Update 5_operators_QM.md

src/5_operators_QM.md

@@ -302,6 +302,10 @@ and discuss the interpretation of these results.
 
 $$|a\rangle=\frac{1}{\sqrt 2} [|-\rangle]-i|+\rangle$$ and |b\rangle=\frac{1}{\sqrt 2} [|-\rangle]+i|+\rangle$$
 
+where $|\pm \rangle$ are the base vectors for a spin half system, and the operator $\hat{A}$ defined by
+
+$$\hat{A}|\pm\rangle=\pm \frac{1}{2} i \hbar$$
+