Quantum logic gate

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= Quantum gate
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At <quantum computing is just matrix multiplication>{full} we saw that making a quantum circuit actually comes down to designing one big <unitary matrix>.

We have to say though that that was a bit of a lie.

Quantum programmers normally don't just produce those big matrices manually from scratch.

Instead, they use </quantum logic gates>.

The following are the main reasons for that:
* <quantum logic gates are needed because you can't compute the matrix explicitly as it grows exponentially>{full}
* <quantum logic gates are needed for physical implementation>{full}


 Quantum logic gate