- #1
jdstokes
- 523
- 1
Homework Statement
Using the orthonormality of [itex]|+\rangle[/itex] and [itex]|-\rangle[/itex], prove
[itex][S_i,S_j]= i \varepsilon_{ijk}S_k[/itex]
where
[itex]S_x = \frac{\hbar}{2}|+\rangle \langle - | + | - \rangle \langle + |[/itex]
[itex]S_y = -\frac{i\hbar}{2}|+\rangle \langle - | + | - \rangle \langle + |[/itex]
[itex]S_z = \frac{\hbar}{2}|+\rangle \langle + | - | - \rangle \langle - |[/itex]
The Attempt at a Solution
Since S_x and S_y commute, their commutator should be zero which contradicts [itex][S_x,S_y]= i S_z[/itex]. What am I missing here?