Hi I am studying Quantum computing and basically have no understanding of quantum gates and my lecturer is not very helpful.(adsbygoogle = window.adsbygoogle || []).push({});

I don't understand why a 4x4 quantum gate would ever effect a two qubit system because surely that is at best only a 2x2 matrix, assuming they effect each other through multipication.

How can there be a gate which flips the first qubit and leave the second one unchanged, surely they would both be affected?

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# Can anyone explain quantum gates

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