Pauli Matrices

These are 3 matrixes used in Quantum Mechanics.

${\sigma }_1$

$$\left[\begin{array}{cc}0& 1\\ 1& 0\end{array}\right]$$

${\sigma }_2$

$$\left[\begin{array}{cc}0& -i\\ i& 0\end{array}\right]$$

${\sigma }_3$

$$\left[\begin{array}{cc}1& 0\\ 0& -1\end{array}\right]$$