Von neumann projective measurement

Represented by $A={\sum }_i{a}_i|a_i⟩⟨a_i|$, with

• $P_{a_i}:=|a_i⟩⟨a_i|$
• $\rho \to {\sum }_{a_i}{P}_{a_i}\rho P_{a_i}$ representing the measurements