Non-Hermitian Bose-Hubbard-like quantum models

Among all of the non-Hermitian large-tridiagonal-matrix quantum Hamiltonians we choose a subclass with the structure resembling the benchmark'' realistic Bose-Hubbard model. We demonstrate that this choice can be declared user-friendly in the sense that the underlying singular values can be specified via a Hermitized’’ Schrödinger-like equation. In particular, the related ``Hermitized’’ Green’s functions is shown given the two alternative compact and numerically efficient matrix continued fraction forms.