@RKuboAF; @AndersonAF], $ {\cal{H}} =  \sum_{\mathbf{k}}  \hbar \omega _{\mathbf{k}} ({\cal{A}}_{\mathbf{k}}^{\dagger } {\cal{A}}_{\mathbf{k}} + {\cal{B}}_{\mathbf{k}}^{\dagger } {\cal{B}}_{\mathbf{k}})$, in terms of Bogoliubov quasiparticle operators, ${\cal{A}}_{\mathbf{k}}$ and ${\cal{B}}_{\mathbf{k}}$, satisfying 