We establish that a perfect-transmission scattering problem can be described
by a class of parity and time reversal symmetric operators and hereby we
provide a scenario for understanding and implementing the corresponding
quasi-Hermitian quantum mechanical framework from the physical viewpoint. One
of the most interesting features of the analysis is that the complex
eigenvalues of the underlying non-Hermitian problem, associated with a
reflectionless scattering system, lead to the loss of perfect-transmission
energies as the parameters characterizing the scattering potential are varied.
On the other hand, the scattering data can serve to describe the spectrum of a
large class of Schroedinger operators with complex Robin boundary conditions.Comment: 7 pages, 5 figure