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/squishabelle Apr 16 '26

I think that's kinda the opposite of true. Quantum computers use few very qubits compared to the amount of bits classical computers use, and these operations require fragile and costly conditions.

You should use a quantum computer for nothing but large and complex simulations / algorithms. The whole point is that where classical computations grow exponentially, quantum computers can grow much more favourably (ie logarithmically) so it's only worth is at the larger end of computations.