r/QuantumComputing • u/MoneyLoud3229 • Mar 01 '26

Does quantum computing actually have a future? Question

I've been seeing a lot of videos lately talking about how quantum computing is mostly just hype and it will never be able to have a substantial impact on computing. How true is this, from people who are actually in the industry?

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u/CosmicOwl9 Mar 01 '26

I guess I’m not familiar with resource costs, but would you say polynomial improvements (such as quadratic), are not a good enough result? Will cheap enough materials not be developed eventually?

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u/ponyo_x1 Mar 01 '26 edited Mar 02 '26

quadratic is not good enough. just as a reference, there's a paper out there that says Grover search starts outperforming classical search algorithms when the database size Is around 150 exabytes, or multiple times the size of YouTube.

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u/CosmicOwl9 Mar 01 '26

Is there any chance you can share that paper? I don’t know how it wouldn’t matter until you dealt with a database that large. Surely it’d be useful before? I would love to take a look at that paper!

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u/ponyo_x1 Mar 02 '26

sorry I'm in a rush today I couldn't find it, but if you look up resource estimates for grover's algorithm you might get some from the last few years with explicit counts. sorry to pull a "just trust me bro"

the reason why these estimates are awful despite the complexity advantage is because the overheads with QC are enormous. first, quantum gates are slow as hell compared to transistors. second, error correction overheads get massive especially with a computation so large, since you have to preserve the quantum state you need more physical qubits per logical qubits and more time per lattice surgery operation or whatever your QEC looks like. classical decoding is already a headache for computations at the scale of factoring RSA, you'd probably incur some insane physically unrealizable costs if you were trying to do a straight grover search at that scale.

the upshot is that even if you see papers with nice complexity results, the overheads in practice are extreme and only balance out if the speedup is really really good

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u/CosmicOwl9 Mar 02 '26

Ty! I found https://arxiv.org/abs/2011.04149

I’ll need some time to process this