Applying these ladder operators to the eigenstates | ℓ mn 〉 of the total angular momentum, azimuthal angular momentum and energy operators, the eigenvalues of the first Casimir operator, C 1, are seen to be quantized, n − 1. Importantly, by dint of the vanishing of C 2, they are independent of the ℓ and m quantum numbers, making the energy levels degenerate.