Coupled-channel version of PT-symmetric square well
  Coupled pair of PT-symmetric square wells is studied as a prototype of a quantum system characterized by two manifestly non-Hermitian commuting observables. We demonstrate that there exists a domain of couplings where both the respective sets of eigenvalues (viz., energies and spin projections) remain real and where the model acquires a consistent probabilistic interpretation mediated by an `ad hoc' scalar product. 
Miloslav Znojil