  We introduce the isomorphism between the multi-state Hamiltonian and the
second-quantized many-electron Hamiltonian (with only 1-electron interactions).
This suggests that all methods developed for the former can be employed for the
latter, and vice versa. The resonant level (Landauer) model for nonequilibrium
quantum transport is used as a proof-of-concept example. Such as the classical
mapping models for the multi-state Hamiltonian proposed in our previous work
[J. Chem. Phys. (submitted)] lead to exact results for this model problem. We
further demonstrate how these methods can also be applied to the
second-quantized many-electron Hamiltonian even when 2-electron interactions
are included.
