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Incorrect stated effect of CNOT gate when viewed as a XOR gate in the docs #13348
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Thanks @tnemoz for starting this discussion. Do you mean the documentation here: https://docs.quantum.ibm.com/api/qiskit/qiskit.circuit.library.CXGate? Note that what it says is:
This is actually correct, because when we define the However, Qiskit's convention is important when describing the 4x4 unitary operator corresponding to the
which is different from a more standard big endian convention, which would give
I hope this clears possible confusion. |
I do!
I also agree with this. The Another way to see it is that when using Qiskit's convention, the observable representing the computational basis is represented as |
Hmm, I think I see your point of view, indeed the effect of a |
Environment
Not relevant.
What is happening?
The current documentation for the
$$|a,b\rangle\to|a,a\oplus b\rangle$$ $|0,1\rangle$ to $|1,1\rangle$ . Indeed, the actual effect of the
$$|a,b\rangle\to|a\oplus b,b\rangle$$ .
CXGate
states that its effect is:However, this is the effect using the textbook bit ordering. But for instance, the
CXGate
sendsCXGate
is:How can we reproduce the issue?
Not relevant.
What should happen?
The documentation should correct the effect from$|a,a\oplus b\rangle$ to $|a\oplus b,b\rangle$ .
Any suggestions?
No response
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