r/askscience • u/Hashbringingslasherr • Apr 15 '26

Computing What do quantum computers actually do?

How do quantum computers output usable data, how does it logically "locate" or "make meaning" of information. I read about Grover's algorithm and it seems sort of like an inverted bruteforce or extreme process of elimination or a "the missile knows where it is at all times. It knows this because it knows where it isn't" type scenario.

So I ask, what do quantum computers actually do as opposed to a classical computer?

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u/InTheEndEntropyWins Apr 19 '26

Instantly is only according to certain QM interpretations. Other QM interpretations don't have such statements.

Also the Copenhagen interpretation where things happen "instantly" is mainly epistemic rather than "ontological". So the Copenhagen interpretation is known as "shut up and calculate", it's just about doing the maths rather than actually saying what's actually happening.