Quantum Mechanics Demystified 2nd Edition David Mcmahon Page

[ \hatL_x = -i\hbar \left( y \frac\partial\partial z - z \frac\partial\partial y \right), \quad \hatL_y = -i\hbar \left( z \frac\partial\partial x - x \frac\partial\partial z \right), \quad \hatL_z = -i\hbar \left( x \frac\partial\partial y - y \frac\partial\partial x \right). ]

[ \sigma_x = \beginpmatrix 0 & 1 \ 1 & 0 \endpmatrix,\quad \sigma_y = \beginpmatrix 0 & -i \ i & 0 \endpmatrix,\quad \sigma_z = \beginpmatrix 1 & 0 \ 0 & -1 \endpmatrix. ] Quantum Mechanics Demystified 2nd Edition David McMahon

(Verify normalization: (\int |\psi|^2 d\Omega = 1) indeed for the given coefficient.) Spin is an intrinsic degree of freedom. The spin operators (\hatS_x, \hatS_y, \hatS_z) obey the same commutation relations as orbital angular momentum: [ \hatL_x = -i\hbar \left( y \frac\partial\partial z