GHZ experiments
GHZ experiments provide evidence against local hidden-variable theories. They confirm the apparent nonlocal effects of QM. In this article, I'll explain a GHZ thought experiment using qubits. I aim to be as simple and concise as possible. Notation We'll work in the qubit basis \(\{\textbf{0},\textbf{1}\}\) and use the following other states in this article. \(\textbf{+}=\textbf{0}+\textbf{1}\) \(\textbf{-}=\textbf{0}-\textbf{1}\) \(\textbf{R}=\textbf{0}+i\textbf{1}\) \(\textbf{L}=\textbf{0}-i\textbf{1}\) \(\textbf{GHZ}=\textbf{000}+\textbf{111}\) We won't worry about normalizing states and we simply bold symbols of quantum states (rather than using ket notation or other). We will measure individual qubits either on \(\{\textbf{+},\textbf{-}\}\) or \(\{\textbf{R},\textbf{L}\}\). We refer to the first measurement as \(M^+_-\) and the latter as \(M^R_L\). GHZ State Notice the last state \(\textbf{GHZ}\) defined in the prior section. ...
