designed blockchains before post-quantum cryptography was on solid footing. Even if there are few problems where quantum computers have a clear advantage, it seems at least unfortunate that a lot of people spent a lot of time and resources building up "value" explicitly protected by those problems ... and decentralizing them in a way that makes upgrades challenging.

We like to imagine that quantum computers will be creating value for society by doing simulations about cutting-edge scientific problems. What if it just lets rich companies impersonate long-dead bitcoin whales?

Re: The need for quantum computers remains small

#99

Post by tromp »

abeppu wrote: post #97

He sort of glosses by the need to upgrade from current cryptographic algorithms. But I wonder if in 20-30 years, we'll look back on the bad timing of having designed blockchains before post-quantum cryptography was on solid footing. Even if there are few problems where quantum computers have a clear advantage, it seems at least unfortunate that a lot of people spent a lot of time and resources building up "value" exp…

I consider the odds of having quantum computers able to break discrete log within 3 decades to be rather minute. The challenges involved seem way larger than for something like making nuclear fusion commercially viable.

I also have a very hard time believing that

1) physical reality supports computing with a superposition of 2^{256} states each with an accurate amplitude of magnitude 2^{-128}, and

2) that we can engineer systems preserving such accuracies.

Re: The need for quantum computers remains small

#100

Post by rbanffy »

wintorez wrote: post #96

"I think there is a world market for maybe five computers." -- Thomas Watson, president of IBM, 1943

I came here to say precisely that. We don’t know yet what they could be useful for because we don’t have a single one that’s as capable as conventional computers were in 1943.
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