It states that for a quantum state $|psirangle$, the probability of obtaining the eigenvalue of a measurable observable $A_i$ associated with the eigenvector $|a_irangle$ equals the scalar product $|langle a_i | psi rangle|^2$.


It states that for a quantum state $|psirangle$, the probability of obtaining the eigenvalue of a measurable observable $A_i$ associated with the eigenvector $|a_irangle$ equals the scalar product $|langle a_i | psi rangle|^2$.