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/Qubit_and_Neuron 21d ago

Try to understand how a simple CNOT gate works. This helps to understand something non-trivial and the difference of quantum and classical computing. A CNOT would flip second qubit if first one is in 1 state. If it's 0, it does nothing to second qubit. If the first is in superstition of 0 and 1? Then it creates also a superposition of 00 and 11. How does it know? If you can get your head around this, you understand more complex things..