The particular form of the 2×2 matrices corresponding to the operators ˆσ and ˆI in Eq. (98a) depends on the basis selected for the spin state representa...The particular form of the 2×2 matrices corresponding to the operators ˆσ and ˆI in Eq. (98a) depends on the basis selected for the spin state representation; for example, in the standard z-basis, in which the Cartesian components of ˆσ are represented by the Pauli matrices (4.105), the 4×4 matrix form of Eq. (98a) is \[\alpha_{x}=\left(\begin{array}{cccc} 0 & 0 & 0 & 1 \\ 0 & 0 & 1 & 0 \\ 0 & 1 & 0 & 0 \\ …
