Ask here about the “Measurements” Codebook topic from the “Single-Qubit Gates” module.
Hey, I’m having trouble understanding why when we want to measure in the Y basis we have to take the adjoint of the operation that takes 0 yo y_+ and 1 to y_- and not the direct operation? Why is this?
Hi @yaelbaca2001 ,
Welcome to the Forum!
From the last two paragraphs in the theory section of the “Measurements” Codebook topic you can see that we need to use an operation that maps the new basis (e.g. the Hadamard basis) back to the computational basis. If you want to measure in the Y basis this would mean an operation that maps \vert y+ \rangle to \vert 0 \rangle and \vert y- \rangle to \vert 1 \rangle.
So if you already have an operation that takes you from the computational basis to the Y basis, the operation that takes you from the Y basis back to the computational basis is its adjoint 
.
Let me know if this makes things more clear!
yes!, I can see it now, thanks!
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