What makes quantum computing so hard to explain?

Re:What makes quantum computing so hard to explain? by wolverine876 on Thursday June 10, 2021 @12:22AM (#27456622)

> But how can we know that there's no classical shortcut - a conventional algorithm that would have similar scaling behavior to the quantum algorithm's? Though typically ignored in popular accounts, this question is central to quantum algorithms research, where often the difficulty is not so much proving that a quantum computer can do something quickly, but convincingly arguing that a classical computer can't.

Why is this question so important? I can see how it's interesting, but if the quantum computer does the job faster than the known classical solution, why not use it? You wouldn't delay shipping your classical code until you could prove that nobody will ever find a better solution.

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Re:What makes quantum computing so hard to explain? by btilly on Thursday June 10, 2021 @12:36AM (#27456701)

Shipping your quantum algorithm requires access to a limited number of very expensive quantum computers that, for all intents and purposes, are not actually available.

A classical algorithm can be run immediately on commodity hardware tomorrow. And, most of the time, novel quantum algorithms actually can be matched or beaten classically.

Given that it makes sense to spend a small fraction of the cost of the needed quantum computer looking for the classical alternative. Preferably before you start investing in building the quantum computer.

See https://www.scottaaronson.com/blog/?p=3192 for an example of this back and forth.

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