User:Pubbawup

$$\begin{bmatrix} 0 & {1 \over 2} & 0 & {1 \over 2} \\ {1 \over 2} & 0 & {1 \over 2} & 0 \\ 0 & {1 \over 2} & 0 & {1 \over 2} \\ {1 \over 2} & 0 & {1 \over 2} & 0\end{bmatrix}$$