It's a theoretical demand : $$ \begin{pmatrix} \nu_{e}\\ \nu_{\mu}\\ \nu_{\mu} \end{pmatrix} = \begin{pmatrix} a_{1,1} & a_{1,2} & a_{1,n} \\ a_{2,1} & a_{2,2} & a_{2,n} \\ a_{m,1} & a_{m,2} & a_{m,n} \end{pmatrix} $$
$ |\nu_{2}⟩|\nu_{3}⟩$
It's a theoretical demand : $$ \begin{pmatrix} \nu_{e}\\ \nu_{\mu}\\ \nu_{\mu} \end{pmatrix} = \begin{pmatrix} a_{1,1} & a_{1,2} & a_{1,n} \\ a_{2,1} & a_{2,2} & a_{2,n} \\ a_{m,1} & a_{m,2} & a_{m,n} \end{pmatrix} $$
$ |\nu_{2}⟩|\nu_{3}⟩$