Tag Info

For measuring 2 qubits, there are 4 possible outcomes, corresponding to projectors $$P_{00}=|00\rangle\langle 00|,\qquad P_{01}=|01\rangle\langle 01|,\qquad P_{10}=|10\rangle\langle 10|,\qquad P_{11}=|11\rangle\langle 11|.$$ So, if you have a state $|\psi\rangle$, you get the outcome $x$ with probability $p_x=\langle\psi|P_x|\psi\rangle$. This immediately ...
My understanding of the OP's question is that there is some restriction imposed that a gates can only act on Adjacent Qubits. While this isn't necessary, we can still work with this restriction using SWAP gates to make non-adjacent qubit adjacent. If the Control qubits are $i$ and $j$; and target qubit is $k$. Such that $i+1<j$ and $j+1<k$. Then we can ...