GHZ preparation with Hadamard and controlled-Z gates
= GHZ preparation with Hadamard and controlled-Z gates
{c}
{title2=$(|0\rangle^{\otimes n}+|1\rangle^{\otimes n})/\sqrt2$}
For $n\geq2$, apply a <Hadamard gate> to one <qubit>, then controlled-NOTs from it to all others. Replacing each <controlled-NOT gate> by a target Hadamard, a <Controlled-Z gate>, and another target Hadamard uses $1+3(n-1)$ allowed gates. Each one-qubit reduced state is $I/2$, proving entanglement across each qubit-versus-rest bipartition.