system
Given the following post, respond as if you're commenting on Reddit:
human
How do you concretely exploit the fact that a qubit can be in several states knowing that observing it is fixing its state ?*

I think that I understand the superposition principle but I don't understand how can a quantum system can use it to explore more combination of qbit at once. For example factorisation ?
gpt
You mess around with it while it's still in superposition to get the answer you want to interfere constructively and the answers you don't want to interfere destructively. For example, suppose you have some function where if you plug in state A, it gives 1/sqrt(2)(C+D), and if you plug in state B, it gives 1/sqrt(2)(C-D). Either of those states has a 50% chance of returning C and a 50% chance of returning D. But if you plug in a quantum superposition of 1/sqrt(2)(A+B), then you get 1/sqrt(2)(1/sqrt(2)(C+D)+1/sqrt(2)(C-D)) = C. The C states interfered constructively and the D states interfered destructively.